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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293501 (2023) https://doi.org/10.1117/12.3017203
This PDF file contains the front matter associated with SPIE Proceedings Volume 12935, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.
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Fourteenth International Conference on Information Optics and Photonics (CIOP 2023)
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293502 (2023) https://doi.org/10.1117/12.2691226
Compensation of phase errors has emerged as a paramount task in fringe projection profilometry. In this paper, an erosion-clustering connected domain segmentation algorithm is proposed to compensate for the phase errors of traditional temporal phase unwrapping (TPU). At the onset, two connected domain maps from the wrapped phase are generated with a threshold value of zero. Then the connected domain adhering parts due to noise and height abruptness are forcibly disconnected by an erosion algorithm. Finally, the separated valid points are clustered based on the minimum Eulerian distance method. The combination of several techniques enables the reconstruction of high-quality 3D geometry and endows our method with the flexibility to redress errors arising from the traditional TPU method. Experimental results demonstrate the effectiveness and versatility of the proposed method, building upon the existing TPU methods that obtain fringe orders.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293503 (2023) https://doi.org/10.1117/12.2691566
In order to discriminate the sense of velocity, this paper proposes a laser Doppler velocimetry system based on the phase shift method. First, the expression for the light intensity of the interference field is derived, and the relationship between the interference fringes in time is obtained. Then two signal reception channels are generated by means of optical methods with a phase difference of π/2 between them. Finally, the direction of velocity is identified according to the change in phase between the two signals caused by the change in the direction of movement of the object. The experimental results show that the direction of velocity can be effectively determined by using the phase discrimination method.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293504 (2023) https://doi.org/10.1117/12.2692164
There is a growing interest in the development of imaging flow cytometry techniques that can simultaneously capture dual-modality images of single cells on a single detector. In this study, we developed a label-free light-sheet dualmodality imaging flow cytometer that is capable of simultaneously capturing bright-field and two-dimensional (2D) light scattering images of individual particles on a single detector. The system uses the principle of hydrodynamic focusing to make the microspheres flow in a single file. The laser and metal halide lamp beams are combined as light sources, which are directed onto the microspheres, providing 2D light scattering patterns and bright-field images of single particles. The two optical channels to collect the scattering patterns and bright-field images are collected by a single CMOS detector. By employing this dual-modality imaging flow cytometry, we demonstrated the obtaining and analysis of the label-free bright-field and light-scattering images of individual micrometer-sized particles. The label-free light-sheet dual-modality imaging flow cytometry is promising for applications in single-cell clinical analysis.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293505 (2023) https://doi.org/10.1117/12.2692193
The aberration characteristics change with the relative position changes of zoom groups has been a key problem for continuous zoom lens design, especially those with large target surfaces. To diminish the aberration, in this study, we took a Positive-Negative-Positive-Positive (PNPP) Mechanical structure for optical compensation, and developed a continuous zoom MWIR lens system with 20x magnification. The system used a cooled detector with a large target surface of 1280×1024 pixel and a 12μm pixel size, which improved observing capability under a 66.5° field of view. We tested the transfer function of the system at Nyquist frequency, which is close to the diffraction limit in a 15~300mm zoom range and the full field of view. We further evaluated our system by ray tracing analysis, pressure angle analysis of the cam curve, and de-focusing amount analysis under a temperature range of -45℃ to +70℃. Results show that our system has a good suppression capability for cold reflection, high image quality under extreme thermal conditions, and a smooth zoom curve.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293506 (2023) https://doi.org/10.1117/12.2692340
As the electromagnetic environment becomes more and more complex and strong electromagnetic interference becomes normal, in order to improve the ability of ultra-wideband(UWB) communication under strong resistance and complex electromagnetic environment, the wideband communication anti-interference technology has been applied more and more widely in electronic information systems. Based on the advantages of microwave photonic technology such as ultra-wideband and anti-interference, this paper constructed an ultra-wideband adaptive anti-interference communication system by combining microwave photonic spectrum sensing and high-speed frequency hopping signal generation. In the ultra-wideband adaptive anti-jamming communication system, the spectrum sensing module carries out high-speed real-time sensing of electromagnetic environment, the intelligent processor decides the safe spectrum information according to the spectrum sensing information, and the frequency-hopping signal generation module generates high-speed frequency-hopping signals according to the decision information, which can realize the adaptive anti-jamming of ultra-wideband communication. In the simulation, the 2~18GHz frequency spectrum is perceived at a high speed by using a coherent optical comb, and a frequency hopping pattern is determined according to the perceived information. The frequency hopping signal generation module generates a frequency hopping signal of 20000 hops /s according to the frequency hopping pattern, which improves the adaptive recognition ability of the communication system in the UWB range.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293507 (2023) https://doi.org/10.1117/12.2692416
We investigate the photon statistics of two-mode photon-subtracted squeezed vacuum states (TMPSSV), which are important factors to affect the sensitivity and resolution of optical interferometers. The comparison between the photon statistics of TMPSSV and two-mode squeezed vacuum states (TMSV) shows that the non-Gaussian operation has the effect of narrowing the characteristic widths of photon number probability distributions. Different from the super-Poissonian statistical distribution of TMSV, when the initial squeezing parameter is lower, TMPSSV shows a sub-Poissonian statistical distribution which is desirable for enhancing the sensitivity and resolution of interferometers. Therefore, non-Gaussian entanglement based on TMPSSV provides a promising quantum resource for an ultra-sensitivity and super-resolution optical interferometer far beyond the standard quantum limit.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293508 (2023) https://doi.org/10.1117/12.2692944
Si3N4 microring (MR) stands out as a promising platform in the integrated photonics for optical filter, optical delay lines, generation of Kerr frequency comb and optical computing. In this work, we study the optical temporal differentiation in a designed Si3N4 MR array. In order to avoid the limitations of a single MR, which can not reproduce the third peak at the trailing edge when differentiation order is between 1 and 2, a MR array consisting of two add-drop MRs and one all-pass MR is designed. Simulation results show that by reusing the drop port of add-drop MRs, differential orders between 0 to 2 can be obtained from different output ports. Furthermore, we propose an optimization algorithm to select the parameters of MRs. As a result, the differentiation deviations for 4-ps input Gaussian pulse can be minimized when the interior-point method is employed. Calculation results show that the differentiation deviations for orders between 1 and 2 are reduced to around 10%, and for orders between 0 to 1 are reduced to within 33%.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293509 (2023) https://doi.org/10.1117/12.3000016
When observing astronomical targets from ground-based telescopes, sequential short-exposure astronomical image acquisition is usually performed, where the astronomical images exhibit constant distortion and quality changes, and atmospheric turbulence makes the captured astronomical images seriously affected by noise and severely reduces the resolution. In this paper, we use a deep neural network-based image distortion registration technique to eliminate atmospheric blurring by registering the sequential short-exposure astronomical images and superimposing the registered images to improve image quality. This paper introduces an attention technique based on the Cyclemorph network, which identifies three attention units on the feature extraction network and uses a self-gating soft attention technique to generate a trainable gating signal that allows the network to associate useful local information and then combines the feature vectors obtained from it to make the final prediction. Additionally, this soft attention method can help with accurate target localisation and boost the network's overall performance. To show how well the method works, it is applied to a collection of image datasets of really photographed astronomical targets as well as a set of image datasets of simulated astronomical targets built by a telescope atmospheric imaging model. The built networks go through independent training and testing. According to the experimental findings, the proposed method can successfully register consecutive astronomical photographs, neutralize the impact of atmospheric turbulence, and raise the resolution of astronomical images.
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Yuchen Li, Xuefu Shang, Yuanyuan Xu, Yan Geng, Furui Tang, Gubin Cai, Fan Yang, Yawei Wang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350A (2023) https://doi.org/10.1117/12.3000054
Tongue diagnosis is a way of aiding the diagnosis and identification of pathological conditions by observing tongue images in Chinese medicine diagnosis. The application of photo chromatography to diagnosis allows for the accurate and comprehensive extraction of tongue features. The main characteristic parameter of tongue diagnosis is color information, so this paper proposes a diagnostic method based on the proportion of the primary color of the tongue and the H-component to assist in the analysis. The method treats the tongue color and moss color as a whole, extracts the pixels and proportions of each tongue color and selects the primary color, uses a threshold method to distinguish between healthy and diseased tongue images based on the primary color proportion, and then uses a gray-scale histogram and H-component histogram to extract each feature parameter to achieve sub-classification of the diseased images. The experimental results show that the method is feasible, more stable and accurate than traditional methods, and can improve the diagnostic efficiency.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350B (2023) https://doi.org/10.1117/12.3000266
The selection of atmospheric sample profiles is one of the key factors affecting the accuracy of the fast simulation of satellite channels, but the mechanism of the influence has not been conclusively established. In this paper, the mechanism of atmospheric sample profile selection and its contribution in the forward modeling are discussed through the analysis of the role of transmittance predictors in RTTOV model. The CO2 absorption channel at 15 μm in the infrared band of FY-3C IRAS (InfraRed Atmospheric Sounder) is used as the study object, and the IRAS laminar channel transmittance factor is established based on the TIGR43 profile database. The comparison tests between the profile temperature anomaly and simulation accuracy in the cold and warm scenarios show that the root mean square error (RMSE) of the simulation for the IRAS temperature detection channel is 0.2 K when all the profiles are involved in the regression calculation, compared with the simulation results of LBL. Within the detection height range of the selected CO2 detection channels, there is a strong linear correlation between the profile temperature anomaly and the simulation accuracy in the warm scenario due to the higher order residual term in the Taylor expansion, and more significant accuracy improvement can be obtained if the profile with larger temperature anomaly is removed from the forward modeling.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350C (2023) https://doi.org/10.1117/12.3000492
Compared with traditional analog infrared focal plane detector, digital infrared focal plane detector has many technical advantages, which is one of the key directions of digital infrared focal plane detector technology. Firstly, this article introduces the development history of infrared focal plane array detectors, analyzes the differences between analog and digital infrared focal plane array detectors. After that, four different kinds of the current direction of infrared focal plane array technology are introduced. Then, this paper analyzes the structure and performance characteristics of related readout circuits, and summarizes the development and advanced research results of various companies in different array size and pixel pitch. Finally, the future development trend of digital readout circuit technology is stated.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350D (2023) https://doi.org/10.1117/12.3000590
High-speed (25 Gb/s) oxide-confined VCSELs operating at 850 nm have gained widespread use in data communications. However, ensuring their reliability remains a significant challenge. This study investigates the reliability and failure modes of 25 Gb/s 850 nm oxide-confined VCSELs through accelerated life testing and failure analysis. The high-stress life tests are conducted under various temperatures and bias currents. Aging data over a finite period are extrapolated using a power function to determine the life corresponding to the failure criterion. The median life is obtained by fitting a log-normal distribution function to the device life under different stress conditions. The precise junction temperature is determined using the spectral drift method, allowing for the extraction of key life parameters: activation energy (Ea) and current acceleration factor (n). The findings demonstrate a significant increase in the activation energy of InGaAs-based 25 Gb/s VCSELs compared to GaAs-based 10 Gb/s VCSELs. Additionally, high-resolution transmission electron microscopy (TEM) is employed to analyze failure samples subjected to three types of stress tests: high-temperature and high-humidity with bias aging, electrostatic discharge (ESD) damage, and high-temperature and high-current aging. Three main failure modes are identified and analyzed: dark line defects, electrostatic breakdown damage, and dark spot defects. These failure modes predominantly arise from the combined effects of the oxide layer's shrinkage stress and the InGaAs quantum well's compression stress within the device. This study provides detailed insights into the reliability and failure modes of 25 Gb/s 850 nm oxide-confined VCSELs, enhancing our understanding of degradation mechanisms in high-speed VCSELs featuring strained InGaAs quantum wells.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350E (2023) https://doi.org/10.1117/12.3000601
In order to avoid the complicated phase with height mapping relationship calibration and phase unwrapping process of traditional 3D surface measurement methods, a three-dimensional surface measurement method based on deep learning was proposed. By sampling the rotating fringe pattern, data samples of different directions of the object to be measured are obtained as the training set. After the model is trained well, the mapping relationship between the deformed fringe pattern and the height of the measured object can be directly obtained to realize the 3D surface shape measurement of the object to be measured. The computer simulation and experiment show that the method is effective.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350F (2023) https://doi.org/10.1117/12.3000602
Recently, free-space optical neural networks (ONNs) have gained extensive interest as emerging machine learning platforms for implementing artificial intelligence tasks, such as image classification. Despite various optical implementations of electronic neural networks (ENNs), the bulky volume of optical components remains challenging to deploy edge devices, such as Internet of Things peripherals, wearable devices, and camera. To address this problem, we propose a compact lensless optoelectronic convolutional neural network (LOE-CNN) architecture with a lensless optical analog processor utilizing a single optimized diffractive phase mask (DPM) to perform convolution operations without Fourier lens. Comparing the processor with a commercially available NVIDIA A100 Tensor Core GPU in terms of speed and power, indicates the optical computing platform enables to replace the electronic processor in latency reduction and energy savings. Furthermore, we compare the LOE-CNN with two all-electronic neural networks (i.e., fully connected neural network [FC-NN] and convolutional neural network [CNN]) over the Modified National Institute of Standards and Technology (MNIST) dataset and Fashion-MNIST dataset, respectively, and demonstrate that the LOE-CNN can be functionally comparable to existing electronic counterparts in classification performance. My study not only opens up new application prospects for free-space ONNs based on compact lensless single-chip convolution processor, but also facilitates the development of ONNs-based smart devices.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350G (2023) https://doi.org/10.1117/12.3000692
In this paper, a novel 1×2 MMI coupler is proposed in the 3 m thick-silicon platform, which is based on rib input/output waveguide and strip multimode core waveguide. The hybrid waveguide structure can achieve a low-loss optical transmission with 0.017 dB at 1550 nm which is a comparable performance of traditional strip MMI coupler. In addition, the proposed structure can directly join the power splitter with other optical element such as ultra-low-loss single-mode rib waveguide and high-speed electro-optical Mach-Zehnder interferometers, which is a strong candidate for the conventional waveguide transformer between strip coupler and rib modulator.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350H (2023) https://doi.org/10.1117/12.3000911
Existing particle size analysis methods are difficult to detect micron and submicron sized particles in transformer oil which generated during the early stages of transformer oil aging. As a supplement to the existing analysis methods, we introduce dynamic light scattering (DLS) to extended the lower limit of particle size detection to the nanoscale. In this work, we designed a novel multi-angle DLS system which utilizes optical fibers and microfluidic chips to achieve accurate measurement in high viscosity media. We use the self-developed system to analyze the particle size distribution in multiple aging transformer oil samples, the experimental results show that the relative errors of measurement for simulated aging samples are within 7%, and the measurement results for real aging samples are consistent with the microscopic observations.
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Gengze Wu, Jin Li, Jiaqi Zhao, Xin Zhang, Shiling Chen, Tao Pu, Jilin Zheng
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350I (2023) https://doi.org/10.1117/12.3003702
In this paper, the simple multi-band triangular frequency modulation (TFM) signals generation with multiplying bandwidth and center frequency using photon-photon resonance (PPR) effect in three-section monolithic integrated directly-modulated laser (TS_MIDML) has been experimentally demonstrated. The traditional optical-injection system replaced by the TS_MIDML, and the high-speed external modulator, polarization controller and filter are eliminated in this paper. A three-band TFM signals with carrier frequencies ranging from X-band to K-band are given as an example, and the time bandwidth product (TBWP) up to 20000. The numbers of bands and TBWP of generated signals could be easily adjusted by tuning the reference signal from arbitrary waveform generator (AWG). The results of auto-correlations of the generated waveforms are also given.
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Yishan Wang, Minnan Huang, Jiaming Fan, Xingchen Su, Chenglong Zhang, Lidong Lu
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350J (2023) https://doi.org/10.1117/12.3003923
Aiming at the sensitivity of Raman anti-Stokes scattered light to the temperature, a novel distributed optical fiber temperature measurement system based on automatic power correction algorithm is proposed and experimentally demonstrated. The power automatic correction algorithm is based on corresponding temperature data and power value of the scattering position for temperature calibration. And by the power and temperature conversion relationship of the Raman anti-Stokes scattering light, the measured Raman anti-Stokes optical time domain reflecting trace for temperature demodulation is corrected by the obtained power correction coefficient. Therefore, the influence of unfavorable factors in traditional single-channel and double-channel Raman optical fiber distributed temperature demodulation methods are eliminated, so that the stability and measurement accuracy of the temperature measurement system is improved. The experimental system is set up with multimode fiber (MMF) in a range of about 16.3km, and the experimental results achieved the spatial resolution of 2m and the temperature measurement accuracy of ±1.6℃, and the response time is less than 1.5s, which is of great significance to practical engineering application.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350K (2023) https://doi.org/10.1117/12.3003929
Holographic optical element (HOE) have been widely applied in many fields. However, the fixed focal length limits its application in dynamic optical systems. The existing methods have the problems of limited adjustment distance and difficulty in correcting the aberration during the adjustment. This paper proposes a method that can correct the aberration while adjusting the HOE focal length in a large range. This method modulates the illumination wave front by superposing the modulation phase factor to achieve the change of the reconstruction distance, that is, the change of the focal length of the HOE. To design modulation phase factors corresponding to different focal lengths, the relationship between the parameters of the modulation phase factor and the focal length of HOE was derived based on the Fresnel diffraction integral formula. To solve the problem of the aberration cannot be uniformly compensated at different focal length, aberrations of different types, sources, and reconstruction distances are compensated separately. The method proposed in this paper achieves a wide range of adjustment of HOE focal length and correction of aberration during the adjustment process. In the experiment, the focal length of HOE is adjusted to 30cm, 40cm, and 50cm, and the evaluation functions of aberrations have changed towards the direction of aberration reduction. This method can be used for the design and fabrication of adjustable HOE, which is expected to be used in holographic projection, structured light generation and many other fields.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350L (2023) https://doi.org/10.1117/12.3003964
The detection and imaging of the microvascular map play a vital role in providing valuable pathological evidence for a variety of physiological disorders. Optical coherence tomography angiography (OCTA) is a non-invasive technique that allows high-speed, high-resolution visualization of microvascular networks without the need for contrast agents and invasive manipulation. In this study, we developed a fiber-based polarization-sensitive optical coherence tomography (PS-OCT) system that utilizes a 200 kHz swept source at 1310 nm. To reduce phase artifacts and provide excellent motion contrast for vascular imaging, we have incorporated the complex correlated phase gradient variance (CCPGV) method. Additionally, to address the challenges posed by birefringence dispersion, we implemented a dual-state numerical dispersion compensation method. By imaging human skin, we have successfully demonstrated the effectiveness of our system in visualizing the vascular map while minimizing noise interference. The high-quality imaging and accurate visualization of vascular networks provided by our system hold significant potential in enhancing the understanding and assessment of various pathological conditions. This can benefit both researchers and clinicians in their biomedical investigations and patient care.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350M (2023) https://doi.org/10.1117/12.3004018
The Mueller matrix encompasses polarization information, correlated with microstructure and optical properties. However, coupling effects complicate the retrieval of anisotropy source values. To address this, we propose a novel approach of mapping the Mueller matrix onto the Poincaré sphere and introduce a set of Global-Polarization Stokes Ellipsoids (GPSE) parameters to potentially retrieve two primary anisotropic sources: cylinder scattering and birefringence. Using porcine skeletal muscle as the reference object, we establish a database of Mueller matrices and GPSE via Monte Carlo simulation and train regression models based on multi-layer perceptron (MLP). Experimental results demonstrate that GPSE achieves comparable or even better prediction performance for anisotropy numerical values compared to the Mueller matrix model, indicating that GPSE parameters effectively contain anisotropy information present in the Mueller matrix. With an intuitive expression form and sensitivity to anisotropy, GPSE holds great potential in retrieving the values of anisotropic sources in tissues.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350N (2023) https://doi.org/10.1117/12.3004025
The multiplexing of vortex beams carrying orthogonal orbital angular momentum (OAM) modes holds the potential to enhance the channel capacity (CC) of wireless optical communication systems. This paper proposes a method that utilizes optical phase conjugation (OPC) wavefront shaping by spatial light modulator (SLM), and regards the scattering medium diffuser (SMD) as an optical modulator to achieve the demultiplexing of multiplexed OAM beams through space channel. We also analyze the communication capability of the demultiplexing system in the atmospheric turbulence (AT) channel. In the proposed system, a simulation setup is employed where multiplexed OAM beams propagate through an AT channel simulated by a random phase screen. At the receiving end, the OPC method is used to obtain a phase mask that is loaded onto the SLM for wavefront shaping of the input multiplexed OAM light. The light field is then modulated through the SMD's multi-scattering effect, enabling the separation of multiplexed OAM beams to distinct detection positions for demultiplexing. This paper investigates the influence of the OAM mode and AT strength on the focusing of single-mode OAM beams. Additionally, it examines the impact of OAM multiplexing combinations, AT strength, and transmission distance on the detection probability, bit error rate (BER), and CC. The results demonstrate the effectiveness of the demultiplexing system in mitigating mode expansion caused by AT, offering valuable insights for the design of robust OAM multiplexing systems.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350O (2023) https://doi.org/10.1117/12.3004104
In order to satisfy the sensing requirement for low-concentration or even trace detection using Terahertz (THz) spectroscopy, a new metamaterial sensor (MS) based on a double-opening elliptical ring array is designed by electromagnetic simulations. After optimization of the MS structure, the proposed MS has a strong resonant peak absorption peak around 2.853 THz and is entitled with high-Q and high-sensitivity simultaneously. The Q-value of the designed MS can reach to 385.0 and the sensitivity can reach to 371.5 GHz/RIU for a dielectric analyte with a thickness of 30 μm and it still can remain 40.0 GHz/RIU for a very thin analyte with a thickness of 1 μm. These results indicate that the designed MS has good sensing performance and can potentially be applied to high-sensitive detection of low-concentration or even trace samples.
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Kequan Shi, Jun Wang, Hongna Zhu, Qi Li, Mingye Zhang, Hao Sui, Keyang Xia, Qian Ni, Ruixia Mao
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350P (2023) https://doi.org/10.1117/12.3004127
Underwater optical images are affected by light attenuation, scattering, noise, etc., resulting in low image quality. Therefore, it is extremely significant to improve image quality and optimize network detection performance for underwater target detection. In this work, a YOLOv8-based underwater target detection method via image enhancement is provided, making full utilization of its advantages in large-scale feature learning. To address the issue of insufficient detection accuracy of the YOLOv8 algorithm on the original optical underwater target dataset, we employ an image fusion-based image enhancement method to improve underwater optical image quality. Combining different weights and scales, this method fuses multiple enhanced images to eliminate scattering and color bias, which enhances target features significantly. The results illustrate that the designed YOLOv8-based algorithm via image enhancement improves the precision by 20.5% and exhibits better performance in small, multiple and overlapping targets scenarios, where this algorithm gives a promising way for underwater optics target detection.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350Q (2023) https://doi.org/10.1117/12.3004145
Infrared and visible image fusion technology aims to integrate the radiation information of infrared images and the details of visible images into one image, which is widely used in video surveillance, target tracking etc.. Thereinto, maritime surveillance often uses infrared and visible images to monitor ships. With the rapid development of deep learning technology, numerous image fusion algorithms have sprung up. However, maritime images can be affected by extreme illumination conditions during fused. Note that the quality of maritime images is extremely significant for identifying ship targets. Therefore, the quality of fused image is necessary for further investigation. Here, a progressive image fusion network with a lighting awareness module, named PIAFusion, is provided for maritime images fusion. Contributed by the light sensing subnetwork, PIAFusion can adaptively fuse the common information and complementary information of images. Evaluated with five operators in daytime and night cases, the results demonstrate that this method significantly improve the fused image quality, compared to common fusion methods (i.e., GTF and DenseFuse). In addition, this method preserves more details of the source image. The progressive fusion network illustrates better fusion performance for maritime images in different lighting cases.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350R (2023) https://doi.org/10.1117/12.3004152
The optical images quality in dark underwater background is usually degraded, influencing the results of accurate identification, terrain mapping and seabed exploration. Thus, the super-resolution methods for dark underwater optical images attract extensive research interest. In this work, the SwinIR model is provided for dark underwater optical images super-resolution. Here, the EUVP DARK dataset with dark underwater background is employed, which clusters 5500 paired images. The SwinIR networks has high speed of process with large-size image capability and plentiful image detail. Compared with the traditional SRGAN method, the super-resolution reconstruction speed increases about 18.3%, and the peak pignal-to-noise ratio (PSNR) and structural similarity (SSIM) of SwinIR test results on the EUVP DARK dataset increase by 14.4% and 15.8% respectively, the results illustrate that our method improving the accuracy and quality of reconstruction. In conclusion, the hierarchical structure of SwinIR and self-attention mechanism adaptive attention weights in generated to the image, enabling precise adjustment and control of detail and texture. This method provides an efficient approach to dark underwater image quality enhancement.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350S (2023) https://doi.org/10.1117/12.3004162
With the principle of electrically controlled birefringence (ECB), we propose a new method to spatially separate the azimuthally and radially polarized beams. The method is premised on a regularized arrangement of liquid-crystal (LC) induced by sparse polymer ribbons.The ECB effect was achieved by a hole-patterned LC device with an initial radial alignment, which is induced by polymer ribbons pre-fabricated on the substrate. The polymer ribbons were formed on the substrate via the ultraviolet (UV) mask exposure method, which has the advantages of low cost, simple fabrication process and can be used for mass production. When the voltage signals are applied to the fabricated LC device, a gradient refractive index distribution will form inside the device. Restricted by the inherent polarization-sensitive properties of the nematic phase, it corresponds to the extraordinary optical component, which is exactly the radially polarized beam. According to the above principle, the extraordinary and ordinary polarized components can be separated. Experiments demonstrated that the spatial separation was effectively achieved by the proposed LC device. The proposed method has provided an approach for the light field manipulation based on patterned liquid crystal alignment.
