2022
2022
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Record 169 of
Title:Ultrafast dynamic RF-spectrum investigation of soliton microcombs
Author(s):Hu, Hao(1); Wang, Ruolan(1); Wang, Weiqiang(2,3); Chen, Liao(1); Zhao, Yanjing(1); Wang, Xinyu(2,3); Zhang, Chi(1,4); Zhang, Wenfu(2,3); Zhang, Xinliang(1,4)Source: APL Photonics Volume: 7 Issue: 4 DOI: 10.1063/5.0084279 Published: April 1, 2022Abstract:Dissipative Kerr solitons in microcavity systems exhibit remarkable nonlinear dynamics. The real-time measurement of soliton motion facilitates the comprehensive understanding of soliton physics. In this Letter, an all-optical radio frequency (RF) spectrum analyzer (named f-LISA) is used to characterize various stable soliton states and to track relative soliton motion in real time. By applying an inverse Fourier transform to the broadband RF spectrum, the autocorrelation traces are obtained with a temporal resolution of 373 fs and an ultrahigh frame rate of 20.6 MHz. We successfully characterize not only the stable single soliton state but also the stable multi-soliton states with different azimuthal angles between adjacent solitons. Furthermore, the dynamics of soliton switching from four-soliton state to single soliton state is observed in a temporal window of 60 μs. It is believed that the proposed scheme provides an alternative way to visualize the multi-soliton trajectories and enable the study of the soliton dynamics in integrated microcavities. ? 2022 Author(s).Accession Number: 20221712010201 -
Record 170 of
Title:Low Noise Driver And Bias Hardware Circuit Degisn Based On CMOS Detector
Author(s):Shen, Chao(1,2); Ma, Caiwen(1); Gao, Wei(1); Song, Zongxi(1); Wang, Fengtao(1); Li, Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12169 Issue: DOI: 10.1117/12.2627221 Published: 2022Abstract:Compared with CCD detector, CMOS detector has the advantages of high integration, low power consumption, fast readout speed and low production cost. CCD detectors are used in traditional astronomical observations. At present, low-noise CMOS detectors are not used to realize spaceborne astronomical projects in the world. From the index analysis of a project, one 6K * 6K CMOS detector which developed by a company can meet application of one project?Based on this detector, designing low noise driver and bias hardware circuit. This design mainly uses LDO with low noise and high PSRR to produce stable low noise driving power supply,in addition, the driving signal waveform required by the detector is controlled by FPGA to ensure the signal integrity to avoid interference feed?The bias voltage required by the detector is generated by low-noise voltage reference device, high-resolution DAC and low-noise operational amplifier. ? 2022 SPIEAccession Number: 20221611967674 -
Record 171 of
Title:Stimulated Raman scattering induced dark pulse and microcomb generation in the mid-infrared
Author(s):Liu, Mulong(1); Huang, Huimin(2); Lu, Zhizhou(3); Zhou, Wenquan(1); Wang, Yuanyuan(1); Cai, Yanan(1); Zhao, Wei(4)Source: New Journal of Physics Volume: 24 Issue: 5 DOI: 10.1088/1367-2630/ac6530 Published: May 1, 2022Abstract:We demonstrate that strong stimulated Raman scattering in silicon and germanium microresonators can induce stable and breathing dark pulses generation circumventing traditional complex approaches such as pump modulation and mode coupling. Although multi-photon absorption shows a small influence on the detuning value for stable dark pulse excitation, the concomitant free carrier will assist dark pulse excitation and broaden the excitation area of dark pulse thus making it easier to capture stable pulse. Furthermore, dark breather dynamics in Si and Ge are also observed, which shows distinct properties from the dark soliton breathers dominated solely by Kerr effect. Finally, we show that octave spanning mid-infrared (MIR) microcomb can be generated combining with high-order dispersion engineering, which in turn affects the breathing dynamics of dark pulses. Our findings provide another way for the initiation of dark pulses in group IV materials and broadband MIR microcomb generation for spectroscopy applications. ? 2022 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaft.Accession Number: 20222112133011 -
Record 172 of
Title:An Improved Small Target Detection Algorithm for SSD
Author(s):Ai, Han(1,2); Zhang, Haifeng(1); Ren, Long(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12331 Issue: DOI: 10.1117/12.2652290 Published: 2022Abstract:In order to improve the accuracy and robustness of the small target detection for SSD (Single Shot Multi-Box Detector) algorithm, this paper proposes an improved SSD algorithm. Firstly, the Mish activation function is introduced in the backbone network to provide more linear relationships. Secondly, a copy-reduce-paste data enhancement method is proposed to ensure a more balanced train. In the multi-scale detection stage, feature enhancement module and feature fusion strategy guided by channel attention mechanism are used to improve the feature information. At the same time, modify the loss function to improve the model training effect. Experiments on the VOC2007+2012 dataset show that the detection performance of the proposed algorithm is better than that of the SSD algorithm. ? 2022 SPIE.Accession Number: 20224813166745 -
Record 173 of
Title:High-Precision Registration Algorithm of Variable Scale Heterogeneous Point Clouds Based on Intrinsic Shape Signatures Features
