This PDF file contains the front matter associated with SPIE Proceedings Volume 13182, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

In this study, we employ the distributed phase screen method to simulate the transmission of Autofocusing Airy beams (AAB) with a new kind of power-exponent-phase vortex (NPEPV) through oceanic conditions, including the effects on light intensity and scintillation. We observe that during the oceanic transmission of an AAB with NPEPV, the beam's main ring progressively divides into fan-shaped sections that match the number of topological charges, with the ring maintaining its integrity without splitting at higher power indices. Furthermore, the scintillation index for AAB with NPEPV decreases as the topological charge increases, up to 400 m. Beyond this distance, the beam structure is significantly disturbed and the relationship between scintillation index and topological charge becomes irregular. Additionally, a higher power index results in a smaller scintillation index slope over the transmission distance and smoother fluctuations in the scintillation factor. At the same transmission distance, a smaller girdle radius leads to a lower scintillation index for AABs with NPEPV.

Nowadays, the application of active detection technology becomes more and more widespread. It is required to separate the transmitter and receiver. To achieve such separation, synchronization between the transmitted and received signals is necessary. A common matching method is to send a synchronization signal, which requires additional channels. Or it can be implemented through protocols, such as using starting bits, which fails when part of the signal is lost or submerged by noise. In this paper we propose a new matching protocol using aperiodic coding and modified edit distance, which requires less data storage and may be easily integrated into the detector. The method is verified within a ghost imaging system, with separated transmitter and receiver. Even if the echo intensity is as low as the level of few photons, it still works well.

Generating self-accelerating pulses and solitons simultaneously is often challenging since nonlinearities tend to disrupt the self-accelerating structure of the pulses. The linear and nonlinear propagation of the Airyprime pulse with spectral quadratic phase modulation (QPM) is investigated. For the linear case, the QPM cancels or superimposes with the group velocity dispersion, depending on whether the two are of the same or opposite sign. For the case of nonlinear propagation, the high-frequency and low-frequency components of the Airyprime pulse show different propagation states and are independent of each other. Thus, simultaneous output of soliton and self-accelerating pulses (SAPs) can be achieved with the selection of suitable QPM parameters. Moreover, one of the two outputs can be selected by filtering half of the spectrum. The QPM parameter can effectively regulate the soliton emission angle and the propagation distance required for the SAP reformation. We believe that it will not only deepen the study of nonlinear dynamics of Airyprime pulses but also provide new ideas for soliton and SAP generation.

Correlated multiple sampling (CMS), an extension of correlated double sampling (CDS), is a very popular technique for denoising the readout chain of image sensors. In this paper, a mathematical readout model of CMS is established, and the readout noise is simulated. Combined with the simulation results and experiments, the influence of three CMS parameters on the noise is analyzed: number of sampling, sampling period, and the interval between the last reset sampling and the first signal sampling. The experimental results are in good agreement with the simulation results, showing how the CMS parameters affect the noise. Finally, combined with the experimental results, an optimal configuration is selected, and an ultra-low noise of 0.46e- is obtained.

The development of all-fiber Doppler wind lidar has garnered significant interest in mobile wind detection due to its compact design and reliability. We have developed a mobile Doppler wind lidar (MDWL) suitable for individual equipment applications. Based on the theoretical model of the signal-to-noise ratio (SNR) function, we determine the system parameters to strike a balance between detection capability and compactness, specifically tailored for portable lidar instruments. The detection range of more than 2km is achieved with a pulse energy of 20μJ and a pulse width of 400ns. We integrated two wind field inversion methods—VAD scanning detection and forward horizontal detection— into a proposed intelligent operation algorithm. Through time-frequency analysis, we successfully measured the precise distance to hard targets and obtained wind field results with a single lidar, highlighting the potential for multifaceted information detection. The experiments in urban areas further validate the effectiveness of wind detection methods.

Multi-modal sensors can provide more useful and detailed information. Visible images contain a large amount of detail and texture information. Short-wave infrared imaging has a strong penetrating ability and performs well in complex environments. Polarization detection can obtain polarization information which conventional imaging techniques cannot obtain. In this paper, we construct a dual-band polarization imaging sensor that can be used for visible light, short-wave infrared, and polarization imaging. An image registration algorithm is applied to obtain multi-modal images of the same scene. Multiple image fusion methods such as Laplacian pyramid transform (LPT), Intensity-Hue-Saturation (IHS) transform, principal component analysis (PCA), and pulse-coupled neural network (PCNN) are compared and analyzed with a qualitative assessment of subjective and objective metrics. Based on the experiments, the advantages and disadvantages of different fusion methods are discussed.

Infrared image super-resolution reconstruction technology can improve image resolution without changing the hardware of the imaging system, and has high cost-effectiveness. In this paper, a super-resolution reconstruction method based on convolutional neural network and pixel shuffle is proposed for the variable length infrared image sequences. Global residual learning and local residual block are introduced to accelerate the convergence speed of the network. Non-local residual block, progressive fusion residual blocks and pixel shuffle module are used to learn the long-distance time information and rich spatial information of infrared low-resolution image sequences. In addition to the fidelity evaluation indexes commonly used in current representative super-resolution reconstruction methods, we also introduce visual perception and image sharpness evaluation functions for perceptual evaluation. The network in this paper is trained and tested on real-world multi-frame infrared images. The experimental results show that the proposed method has advantages in obtaining better perception quality.

Improving detection accuracy of low-resolution objects remains a challenging task in the field of photoelectric detection, and image super-resolution (SR) is one of the vital processing methods that contribute to improving detection accuracy. Current infrared SR algorithms are mostly based on fixed integer scaling factors, but in practical applications, the ability to represent images at arbitrary resolutions is crucial for object detection. This study proposes a method named YOLOArbSR based on arbitrary-scale SR reconstruction to address the problem of low detection accuracy in low-resolution shortwave infrared images. We optimized the super-resolution algorithm to accommodate arbitrary scale factor for detecting infrared targets using the implicit representation function. Furthermore, we introduce a local texture estimator (LTE) and tune the network hyperparameters. Experiments on the practical dataset obtained from the experimental infrared system show that our proposed method is superior to existing technologies in improving the accuracy of infrared detection.

Satellite laser communication has been world wide studied for the advantages of high communication rate, light-weight terminal and good beam pointing performance. With the increased demand for satellite laser communication networking, it’s necessary to improve the capture performance of the terminal. In this paper, the beacon-less dual beam capture method is proposed. Comparative analysis was conducted on scanning time and coverage rate between single and double beam (DBS) uncertain areas scanning. The simulation results shown that dual beam scanning can shorten the capture time by at least half, and the improvement effect becomes more significant with the increase of uncertain field (UF), and with the increase of UF, the effect becomes more pronounced. Furthermore, when the uncertainty region is relatively smaller, the resistance of DBS to vibration is better than that of SBS, but this performance will decrease with the increase of UF.

To propose a measurement method for the verticality of deep hole based on monocular vision.The coordinate conversion matrix of pentaprism circumferential scanning is derived, and the circumferential scanning trajectory and characteristics of the targets are simulated and analyzed .Based on the visual axis, the normal direction of the measurement datum is constructed to accurately compensate the error between the camera visual axis and the tube datum.For the simulated tube with a radius of 956.21mm, a thickness of 999.55mm and a verticality of 0 mm, the verticality accuracy measured by the system can reach 0.03mm.The actual test shows that the method of measuring the verticality of deep hole with monocular vision is effective and feasible. The system is easy to operate and highly automated, which can greatly improve the measurement efficiency and ensure the measurement accuracy. It is of great significance to the production and measurement of deep holes in nuclear tube sheet.

In this paper, we study the changes in the dynamic state and bandwidth of spin-polarized vertical-cavity surface-emitting lasers (VCSELs) in the free-running state when they are injected by another spin-VCSEL in different working states. The study theoretically investigates the chaos interval, bandwidth change, and complexity change concerning continuous wave (CW) injection, period-one (P1) injection, and period-two (P2) injections. The simulation results indicate that modifications to the external control parameters significantly affect the dynamic range of the spin-VCSEL, leading to an expansion of the chaotic range as the complexity of the external injection terms increases. Finally, by carefully modifying the external control parameters, it becomes feasible to operate the spin-VCSEL in a desired state.

The phase synchronization accuracy of modulated baseband signal in high-speed space optical communication directly affects the error rate and ranging performance of the communication system. At present, high-speed modulation baseband signal have problems such as low phase synchronization accuracy and complex hardware implementation. This paper proposes a high-speed modulation baseband signal phase synchronization algorithm based on FPGA. The phase of high-speed baseband signal transmission clock is adjusted in real time through closed-loop control to realize the phase synchronization of I and Q high-speed signals. The experimental results show that the phase synchronization accuracy of the high-speed optical modulation baseband signal with code rate of 5Gbps is less than 5ps; The communication sensitivity is better than -46dBm, and the ranging accuracy is better than 3mm. Compared with traditional methods, synchronization accuracy, communication sensitivity and ranging accuracy have been significantly improved, and low hardware complexity.