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Jing Bai, Yu Gao, Cheng-Xian Ge, Quan Yuan, Zhen-Sen Wu
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350T (2023) https://doi.org/10.1117/12.3004400
This paper investigates the scattering properties of a uniaxial anisotropic coated (UAC) sphere that is irradiated by two focused Gaussian beams with arbitrary directions using the generalized Lorenz-Mie theory (GLMT). We derive the dual Gaussian beam expression by utilizing the orthogonality of spherical vector wave functions (SVWFs). The SVWFs are employed to expand the electromagnetic fields within each region of the coated sphere, combined with the boundary conditions, and the scattering coefficients and the radar cross-section (RCS) for the scattering of UAC sphere irradiated by two Gaussian beams are obtained. We present numerical simulations of the angular distribution of the RCS. The effects of the waist width, the incident angle and the particle inner diameter on scattering intensity are analyzed. The findings demonstrate that when the particles are illuminated by two beams of light at varying incident angles, the E-plane RCS will attain its maximum value in the corresponding incident direction. Remarkably, when the two beams of light propagate in opposite directions, the angular distribution of RCS exhibits symmetrical shapes, and the H-plane RCS attain minimal value at ±90°. As the waist width increases, the RCS also increases, albeit with different increments at different angles. As the particle's inner radius expands, the RCS around 0° and 180° gradually increases, while exhibiting oscillations around ±90°. The theory and numerical analysis provide beneficial help for laser detection, scattering and optical manipulate of coating particles.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350U (2023) https://doi.org/10.1117/12.3004412
In order to reduce the active region temperature of single core semiconductor lasers and improve the reliability of packaging devices, based on the COS packaging form, this work conducted heat dissipation analysis on the established "sandwich" structure and composite stacked structure semiconductor laser models. The flip chip packaging structure was optimized, Graphene film was used to increase the transverse heat dissipation channel of semiconductor laser, and the longitudinal heat conduction was carried out in combination with the heat dissipation copper sheet. Finally, the structural model of Graphene composite heat sink was established using SolidWorks software. By using ANSYS finite element software for steady-state thermal analysis comparison, the goal of reducing the temperature and thermal stress in the active region of semiconductor lasers was achieved. The proposed composite heat sink model can provide a design idea and method for high reliability laser packaging structures.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350V (2023) https://doi.org/10.1117/12.3004603
Waveguide-coupled germanium-on-silicon photodetectors have garnered significant attention due to the sensitive infrared response of germanium and compatibility with CMOS technology, widely employed in high-density and large-scale integrated optoelectronic products. These inherent advantages have also led to the huge interest in germanium-on-silicon single photon diodes. In this paper, we present the design of a microring resonator enhanced germanium-on-silicon single photon avalanche diode. The microring resonator is designed to enhance the light absorption in germanium absorption region through resonant enhancement. Moreover, a three-terminals structure is implemented to mitigate the dark count rate. And by optimizing the doping concentration and width of the doping region, the electric field at the silicon-germanium interface is effectively suppressed, resulting in a significant reduction in dark current. We employ a 2D Monte Carlo simulator to obtain the photon detection efficiency. This microring resonator enhanced single photon avalanche diode demonstrates twice the photon detection efficiency compared to the same size straight waveguide detector. In conclusion, our designed detector exhibits higher detection efficiency and lower dark current compared to conventional devices. These results illustrate clear potential for integration with Si photonics for on-chip applications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350W (2023) https://doi.org/10.1117/12.3004923
Photonic random demodulator (RD) is a widely studied scheme to realize photonics-assisted compressive sensing (CS). Since CS via an RD requires a pseudo-random binary sequence (PRBS) bit rate that is at least twice the signal’s Nyquist rate, the generation of the ideal PRBS in practical systems requires a very large signal bandwidth and is difficult to achieve, leading to poor mixing results from the RD and limited performance of the photonics-assisted CS system. To solve this problem, in this work, we propose a method to compensate for the poor mixing results by using a complementary PRBS and a parallel optical path, thus achieving better CS results in the case of limited PRBS bandwidth. The feasibility of the proposed method is verified by simulation. When only a 4-Gbps PRBS with a bandwidth limited to 0 to 6 GHz is used and the signal to be sampled is a multi-tone signal lower than 1.6 GHz, it is difficult to reconstruct the multi-tone signal or the quality of the reconstructed signal is poor when the starting point is randomly selected for downsampling due to the non-ideal PRBS. When the complementary PRBS is also limited to 0 to 6 GHz, the quality of the reconstructed signal is also improved in most cases. The method proposed in this work provides a good solution for the realization of CS using photonics-assisted RD in real systems, which can reduce the influence of non-ideal PRBS on signal recovery without expanding the bandwidth of the used PRBS.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350X (2023) https://doi.org/10.1117/12.3004927
In recent years, due to harsh working environments, increased accuracy requirements, and limited fiber optic technology levels, the active all-fiber optical current transformer (FOCT) used in the power grid of China State Grid is equipped with optical power compensation modules and modulation voltage compensation modules. However, aging of the light source (10 years) and extremely low temperature (-40℃) can cause the compensation modules to fail, resulting in decreased measurement reliability and significant losses to the power grid system. In this paper, by simulating the working status of FOCT when the power source ages and the modulator function deteriorates, it is found that the second harmonic and phase modulation depth are parameters that can timely reflect the working status of the optical power compensation module and the modulation voltage compensation module. This provides reference for the monitoring of feedback FOCT and helps improve the stability of feedback FOCT.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350Y (2023) https://doi.org/10.1117/12.3004973
Optical frequency combs are increasingly being adopted in various measurement applications. However, the sensitivity of free-running optical frequency combs and the large size and complex connections required for locking equipment pose significant obstacles to their on-site application. To address these challenges, we present an integrated optical frequency comb repetition rate locking control system that greatly reduces the volume of the locking system.In this system, we firstly control the temperature of the resonator cavity to achieve a wide range of control over the effective length of the cavity. A temperature control box for the resonator cavity is designed, incorporating semiconductor cooling chips to regulate the temperature. Secondly, we employ piezoelectric ceramics to achieve small-scale stretching control of the resonator cavity length. These control methods work in synergy to achieve high-quality repetition rate locking. The use of a loop filter in the system establishes the dynamic performance of the repetition rate locking loop and effectively suppresses the high-frequency components of the phase discriminator output. Through testing of the research system, the temperature control system demonstrates a temperature control range of 20-40°C, with a temperature control accuracy of ±0.01°C. With the assistance of the temperature control system, the repetition rate locking system achieves a repetition rate locking duration of over 10 hours, with a fluctuation range of less than 5 mHz, an Allan deviation of 217 μHz@gate 1s, and a relative frequency stability of 3.89E-12.This system successfully achieves high-frequency stability and long-term locking of the optical frequency comb's repetition rate.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129350Z (2023) https://doi.org/10.1117/12.3005256
In this work, we propose and experimentally demonstrate an improved cylindrical liquid crystal (LC) lens that allows for lateral shifting of the optical axis by use of a simple electrode design. The proposed cylindrical LC lens has potential applications in various fields, such as light sheet imaging, beam shaping, 3D displays, and laser scanning. The lens is composed of two substrates with comb-type electrodes of equal width on their inner surfaces. The comb-type electrodes are arranged in parallel and aligned with each other. Each comb-type electrode is applied with two driving voltages, generating a parabolic and a linear voltage distribution respectively. The voltage difference (VD) between two electrodes contains a quadratic and a linear term, so the symmetrical axis of VD can be shifted by adjusting the four driving voltages. By controlling the VD across the aperture within the linear response region of the LC material, the parabolic VD generates a parabolic phase profile, and the optical axis shifts as the symmetrical axis of VD shifts. The driving method of four voltages to adjust the optical power and the position of the optical axis is described in detail. The combtype electrodes are developed using a standard photolithography process, and a cylindrical LC lens with an aperture width of 2 mm and LC layer of 50 μm is prepared. The results demonstrate that the optical axis can be shifted in the aperture with high precision while maintaining near-ideal phase profiles.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293510 (2023) https://doi.org/10.1117/12.3005258
To control the laser parameters and meet the requirements of precise physical experiments, it is necessary to accurately obtain the spectral width of the frequency-modulated (FM) light. The FM light has complex comb distribution that the morphological characteristics are different from the typical continuous spectrum. In this paper, we define the spectral width of the FM pulse according to the nature of the phase modulation and develop a correlation traversal algorithm based on spectral morphology matching. Then, we establish the relationship between the measured spectrum of the medium-precision spectrometer and the simulated spectrum and complete the spectral width calibration. The correlation of the measured spectrum and the simulated spectrum in 2.5 GHz frequency modulation, within the spectral width range of 0.05 nm ~ 0.30 nm is calculated. The correlation traversal algorithm can obtain a strongly correlated theoretical spectrum with an R-value greater than 0.9 for any measured spectrum. Through linear fitting of all data, we obtain the relationship curve between the -3dB spectral width measured by the medium-precision spectrometer and the calibrated spectral width. And the determination coefficient of the relationship curve is 0.9989. The results show that the spectral width calibration method has the advantages of strong correlation and high linearity. The spectral width calibration method completes the spectral width calibration of FM light for the first time, which lays a foundation for precise control of spectral parameters in inertial confinement fusion precision physics experiments.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293511 (2023) https://doi.org/10.1117/12.3005283
Neuromorphic computing system inspired by the human brain has the capability of breaking through the von Neumann bottleneck, which can improve the efficiency of data processing. To deploy efficient neuromorphic systems, the development of synaptic devices is imperative. However, achieving tunable synaptic behaviors in a single transistor remains challenging. In this work, a silicon nanowire-based photoelectronic synaptic transistor is developed to achieve tunable synaptic behaviors. Using the floating-body effect and a cylindrical surrounding double-gate (CSDG) structure, we simulated excitatory and inhibitory synaptic plasticity in a single device. Additionally, our device also simulated various synaptic characteristics by modulating the bias voltages and light pulses, such as excitatory and inhibitory postsynaptic current (PSC), short-term potentiation (STP), short-term depression (STD), long-term potentiation (LTP), and forgetting behavior. This study provides an effective strategy for developing tunable photoelectronic synapses. Furthermore, Si processing compatibility also makes the synaptic device a promising contender for the implementation of neuromorphic computing.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293512 (2023) https://doi.org/10.1117/12.3005437
The measurement of ultra-weak magnetic fields relies on the conversion of magnetic field information to atom spins using alkali metals. In this context, the detection of magnetic fields is accomplished through rotation angle measurement of linearly polarized light. This paper proposes a novel method to suppress mechanical errors between polarizers in the rotation angle measurement, taking advantage of the optical setup characteristics in atomic magnetometers. The method involves applying two separate frequency modulations to the pump beam and probe beam, effectively eliminating mechanical errors between the polarizers as a direct current component using a double-channel lock-in amplifier. Additionally, the double modulation method offers a solution to suppress shot noise caused by incident beam fluctuations or transverse spin relaxation, as well as mechanical errors among optical elements in the light path, enabling high-precision measurements.
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Teng Ma, Weishu Guo, Lumeng Liang, Jinning Hu, Ziyi Chen, Yucong Ji, Jian Lu, Haibo Zeng, Zhenhua Li, et al.
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293513 (2023) https://doi.org/10.1117/12.3005503
Full-color display has always been a research focus and technical difficulty in the field of display. One of the current research hotspots is the use of color conversion layer (CCL) technology to achieve full-color display. Ultraviolet or blue LEDs can be converted by CCL to achieve full-color pixel display. Compared with traditional technologies, this technology does not require steps such as mass transfer. This method greatly simplifies the processing of full-color display. In this paper, we propose a method to achieve two-color patterned display of perovskite thin films by laser direct writing technology. The laser acts on the perovskite quantum dot thin film covered by the polymer film to form pattern or array based on photo-quench. Then other color perovskite quantum dot solutions is spin-coated. At last, the upper quantum dot film is washed off with solvent. Due to the protective effect of the polymer film, the coexistence of two-color quantum dots is realized. This method not only broadens the application of quantum dots in display, but also provides a new idea for the subsequent laser direct writing technology to realize multi-color or even full-color display.
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Junwei Ju, Liwen Sheng, Zhiming Song, Lin Huang, Shan Qiao, Aiguo Zhang, Shuai Zhou, Yu Wei, Zhiming Liu, et al.
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293514 (2023) https://doi.org/10.1117/12.3005521
A no mode hopping and narrow linewidth external-cavity wavelength-swept laser (EC-WSL) based on a traditional Littman-Metcalf structure is proposed and experimentally demonstrated. The wavelength scanning output range of the proposed laser without mode hopping is from 1520.82 nm to 1579.95 nm (namely, 59.13 nm). The narrow spectral linewidth less than 100 kHz is simultaneously realized. Meanwhile, the output power of the presented laser exceeding 14.8 dBm over the entire wavelength scanning range is obtained. In view of the good tuning characteristics, we achieved now, the proposed EC-WSL may be used in practical engineering fields such as gas detection.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293515 (2023) https://doi.org/10.1117/12.3005741
In this work, an all-fiber high-power cascaded master-oscillator power amplifier (MOPA) system emitting frequency-stabilized single-frequency laser pulses at 1550 nm is presented. An external cavity laser diode with a narrow linewidth of 5 kHz is used as the seed source. Owing to the use of frequency locking components and a matched closed-loop system, the seed source has stable output frequency and power. The on-off extinction ratio of 80 dB is achieved by using digital and analog acousto-optic modulators in series. Then the seed laser is amplified by a three-stage cascaded all-fiber amplifier consisting of two pre-amplifiers and one main amplifier. The MOPA system delivers 200-ns laser pulses with a peak power of 800 W at a repetition rate of 10 kHz. The output laser has an operating linewidth close to the transform-limited. The polarization-extinction ratio is 20 dB, and the optical signal-to-noise ratio is higher than 45 dB. The monolithic all-fiber Erbium-Ytterbium co-doped pulsed fiber amplifier can be used as the high-energy radar transmitter of compact long-distance coherent Doppler lidar systems.
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Kuen Yao Lau, Sergei Firstov, Andrey Senatorov, Andrey Umnikov, Beibei Xu, Xiaofeng Liu, Jianrong Qiu
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293516 (2023) https://doi.org/10.1117/12.3005749
High-power lasers operating at the E- and S-bands that overlaps with the strong absorption band of water molecules have been exploited for applications such as medical diagnoses, laser therapy and lipolysis. This type of lasers can be realized with a MOPA (master oscillator power amplifier) configuration, consisting of a seed laser and a fiber amplifier, which allows one to achieve easily boosting the output power. However, the efficient fiber amplifiers operating in the E- and Sbands using most rare-earth-doped silica fibers is inaccessible. In contrary, the optical fibers doped with bismuth (Bi) capable of providing broadband amplification from 1100 to 1800 nm can be utilized to build a desired fiber amplifier. In this work, we demonstrated the output characteristics of developed amplifiers based on a Bi-doped 5GeO2 − 95SiO2 fiber (BGSF) drawn from a preform fabricated by the modified chemical vapour deposition (MCVD) technique. The corepumped fiber amplifiers are characterized by a small-signal gain of >20 dB at a wavelength of ~1440 to 1450 nm and the noise figure of ~4.5 to 6 dB. In addition, the fiber amplifier was employed to amplify a signal from a tunable continuous wave laser from 1390 to 1510 nm. This work presents the significance of Bi-doped fibers to build a fiber amplifier across E- and S-bands which could be attractive for medical diagnoses and laser therapy applications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293517 (2023) https://doi.org/10.1117/12.3005763
Fused silica is widely used in aerospace and precision integrated micro-optical sensors due to its high hardness, low coefficient of thermal expansion, high transmittance properties and high chemical stability in harsh environments. Due to the amorphous characteristics, fused silica wet etching is isotropic and cannot realize specific structural functional devices; dry etching process is complex, costly, and relatively low productivity. These characteristics make the processing of fused silica extremely difficult, with high cost and low yield. Femtosecond laser processing has been widely used in the processing of complex and fine three-dimensional structure of fused silica due to its wide adaptability of materials, high degree of processing fineness and non-mask processing technology, but the surface of the processed surface is relatively rough. Fine micro-optical devices can be realized by wet-assisted femtosecond laser processing. In this study, microstructural patterns were fabricated on fused silica using a tightly focused femtosecond laser by means of a self-developed ultrafast laser processing instrumentation. By controlling the laser processing parameters and the etching time of HF solution to realize the precise modulation of linewidth, period and height of the grating, one/two dimensional gratings, and the Fresnel zone plates with circular and elliptical focal points and the biomimetic compound eye microlens array were successfully fabricated. Finally, the performance of the fabricated optical components were characterized, which were comparable to theoretical simulation values. The results show that the total diffraction efficiency of the fused silica gratings fabricated using this method reaches 85.5%; the Fresnel zone plates and the bionic compound eye microlens array have good focusing effects. This study provides a reference method for the fine micromachining of hard materials such as fused silica, and provides a theoretical basis for its engineering application.
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Yimian Qin, Cunbao Ma, Lihao Huang, Yufeng Yuan, Minggong Sha, Xinli Ye, Kai Zheng
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293518 (2023) https://doi.org/10.1117/12.3005775
To manipulate on-chip mid-IR signals, it is pivotal to construct a waveguide with subwavelength energy confinement. However, a deep subwavelength optical waveguide always suffers from high signal crosstalk, resulting in an inevitable coupling loss of multi-channel communication. To solve this problem, in this paper, a mid-IR hybrid waveguide which is composed of a graphene/hexagonal boron nitride (hBN) structure and a dielectric waveguide, is designed to realize a strongly enhanced light-matter interaction, accompanied by a low crosstalk transmission. The surface-phonon-plasmon-polariton mode generated by the graphene-hBN is coupled to a nanowire dielectric mode to form a hybrid guiding mode. Benefiting from this hybrid mode, the results show that it is possible to minimize the crosstalk of two parallel waveguides by reducing the width of the graphene-hexagonal hBN structure even if the waveguide separation length is at the nanoscale, thereby enabling low crosstalk optical transmission. Our designed approach opens the door for possible uses in nanophotonic devices such as amplitude equalizers, mode multiplexers, and wavelength-selective switches in optical communication systems.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293519 (2023) https://doi.org/10.1117/12.3005782
The composite materials are widely used in the aerospace field due to their satisfying properties. However, the structural damage always appears at the manufacturing stage, and various defects are also produced during the service process. Ultrasonic detection is the most popular approach for Non-Destructive Testing, but challenges still exist in composite materials for their large acoustic attenuation and mechanical physical anisotropy. Herein, as an alternative to the conventional electric transducers, we propose a new optical ultrasonic sensor for the defect detection of aircraft composite structures. The sensor utilizes a ceramic ferrule to construct a low-fitness in-line interferometer. Thermoplastic polyurethane elastomer rubber (TPU) is employed as the sensitive film and a single mode fiber grating is involved into the optical interferometer to improve its visibility. The sensor response and stability are characterized in experiments, and the artificial defects in a honeycomb-like plate are identified in time/frequency domains. Owing to the high elasticity and good durability of TPU, the proposed sensor possesses excellent performance of high sensitivity and reliability for detecting weak echoes in harsh conditions.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351A (2023) https://doi.org/10.1117/12.3005837
A polarization-insensitive four-channel wavelength-division multiplexing (WDM) (de)multiplexer based on Mach-Zehnder interferometers is proposed and demonstrated. Polarization insensitivity can be achieved by utilizing the square waveguides and bend directional couplers (bend DCs) based on silicon oxynitride (SiON) waveguides. The WDM (de)multiplexer has an 800GHz spacing for LAN-WDM application. Two stages of cascaded MZIs are utilized to achieve a four-channel spectral response. For the realized WDM (de)multiplexer with Gaussian-like passbands, the polarization-dependent losses (PDL) are less than 0.7dB for all 1-dB passbands. The insertion losses are <~ 3dB and the crosstalk is <~ -12dB for both TE and TM polarizations at channel central wavelengths.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351B (2023) https://doi.org/10.1117/12.3005850
Gallium-based liquid metals (LMs), including elemental gallium and associated alloy metals, are notable for their liquid state at room temperature. These LMs have gained attention due to their safety, non-toxicity, and exceptional physical and chemical properties. They exhibit optical resonance in the UV-VIS-IR spectral range, making them potential alternatives to expensive precious metals like gold and silver. However, the optical properties of gallium-based LMs have not been fully explored, especially their photoacoustic property. Photoacoustic detection is a label free method based on photoacoustic effect, detecting the optical absorption contrast of samples through photoacoustic waves. Photoacoustic detection has the advantages of non-contact, highs sensitivity, good contrast and etc. Using the photoacoustic detection method, we can avoid the influence of light scattering on the metal surface and thus obtain the optical absorption of gallium-based LMs directly. In this paper, we report a photoacoustic detection system based on intensity modulated high repetition supercontinuum laser to explore the light absorption properties of EGaIn LM.
