A spiking photonic reservoir computing system based on photonic spiking neuron is proposed in this paper. This system utilizes the high nonlinearity and excitation characteristics of selected photonic spiking neuron to perform nonlinear classification task. It has been proved that the proposed spiking reservoir can well perform nonlinear classification task. Furthermore, our research also study the effect of different input dimensions and output processing methods on the system. The system can still have good performance under a low input dimension. The results show that the proposed system has strong learning ability and can be used to implement more machine learning tasks.
Plasmonic devices are considered as a potential platform to realize highly integrated photonic circuits. Optical logic gates are fundamental computing and light-controlling elements in optical circuits and optical computing, and many plasmonic logic gates have been studied. However, these devices can only realize single or several specific logical operations. In this work, we propose a multiport plasmonic system to realize all-logical processing based on coding metamaterials (CMs) and inverse design. We utilize nondominated sorting genetic algorithm-II to optimize the distributions of CMs. After optimization, the simulation results exhibit that all types of logic gates (AND, OR, NOT, NAND, NOR, XOR and XNOR) can be obtained with the operating wavelength of 1.31μm and a small footprint (0.8×1.1 μm2). Moreover, the extinction ratio between logical "1" and "0" states exceeds 20 dB for OR, NOT, XNOR and XOR logic gates.
In this paper, we design a near-infrared 3D multifunctional metamaterial (3MM) to achieve several different functions based on modified direct binary search (DBS) algorithm. In order to demonstrate the versatility of 3MM, an optical absorber is obtained based on the inverse design technology. Besides, we also utilize it to achieve plasmon induced transparency (PIT) like effect. Finally, to prove the advantages of 3MM, we have designed the corresponding 2D metamaterial to realize the same functions based on the DBS algorithm for comparison. The comparison results show that the performance of 3MM is much better than the 2D metamaterial. Compared with previous works, our proposed 3MM not only demonstrates the advantages of 3D metamaterials in manipulating the absorption spectrums and PIT-like effects but also provides a general framework for other spectrum-related functions in various field, such as imaging, sensor, chemical analysis and so on.
Conventional silicon optical waveguide can be effectively coupled to plasmonic waveguide, but there is no structure of comparable coupling efficiency, wide optical bandwidth and polarization independence to convert light from silicon waveguide to metal-dielectric-metal (MDM) waveguide. In this paper, we investigate a novel mode converter based on the embedded coding metamaterials to effectively convert the TE/TM mode in a silicon waveguide to the SPPs mode. We use some optimization methods (genetic algorithm, particle swarm optimization, multi-traversal direct-binary search and simulated annealing) in the design of coding metamaterials to improve the performance metrics. In order to obtain better results, we change the value of different parameters under the control of a single variable to study its influence on the structure of the design. The simulation results have been demonstrated numerically that high transmission efficiency is up to 93% and the bandwidth can cover from 1450 nm to 1650 nm, the converter can perform polarization-invariant conversion as well. Compared with the previous researches, we not only propose a high-performance mode converter but also introduce an efficient algorithm for the inverse design of coding metamaterials.
Single and double plasmon induced absorption (PIA) effects have been numerically achieved in a metal-insulator-metal (MIM) waveguides end-coupled with resonators structure. Here, the structure composed of two MIM waveguides and three side-coupled rectangular resonators is proposed to generate double PIA effects. A multimode coupling mechanism derived from the coupled mode theory is established to describe the spectral features, which is greatly agree with the simulation results, may provide a guideline for designing and analyzing the integrated plasmonic devices based on the multiple PIA effects. What’s more, dynamical control of the amplitude and bandwidth of the multiple PIA effects can be achieved by means of filling poly (methy1 methacrylate) or Kerr material in the Fabry-Perot resonators. Compared with previous reports, the multiple PIA effects are analyzed theoretically in a plasmonic waveguides end-coupled with resonators structure, will have practical applications in plasmonic filters, modulators, sensors, switches and fast light in highly integrated plasmonic circuits.
In this article, we propose a novel method using machine learning, especially for artificial neural networks (ANNs) to achieve variability analysis and performance optimization of the plasmonic refractive index sensor (RIS). A Fano resonance (FR) based RIS which consisted of two plasmonic waveguides end-coupled to each other by an asymmetrical square resonator is taken as an illustration to demonstrate the effectiveness of the ANNs. The results reveal that the ANNs can be used in fast and accurate variability analysis because the predicted transmission spectrums and transmittances generated by ANNs are approximate to the actual simulated results. In addition, the ANNs can effectively solve the performance optimization and inverse design problems for the RIS by predicting the structure parameters for RIS accurately. Obviously, our proposed method has potential applications in optical sensing, device design, optical interconnects and so on.
