2020
2020
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Record 493 of
Title:Photonic perceptron based on a Kerr microcomb for high-speed, scalable, optical neural networks
Author(s):Xu, Xingyuan(1,2); Tan, Mengxi(1); Wu, Jiayang(1); Boes, Andreas(3); Corcoran, Bill(2); Nguyen, Thach G.(3); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6); Mitchell, Arnan(3); Hicks, Damien G.(1,7); Moss, David J.(1)Source: 2020 International Topical Meeting on Microwave Photonics, MWP 2020 - Proceedings Volume: Issue: DOI: null Published: November 24, 2020Abstract:Optical artificial neural networks (ONNs) have significant potential for ultra-high computing speed and energy efficiency. We report a new approach to ONNs based on integrated Kerr micro-combs that is programmable, highly scalable and capable of reaching ultra-high speeds, demonstrating the building block of the ONN - a single neuron perceptron - by mapping synapses onto 49 wavelengths to achieve a single-unit throughput of 11.9 Giga-OPS at 8 bits per OP, or 95.2 Gbps. We test the perceptron on handwritten-digit recognition and cancer-cell detection - achieving over 90% and 85% accuracy, respectively. By scaling the perceptron to a deep learning network using off-the-shelf telecom technology we can achieve high throughput operation for matrix multiplication for real-time massive data processing. ? 2020 IEICE.Accession Number: 20210609881364 -
Record 494 of
Title:Mobile person re-identification with a lightweight trident CNN
Author(s):Xiong, Mingfu(1); Chen, Dan(2); Lu, Xiaoqiang(3)Source: Science China Information Sciences Volume: 63 Issue: 11 DOI: Published: November 1, 2020Abstract:nullAccession Number: 20201708553492 -
Record 495 of
Title:Remote Sensing Road Extraction by Refining Road Topology
Author(s):Gao, Huiqin(1,2); Yuan, Yuan(3); Zheng, Xiangtao(1)Source: Lecture Notes in Electrical Engineering Volume: 657 Issue: DOI: 10.1007/978-981-15-3947-3_14 Published: 2020Abstract:Remote sensing road extraction is one of the research hotspots in high-resolution remote sensing images. However, many road extraction methods cannot hold the edge interference, including shadows of sheltered trees and vehicles. In this paper, a novel remote sensing road extraction (RSRE) method based on deep learning is proposed, which considers the road topology information refinement in high-resolution image. Firstly, two parallel operations, which named dilation module (DM) and message module (MM) in this paper, are embedded in the center of semantic segmentation network to tackle the issue of incoherent edges. DM containing dilated convolutions is used to capture more context information in remote sensing images. MM consisting of slice-by-slice convolutions is used to learn the spatial relations and the continuous prior of the road efficiently. Secondly, a new loss function is designed by combining dice coefficient term and binary cross-entropy term, which can leverage the effects of different loss. Finally, extensive experimental results demonstrate that the RSRE outperforms the state-of-the-art methods in two public datasets. ? 2020, Springer Nature Singapore Pte Ltd.Accession Number: 20202908937137 -
Record 496 of
Title:Fabrication of refractive silicon microlens array with a large focal number and accurate lens profile
Author(s):Zhou, Xiaojun(1); Song, Aiguo(1); Wang, Shuai(2); Wang, Mengjia(3); Yu, Weixing(2)Source: Microsystem Technologies Volume: 26 Issue: 4 DOI: 10.1007/s00542-019-04644-4 Published: April 1, 2020Abstract:In this paper, we demonstrate the fabrication of refractive silicon microlens array with a large focal number and almost perfect spherical lens shape. Through a modified thermal reflow, photoresist microlens array of a large focal number is fabricated, which is then transferred into the silicon substrate by ion beam milling. To reach an accurate spherical lens profile, we both theoretically and experimentally study the practical factors that harm the pattern transfer fidelity, which mainly include the etching selectivity and faceting effect. Other secondary etching effects, such as the trenching effect and re-deposition effect, are also discussed. Based on these studies, a silicon microlens array with a focal number of 1.35 has been successfully obtained, with the profile error controlled well-below 0.121?μm, less than λ/6 within the whole infrared wavelength band. Besides, the fabricated microlens array exhibits a good uniformity and fine surface smoothness. The fabricated silicon microlens arrays can be applied in minatured infrared and terahertz imaging devices, or used as the master mould for soft lithography. ? 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Accession Number: 20195107871414 -