We investigate the spatio-temporal propagation of the chirped Gaussian within the graded-index (GRIN) multimode fibers (MMFs). The process of the dispersive waves (DWs) formation can be influenced by the spatial self-imaging effect caused by the periodic oscillating effective beam area within the GRIN MMFs. In addition, the Raman-induced frequency shift (RIFS) effect of the Gaussian pulse is also influenced by the compression factor of the self-imaging effect, and the positive chirp parameter of the Gaussian pulse. Therefore, the emission of the DWs can be handled resultfully by changing the compression factor of the self-imaging effect within the GRIN MMFs. The results can make a further understanding of the RIFS and the generation of DWs within the GRIN MMFs, and lead an important guidance for the experiment.

The single-pixel imaging technique has garnered widespread attention and research due to its low requirements on detector resolution and equipment cost. In this study, a laser point scanning single-pixel imaging system is constructed. It utilizes a grating installed in front of the detector to capture a single-frame deformed fringe pattern, combining Fourier transform profilometry with three-dimensional phase mapping to ultimately achieve three-dimensional data acquisition. Following the calibration of the system, the positions of each light ray are calibrated using the intrinsic and extrinsic parameters obtained through camera calibration. Consequently, this paper proposes a single-pixel three-dimensional reconstruction method based on three-dimensional phase mapping, establishing a correlation between three-dimensional points and phases to realize three-dimensional phase mapping. Experimental results demonstrate that the model can achieve high reconstruction accuracy, presenting a novel solution for the field of single-pixel three-dimensional reconstruction.

Average speckle size is an important statistical parameter representing the lateral profile feature of laser speckle, which has an impact on the measurement of in-plane displacement of scattering object. In this experiment, a measurement system of in-plane displacement through scattering object has been setup. By varying propagation distance and scattering surface diameter, laser speckles are collected by CCD camera and autocorrelated to obtain the estimation values of average speckle size, and then the in-plane displacements are measured by digital image correlation method. Afterward, the influence of average speckle size on in-plane displacement measurement is discussed, and the result shows that the larger the average speckle size is, the greater the measurement error is, and the smaller the measurement limit is, which has a certain reference value for practical applications in the displacement and deformation measurement of objects.

The traditional star sensor uses the pupil function of the lens to produce circular aperture Fraunhofer diffraction to form the diffuse spot, then enlarges the diffuse diameter by defocusing, and finally uses Gaussian fitting to determine the centroid of the star point. Compared with the traditional star sensor, this paper designs a new star location method based on rectangular hole Fraunhofer diffraction. The method first changes the optical system structure of the star sensor, so that the pupil function produces Fraunhofer diffraction image on the focal plane of the optical lens at infinite distance, and then directly determines the centroid of the star point through Gaussian fitting. Finally, the reliability of this method is verified by simulating random error. The Gaussian fitting algorithm of the new star sensor has higher accuracy, less computation burden and higher accurate reliability. Experiments show that the localization accuracy of this method can reach 0.007 pixels.

We provide a novel method to extract the loss characteristic of the whispering gallery mode (WGM) microcavities using optical frequency domain reflectometry (OFDR). We demonstrate the modified OFDR system in this measurement and the Q-factor of the microcavity is obtained accurately from the backscattered signals. Compared with the transmitted measurement method, the OFDR result can clearly show the optical path of the resonance mode in the spatial domain, and there is no need to distinguish the resonance from the complex transmitted spectra. This method is also demonstrated to be suitable for measuring polarization-sensitive devices.

Lasers used in optical interconnects in data centers require electro-absorption modulators (EAMs) with low energy consumption and cost. In this study, we designed and optimized EAM through numerical simulation. By optimizing the doping concentration in the separate confinement heterostructure (SCH) layer, we achieved an increase in the maximum extinction ratio (ER) from 44 dBm to 64 dBm and a reduction in the driving voltage from 3.8 V to 2.9 V. These results provide theoretical support for further reducing the energy consumption and cost of EAM in optical communication, especially in the current era of escalating data volume.

In object detection tasks, when facing situations such as low contrast, occlusion, multiple overlapped targets, and changes in lighting, the detection performance of pure visible light (RGB) images or infrared (IR) images for object detection is not good. Combining image information from both visible light and infrared modalities can result in higher accuracy and more robust object detection under these challenges. The key to building an object detector based on the visible light and infrared modalities is how to merge the two modalities to obtain a more effective feature representation. For this purpose, we first constructed feature fusion module and feature enhancement module to effectively fusion and enhance the feature representations of the two modalities of visible light and infrared. Second, by combining the Bottleneck Attention Module (BAM) and the feature fusion and enhancement module, a dual-spectrum object detection network is constructed. Finally, we conducted experiments on the LLVIP and FLIR datasets, achieving mean Average Precision (mAP) of 46.2% on FLIR and 68.1% on LLVIP, surpassing the results of other recent methods. Experimental results showed that the dual-spectrum object detection network constructed in this paper effectively improved the performance of object detection.

When running a panoramic video stitching system on a UAV, he low computing power of the embedded system loaded on the UAV and the changing scenes during the flight cause a large color difference in the panoramic picture. Therefore, based on the characteristics of the UAV panoramic stitching system, we propose a novel algorithm, which has strong real-time performance, almost zero computation, and can adapt to drastic scene changes, compared with traditional algorithms. This algorithm providing a visually pleasing panoramic video color correction effect on the UAV. The experimental results show that the algorithm can effectively eliminate the color difference between the stitched images when running on the UAV, and the computing resource consumption is almost unchanged compared to when no color correction is performed.

Two-photon fluorescence lifetime microscopy (TP-FLIM) is a powerful quantitative imaging technique that that can characterize and analyze the microenvironment changes of biological samples in the fluorescence lifetime dimension. It is not affected by factors such as excitation light intensity, sample bleaching, and fluorophore concentration, and has the advantages of high sensitivity and resolution. Therefore, it has extensive applications in biomedical research, disease diagnosis, and other fields. Second harmonic generation imaging (SHG) possesses the unique characteristics of high spatial resolution and imaging depth inherent in nonlinear optical imaging. SHG occurs in non-centrosymmetric structures, a property exhibited by collagen tissue in biological organisms. Consequently, SHG has been employed for specific tissue structure imaging. This paper combines TP-FLIM and SHG technologies to investigate pathological lung sections. Vector analysis of TP-FLIM is applied to analyze the fluorescence lifetime data of lung collagen fibers. Through TP-FLIM and SHG technologies, the lifetime of collagen fibers in the sample can be calculated and the collagen fiber tissue and non-collagen fiber tissue in the lung tissue sections can be clearly distinguished. This provides a new direction and possibility for indepth understanding of pulmonary fibrosis and other pathological mechanisms related to collagen fiber diseases, offering new insights into pathology and provisional diagnosis.

Under the background of the era of vigorously promoting green energy-saving buildings, infrared imaging inspection technology, as a non-contact nondestructive testing means, has been widely used in the field of building energy efficiency. However, due to the existence of various influencing factors, so that the infrared imaging instrument measured temperature and the real temperature of the surface of the object deviation, its measurement results can only do qualitative judgment and can not do quantitative analysis, resulting in the application of infrared technology in the field of building energy efficiency limitations. The article is based on the application of infrared technology and the principle of temperature measurement, through the multi-factor comparative experimental testing and analysis , assess the impact of different building materials, detection distance, reflectivity, reflective temperature and building orientation and other factors, which is conducive to improving the accuracy of the application of infrared imaging technology in the field of construction, and to provide engineers with a relatively accurate and feasible application of the guide to the actual engineering applications to do reference.

In order to improve the wavelength strobe speed and band strobe width of optical add/drop multiplexer in optical fiber communication system, a fast tuning optical add/drop multiplexer based on piezoelectric control fiber Bragg grating is proposed. The application of fiber-optic communication was analyzed and simulated experimentally. The system controls the modulation voltage of 0-160V to achieve sweeping over the bandwidth range of 1548.325-1553.248nm. Through simulation analysis, the effects of different parameters on the peak reflectance and reflection bandwidth of the reflected light of the system are discussed. The experiment uses PZT to control the wavelength gate of FBG. The results show that the loading curve is basically consistent with the unloading curve and the linearity is good, which can realize fast narrowband band-pass control. At the same time, the 1548.325nm signal light was tested, downloaded and passed through, and the experimental results met the design requirements. The structured optical add/drop multiplexer has the advantages of fast control speed, high linearity, and the like, and has certain application value in the optical fiber communication optical add/drop multiplexer.

In this paper, it is difficult to realize the rapid measurement of the whole tower when laser long-distance non-contact measurement is used in the detection of bolt looseness of overhead transmission line towers. Firstly, the existing tower bolt loosening detection technology is briefly introduced, and the existing problems in realizing the rapid detection of the bolt looseness state of the whole tower are pointed out. Then, the vibration detection principle of bolt looseness is expounded, and the relationship between the measuring point and the bolt loosening position is obtained according to the analysis of the vibration data under different measurement points of a tower structure, and a method for rapid detection of bolt looseness of the tower is proposed, which lays a research foundation for the rapid detection and intelligent identification of the bolt connection state of the whole tower in the future.