We report an optical vector network analysis (OVNA) based on optical suppressed carrier double-sideband (DSB) modulation and the Pound Drever Hall (PDH) technique. In this novel scheme, the optical carrier suppressed DSB modulation signal propagates through the high Q optical device, and then the double frequency of the driven radio frequency signal is detected, by which the frequency responses of the device can be accurately achieved. Comparing with the common DSB-based OVNA, by biasing the modulator at the minimum transmission point (MITP), the accuracy improvement can be realized since the errors caused by the even-order sidebands are eliminated. Moreover, the high stability of the proposed OVNA can also be achieved by using the PDH technique. In the proof-of-concept experiment, the magnitude and phase responses of the Fabry-Perot (FP) interferometer are realized with high accuracy when the modulation index is small. There is no repeated frequency response even if the test time is up to 30 minutes. The proposed scheme provides a novel strategy for high-accuracy frequency responses measurement, which can be potentially used in high Q optical devices characterization.
A digital signal processing (DSP) scheme based on Volterra equalizer (VE) combined with adaptive noise-whitening post-filter and maximum likelihood sequence detection (MLSD) is proposed to mitigate nonlinear impairments in vertical-cavity surface-emitting lasers (VCSEL) multimode fiber (MMF) system. Successfully transmission of 108 Gb/s, 100 Gb/s and 60 Gb/s 4-ary pulse amplitude modulation (PAM4) signal over 5 m, 160 m and 460 m OM3-MMF is demonstrated below the 7% overhead hard-decision forward error correction (HD-FEC) bit error rate (BER) threshold by using a 20-GHz class VCSEL at 850 nm. Linear pre-equalization is applied to mitigate severe bandwidth limitation of the system. Our experimental results show that the scheme can well mitigate modulation nonlinearity induced by VCSEL and fiber nonlinearity induced by MMF. The BER decreases about two order of magnitude compared to linear equalizer after 100 m OM3-MMF transmission for 100 Gb/s PAM4 signal.
We have experimentally demonstrated a direct-detection (DD) 112-Gbit/s 16 quadrature amplitude modulation (QAM) transmission over single-span 140-km standard single mode fiber (SSMF) with Kramers-Kronig receiver and a sparse I/Q Volterra filter (VF). The sparse I/Q VF was proposed in our previous work and it is based on dual-input real-valued Volterra series and ℓ1-regularization method. In this paper it is used for compensating the nonlinear distortion in a short-reach DD optical 16-QAM signal transmission system. In back to back case, sparse I/Q VF represents the great compensation ability to the saturation effect of the electrical amplifiers and the nonlinear sinusoidal transfer function of I/Q modulator. It provides around 1-order magnitude improvement of BER when reducing 84% complexity from full I/Q VF. For fiber transmission case, sparse I/Q VF can mitigate the fiber nonlinearity effectively and it achieves single-span 140-km transmission at hard-decision forward error correction (HD-FEC) threshold of 3.8 ×10-3 with less than half complexity of full I/Q VF. Besides, optical signal noise ratio (OSNR) performance at 120 km is measured and sparse I/Q VF reduces the required OSNR at HD-FEC threshold by 1.3 dB. In a word, we investigate the performance of sparse I/Q VF in short-reach optical 16-QAM transmission system and sparse I/Q VF reveals its potential in the growing short-reach applications, such as data center inter-connection and metropolitan area network.
A novel scheme for the generation and stabilization of the millimeter-wave (mmW) signal is theoretically analyzed and experimentally demonstrated. By using the microwave photonics frequency-quadrupling technology and phase-locked optoelectronic oscillator, we generate the millimeter-wave signal with low phase noise and high stability without the frequency limitation of the electrical phase detector and the voltage-controlled microwave phase shifter. Finally, a 40-GHz mmW signal with the stability of 1.38 × 10−12 at the average time of 100 s is generated. The spurious suppression ratio reaches 97 dB, and the measured single-sideband phase noise is lower than -103 dBc/Hz at 10-kHz offset frequency.
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