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Record 193 of
Title:Spatial coupling efficiency of collimators based on gradient-index lens with an angle polish
Author(s):Song, Wei(1,2,3); Xie, Youjin(1,2); Hao, Wei(1,2); Han, Junfeng(1,2); Yan, Peipei(1,2); LI, Xin(1,2); Wang, Yifan(1,2); Li, Xiangyu(1,2); Sun, Chuandong(1); Li, Zhiguo(1,2)
Source: Optics and Laser Technology Volume: 162 Issue: null Article Number: 109245 DOI: 10.1016/j.optlastec.2023.109245 Published: July 2023
Abstract:As high coupling efficiency and return loss are crucial in fiber-optic transmission systems, they have attracted widespread attention. This study proposes a ray-transfer matrix-based mathematical analysis method and experimentally demonstrates a collimator based on a gradient-index lens with an angle polish. The propagation characteristics and coupling mechanisms of the collimators are introduced. A beam-steering technology based on a wedge prism and flat glass is proposed to improve the coupling efficiency of the Gaussian beam using collimators. The proposed method is validated via simulation and experiment. The results are significant in free-space optical communication, optical signal processing, and optical fiber connectors. ? 2023 Elsevier Ltd
Accession Number: 20230713598459
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Record 194 of
Title:Position linearity analysis of circular arc terminated resistive anode using finite element method for photon-counting imaging detectors
Author(s):Yang, Kai(1,2); Bai, Yonglin(1,2); Cao, Weiwei(1); Yang, Yang(1); Zhu, Bingli(1); Zheng, Jinkun(1); Bai, Xiaohong(1); Chen, Zhen(1); Wang, Bo(1,2)
Source: Review of Scientific Instruments Volume: 94 Issue: 1 Article Number: 013703 DOI: 10.1063/5.0118899 Published: January 1, 2023
Abstract:This study proposes a comprehensive model of the circular arc terminated (CAT) resistive anode based on the finite element method to explore the dynamic process of charge diffusion on this anode and its position linearity performance. The waveforms of charges of the electrodes on the anode are calculated for different electrical parameters and their influence on positional linearity is investigated. The influence of the signal development time and the non-uniformity of the resistance per square of the anode on positional linearity is also analyzed. The results of simulations show that the non-linearity of the image varies monotonically with the termination resistance and the non-uniformity of the resistance per square of the anode, but has a non-linear relationship with the signal development time and the ratio of the resistance per square. A CAT resistive anode with capacitance c and a resistance per square of the sensitive area of R can be used to recover an image with a root mean-squared non-linearity of 2%, when the charge signals of the electrode are collected for at least 0.6R s. The reliability of the results of the simulations was verified with experimental measurements. ? 2023 Author(s).
Accession Number: 20230513536677
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Record 195 of
Title:Imaging Linearity Modeling and Optimization of Capacitive Division Image Readout (C-DIR) for Microchannel Plate Imaging Detectors
Author(s):Yang, Kai(1,2); Bai, Yonglin(1,2); Zhu, Bingli(1); Wang, Bo(1,2); Cao, Weiwei(1,2); Zhang, Shengdan(1,2); Bai, Xiaohong(1,2); Zheng, Jinkun(1,2); Yang, Yang(1,2); Chen, Zhen(1,2)
Source: IEEE Transactions on Nuclear Science Volume: 70 Issue: 7 Article Number: null DOI: 10.1109/TNS.2023.3265720 Published: July 1, 2023
Abstract:A 3-D lumped parameter circuit model based on the nodal analysis to simulate signal propagation and position response characteristics of capacitive division image readout (C-DIR) is proposed. The current pulses, charge collection efficiency, and position reconstruction patterns are calculated for different electrical parameters (charge division capacitor Cc , perimeter capacitor Cp , diagonal capacitor Cd, electrode parasitic capacitor Cs, and the sheet resistance of the resistive layer R Ge, and their influence on imaging linearity is investigated. The simulation results show that R Ge affects the amplitude, pulsewidth, and polarity of the current pulse in the C-DIR. The sheet resistance of the resistive layer needs to be larger than 10 M for the charge to be efficiently collected by the readout electronics. Several capacitance ratios ( Cc/Cp,Cc, and Cc/Cd) mainly affect the imaging linearity. It has been found that to obtain good detector imaging performance, Cc/Cp should be less than 0.01, Cc/Cs should be larger than 100, and Cc/Cd should be larger than 10, and when R Ge is larger than 10 M , the imaging nonlinearity (rms) can be less than 1%. The reliability of the simulation results was verified by experimental measurements of a prototype C-DIR detector designed by ourselves. An optimized imaging performance with imaging nonlinearity (rms) of 2.18% was achieved. ? 1963-2012 IEEE.