Record 497 of
Title:Asymmetric near-zero edge mode in topological photonic lattice without chiral or particle-hole symmetries
Author(s):Ji, Kaiwen(1); Liu, Zhenjuan(1); Dai, Yanan(1); Wen, Zengrun(2); Wang, Yishan(4); Zhang, Guoquan(3); Bai, Jintao(2); Qi, Xinyuan(1,2)Source: Optics Letters Volume: 45 Issue: 1 DOI: 10.1364/OL.45.000049 Published: January 1, 2020Abstract:Generally speaking, a one-dimensional system requires chiral or particle-hole symmetry to be topologically nontrivial. In this Letter, we show that topological behavior can also be observed in a quasi-one-dimensional photonic system without the aforementioned symmetries. The results indicate that the quantized Zak phase is achieved in such a system even though the chiral and particle-hole symmetries are still absent. Further study shows that the system can support a topologically protected asymmetric near-zero mode on the right edge. Our work enriches the concepts of design of topological photonics and may have important applications in future quantum computations. ? 2019 Optical Society of America.Accession Number: 20200207991279 -
Record 498 of
Title:High-precision long-distance measurement with an intensity-modulated frequency comb
Author(s):Li, Guicun(1,2); Fang, Yami(1,2); Zhang, Hao(1,2); Sun, Jun(1,2); Liu, Zongming(1,2); Song, Ting(1,2); Ji, Rongyi(3); Wang, Yishan(4)Source: Applied Optics Volume: 59 Issue: 24 DOI: 10.1364/AO.398290 Published: August 20, 2020Abstract:We describe an improved synthetic wavelength method for high-precision long-distance measurement with a repetition-rate-locked femtosecond laser modulated by a fiber Mach–Zehnder electro-optic intensity modulator. Harmonics of the repetition rate accompanied with modulating sidebands will be generated via intermode beating, which will be utilized for high-precision ranging. The nonambiguity range is significantly extended with a relatively low modulation frequency, and the ambiguous distance is unwrapped by synchronous phase-shift measurements of a synthetic wavelength chain without any auxiliary measurement operation. Our experiment shows a precision better than 20 μm at 46 m range, and a high-precision translation stage is applied for preliminary test and proof-of-principle demonstration. The demonstrated system is simple and can be easily integrated, and it will find widespread applications in large-scale metrology such as large-volume manufacturing and precision formation flying. ? 2020 Optical Society of AmericaAccession Number: 20203609121420 -
Record 499 of
Title:Estimation variance of dual-rotating-retarder Mueller matrix polarimeter in the presence of Gaussian thermal noise and poisson shot noise
Author(s):Quan, Naicheng(1,2); Zhang, Chunmin(3); Mu, Tingkui(3); Li, Siyuan(2); You, Caiyin(1)Source: Journal of Optics (United Kingdom) Volume: 22 Issue: 2 DOI: 10.1088/2040-8986/ab613c Published: 2020Abstract:In this paper, the close-form functions of estimation variances on the elements of the measured Mueller matrix for a dual-rotating-retarder Mueller matrix polarimeter with a rotating frequency ratio of 5ω:Nω (N = 1, 2, 3, 4, 6, 7, 8, 9) are addressed by theoretical analysis and simulations in the presence of additive Gaussian noise and signal-dependent Poisson shot noise, which are two dominant types of noise in the most commonly used detectors. The results provide a clear insight into the estimation precision of each Mueller matrix element. It is found that (1) estimation variances on each element of the Mueller matrix are heavily dependent on the retardances of the retarders and inversely proportional