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Zhen Wang, Hao Sun, Jiacheng Tang, Kun Yin, Cun-Zheng Ning
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351C (2023) https://doi.org/10.1117/12.3005937
Bilayer molybdenum ditelluride (MoTe2) exhibits promising research potential in silicon-based optoelectronics due to its near-infrared emission band. Although previous studies have shown that the direct and indirect bandgaps are closely located, the origin of the dominant exciton in photoluminescence (PL) emission and the energy difference between the direct and indirect bandgaps remain uncertain. To address these issues, we performed comprehensive micro-PL and absorption measurements on monolayer and bilayer samples, incorporating electrical control, across a wide temperature range of 4 to 300 K. These systematic measurements determined that the dominant PL emission in bilayer MoTe2 arises from an intralayer exciton with a direct bandgap and the energy difference between the direct and indirect bandgaps in the bubble-strained bilayer sample with a strain of approximately 1% was estimated to be around 10 meV in experiment, consistent with theoretical calculations in the literature.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351D (2023) https://doi.org/10.1117/12.3005955
3D convolution based stereo matching network has a wide range of research prospects at present, such as 3D measurement, unmanned driving, etc., but there is still room for improvement in accuracy. This paper proposes a threedimensional matching method based on deep learning: In the feature extraction part, a multi-layer learning parameter guiding feature fusion module is proposed, which can preserve the pixel gradient of the edge when sampling under single channel image guide. Then, the instance whitening noise of the output feature map is calculated, which effectively eliminates image pixel shift and feature similarity through the covariance threshold. In addition to using the traditional SmoothL1 loss function, the algorithm calculates the stereo focus loss by designing the confidence detection network to adjust the cost volume. The algorithm is tested on SceneFlow and Kitti series datasets. Using a multi-layer guiding module, instance bleaching loss, and stereo focus loss simultaneously compared to the original version, the error between test result and Ground Truth in the first frame (D1 Loss) of are reduced by 30.6%(Kitti2015), and the three-pixel error (3PE) is reduced by 6.3%(Kitti2012), which verifies the effectiveness of the algorithm.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351E (2023) https://doi.org/10.1117/12.3005956
Wavefront shaping technique has been applied to actively control the intensity profile of optical speckles, and a recent progress is to realize glare suppression with the low-transmittance eigenchannels of the transmission matrices (TMs). This makes it possible to custom-tailor the speckle fields. For the purpose of suppressing glare at will, research about the properties of low-transmittance eigenchannels in glare suppression is demanded. In this paper, we report the area expansion effect of glare suppression with low-transmittance eigenchannels. With numerical simulations, we found the actual darkened area was larger than the set target area due to the transverse correlation of the speckle field. Their difference is related to the measuring noise of the TM and gets smaller with the increase of the noise intensity. We believe our research could help to design structured speckle fields, and it will be of significant for advanced applications of optical speckles.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351F (2023) https://doi.org/10.1117/12.3005987
In this paper, an optical solar reflector (OSR) composed of an aluminum-doped zinc oxide (AZO) metasurface, a dielectric layer (SiO2), and a reflective layer (metal layer) was designed based on Kirchhoff’s law, which combined high solar spectral reflection with high thermal mid-infrared emission performance. The effects of structural unit length, period, thickness, and dielectric layer thickness of the AZO metasurface on the solar spectral reflection and thermal mid-infrared emission (absorption) performance of the OSR were calculated and analyzed by using the time-domain finite-difference method, and a structural model of localized surface plasmon polariton (LSPP) based on broadband infrared enhanced absorption was established. The results show that the metal reflective layer material is Ag, and the OSR achieves the best absorption performance structure when the structural unit length L of the AZO metasurface is 1.1 μm; thickness h1 is 0.04 μm; period d is 1.3 μm, and SiO2 medium thickness h2 is 1.4 μm. The designed OSR model has two absorption peaks reaching 99% in the range of 2.5–20 μm and absorption rates greater than 80% in the range of 5.0–8.3 μm and 10.2–15.9μm. The top square resonant unit makes the OSR independent of polarization and angle. The results provide a new idea to further improve the absorption rate of OSRs based on broadband absorption.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351G (2023) https://doi.org/10.1117/12.3005999
In the field of computer vision such as target detection and 3D positioning, point cloud registration has always been one of the key problems, which requires alignment two point clouds through rigid spatial transformation, accuracy, robustness, speed and other factors. Point cloud registration based on deep learning has received a lot of research in recent years. Compared with the conventional methods, They show a great advantage in their registration performance, To improve the performance of deep learning on point-cloud registration, This paper uses Kernel correlation to compute and store the neighborhood information of point clouds, While extracting local geometric features by convolutional neural network and Offset_Attention module aggregation, Then use Singular value decomposition SVD to predict the final rigid transformation matrix, and finally achieve high-quality registration. In this paper, by training our model on the ModelNet40 dataset, And the source and target point cloud are sampled independently, And also extract the non-axisymmetric targets for additional tests, Achievalized a more equitable registration network experiment, the Root-mean-square deviation (RMSE) is 12.58% higher than before, which verifies the effectiveness of our network.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351H (2023) https://doi.org/10.1117/12.3006025
In recent years, photoacoustic imaging has become a new non-destructive medical imaging technology. In this paper, a photoacoustic imaging technology for human bladder cancer was proposed, which combined transurethral endoscopic photoacoustic excitation in bladder cavity with a transrectal photoacoustic signal detection. By establishing a three-dimensional( 3D) optical model of bladder tissue, the distribution of light energy deposition in the bladder tissue was obtained through the 3D Monte Carlo method. The velocity potential was used to calculate the photoacoustic signal, and the scanning photoacoustic image of bladder tissue was reconstructed. The results showed that the proposed photoacoustic imaging technique with transurethral photoacoustic excitation in bladder cavity was expected to detect early bladder cancer nondestructively.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351I (2023) https://doi.org/10.1117/12.3006029
The mid-infrared (MIR) band encompasses crucial molecular fingerprint regions and atmospheric infrared windows, making it highly significant for various applications such as environmental monitoring, biosensing, and medical diagnostics. In this study, we present the fabrication of a MIR microlens array (MLA) using a combination of highspeed femtosecond laser scanning technology and thermal imprinting technology. The resulting microscale convex MLAs were densely packed, with over one million units on a 2cm×2cm chalcogenide glass (CHG) surface, offering adjustable sizes and non-spherical contour profiles. The CHG MLAs demonstrated exceptional imaging performance, achieving a high transmittance of 60-70% within the 2.5 ~ 15μm range. This technique boasts advantages such as low cost and high efficiency, presenting significant potential for widespread applications in the forefront of the mid-infrared field.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351J (2023) https://doi.org/10.1117/12.3006034
Accurate measurement of photosensitizer concentration in real-time in vivo bladder tissue was beneficial for improving the effectiveness of photodynamic therapy and achieving precise treatment of bladder tumor. In this paper, the potential ability of a transurethral photoacoustic imaging technique in visualizing and monitoring the photosensitizer concentration in the photodynamic therapy of bladder was evaluated. A bladder tissue optical model was established, and 3D Monte Carlo light transport method was coupled to calculate the photoacoustic signal. Photoacoustic signals in different photosensitizer concentrations were recorded. Results illustrated that a clear linearity between the photoacoustic signal intensity and photosensitizer concentration can be observed. It revealed that the proposed transurethral photoacoustic imaging technique has the potential to estimate in vivo photosensitizer concentrations and to guide laser-induced photodynamic therapy of bladder tumor.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351K (2023) https://doi.org/10.1117/12.3006037
In recent years, research interest has rapidly increased in the selective metallization of different substrate materials (flexible substrates and hard and brittle materials). Due to their unique optical and electrical properties, the fabrication of metal patterns on various substrate materials has a wide range of applications. These include micro-electro-mechanical systems, micro-heaters in micro-fluidic systems, electrodes for electronic devices and flexible wearable devices. However, the differences in the properties of the substrate materials themselves lead to poor adhesion of the metal micropatterns to their substrate materials, which is one of the main factors affecting the selective metallization of their surfaces. Therefore, a method for selective preparation of high-performance patterning is needed. Laser direct writing technology, as an emerging low-cost, high-efficiency and high-precision processing technology, can realize the preparation of fine metal selective patterning. This is significant for preparing optoelectronics and semiconductor micro/nanostructures and devices. This paper reviews the research progress related to the preparation of highperformance Cu metal micropatterning by laser direct writing, which mainly includes laser direct structuring, laserinduced selective activation, laser-induced selective reductive sintering of metal precursor nano-inks and laser-induced forward transfer. By reviewing the research of this group and the current related research results, the current research status of the preparation of selective metal patterning in different substrate materials is investigated and introduced from the fundamental mechanisms and process characteristics of the various methods. This paper can provide a reference for the research and application of high-performance Cu metal micropatterning prepared by laser direct writing. These high-performance metal micropatterns are useful for microcircuit defect repair, glass heating devices, and transparent atomization devices, which could be a potential option for various microsystems.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351L (2023) https://doi.org/10.1117/12.3006072
Laser active suppressing jamming is one of the most effective technologies to cope with electro-optical imaging system. In order to obtain the exact assessment of laser jamming effect, we must acquire the laser jamming effect image. We proposed two methods for simulation implementation of laser jamming effect image in this paper, which were respectively based on theoretical model and measured data. First of all, the implementation flows of two methods were introduced. Secondly, we successively finished the simulation of laser jamming effect image according to the two flows. By comparing with the measured image, the significant correlation can be obtained with the method based on measured data, regardless of whether the jamming laser energy was high or low. The significant correlation can be achieved with the method based on theoretical model when the jamming laser energy was low. The research results can provide the technical reference for carrying out laser jamming experiment.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351M (2023) https://doi.org/10.1117/12.3006093
An approach to generating pulse trains with user-defined pulse positions in a phase-modulated optical frequency-shifting loop (OFSL) is proposed and experimentally demonstrated. In this method, the OFSL operates in the integer Talbot state, i.e., the repetition frequency of the driving waveform is equal to the free spectral range (FSR) of the OFSL. The phase of the optical field in the OFSL is manipulated by using an electro-optic phase modulator (PM) in each round trip. Then, pulses will be generated in the positions that the additional phase introduced by the PM is equal to an integer multiple of 2π in each round trip. Hence, the positions of the generated pulses can be controlled by designing the driving waveform. In the experiment, we firstly demonstrate the ability of the proposed scheme to control the pulse positions by applying four types of signals, namely, a linearly chirped waveform, a dual-chirp waveform, a quadratically chirped waveform, and a sinusoidal frequency-modulated waveform, to the PM. In addition, the proposed scheme can also be used to generate pulse trains with coded pulse positions. To verify this ability, two groups of coding sequences, i.e., “0101101110” and “1010010001,” are used to encode the pulse positions in a round-trip time of the OFSL. The proposed scheme can generate pulse trains with user-defined pulse positions, which can be used as a pseudo-random sampling source in compressed sensing (CS) systems.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351N (2023) https://doi.org/10.1117/12.3006110
The ultrasonic detection technology of railway locomotive wheels is of great significance to the safety of train operation. However, the current detection technology relies on experts ' manual operation, which has the disadvantages of low accuracy and high cost. In this paper, a detection method based on improved Exceeding YOLO Series in 2021 (YOLOX) is proposed. Firstly, a series of processing such as cutting and rotating the ultrasonic B-scan image obtained by LU system is carried out to obtain the B-scan data set of wheel ultrasonic defects after data enhancement. Secondly, we add an adaptive spatial feature fusion block (ASFF) to the tail of the Neck module of the YOLOX detection algorithm, and further improve the multi-scale feature map. Finally, the original BCEWithLogitsLoss in the loss function is replaced by FocalLoss to improve the ability to distinguish defects from similar backgrounds. The test results show that the detection rate of each type of the improved YOLOX model is more than 90 %, the false negative rate and false positive rate are less than 10 %, and the detection speed is 17 ms. Compared with the original YOLOX network and other mainstream detection models, the improved YOLOX model has the best detection performance. This study provides a new idea for the automation of ultrasonic testing of train wheels.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351O (2023) https://doi.org/10.1117/12.3006148
An approach to generating local oscillation (LO) microwave signals with low close-to-carrier phase noise is proposed and experimentally demonstrated based on employing cascaded optoelectronic oscillators (OEOs). In this scheme, an actively mode-locked OEO (AML-OEO) is used as the master OEO to generate a microwave comb with low close-to-carrier phase noise. Then, the generated microwave comb is injected into the slave OEO with a well-designed loop delay to form an injection-locked OEO (IL-OEO). Owing to the different transmission frequency response curves between the two OEO loops, a single tooth is selected from the injected microwave comb and is regenerated in the slave OEO cavity, while the unselected teeth are effectively suppressed. Benefited from the injection locking effect, the low close-to-carrier phase noise characteristic of the microwave comb from the AML-OEO is transferred to the regenerated LO microwave signal from the slave OEO. In such a case, an LO microwave signal with low close-to-carrier phase noise is generated by the proposed cascaded OEOs. A proof-of-concept experiment is carried out to verify the feasibility of this scheme. In the experiment, an LO microwave signal at 10 GHz is generated, where the spurious suppression ratio and the close-to-carrier phase noise are measured to be 22 dB and -85 dBc/Hz@10 Hz, respectively. Compared to the LO microwave signal directly generated by the conventional OEO, the close-to-carrier phase noise is reduced by more than 30 dB.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351P (2023) https://doi.org/10.1117/12.3006306
Tunability of optical responses is crucial to the development of optical switch and optical code. The methods of light intensity modulation of changing external voltage, temperature, or hydrogen exposure of devices limit the flexible and realtime control of modulation. Herein, we propose a polarization-modulated nanosystem consisting of Au grating, TiN film, and SiO2 substate. The light reflection intensity is controlled by changing the polarization angles of the incident light. By adjusting the polarization state of incident light from transverse magnetic (TM) polarization state to transverse electric (TE) polarization state, the proposed nanosystem exhibits a plasmonic switch effect with reflection from 14.2% to 86.8%, and obtains a relative modulation depth is 511.3%. The reason of the light intensity modulation is the synergistic effect of the SPPs mode at the interfaces of Au/air and TiN/air excited by TM polarized light. The proposed nanosystem enriches the methods for light intensity modulation, and has potential applications in many fields including optical switch and optical code.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351Q (2023) https://doi.org/10.1117/12.3006334
Due to the wide application of welding in the modern industry, effective detection of weld surface defects is an important measure to ensure the quality of components, monitor the Service life of the structure, and ensure the safety of users. However, there are wrinkles and stains on the weld surface, which makes detection difficult. Based on the dynamic detection of pulsed eddy current thermography, a multi-feature fusion algorithm of infrared features and visible information is proposed in this paper. In dynamic detection, the relative position of cracks in the field of view is constantly changing, therefore, the thermal image sequences are spatially aligned to obtain the transient thermal response curve in static mode. Feature extraction and dimensionality reduction of thermal image sequences are carried out in time domain. The processed data is fused with the visible image features, and classified in pixel-level applying the pattern recognition network. The experimental results show that the proposed algorithm can effectively suppress the noise caused by weld texture and surface stains, and obtain more clear and accurate defect information. All 21 weld surface defects can be detected, and the detection ability is greatly improved.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351R (2023) https://doi.org/10.1117/12.3006803
Fringe projection profiling (FPP) is a technique to obtain the three-dimensional shape of an object by projecting periodic fringes onto its surface and analyzing the modulated fringes.The goal of this technique is to quickly and accurately obtain the three-dimensional shape of an object with as few fringe patterns as possible. This paper combines the fringe analysis steps of fringe projection profiling and deep learning, the proposed DARUNet network (Dense and Residual U-Net) introduces Dense Block and Residual Block on the basis of U-Net. Only three modulated fringe patterns with different frequencies need to be captured as the input of the DARUNet network, the network outputs the numerator and denominator of the wrapped phase corresponding to each frequency. After some post-processing, the three-dimensional shape of the object can be obtained. Deep learning relies on high-quality datasets, so this paper compares two methods for temporal phase unwrapping: Multi-frequency (hierarchical) and Multi-wavelength (heterodyne).The Multi-frequency method, which demonstrated superior performance, was chosen to create a high-precision 3D measurement dataset. Experiments show that the proposed network has higher precision in predicting the wrapped phase than U-Net and its series networks, and predicting the numerator and denominator of wrapped phase by fringes is also the optimal route for 3D reconstruction technology based on deep learning, this method achieves a high level of precision with a phase error of less than 0.1 radians and a depth error of less than 0.3 mm. Therefore, the method employed in this paper enables high-precision 3D measurements using only three frames of fringe patterns.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351S (2023) https://doi.org/10.1117/12.3006825
Three-Dimensional Displacement Sensing has a very important demand in research fields such as nanomanufacturing, lithography, and microscopic imaging. Optical displacement sensing has received considerable attention in recent years due to the advantages of non-contact and high-precision, etc. However, traditional methods that use optical phase or polarization singularities to obtain position information are affected by the intensity of light, making the detection difficult. Here, we propose a nanoparticle on waveguide film structure that utilizes the nanoparticle as a near-field probe to achieve three-dimensional displacement sensing. The scattering light of the nanoparticle excites the resonance modes of the waveguide structure and projects the generated signal to the far field. The far-field distribution has a strong angular correlation, and by detecting the relative strength of the corresponding angle in the far-field distribution, it is possible to achieve three-dimensional displacement sensing. We have theoretically verified this idea through the finite difference time domain (FDTD) method. The three-dimensional displacement sensor implemented by this structure may be applied in nanometrology, nanofabrication, and super-resolution microscopes.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351T (2023) https://doi.org/10.1117/12.3007228
Frequency conversion in homogeneous crystals suffers from a well-known trade-off: one can only achieve high frequency-conversion efficiency for a narrow acceptance bandwidth or vice versa. Nevertheless, adiabatic frequency conversion in non-homogeneous crystals may address the trade-off dilemma, allowing for both efficient and broad-bandwidth frequency conversion. A novel adiabatic nonlinear optical frequency conversion method based on the electro-optic effect is proposed, which can be applied in a plethora of bulky nonlinear crystals. In the method, the nonlinear crystal is placed in an electric field which modulates the refractive index in order to tune the phase mismatch. When the intensity of the electric field slowly and monotonously varies in space, the phase mismatch in the crystal varies accordingly, and in this way adiabatic frequency conversion can be attained. The validity and feasibility of this new approach is demonstrated by providing a theoretical framework and experimental evidence. In the experiment, the second harmonic generation of 532 nm is conducted in KD2PO4. Conversion efficiency approaching 47.2% is achieved, with a corresponding temperature acceptance bandwidth of 4.56°C, which is about 4.3 times the temperature without the external electric field. The approach based on electro-optic effect is promising to extend the range of applications of adiabatic frequency conversion and, consequently, to achieve efficient and robust frequency conversion. Moreover, when phase matching is disrupted by variations in system parameters, it is convenient to adjust the voltage to recover the phase-matched state, and which can further broaden the acceptance parameter bandwidth.
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Haojie Wang, Xikang Zhou, Xingfei Chen, Yiping Han
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351U (2023) https://doi.org/10.1117/12.3007272
Terahertz (THz) imaging technology has garnered considerable attention across a range of fields. However, its progress is constrained by the challenge of achieving high resolution. The terajet effect, utilizing dielectric structures, has emerged for super-resolution THz imaging. Nevertheless, the short terajets generated by the reported structures pose challenges for practical matching with the experimental setup. This study introduces a novel approach employing core-shell microspheres to generate long terajets with tunable characteristics. Numerical simulations reveal that precise tuning of core-shell properties leads to diverse terajets characteristics, encompassing variations in maximum intensity (53.6 V2/m2 to 261 V2/m2), focal length (0.05 λ to 3.8 λ), working distance (1.15 λ to 13.6 λ), and full width at half maximum (0.37 λ to 0.91 λ). These findings highlight the tunable potential of core-shell microspheres, holding promise for enhanced terahertz zoom imaging with improved resolution and adaptability.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351V (2023) https://doi.org/10.1117/12.3007280
High-power vertical cavity surface emitting lasers (VCSELs) are widely used in optical communication, optical storage, optical interconnection, sensing, and other fields. High-power VCSELs usually adopt a high-density array layout, and temperature is one of the key factors affecting their performance. In this work, the thermal characteristics of the VCSEL array with 1273 elements have been studied. A series of photoelectric characteristics such as the working voltage, output optical power, slope efficiency, electro-optical conversion efficiency, and spectrum of the device have been analyzed through a precision temperature control system. According to the relationship between the measured wavelength shift and the dissipated power, it is calculated that the thermal resistance value of the device increases from 1.319℃/W to 1.952℃/W, and the temperature rise of the active area is extracted. It can be seen that more temperature rises in the active region at higher ambient temperature for a given injection current, with a maximum value of 105.6℃. A thermo-electric coupling model was established to simulate the thermal distribution. The equivalent array method is employed to simplify the high-density array. The simulated results agree well with the measurement. As the ambient temperature rises, the thermal crosstalk phenomenon in the VCSEL array becomes more obvious. Heat diffusion becomes more difficult, resulting in more heat accumulation inside the device. The internal loss of the device is severe and the gain-cavity mode is seriously mismatched, so the photoelectric performance decays sharply. This research provides important guidance for the optimization and application of future devices.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351W (2023) https://doi.org/10.1117/12.3007337
Aiming to optimiziong axial chromatic aberration, this paper designed and compared three different dispersion lens configurations for spectral confocal displacement sensor. The designed three-piece dispersion lens exhibited a dispersion range of 6.706 mm, a linear fitting error of 50 nm, and a diffraction limit of 739 μm. The designed four-piece dispersion lens ultilized a dispersion range of 0.992 mm, a linear fitting error of 12 nm, and a diffraction limit of 30 μm. The designed five-piece dispersion lens yielded a dispersion range of 2.174 mm, a linear fitting error of 30 nm, and a diffraction limit of 69 μm. In summary, three-piece lens offered the largest detection range and a smaller linear fitting error. On the other hand, the four-piece lens exhibited the smallest dispersion range, while the fitting error and the diffraction limit were boasted the smallest to that of the three-piece lens. In terms of convenience of assembly and machining, the three-piece lens was superior, with identical glass types that facilitated easier processing and higher cost performance. However, for a balance between resolution and dispersion range, the five-piece dispersion lens should be the better choice.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351X (2023) https://doi.org/10.1117/12.3007340
With the rapid development of global communications and exponential growth of network traffic, the flexibility and dynamism of the modulation format and the transmission rate have become important characteristics of the development of the next generation of optical networks. The optical network must be capable of dynamically transferring signals of different modulation formats and data rates to satisfy the requirements of flexible and high-capacity optical network transmission. In this work, we propose a modulation format identification method based on the mean-shift cluster algorithm to implement the reception of different modulation format signals in high-speed optical communication adaptively. The proposed MFI is a spatial cluster method based on density distribution, which can automatically extract the cluster number and density information of samples by estimating the density distribution of samples in the space. In this paper, we construct a 10 GBaud coherent optical simulation system, transmitting QPSK, 8QAM, 16QAM, 32QAM, and 64QAM, to verify the feasibility of this method. The transmission fiber length of the simulation system is set to 80 km. In the case of considering the CD dispersion parameter to 16 ps/(nm·km) and the linewidth is 100 kHz, the simulation results show that the proposed MFI method can achieve 100% identification accuracy when the OSNR values are lower than the 7% FEC limit corresponding to the lowest required OSNR values for five commonly used modulation formats (MFs). Among them, when the OSNR values of 16QAM and 32QAM signals respectively are 17 dB and 21 dB, the identification rate reaches 100%, which can effectively complete the high-precision classification of different modulation formats.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351Y (2023) https://doi.org/10.1117/12.3007351
A parameter optimization method is proposed to enhance the performance of integral imaging (InI) and super multi-view (SMV) in light field three-dimensional (3D) display. The parameters of the light field display are categorized as system parameters and display parameters. By employing a multi-objective genetic algorithm, we optimize the system parameters to achieve the desired values for the display parameters. This approach takes into account the comprehensive impact of all display parameters on the imaging quality of light field 3D display. By setting different combinations of the weights in the genetic algorithm, the resolution, DOF and FOV is improved, respectively.