In the current optical remote sensing field, it has continuously evolved into a multi-layered and multi-perspective observation system. Faced with the complexities of observation tasks, diverse observation methods, and the refinement of observation targets, there is a need for more in-depth research on denoising of remote sensing images. Traditional denoising algorithms often produce denoised images with overly smooth edge textures, leading to the loss of small targets within the images. Therefore, addressing the aforementioned issues, this paper proposes an improved denoising algorithm based on the Transformer network structure. This algorithm employs attention operations across channel dimensions and utilizes feature recalibration. This allows the model to determine the importance of various feature channels, thereby avoiding the significant computational overhead brought about by the traditional Transformer's self-attention enhancement in spatial dimensions. Moreover, the algorithm utilizes a U-shaped denoising module, which effectively reduces the semantic gap between image feature mappings, resulting in the restoration of better image features. The experiments indicate that when tested on remote sensing image datasets, the proposed algorithm outperforms current representative algorithms in both subjective and objective evaluation metrics. While effectively removing image noise, it also better preserves edge details and texture features, achieving superior visual results.

By using wavelength selection methods to eliminate irrelevant and redundant information from near-infrared spectroscopy data before modeling, the performance of the apple sugar degree prediction model can be improved. However, there are many shortcomings in commonly used single-wavelength selection methods. This paper combines the competitive reweighted sampling (CARS) algorithm, the successive projection algorithm (SPA), and the genetic algorithm (GA), which are three primary single-wavelength selection methods, to merge the wavelength subsets obtained from them. These subsets are then combined through intersection and union fusion, resulting in 8 Venetian wavelength subsets. A fructose prediction model for apples is established by combining them with the Ridge Regression model. The results show that the number of wavelength subsets obtained by the preferred CARS∪SPA method is 74, accounting for 14.4% of the total wavelengths. Its R² _p is maximum at 0.952, and the minimum RMSE_p is 0.036. This indicates that the wavelength selection method of CARS∪SPA reduces the multicollinearity of spectral data, effectively utilizes complementary information in the wavelength variables obtained by CARS and SPA methods, and enhances the robustness and accuracy of the model. The research work can provide theoretical basis for the rapid grading of apple quality and the development of related detection devices.

Evolution of the model basing on the nonlocal response functions has been accessed according to the (2+1)d schrödinger equation in cartesian coordinates. This paper presents the singular laguerre-gaussian beams modulated by the airy functions in free space. Their propagation characteristics have been discussed with split-step fourier method. It is possible to solve process the space-time multiple beams propagating in the medium using the superposition principle. Even more, it provides the theoretical basis for all-optical control technology.

Spectral reflectometry is widely used to measure the crucial parameters such as thickness and refractive index of film, surface morphology and grating constant in a convenient way. In this work, we focus on the measurement of air gap between two parallel plates. The transfer matrix method (TMM) and rigorous coupled-wave analysis (RCWA) are independently used to build the theoretical model of the air gap with micro and nano scale between two parallel plates, and then we compare the results. Through the simulation of reflectance spectrum based on optimized TMM. The influence of interfacial roughness of multilayer structure is analyzed. Then we introduce a merit function which includes air gap and interfacial roughness and then optimize them using genetic algorithm to solve the measured air gap value. The absolute measurement of air gap thickness and subsequent displacement measurement result indicate that our method has the advantage of high precision, resolution and stability.

The indirect time-of-flight imaging system possesses the characteristics of high real-time, high integration, and low cost, so it has a wide range of applications. However, the different reflectivity of the measured object will affect the change of the received signal, resulting in different degrees of depth error in the system. In this paper, we analyze the influence of reflectivity on the system, establish the reflectivity-related error model, and propose the error calibration method. The proposed method estimates the approximate reflectivity of the measured object through the range and amplitude information output by the system at first, Then the parameters of the error curve model are changed according to the obtained reflectivity, and the corresponding compensation is obtained. This method can select the corresponding compensation amount for objects with different reflectivity. The experimental verification shows that the method in this paper has a good effect on the calibration of reflectivity-related errors.

At present, the wavelength range operated by optical fiber communication is 1530-1570nm, which can no longer meet the further needs of users for bandwidth. Therefore, it is necessary to develop a broadband optical fiber amplifier to improve the bandwidth and capacity of the optical fiber transmission system. This article proposes a composite structure of bismuth-doped fiber (BDF) and erbium-doped fiber (EDF). Genetic algorithm optimization is used to make the gain bandwidth larger and the gain spectrum flat. Parameters such as doping ion concentrations and fiber lengths of BDF and EDF are optimized to minimize the difference of amplification ratio between the bismuth-doped fiber and the erbium-doped fiber as much as possible. The results show that the amplifier can amplify the signal with a bandwidth of 1250-1650nm,greatly improving the wavelength range of optical fiber communication.

Polarized imaging is widely used for separating specular reflection and diffuse reflection. By introducing the Bidirectional Reflectance Distribution Function (BRDF), the polarized characteristics of materials can be characterized. The polarimetric BRDF (pBRDF) describes the material's polarization properties through Mueller matrix-valued functions related to geometry, texture, and reflectance. Addressing the issue of inaccurate representation of surface reflection components for metal materials due to roughness and complex refractive index, this paper proposes a metal pBRDF modeling method. The method models the BRDF of the metal surface as a combination of single specular reflection and multiple inter-reflections. Experimental validation through Mueller matrix reconstruction demonstrates the accuracy and feasibility of this model.

A simultaneous measurement method of 3D small Angle laser based on PZT feedback compensation is proposed. A single right Angle prism is used as the 3D Angle sensor, and the collimated laser beam is incident on the beam-splitting film coated beam-splitting surface. The 3D Angle change of the moving platform where the sensitive element is located is calculated by the position change of the two beams of light on the photoelectric position sensitive detector after beam-splitting. The reflected beam is used to measure the tilt and pitch Angle. The beam reentering through the prism after transmission is used to measure the rolling Angle. To solve the problem of limited moving distance of the platform to be measured and the influence of light drift caused by pitch Angle crosstalk in rolling Angle measurement, a PZT piezoelectric ceramic feedback compensation unit is introduced to ensure that the measuring beam is always located in the central sensitive region of the position sensitive detector, improve the stability and measurement accuracy of the system, and realize high-precision real-time measurement of the rolling Angle of the platform to be measured with a larger moving distance. The feasibility of the scheme is verified by theoretical analysis and experiment. This method has the advantages of simple structure of sensitive unit, strong anti-interference ability, high precision, low cost and small size.

High-speed and energy-efficient cryogenic electronics in supercomputers and quantum computers have emerged as the most competitive alternative in the next generation of information processing systems. Specifically, the challenge of establishing broadband, energy-efficient data transmission from cryogenic electronics to room temperature environments has emerged as a significant bottleneck. Electro-optic data links based on the thin-film lithium niobate (TFLN) electro-optic modulators (EOMs) operated at 38.5 K hold the potential to breakthrough this limitation by providing high bandwidth and low heat load for signal readout in cryogenic electronics. In this article, the performance of a TFLN EOM was examined at room temperature and cryogenic temperature, respectively. The results show that the system achieves a bandwidth of 7.6 GHz at 38.5 K, which is 7% higher than the bandwidth achieved at 298 K. A data transmission rate of 15 Gbps using non-return-to-zero (NRZ) encoding supporting error-free data transmission at 38.5 K to the error detector at 298 K is demonstrated as a viable solution for cryo-computing.

The water track laser Doppler velocimeter (WTLDV) reported by our group recently emits laser to sense the moving velocity of the carrier in forward direction relative to water in underwater environment. And SINS/WTLDV integrated navigation system is a promising underwater navigation system with high concealment and autonomy. In this study, a calibration system for WTLDV combining the pitch independent laser Doppler velocimeter (PILDV) and the towing tank is presented to obtain the velocity measurement accuracy of WTLDV in water. The heading angle of PILDV mounted on the cart should be calibrated firstly using the distance observation-based method. The three main contributions of uncertainty in the calibration system are discussed. The expanded uncertainty of the calibration system is less than 0.11%. one hundred times measurement by PILDV under the same set velocity of the cart indicate that the towing velocity of the cart is unstable so that the set velocity of the cart cannot be used to calibrate WTLDV. The calibration results show that the relative measurement error of WTLDV is less than 2.5% with expanded uncertainty of less than 0.11% in the velocity range of 1m/s to 2m/s. The proposed calibration system can be used in the calibration process for WTLDV, as well as other current profiling sensors, such as the impeller current meter, electromagnetic log and DVL.

This paper presents a study on continuous wave tunable CO₂ lasers, which could be used in good pumping source of optically pumped gas THz laser. A series of comparative experiments to investigate the effects of cavity structure and discharge current on laser tunability and output power was conducted. The wavelength selection of CO₂ lasers primarily achieved by altering the angle of incidence of the blazing grating. Two enclosed CO₂ laser tubes were designed and customized, one was used for external cavity structure and the other was used for semi-external cavity structure research. Using the semi-external cavity structure, 78 lines was obtained at the range of 9-11μm, and achieved 60.7 W of laser output power at a wavelength of 10.59 μm. A beam quality factor of M² = 1.68 was measured using the traveling 90/10 knife-edge method.