to the number of measurements; (2) for Gaussian noise, estimation variances are independent of rotating frequency ratio and dual 130.18° retardances can minimize the total variance of the 16 estimated Mueller matrix elements at a fixed number of measurements; (3) for Poisson noise, the estimation variances are only dependent on four elements of the Mueller matrix under test when the rotating frequency ratio of 5ω:7ω is used; (4) the retardance in the range from 126.43°-133.54° can result in a nearly-minimum total variance for both Gaussian and Poisson noise, whatever the observed Mueller matrix. These results are important for designing dual-rotating-retarder Mueller matrix polarimeters aimed at different types of applications and for assessing their performance. ? 2019 IOP Publishing Ltd.Accession Number: 20201008255006 -
Record 500 of
Title:Photochemical response triggered by ultrashort laser Gaussian-Bessel beams in photo-thermo-refractive glass
Author(s):Wang, Xu(1,2); Zhang, Guodong(3); Zhang, Yunjie(4); Xie, Xiaoping(1,2); Cheng, Guanghua(3); Li, Weinan(1)Source: Optics Express Volume: 28 Issue: 21 DOI: 10.1364/OE.401905 Published: October 12, 2020Abstract:Photosensitivity in photo-thermo-refractive (PTR) glass can be triggered by UV and near-infrared fs laser irradiation. Here we focus on the nonlinear photochemical process triggered by ultrashort laser Gaussian-Bessel beams. The transmission and absorption spectra show that the primary difference between UV and fs laser exposure is the formation of color centers and kinetic process of silver nanoparticles growth. It is contributed to the nonlinear ionization of PTR glass matrix and thermal effects during interaction of glass matrix and ultrashort laser pulses. Transmission electron microscopy verifies the generation of nanoscale crystals in the irradiated region, and X-ray diffraction shows the existence of quartz crystal and NaF after laser irradiation and thermal treatment. Moreover, the dependence of photochemical reaction on laser parameters is investigated, as well as the tailoring of silver nanoparticles. On this basis, volume Bragg gratings with ultrashort laser Gaussian-Bessel beams are inscribed as an application which possess good diffraction characteristics. ? 2020 Optical Society of America under the terms of the OSA Open Access Publishing AgreementAccession Number: 20204409411993 -
Record 501 of
Title:Colourful imaging and self-reconstruction properties of modified single-focus fractal zone plates
Author(s):XIA, TIAN(1,2,3); CHENG, SHUBO(4); TAO, SHAOHUA(1,5); YU, WEIXING(2)Source: Optics Express Volume: 28 Issue: 25 DOI: 10.1364/OE.409680 Published: December 7, 2020Abstract:A modified single-focus fractal zone plate (MSFFZP) is proposed to generate a single main focus with many subsidiary foci or two equal-intensity main foci with many subsidiary foci. Widths of high-transmission zones, which have influence on the number of the high-order diffraction foci, such as the second-order focus and the fourth-order focus, can adjust first-order fractal focal intensities, but have no influence on first-order focal positions. Moreover, the MSFFZPs have the first-order foci or the first and second order foci only along the optic axis. It is proved numerically and experimentally that the MSFFZP can generate one or two colourful images with the low chromatic aberrations at the focal planes, and the MSFFZP beam has the self-reconstruction property. In addition, the MSFFZP produces a series of foci at the different focal planes along the optic axis in the simulations and experiments. The method of constructing the MSFFZP is illustrated. The proposed zone plate can be used to produce the multiple clear images, trap particles at the multiple planes simultaneously, and generate the images with the low chromatic aberration. ? 2020 Optical Society of America.Accession Number: 20205009603190 -
Record 502 of
Title:Integrating design of a compact optical system for ultra-stable laser system