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Wenqiang Hou, Li Pei, Jingjing Zheng, Jianshuai Wang, Xiao Ye, Dingchen Wang, Lihong Wang, Fuhao Zhang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129351Z (2023) https://doi.org/10.1117/12.3007352
This paper presents a double-pass low-noise bismuth-doped fiber amplifier based on a Sagnac comb filter. The amplifier utilizes a Sagnac loop to filter out spontaneous emission light outside the signal wavelength, effectively decreasing the noise figure. Experimental results show that the amplifier achieves a minimum noise figure of only around 3.7 dB. Moreover, its gain bandwidth can cover a significant portion of the O-band. Under a forward pump power of 0.538 W, with an input signal power of -30 dBm, the amplifier can reach a gain of 29.6 dB, while the noise figure is only approximately 4 dB. Under backward pump, the gain difference for different input signal powers is larger compared to forward pump. We also studied the variation of gain with input signal power at a pump power of 0.5 W, using both forward and backward pump methods. The results indicate that the pump direction has a minor impact on the gain but significantly affects the noise figure, with the noise figure under forward pump being 1-2 dB lower than that under backward pump. Additionally, the amplifier exhibits a maximum saturation output power of approximately 9.5 dBm. In conclusion, this amplifier has great potential for application in WDM communication systems.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293520 (2023) https://doi.org/10.1117/12.3007376
Time-frequency synchronization is a basic element in some fields such as deep space exploration and satellite navigation. Its accuracy and precision are closely related to the measurement results of these systems. In high signal-to-noise ratio situation, the accuracy of time-frequency synchronization is affected by the Doppler frequency shift. In this study, we propose an interpolation model that can mitigate the impact of the Doppler frequency shift, which is constructed from the prior information of the system and related to phase difference of the pseudo-random code. A coherent heterodyne ranging system is built, which is phase-modulated by pseudo-random binary code. And interpolation model is experimentally verified. The experimental results show that the ranging deviation is not more than 0.55 mm for static target. For the moving target, the ranging deviation does not exceed 0.40 mm, and the deviation of the velocity measurement is within 0.45 mm/s.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293521 (2023) https://doi.org/10.1117/12.3007425
Phase sensitive optical time-domain reflectometry (Φ-OTDR) based on ultra-weak fiber Bragg grating (UWFBG) array measures the dynamic strain by extracting the phase of the reflective signals. However, the performance is challenged by the trade-off between spatial resolution and sensing distance. In this paper, we propose a wavelength division multiplexed (WDM) Φ-OTDR based on a cross-arranged dual-wavelength UWFBG array to overcome this limitation. By combining the vibration positioning results of two wavelengths, high resolution and long sensing distance can be achieved at the same time.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293522 (2023) https://doi.org/10.1117/12.3007439
Transport of intensity equation (TIE) provides a powerful QPI means due to its simplicity and high efficiency. However, it is limited in dynamic measurement because it requires at least two defocus intensity images acquisition. Therefore, a simple, accurate, full-field single-shot QPI method is proposed based on TIE and wavelength multiplexing scheme. By ultizing the different phase modulation capabilities of liquid crystal spatial light modulator (LC-SLM) for different wavelengths of light, multiple intensity images of different defocus distances can be produced by a Fresnel-lens-loaded LC-SLM. In this manner, those images can be acquired by a color camera with single exposure, enabling dynamic QPI application. computational imaging.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293523 (2023) https://doi.org/10.1117/12.3007528
Airborne Lidar Bathymetry measures ocean depth by transmitting 532nm wavelength lasers and recording the return energy and moment of the laser echo, and is an important means of acquiring the topography of coastal zones and shallow seas. Since underwater targets can also reflect the emitted laser, bathymetric lidar holds promise for underwater target detection. However, most of the existing echo simulation models for laser underwater transmission are for full field-of-view (FOV) and flat terrain, but there are few echo simulation models for hovering targets with sizes smaller than the FOV. Therefore, we combined the ray tracing and semi-analytical Montecarlo methods to simulate the laser echo energy of underwater targets. The model combined the speed advantage of the semi-analytical Montecarlo method with the ability to simulate echoes of underwater targets of arbitrary shapes. In order to simulate bathymetric lidar echoes under real operating conditions, the model also included simulations of the scanning mode and surface waves. The trend of the echo energy of an underwater target within the field of view with the deviation distance from the line-of-sight axis was investigated, and the results showed that even if the underwater target is deviated from the main axis, there is still an obvious target echo due to the scattering of the laser in the water, and the echo energy is weakened with the increase of the depth. The waves can make the ideal refraction direction change, which has a great impact on the quality of the scanned point cloud.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293524 (2023) https://doi.org/10.1117/12.3007547
In this study, we developed a twisted optical fiber surface plasma resonance (SPR) refractive index sensor using the helical structure of a dual side-hole fiber (DSHF) to measure refractive index sensitivity. The sensor structure consists of the helical DSHF integrated into a single-mode fiber (SMF) and a multimode fiber (MMF). Our experimental findings demonstrate that the twisted SPR refractive index sensor based on the helical DSHF exhibits excellent responsiveness within the refractive index range of 1.33 to 1.38, with a sensitivity of 1998.09 nm/RIU and a high linear correlation coefficient of 0.9571. This helical DSHF design offers numerous advantages, including high sensitivity, remarkable linearity, a wide measurement range, and ease of manufacturing.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293525 (2023) https://doi.org/10.1117/12.3007555
In this paper, based on the amplified spontaneous emission (ASE)-induced limited-band white noise modulation, a short-coherence laser source is developed for the wafer dynamic profilometry. All-fiber Mach-Zehnder optical path is constructed, obtaining the orthogonal-polarized light source with optical path matching for short-coherence dynamic interferometry. The 220-μm coherence length and 28 % side lobe suppression ratio (SLSR) of the modulated laser are realized in Fizeau interferometer. The dynamic profilometry of a 100-mm high-Al-doped glass wafer with 1.5-mm thickness is realized in the common-path interferometer, overcoming the interference fringe crosstalk induced by the front and rear transparent surfaces.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293526 (2023) https://doi.org/10.1117/12.3007564
Low coherent pulse bound states have drawn significant interests due to their distinctive structures and dynamic behaviors. Single- or dual-wavelength interference-induced noise-like soliton molecules (NLSMs) characterized by the crossing features of a broad autocorrelation pedestal of noise-like pulses (NLPs) and symmetrically distributed autocorrelation multi-spikes of soliton molecules (SMs) are experimentally achieved in a fiber laser with a dualcavity structure, respectively. The generation of NLSM owes to the intrapulse interference within an NLP or interpulse interference between two NLPs, exhibiting its coherence varying from weak to strong. Moreover, the coherent pulse spacing within NLSMs can change from 8.42 to 44.93 ps by altering length differences between two subcavities. Our work provides a novel approach for manipulating low coherent pulse generation.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293527 (2023) https://doi.org/10.1117/12.3007565
We propose a novel approach for the automated reproduction process of mode-locked pulse generation in a fiber laser, employing a statistical correlation analysis algorithm to execute rapid spectrum searching and matching. Our system incorporates a servo-based automatic control strategy to realize precise reconstruction of specific mode-locked states from white noise in accordance with desired spectral characteristics. The average reproduction time is 70 ms for a similarity, defined by the percentage error between targeted and matched spectra, of 98.96%. Consequently, our real-time reproduction algorithm offers a highly promising method for the automated manipulation of mode-locked pulse generation in laser industry.
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Xiaokang Li, Dong Li, Zhipeng Zhao, Yajun Jiang, Dingyi Feng, Wei Li, Deng Pan, Congjing Hao, Defeng Liu, et al.
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293528 (2023) https://doi.org/10.1117/12.3007567
In terahertz (THz) time-domain spectroscopy, the excitation of THz waves by fiber optic transmission of femtosecond pulsed lasers can provide great convenience for nondestructive testing of large and medium-sized aircraft. However, due to the high peak power characteristics of the femtosecond laser, the pulse spreading and distortion caused by fiber dispersion and nonlinearity can seriously affect the output laser pulse quality and the excitation of THz waves. In this paper, a three-segment femtosecond laser transmission scheme using asymmetric dual-core fiber (ADCF)-single-mode fiber (SMF)-dispersion-compensated fiber (DCF) is proposed. The simulation study results show that the strong dispersion using a 2.8-cm-long ADCF can reduce the 1 kW peak power to 8.03 W and extend the 50 fs pulse width to 3.74 ps, respectively. The spreading pulse can be restored to the peak power of 987.20 W and pulse width of 51.80 fs after the 10m-long SMF and then transmitted by the 66.9 cm-long DCF. This shows that the proposed femtosecond laser transmission scheme can achieve good pulse recompression and simultaneous recovery of pulse waveform and power, which lays the foundation for the construction of further THz time-domain spectroscopy systems using longer fibers for femtosecond laser transmission.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293529 (2023) https://doi.org/10.1117/12.3007570
Ultraviolet communication, as a new type of communication, has the advantages of strong anti-interference ability, non-line-of-sight(NLOS), and all-weather operation, so it has been emphasized and become one of the research focuses in the field of wireless communication. And the light source beam angle directly determines the distance and performance of communication, but most of the current studies are limited to simulation to analyze the influence of the beam angle. In this paper, in order to verify the effect of light source beam angle on the performance of line-of-sight(LOS) and NLOS communication systems, four types of collimator lenses for controlling the light source beam angle are designed and molded, and comparative analyses of simulations and measurements are carried out. The result shows that in LOS communication, the smaller the beam angle is, the better the system performance is. In NLOS communication, the change of beam angle has less change on the path loss and almost no effect on the system performance. The conclusion are of guiding significance in promoting the practical application of ultraviolet communication.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352A (2023) https://doi.org/10.1117/12.3007574
A physical model of the Littman configuration external cavity diode laser is established based on the angular spectrum theory, and the external cavity transfer function is derived. The wavelength-dependent coupling efficiency is calculated, obtaining the external cavity filtering envelope. Based on this model, we numerically simulate the filtering envelope with different parameters. The simulation shows that the filtering bandwidth of the external cavity narrows with the decrease of the collimator focal length. The wave aberrations of the collimator lens seriously degrade the peak reflectivity and filtering bandwidth of the external cavity. The impact of the external cavity length and the beam misalignment on the filtering function is studied, providing a theoretical basis for the error analysis of the optical path design.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352B (2023) https://doi.org/10.1117/12.3007580
Multi-Frame Blind Deconvolution (MFBD) algorithm is the mainstream post-processing method for atmospheric turbulence degraded images. The restoration of a single object from multiple images requires several minutes or even tens of minutes, which severely limits MFBD’s practical application. To achieve the goal of fast restoration, this paper proposes hybrid MPI-CUDA (Message Passing Interface-Compute Unified Device Architecture) accelerated MFBD algorithm. In this hybrid programming model, MPI is responsible for assigning computing tasks, and CUDA is responsible for parallel computing. Hybrid MPI-CUDA accelerated MFBD algorithm has been tested on simulated images and achieved satisfactory results. The execution speed for restoring a single high-resolution image from multiple blurred images has been increased by over 50-fold.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352C (2023) https://doi.org/10.1117/12.3007583
In order to solve the problems of fiber nonlinear effects due to constellation expansion and the reduction of information entropy due to constellation shaping, an 8-dimensional trellis coded 16-quadrature amplitude modulation format with probabilistic-geometric joint shaping (8D-TCM-PS-GS-16QAM) in high-speed optical communications is proposed. The BER performance of 8D-TCM-PS-GS-16QAM signals with unshaped, geometrical shaping only, and probabilistic-geometrical joint shaping (H=14/13/12 bits/symbol) is simulated. At a BER of 3.8e-3, the four shaped signals are able to obtain a gain of 0.36dB, 1.52dB, 2.02dB, and 2.46dB, respectively, compared with the unshaped signal. The BER performance of low-dimensional, i.e., 2D and 4D signals is also simulated. Comparing the gains obtained for 8D-TCM-PS- GS-16QAM (H=14 bits/symbol), 4D-TCM-PS-GS-16QAM (H=6 bits/symbol), and 2D-TCM-PS-GS-16QAM (H=2 bits/symbol) with the unshaped signals in the corresponding dimensions, the gains obtained at 3.8e -3 BER, are 1.52 dB, 2.29 dB, and 4.16 dB, respectively. Constellation shaping causes all three to sacrifice the same total information entropy of 1bits/symbol, but the information entropy sacrificed by the basic 2D constellations of the 8D signal is only 50%, 25% of that of the 4D and 2D signals. Meanwhile, the shaping gain obtained by the 8D signal reaches 66.4% and 36.5% of the 4D and 2D signals, respectively. This scheme enables the whole scheme to flexibly adjust the spectral efficiency (SE). Meanwhile, it increases the degree of freedom of the signal. This scheme can realize high BER performance transmission of high SE signals. It has great potential for future construction in high-capacity and high-speed optical communications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352D (2023) https://doi.org/10.1117/12.3007610
In contemporary film and television production, LED screens are commonly used as dynamic backgrounds, but moiré problems are often encountered. Existing studies on moiré control predominantly employ pre- or post-production removal methods, which exhibit limitations when applied to high technical specification images. To avoid moiré during the on-set shooting, cameramen often resort to techniques such as defocusing, the effect of which relies much on experience and expertise, and cannot entirely exclude the persistent occurrence of moiré phenomena in defocused scenarios. To address these issues, a more quantitative comprehension of the factors governing moiré formation is imperative. Previous explanations such as interference superposition of gratings or undersampling have proven inadequate in accurately simulating moiré on LED screens and therefore cannot effectively guide practice. We propose a convolutional imaging calculation-based approach for simulating the moiré pattern observed in screen shots. The simulated results exhibit consistent global patterns of moiré and their variation trends with shooting parameters, as compared to live results. We compare the moiré images generated through simulation methods with those obtained from live shooting experiments, while investigating the influential factors of moiré control during the live shooting. For various focusing scenarios, we present a constraint inequality for the shooting parameters, and demonstrate its efficacy in accurately predicting moiré reduction during defocused screen shooting. Furthermore, we apply this method to quantify the impact of camera roll rotation, LED screen dot pitch, opening ratio and pixel arrangement on moiré formation.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352E (2023) https://doi.org/10.1117/12.3007622
We present an equivalent circuit model for a silicon microring modulator (MRM), aiming to accurately describe its behavior in high-speed modulation. The model consists of two parts: the first part accounts for electrical parasitics arising from PN phase shifters and pads, while the second part represents the RLC circuit responsible for capturing optical dynamics of MRMs. Model parameters were derived through curve fitting, utilizing Si MRM characterization data. At data rates of 80Gb/s and 106Gb/s, simulated eye diagrams align perfectly with measured eye diagrams. The equivalent circuit model can be effectively used for electronics and photonics co-design.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352F (2023) https://doi.org/10.1117/12.3007632
In order to bring frequency combs out of well-controlled laboratory environments, a robust mode-locked fiber laser is preferable with enhanced self-starting capability, and reduced size, weight, and power (SWaP). We try to reduce cavity loss as much as possible to lower the self-starting threshold and operation power. A lower concentration doped-fiber could restrain non-radiative transitions and scattering from color centers, which are two main loss sources of active fibers. We performed comparison experiments using two fibers with different rare-earth doping concentrations for better SWaP performance. Experimental results match with our predictions. Pumped by a 980nm semiconductor external-cavity stabilized diode laser, a mode-locking self-starts at about 60mW. The net-dispersion is managed by balancing the lengths of the positively dispersive Er-doped fiber with the negatively dispersive PM1550 fiber. It is worth noting that the passive mode-locking can be maintained with pump power as low as 30mW. The laser central wavelength is 1560nm and 3db bandwidth is about 42nm, corresponding to a transform-limited pulse duration of 61.43fs assuming sech2 pulse shape. The repetition frequency is 47.41MHz with more than 90dB signal-to-noise ration at 1KHz resolution bandwidth. At the minimum pump power, the laser output is at 4.2mW average power.
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Hongwei Gao, Xiaoning Hu, Zhongming Yang, Zhaojun Liu
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352G (2023) https://doi.org/10.1117/12.3007637
Aiming at the characteristics of vortex beam and plane wave interference, as well as vortex beam self-conjugate interference, this report presents methods for microscopic displacement measurements using petal-like interferograms of vortex beam interference, which has been validated by theoretical analysis, simulations and experiments. On the basis of verifying the linear relationship between interference fringe Angle and micro-displacement through experiments, further, the information processing of petal-like interferogram is explored, and the corresponding fringe extraction method and error correction method are proposed, which provides a new detection scheme and technical approach for eddy light interference detection to be applied to nano level micro-displacement measurement.
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Shilin Chen, Tao Pu, Li Wang, Jilin Zheng, Gengze Wu, Jin Li
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352H (2023) https://doi.org/10.1117/12.3007643
The integrated mutual injection laser consists of a front section laser (FSL), a phase-section laser and a rear section laser (RSL). By adjusting the current of the two DFB lasers, the cavity modes of the FSL and RSL coexist in a period-one (P1) state, and the integrated laser is a dual-mode output. The beat frequency (fLO) can be obtained as the optical local oscillator (LO) frequency. When the linear frequency modulation (LFM) signal is directly modulated onto the front section laser of the integrated laser, after passing through the photodetector, the two main oscillation modes will beat with the first-order optical modulation sideband of the other mode, thereby generating the new frequency signals (fLO±fLFM). When the fundamental frequency signal or fLO is tuned, a double chirp signal with opposite chirp rate can be generated in different frequency ranges. In the simulation experiment demonstration, DCMWs in the frequency range of 11~17 GHz and 5~9 GHz are obtained respectively, and the corresponding time bandwidth product (TBWP) reaches 800. The full width at half maximum (FWHM) can reach 0.272 ns, and the peak sidelobe ratio (PSR) can reach 21.45 dB. The scheme is beneficial to further enrich the transmitting frequency band of radar detection signal. The principle is simple, the integration is high, the operation is convenient, and the frequency is adjustable.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352I (2023) https://doi.org/10.1117/12.3007646
Gratings, as important optical elements, are widely applied in the field of optical metrology as well as spectral purity. With the gradual decrease in the measuring wavelength to ensure high sensitivity, the scalar diffraction model has once again gained attention as a fast method for obtaining diffraction results and analyzing physical processes. This paper provides a detailed deduction of the reflected diffraction efficiency of an asymmetric trapezoid grating using the scalar diffraction theory, and demonstrates its validity and accuracy by comparing it with the vector diffraction theory. Building upon the scalar model, we further developed a rapid reconstruction model to determine the grating structure using an intelligence optimization method, namely an improved particle swarm optimization algorithm with random perturbation. The method eliminates the need for creating a large dataset for model training, while still providing a relatively accurate measurement result. It can be seen as a step towards narrowing the search range of feasible solutions, which significantly improves the efficiency of metrology.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352J (2023) https://doi.org/10.1117/12.3007650
A cost-effective 46.9 W diffraction-limited all-fiber laser at 980 nm was demonstrated with a 20/80-μm octagonal double-cladding Yb-doped fiber under direct pumping of low-cost 915 nm laser diode. The slope efficiency is about 24% and the center wavelength is 977 nm. The beam quality M2 factor is measured to be 1.30 (Mx2 = 1.40, My2 = 1.19). The amplified spontaneous emission at 1030 nm is about 50 dB lower spectrally at the maximum output power. To understand the laser generation process and optimize the output performance, we investigated the effect of gain fiber length on the output power characteristics both experimentally and theoretically. The experimental results are consistent with the simulation.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352K (2023) https://doi.org/10.1117/12.3007651
In solving the problem of random launch of long-distance and high-precision strategic missile trains, the passive autonomous navigation mode dominated by inertial navigation (INS) shows its unique advantages, but the Inertial navigation system has the problem that the accumulated error cannot be eliminated, which cannot meet the practical application requirements, and needs to be assisted by other navigation means. As a passive and fully autonomous navigation system, geomagnetic navigation has the advantages of low cost, anti-interference, all region, small size, and no accumulated error, which can effectively compensate for the shortcomings of other current navigation systems. In this paper, we introduce high-precision laser Doppler velocimeter (LDV) and geomagnetic sensor into the integrated system, and propose a geomagnetic sensor assisted INS/LDV integrated positioning scheme. On the basis of INS/LDV integration, we design INS/LDV/geomagnetic sensor integrated navigation system and algorithm, correct the error of NS/LDV integrated navigation system, and further improve the integrated navigation positioning accuracy.
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Kan Huang, Yanwei Huang, Zehang Xu, Siyuan Yu, Ruijun Wang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352L (2023) https://doi.org/10.1117/12.3007652
Quantum cascade lasers (QCLs) are semiconductor lasers that generate photons through intersubband transition in quantum well structures. Nowadays, QCLs can cover the mid-infrared wavelength range, making them excellent for sensing and spectroscopy. In the last decade, it is found that QCLs can directly output frequency modulated frequency combs due to the four-wave mixing process introduces a large nonlinearity into the cavity. Flat and slightly negative group velocity dispersion (GVD) are favorable for the generation of frequency combs in QCLs. Therefore, many efforts have been devoted to engineer the dispersion of the QCL cavity in recent years. In this paper, we propose the use of silicon photonic integrated circuits as a dispersion compensation scheme for QCLs. The light from the QCL is coupled to the silicon-on-sapphire (SOS) waveguide through butt-coupling. A loop mirror consisting of coupled SOS waveguides is employed to provide the optical feedback and dispersion compensation. The antisymmetric super-mode of TM0 and TM1 in the coupled waveguides are selected to compensate the positive GVD (~1000fs2/mm) of the QCL. This numerical study paves the way to hybrid integration of QCL frequency combs with silicon photonics integrated circuits.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352M (2023) https://doi.org/10.1117/12.3007656
Draw tower grating (DTG) with large capacity, long distance, fast response and other advantages is rapidly becoming the current mainstream fiber optic sensors, but want to write high reflectivity fiber on the draw tower fiber is particularly difficult. Therefore, it is important to further study the grating formation mechanism of fiber gratings for the rapid preparation and wide application of DTG. We will four different types of pure silicon dioxide optical fiber core fiber and G654E bend-resistant fiber for multi-pulse writing experiments. In pure SiO2, due to the lack of oxygen conditions Si-O-Si structure in the middle of the position of the oxygen atom will produce neutral oxygen vacancies, when the capture of a positively charged hole will form a SiE' color centred, while the experimental results of two pure dioxide optical fiber and can not be inscribed out of the grating, indicating that defects in the optical fiber is not a defect in the color centred is not a necessary condition for the formation of optical fiber into the grating. In order to further investigate the role of the color centred on the refractive index modulation of optical fibers, the above fiber for high-pressure hydrogen-carrying experiments, the hydrogen-carrying fiber for the multi-pulse writing experiments, found that there is still a pure dioxide optical fiber can not be written into the grating, and the remaining four types of optical fiber emissivity have a greater increase, to verify that the color centred model of the refractive index modulation of optical fibers is not a direct contribution to the indirect.
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Gangwei Wang, Xiuping Zhang, Junyong Zhang, Cheng Liu
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352N (2023) https://doi.org/10.1117/12.3007658
Diffraction lens had been widely used in the field of super-resolution imaging, laser dicing, and particle trapping. Although Greek-ladder photon sieves is a kind of amplitude-only diffraction lens and suitable for EUV and soft x-ray focusing and imaging, the focal length are hard to be measured precisely by non-destruction testing due to its fine feature. Here quasi-Walsh phase retrieval is proposed to measure the focal length in one-single exposure. Compared to the random scatter plate, a quasi-Walsh phase plate can not only greatly decrease the alignment precision, but also provide the unique solution of the test wavefront. Simulation experiments show that the proposed single-shot Walsh-modulation phase retrieval can measure the focal lengths of the Greek-ladder photon sieves with high precision, which can greatly facilitate the development of multi-focal diffraction lens.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352O (2023) https://doi.org/10.1117/12.3007666
Some people utilize micro-cameras to spy upon other people or important confidential items. This kind of behavior severely affects people’s privacy securities and government’s intellectual safeties. Micro-cameras, however, are hard to be recognized by human eyes and do not spread any signals or radiations. This paper analyzes the basic principle of the cateye effect and states its advantage by applying the cat-eye effect on micro-camera detection. Furthermore, the activedetection model based on cat-eye effect is analyzed in this paper in order to explore the relationship between the detection efficiencies of micro-cameras and the incident angles of the laser beam to the micro-cameras. By applying the knowledge of geometric optics and wave optics, the specific structure of a micro-camera and spectral characteristics of reflections are analyzed. This study calculates and simulates the echo light field with different incident angles at a certain detection distance. Based on the physics model, an active detection system is set up. The experiment results prove the feasibility of utilizing the cat-eye effect to detect micro-cameras; in addition, the intensities of the diffracted light fields decrease with the increase of incident angles, and it is still effective within 10 degrees of the incident angle. The experimental results and mathematical analysis verify the reliability of the detection effect at different incident angles.
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Mengliang Xu, Yi Xie, Ting Chen, Jie Zhang, Manchao Zhang, Wenbo Su, Xieqian Li, Ting Zhang, Wei Wu, et al.
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352P (2023) https://doi.org/10.1117/12.3007674
We have developed fast and accurate protocols for ion shuttling in a surface-electrode ion trap, which allows efficient splitting and merging of two ions. These protocols are based on innovative improvements in the driving potential field model, where voltage is introduced as a variable parameter. This enhancement specifically addresses the issue of increased control errors that occur with larger inter-ion distances. We have devised a general model-solving procedure that uses a parameterized model to describe the total potential energy of the two ions and ions oscillating eigenfrequency in a dynamical normal modes. By employing optimization techniques, we determine optimal voltage ramps for the dynamic potential field, enabling accurate control of physical quantities during the splitting process. In additionally, through simulating the classical dynamics of the theoretical scheme, we decouple the ion oscillations by employing discrete Fourier transform (DFT) and nonlinear fitting techniques. Two ions are separated into individual potential wells with a distance of 200 μ𝑚 within 50 μs. The ion position drift is only 0.01%. During the splitting process, the frequency fluctuation of the center-of-mass mode of the ions is less than 0.69%, and the minimum average excitation of a single ion is 0.02 phonon. Accurate and fast ion shuttling technology facilitates the development of large-scale trapped-ion quantum computing. Maintaining the ions oscillating eigenfrequency constant during the shuttling operation alleviates the problem of decoherence of quantum information.
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Ruiguang Yin, Lin Gan, Qianrong Chen, Guangsen Ren
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352Q (2023) https://doi.org/10.1117/12.3007676
The hardware-in-the-loop simulation is widely used in laser semi-active guidance test, the accuracy and fidelity of diffuse laser signal is the key problem for simulation credibility. Due to the limitations of the simulation method and devices, the total energy and distribution of simulating laser had some errors, the advantage and disadvantage of laser energy attenuation methods should be judged. Combining calibration, predication and experiments, a feasible method to control laser energy attenuation was proposed. By comparing the different energy distribution state between actual condition and hardware-in-the-loop simulation, the influence mechanism of laser seeker was obtained. In conclusion it was pointed out that the different between simulation system and actual system has little influence on laser guidance. The research is helpful to design and evaluation of laser guidance simulation system.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352R (2023) https://doi.org/10.1117/12.3007682
A quadrant detector (QD) is a widely used position sensor. By employing ghost imaging, the detector's four-channel output can be multiplexed to simultaneously locate and image a target. However, flaws in the detection system distort the detected laser intensity, which will increase positioning errors and degrade the reconstructed image quality. In this study, based on the spot distribution and detector characteristics, a detection model was established and analyzed. A neural network-based fitting method is proposed to directly predict the spot location and correct the total light intensity with the detector output. The network is constructed and trained with simulated data. The prediction accuracy performance is verified by numerical simulations. This scheme has the potential to improve the localization accuracy and imaging quality of quadrant detector-based detection systems, such as radar and guidance applications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352S (2023) https://doi.org/10.1117/12.3007686
Dynamic light scattering is often used to detect small particles, such as in industry and medicine. A typical ill-posed problem needs to be solved to recover PSD by inverting ACF data , which is a difficult problem of DLS. when DLS is used for detecting small particles in transformer oil, it is difficult to accurately recover PSD using traditional algorithms. Generalized regression neural network(GRNN) has been proved to be applicable to solving ill conditioned equations in Dynamic light scattering method. However, accurate inversion relies on proper training sets closely matching measured particle size to avoid large errors. Generating numerous samples for multimodal distributions is time-consuming. This study investigates how sample setting range affects GRNN inversion accuracy during training.The experimental system was self-built, using 362.2nm and 806.9nm polystyrene mixed diluted lotion as selected samples. The training sets were centered around theoretical particle sizes, with range variations of 10nm, 30nm, 50nm, and 100nm. The GRNN was trained using these sets, and the experiment’s light intensity autocorrelation data was input into the neural networks to obtain particle size distributions and bimodal peak particle sizes. All the sample set were achieved by measuring ACF of 362.2nm and 806.9nm polystyrene suspension on a self-built DLS experiment system. These findings indicate that closer proximity between the sample range used in neural network training and the actual situation leads to more accurate inversion results, demonstrating the network’s ability to accurately invert bimodal samples. Furthermore, the accuracy improves with more realistic training set settings. In practical measurements, combining regularization methods with this approach can enhance particle size analysis accuracy.