Accession Number: 20231714014766
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Record 196 of
Title:Research on key technologies of hyperspectral imaging system for spaceborne water environment remote sensing monitoring
Author(s):Song, Shuyao(1,2); Liu, Xiao(1); Wang, Xueji(1); Liu, Yuyang(1,2); Liu, Hong(1); Liu, Jiacheng(1); Yu, Tao(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12558 Issue: null Article Number: 125580D DOI: 10.1117/12.2651498 Published: 2023
Abstract:In order to realize space-based remote sensing for river, lake and ocean environment monitoring and break through the key technology of hyperspectral imaging system, based on the Ritchey-Chrétien (R-C) Cassegrain folding reflector telescope, we designed a front telescope system with a working altitude of 600 km, a working spectral band of 450-900 nm, a full field of view of 2.9°, a system focal length of 400 mm, the optical speed of F/4 and effective control of aberration and chromatic aberration of adding three-piece correction mirror to control the field of view is designed. The initial structural parameters of the front telescope system are solved according to the primary aberration theory, and the secondary mirror blocking ratio of the front telescope system is designed to be 0.35, and the simulation and optimization design are carried out in ZEMAX software. The system performance analysis shows that more than 80% of the energy of the imaging spot is concentrated within 12 μm.The maximum aberration is 0.78% and the maximum magnification chromatic aberration is 1.26 μm.The RMS (Rate-Monotonic Scheduling) radius of spot at all fields of view and wavelengths in the point column diagram is less than 2.6 μm (Airy radius is 3.3 μm). At the Nyquist frequency of 25 lp / mm, the MTF (Modulation Transfer Function) values of each spectral section in all fields of view are greater than 0.8.All the above evaluation indexes meet the performance requirements of hyperspectral imaging system ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20230713574399
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Record 197 of
Title:Analysis of coverage of the near space spaceborne wind interferometer
Author(s):Wen, Zhenqing(1,2); Feng, Yutao(1); Fu, Di(1,2); Zhu, Jun(3); Wang, Chao(3)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 52 Issue: 10 Article Number: 20230106 DOI: 10.3788/IRLA20230106 Published: October 2023
Abstract:Objective Spaceborne wind interferometer uses the limb observation mode to measure the Doppler shift of atmospheric airglow lines to realize atmospheric wind field detection. The effective coverage of interferometer will be limited by the source and satellite mode. It is of great significance for the application of wind field data to analyze the observation data at the front end of satellite mission planning to determine whether it meets the scientific objectives. Methods According to the satellite orbit parameters and the instrument boresight parameters, the geometric model of limb observation is established (Fig.1), and the distribution of limb tangent points of instruments during satellite operation is simulated. Then, the main factors affecting the effective observation of the instrument are discussed, and the relationship between the solar incidence angle and the effective spatio-temporal coverage of the interferometer at different time periods is analyzed by taking the detection of dayglow as an example (Fig.5). Finally, the method of variable separation is applied to study the influence of satellite orbit parameters on the effective coverage of the wind interferometer, and the coverage percentage of the interferometer under different orbit parameters on the Eurasian is evaluated. Results and Discussions 1) The main factors affecting the effective observation of the instrument are the zenith angle and the scattering angle of the sun. The solar incidence angle affects both the latitude coverage and the local time of the tangent point. (Fig.6-8). 2) The coverage efficiency of the instrument is affected by both orbital inclination and orbital altitude. Moreover, orbital inclination is the main orbital parameter affecting the coverage percentage of Eurasia continent. When the orbital inclination is between 60° and 80°, the coverage percentage can reach 100% (Fig.12). Conclusions This paper provides an observational geometric framework for the subsequent design and performance evaluation of the spaceborne interferometer, and realizes the quantitative analysis of the coverage efficiency of payload observation. The model has the ability to be widely used in the analysis of observation models of other types of atmospheric optical remote sensing payloads. ? 2023 Chinese Society of Astronautics. All rights reserved.