Author(s):Liu, Chang(1); Zhang, Gaopeng(2); Du, Hubing(1); Lu, Rong(2); Zhao, Jingwei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12478 Issue: DOI: 10.1117/12.2654872 Published: 2022Abstract:Many space tasks, such as on-orbit servicing, space rendezvous and docking strongly rely on accurate relative position and posture collectively (referred to as pose) of spacecraft. The single measurement methods are limited to their respective advantages and disadvantages, which cannot meet the demand of non-cooperative target pose measurement in complex space situations. But due to different information sources, multi-source heterogeneous point cloud registration algorithms face problems such as noise impact, outliers, partial overlap of point clouds, difference in density of point clouds, inconsistent scales and so on. To solve this problem, based on the Scaling Iterative Closest Point (SICP) algorithm, this paper proposes a high-precision registration algorithm of variable scale heterogeneous point clouds based on intrinsic shape signatures (ISS) features. Firstly, the algorithm down samples the voxels of the point cloud to be aligned, sparseness the number of point clouds, and screens out some noise; Secondly, coarse alignment of the feature point clouds extracted by the ISS algorithm is performed by establishing a cost function containing the surface variance of the feature points and the module value of the Euclidean distance of the feature points from their centers of mass; Finally, the two-point clouds are finely aligned by the SICP algorithm. The experimental results show that the algorithm shows high robustness and well real-time performance, and can realize the accurate registration of multi-source heterogeneous point clouds with multi scales. ? 2022 SPIE.Accession Number: 20230413445478 -
Record 174 of
Title:Image noise recognition algorithm based on data enhancement
Author(s):Guan, Lei(1,2); Huang, Jijiang(1); Wang, Hao(1); Chen, Weining(1); Lu, Rong(1,2); Chen, Zhiqiang(1,2)Source: ACM International Conference Proceeding Series Volume: Issue: DOI: 10.1145/3584376.3584547 Published: December 16, 2022Abstract:Image denoising has always been an indispensable part of image processing tasks, and the quality of image preprocessing algorithms is directly related to the effect of subsequent image processing. Most existing denoising algorithms explicitly define the type and distribution of noise, for example, the artificially set additive Gaussian white noise which is based on prior knowledge. But on the one hand, the actual real image noise is not equivalent to Gaussian noise. The noise distribution of different noise types such as Gaussian, Salt and pepper noise, Rayleigh, Uniform noise is very different. It is not possible to generalize in the process of image denoising. On the other hand, images in real scenarios often have problems such as unrepeatable acquisition, lack of data information, or even only single image information, which can't support large-scale deep learning and discrimination. The above two points limit the application of most algorithms in real scenarios. In this paper, a new real image noise recognition algorithm is proposed. Aiming at the problem of single noise image and lack of prior knowledge in real scenes, the noise distribution is first learned and the image enhancement dataset is generated through dual-channel simulation in traditional and deep learning to solve the problem of lack of real image data. Then, the noise is identified by the deep learning pre-Trained model, and the noise type that most closely matches the noise distribution of the real image is found. Thus, the influence of prior knowledge of image noise on the denoising process is freed for the subsequent denoising task. Experimental results show that our algorithm framework is not limited by the size of real images and datasets, and does not require prior knowledge of real scenes. The algorithm has good recognition accuracy for different types of image noise, and good robustness for images of various scenes, which provides data support and accuracy guarantee for a series of tasks such as subsequent denoising, classification, recognition, and tracking of computer vision. ? 2022 ACM.Accession Number: 20231914063898 -
Record 175 of
Title:Imaging through scattering medium based on lensless Fourier transform digital holography
Author(s):Zhang, Hui(1,2); Wang, Ruiduo(1); Zhang, Zaikun(1,2); He, Zhengquan(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12166 Issue: DOI: 10.1117/12.2617699 Published: 2022Abstract:Recovering information of an object hidden behind turbid media has a vast range of applications. People have been trying many ways to achieve this goal. In this paper, we use lensless Fourier transform digital holography and statistical average to retrieve object information from speckle field. The relationship between parameters of ground glass and peak signal-tonoise ratio of reconstructed image is explored by establishing a rotating ground glass interferometric imaging system. The light beam emitted from the laser is divided into two beams by the beam splitter. One beam passes through the rotating ground glass after being reflected by the object (i.e. object light), and the other beam passes through the reflector and convex lens as a reference light, and then interferes with the object light. Finally the interference speckle pattern is captured by a CCD camera. Experiment results show that there is an optimal solution between the rotation speed of ground glass and the peak signal-to-noise ratio of the reconstructed image.This method has the advantages of compact system construction, easy implementation and fast reconstruction, since it does not require phase correction, complex image processing, scanning object or wavefront shaping. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20220911734953 -
