2020
2020
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Record 97 of
Title:Analysis of influence factors of surface defects detection on optical components
Author(s):Deng, Mingjie(1,2,3); Shi, Feng(1,2,3); Sun, Guoyan(4); Xue, Shuai(1,2,3); Tie, Guipeng(1,2,3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11567 Issue: DOI: 10.1117/12.2572696 Published: 2020Abstract:Most of the existing defect detectors focus on the size, location, depth and number of defects of the tested components. The instrument is usually large in size and requires high accuracy for the environment and motion devices. In contrast, the direct random bed motion, which aims at finding and locating defects, is highly efficient, low-cost and environmentally practical, while the research on vibration-resistant defect tester is rare.In order to solve this problem, based on the principle of micro-scattering imaging in dark field, a set of optical component surface defect detection device is built, and the influence factors of light intensity, illumination angle, wavelength and other defect detection factors are experimentally studied, in order to provide design basis for the follow-up development of on-line defect detection instrument. The experimental results show that the most important factor affecting the sensitivity is the azimuth angle and pitch angle of the incident light, which is more than 30 degrees between the incident light and the scratch direction. When the pitch angle is between 60 degrees and 70 degrees, the higher detection sensitivity can be obtained. In addition, improving the illumination intensity can help to improve the detection of defects. In the visible range, the wavelength has little effect on the sensitivity. ? 2020 SPIE.Accession Number: 20205009602530 -
Record 98 of
Title:Giant optical activity in plasmonic chiral structure via double-layer graphene moiré stacking in mid-infrared region
Author(s):Chi, Jiao(1,2); Liu, Hongjun(1,3); Wang, Zhaolu(1); Huang, Nan(1)Source: Optics Express Volume: 28 Issue: 4 DOI: 10.1364/OE.385450 Published: February 17, 2020Abstract:The plasmonic metamaterials and metasurfaces play a critical role in manipulating lights in the mid-infrared spectral region. Here, we first propose a novel plasmonic chiral structure with the giant optical activity in the mid-infrared spectral region. The chiral structure consists of the moiré patterns, which are formed by stacking double-layer graphene nanoribbons with a relative in-plane rotation angle. It is demonstrated that the graphene-based plasmonic structure with moiré patterns exhibits the strong circular dichroism. The giant chiroptical response can be precisely controlled by changing the rotation angle and Fermi level of graphene. Furthermore, a dielectric interlayer is inserted between two layers of graphene to obtain the stronger circular dichroism. Impressively, the strongest circular dichroism can reach 5.94 deg at 13.6 μm when the thickness of dielectric interlayer is 20 nm. The proposed structure with graphene-based moiré patterns can be superior to conventional graphene chiral metamaterials due to some advantage of rotation-dependent chirality, flexible tunability and cost-effective fabrication. It will advance many essential mid-infrared applications, such as chiral sensors, thermal imaging and chiroptical detectors. ? 2020 Optical Society of America.Accession Number: 20200708183140 -
Record 99 of
Title:Speed-up coherent Ising machine with a squeezed feedback system
Author(s):Luo, Lihaonan(1,3); Liu, Hongjun(1,2); Huang, Nan(1); Wang, Zhaolu(1)Source: Optics Express Volume: 28 Issue: 2 DOI: 10.1364/OE.381850 Published: January 20, 2020Abstract:As a solver for non-deterministic polynomial time (NP)-hard combinatorial optimization problems, the coherent Ising machine (CIM) is in the early stages of research, and the potential of this innovative physical system will be developed. Here, we propose a speed-up coherent Ising machine with a squeezed feedback system, which we call S-CIM. We couple squeezed feedback pulses generated by the squeezed feedback system into the degenerate optical parametric oscillator (DOPO) network. Simulations indicate that quantum inseparability of the coupled DOPO network is further enhanced during the whole optimization process, and quantum fluctuations are significantly smaller around the oscillation threshold. Computation experiments are performed on MAX-CUT problems of order between 4 and 20000. Numerical results demonstrate that S-CIM increases the optimal normalized output by 2.27% and significantly reduces the optimal computation time by 75.12%. ? 2020 Optical Society of America under the terms of the OSA Open Access Publishing AgreementAccession Number: 20200408068975 -
Record 100 of
Title:Asymmetric localization and symmetric diffraction-free transmission in synthetic photonic lattice with anti-parity-time symmetry