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Yi Sun, Xinya Liu, Xiaofei Wang, Tao Meng, Xiaolei Zhang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352T (2023) https://doi.org/10.1117/12.3007687
One of the key components of a belt conveyor, the conveyor belt, often operates in challenging environments and is prone to longitudinal tearing faults. In order to promptly detect longitudinal tearing faults in conveyor belts and minimize the losses caused by such failures, this paper proposes a visual defect detection system assisted by line laser technology. This system employs an industrial camera to capture images of the conveyor belt's underside illuminated by a line laser. Initially, the images are preprocessed, and a hierarchical pyramid-shaped model with a level of 1 is established for matching purposes. A portion of images depicting conveyor belts without longitudinal tearing is used for training to generate a shape template. Once the template is created, it is employed to detect anomalies in the images under examination. When a comparison between the test image and the template surpasses a predefined threshold, anomalies are identified and marked, allowing for an effective determination of whether the conveyor belt is torn.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352U (2023) https://doi.org/10.1117/12.3007689
This study proposes a physical layer encryption scheme for coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems utilizing index permutation based on the M-ary bit reversal mechanism using chaos. The original signal's bit data is subjected to comprehensive bit scrambling within the bit domain for OFDM signals, accomplished through a series of operations including adaptive filling, bit reversal, and suffix addition, all driven by three keys generated from two random chaos systems. To assess the effectiveness of this enhanced security scheme, a simulation is carried out on a 16QAM CO-OFDM system with a net data rate of 213 Gb/s, operating in a back-to-back (BTB) transmission configuration. The results unequivocally demonstrate the system's robust security performance, with an unauthorized user unable to extract any meaningful information, as evidenced by a bit error rate (BER) of 0.5. The key space is up to 10120, which indicates the strong resistance to attack for encryption system. Additionally, the maintained peak to average power ratio (PAPR) illustrates that the proposed physical layer encryption scheme can preserve good system performance during the enhancement of security.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352V (2023) https://doi.org/10.1117/12.3007690
A simple, low-cost and new all-optical photoacoustic droplet microfluidic detection system is proposed by combining the pure optical photoacoustic detection technology based on polarized light reflection with droplet microfluidic chip technology. In this work, we first use Matlab and Comsol to carry out theoretical calculation and simulation of polarized light reflection, the theory and simulation results are highly consistent. In the experiment, a simple and practical microfluidic chip was prepared by the molding method, and the application range of the polarization based pure light photoacoustic microfluidic detection technology was expanded. Firstly, the photoacoustic signals of black tape in microfluidic chips with different pipe heights are tested to verify the feasibility of our system. Then the suitable flow rate and the flow rate ratio of the two-phase flow were adjusted, and a large number of homogeneous droplets were generated. Methylene blue as one of the samples, the photoacoustic signal of methylene blue droplets was detected. The results show that the polarized light based total internal reflection optical system combined with microfluidic chips has great application potential in microfluidic detection.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352W (2023) https://doi.org/10.1117/12.3007691
Antimony laser diodes emitting at 2 μm have shown great potential due to the extraordinary performance in gas detecting and other promising fields. However, it is difficult to increase the power of antimony laser diodes, the applications of which would be restricted greatly. In this paper, we report the watt-level antimony laser diodes emitting at 2 μm developed by our group, and the maximum output power can achieve about 1.082W at 20℃ with the injection current set as 5A, showing excellent performance.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352X (2023) https://doi.org/10.1117/12.3007694
The uneven distribution of seawater results in continuous attenuation of the beam during the transmission process due to the absorption and scattering effects of water. Additionally, the scattering effect causes a multipath effect that produces inter-symbol interference in the communication mode, which can significantly impact the system performance. In this paper, the inherent optical scattering characteristics of underwater channels were analyzed, and a Geometric scattering model of a single particle was developed for underwater laser communication (UWOC) systems with non-line-of-sight. The scattering phase function was based on the characterization of forward and backward scattering. The paper also derived the expression of the underwater channel impulse response based on the scattering phase function that characterizes forward and backward scattering. Moreover, the validity of the underwater photon transmission channel model was verified using Monte Carlo (MC) simulation in different water environments. The simulation results of the MC channel impulse response in coastal waters were found to be better than the theoretical ones. The paper proposed two algorithms, namely linear equalization and decision feedback equalization, based on functional neural network (FLANN), to suppress inter-symbol interference. These algorithms were applied in multiple phase shift keying modulation to improve the transmission performance. The results showed that the bit error rate performance of decision feedback was better than that of linear equalization, indicating its potential to effectively improve the transmission performance of UWOC systems.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352Y (2023) https://doi.org/10.1117/12.3007702
Microwave photonics offers a promising solution to the increasing demand for high-frequency and broadband signals in battlefield communications. We propose a method for receiving broadband microwave signals with image-reject processing. The approach involves two main processes: signal reception and image-reject processing. In signal reception, the input broadband signal with a frequency span from DC to 40 GHz is multicast to three-tone signal optical carriers using a Mach-Zehnder modulator (MZM) biased at its minimum transmission bias point (MITB). Then, by using a three-tone local oscillator (LO) optical carriers to align with the corresponding modulation sidebands of the signal optical carriers, the input signal at any center frequency and with a bandwidth of 10 GHz can be demodulated after one capture. Hence, the full bandwidth of 40 GHz can be received by capturing the signal four times. In image-reject processing, the modulation sidebands of the signal carriers and the corresponding LO carriers are injected into an optical coherent receiver to achieve IQ demodulation. The generated in-phase (I) and quadrature (Q) signals are digitized and processed to suppress image interference. A numerical simulation is carried out to validate the proposed scheme. The simulation result indicates that the proposed scheme is capable of receiving broadband signals with a bandwidth of 40 GHz and its instantaneous bandwidth is equal to 10 GHz. Besides, the sensitivity and the dynamic range of the proposed system are equal to -85 dBm and 109.9 dB·Hz2/3, respectively. The proposed scheme is promising for enhancing the receive bandwidth and the sensitivity in electromagnetic spectrum sensing applications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129352Z (2023) https://doi.org/10.1117/12.3007704
Free-form curved optical elements have problems such as high degree of freedom of the surface shape, large surface gradient changes, requiring precise sample position adjustment before the measurement, which limits the accurate measurement of the surface shape. In order to address these problems, this paper proposes a laser confocal free-form surface profile measurement method based on the Adaptive Ant Colony Algorithm. This method utilizes the fact that the peak of the laser confocal axial response curve corresponds to the focal point of the sensor and that the peak position is not affected by changes in the tilt angle of the surface to be measured, thus realizing high-precision measurements of the three-dimensional morphology of free-form surfaces with large tilting angles. This method establishes the matrix transformation relationship between the coordinate system of the freeform surface measurement system and the design equation, and realizes the in-situ preliminary pre-alignment of the free-form surface by constructing a nonlinear least squares objective function. Then, through the Adaptive Ant Colony Algorithm, the optimal solutions of the six parameters in the transformation relation are globally searched, and the high-precision tracking measurement of the measured free-form surface is achieved. We constructed a high-precision free-form surface measurement system, and experimentally verified the laser confocal free-form surface measurement method based on the Adaptive Ant Colony Algorithm proposed in this paper. The results of the aspheric surface measurement test show that the repeatable measurement accuracy of the asphere surface shape residual PV99 is better than 50nm, the repeatable measurement accuracy of the residual RMS is better than 15nm, demonstrating the high iterative alignment accuracy of the Adaptive Ant Colony Algorithm. Therefore, our method provides an effective means of high-precision measurements of free-form surfaces.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293530 (2023) https://doi.org/10.1117/12.3007705
In our work, we experimentally demonstrate wavelength multiplexed dual-comb pulses based on multi-modal interference effect in a passively single-walled carbon nanotube mode-locking all fiber ring laser. The laser cavity achieves a variety of dual-wavelength mode-locked states by switching the polarization controller in the laser cavity. A piece of 25 cm long graded-index multi-mode fiber as a filter based on the multi-mode interference effect is introduced into cavity to fixing wavelength and to improving the signal to noise ratio. With optimized length of multi-mode fiber, we observed the two different filter state which located at 1559 nm and 1562 nm, 1561 nm and 1563 nm respectively in the different polarization dual-comb states. With suitable filtering state by stretching the multi-mode fiber, the two asynchronous pulse sequences coexist with diverse operation, which propagate with singlet and double pulses, respectively. The repetition rate of the laser is 16.59 MHz and the time period corresponding to the asynchronous pulse is ~60 ns. The repetition rate difference of dual-wavelength states reaches 100 Hz. In addition, we recorded the output modulation state of the laser cavity. Our research provides experimental basis for optical fiber sensing, wavelength division multiplexing communication system and high resolution spectroscopy.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293531 (2023) https://doi.org/10.1117/12.3007706
Autofocus optical imaging systems are widely used in industrial inspection, medical diagnosis, drone photography, machine vision and other fields. Image-based autofocus algorithms typically consist of two key steps: image sharpness evaluation and search strategy. In this study, we propose an advanced image-based autofocus algorithm specifically designed for industrial image measurement. In order to improve the accuracy of the clarity assessment, we improve the existing method by introducing Gaussian filtering and threshold controlled Laplace operators. This improvement effectively reduces the effects of noise and light intensity changes, improving the reliability of clarity measurements. In addition, we propose a novel distance adjustment strategy combining coarse and fine tuning as part of the search strategy. This strategy reduces the interference of local peaks, allowing the algorithm to accurately identify the best image focus. The proposed image-based autofocus algorithm has several advantages, e.g. high focusing accuracy, high repeatability, and stability under light intensity changes. These advantages make it ideal for industrial image measurement applications. To verify the effectiveness of our method, we build an experiment setup in a lab using ADLINK PCI-9114-DG board and a custom-designed lens. The results show that the sensitivity and performance of the autofocus system meet certain requirements. In summary, the image-based autofocus algorithm that we developed enables accurate and reliable focusing. It overcomes some challenges such as noise and light intensity changes to ensures optimal image focus, and improves overall image quality. The successful implementation of our autofocus system can benefit industrial inspection, medical diagnostics and many other applications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293532 (2023) https://doi.org/10.1117/12.3007707
Although the optical access network based on industrial IoT can provide large connections and high bandwidth for smart factory construction, it still lacks an effective guarantee in information security transmission and control and is difficult to cope with new challenges such as accelerated penetration of security threats and complex and diverse attack methods. To ensure the secure authentication transmission of the devices connected to the optical access network in the smart factory, an automated assembly line with a trusted chain of ”host computer - trusted security controller” in the industrial IoT scenario is designed, the core of which is a trusted industrial controller with both a host system and a trusted subsystem, in which the trusted subsystem is encapsulated with self-designed SHA-2 based bi-directional verification integrity metric algorithm, which dynamically measures the integrity of system firmware and project files, and has active control logic to control the start-up behavior of the host system based on the integrity metric results while using a digital signature to transfer the trusted chain to the host computer. We have verified the cold start time, integrity metric rate, and attack resistance of the trusted industrial controller, and the experiments show that the controller has better usability with a cold start time of fewer than 60 seconds, integrity metric rate >1MB/S, and better attack resistance than the non-trusted controller.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293533 (2023) https://doi.org/10.1117/12.3007726
In order to solve the problem that the severe inter-symbol interference (ISI) introduced by faster-than-Nyquist (FTN) strong filtering leads to the degradation of the equalization capability of the traditional receiver side (Rx) IQ imbalance compensation, a two-stage Rx IQ imbalance compensation algorithm is designed and demonstrated in this paper. The algorithm uses a time domain equalizer based on the decision directed-least mean square (DD-LMS) algorithm cascaded with a 4×2 frequency domain (FD) equalizer based on the radius directed equalization (RDE) algorithm, which can effectively improve the compensation range compared to using only a conventional 4×2 FD equalizer based on the RDE algorithm. 128Gbaud-FTN-PM-16QAM system simulation results show that with an acceleration factor as low as 0.85, the designed algorithm has a 14.3%, 100% and 40% improvement in the compensation range of Rx IQ amplitude, phase and skew imbalance compared to using only the 4×2 FD equalizer based on the RDE algorithm. The results validate the performance improvement of the proposed algorithm.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293534 (2023) https://doi.org/10.1117/12.3007730
This paper analyzes the principle and process of laser detection and scattering interception for typical laser detection instruments, and lists the dominating factors that may affect the ability of laser detection and scattering interception. Based on Mie scattering theory, the calculation model of laser detection scattering interception is established, it can be used to calculate the scattering laser power intercepted by laser detection instruments under different conditions. The dominating factors, such as sensitivity, atmospheric visibility, laser power, laser transmission distance and transmission elevation, are simulated and analyzed with the model to get the influence on laser detection and scattering interception in sequence. According to the simulation results, the relationship curve is drawn, and the changing law of laser detection and scattering interception ability under different factors is obtained. This paper provides a useful technical reference for the configuration and optimization of laser detection instruments in different scenarios.
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Xinya Liu, Yi Sun, Xiaofei Wang, Tao Meng, Xiaolei Zhang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293535 (2023) https://doi.org/10.1117/12.3007734
In binocular stereo vision, stereo matching is a critical technique that has always been the focus and challenge of research in the field of stereovision. The results of stereo matching directly impact the effectiveness of 3D reconstruction. Due to the limitations of traditional region-based local stereo matching algorithms, which rely solely on similarity measure functions using information such as grayscale, color, and gradient from a point's neighborhood to compute matching costs, these algorithms have lower computational complexity. This can lead to problems such as incorrect matching in areas with repetitive textures, weak textures, and depth discontinuities. Therefore, building upon traditional region-based local stereo matching algorithms, this study investigates a global stereo matching approach based on dynamic programming. This method employs global constraint information from the image and constructs a global energy function for matching costs. Leveraging the principles of dynamic programming and stereo rectification, the approach decomposes the process of solving the entire image disparity into several subprocesses, solving them sequentially. The specific process involves adhering to the order of epipolar lines, seeking the minimum cost path on the disparity image, and obtaining the final disparity map. As the global stereo matching algorithm based on dynamic programming considers the disparity constraints between pixel points along epipolar lines, it can effectively address mismatching in depth-discontinuous areas and regions with uniform textures, yielding favorable outcomes.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293536 (2023) https://doi.org/10.1117/12.3007735
The microscopic fringe projection profilometry system using a digital micromirror device (DMD) can improve the height sensing sensitivity by reducing the fringe pitch. However, due to the discrete nature of the DMD, it is impossible to apply arbitrary and continuous phase shifts when the fringe pitch is reduced to a few pixels. The proposed method uses a plane-parallel plate to produce a displacement on the light passing through it and achieves continuous phase shifts by controlling the oblique angle of the plate. Experimental results demonstrate that the proposed method can introduce continuous phase shifts to quasi-sinusoidal fringes with a minimum pitch of 2 pixels and correctly demodulate the phase map using a 9-step phase-shifting algorithm. Simulation and experiments also show that the inherent phase shift error can be neglected when the relevant parameters of the plate are properly selected.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293537 (2023) https://doi.org/10.1117/12.3007737
The implementation of IM-DD optical communication systems requires low cost, power consumption and latency, making low complexity and high real-time deployment potential digital signal processing (DSP) a critical component. The clock synchronization algorithm plays a crucial role in ensuring real-time deployment by eliminating sampling clock deviation at the transceiver and optimizing the signal sampling position. In this context, we proposed an enhanced clock synchronization scheme based on the classic Gardner algorithm, which effectively addresses the widespread timing jitter issue in the synchronization loop while maintaining computational efficiency. Through comparative experiments of multiple single-lane 112Gb/s PAM-4 IM-DD transmissions, we demonstrated that our clock synchronization scheme is capable of effectively compensating for the clock offset in a high-speed 100Gb/s+ IM-DD transmission system. Our experimental results show that the algorithm achieves a correction accuracy of 1 part per million level, which is comparable to the receiver sampling frequency in the transmission (GHz). Moreover, the importance of clock synchronization for IM-DD systems is also highlighted by comparing signal quality with and without the algorithm. Without an equalizer to compensate for signal degradation after using a clock synchronization algorithm, the constellation can still be obtained clearly. If not perform the clock synchronization, a clear constellation cannot be obtained even with an equalizer. This is manifested in the signal-to-noise ratio, which our clock synchronization algorithm can bring the improvement of more than 1 dB. Additionally, the bit-error-ratio can be improved by about 5 numerical levels under specific modulation amplitude.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293538 (2023) https://doi.org/10.1117/12.3007738
Optical vortex beams (OVs) possess an infinite number of orthogonal orbital angular momentum (OAM) states, making them highly beneficial for increasing communication capacity. In this work, a new type of power-exponent-phase-like vortex beam (PLB) with both quadratic and cubic changes in phase is investigated, and the two cases where the phase gradient increases or decreases along the azimuthal angle are analyzed. Furthermore, based on the changes in phase between 0 and 2π for the direction angle, the single-period and multi-period scenarios are discussed. Both simulations and experiments demonstrate that the intensity distributions are noticeably different when the gradient direction increases or decreases along the azimuth angle. Additionally, the OAM density, the orthogonality, and the OAM of these nonlinear beams are assessed. The intensity distribution of the PLB is not uniform along the angle direction, however, it offers a distinct orthogonality, and the total OAM remains constant, which provides new ideas for applications such as particle manipulation, optical communications, OAM encryption, and more.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293539 (2023) https://doi.org/10.1117/12.3007741
Electric field sensing has wide applications in electromagnetic compatibility, communication, electromagnetic radiation, wireless monitoring in aviation, et.al. With the development of precision devices, there is a growing need to measure weak electric field in complex environments. Traditional electric field sensors, due to the presence of multiple metal electrodes, often suffer from interference with the measured field, making it difficult to accurately measure weak electric field in space and unsuitable for narrow space field measurements due to their large size. In order to solve these problems, this paper presents a high-sensitivity electric field sensing chip based on lithium niobate material. The sensing chip adopts the Michelson interference for the sensing measurement of electric field. The sensor was designed for high sensitivity measurement at specific frequency. To demonstrate the versatility of the proposed solution, two target frequencies of 10 GHz and 12 GHz were designed to analyze the frequency response of various antenna parameters based on a tapered dipole antenna structure Based on the simulation. We fabricated electric field sensing chips with dimensions consistent with the simulation, parameters of dipole lengths 1.5mm and 2mm, and modulation electrode lengths of 4.4mm and 5mm were determined to fabricate the proposed chip. The fabricated chip size was 23.2mm × 4.6mm × 1.5mm. The experimental results demonstrated that the electric field sensing chips exhibited good linearity. Under the condition that the signal-to-noise ratio of 10dB, the measured sensitivities of the two sensing chips at their respective resonant frequencies were 41.6μV/m and 32.7μV/m.
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Jiamu Liu, Qi Zhang, Yi Cui, Fu Wang, Feng Tian, Qinghua Tian, Yongjun Wang, Leijing Yang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353A (2023) https://doi.org/10.1117/12.3007742
In this paper, a flexible extended Kalman filtering (EKF)/cubature Kalman filtering (CKF) switching scheme with fast frequency offset (FO) estimation is proposed to cope with the impairments due to FO and rotational state of polarization (RSOP) caused by lightning strikes in optical fiber communication systems. The fast FO estimation method based on statistics is introduced to compensate the residual FO after coarse estimation with fast Fourier transform (FFT). The aggregation of symbol angles is used as a statistical measurement of FO. The switchable Kalman filtering enables compensation for varied fast RSOP by mathematically modelling lightning strikes and automatic switching between EKF and CKF. The EKF compensates better under slow RSOPs and less well under fast RSOPs caused by sudden lightning strikes. Hence CKF is introduced to compensate for the fast RSOP after a sudden lightning strike. To achieve automatic switching between EKF and CKF, RLC high voltage charge-discharge model is introduced to emulate RSOP of lightning strikes and use EKF to track RSOP in time domain. The effectiveness of the proposed scheme has been verified in a 14 GBaud PDM-16QAM simulation system which effectively improve the FO and RSOP tolerance for optical fiber communication systems. The results show that the proposed fast FO estimation method can tolerate FO up to 800 MHz. The Bit Error Rate (BER) performance with different FOs also verified the effectiveness of the proposed scheme. The maximum speed of RSOP caused by lightning strikes compensated by CKF can reach up to 80 Mrad/s, while EKF is less than 70 Mrad/s. Moreover, the tracking parameter of EKF had a sudden change after lightning strikes which can be used to set the threshold to automatic switching between EKF and CKF.
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Jing Xiang, Ziqiang Meng, Jialong Zhang, Yukun Wan, Wei Li
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353B (2023) https://doi.org/10.1117/12.3007744
As a trace gas detection technique without background noise, the main advantages of photoacoustic spectrometry are high detection sensitivity and good stability, which can be well applied in various fields such as atmospheric environment monitoring, medical diagnosis, and industrial production monitoring. In this paper, a sweep frequency modulation method is used to acquire 8 sets of sweep frequency photoacoustic signals of acetylene gas at different concentrations from 1 ppm to 50 ppm. The swept signals are subjected to wavelet denoising and subsequent processing after passing through a lock-in amplifier. The wavelet base selected for wavelet denoising is sym4, the threshold function is set to soft threshold and heursure is selected, and the number of wavelet decomposition layers is 7. After wavelet denoising, the Lorentzian fitting of the swept curve is performed to extract the peaks, and the points that deviate from the curve and affect the accuracy of Lorentzian fitting are removed by a kind of pre-fitting and calculating the residuals between the actual data and the fitted data to set the threshold. The experimental results show that the prediction error of 1 ppm is reduced by 10.01% and 2 ppm by 2.17% after wavelet denoising, and the noise analysis of the system shows that the standard deviation of the signal is 1.1781 μV. The detection limit of acetylene gas is 936.5 ppb. The experimental results validate the feasibility of wavelet denoising in acetylene concentration detection based on swept frequency modulated photoacoustic spectroscopy.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353C (2023) https://doi.org/10.1117/12.3007753
We experimentally construct a polarimetric imaging architecture based on coherent lidar by using the frequency modulated continuous wave (FMCW) and the Risley prism beam steering technology for target identification. By combining coherent detection and multi-channel point cloud fusion, the proposed polarimetric imaging design is exploited to not only achieve the large-scale scene reconstruction in complex environments, but also distinguish the target from other objects with diverse structural materials or camouflage. An outdoor polarimetric imaging experiment which has an imaging scene of ±30° and an angular resolution of 0.1°, is also performed utilizing the proposed architecture. Furthermore, the structures with different polarization characteristics can be displayed by selecting different polarization parameter images, which greatly improves the information dimension of target identification. The polarimetric imaging architecture provides a multi-dimensional perception and open new opportunities for remote sensing, autonomous driving, and military reconnoitering.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353D (2023) https://doi.org/10.1117/12.3007756
Due to the multilayer structure of the extreme ultraviolet(EUV) mask, it is easy to produce defects during the fabrication of the EUV mask, resulting in the deformation of the multilayer and thus changing the optical characteristics of the mask. Detection of defects in the EUV mask is one of the challenges of EUV lithography. In this paper, simulation analysis of defect inspection by Fourier ptychography(FP) is performed. The defective mask blanks' aerial images at different illumination angles are simulated. The amplitude and phase of the aerial images are reconstructed using FP. The effects of light source bandwidth, the number of the multilayer, angular deviation, and imaging noise of the reconstructed aerial image are analyzed. The simulation results show that the loss of intensity and phase shift of the aerial images are different with illuminations of different wavelengths. The reconstructed amplitudes of the aerial images are affected by the wavelengths within the EUV bandwidth. The flatness of the top profile of the phase defect is the key factor affecting the aerial images of the mask. Appropriately increasing the number of the multilayer can reduce the loss of intensity of the aerial images. Excessive angular deviation will affect the reconstructed amplitude and phase of the aerial images. Gaussian noise with a specific Signal-Noise Ratio(SNR) reduces the accuracy of the reconstructed amplitude and phase of the aerial images.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353E (2023) https://doi.org/10.1117/12.3007763
Optical clocks have achieved remarkable levels of uncertainty and stability, leading to the possibility of redefining the second based on optical transitions in the future. Incorporating optical clocks into local time scales holds great potential for enhancing their performance. A simulation approach is employed to construct a time scale composed of a continuously operating active hydrogen maser (HM) and an intermittent 87Sr optical lattice clock (OLC), utilizing Kalman filter algorithm for steering. This study investigates the influence of various operational strategies for the OLC on the steered time scale performance. The simulation result shows that when running the OLC for 4 hours per day, the root-mean-square (RMS) of the time errors is less than 0.6 ns after 30 days, while the frequency stability of the time scale reaches mid-E-17@3×106 s.