We have built a low repetition frequency ytterbium-doped mode-locked fibre laser by combining the nonlinear polarization rotational effect with a long single-mode fibre and achieved a low repetition frequency mode-locked pulse output with a pulse repetition frequency of 268.8 kHz, which is experimentally proved to be highly stable and can be used as an ideal seed source for fibre amplifiers, which is a compact laser that can be used for many important applications.

The optical fiber winding structure provides a long-distance data link for the optical fiber optic guided missile (FOG-M). Based on the stress analysis, we established a brand new theoretical model to calculate the strain distributed of standard optical fiber winding structure. An iterative formula is obtained, which can be used to calculate the axial strain of each layer in winding process. Calculation results show that strain decreases continuously layer by layerfrom the outside to the inside layers and gradually converges to a constant after a couple of layers. Using the distributed Brillouin optical time domain analysis (BOTDA) technology, the distributed strain of fiber winding structure in different layers is measured. Experimental results agree with theoretical calculation. This research may provide an important means for the optimization of fiber winding process in the future.

Lead sulfide colloidal quantum dots ( PbS CQDs) offer the unique advantages of tunable bandgap, cost-effectiveness, and ease of processing. These characteristics make PbS CQDs an ideal candidate for the development of near-infrared (NIR) photodetectors, with promising applications in diverse fields such as fiber optic communication, biomedical imaging, and national defense. In this study, NIR photodetectors employing indium gallium zinc oxide (IGZO) as the carrier conductive layer, PbS CQDs as the photosensitive layer, and pentacene as the functional enhancement layer are fabricated and systematically studied. Comparative analysis unveiled That the p-type semiconductor property of the pentacene is leveraged to increase the photoresposne of the PbS CQDs-IGZO NIR photodetectors. This work not only sheds light on the structural advancements of photosensitive field-effect transistors but also provides valuable insights into optimizing their performance.

In order to capture the standard color images from the ocean surface with a digital camera, we propose a new colorimetric modeling method named “Two-step training and modeling”, so that the color conversion model from the camera RGB space to the CIEXYZ space can be established, and standard color images of the ocean surface can be obtained by the camera. In the theory, the color conversion models using polynomial transforms were introduced, and in the methodology, the colorimetric calibration method of the camera for the ocean imaging was put forward. In the first step experiment, a group of training samples were captured by the camera from the Colorchecker-SG cards illuminated under natural sunlight, and the color conversion models from RGB to CIEXYZ were established by means of different polynomial formulas. In the second step experiment, the supplementary training samples were captured by the camera from the real surface of a certain sea area in China illuminated under natural sunlight, and the color conversion models of different polynomial formulas for the ocean surface image were established. The experimental results show that by using the method of “Two-step training and modeling”, the significant improvement of the color conversion accuracy for the ocean surface imaging can be achieved.

Electron transfer across heterostructure interfaces plays a pivotal role in the functionality of modern electronic and optoelectronic devices, such as photocatalysts, solar cells, and phototransistors. However, interaction with ultrafast lasers could trigger a nonlinear optical response within individual materials to compete with the interfacial photocurrent in the heterostructure. Distinguishing the interplay between interfacial photocurrent and surface nonlinear photocurrent is challenging yet interesting. Herein, terahertz (THz) emission spectroscopy is employed to demonstrate the synergistic interaction between interfacial charge transfer and nonlinear photocurrent (photogalvanic effect in MoS₂ and photon drag effect in graphene), thereby enhancing THz radiation in the graphene/MoS₂ heterostructure compared with pure MoS₂ and graphene. Interestingly, the contribution of interlayer charge transfer to the THz radiation gradually increases as the pump fluence increasing from 0.14 mJ/cm² to 1.70 mJ/cm². Our work offers an effective way to actively control the interface effect of heterostructures, potentially leading to advances in the utilization of graphene-based heterostructures in photonics and electronics devices.

The article proposes a novel all fiber vector magnetic field sensor structure based on magnetic fluid (MF) and side-polished eccentric-core fiber structure. The basic connection structure of the sensor head consists of an eccentric-core fiber (ECF) fused in the middle of two single-mode fibers (SMFs). The eccentric-core fiber (ECF) was side-polished to destroy the circular symmetry of the fiber. We encapsulated magnetic fluid (MF) on the surface of optical fiber structure by using capillary and combine the anisotropic distribution characteristics of MF to achieve vector magnetic field sensing. The research results indicate that the fiber structure shows a magnetic field intensity sensitivity of -0.381 dB/mT within 44~62 mT, with a maximum direction sensitivity of 519 pm/°. The sensor proposed in this paper adopts all-fiber structure, which is simple to manufacture and small in size, and has potential application prospects in many fields.

CFRP materials are widely used in aircraft manufacturing, and ensuring the safety and reliability of these materials is crucial for flight safety. The acquisition of interlaminar stress can effectively evaluate material performance. This article introduces a CFRP interlaminar stress quantitative measurement method based on the stress birefringence effect of Fiber Bragg Gratings. This sensor converts the refractive index change of fiber stress birefringence into the bandwidth and peak splitting changes of the grating spectrum, simplifying the experimental setup and achieving real-time monitoring of CFRP interlaminar stress. The interlaminar stress of the CFRP laminate in this article significantly increases during the cooling stage of thermal curing and ultimately remains at a stable level of 17.6 N/cm. Sensitivity of the interlaminar stress sensor is 9.61 pm/(N/cm). This article provides an effective method for real-time monitoring of CFRP interlaminar stress throughout the entire curing cycle. It also demonstrates the feasibility of providing data support for CFRP manufacturing process improvement through experimental verification.

With the advancement of minimally invasive surgery (MIS) and interventional therapy robots, the lack of direct perception of the contact force between interventional instruments and human blood vessels and tissues by physicians often leads to surgical complications or suboptimal treatment outcomes. Therefore, the development of miniature force sensors for instrument tips has become a hot research topic. This paper introduces a fiber-optic flexible force sensor based on Fabry- Pérot interference (FPI), which can be integrated into the tip of guidewires used in minimally invasive surgery. The performance of the designed sensor was validated through simulations and experiments, demonstrating its excellent capabilities. The results indicate the potential of this sensor for real-time force monitoring in minimally invasive interventions.

We propose an approach for implementing spike-based all-optical fast neuromorphic exclusive OR (XOR) operation using a single vertical-cavity surface-emitting laser (VCSEL). Based on the polarization mode competition in the VCSEL under the influence of dual-polarization optical injections, the XOR operation is realized. Here, the inputs for the logic operations are concurrently injected into the orthogonal polarization modes of the VCSEL-neuron in the form of a square wave, achieving high stability and accuracy. The spike-based XOR operation approaches a 0.8 gigahertz (GHz) rate within only one photonic neuron, which is 3.2 times faster than that of the vertical-cavity semiconductor optical amplifier (VCSOA)- neuron. Furthermore, the feasibility of employing the XOR operations in both discrete and continuous tasks has been verified. Our approach aligns more congruently with the processing method of biological neurons for XOR operation tasks, thereby demonstrating great potential for future photonic neural computing.

In order to authenticate the optical transmitter effectively and improve the transmission performance of the optical communication greatly, the paper studies a method of optical transmitter authentication based on group delay estimation. The paper extracts the bispectrum phase information of the optical channel according to the communication frame sequence of the transceiver system, and lists the phase frequency coefficient square matrix of the transmission system to estimate the transmitter group delay characteristic parameters. The simulation results show that, even when the signal to noise ratio (SNR) is 5dB, normalized mean square error (NMSE) of estimated group delay by the bispectrum algorithm can reach -18dB. Compared with the traditional method, the method introduced in this paper show that the group delay estimation method is more effective and has better performance against noise.

Breast cancer is currently the most prevalent cancer among women, and the level of HER2 is one of the important indicators of breast cancer prognosis. In this paper, we propose a fiber-optic biosensor based on surface plasmon resonance (SPR) for rapid and direct detection of HER2 protein using patient plasma. The method utilizes the difference in resonance wavelength shift before and after immunoassay to achieve quantitative detection of HER2 protein. To simplify the bio-modification step and improve the detection efficiency, we used protein G in a one-step reaction with 2-iminothiolane to generate a thiol functional group to form a self-assembled layer on the gold surface of the sensor. We optimized the strategy of immobilizing coating antibody on the sensor surface as well as the antibody concentration, which significantly improved the sensitivity of the biosensor to 0.20666 nm/(μg/mL), a 2.5-fold increase compared to the non-optimized case. Our protocol was able to specifically detect HER2 protein under label-free conditions with a minimum concentration of 1 μg/mL. This study provides an innovative tool and methodology for breast cancer-related research and clinical applications and is expected to promote further development in the field of breast cancer diagnosis.