Author(s):Dai, Yanan(1,2); Wen, Zengrun(1,2); Ji, Kaiwen(1,2); Liu, Zhenjuan(1,2); Wang, Haohao(1,2); Zhang, Zhiqing(1,2); Gao, Yuanmei(4); Lu, Baole(2); Wang, Yishan(3); Qi, Xinyuan(1,2); Bai, Jintao(2)Source: Optics Letters Volume: 45 Issue: 11 DOI: 10.1364/OL.392436 Published: June 1, 2020Abstract:We study, to the best of our knowledge, the first observations of light propagation in synthetic photonic lattice with anti-parity-time symmetry by tuning the gain or loss of two coupled fiber rings alternatively and corresponding phase distribution periodically. By tuning the phase and the wave number Q in the lattice, asymmetric transmission of the light field can be achieved for both long and short loops when 6= nπ/2 (n is an integer). Further investigations demonstrate that asymmetric localization of the light field in the long loop and symmetric diffraction-free transmission in two loops can both be realized by changing these two parameters. Our work provides a new method to obtain anti-parity-time symmetry in synthetic photonic lattice and paves a broad way to achieve novel optical manipulation in photonic devices. ? 2020 Optical Society of AmericaAccession Number: 20202508854619 -
Record 101 of
Title:Longitudinal forced convection heat transfer for high power slab laser media
Author(s):He, Jianguo(1,2,3); Li, Ming(4); Mo, Zeqiang(1,2,3); Wang, Jinduo(1,2); Yu, Jin(1,2); Dai, Shoujun(1,2); Chen, Yanzhong(1); Ge, Wenqi(1); Liu, Yang(1,3); Fan, Lianwen(5)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 49 Issue: 9 DOI: 10.3788/IRLA20200556 Published: September 25, 2020Abstract:Thermal problem becomes more prominent in the highly-pumped laser gain mediums, for which, the forced convective heat transfer with the advantages of reliability and durability is widely used. However, a flow direction induced temperature gradient always appears within the laser operating substance during the convective heat transfer. Subsequently, it is significantly responsible for the detrimental thermal stress which mainly cause the wave front distortion. Herein, considering the idea of temperature matching between flow field and the operating substance, a cooling configuration for double face pumped slab crystal based on longitudinal forced convective heat transfer was presented, which showed a more efficient cooling and achieved a most homogeneous temperature distribution within the crystal. The influences of flow rate, state of flow field and surface roughness were systematically studied that a fully developed flow state, higher flow rate and rougher surface lead to an improvement in cooling capability. In the simulation with 30 L/min flow rate, the calculated convective heat transfer coefficient was as high as 104 W·m?2·K?1, and even higher when a more coarse surface was implemented. Furthermore, a module based on the configuration was fabricated and the experimental results agree well with the simulation, which shows a good temperature distribution and very weak thermal lensing is achieved. Copyright ?2020 Infrared and Laser Engineering. All rights reserved.Accession Number: 20204309403524 -
Record 102 of
Title:Material removal behaviour in axial ultrasonic assisted scratching of Zerodur and ULE with a Vickers indenter
Author(s):Sun, Guoyan(1,2); Shi, Feng(1); Zhao, Qingliang(3); Ma, Zhen(2); Yang, Donglai(2)Source: Ceramics International Volume: 46 Issue: 10 DOI: 10.1016/j.ceramint.2020.02.262 Published: July 2020Abstract:Compared to conventional grinding, axial ultrasonic vibration-assisted peripheral grinding (AUPG) has advantages in terms of the improved grinding quality, higher efficiency, as well as lowered brittle damages. However, the present studies on material removal mechanism of AUPG are still not sufficient which thereafter limit its application potential. This paper aims to investigate the material removal mechanism of Zerodur and ULE through scratching by using a Vickers indenter under two conditions, with (ultrasonic vibration-assisted scratching (UVS)) and without (conventional scratching (CS)) axial ultrasonic vibration-assisted scratching while the other scratching parameters are identical. The indenter's kinematic characteristic, scratched morphology, scratched groove dimensions and critical depth of cut are compared in between UVS and CS. The experimental results indicate that the dynamic contact length between indenter and workpiece for UVS is remarkable longer than that for CS, which is helpful to promote the crack interference and hence to increase the proportion of ductile material removal mode, resulting in the diminishment of brittle fracture size in UVS. The propagation direction of median cracks in CS are relatively consistent, while in UVS the periodic varied contact zone and contact force in between the indenter and workpiece could promote the cracks propagating in different orientations, and then to improve the material removals rate in UVS. Moreover, both the critical brittle-ductile transition depth of cut and critical brittle depth of cut in UVS are bigger than that in CS, meaning the material removed in UVS with a bigger ductile ratio leading to a decreased brittle damage depth. In addition, the different material removal behaviours between Zerodur and ULE are also investigated. This fundamental work lays a theoretical foundation for the technological development and broad application of hard/brittle material oriented AUPG, as well as poses a meaningful guidance for the ultrasonic vibration assisted grinding on low-expansion optical glasses. ? 2020 Elsevier Ltd and Techna Group S.r.l.Accession Number: 20201108280077 -