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Junqi Yang, Xiuqing Song, Zhaoyong Wang, Yifan Liu, Luwei Shuai, Junxiang Zhao, Qing Ye, Haiwen Cai
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353F (2023) https://doi.org/10.1117/12.3007764
Distributed fiber acoustic sensing (DAS) technology combined with the existing extensive submarine optical fiber network is an attractive option for real-time underwater seismic monitoring. Here the earthquake monitoring capability of DAS is evaluated, in terms of magnitude estimation, detection coverage, and directional responsivity. The quantitative DAS seismic response is verified by disturbance experiment. The reliability of DAS detection coverage is demonstrated with several seismic events recorded by DAS at Zhaotong test site and the accuracy of DAS magnitude estimation is verified by comparing with seismic station magnitude, which shows great potential for using DAS in global underwater earthquakes continuous monitoring.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353G (2023) https://doi.org/10.1117/12.3007766
The flat-top beam is required in lots of practical applications. However, the semiconductor laser which is widely used as light source has a Gaussian or Gaussian-like energy distribution. In this work, a beam shaping system consisting of aspherical circular lens, Powell lens and cylindrical lens is proposed to transform the semiconductor laser beam into a collimated flat-top beam. The parameters of the Powell lens are designed based on the energy conservation between the incident and output beams, and the cylindrical lens is used for beam collimation. Simulation and experimental analysis are conducted to investigate the energy distribution of the shaped beam at various distances. The results demonstrate a strong agreement between the theoretical expectations and experimental observations, confirming the feasibility and scientific validity of the shaping system. This approach provides an effective method for shaping Gaussian beams into collimated flat-top beams.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353H (2023) https://doi.org/10.1117/12.3007767
Single-Photon detection technology is widely focused because of the higher sensitivity of light detection. Laser in the near-infrared region (1.0-1.7μm) has the advantages of high atmospheric transmittance, weak scattering and weak solar background radiation, which is the ideal working band of aerosol remote sensing and three dimensional imaging Light Detection and Ranging system (LiDAR). Comparing with the other Single-Photon detection technology, the InGaAs Avalanche Photo Diode (APD) detector is widely used in LiDAR system because of its single-photon sensitivity and excellent time-resolved performance. With the development of semiconductor technology, InGaAs single-photo avalanche diode (SPAD) arrays detector integrating multiple pixels and time measurement circuits are widely applied owe to the ability of collecting photon information. This paper concludes the development of InGaAs single-photon avalanche diode arrays and introduces some typical applications of InGaAs single photon avalanche diode arrays in imaging, the prospect of the developing for InGaAs single photon avalanche diode arrays is also discussed.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353I (2023) https://doi.org/10.1117/12.3007771
In recent years, spectral measurement systems based on dual-comb interferometers have attracted more and more attention due to their characteristics of large bandwidth, high resolution, and high frame rate. However, the requirement to maintain strict coherence between light sources greatly hinders the development and application of dual-comb spectroscopy (DCS) systems. In this work, we use the phase-shifted fiber Bragg grating (PS-FBG) and the broadband Fabry-Perot cavity (F-P cavity) to calibrate the relative frequency jitter between two combs instead of introducing other complex feedback control loops. In this way, a DCS system operating at a free-running state was proposed and experimentally demonstrated. With the calibration of the PS-FBG, a 100-MHz resolution over the range of more than 100 nm was achieved without distortion. Benefitting from the excellent wavelength thermal stability, we subsequently corrected wavelength deviation through the optical frequency division process, and the equivalent locking accuracy improved by about 167 times compared with the traditional electrical reference scheme. Finally, the spectral absorption measurement of hydrogen cyanide gas molecules was carried out which was in good consistency with the HITRAN database to verify the potential in molecular spectroscopy. Our scheme is also compatible with other platforms and band ranges and will provide new solutions for free-running DCS systems.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353J (2023) https://doi.org/10.1117/12.3007774
A refractive index (RI) sensor manufactured on a tapered hole-assisted dual-core fiber (HADCF) is proposed. The sensor is manufactured by tapered HADCF between two single-mode optical fibers, and works based on the coupling between the fundamental mode (LP01) and the low-order mode (LP11) in two cores. HADCF is tapered to achieve the phase matching condition between the LP01 mode in the centric core and the LP11 mode in the suspended core. The air hole in HADCF forms microfluidic channels for injecting glycerol solution, and can be free from external interference. The shift of the coupling peak is linear with the RI and sensitivity is 924.57 nm/RIU. In addition, the proposed RI sensor has negligible temperature crosstalk.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353K (2023) https://doi.org/10.1117/12.3007776
In the fringe projection profilometry (FPP), traditionally, no clear mathematical expression was developed to design the sinusoidal fringe patterns for various objects. For this reason, we present an adaptive algorithm to generate the optimum fringe patterns with an oriented bounding box (OBB) and homography transform. Firstly, the features of various objects, which are segmented with deep learning network Mask R-CNN, are represented by the spindle orientation and length of the OBB. Secondly, the adaptive fringe patterns in the field of view of a camera are generated by the fusion with the OBB and the mathematical expression of conventional intensity fringe patterns. Finally, the fringe patterns in the field of view of a camera is transformed into the in the field of view of a projector by homography. Experiments have been carried out to validate the performances of the proposed method.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353L (2023) https://doi.org/10.1117/12.3007781
The fiber Bragg grating (FBG) was written in hollow suspended-core fiber (HSCF) using femtosecond laser point-bypoint technology. The HSCF based-FBG has a higher refractive index (RI) sensitivity to liquid in the air hole because the core of HSCF is completely exposed to air. In the RI range of 1.35~1.45, the reflection peak of the FBG moves toward the longer wavelength with the increase of the external RI. The wavelength shift of FBG is greater for the higher RI, which means that the HSCF-FBG has a higher sensitivity for the high RI environment. The RI sensitivity of the HSCF-FBG is 14.24 nm /RIU in the range of 1.42~1.44. The axial strain sensitivity of the sensor is 1.02 pm /με in the range of 0~900 με, and the temperature sensitivity is 10.22 pm /℃ in the range of 30~150 ℃. The HSCF-FBG RI sensor has higher sensitivity and lower temperature and strain crosstalk, therefore, proposed HSCF-FBG has prospective applications in biological detection, medical and health fields.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353M (2023) https://doi.org/10.1117/12.3007792
Microfabrication of microstructures on the end of an optical fiber is a challenge. A double-interferometer cascaded sensor on the end face of a dual-core fiber is demonstrated to measure the refractive index and temperature. The Michelson interferometer consists of two cores of dual-core fiber, where one core is spliced with a flat-topped microtip, and the Fabry-Perot interferometer is constructed based on an epoxy resin microcap. The fabricated sample achieved a refractive index sensitivity of -14880 nm/RIU and a temperature sensitivity of -374.2 pm/℃. The optical fiber tip microlaboratory has a robust structure and low manufacturing cost.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353N (2023) https://doi.org/10.1117/12.3007796
Absolute phase plays a crucial role in various applications, including camera or projector calibration, stereo matching, structured light measurement, and fringe projection profilometry (FPP). Recently, significant progress has been made in the development of deep learning-based approaches for absolute phase recovery. Many deep neural networks have been created, improved, or directly integrated into the phase retrieval procedure. Analyzing these methods, a common trend is observed in the sequential calculation of wrapped phase, fringe order, and absolute phase. The accuracy of previous results has a direct impact on the subsequent steps, leading to potential error accumulation and reduced recovery speed. To address these challenges, we propose an end-to-end deep learning method based on Res-UNet that directly predicts the absolute phase from a single fringe image without any additional fringe patterns. The presented approach simplifies the procedure of phase unwrapping and overcomes limitations of existing techniques. To note that, to save cost and labor for training the Res-UNet, a novel and virtual digital fringe project system with 3D Studio Max is also established for generating data close to reality. Experiments have been carried out to validate the performances of the proposed method.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353O (2023) https://doi.org/10.1117/12.3007810
The identification of suspended particulate matter has always been an important issue of concern in the field of public health and environmental monitoring. Polarimetry has the advantage of non-invasive, label-free and sensitive to microstructure. The previous work realized the single-particle analysis of atmospheric aerosols based on polarization measurements. While progress has been made in the field of inversion of physical properties of single component aerosols, this paper further focuses on the multi-component mixing problem, and investigate how to apply polarization index system and corresponding data analysis to a wider range of application environments and provide clearer analysis of multi-component aerosol properties. Based on the multi-angle polarization scattering measurement instrument for suspended aerosols, the real-time experimental results of five typical environmental pollutants including motor vehicle exhaust, blind coal, coal, biomass combustion and dust are obtained. The central spectrum and distribution spectrum of 16 polarization indicators at 30°, 60°, 85° and 115° are established firstly. Then, the source identification of the complex component aerosols is solved by nonnegative linear least squares method, and the residual sum of squares is applied to quantitatively describe the accuracy of the source analysis. Compared with the classification method based on the central spectrum of multidimensional polarization index group, the method based on the distribution spectrum presents higher accuracy in source apportionment, which further confirmed the feasibility of realizing a refined aerosol characterization using single particle polarization scattering index and its statistical distribution.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353P (2023) https://doi.org/10.1117/12.3007811
The LED light source is a substantial light source for indoor visible light communication. It has the characteristics of a large divergence angle and a high transmission rate. Therefore, using LED as a light source for visible light full-duplex communication can not only meet the lighting requirements but also transmit information at high speed. To analyze the factors affecting the optical power of the uplink receiving end of the indoor single light source visible light communication, the indoor visible light communication model is established to study the factors affecting the moving range of the reverse end and the optical power of the receiving end. According to the optical path transmission principle of geometric optics, the effects of light source position, link distance, lens aperture, and lens focal length on the moving range of the reverse end and the optical power of the receiving end are simulated and analyzed.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353Q (2023) https://doi.org/10.1117/12.3007812
We have proposed a design of a single side-nickel-core optical fiber (SNCF) and fabricated it using direct thermal drawing for the first time. In our scheme, the metallic-silica heterogenous optical fiber structure was firstly designed and theoretically analyzed by COMSOL, and then thermally drawn from a nickel rod in silica tube preform. The transmission loss of the SNCF at the wavelength of 1550 nm was about 2.28 dB/m. Proven by the microscope observation, the nickel could be well distributed in the side-core of the fiber. It was also proven that the magnetic properties of nickel-core were well preserved after the fiber drawing process. The proposed fiber fabrication method and characterization may be extended to a wide range of other metal-silica heterogenous fibers.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353R (2023) https://doi.org/10.1117/12.3007813
All-inorganic halide perovskite, such as CsPbX3(X=Cl, Br, I) has excellent photoelectric performance, with high fluorescence quantum yield, large carrier mobility, nanocrystalline size adjustment, large gain coefficient and other advantages. It has broad application prospects in light-emitting diodes (LED), solar cells, lasers and other photoelectric devices. However, with the further study of perovskite materials, it is shown that the way and the optimization of the process to enhance the green light efficiency of perovskite is complex, which greatly restricts the development of the device. Local surface plasmon resonance (LSPR) absorption is a unique optical property of nanoparticles and is one of the hot research directions in the field of nanophotonics. It has important applications in enhancing luminous efficiency, Raman scattering, detector absorption and so on. In this paper, the finite-difference time-domain method was used to investigate the variation of the resonance absorption peaks of gold nanoparticles (Au NPs) with sizes. An appropriate size of Au NP was selected to enhance the luminescence intensity of CsPbBr3 thin films. Meanwhile, different dielectric layer materials (SiO2, PMMA, MgF2, respectively) and different thicknesses of them (5, 10, 15, 20 nm, respectively) was chosen to optimize the performance of this structure to prevent fluorescence quenching between Au NPs and perovskite layer. The results show that the size and spacing of Au nanostructures, as well as the refractive index and thickness of the substrate, can significantly affect the LSPR effect. This provides an effective solution and experimental experience for enhancing the efficiency of green perovskite luminescence.
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Tao Meng, Yi Sun, Xinya Liu, Xiaofei Wang, Xiaolei Zhang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353S (2023) https://doi.org/10.1117/12.3007835
Fringe projection 3D measurement technology, as a new type of modern measurement technology, is widely used in various fields, such as reverse engineering, information security, medical diagnosis and other fields due to the advantages of non-contact, high precision, and rapid measurement. The single fringe 3D measurement requires only one deformed fringe image to recover the phase distribution that containing the object information. The paper employs the Fourier transform fringe analysis technique for single-frame fringe phase demodulation. The wrapped phase of the object is recovered through Fourier transformation, frequency domain filtering, and Fourier inverse transformation. Then, the phase unwrapping algorithm is used to unwrap the discontinuous wrapped phase into a continuous phase with practical significance. The traditional phase unwrapping methods that scan line by line and column by column are only suitable for completely sampled wrapped phase fields. The branch-cut method used in this paper is a powerful noise-resistant path optimization phase unwrapping algorithm. This algorithm generates branch-cut lines that represent unreliable areas in the phase unwrapping process and selects paths that avoid these branch-cut lines, thereby constraining the spread of local errors.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353T (2023) https://doi.org/10.1117/12.3007837
Silicon drift detector is widely used as X-ray spectrometer sensor. The advantage of this sensor is the ability to get the precise timing and high resolution spectrum. The dark current of the SDD was suppressed by the thermometric cooler, which cooling the detector to a nominal temperature of -52°C. The electronic circuits were made of two assemblies: the focal plane assembly and the Main Electronics Box. The outputs from the FPA were filtered by the fast and slow shaping amplifiers. Both shaping amplifiers were designed basing on a two stage Sallen-Key filters. The fast shaping amplifier, with 185 ns peaking time, was designed to get a better timing accuracy. The slow shaping amplifier, with 1.68 μs peaking timing, provided better energy resolution, along with the pile-up rejection circuits. A non-delay line constant fraction discriminator was adopted to acquire an accurate arrival time. The photon time-tag error mainly comes from two parts: time triggering and time stamping, which are 65.25 ns and 40 ns respectively. Thus the time jitter was 76.53 ns totally. The photon height was hold by the peak sample holder. The conversion relationship between the voltage and line energy was calibrated. The energy resolution was calculated from the Gaussian fitting. The fit to these values produced electronic noise of 11.38 electrons with 95% confidence level. The soft X-Ray spectrometer, as shown above, was capable of providing precise time resolution in conjunction with excellent energy resolution performance.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353U (2023) https://doi.org/10.1117/12.3007838
We propose a coherent light detection and ranging (LiDAR) with a low probability of intercept (LPI) based on wavelength hopping technology and phase-encoded random modulation technology to achieve long-range detection while reducing exposure risk. A theoretical analysis is constructed for the LPI LiDAR system. The multi-wavelength homodyne detection and distance estimation are achieved by the broadband 90° optical hybrid and the matched filter, respectively. Measurements are conducted under 1064 nm and 1550 nm due to the limitation of available light sources. The experimental results show that when the emission power of the two wavelengths is low, the designed LPI LiDAR can achieve sensorless detection with high distance accuracy at long distances. The used laser warning device cannot alarm the laser emitted by the designed LiDAR with continuous wave regime. The feasibility of the designed LiDAR system to realize silent detection is verified.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353V (2023) https://doi.org/10.1117/12.3007839
The thermal focal length of the side-pumped module was first measured at different pump currents, revealing a relationship between thermal focal length and pump current. Then, a linear resonant cavity was designed and optimized. A 1064 nm pulsed laser was generated by using LD side-pumped Nd:YAG laser and acousto-optic(AO) Q-switching technology. BBO and LBO crystals were utilized for second-harmonic generation (SHG) and sum-frequency generation (SFG), respectively. At a repetition rate of 8 kHz, the maximum average power of the 355 nm ultraviolet (UV) output reached 2.13 W, with a pulse width of 32.7 ns. The optical-to-optical conversion efficiency from 1064 nm to 355 nm was 24.3%. At last an analysis was conducted on the impact of the 1064nm to 532 nm photon number ratio's impact on SFG, and the optimal power ratio is close to 1:2 for achieving high conversion efficiency of 355 nm laser output.
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Jiaqi Zhao, Tao Pu, Jilin Zheng, Hua Zhou, Yunkun Li, Xiaohu Wang, Han Zhou
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353W (2023) https://doi.org/10.1117/12.3007840
A 100-km fiber transmission with 10 Gbit/s is demonstrated based on Y-00 quantum noise randomized stream cipher (QNRC) utilizing cascaded phase shift keying (PSK). The proposed of the experimental scheme is to break the limitation of high-resolution and high-speed digital-to-analog converter (DAC) in the QNRC systems. In this paper, a 10 Gbit/s encrypted signal generated by employing seven cascaded phase modulators (PM) which are driven by designed electrical voltage signals at the transmitter side. The encrypted signal is successfully decrypted by the same six cascaded PMs and digital coherent detection. The experimental results show that the power penalties between back to back (B2B) and 50 km transmission and between B2B and 100 km transmission are 1.2 dB and 2 dB, respectively. The proposed PSK-QNRC system can realize error-free transmission. Meanwhile, the bit error rate (BER) performance of the proposed scheme is well below the forward error correction (FEC) threshold. However, the DAC sampling rate of the traditional scheme is not enough to recover the complete waveform. This proposed scheme greatly improves the security of the system.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353X (2023) https://doi.org/10.1117/12.3007842
A new optical read-out system based on three groups of L-shape 3-axis interferometer is proposed to measure 6-degrees-of-freedom (6-DoF) of the test mass (TM) in the gravitational wave (GW) detection missions. In this system, the source laser is firstly divided into three parts to detect the displacement of the three perpendicular planes of the TM. To decouple the translations and rotations with respect to the XYZ axis, each part of the laser is further applied as the source of the L-shape 3-axis interferometer for the posture detection of each plane. The results of the numerical simulation showed that the solution accuracy of the translation and rotation are better than ±2×10-2 pm and ±3×10-5 nrad respectively, proving the computational accuracy is sufficient for the project requirements. The works above will provide a theoretical basis of the optical read-out system for the space-based GW detection mission.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353Y (2023) https://doi.org/10.1117/12.3007845
2-μm-wavelength-range spectroscopy and telecommunication applications could greatly benefit from the well-developed and highly scalable silicon photonics technology. However, the performance of silicon photonic components operating in this spectral range is still limited by the relatively large waveguide propagation loss. To address this pressing issue, we present an effective solution by harnessing the capabilities of the silicon nitride waveguide platform with its remarkable broadband transparency. In this work, we have successfully designed and demonstrated low-loss silicon nitride waveguides operating at the 2-μm wavelength, exhibiting an impressively low propagation loss of 1.07±0.04 dB/cm. Additionally, we have achieved the successful realization of high-Q microring resonator, exhibiting a record-high Q-factor of ~4.9×105 at the 2-μm wavelength.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129353Z (2023) https://doi.org/10.1117/12.3007847
Silicon Photomultipliers (SiPM) has become more and more important in many fields. In practical applications, its surface needs to be covered with passivation protective layer and anti-reflection coating. The usual practice is to cover the protective layer on the anti-reflection coating. However, the upper protective layer will change the anti-reflection effect. We studied the effect of SiPM surface coverage protective material on its light response characteristics. The simulation result showed that when the surface of SiPM device has SiO2 anti-reflection coating and silicon resin protective layer, the reflection light can be reduced by 27% and the photocurrent can be increased by 20% in the visible and near-infrared wavelength range. When the wavelength of light is 905 nm and the thickness of silicon resin changes in the range of 100 ~ 300 microns, the surface light reflectivity of the device can be reduced from 33% of bare silicon to 5.8% ~ 8.9%. Finally, the transmission spectrum of the double-layer medium composed of a glass slide with a main component of a SiO2 slice and a silicon resin coating was tested. The experimental results showed that the light transmittance of the double-layer coating system in the visible region increased by about 20% after the addition of silicon resin. The experimental results are basically consistent with the simulation results. This shows that the SiPM surface protective coating layer can effectively reduce the reflected light on the surface of the device and further achieve the effect of anti-reflection.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293540 (2023) https://doi.org/10.1117/12.3007857
An explainable feature selection method based on Shapley additive explanation (SHAP) is proposed for the signal recognition of a phase-sensitive optical time-domain reflectometer system. The SHAP value is used to quantify the contribution of a feature. The original features of the signals to be identified are selected according their contributions. The support vector machine algorithm is employed as the classifier to verify the effectiveness and explanation of the proposed feature selection method in the signal recognition on an open dataset from Beijing Jiaotong University. The average recognition accuracy of six types of signals increases to 89.3% and the corresponding recognition time of each sample reduces to 0.097 s. The feature selection method provides a reliable guidance for feature selection and can improve the speed and accuracy of the signal recognition.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293541 (2023) https://doi.org/10.1117/12.3007859
To obtain a narrow linewidth ultra-stable laser for strontium atomic optical clocks, a laser is usually locked to a low-thermal-noise ultra-stable cavity with crystalline coatings through Pound–Drever–Hall (PDH) frequency locking technique. However, crystalline coatings in ultra-stable cavities have been observed with obvious birefringence properties in recently research. In our work, by comparing the incident light between two orthogonal polarization eigenmodes aligned with the slow and fast axes, we investigate photo-birefringent effects on our 30-cm-long room-temperature ultra-low-expansion (ULE) cavity to figure out the noise contribution of frequency. We measured that the light-power sensitivity in the fast axis has a lower value than the slow axis in different modulation frequencies, owing to its opposite contributions from thermal expansion noise and birefringent noise. Finally, we estimated that the noise contribution of incident light aligned with the fast axis is below the thermal noise floor.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293542 (2023) https://doi.org/10.1117/12.3007870
With the advance of optical communication and silicon photonics, dispersion compensators based on chirped waveguide Bragg gratings (CWBG) have developed rapidly in recent years. Nowadays, the longest CWBG has reached 20.11 cm with the largest group delay and lowest propagation loss. However, its group delay is nonlinear due to linear width variation. Thus, the extra third-order dispersion existed and is hard to use for second-order dispersion compensation. In this work, we propose and experimentally demonstrate, for the first time, an on-chip circulator-free dispersion compensator based on silicon nitride (Si3N4) CWBG with large and linear group delay. The dispersion device comprises spiral multi-mode antisymmetric index-chirped waveguide Bragg gratings and an asymmetric directional coupler on an 800-nm-thick low-loss Si3N4 platform. It utilizes two mode conversions to avoid the optical fiber circulator. The width variation function is modified to achieve the linear variation of the effective refraction index while the period remains unchanged. At last, the CWBG-based dispersion compensator is applied in a time-lens system to realize frequency-totime mapping. This integrated device has great potential for diverse applications such as long-haul transmission links, pulse compression, and pulse shaping.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293543 (2023) https://doi.org/10.1117/12.3007888
Wavelength beam combing of semiconductor lasers on a photonic integrated circuit (PIC) provides a simple, robust architecture to realize on-chip light sources for ultrabroadband wavelength division multiplexing (WDM) and multi-species trace gas spectroscopy. Several conventional device structures can be used to realize on-chip wavelength beam combing, such as multimode interferometers (MMIs), arrayed waveguide gratings (AWGs) and Mach-Zehnder interferometer (MZI) devices. However, the bandwidth of these beam combiners is quite limited, usually less than 100 nm. Besides, the insertion loss of these combiners is relatively high. On-chip wavelength beam combiners with a low insertion loss and a bandwidth of a few hundred of nanometers should be further developed. Here we demonstrate low-loss wavelength beam combing of two lasers with a wavelength spacing more than 1000 nm based on an adiabatic silicon nitride coupler. The transmission loss from the cross input to the bar output is around -1.2dB in the 1990 nm to the 2060 nm wavelength range. The transmission loss from the bar input to the bar output is -0.86dB in the 830 nm to the 870 nm wavelength range.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293544 (2023) https://doi.org/10.1117/12.3007912
The precise capture and control of nanoparticles by using optical tweezers has become a hot research topic in the field of nano-optics. Especially, the pulsed tweezers have been robustly used to manipulate the nanoparticles because of the high peak power, compared with the continuous optical tweezers. It is still not yet clear that the difference of light scattering by the nanoparticle in the pulsed and continuous optical tweezers, as well as different dispersion processes. In this work, we constructed a finite element model of a nanoparticle and calculated the light scattering and dispersion by the particle irradiated by the pulsed (femtosecond and picosecond lasers) and continuous trapping beams with the same average power, respectively. Both pulsed and continuous optical tweezers were defined as the highly focused, Gaussian distributed, radial polarized and spherical electromagnetic field. Nanoparticles were chosen to be golden particles. We discussed the electromagnetic field evolution, the particle size effects on the energy loss, and the near field distribution. The simulation results offer the significant information for choosing the best laser source for efficient manipulations and other related fields.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293545 (2023) https://doi.org/10.1117/12.3007943
Optical tweezers, capable of precise manipulations on micron/nano particles, can be greatly used to study the biophysics of cells and the interaction between biological molecules. The mechanical properties of cells are inherent properties of a cell, which could be measured by using a probe navigated by optical tweezers instead of the expensive atomic force microscopy (AFM). However, it is still a great challenge to precisely measure the cell mechanical properties because of the cell deformation highly depending on the contact mechanics of the probe. In this study, the finite element analysis (FEA) method was firstly employed to simulate the cell deformation with the spherical probe manipulated by optical tweezers. Then, cell mechanical responses to the contact force were discussed to investigate the probe radius effects on mechanical properties of cells. Traditionally, Young’s modulus could be calculated in Hertz model with the cell deformation. It was found that the measured results of Young's modulus varied as the probe radius, although the preset mechanical property in the cell model was kept the same. When the contact force was less than 100 pN, the measured Young's modulus of the cell decreased with the increase of the probe radius, and gradually tended to be constant at the state of the maximum deformation. We proposed an algebra method to optimize the Young’s modulus fit to the preset material parameter. This may provide a precise way of predicting the mechanical properties of biological cell manipulated by contact probes.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293546 (2023) https://doi.org/10.1117/12.3007948
The performance bound of a hybrid radio frequency-underwater wireless optical communication (RF-UWOC) system with inverse Mellin transform is investigated. The RF link obeys the Nakagami-m distribution while the UWOC link undergoes the mixture Exponential-Generalized Gamma(EGG) distribution under heterodyne detection and intensity modulation direct detection. In the first place, the inverse Mellin transform technique is applied to derive closed expressions for the upper bound of the probability density function (PDF). By capitalizing on these statistics, the boundaries of the outage probability, the average bit error rate, and the average channel capacity are acquired. The expressions are verifified by the Monte Carlo simulation. The results indicate that the performance of the system is superior when the relay gain is the second case.