Accession Number: 20234515031255
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Record 198 of
Title:Design of three-class ultra-efficient stray light suppression baffle
Author(s):Jin, Yu(1,2); Lin, Shangmin(1,2); Wang, Hu(1,2); Qiao, Jiang(1,2); Yan, Haoyu(1,2); Wang, Xingyan(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12585 Issue: null Article Number: 1258504 DOI: 10.1117/12.2668091 Published: 2023
Abstract:The ultra-efficient standard light baffle plays an important role in the calibration of the stray light test system. In this paper, a three-class baffle is designed. And a design scheme of the baffle with honeycombed wall is proposed, by analyzing the stray light transmission model and suppression mechanism, which can meet the requirements of a baffle with ultra-efficient stray light suppression capability. A simulation model of the baffle was established. The simulation of baffle show that when the stray light suppression angle is greater than 8°, the PST value of the baffle reaches 10-6 magnitude. When the stray light suppression angle is greater than 17°, the PST value of the baffle reaches 10-12 magnitude, which can meet the needs of ultra-efficient calibration of laboratory stray light test systems. ? 2023 SPIE.
Accession Number: 20232114113546
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Record 199 of
Title:Performance Analysis of STAR-IRS Aided NOMA Short-Packet Communications with Statistical CSI
Author(s):Xu, Jing(1); Yuan, Lei(1); Yang, Nan(1); Yang, Nan(2); Guo, Yi(3)
Source: IEEE Transactions on Vehicular Technology Volume: 72 Issue: 9 Article Number: null DOI: 10.1109/TVT.2023.3266830 Published: September 1, 2023
Abstract:We analyze the benefits of simultaneous transmitting and reflecting intelligent reflecting surfaces (STAR-IRSs) for short-packet communications (SPC) with non-orthogonal multiple access (NOMA) and statistical channel state information towards ultra-reliable and low-latency communications. Considering Rician fading and energy splitting protocol, we analyze the performance of STAR-IRS aided NOMA SPC systems with continuous and discrete phase shifts. We first derive new closed-form expressions for the average block error rate (BLER) and diversity order in the finite signal-to-noise ratio (SNR) regime. We then determine the relationship among the average BLER, power allocation, blocklength, and transmission and reflection coefficients. Finally, Monte Carlo simulations are used to verify our theoretical analysis and examine the optimal transmission and reflection coefficients that minimize the common blocklength in the considered system under reliability constraints. ? 1967-2012 IEEE.
Accession Number: 20231714015953
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Record 200 of
Title:Coincidence time resolution measurements for dual-ended readout PET detectors
Author(s):Sun, M.D.(1); Zhang, C.H.(2); Zhao, B.Q.(3)
Source: Journal of Instrumentation Volume: 18 Issue: 7 Article Number: P07003 DOI: 10.1088/1748-0221/18/07/P07003 Published: July 1, 2023
Abstract:Coincidence time resolution (CTR) is an important performance parameter of clinical positron emission tomography (PET) detectors, which is dependent on the parameters of the scintillation crystal, the timing measurement methods, and the electronics. In this work, CTRs of PET detectors using dual-ended readout of segmented LYSO arrays were measured with different timing measurement methods. The detector modules were composed of LYSO arrays of 8 × 8 with a crystal size of 3.10 × 3.10 × 20 mm3 or 13 × 13 with a crystals size of 1.88 × 1.88 × 20 mm3, coupled at each end to an 8 × 8 Hamamatsu SiPM array (S13361-3050NE-08) with pixel active area of 3.00 × 3.00 mm2 and pitch of 3.20 mm. The signals of the SiPM arrays were individually read out and processed by using the TOFPET2 ASICs. The CTRs of the detectors were measured after the timing alignment of the ASICs was performed. Timing measurement methods of the dual-ended readout detector such as the average time of the two SiPMs, the faster time of the two SiPMs, the time of the back SiPM, and the time of the front SiPM were compared. The average time of the two SiPMs provides the best CTR, which is explained by a simple model about the timing measurement methods of a dual-ended readout detector. The detector with one-to-one crystal-to-SiPM coupling provides better CTR than the detector with a crystal size smaller than the pixel size of the SiPM. The best CTR of 367 ± 6 ps was obtained by using the 8 × 8 LYSO array with unpolished lateral crystal surfaces and ESR reflectors. The CTR of the dual-ended readout detector can be improved if a DOI-dependent timing correction is used. ? 2023 IOP Publishing Ltd and Sissa Medialab