We study a relatively excellent BHD(Balanced Homodyne Detector)with large bandwidth and low noise pre-amplification, which is different from the specific BHD implementation scheme and can better adapt to the subsequent cascade scheme, thereby achieving the implementation of BHD with specific needs. Specifically, we optimize our BHD performance by compromising various parameters of BHD, focusing on optimizing and increasing BHD bandwidth, and choosing a more reasonable BHD implementation solution. Judging from the test results, the produced BHD has good performance in extracting effective signals. The bandwidth reaches about 2GHz, which meets the requirements of detection applications. It has a high signal-to-noise ratio of 10 dB and a common-mode rejection ratio (CMRR) of 20 dB near the 2 GHz frequency point.

A temperature adaptability improvement method based on long range optical delay system of optoelectronic oscillator is proposed. The optical delay system consists of optical delay line, optical switches and delay fibers. The optical delay line is used to adjust opto-electronic loop continuously, and the optical switches and fibers are used to extend optical path which could stabilize cavity length of optoelectronic oscillator over a large temperature range. The principle and optical path tuning range of optical delay system of phase locked optoelectronic oscillator is theoretical analyzed and experimental verified. Results show that optoelectronic oscillator with 4 km fiber remains stable within 15 ℃ using the optical delay system, while maintaining its phase noise performance. The optical path of optical delay system can be expanded.

In this paper, a microcantilever fiber optical biosensor based on Fabry-Pérot interferometric (FPI) was invented and used for antibiotic sensitivity testing (AST). This biosensor combines a cantilever and the single mode fiber (SMF) to form an FPI. After bacteria attach to the cantilever, their movement causes cantilever vibration, which can be obtained by measuring the change in dip wavelength of the interference spectrum. We used this biosensor to detected Escherichia coli, indicating the vibration amplitude of the cantilever increases with the increase of the number of bacteria fixed on the cantilever. Obtained the minimum inhibitory and bactericidal concentration against E. coli within 30 minutes, validating the rapid AST ability of this biosensor. The microcantilever fiber optical biosensor developed in this paper provides a novel technology for AST.

In this paper, a highly sensitive airway pressure sensor based on Fabry-Perot interference principle is proposed. The sensor is fabricated by metallic silver film, zirconia ceramic casing, zirconia ceramic ferrule, single mode fiber, and copper nickel-plated tailstock, which meet the chemical stability requirements of medical device. The overall model design and local finite element simulation analysis of the sensor are performed. First, the solid mechanics module of COMSOL is used to emulate the distortion of the film at different pressure to obtain the respective sensor cavity length. Second, the reflectance spectra corresponding to different sensor cavity lengths are obtained using the fluctuating optical module of COMSOL. Thus, the correlation between pressure and spectral offset can be derived. The average spectral sensitivity of the sensor under pressure is obtained to be -1.68 nm/KPa. On this basis, the demodulation method of F-P sensor is explored. The spectral peak tracking principle is applied to the wavelength demodulation of reflection spectrum. The cavity length sensitivity of the sensor is calculated -570.197 nm/KPa. By comparison, the spectral sensitivity after demodulation is obviously improved. The sensor exhibits potential applications in the areas of airway pressure measurement and environmental surveillance.

In order to generate the multi-wavelength fiber at 2.1 μm band, a tunable multi wavelength Ho³⁺-doped ring fiber laser based on all-fiber Sagnac interferometer was designed. A 3m long Ho³⁺-doped silica fiber was pumped by a Tm³⁺-doped fiber laser,and then the spontaneous radiation at 2.1 μm band was amplified.In the annular cavity,the Sagnac fiber interferometer consisted of an 8 m long polarization maintain fiber (PMF) and a polarization controller (PC),and the output wavelength at 2.1 μm waveband can be period tuned by the Sagnac interferometer.In experiment,a multi-wavelength laser at 2.1 μm waveband can be got,the output power can be tuned from 1 mW to 15 mW,and up to 6 wavelengths of laser output can be observed.By adjusting the PC in annular cavity ,the output tunable wavelength number can be realized from 1 to 6 at 2.1 μm band.

This article developed a calibration method to evaluate the metrological characteristics of non-amplified nucleic acid quantitative fluorometers, by studying the working principle of non-amplified nucleic acid quantitative fluorometer. Multiple different types of non-amplified nucleic acid quantitative fluorometers were selected for pre-testing and national certified reference materials are chosen as reference. Critical parameters such as indication error, repeatability, and correlation coefficient are selected as test items. The experimental results shows that, the method proposed and reference materials selected can effectively evaluate the metrological performance of the instrument, which is of great significance for the quality control and quantity traceability of non-amplified nucleic acid quantitative fluorometers.

White LEDs with high color rendering are essential in certain color critical lighting applications. However, developing white LEDs with wide spectrum and high color rendering are still a serious challenge. White LEDs with a color temperature of 3000-5000 K are experimentally prepared, with a color rendering index of over 92. The spectrums are continuous in the visible light range, and the luminous efficiency can reach 120lm/W at a working current of 60mA.Based on the mixture of these full-spectrum white LEDs, three full-spectrum white LED samples of different color temperature (3000 K, 4000 K and 5000 K) were mixed. The dimming effect was analyzed by changing with forward current and different combinations. The results showed that the luminous efficacy could be guaranteed to be over 100lm/w and the color rendering index was 92 to 97.

In high-power end-pumped solid-state lasers, traditional Nd:YAG crystals are extremely susceptible to fluctuations in the temperature and wavelength of the pump source due to their narrow absorption line width, causing fluctuations in the output power of the laser. In order to reduce the sensitivity of lasers to temperature and wavelength drift of the pump source, this paper combines Nd:YAG crystals with excellent thermophysical parameters with Nd:GdVO₄ crystals with wide absorption spectrum characteristics. Through a combination of front and rear placement, the front-end Nd:YAG crystal absorbs most of the pumped energy, and the back-end Nd:GdVO₄ crystals are used to supplement absorption of the unabsorbed pumped energy. When the pump source has wavelength drift, the two crystals use complementary absorption methods to keep the absorption efficiency and output power of the laser stable, thereby reducing the effect of the temperature and wavelength drift of the pump source on the laser. Experiments have shown that when the pump power is 95.5 W, this dual crystal combination scheme can achieve absorption efficiency of more than 91.5 % within the operating temperature range of 22 ℃ to 32 ℃ of the pump source, while the stability of the output power is higher than 92.5 %.

In response to improve the measurement accuracy of Multi-Parameter Aerosol Scattering Sensor (MPASS) in detecting fire smoke concentrations, this study proposes a method using dual-wavelength detection technology. Simulation results prove that the proposed method can effectively improve the measurement accuracy. Based on this, the effect of polarization angle on the measurement accuracy is discussed and the optimal polarization angle is selected. This method helps to reduce the false alarm rate of fire detectors.

Aiming at the laser semi-active guidance jamming technology, this paper expounds the principle of laser semi-active guidance technology and the method of jamming it. Starting from the research of gate technology and pulse acquisition technology, this paper analyzes the jamming effectiveness of current laser jamming technologies such as laser angle deception jamming and high repetition frequency laser jamming against seeker pulse acquisition time gate, and lists the improved laser angle deception jamming and high repetition frequency laser jamming technologies.

Mid-infrared quantum cascade lasers (QCLs) are a type of unipolar semiconductor device based on intersubband electron transitions. Control over the emission wavelength of QCLs is important in many applications such as free-space communication, medical diagnosis, and trace gas detection. In this study, we report on non-monotonic wavelength shift of mid-infrared QCLs at different temperatures. Our QCLs were fabricated based on lattice-matched InGaAs/AlInAs/InP superlattices grown by metalorganic chemical vapor deposition (MOCVD) technique. By strictly controlling the growth conditions, epitaxial wafers with high interface quality structures were fabricated. Under pulsed operation with 300 ns pulse width and 80 kHz repetition rate, our fabricated QCL with a cavity length of 4 mm and a ridge width of 13 μm emitted 28 mW peak power. As the temperature increased from 78 K to 285 K, the lasing wavelength showed a redshift from 9.27 μm to 9.40 μm first and then a blueshift from 9.40 μm to 9.36 μm. This non-monotonic wavelength shift suggests that, besides temperature-dependent refractive index, extra factors such as mode competition within the laser cavity likely affect emission wavelengths of QCLs.

Interferometer is the core component of the Fourier transform infrared spectrometer (FTIR). The scanning accuracy and stroke of the moving mirror directly affect the signal-to-noise ratio (SNR) and resolution of the instrument. In order to obtain high-quality spectra, a double-moving mirror swing interferometer with compact structure and small size was designed. Through modeling and analysis of the interferometer, the optical path difference (OPD) expression of this interferometer was obtained. The relationship between the optical path scanning speed and the swing speed of the swing arm was analyzed, and the impact of speed fluctuation on the SNR of the spectrum was pointed out. A nonlinear PI controller based on a disturbance observer was proposed to control the rotary voice coil motor (RVCM), and the controller was simulated and verified. The results prove that the speed stability of the optical path scanning system is higher than 99%, which effectively reduces the impact of external disturbances on the system.