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Yuanpeng Ding, Junjie Qi, Lei Shen, Guangchong Dai, Rui Zhai, Jun Chu, Zhao Yao, Lei Zhang, Jie Luo
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293547 (2023) https://doi.org/10.1117/12.3007952
We fabricate the few-mode erbium-doped fiber (FM-EDF) and successfully design a few-mode erbium-doped fiber amplifier (EDFA). By controlling the Er3+ doping of the ring-core structure, the differential modal gain have effectively mitigated. Eventually, an average gain of 25.63 dB with a low differential modal gain of less than 0.6 dB and an average noise figure of 7.5 dB over the whole C-band were obtained.
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Junjie Qi, Yuanpeng Ding, Jun Chu, Guangchong Dai, Rui Zhai, Lei Shen, Lei Zhang, Li Zhong, Jie Luo
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293548 (2023) https://doi.org/10.1117/12.3007953
We fabricated the multi-core erbium-doped fibers (MC-EDFs) and successfully designed a core-pumped four-core erbium doped-fiber amplifier (EDFA). By optimizing the injected pump powers of four fiber cores, we experimentally demonstrated the amplification characteristics. Eventually, an average gain of 25.08 dB with a low inter core gain difference of less than 0.72 dB and an average noise figure of 5.42 dB over the whole C-band were obtained. Besides, the performance of this four-core EDFA was tested under different signal input powers, and the gain difference between different fiber cores can be as low as 0.33 dB.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293549 (2023) https://doi.org/10.1117/12.3007954
A compact single-photon detection LiDAR optical system for aerosol detection with the bistatic and off-axis structure has been designed. This design overcomes the signal crosstalk associated with the transceiver optical system. The working wavelength of the telescope optical system is 1.55 μm. The transmitting telescope optical system has a clear aperture of 74 mm, an effective focal length of 17.780 mm, an object space NA of 0.09. Besides, its wavefront aberration RMS is 0.0000λ (λ=632.8 nm) which indicates that the light becomes nearly collimated after passing through the transmitting telescope optical system. The receiving telescope optical system has a clear aperture of 100 mm, an effective focal length of 271.106 mm, and an image space NA of 0.1814. Its root mean square radii are close to the diffraction limit, indicating minimal optical system aberrations and excellent imaging performance. Based on the design result, a prototype LiDAR system was constructed, and experiments have verified that the system can detect aerosols at distances of up to 7 km with signal-to-noise ratios of the echo photons greater than 1:1. The system exhibited stable and reliable operation.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354A (2023) https://doi.org/10.1117/12.3007959
In order to remove the black pollution crusts on the marble artifacts, picosecond (ps) laser cleaning of marble samples has been performed experimentally at three different wavelengths (1064 nm, 532 nm, and 355 nm). Ablation threshold and cleaning efficiency of the three wavelength lasers have been characterized by measuring monolayer ablation depth with 3D microscope using the blow-off model. It has been found that laser ablation efficiency at 1064 nm wavelength is the highest among the above three wavelengths, while that of 355 nm wavelength is the lowest. The ablation threshold of 1064 nm, 532 nm, and 355 nm laser pulses are 0.198±0.033 J/cm2, 0.573±0.114 J/cm2 and 0.739±0.249 J/cm2 respectively. The advantages and effectiveness of ps laser cleaning have been demonstrated in removing contaminants on the marble samples at three different wavelengths, especially at 1064 nm.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354B (2023) https://doi.org/10.1117/12.3007988
In this paper, laser cleaning of rust layer on an ancient bronze ware has been performed experimentally using picosecond (ps) and nanosecond (ns) laser pulses. Regarding the surface roughness after laser cleaning, optimal cleaning parameters using ps lasers have been obtained. The comparison on the roughness of the cleaned areas after irradiation of ps and ns laser pulses with the same parameters demonstrates the advantages and effectiveness of ps laser cleaning of bronze ware.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354C (2023) https://doi.org/10.1117/12.3007992
Integral imaging is a promising naked-eye three-dimensional (3D) display technology. However, the intrinsic tradeoff between the wide viewing angle and high resolution refrains its further application. In order to enlarge the viewing angle of integral imaging without sacrificing the resolution, we propose a method that employs two overlapped display panels. An additional display panel has been introduced into the conventional integral imaging. The display area of the additional display panel can be divided into transparent region and information-loaded region. The transparent region is loaded with blank information, allowing light to pass through without modulation. The information-loaded region is opaque, which contains element image array (EIA) and blocks crosstalk, then to establish an additional viewing angle. The combination of these two viewing angles forms an enlarged viewing angle. The experimental results reveal the successful establishment of the additional viewing angle, effectively enlarging the horizontal viewing angle of integral imaging from 8° to 16°. The two-layer display method provides the 3D display system with a higher space-bandwidth product, overcoming the constraints between viewing angle and display resolution.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354D (2023) https://doi.org/10.1117/12.3007993
Due to the simple configuration, qualified passive coherence between pulses, and cost-effective characteristics, single-cavity dual-comb sources attract increasing research interest. Actually, such lasers have been experimentally verified in dual-comb metrology such as dual-comb frequency measurement and spectroscopy. Unlike the single-cavity dual-comb fiber laser multiplexed in other dimensions such as wavelength, direction and mode-locked mechanism, polarization-multiplexed pulses own the unique characteristics of overlapping spectra, intrinsic spectral coherence, and tunable repetition rate difference. They are beneficial for the simplification of additional optical amplification and the satisfaction of versatile requirements of dual-comb metrology. Here, we demonstrated a single-wall carbon nanotube saturable absorber mode-locked Er-doped fiber laser to emit wavelength-switchable polarization-multiplexed dual-comb pulses. The intracavity loss is carefully tuned by an additional optical variable attenuator to define the oscillation windows. In both the 1530- and 1550-nm gain regions, spectral-overlapping, polarization-multiplexed pulses are experimentally obtained with the fine configuration of the intracavity state of polarization. The polarization dynamics and tunable repetition rate difference are experimentally revealed. The repetition rate difference is at the tens-of-hertz level, which is somewhat lower than that of the reported polarization-multiplexed fiber laser with additionally introduced polarization-maintaining fiber. Since there are no additional birefringent media, the polarization mode dispersion for polarization-multiplexed pulses is attributed to the residual birefringence. Moreover, the passive mutual coherence is also highlighted. There results provide a simple yet effective way to design switchable and versatile single-cavity dual-comb pulses.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354E (2023) https://doi.org/10.1117/12.3007995
Multilayer defects cause severe reflectivity deformation and the degradation of through-focus imaging quality in Extreme ultraviolet (EUV) lithography. EUV mask repair techniques have primarily focused on the mask modification method to deal with the imaging contrast loss originating from multilayer defects. A multilayer defect compensation method based on three dimensional absorber correction considering through-focus imaging optimization and imaging contrast loss recovery is proposed in this paper. The proposed method compensates for the degradation of the imaging quality caused by multilayer defects with a certain defocus range by shifting the edge of the mask pattern and controlling the absorber thickness of the edge. The interactions between various absorber thicknesses and multilayer defect compensation are explored. Simulations verify that the through-focus imaging quality of the defective masks with bump defects could be obviously improved by the proposed method.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354F (2023) https://doi.org/10.1117/12.3008003
In this work, we fabricated a few mode S-shape waveguide with a length of 20 cm by photolithography, the S-shape waveguide is designed with the minimum bending radius of 8 mm and the maximum bending radius of 13.7 mm. The waveguide core size is 15 μm × 10 μm, and the core pitch is 250 μm. The transmission loss of the waveguide is 0.22 dB/cm at 1310 nm and 0.64 dB/cm at 1550 nm, received by a multimode fiber. While, when the output is received with a single mode fiber, the corresponding values become 0.27 dB/cm at 1310 nm and 0.71 dB/cm at 1550 nm. The crosstalk of the waveguide is lower than -40 dB at 1310 nm.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354G (2023) https://doi.org/10.1117/12.3008017
We demonstrate the generation of Kerr frequency combs with controllable intracavity soliton states by seeding the single continuous wave (CW) driven two coupled nonlinear microresonators with a pulsed trigger. The stable one-, two-, or three-soliton frequency comb can be realized deterministically simply by adjusting the pulse intensity of the trigger signal. Numerical simulations show that the generation of the mode-locked soliton frequency combs is robust without going through any instability or chaotic states. These results provide a means for the deterministic and controllable generation of optical Kerr frequency combs on integrated chips.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354H (2023) https://doi.org/10.1117/12.3008034
With the development of optoelectronic technology, InGaAs/InP avalanche photodiodes (APDs) are more and more used in fiber-optic communication systems with high bit rates and long-distance transmission because of their advantages of high sensitivity, low noise, and high speed. When etching mesa-type InGaAs/InP APDs, the edges of the mesa sidewalls are susceptible to premature breakdown due to the increased electric field, which affects the device's performance. In this paper, a shallow-etched mesa-type InGaAs/InP APD with a guard ring structure is proposed in order to suppress edge breakdown. By using Silvaco TCAD software for simulation, the results show that the structure proposed in this paper can limit the active region in the center region, effectively suppress the edge electric field, make the electric field distribution more uniform, and suppress the uncertainty of breakdowns, so that the reliability of the device is greatly increased. The final optimized device has a punch-through voltage of 16 V and a breakdown voltage of 41.3 V. The device has a diameter of 80 μm. The dark current is about 2.02 nA, and the gain is 36 when the breakdown voltage is 95%.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354I (2023) https://doi.org/10.1117/12.3008035
Terahertz (THz) waves are electromagnetic waves between microwave and infrared with low energy, water absorption, high penetration, and other important characteristics. The frequency range of THz waves is between 0.1 ~ 10 THz. With the development of THz sources and detectors, the imaging technology in the THz band has also been greatly developed. THz confocal imaging technology is performed by scanning the sample layer-by-layer. In which, the combination of pinhole and point light source can filter out the stray beam from the defocusing plane and improve the axial resolution. The superoscillation is a phenomenon in which the band-limited function can oscillate faster than the highest Fourier component. A super-oscillating lens based on such method can generate a focal spot beyond the diffraction limit at any position through complex interference, which is called terahertz super-oscillating lens (TSOL). In this paper, we present a phase-type Fibonacci TSOL, which can obtain a short focal depth and narrow spot diameter. The Fibonacci lens is a diffractive lens that produces multiple foci along the axial coordinate. Its focal depth and focal spot at around 0.3 THz are investigated by simulation and experiments. A THz confocal system based on Fibonacci TSOL is built, and the confocal imaging of 3D printed samples is studied. The lateral and axial resolution of the system is higher than the traditional THz confocal microscope using a single lens.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354J (2023) https://doi.org/10.1117/12.3008036
The beam quality of the semiconductor laser is influenced by the structure of the laser's own waveguide as well as the beam shaping system. The cylindrical lens is used to compress the laser beam in the fast-axis direction in optically pumped source applications. Significant spectral deterioration occurs during the shaping of the laser beam. The spectrum of the laser split into some small peaks and misaligned with the absorption peaks of the crystal, resulting in a decrease in the overall absorption efficiency. In this paper, the reasons of spectral deterioration are investigated, and the spectral characteristics are optimized by varying the the output facet coating film’s reflectivity of the semiconductor laser chip. An improvement scheme for spectral deterioration of high power semiconductor lasers after beam shaping is proposed. The experiment results shows that the deterioration of the spectrum is significantly eliminated when the coating film’s reflectivity is adjusted from 0.88% to nearly 15%. A 976nm high power semiconductor laser chip with 7.16% reflectivity coating film has the highest slope efficiency. Due to a trade-off between spectral quality and the slope efficiency, it is necessary to choose an appropriate coating film’s reflectivity on the output facet surface to achieve both high output power and good spectra. This has important application prospects in future solid-state laser pump source applications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354K (2023) https://doi.org/10.1117/12.3008043
Subsurface defects of optical components will reduce the coating quality, transmission characteristics, damage threshold and other characteristics of optical components, and seriously affect the service life of optical components. In order to quickly and non-destructively detect subsurface defects of optical components, this paper proposes a method for utilizing Through-Focus Scanning Optical Microscopy (TSOM) to detect subsurface defects of optical components. Based on the traditional scanning method of optical microscopy, a set of two-dimensional optical images is collected by scanning through the various focus positions (from above the focus to below the focus, within the focus and out of focus). These acquired images are stacked and arranged in the Z direction to generate TSOM images, and the target is located by obtaining the maximum grayscale value of the detected feature. This method can detect subsurface defects of optical glass with a size of 2μm and locate the depth of defects. Through experimental testing of package samples, it was found that defects of the same depth exhibit consistent grayscale variations. This characteristic enables the differentiation between defects located on the surface or subsurface of the 30nm thick structure.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354L (2023) https://doi.org/10.1117/12.3008053
Metasurfaces have been integrated on optical fiber with the advancing stage of nanofabrication technologies, and the combination of them has expanded the application prospect of "Lab-on-fiber". It is worth noting that most optical fiber integrated metasurfaces devices adopt the method of integrating the metasurfaces at the optical fiber end, the dimension of optical manipulation in the free space is limited above the optical fiber end. In this paper, we proposed an optical waveform conversion device based on micro-nano optical fiber integrated catenary wave-driven metasurfaces. Around the surface of micro-nano optical fiber, wave-driven metasurfaces composed of a series of catenary-shaped rings are introduced to realize beam focusing from guided mode of optical fiber to the out-plane mode in the free space. We demonstrated that the input light with wavelength of 980 nm was injected into the micro-nano optical fiber to form the fundamental mode (FM) guided in the core, then the FM was radiated to the free space form beam focusing by the catenary-shaped rings. Especially, the outline of catenary is equivalent to a convex lens, the beam focusing can be enhanced. In addition, adjusting the horizontal span, height of catenary, the intensity, position and shape of focus points can be controlled. Moreover, we changed the angle between the catenary-shaped rings and the polarization direction of the FM, the focus points can be symmetric and asymmetric rotated. The device has potential applications in the fields of optical communication, optical manipulation, and optical imaging.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354M (2023) https://doi.org/10.1117/12.3008058
With the growing interest in less-mode fibers in telecommunication and high-power lasers, fiber mode diagnostic techniques are gradually becoming one of the research hotspots in the field of lasers. In this paper, a four-channel off-axis holography is introduced to represent the polarization and the mode coefficients of LP modes in few-mode fiber simultaneously. A simulation study of Hi1060 fiber containing six linearly polarized modes at 632.8nm is carried out, and the results show that the errors of each mode coefficients is lower than 0.05, and the similarity of intensity before and after mode diagnostic is above 0.97.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354N (2023) https://doi.org/10.1117/12.3008061
Here, we present an innovative integrated near-infrared Kerr comb sensor chip designed for the simultaneous detection of multi-gas. This sensor is comprised of a microcavity featuring a feedback arm for backward coupling and a compact air-slotted sensing element. The microcavity used to form the optical comb has a symmetric dual-spiral structure with an ultra-high resolution of the absorbance spectrum and a roundtrip length of roughly 1.46 μm, which corresponds to a low repetition frequency of about 9.82 GHz. Through the application of horizontal single-slotted structured silicon nitride (Si3N4) waveguides, optimized dispersion engineering of the microcavity can be achieved, resulting in spectra with an octave-spanning bandwidth. The sensing element employs a large-length waveguide, instead of a conventional discrete gas absorption cell, which brings high compactness. By optimizing the degree of thermally tuned interference and pumping parameters of the microcavity structure, a coupling-free light source in the form of a multi-soliton comb with a pump-comb conversion efficiency of over 50% can be achieved. The sensor performance is accurately evaluated through theoretical simulations of noise-containing absorption spectra of multiple gases, confirming its applicability.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354O (2023) https://doi.org/10.1117/12.3008069
Laser triangulation ranging sensors, with their micron precision, simple principles and compact structures, are widely applied in the industry for instance for workpiece shape and defect measurements. However, the determination of system parameters for laser triangulation sensors currently depends on the experience and manual attempts of designers, which is not only time-consuming but also enables additional measurement errors. In this work, we present a genetic algorithm based method to accurately, fast, and adaptively determine the optimal system parameters for various measurement requirements. Based on the Scheimpflug principle, measurement range and resolution expressions are first derived for laser triangulation systems. The formulas of laser spot size in the x- and y-directions of image detectors are presented and the system geometric dimension is constrained when setting the measured surface on the calibration reference plane. Furthermore, a nonlinear programming genetic algorithm (NP-GA) is proposed to evaluate system parameters for certain measurement conditions, in which the local search capability is significantly improved with rapid convergence to the optimal solution. The algorithm allows determining the parameters by setting diverse measurement resolutions with a relative uncertainty below 3.7% in 3 s. ZEMAX simulations of the sensor systems are performed with non-sequential mode to validate NP-GA determined system parameters. Simulation and computed results show the relative differences of the parameters dependent RMS radius of the laser spot on the image detector are below 0.35% and 8.72% in the x- and y-directions, respectively.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354P (2023) https://doi.org/10.1117/12.3008077
At present, most ultra-stable lasers are locked onto the optical cavity through Pound-Drever-Hall (PDH) technology, but the frequency instability of the locked laser is often limited by the thermal noise limit of the reference cavity. It can mainly be reduced by increasing the cavity length, or operating at cryogenic temperatures. Here, we present an ultra-stable laser based on a 30-cm-long room temperature cavity. The cavity consists of an ultralow expansion (ULE) glass spacer and fused silica (FS) mirrors with Al0.92Ga0.08As/GaAs crystalline coatings. A 1396.9-nm laser is stabilized on this cavity and a periodically poled lithium niobate (PPLN) waveguide is used to obtain 698.45 nm light for the strontium atomic clock by second harmonic generation (SHG). Technical noise contributions are estimated by beating another 698nm ultra-stable laser system based on a commercial 30-cm-long cavity. The zero-coefficient thermal expansion (zero-CTE) temperature of the cavity is about 266.2 K, and the time transport constant is 1.2×106 s. The total noise is the sum of all estimated noise contributions and the short-term frequency stability mainly dominated by the vibration noise. The evaluation of total noise is close to the frequency instability of the 1×10−16 at the 1 s average time.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354Q (2023) https://doi.org/10.1117/12.3008086
A power stabilized butterfly-packaged diode laser (BPDL), which will be used as the calibration light source for the coronagraph module in the China Survey Space Telescope (CSST), was developed. An iris diaphragms (ID) was used to block the backscattering light from the end-face of coupling optical fiber. Additionally, the polarization direction of laser beam was adjusted to precisely coincide with the fast axis of the coupling optical fiber. The power of the BPDL was measured for four hours, resulting to the root mean square (RMS) value is smaller than 0.1% and the peak-to-valley (PV) value is smaller than 0.5%. Performances of the BPDL are presented. The developed BPDL can pass the aerospace environmental tests, indicating that the BPDL can be suitable for space missions.
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Dechun Dan, Jiefeng Luo, Yong Yang, Zijie Wang, Yang Yu, Yang Wang, Qi Zhang, Xiaobei Zhang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354R (2023) https://doi.org/10.1117/12.3008087
A novel parallel Fabry-Perot interferometer (FPI) assisted by a concave cavity structure and an external reflector, which can be employed for large-range displacement and temperature sensing, is proposed and experimentally demonstrated. Therein, the concave cavity consists of a single mode fiber (SMF), a graded index fiber (GIF) and a hollow core fiber (HCF), which are fusion spliced to realize flat and concave surfaces of SMF-GIF and GIF-HCF, respectively. The certain length of GIF is utilized to serve as an collimator, facilitating the reduction of the divergence angle and the expansion of the mode field radius of the propagating beam. Thus the propagating beam can split into the concave cavity structure’s sidewall and inner air area, when the concave cavity size is smaller than the mode field diameter of the beam from GIF. The external Fabry- Perot interferometer (EFPI), formed by GIF endface and the external reflector, is utilized to detect displacement. Meanwhile, the intrinsic Fabry-Perot interferometer (IFPI), formed by the endfaces of GIF and HCF, serves as a temperature sensor. The length of the silica cavity changes with temperature due to the thermal expansion and thermo-optical effect of silica. In consequence, the corresponding wavelength shift can be accurately observed in response to temperature variations. The experimental results indicate the displacement sensing range of EFPI is up to 30 mm, which is greatly increased compared to other FPI displacement sensors. Moreover, the proposed sensor has a temperature sensitivity of 11.52 pm/◦C in the range of 30◦C 100 ◦C.