Record 176 of
Title:Double-functionalization of water repellence and anti-reflectance by multiple-laser-based fabrication of triple-scale hierarchical surface structures
Author(s):He, Jianguo(1,2,3); Li, Ming(4); Dai, Shoujun(1,2); Huang, Min(1,3); Liu, Yang(1,3); Li, Yang(1,3); Fan, Lianwen(5); Yu, Jin(1,2)Source: Materials and Design Volume: 219 Issue: DOI: 10.1016/j.matdes.2022.110734 Published: July 2022Abstract:A novel strategy of laser ablation followed by tungsten-based pulsed laser deposition was proposed and experimentally verified for available surface functionalization with superhydrophobicity and anti-reflectance on 316L stainless steel. Three surface patterns, crater, parallel lines (PL), and grid, were manufactured by nanosecond laser ablation, while the surface morphology was controlled by the transverse traverse index. After the pulsed laser deposition treatment, tungsten particles and clusters were densely coated on the laser-ablated surfaces. The fabricated substrates were characterized by triple-scaled hierarchical structures having different patterns, corrugated structures, and broccoli-like nano-protrusions. An aging treatment was performed to improve wettability. The results verified that the proposed multiple laser treatments in combination with the aging treatment allow the quick implementation of superhydrophobicity while maintaining good reflectance over the spectral range. Moreover, the topology was characterized using an optical profiler and through scanning electron microscopy, while a video-based optical contact angle measuring device and spectrophotometer were used to measure the contact angle and optical reflectance, respectively. X-ray photoelectron spectroscopy was performed to analyze the chemical components. This method can prepare water-repellent anti-reflectance hybrid substrates for industrial and academic applications. ? 2022 The AuthorsAccession Number: 20222112157725 -
Record 177 of
Title:Simulation and experimental investigation on linear expansion micro-stress assembly process of adhesive bonded mirror
Author(s):Zheng, Xiang-Ke(1); Kang, Shi-Fa(1); Wang, Peng(1); Li, Hua(1); Shu, Lin-Sen(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12169 Issue: DOI: 10.1117/12.2623637 Published: 2022Abstract:In order to quickly obtain the effect of different bonding process on the surface-shape of the adhesive bonded mirror, the simulation and experimental study of the linear expansion micro-stress assembly process were carried out.The mathematical expression of the solidification micro-stress of the adhesive in plane mirror assembly is derived based on the volume shrinkage rate. The structural stiffness of the mirror and the frame is also taken into the mathematical expression of the micro-stress.A finite element model named "Mirror-Adhesive -Frame" was developed using ANSYS Parametric Design Language (APDL) and User Interface Design Language (UIDL) to calculate the PV and RMS values of the surface-shape of the mirror after bonding.The ZYGO interferometer is used to measure the PV and RMS values of the surface-shape index before and after the bonding of the mirror with a specification of ?100mm-15mm. By comparing the experimental results and the simulation results, the correction value of the equivalent linear expansion parameter of the adhesive layer is obtained. Then, the corrected equivalent linear expansion coefficient of the adhesive layer is brought into the simulation model to predict the PV and RMS values. The results show that the prediction results of the developed simulation model are in good agreement with the measurement results. Moreover, it is found that when the circumference and back of the mirror are both bonded, the PV and RMS values of the surface-shape reach the maximum, and the PV and RMS values are 0.187? and 0.044?, respectively. ? 2022 SPIEAccession Number: 20221611967855 -
Record 178 of
Title:Period-timing bifurcation evolution in a nonlinear polarization rotation fiber laser
Author(s):Ban, Xiaoqiang(1,2); Li, Xiaohui(3); Dong, Bo(4); Huang, Wobin(4); Zhong, Ming(5); Little, Brent E.(1,2)Source: Optik Volume: 268 Issue: DOI: 10.1016/j.ijleo.2022.169870 Published: October 2022Abstract:Period-timing bifurcation phenomenon widely exists in fiber laser. We investigate the period-timing bifurcation phenomenon in fiber resonator. Large period-timing of single pulse occurs due to mutual competition between dispersive wave and soliton. In addition, period-timing of soliton molecule is observed due to mutual attraction and repulsion between adjacent pulses. Furthermore, local periodic bifurcation has been obtained. All the period-timing bifurcation phenomena are related to many factors such as fiber birefringence, small signal gain, nonlinear effect and dispersion, etc. Exploring period-timing bifurcation is helpful to understand the dynamic evolution of pulse. Period-timing bifurcation has important applications in optical communication system, optical logic operation, all-optical computing and so on. ? 2022 Elsevier GmbHAccession Number: 20223512639069 -