In view of the shortcomings of the traditional transmission line tower bolt loosening detection method, this paper firstly introduces the research background and the existing problems of the existing detection methods, proposes the technology of using long-distance laser vibration measurement device for tower bolt loosening detection and identification, expounds the principle of bolt loosening laser vibration detection, and the basic composition of laser vibration measurement device. In order to improve the recognition accuracy of bolt looseness detection in the tower, the MFCC (Mel-scaleFrequency Cepstral Coefficients) feature extraction algorithm was used to construct the vibration feature model of bolts in different tightness states by combining the GMM-UBM (Gaussian Mixture Model-General Background Model) model, and the clustering characteristics of bolts in different tightness states were analyzed, the clustering characteristics of bolts in different tightness states were obtained, and the identification program was developed. After testing, the accuracy of loose identification of tower bolts ≥ 93%.

Quantum dots (QDs) is widely used in the display field due to its excellent photoelectric properties and relatively good stability. The patterning of QD is an important part of solid state integration of high precision QDs optoelectronic devices. However, traditional patterning techniques either degrade material properties or have complex processes. In this study, selective electrophoretic deposition (SEPD) was used as a patterning strategy, and polymer additives were added to the QD ink to improve the deposition morphology and achieve efficient and non-destructive patterning.

A differential-unwrap-integral-regression-extension (DUIRE) algorithm is proposed to improve the dynamic range of Φ -OTDR system. By applying differential and integral operations, the π -phase constraint can be alleviated, and then the upper limit of the system’s dynamic range can be improved. Through empirical mode decomposition (EMD) operation, the phase noise level is reduced, thereby extending the lower limit of the dynamic range. The experiment results show that compared with the traditional algorithm, the DUIRE algorithm is improved by 1.93 times on the maximum measurable strain (MAMS), and on phase noise level, the DUIRE is reduced by 5.64 dB rad / √Hz @1 kHz.

The soliton-sinc pulses are a recently proposed new type of pulse that has the properties of the Nyquist pulses and the solitons. The soliton-sinc pulses are robust to nonlinear signal distortions due to the preservation of the same oscillatory structure as the Nyquist pulse. The soliton-sinc pulses hold fascinating promise for applications in optical communications, and the latest research in optical cavities has realized soliton-sinc pulses. We investigate the propagation dynamics of soliton-sinc pulses in the presence of higher-order effects, including fourth-order dispersion, self-steepening, and Raman effects. Numerical results show that under normal fourth-order dispersion, one radiates dispersion waves, while under anomalous dispersion the soliton-sinc pulse splits. The intensity of the radiative dispersion wave and the intensity of the pulse splitting is governed by the bandwidth of soliton-sinc pulse. In the presence of self-steepening effects, the number of soliton-sinc pulse splits can be effectively controlled by the bandwidth. Simultaneously, under the influence of the Raman effect, the Raman effect becomes more obvious with smaller bandwidth restrictions. These results demonstrate the propagation dynamics of soliton-sinc pulses under higher-order dispersion and nonlinear effects, which have practical applications for pulse control and optical communications in optical fibers.

Traditional passive radiative cooling materials typically exhibit high solar reflectance and mid-infrared emissivity, delivering excellent cooling performance when in direct contact with the surface of an object. However, when the surface of an object is not in contact with radiative cooling materials, the heat emitted by the object first passes through the air with a lower thermal conductivity and is then transferred to radiative cooling materials. Subsequently, the radiative cooling materials transmit the thermal radiation to outer space. This process significantly increases the thermal resistance of the radiative system, thereby impeding the dissipation of heat from the object. To enhance the performance of non-contact radiative cooling, radiative cooling materials must possess high solar reflectance and mid-infrared transmittance. While blocking solar radiation, they should enable the thermal radiation emitted by the object to pass directly through the infrared-transparent material. In this study, we prepared porous poly(4-methyl-pentene) (P-TPX) films with a solar reflectance of 88.6% and an infrared transmittance of 88.11%, aiming to achieve efficient non-contact radiative cooling. Under identical conditions, the P-TPX film, which is transparent to infrared radiation, exhibited superior cooling performance compared to the Poly(vinylidene fluoride-co-hexafluoropropene) porous (P-P(VdF-HFP)) film, which has higher infrared emissivity. The temperature difference between the two films reached up to 4.5 °C, indicating that the infrared-transparent P-TPX film can achieve efficient non-contact radiative cooling.

Portable optical power meter is one of the most common test equipment in the field of optical fiber communication, especially widely used in optical fiber construction. Because they are often used outdoors, such instruments need to meet the key characteristics of low power consumption, high measurement accuracy and portability. At present, there is a big gap between domestic portable optical power meters and foreign ones. In view of this situation, this paper proposes a low-cost, portable intelligent embedded optical power meter system, which supports intelligent calibration. The software adopts the method of thread concurrency to improve the operation efficiency, accelerate the response time, and process the data with appropriate algorithms. It can meet the needs of on-site construction detection and diagnosis of optical fiber communication engineering, and has a broad application market.

The theory analysis of the interference fringe for the dual beam system is currently based on the ordinary Gaussian beam model where the velocity measured by dual beam LDV is v =λ f_d/ (2sinα₀ ) . α_o is the half intersection angle between two intersecting laser beams. And the direction of the velocity is along the normal of the bisector of the optical axis of two output beams ( y axis) after focused by the positive lens. This study establishes two interference fringe models for the dual beam LDV based on the ordinary Gaussian beam and off-axis Gaussian beam model, respectively. In Model one and Model two, the velocity of the particles running through the measurement volume is v _model1 = λf_d/(sinα₁+ sinα₂ and V _model2 = λf_d/(2tanα₀) , respectively, where α1 is the angle between optical axis of one output beam and the positive lens, and α2 is the angle between optical axis of other output beam and the positive lens. Two models indicate that when the distances between the optical axis of two input parallel beams and the positive lens is not equal, there is an angle between the distributing direction of the interference fringe and y axis.

This paper addresses the significance of phase unwrapping algorithms in optical measurements. It explores an improved rhombus phase unwrapping algorithm based on a temporal multiplexing mechanism of phase-shifted fringe patterns. The algorithm aims to enhance the accuracy and stability of relative phase unwrapping. Firstly, the temporal multiplexing technique using phase-shifted fringe patterns is employed to acquire wrapped phase information from different sequences, thereby increasing the availability of phase information. Subsequently, the improved rhombus phase unwrapping algorithm is applied using the multiplexed templates, utilizing the phase differences between adjacent pixels for phase unwrapping. During the algorithmic process, the classification strategy for independent pixels introduced by temporal multiplexing enhances the robustness and computational efficiency of the algorithm. Experimental results demonstrate that the improved rhombus phase unwrapping algorithm under the temporal multiplexing mechanism effectively restores the phase information of the measured object and exhibits strong anti-interference capabilities in complex backgrounds. This research provides a novel solution for the application of phase unwrapping algorithms in the field of optical measurements.

The sun is the source of phenomena in the solar terrestrial space environment, and ground-based solar observations have important scientific and educational value. The optical telescope is an effective observation equipment. This article introduces the construction ideas and methods of an optical telescope teaching experimental system, which has three functions: star searching and guidance, sun observation, and night sky photography. In response to the teaching needs of the course, 11 experiments were conducted, including observations of the solar sphere and chromosphere, imaging observations of the moon, observations of major planets (Saturn, Jupiter, or Mars) and imaging observations of galaxies, effectively improving the practical teaching effectiveness of the course.

Microarray chip with micro-nano composite structure consists of an array of micropost structures and nanorods covering the top of the posts. This structure can significantly enhance the signal-to-noise ratio and improve the cross-infection problem to increase the detection sensitivity and accuracy. However, the construction of such structures is still limited to the laboratory research stage, which is mainly realized by UV nanoimprinting and glancing angle deposition methods, and the preparation process is complicated, time-consuming, and inefficient, which greatly restricts the wide application of highly sensitive microarray chips. Therefore, to achieve high accuracy and sensitivity in the large-scale, high-efficiency production of microarray chips, a micropost array structure was fabricated via injection molding. The top of the micropost structure (spotting area) was selectively deposited with Ag nanorods using glancing angle deposition, forming a micro-nano composite structure substrate. Despite a 4 μm discrepancy between the height of the micropost structure on the microarray chip (54 μm) and its designed height (58 μm), the deviation was within acceptable limits. While the uniformity of Cy-3 fluorescence signal across the micro-nano composite structure substrate (with an average signal value of 12519.0 and a coefficient of variation of 4.79%) was slightly lower than that of the UV nanoimprinting chip (with an average signal value of 12495.8 and a coefficient of variation of 1.35%), both exhibited similar fluorescence signal enhancement characteristics. Therefore, this method can serve as a reference for the high-throughput, efficient production of microarray chips.

Laser-induced fluorescence spectroscopy plays an important role in rapid detection and identification of oil spills at sea. The fluorescence spectra of different thicknesses of oil films of the same type of oil are very similar, which makes it difficult for the method to detect and recognize the thickness of oil films. In this paper, a laser-induced fluorescence detection method based on convolutional neural network algorithm is proposed to measure the thickness of oil films. Experimental studies of laser-induced fluorescence were conducted for different oil spill film thicknesses, and fluorescence spectral data were obtained for oil-free water and for 10 different oil film thicknesses. The recognition of 11 samples with different oil film thicknesses was realized by Matlab software using convolutional neural network algorithm. It was verified that the method can completely recognize different thicknesses of oil film with high accuracy and low training set error. Based on the convolutional neural network algorithm, the oil spill volume can be calculated by detecting the oil spill thickness, which has certain application value for the protection of marine environment.