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Huachen Li, Xin Wang, Lu Wang, Lulu Yang, Meng Zhang
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354S (2023) https://doi.org/10.1117/12.3008100
Depth information is crucial for 3D scene reconstruction. Combining the advantages of active illumination, a 3D imaging method using engineered active illumination and double-helix point spread function (DH-PSF) is proposed. It projects a dense pattern of dots onto the object's surface, and a commercial camera captures the dot pattern through a pair of micro lens arrays in a 4f configuration, which includes a DH phase array at the 2f position on the Fourier transform plane. DH-PSF encodes depth information of the object, and by measuring the rotation angles of the two lobes of the dots on the object's surface, the distance between the imaging systems can be obtained. Simultaneously, the twodimensional image of the object can be reconstructed based on the captured images and the known DH-PSF. The proposed 3D imaging method can reconstruct the 3D structure of the object from a single captured 2D image. It has the advantages of improving distance resolution and reducing system complexity.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354T (2023) https://doi.org/10.1117/12.3008102
The polarization control of silicon photonic integrated devices is an urgent problem caused by the birefringence effect due to the structural asymmetry of the silicon (Si) waveguide (450 nm × 220 nm), which results in polarization loss, polarization mode dispersion, and wavelength polarization related issues. This work presents a proposal for a compact silicon hybrid plasmonic waveguide (HPW) polarization controller. The proposed design includes two sets of Bragg gratings, placed within different material layers of the polarization controller. By changing the relative positions of the two sets of Bragg gratings, the absorption problem generated by the hybridized modes can be reduced or even eliminated, thus the reflection spectrums of the TE and TM polarization mode are optimized. Besides, one polarization mode of TE mode and TM mode has a high reflectivity, while the other polarization mode has a high transmission by designing different grating periods and other parameters. Based on the simulations and design, the silicon HPW polarization controller has an optimal length of 23.247 microns when used as a TM-mode polarization reflector, and the corresponding optimal length is 19.694 microns when used as a TE-mode polarization reflector. At the working wavelength, the polarization extinction ratio (ER) and insertion loss (IL) of the TM-mode polarization reflector are greater than 28.1 dB and less than 0.087 dB, respectively, and the ER and IL of the TE-mode polarization reflector are greater than 18.9 dB and less than 0.085 dB, respectively. Compared with conventional silicon waveguide polarization controllers, TE mode and TM mode separation, selection, transmission, and reflection of the proposed silicon HPW polarization controller can be achieved with a compact size. In the future, will be potential for widespread applications for this technology in both silicon photonic devices and silicon photonic integrated circuits.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354U (2023) https://doi.org/10.1117/12.3008114
We demonstrate a method for extracting the spectral parameters of the distributed feedback (DFB) laser based on an adaptive differential evolution algorithm. By using the multi-objective optimization method to fit the measured spectrum, the relevant-parameters of the spectrum can be rapidly and accurately extracted. Experimental results show that the proposed method can obtain high accuracy of DFB laser spectrum parameters extraction. Moreover, this method is suitable for a wide range of applications, including spectrum fitting and other parameters extraction.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354V (2023) https://doi.org/10.1117/12.3008125
A type of high-polarization-isolation optical parametric amplifier (OPA) is reported based on the difference-frequency generation (DFG) process and the sum-frequency generation (SFG) process in a periodically polarized lithium niobate (PPLN) waveguide. Two OPA schemes using x-cut and z-cut PPLN waveguides are proposed and numerically demonstrated. The simulation results show that, the output polarization isolation up to 39.77 dB and 35.68 dB can be obtained with x-cut and z-cut PPLN waveguides, respectively.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354W (2023) https://doi.org/10.1117/12.3008126
With the application of various advanced technologies, the record of transmission reach in optical fiber communication has been continuously improved. In long-haul systems, in order to provide a higher power budget, the transmit power is increased, resulting in more severe nonlinear effects. However, the digital back propagation (DBP) algorithm, as a commonly used nonlinear impairment compensation method, requires accurate channel parameters when performing compensation, which is impossible in practical applications. To solve this problem, an adaptive DBP (ADBP) method based on data reduction is proposed in this paper, which is called data reduction ADBP (DR-ADBP). In DR-ADBP, instead of using all the received samples, a block with a certain length of them is selected and then applied to the adaptive algorithm to reduce the overall complexity. After the accurate parameters are searched by the adaptive algorithm, the DBP operation for all samples is performed then to compensate for the impairment. The proposal of the adaptive algorithm is under the guidance of the analysis of the nonlinear impairment and the adaptive cost function, which is more in line with the characteristics of the optical fiber channel. The proposed method is verified in a coherent optical communication system. The results show that under different initialization nonlinear scale factors, the convergence of nonlinear coefficients can be achieved by DR-ADBP with fewer iterations, and the required running time is much lower than that of the previous ADBP.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354X (2023) https://doi.org/10.1117/12.3008137
In situ strain sensing at high-temperature environment is crucial in the aerospace field. Silica fibers will soften at 700 ℃, which can hardly be utilized for strain sensing at higher temperatures. Notably, single crystal sapphire fiber is a promising material for high-temperature sensing due to the high melting point (~2045 ℃). Here, we report the strain sensing at 800 ℃ of sapphire fiber Bragg gratings (SFBG) inscribed by a femtosecond laser lineby- line scanning technique. At first, a line-by-line sapphire fiber grating was inscribed using femtosecond laser direct writing technique. The sapphire fiber ends were polished into bevels to reduce Fresnel reflections, and the signal-to-noise ratio of the SFBG was improved from 9 dB to 17.2 dB. And then, strain characteristics of the SFBG were investigated at room temperature. It was found that the maximum strain of SFBG was decreased to 3600 με (64% reduction) comparing with 9714 με of the pristine sapphire fiber, which is due to the micro-damage introduced by femtosecond laser pulses. In addition, the strain sensitivity of the SFBG is 1.42 pm/με. Subsequently, a strain sensing experiment of the SFBG was carried out at 1100 ℃ using a high-temperature tensile testing system. After annealing at 1100 ℃ for 4 h to improve the high-temperature stability, the SFBG exhibited a strain sensitivity of 1.6 pm/με (R2=0.998) at 1100 ℃. As a result, strain sensing at 1100 ℃ environment was realized based on the SFBG, which indicates a promising application in the aerospace field, especially in strain sensing for structural safety monitoring of hypersonic aircraft at high-temperature.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354Y (2023) https://doi.org/10.1117/12.3008141
Chirped and tilted fiber Bragg grating (CTFBG) was fabricated in SMF-28e fiber by using femtosecond laser line-by-line technology. The tilt angle and chirp rate of above-mentioned CTFBG were 8° and 10 nm/cm, the insertion loss, 3dB-bandwidth, filtering efficiency and central wavelength were 0.8 dB, 75 nm, 75% and 1511.38 nm, respectively. In addition, chirped FBG (CFBG) and tilted FBG (TFBG) were fabricated by using femtosecond laser line-by-line technology, and the spectral properties of CFBG, TFBG and CTFBG were compared and analyzed.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129354Z (2023) https://doi.org/10.1117/12.3008146
Vibration monitoring is crucial in many fields such as seismic detection, oil and gas exploration and structural health monitoring. Here, we present a novel directional accelerometer using a highly localized fiber Bragg grating (FBG) fabricated by a beam-shaping femtosecond (fs) laser point-by-point (PbP) technology. The FBG was inscribed with asymmetric refractive index modulations (RIMs) in the fiber core of a single-mode fiber (SMF), ensuring directional coupling of cladding mode resonances and thus providing a sensing mechanism for directional vibration response. A reflective accelerometer was achieved by sputtering a nano-gold reflector on the fiber end of the FBG. The acceleration sensitivity and directional dependence of the accelerometer were experimentally investigated, which exhibited an excellent directional vibration response with a maximum acceleration sensitivity of 0.113 V/g at high temperature of 450 ℃. Notably, the core mode resonance of the FBG can be used to calibrate the power fluctuations and cancel out the temperature crosstalk. The proposed directional accelerometer is compact, flexible, and high-temperature-resistant, which exhibits promising potential for structures vibration monitoring in harsh environments.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293550 (2023) https://doi.org/10.1117/12.3008152
The spatial resolution of conventional Brillouin optical time domain reflectometry (BOTDR) is intrinsically limited by the relaxation time of phonons in the fiber. To make use of the narrow pulse width for higher spatial resolution, the double-pulse probe can induce interference between two acoustic waves, making it possible to determine the Brillouin frequency shift from the oscillating Brillouin gain spectrum. However, the signal-to-noise ratio (SNR) is restricted since the pulse width is quite narrow. In this paper, we propose to combine the double-pulse technique with coding pulse to improve the SNR while maintaining high spatial resolution. The complementary return-to-zero (RZ) Golay codes are employed in the experiment, and every code element is expanded to contain the entire form of double-pulse. Thus, the interference pattern from the double-pulse interaction is guaranteed, and the decoding process can be correctly conducted. Experimental results demonstrate a significant SNR enhancement with a submeter-level spatial resolution.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293551 (2023) https://doi.org/10.1117/12.3008178
Couplers have always been crucial in integrated optics, particularly in silicon-based integrated optics, where silicon-based couplers are used to couple silicon-on-insulator (SOI) waveguides and common single-mode optical fibers. However, direct coupling between single-mode fibers and silicon waveguides causes significant coupling losses due to the huge difference in mode spot size. In this research work, we propose a novel cantilever-based silicon-on-insulator edge coupler. A silicon waveguide with a cantilever structure is first created on an SOI wafer, and then silicon dioxide (SiO2) and silicon nitride (Si3N4) layers are alternatively placed on top of it and etched into ridge waveguide shapes. At the same time, the dimensions of the silicon waveguide in the longitudinal direction (light transmission direction) taper to form a tapered waveguide, and the refractive index of the Si3N4 tapers in the longitudinal direction as the longitudinal length of the Si3N4 shortens layer by layer from bottom to top. The coupling efficiency of a single-mode fiber with a mode field diameter of 10.4 μm and the SOI silicon waveguide exceeded 91%. The silicon coupler was simulated and constructed using the finitedifference method in time domain (FDTD) and the eigenmode expansion (EME) method. This highly effective SOI silicon coupler is crucial for silicon optical integration and may be used in a variety of situations, including optical computing, optical sensing, and optical communication.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293552 (2023) https://doi.org/10.1117/12.3008180
In this paper, an intensity modulation direct detection interconnection system employing modeling-driven neural network (MDNN) assisted low-density parity-check code (LDPC) is proposed and experimentally demonstrated. The weights and biases are utilized to optimize the decoder parameters through model-driven deep learning LDPC decoding processing. Compared with traditional schemes that employ LDPC decoding with high computational complexity and redundancy, the proposed scheme has the advantages of a relatively lower complexity decoder and higher decoding gains. The results show that the MDNN signals can provide a 0.28-dB improvement in receiver power sensitivity and a 46% reduction in complexity in a 10-km IMDD optical four-pulse amplitude modulation interconnection system.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293553 (2023) https://doi.org/10.1117/12.3008229
In order to investigate the relationship between the interface parameters of an optical interface/system and its polarization characteristics, a three-dimensional (3D) polarization ray-tracing Mueller algorithm is proposed in this paper. Firstly, using the optical design simulation software CODE V or ZEMAX, the vector modeling of the optical system and the pupil sampling or field of view sampling of the incident light are carried out. Secondly, according to the surface type of each optical interface in the optical system and whether the optical coating is plated, the 3D polarization ray-tracing of each optical interface is carried out, and the 3D Mueller matrix Ml (9×9 order) of each optical interface under the respective local coordinate system is calculated. Then, a 3×3 order rotation transformation matrix R is introduced by using the rotation transformation of the global coordinate system, and the 3D Mueller matrix Mg (9×9 order) of each optical interface under the global coordinate system is obtained. Based on the 3D polarization algorithm proposed in our published paper, the 3D Mueller matrix M of each sampled ray through whole optical system is calculated. Finally, if the polarization state of the incident light of the optical system is known, the polarization state of the emitted light can be accurately calculated. Especially, the 3D polarization ray-tracing Mueller algorithm is not only suitable for handle the totally, partial and unpolarized light through the optical system, but also suitable for quantitative calculation of the polarization properties of an arbitrary surface, including spherical/aspherical/free-form surface.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293554 (2023) https://doi.org/10.1117/12.3008233
This paper proposes a distributed optical fiber sensing system based on a semiconductor laser with optical injection. Due to the reflection of the mirror at the end of sensing fiber, an external disturbance causes the simultaneous changes in phase of the light bidirectionally propagating in the fiber. The phase modulation induced by the external disturbance is converted into intensity modulation by the nonlinear effect of optical injection. Two waveform-changes induced by the same disturbance appear at the output signal. There is a time difference between the two changes, which is equal to the round trip time of the light from the disturbance position to the mirror. The disturbance location can be realized according to the time difference. The location performance of the system is studied through experiments, and the location errors at different positions on the 4.0859 km sensing fiber are less than 15 m. The experimental results indicate that the system is timely in detection on external disturbances and simple in location method.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293555 (2023) https://doi.org/10.1117/12.3008245
In this paper, an intensity modulation and direct detection (IM-DD) discrete multi-tone (DMT) interconnection system employing polar coded and deep learning-assisted forward error correction decoding probabilistic shaping 16 quadrature amplitude modulation (PS-16QAM) is studied. By employing many-to-one (MTO) based PS to achieve signal Gaussian distribution model, the proposed optical DMT system is with the advantages of shaping overhead free profile, and optimized polar coded modulation architecture. To overcome the ambiguous problem for the overlapping symbol decision in PS, a deep learning assisted forward error correction decoding is proposed for belief propagation (BP) based polar decoding. The computational complexity of deep learning assisted polar decoding is superior to the original BP decoding one, and with faster rate convergence and better optical transmission performance. Simulation results in a 100Gb/s optical DMT transmission system present that, the deep learning assisted polar coded PS-16QAM signal achieves 0.38-dB superior receiver power sensitivity compared with conventional polar coded system over 10-km standard single mode fiber transmission.
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Zhijie Ma, Jun Zhang, Mengyuan Xie, Xiaolian Lu, Meizhong Liao
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293556 (2023) https://doi.org/10.1117/12.3008251
Traditional continuous zoom microscopes are limited to two-dimensional observation, whereas the 2D/3D continuous zoom microscope not only enables continuous zooming in a two-dimensional plane but also allows for switching to three-dimensional observation mode, providing additional information about the side view of the specimen. This paper presents the design of a 2D/3D continuous zoom objective lens based on zoom system theory. Using negative group zoom and negative group compensation method, the system was designed using Zemax software. It consists of four groups: front fixed group, zoom group, compensation group, and rear fixed group, forming a mechanical compensation-based continuous zoom objective lens optical system. A catadioptric structure was incorporated to enable three-dimensional stereoscopic observation. This paper introduces initially a four-element continuous zoom objective lens with magnification ranging from 0.7× to 4.5× and a numerical aperture between 0.025 to 0.09. This lens possesses a working distance of 90mm and a conjugate distance of 324mm. Subsequently, building upon this continuous zoom objective lens, a three-dimensional observer was introduced, transforming it into a switchable 2D/3D continuous zoom objective lens. The working distance is 70mm, and the magnification varies from 0.4× to 2.5×. Design results demonstrate that, whether in the 2D or 3D mode, this system can be aligned with a 1/2-inch sensor. Across different observation modes, the MTF curves for various magnification closely approach the diffraction limit, and the spot diagram remain smaller than the Airy disk, showing good imaging quality, expanding the application scenarios of continuous zoom objective lens.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293557 (2023) https://doi.org/10.1117/12.3008281
In X-ray critical dimension metrology (XCD), it is a common practice to select an appropriate measurement configuration, including incidence angle, azimuth angle, exposure time, etc., to improve measurement results. This is crucial as the quality of the obtained signature is impacted not just by the instrument's precision, but also by the specific chosen measurement configuration. This is known as the measurement configuration optimization (MCO) problem. This paper proposes a general MCO method based on the theory of error propagation and error estimation techniques using condition numbers. Finally, the MCO problem in XCD is framed as optimizing the "max-min" condition number of the coefficient matrix within the context of linear error estimation. The proposed method is showcased on "virtual experiments" conducted via simulations to determine the optimal combinations of rotation angles along two coordinate axes. The method's feasibility is substantiated through a comparison with the distributions of parameter uncertainty. The results suggest that the proposed method holds promise as an alternative approach for comprehensive evaluation in the context of the MCO problem in XCD and various measurement scenarios.
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Yifan Shen, Jianyong Zhang, Xiaodie Qing, Chunyue Zhou, Shuchao Mi
Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293558 (2023) https://doi.org/10.1117/12.3008407
Research to mode division multiplexing (MDM) systems based on few-mode or multi-mode fibers is one of the hot spots to achieve the demand for rapidly increased global user data traffic. Polar code, with a very low encoding and decoding complexity to achieve Shannon Limit, is worthwhile to apply to MDM systems into the research. Besides, the acquisition of channel state information (CSI) is of great significance for equalization and detection of coherent receivers. However, CSI is considered to be fully known at receiver in most existing research and few research discusses impact of imperfect CSI induced by channel estimation on MDM systems.This paper investigates channel estimation problem in a polar-code-encoded fiber-optic MDM (P-PC-MDM) system, and studies effect on system performance with channel estimation under impact of mode-dependent loss (MDL) using different Multiple Input Multiple Output (MIMO) detection algorithms: Maximum Likelihood (ML), Minimum Mean Square Error (MMSE) and the improved Alternating Direction Method of multipliers based Infinity-Norm (ADMIN). Simulation results demonstrate that P-PC-MDM system achieves a low bit error rate in the range of 2-3 dB SNR faster than MDM system of more than 10 dB. Besides, the addition of channel estimation error acceptably degrades system performance, and the improved ADMIN detection algorithm has a better bit error rate performance than MMSE by 0.5-2dB, and computational complexity is 13 times lower than ML.Therefore, the P-PC-MDM system is proved to be feasible, and the improved ADMIN detection algorithm can represent a good candidate in P-PC-MDM system with channel estimation and MDL.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 1293559 (2023) https://doi.org/10.1117/12.3008409
In deep ultra violet (DUV) lithography, the thermal deformation of the reticle reduces the quality of the reticle pattern transferred to the silicon wafer, and also causes errors in the image quality measurement of the projection objective. Therefore, it is necessary to establish a physical model to study the thermal deformation rule of reticle, so as to provide theoretical support for the development of reticle thermal deformation correction method. This paper employs finite element method (FEM) simulations to investigate DUV lithographic reticle thermal deformation. Results show that under 263.7 W/m² irradiation, reticle temperature and deformation increase, reaching dynamic equilibrium. Maximum equilibrium temperature is 302 K; reticle deformation equilibrium values (Δxr, Δyr) at maximum field of view (FOV) are (21 nm, −18 nm). This work highlights the intricate interaction between thermal forces and reticle deformation, emphasizing the need to manage these effects for lithography. Such insights are crucial for advancing semiconductor fabrication processes.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129355A (2023) https://doi.org/10.1117/12.3008432
Recently, the frequency-shifting (FS) projection technique provides a promising alternative to the traditional phase-shifting (PS) fringe projection profilometry (FPP). It solves the absolute phase retrieval problem directly in a completely different fashion, without any phase unwrapping. However, due to the Nyquist sampling theorem (NST), a constant frequency-shift only supports for a limited effective field (EF). It only covers a limited region of the fringe pattern, and the phase retrieval quality degenerates dramatically for those out of the EF. This issue tends significant especially for a high-resolution fringe pattern, limiting the practical application in real life. To this end, we introduce the non-uniform sampling strategy into frequency-shifting technique. With a temporally varying frequency-shift, the EF can be improved significantly, achieving globally high quality across all regions in the pattern for the retrieved phase. Simulation and real experimental results have validated the efficacy of the proposed technique.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129355B (2023) https://doi.org/10.1117/12.3008436
We designed and fabricated a silicon nitride (Si3N4) micro ring resonator filter coupled with a straight waveguide grating coupler in the visible wavelength range. The key parameters of the micro ring resonators, including the waveguide crosssection size, bending radius, coupling spacing as well as the linewidth and period of the grating coupler, are optimized to obtain an resonant output in the range of 730~780nm. Then, Si3N4 micro-ring resonators with different parameters are patterned by electron beam lithography (EBL), inductively coupled plasma etching (ICP) and other processes. At last, the filtered light peaks and the free spectral range of the micro ring resonator are characterized, which are found to be tunable by varying the cross section of the waveguide and the radius of the ring. In addition, by replacing SiO2 with Polyvinyl alcohol (PVA) resin as the upper cladding of the device, the flatness of the top surface of the device can be further improved with a simplified process. Our study lays a foundation for the heterogeneous integration of different materials with COMS compatible silicon nitride platform.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129355C (2023) https://doi.org/10.1117/12.3008446
Halide perovskite (ABX3) has become an exciting material for research in next-generation optoelectronic devices because of their remarkable photoelectric properties of high stability, high luminescent quantum yield and high carrier mobility. However, the presence of different halogen elements in perovskite could have a significant impact on their optical physical properties. That’s because they have a huge differences in the environmental exchange and migration characteristics. In this work, the samples with three different anions of CsPbBr3, CsPbCl3, and CsPb(Br0.5Cl0.5)3 were used, and the electrical stability and photostability experiments were carried out under the dark environment and under continuous illumination with a 532 nm wavelength light, respectively. The electrical, optical and thermal stability of the photodetectors were analyzed by adding a constant voltage of 10 V to the photodetectors and repeating the experiments for 10 times in the dark and under continuous illumination, and the trends of the I-V curves of the photodetectors were recorded. The experimental results show that the anionic halides have considerable defects leading to their poor electrical, optical and thermal stability under dark and continuous light conditions. However, the all-inorganic mixed halide perovskite CsPb(Br0.5Cl0.5)3 is able to form tightly bound surface ligands effectively suppressing the defects generated on the surface, which results in its better stability and linearity. Therefore, it indicates that the photodetectors based on allinorganic mixed halide perovskite have excellent stability, which provides a promising way to promote the research of all-inorganic halide perovskite devices in the future.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129355D (2023) https://doi.org/10.1117/12.3008449
All inorganic perovskite ABX3(X=Cl, Br, I) is widely used in the research of laser devices due to its excellent optical properties, such as high luminescence quantum yield, large gain coefficient, high carrier mobility and adjustable wavelength, etc. Compared with traditional edge-emitting lasers, vertical cavity surface emitting laser (VCSEL) has great advantages in beam quality, fiber coupling efficiency, single longitudinal mode and cavity surface reflectivity. In this experiment, all-inorganic perovskite material is used as the optical gain material, and an optical pump composed of distributed Bragg mirror (DBR) is used to construct a vertical cavity surface-emitting laser. The DBR mirror parameters (SiO2/TiO2 and SiO2/Ta2O5, respectively) and DBR layers (5, 8, 10 and 12, respectively) were simulated by Finite Difference Time Domain (FDTD) method. The results show that the reflectivity of DBR composed of SiO2/TiO2 material in 10/12 layer is closer to 99.95%, and the DBR mirror can realize the photon limitation to a greater extent and form resonance. On this basis, the vertical cavity of different cavity lengths (λ/2 and 3λ/2, respectively) were simulated. It was found that choosing a proper cavity length is able to achieve a single mode lasing of green emission in 532 nm, and its resonator quality factor (Q factor) will more than 8000. Therefore, from the results of electric field intensity of different samples, it was found that a shorter cavity gives rise to a stronger restriction on light field and photon, and a more concentrated on mode distribution. And thus, a higher Q factor will be demonstrating that is more conducive to the performance of laser device. This work also provides the theoretical analysis model and related parameters for the preparation of lasers.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129355E (2023) https://doi.org/10.1117/12.3009607
Thin film lithium niobate (LN) is considered a promising platform for integrated photonics owing to its exceptional electro-, nonlinear-, and acousto-optic properties. In this work, we propose the generation of broadband optical frequency combs in an LN microring resonator by dispersion engineering. We design the structure of the LN waveguide to adjust the effective refractive index of its fundamental mode so that the microring resonator can generate two dispersive waves near the pump light to achieve a broadband optical frequency comb up to 4/5-octave range (about 110 THz). The broadband frequency comb is crucial for future on-chip LN nonlinear photonics applications.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129355F (2023) https://doi.org/10.1117/12.3010040
In fast-than-Nyquist wavelength division multiplexing (FTN-WDM) systems, the severe shaping filtering introduces serious inter-symbol-interference, and the long-distance fiber optical transmission also leads to more complex link impairments. Traditional chromatic dispersion (CD) estimation algorithms face the problems of difficulty in balancing complexity and estimation accuracy, and sensitivity to polarization mode dispersion (PMD) impairments. Aiming at the problem of large CD estimation error when traditional CD estimation algorithm has large PMD damage, a PMD-tolerant CD estimation algorithm for FTN coherent optical transmission systems is proposed. The algorithm achieves coarse CD estimation by stacking training sequences insensitive to PMD damage, and completes finer CD estimation by using the consistency parameter of clock phase detection. 64GBaud PM-16QAM FTN-WDM simulation results show that when the acceleration factor is 0.85 accumulated CD is 15360ps/nm and the CD estimation error is 200ps/nm, the PMD tolerance is about 100ps, and the complexity and PMD tolerance are 0.24 and 2.5 times of the peak average power ratio (PAPR) blind CD estimation algorithm, respectively.
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Proceedings Volume Fourteenth International Conference on Information Optics and Photonics (CIOP 2023), 129355G (2023) https://doi.org/10.1117/12.3011196
In this paper, we study the optimal alignment and anti-alignment of O2 molecules induced by the femtosecond laser pulse under different input energies. The results show that there exists an energy limit for the molecular alignment. The optimal molecular alignment and anti-alignment degree will never increase with the increase of the laser energy when the input laser energy exceeds the energy limit. Besides, below the energy limit, the molecular optimal alignment (or anti-alignment) degree by using a shorter pulse (its duration is shorter than 100 fs) will be about the same when keeping the input laser energy constant (different pulse duration and the peak power are chosen), especially at a lower temperature of the molecular assembly.
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