Record 179 of
Title:All-Optical Tunable Fiber Filter With Dual Graphene Films Enabled by a Fiber Open Microcavity
Author(s):Li, Yang(1); Dong, Bo(2); Chen, Enqing(3); Li, Ziwan(1,3,4)Source: Journal of Lightwave Technology Volume: 40 Issue: 7 DOI: 10.1109/JLT.2021.3135314 Published: April 1, 2022Abstract:An all-optical tunable fiber filter with dual graphene films enabled by a fiber open microcavity. The graphene films are deposited on the fiber end surfaces via the light induced thermophoresis effect. Two fiber end surfaces deposited with the graphene films are used to construct the microcavity. Under an additional 980-nm optical pump, the filter experiences stronger optical Kerr effect and photothermal effect since the light propagates to the dual graphene films repeatedly. Experimental results show that its all-optical tunable wavelength range can reach 8.295 nm within the optical pump power range of 0～80 mW, and it is almost 23.8 times of the reported all-optical tunable Fabry-Perot filter. ? 2022 IEEE.Accession Number: 20215211398418 -
Record 180 of
Title:Position-sensitive Micro-channel-plate Having Cross-delay-line Detector Based Photon-counting Three-dimensional Super-resolution Laser Imaging（Invited)
Author(s):Zhao, Hui(1); Yin, Haomeng(1,2); Liu, Yongan(1); Shen, Lizhi(1); Yang, Xianghui(1); Zou, Gangyi(1); Xia, Siyu(1); Yang, Mingyang(1,2); Fan, Xuewu(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 7 DOI: 10.3788/gzxb20225107.0751407 Published: July 2022Abstract:Laser-based active detection and imaging is where the space situational awareness heading in the future. The photon-sensitive detector is the core of the photon-counting-based three-dimensional laser imaging system whose working range is much longer and which is capable of realizing both high-precision distance measurement and three-dimensional surface reconstruction at the same time. Therefore，the photon-counting-based three-dimensional laser imaging is especially suitable for realizing ranging and three-dimensional imaging of distant space targets in a deep space background. In this manuscript，the position-sensitive Micro-channel-plate with Cross-delay-line （MCP/CDL） detector-based photon-counting three-dimensional imaging technique is proposed. First of all，the research background of this manuscript is systematically introduced and the contribution of the work reported to the field of photon-counting-based three-dimensional laser imaging is summarized. After that，starting from the characteristics of the MCP/CDL detector itself，the photon-counting three-dimensional laser imaging system by using the position-sensitive MCP/CDL detector is designed and the corresponding operating mode is discussed simply，which gives a reference for real application in future. After that，the principle of the proposed position-sensitive MCP/CDL detector-based photon-counting three-dimensional laser imaging technique is introduced from two aspects. In the one hand，how to use MCP/CDL detector to realize the synchronous timing and positioning of arriving photon is qualitatively explained. On the other hand，with the help of the classical LIDAR equation，the echo power model and the echo photon model generated from the echo power model are given respectively. Based on the two basic models，three important models including the signal to noise ratio model，detection probability model，and ranging accuracy model are derived one by one， based on which the performance of the proposed technique is investigated numerically. After establishing the all-chain imaging model，the potentials of this technique in space-borne space targets monitoring are investigated through end-to-end simulated imaging and performance analysis. By using the Monte Carlo simulation method，the simulated photon-counting three-dimensional laser imaging is carried out with different conditions and in this way，the potential performance of this system in space situational awareness is demonstrated vividly. However，nowadays，most photon-counting detectors including the MCP/CDL detector have a low spatial resolution. In this case，the ranging imaging has a strong mosaic effect which is hard to resolve finer details. Besides that，the ranging accuracy is mainly determined by timing electronics. Considering these two situations，how to improve the spatial and temporal resolution is also discussed. Taking the finer details provided by the higher resolution intensity image as reference，the spatial resolution of ranging images could be improved prominently. At the mean time，a controllable time delay is introduced to realize super-sample in ranging direction and the higher ranging accuracy could be obtained by fusing multiple range images. According to numerical simulations，the potential of this system in realizing super-resolution both in the spatial domain and in the temporal domain is demonstrated. Finally，the prototype camera using MCP/CDL detector is designed，tested and fabricated. By using the prototype camera，two groups of three-dimensional laser imaging experiments are carried out. The results demonstrate that this technique has the capability in resolving small distance variation of being less than 5 mm when the imaging distance is about 6.8 m. Therefore，the position-sensitive micro-channel-plate having cross-delay-line based photon-counting three-dimensional laser imaging is proven to be effective. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20223612691739