Data from soft X-ray telescope can provide the basis for revealing some extreme physical laws and phenomenon. So, X-ray telescope is a kind of important equipment for space science observation. Soft X-ray optical system is the core component of X-ray telescope system, and according to its influence on X-ray, the optical system is divided into three categorys: collimating type, focusing type and modulating type. By introducing the working principle, performance characteristics, preparation technology and application status of the three optical system at home and abroad.The three important development trends about the space X-ray detection load technology is made: optical system miniaturization and lightweight; easily of array integration; multi-dimensional information of X ray photon is extracted. This analysis will give powerful guide for design of the soft X-ray optical detector in the future.

As the demand for data centers and high performance computing continues to grow, the need for high-speed and high-efficiency data transmission technology is also on the rise, and PAM4 technology has become one of the key technologies to realize high-speed data transmission due to its advantages in increasing channel capacity. In this paper, an SFP56 packaged optical module based on PAM4 modulation is designed, and the optical module realizes short-distance transmission at 64 Gbps through a DSP chip. The purpose of this module design is to improve the bandwidth density and energy efficiency of the interconnections within a data center. The design of this paper utilizes the advanced PAM4 signal processing algorithm to improve the transmission rate of the module. In addition, this paper utilizes the FEC technique to reduce the BER and further improve the transmission quality and reliability. At the same time, COB technology is used for packaging to reduce the cost of individual modules, and VCSEL lasers are used to achieve optical signal transmission in multimode fiber to further reduce the cost of individual modules.

Machine vision angular displacement sensors have the characteristics of high precision and high reliability, gradually becoming a new technological development direction for angular displacement sensors. The optical system is one of the key components for machine vision angular displacement sensors to achieve high-precision measurement. This article presents an optical system design for a machine vision based angular displacement sensor. The optical system consists of two lenses, with a total optical length of only 8.9mm. The 80% geometric encircled radius is less than 14.1um, and the maximum distortion value is 1.6um. It has the characteristics of miniaturization and high image quality. The processing and assembly of the optical system have been completed, and the optical system has been tested on an angular displacement sensor prototype. Through analysis of the measured image data, the value of the encoded stripe edge in the image is approximately 16.5um, which is basically consistent with the design value. The imaging performance of the designed optical system was tested through experiments, and the correctness of the design theory and results was verified.

This research introduces an advanced remote multicolour excitation laser-induced fluorescence (LIF) imaging technique, utilizing a mobile lidar system equipped with a frequency-tripled Nd:YAG laser and optical parametric oscillator. Operating across UV to near-infrared wavelengths, this method significantly enhances non-destructive material surface analysis. The system's efficacy is validated in varied settings, including laboratories and outdoor environments like stadiums and cultural heritage sites, effectively distinguishing material properties at distances up to 60 meters. The study emphasizes the integration of multiple excitation wavelengths to capture diverse fluorescence characteristics, improving material heterogeneity detection. Utilizing correlation analysis, the method compares fluorescence spectra against reference spectra to ascertain material composition with high precision. Key to this research is the LIF system's ability to differentiate materials without physical contact, exemplified by the analysis of antique bricks. This capability, along with the system's stability in spectral data acquisition, synthesis of composite spectra from varied wavelengths, and efficient data processing, positions this technology as a potent tool in cultural heritage preservation and a precursor to future advancements in remote sensing and diagnostic imaging.

This paper refers to the technical requirements of gravitational wave telescopes and focuses on the design and alignment of the telescope's primary and secondary mirror system. Parameters for the reflective telescope's primary and secondary mirror system are determined based on the design requirements. The materials for the mirror system structure are chosen by analyzing stiffness ratio, thermal expansion coefficient, and surface roughness. The deformation and stress of the support structure under gravitational conditions are analyzed, and its rationality is verified through temperature simulation. Before the alignment, a sensitivity matrix for system aberrations is obtained by introducing maladjustments in different degrees of freedom to guide the alignment. Using the autocollimation method and flat mirror interferometer for system testing, the results show a wavefront error RMS of RMS=0.0316 λ and PV=0.318 λ (λ=632mm). The test results indicate that the primary and secondary mirror system structure meets the initial design requirements.

The nonlinear errors of Position Sensitive Detectors (PSD) will cause the less tracking accuracy of the laser trackers. To address the issue, in this paper we proposed a nonlinear compensation method, combining Sparrow Search Algorithm (SSA) with BP neural network. The SSA was employed to find optimal initial thresholds and weights of the BP neural network. An SSA-BP neural network model was created and tested using 443 sets of experimental data. The experimental results show that this method reduces the peak error of the BP neural network by over 7 times and lowers the average error by more than 2 times, significantly enhancing the measurement accuracy of the detector.

In this paper, the electronic properties and optical absorption characteristics of Indium arsenide (InAs) nanowires with different defects, including antisite defects, vacancy defects, and interstitial defects, at various locations such as the core layer, subsurface, and surface, were investigated using first-principles calculations. The results indicate that InAs nanowires with defects create new impurity energy levels in the energy band structure, with In_As, As_i, and V_In acting as acceptors and As_In, In_i, and V_As acting as donors, rendering the InAs nanowires p-type or n-type. Furthermore, defects disrupt the absorption properties of the nanowires at the peak of the absorption spectrum in the ultraviolet region, whereas defects positively affect the light absorption of InAs nanowires in the visible and infrared light regions. In particular, it is in the infrared light region that the redshift of the V_In defect model is most pronounced and enhances the infrared absorption of InAs nanowires.

Orbital angular momentum (OAM) is implemented as an independent information channel in multiplexed holography. Vortex beams carrying OAM are characterized by helical wavefront. By theoretically infinite orthogonal modes, OAM can be used as an additional degree of freedom (DOF) to increase the information capacity of holography. However, the helical phase pattern can be encoded into only one hologram, that is, a topological charge (TC) channel can be associated with only one target image, which limits the multiplexing capability of OAM holography. In this paper, elliptic perfect optical vortex multiplexed holography with fractional-order TC is proposed. The modulated parameters of FEPOV, namely TC, ellipticity, and gap number, can be used as independent DOFs to encode and decode holograms. Using these three parameters as encryption keys, single-parameter and multi-parameter encrypted holograms are designed to enhance information capacity and security. The method demonstrates great potential in the field of information storage and encryption.

When heterodyne interferometers employ the traditional successive phase unwrapping algorithm (SPUA) for implementing online low-frequency vibration measurements, challenges posed by extensive data volume and time-consuming data processing typically arise. To address these challenges, this paper introduces an undersampling phase unwrapping algorithm (UPUA) based on Kalman motion estimation for heterodyne interferometers. Specifically, the UPUA utilizes the six preceding phases to estimate the phase jerk at the next sampling moment. Furthermore, the sampling frequency for the next sampling moment, denoted as fs, is determined utilizing the peak jerk of the phase. Subsequently, the three preceding phases and fs are employed to derive the estimated phase at the next sampling moment. Following this, the SPUA is further utilized to determine the measurement phase at the next sampling moment after setting the sampling frequency to fs. Ultimately, the actual phase is determined by combining the measured phase with the estimated phase, thus achieving online undersampling phase unwrapping. Simulation and experimental results demonstrate that UPUA adaptively adjusts the sampling frequency and significantly reduces the data volume compared with SPUA in the case of low-frequency vibration measurements.

Since the Young's formula for spherical waves can’t accurately describe the field curvature and astigmatism of Gaussian beams, this study derived a Young's formula suitable for the off-axis transmission of Gaussian beams, which aids in the calculation of field curvature and astigmatism of Gaussian beams. Through five sets of experiments, the accuracy of the formula was verified, revealing that the size of the incident beam waist, the position of the beam waist, and the beam quality factor M² are all key factors affecting the field curvature and astigmatism of Gaussian beams.

Compound eyes are widely found in insects and other invertebrates, serving as their primary visual organs. The unique structure and function of compound eyes have long captivated the attention of scientists. Taking dragonflies as an example, their exceptional reaction speed and remarkable observation ability can be attributed to the presence of large compound eyes on their heads. In this study, we examined the characteristics and functions of dragonfly compound eyes by observing the diffraction phenomenon on temporary slides, aiming to explore the potential applications of bionics in replicating these features. Our findings revealed that dragonfly compound eyes possess distinctive optical properties including multi-channel imaging, wide-angle field of view, and exceptionally high temporal resolution. Moreover, the neuronal network within these compound eyes enables simultaneous sensing and tracking motions from multiple directions while rapidly and accurately processing optical signals. Therefore, drawing inspiration from both its optical properties and information processing capabilities, we can derive novel ideas for developing artificial compound eyes.