Accession Number: 20232814389243
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Record 201 of
Title:Various-order soliton molecule evolution in a fiber laser with nonlinear polarization rotation effect
Author(s):Ban, Xiaoqiang(1,2); Li, Xiaohui(3); Zhong, Ming(4); Little, Brent E.(1,2)
Source: Microwave and Optical Technology Letters Volume: 65 Issue: 5 Article Number: null DOI: 10.1002/mop.33406 Published: May 2023
Abstract:The generation and evolution of soliton molecules are investigated theoretically with the coupled nonlinear Schrodinger equations?based on a vector field. The formation of second-and third-order soliton molecules is investigated. Besides this, various-order soliton molecules from the 6th order to the 13th order have been observed by adjusting small-signal gain and phase delay. Finally, we analyze the reason for the soliton molecule generation. Exploring soliton molecules is helpful for optical communication as well as for fiber laser design. ? 2022 Wiley Periodicals LLC.
Accession Number: 20222812337743
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Record 202 of
Title:Improved structure for the dissipative soliton generation based on nonlinear polarization rotation effect
Author(s):Ban, Xiaoqiang(1,2); Li, Xiaohui(3); Zhong, Ming(4); Little, Brent E.(1,2); Zhao, Wei(1,2)
Source: Microwave and Optical Technology Letters Volume: 65 Issue: 5 Article Number: null DOI: 10.1002/mop.33199 Published: May 2023
Abstract:Nonlinear polarization rotation (NPR) technique has been studied for several decades to investigate the ultrafast pulse in both scientific and industrial fields. However, some drawbacks such as sensitive to the environment, noncompact, difficult to reach all the polarization states limit the real applications of this methods. In this work, an improved NPR technique, with polarizar-polarization controlar-polarizar structure, has been proposed for the first time. The new structure is relatively more simple to reach all the polarization states and remains much more stable states than traditional NPR technique. We proposed all-normal-dispersion Yb-doped fiber laser and rectangular-shaped spectrum is obtained both experimentally and theoretically by improved NPR technique. The achieved stable pulse duration and pulse period are 11.69 ps and 37.2 ns, respectively. Signal-to-noise ratio is 64 dB at 26.9?MHz, thus the proposed fiber laser has very high stability. Besides, we investigate the output spectrum and pulse shape based on dispersive Fourier transformation, getting the right triangle and ordinary triangle spectrums that are symmetric with the corresponding pulse shapes. ? 2022 Wiley Periodicals LLC.
Accession Number: 20220711646734
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Record 203 of
Title:Two-frame advanced iterative self-tuning algorithm for accurate phase retrieval
Author(s):He, Zhouxuan(1); Du, Hubing(1); Gu, Feifei(4); Hu, Bingqing(1); Wang, Feng(2); Zhao, Zixin(3); Zhang, Gaopeng(2)
Source: Optics and Lasers in Engineering Volume: 169 Issue: null Article Number: 107715 DOI: 10.1016/j.optlaseng.2023.107715 Published: October 2023
Abstract:Two-shot random phase-shifting interferometry has been actively investigated and improved owing to more demanding requirements in investigating dynamic phenomena or sensing some transient events. Given the background intensity and phase step knowledge, a reconstruction algorithm can be used to recover a complex-valued signal from intensity-only measurements. Most algorithms assume the background intensity and modulation amplitude in a frame of interferogram are constant variables; however, in realistic systems, they vary laterally and axially across the field of view. The model can be used but often appears less precise. In this work, we propose an approach that leverages the iterative method to cope with spatially varying background intensity and modulation amplitude. Our approach, termed the two-frame advanced iterative self-tuning algorithm, uses the spatial mean algorithm paired with an iterative procedure to search the phase step from two captured fringe patterns. It represents a novel approach to reliable and practical two-step phase-shifting interferometry without pre-filtering due to the cancelation of simultaneously obtaining the phase shifts and measured phase through iterative operation in the spatial–temporal domain. Experimental results obtained using the proposed method indicate that it is a simple and robust solution for phase extraction from a two-frame unknown phase shift fringe pattern with spatially varying background intensity and modulation amplitude. ? 2023 Elsevier Ltd