Author(s):Zhang, Linbo(1,2,3); Chen, Long(1); Xu, Guanjun(1); Liu, Jun(1); Guo, Xinqian(1,3); Jiang, Chenhui(1,3); Fan, Le(1); Liu, Tao(1); Zhang, Shougang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11717 Issue: DOI: 10.1117/12.2585448 Published: 2020Abstract:As the local oscillator of the space optical clock, the ultra-stable laser determines the short-to-medium-term frequency stability of the space optical clock. Considering the space station's restrictions on load weight and volume, as well as the impact of vibration and shock during launch, a tunable external cavity diode laser with small size, stable structure and no elastic adjustment device was developed. Optimized the design of the structure of the optical path board, developed small optical components, and developed a double-sided optical path system based on this. Experimental tests show that the free-running line width of the laser is about 175 kHz, which can run stably and reliably for a long time. At the same time, considering the deformation of the optical path substrate in the space microgravity environment, the topology optimization design of the optical board was carried out. Through mechanical simulation analysis, the maximum deformation of the optical path substrate under the influence of gravity is 0.43 μm, which initially meets the requirements of space applications. ? 2020 SPIE.Accession Number: 20210109714323 -
Record 503 of
Title:Large aperture diffractive optical telescope: A review
Author(s):Zhang, Haolin(1,2,3,4); Liu, Hua(1,4); Xu, Wenbin(2); Lu, Zhenwu(2)Source: Optics and Laser Technology Volume: 130 Issue: DOI: 10.1016/j.optlastec.2020.106356 Published: October 2020Abstract:Thanks to the recent development in diffractive optical element (DOE) fabrication technique, large aperture diffractive telescope systems have been tremendously studied to achieve high-resolution imaging. In this review, the universal optical design mechanism of a diffractive telescope system is initially elucidated, and the state-of-art progresses of large aperture diffractive optical telescopes are overviewed. Then, we analyze DOE lithography technique, from which we can fabricate DOEs on different substrates. Moreover, we also present subaperture stitching, so that we can obtain large aperture DOEs. Afterwards, different experimentally implemented ground-based diffractive telescope systems are reviewed by emphasizing their advantages. Finally, we propose the prospects with respect to the arising challenges in large aperture diffractive telescope systems. ? 2020 Elsevier LtdAccession Number: 20202208775165 -
Record 504 of
Title:Mapping diffuse emission in lyman UV band
Author(s):Ji, Li(1,12); Lou, Zheng(1); Zhang, Jinlong(2); Qiu, Keqiang(3); Li, Shuangying(2); Sun, Wei(1,12); Yan, Shuping(1,12); Shuinai, Zhang(1,12); Qian, Yuan(1); Wang, Sen(4); Werner, Klaus(5); Fang, Taotao(6); Wang, Tinggui(7); Barnstedt, Jürgen(5); Buntrock, Sebastian(5); Cai, Mingsheng(1,12); Chen, Wen(8); Conti, Lauro(5); Deng, Lei(8); Diebold, Sebastian(5); Fu, Shaojun(3); Guo, Jianhua(1,12); Hanke, Lars(5); Hong, Yilin(3); Kalkuhl, Christoph(5); Kappelmann, Norbert(5); Kaufmann, Thomas(5); Lei, Shijun(1,12); Li, Fu(9); Li, Xinfeng(10); Liu, Wei(1); Meyer, Kevin(11); Rauch, Thomas(5); Ruan, Ping(9); Schaadt, Daniel M.(11); Schanz, Thomas(5); Song, Qian(4); Stelzer, Beate(5); Wang, Zhanshan(2); Yang, Jianfeng(9); Zhang, Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11444 Issue: DOI: 10.1117/12.2561839 Published: 2020Abstract:The CAFE (Census of warm-hot intergalactic medium, Accretion, and Feedback Explorer) and LyRIC (Lyman UV Radiation from Interstellar medium and Circum-galactic medium) have been proposed to the space agencies in China respectively. CAFE was first proposed in 2015 as a joint scientific CAS-ESA small space mission. LyRIC was proposed in 2019 as an independent external payload operating on the Chinese Space Station. Both missions are dedicated to mapping the Lyman UV emission (ionized oxygen (O vi) resonance lines at 103.2 and 103.8 nm, and Lyman series) for the diffuse sources in our Galaxy and the circum-galactic mediums of the nearby galaxies. We present the primary science objectives, mission concepts, the enabling technologies, as well as the current status. ? 2020 SPIEAccession Number: 20210309778675