In this paper, a method of detecting the central wavelength of ultra-weak chirped fiber Bragg grating is proposed, based on correlation coefficient to solve the problem of calculating the central wavelength, in the case of wideband reflection spectrum jitter. A mathematical model of the jitter spectrum of grating with piecewise step function superimposed by Gaussian noise is built. By moving the relative positions, the curve of their correlation coefficients is obtained, and the horizontal coordinate corresponding to the maximum correlation coefficient is found, to determine the central wavelength it. Then, the variation trajectories of the correlation coefficient between the odd function and the original signal at different relative positions by simulation are analyzed. Further, a variety of algorithms are used to compare and analyze the calculation results of the central wavelength of a single grating with spectral bandwidth greater than 3 nm and reflectance less than -30 dB. Finally, the ultra-weak chirped fiber Bragg grating array with 284 base cables is compared and analyzed, and the results show that the calculated range of the central wavelength is 0.17 nm. The variance of 0.05 proves that the proposed algorithm is simpler and more robust. This method has potential significance for calibration and engineering application of ultra-weak chirped fiber Bragg grating arrays.

The laser doppler blood flow measurement technology achieves the measurement of blood flow and velocity by using laser irradiation on moving red blood cells within the human body, generating doppler frequency shifts. Compared to other blood flow measurement techniques, its output signals exhibit a strong linear relationship with blood flow, allowing for a more accurate reflection of changes in blood flow. This technology provides a convenient, user-friendly, non-invasive optical detection method for various applications, including clinical surgical assistance, blood perfusion monitoring, drug efficacy assessment, and pathological research. Ensuring the accuracy of blood perfusion measurements and the depth of tissue measurements, especially under dynamic conditions, is a key technology in the research and application of laser doppler blood flow measurement devices. This review introduces the working principles of laser doppler blood flow measurement technology, outlines the research progress of this technology and related devices in various clinical application areas, analyzes key issues influencing the accuracy of its clinical applications and the research progress of relevant technologies. It also provides prospects for the future development of this technology and its devices, offering valuable insights for the research and development of wearable microcirculation measurement devices.

Applying the image deconvolution algorithm to Brillouin optical time domain reflectometer (BOTDR) can enhance the spatial resolution. In this paper, the blurring effect of point spread function on Brillouin frequency shift of sensing fiber under different pump pulses is numerically simulated based on the two-dimensional convolution theory of BOTDR. The recovery effects of several classical image deconvolution techniques, including Wiener filtering, regularized filtering, Richardson- Lucy method and blind deconvolution, in improving the spatial resolution of BOTDR are experimentally compared. The experimental results show that all four filtering methods can improve the spatial resolution from 2.5 m to 20 cm. In this application, the Wiener filtering, regularized filtering, and the Richardson- Lucy method provide almost the same restoration, while the blind deconvolution method provides a poorer restoration.

Evolution of the model basing on the nonlocal response functions has been accessed according to the (2+1)d schrödinger equation in cartesian coordinates .this paper presents the singular laguerre-gaussian beams modulated by the airy functions in free space. It is possible to solve process the space-time multiple beams propagating in the medium using the superposition principle. Even more, it provides the theoretical basis for all-optical control technology.

The calibration method based on correlated photons can realize absolute calibration without standard transfer. The solar spectral irradiance meter using this calibration method needs a correlated photon source with a broad spectrum to achieve absolute calibration in the solar reflection band. In the early stage, non-collinear phase matching combined with multiple crystals was generally adopted to achieve wide spectral coverage. In this paper, a continuous wide spectral correlated photon source is obtained using pumping a BBO crystal by a 532nm laser and continuous angle tuning collinear phase matching. The collinear phase matching positions at different wavelengths are determined by the rotation crystal which shrinks the relevant photon rings into circular spots. The spectral range and correlation of the broad spectral correlated photon source are verified by the correlated photon ring image and the coincidence counting of four pairs of correlated photons of 800nm/1580nm, 840nm/1450nm, 900 nm/ 1300nm, and 950nm/1200nm.

Aiming at the structural asymmetry problem caused by the inconsistency of the two optical fibers connecting the Y waveguide and the resonant cavity in the RFOG optical system driven by a broad-spectrum light source, a study on the non-reciprocity of the optical structure of the RFOG driven by a broad-spectrum light source was carried out. A model of the optical system structure non-reciprocity is established, and the effect of the optical system structure non-reciprocity on the gyroscope system in a variable temperature environment is analyzed. The results show that the optical system structure non-reciprocity causes the gyro sweep mode curve to change, but does not affect the system accuracy when there is no temperature change, and the temperature characteristics of the optical system structure non-reciprocity lead to pseudo-rotational speed output of the gyro output in a variable temperature environment, which is strongly correlated with the length difference and the rate of change of temperature.

The method for achieving non-collinear phase matching in stimulated polariton scattering (SPS) using cross-pumping is proposed. Under sub-nanosecond pulse laser pumping conditions, tunable narrowband Stokes light output is obtained. The cross-pumping configuration is established by total internal reflection of the pump light on the side of the crystal. By rotating the crystal, altering the total internal reflection angle of the pump light, thereby changing the phase matching condition and tuning the frequency of the output Stokes light. The output Stokes light is with a linewidth of 0.2 nm. The wavelength tuning range is 1068 nm to 1075 nm. At a pump energy of 8 mJ, the output energy is 1.1 mJ, corresponding to a conversion efficiency of 13.8%. This study provides a reference for phase matching methods in nonlinear parametric conversion processes.

Micro-LED has been widely studied due to its strong performance and has applications in fields such as display, biology, and communication. However, as the size of the micro-LED decreases, so does the light extraction efficiency and top emission, which affects its development and application. The improvement of light extraction efficiency is crucial. Surface nanostructures and chip design are utilized to enhance the top emission efficiency of micro-LEDs in this work. Top emission percentage and top emission efficiency of 10 μm GaN-based vertically flip-chip micro-LED are studied in relation to their structural parameters using the three-dimensional time-domain finite-difference method (3D FDTD) simulation. The results show a clear relationship between the structural parameters and the top emission efficiency. Surface micro-LED structures with a period ranging from 0 to 1200 nm are designed and prepared. The sidewall inclination is also optimized to achieve the optimal top emission efficiency. Full-structure simulations of spectral distributions and dipole source polarization are performed to obtain accurate results. The top emission percentage and top light emission efficiency are improved from 22.0% and 6.5% to 78.0% and 26.5%, respectively, compared to the conventional 10 μm micro-LED structures.

A deep understanding of the spatiotemporal distribution characteristics of material molecules, emitted from nanopores, near the top surface of nanoporous thin films has practical application value for the preparing biomedical optical sensing films and nano-photonic sensors, delivering and screening of drug molecules, and so on. In this study, the direct simulation Monte Carlo method as employed to investigate the velocity and amount distribution pattern of particles emitted from a nanopore (multi-nanopores) with 80 nm diameter and 1 μm depth at various initial temperatures (T=300 K, 400 K, and 500 K) near the top surface of a nanoporous structure film. Especially, the variation of particle number, temperature, and pressure over time in the regions of 500 nm and 1000 nm were analyzed, as well as the variation of temperature and pressure along the nanopore axis with the variation of Knudsen number. Additionally, the impact of more pores on particle number and temperature distribution over space and time was analyzed. The simulation results show a symmetric distribution of particle numbers, with lower temperatures in the axial region compared to the initial temperature, significant temperature changes on both sides, and a continuous decrease in pressure. The along-travel temperature reaches its maximum value at a distance of 4 μm from the center of the nanopore, with a subsequent decrease in temperature as the Knudsen number increases. These research results have new inspirations for gas sensing and enhancing optical sensing with nanoporous thin films, as well as designing functional optic material with micro-/nano- structures.

Laser scanning technology is gradually being used in tunnel 3d modeling and deformation monitoring to assist in tunnel construction and operation and maintenance management. After laser scanning tunnels, point cloud denoising is an important part of point cloud processing. Nevertheless, current statistical-based point cloud denoising algorithms can cause some point cloud information loss, resulting in voids or distortions in the tunnel monitoring area. In this paper, the characteristics of point cloud noise are revealed by analyzing the plane data set obtained from the experiment. And according to the point cloud noise characteristics, a new point cloud denoising algorithm is proposed from the perspective of point cloud noise generation rather than a statistical calculation method. It is found that point cloud noise is mainly caused by the ranging error along the laser incidence direction. The point cloud corresponds to a more consistent performance of the laser incidence angle, which has less influence on the point cloud noise. The point cloud denoising reduces the ranging error along the laser incidence direction. This denoising algorithm, derived from the principle of point cloud noise generation instead of the conventional statistical noise reduction method, provides a noise reduction perspective for point cloud noise reduction. Furthermore, this denoising algorithm substitutes the original sampling point with a point located on its laser ray. This point is specifically identified as the intersection of the laser ray of the sampling point and the plane fitted with its neighboring points. This algorithm employs the newly sampled point in place of the original point cloud, thereby preserving the information within the point cloud. It is also capable of executing multiple noise reduction procedures on the point cloud, with the most significant effects observed in the first three iterations. This method is particularly appropriate for measurements that demand high sensitivity to original data, such as tunnel deformation monitoring and heritage detection.