Accession Number: 20232614306943
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Record 204 of
Title:Effect of Zn Diffusion on Avalanche Breakdown Probability of InGaAs/InP Single Photon Avalanche Diodes
Author(s):Guo, Kefei(1,2); Yin, Fei(1,2); Liu, Liyu(1,2); Qiao, Kai(1,2); Li, Ming(1); Wang, Tao(1,2); Fang, Mengyan(1,2); Ji, Chao(1,2); Qu, Youshan(1,2); Tian, Jinshou(1,2); Wang, Xing(1,2)
Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 52 Issue: 6 Article Number: 0604001 DOI: 10.3788/gzxb20235206.0604001 Published: June 2023
Abstract:Single photon detection technology is a very sensitive photoelectric detection technology that can detect the energy of a single photon. It is a weak signal detection technology widely used in laser ranging，quantum communication，laser radar 3D imaging，and other fields. Single photon avalanche diodes generally operate in Geiger mode，that is，the operating voltage is greater than the breakdown voltage. Photon detection efficiency refers to the probability that a photon incident on a device is converted into a macroscopic signal that can be detected. It is an important parameter to measure the detection ability of single photon avalanche diodes. InGaAs/InP single photon avalanche diodes can work in near infrared band，has the characteristics of high photon detection efficiency and good time jitter，in addition to small size，high stability，excellent anti-radiation performance，can realize large array imaging and other advantages，become one of the most promising near infrared single photon detectors. The planar back-illuminated InGaAs/InP single photon avalanche diodes designed in this paper adopt the absorption grading charge multiplication separation structure，in which the charge layer can control the electric field intensity of the multiplier layer to be high enough to produce avalanche breakdown，while the absorption layer electric field intensity is limited to a certain range to reduce the tunneling effect. The grading layer can reduce the accumulation of carriers at the heterogeneous interface. The P+ active region is formed by two Zn diffusion structures，the multiplication region is limited to the area below the deep diffusion. The shallow diffusion can effectively limit the edge electric field of the multiplication region without using the guard ring structure to avoid premature edge breakdown. The structure design and numerical simulation of InGaAs/InP single photon avalanche diodes are carried out by using TCAD software and selecting the appropriate physical model and parameters，and the corresponding electrical and optical parameters are obtained. Then aiming at the effect of avalanche breakdown probability on device photon detection efficiency，the relationship between the avalanche breakdown probability of the device and the difference between the two Zn diffusion depths，the lateral diffusion factor of Zn diffusion，the doping concentration of Zn，and the temperature parameters is emphatically studied. It is found that when the depth of deep diffusion is 2.3 μm，there is an optimal target value corresponding to the shallow diffusion depth. The deeper the shallow diffusion depth，the higher the breakdown probability of avalanche in the center of the multiplication region under the same overbias，and the higher the electric field intensity will also increase. However，when the difference between the two Zn diffusion depths is less than 0.6 μm，non-ideal breakdown will occur outside the multiplication region，resulting in an increase in the dark count of the device. The larger the lateral diffusion factor of Zn diffusion， the higher the breakdown probability of the avalanche at the center of the multiplication region， and the lower the breakdown probability of the avalanche at the edge of the multiplication region. With the same diffusion depth，the shallow diffusion Zn doping concentration has no significant effect on avalanche breakdown probability， but the higher the deep diffusion Zn doping concentration，the lower the avalanche breakdown probability under the same overbias. The study of the influence of temperature on avalanche breakdown probability shows that the device can obtain better performance at low temperature. The research work in this paper can guide the design of InGaAs/InP single photon avalanche diodes with higher photon detection efficiency and lower dark count. Moreover，relevant research can also provide a reference for selecting the optimal working point of the device to ensure the device works in the best state and realize the optimal application of the device. ? 2023 Chinese Optical Society. All rights reserved.
Accession Number: 20233014444710