Record 103 of
Title:A General-Purpose Dehazing Algorithm based on Local Contrast Enhancement Approaches
Author(s):Sun, Bangyong(1,2); Whannou de Dravo, Vincent(1); Yu, Zhe(1)Source: arXiv Volume: Issue: DOI: null Published: May 31, 2020Abstract:Dehazing is in the image processing and computer vision communities, the task of enhancing the image taken in foggy conditions. To better understand this type of algorithm, we present in this document a dehazing method which is suitable for several local contrast adjustment algorithms. We base it on two filters. The first filter is built with a step of normalization with some other statistical tricks while the last represents the local contrast improvement algorithm. Thus, it can work on both CPU and GPU for real-time applications. We hope that our approach will open the door to new ideas in the community. Other advantages of our method are first that it does not need to be trained, then it does not need additional optimization processing. Furthermore, it can be used as a pre-treatment or post-processing step in many vision tasks. In addition, that it does not need to convert the problem into a physical interpretation, and finally that it is very fast. This family of defogging algorithms is fairly simple, but it shows promising results compared to state-of-the-art algorithms based not only on a visual assessment but also on objective criteria. . . . Copyright ? 2020, The Authors. All rights reserved.Accession Number: 20200396048 -
Record 104 of
Title:Induced Photon Correlations Through the Overlap of Two Four-Wave Mixing Processes in Integrated Cavities
Author(s):Zhang, Yanbing(1); Kues, Michael(2,3); Roztocki, Piotr(1); Reimer, Christian(1,4); Fischer, Bennet(1); MacLellan, Benjamin(1); Bisianov, Arstan(5); Peschel, Ulf(5); Little, Brent E.(6); Chu, Sai T.(7); Moss, David J.(8); Caspani, Lucia(9); Morandotti, Roberto(1,10)Source: Laser and Photonics Reviews Volume: 14 Issue: 9 DOI: 10.1002/lpor.202000128 Published: September 1, 2020Abstract:Induced photon correlations are directly demonstrated by exploring two coupled nonlinear processes in an integrated device. Using orthogonally polarized modes within an integrated microring cavity, phase matching of two different nonlinear four-wave mixing processes is achieved simultaneously, wherein both processes share one target frequency mode, while their other frequency modes differ. The overlap of these modes leads to the coupling of both nonlinear processes, producing photon correlations. The nature of this process is confirmed by means of time- and power-dependent photon correlation measurements. These findings are relevant to the fundamental understanding of spontaneous parametric effects as well as single-photon-induced processes, and their effect on optical quantum state generation and control. ? 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimAccession Number: 20203008964215 -
Record 105 of
Title:Simulation of magnetic field effects on the MCP gain
Author(s):Li, L.(1,2); Guo, L.(1,2); Wei, Y.(1,2); Sai, X.(1,2); Liu, H.(1,2); He, K.(1,2); Gou, Y.(1,2); Liu, B.(1,2); Tian, J.(1,2,3); Chen, P.(1,2,3)Source: Journal of Instrumentation Volume: 15 Issue: 3 DOI: 10.1088/1748-0221/15/03/C03048 Published: March 2020Abstract:A multi-anode microchannel plate photomultiplier (Ma MCP-PMT) is an appropriate photo sensor for particle identification in high energy physics experiments such as PANDA, Belle II, etc. Since these detectors usually work in a strong magnetic field, the sensors must be immune to the field. In this article, the effects of the magnetic field on the conventional MCP and the atomic layer deposited MCP (ALD-MCP) are studied by simulating the electron multiplication in the microchannel of the MCP . Simulation results show that the gain of conventional MCP-PMTs increases a little before it starts decreasing while the magnetic field is further increasing. We found that the shortening of electronic trajectories and the reduction of secondary electrons mainly contribute to gain variations of a conventional MCP . For the ALD-MCP that usually has higher secondary emission yields, it is found that high re-diffusion secondary electron yields could make it more vulnerable to magnetic fields. ? 2020 IOP Publishing Ltd and Sissa Medialab.Accession Number: 20201908615940 -
Record 106 of
Title:2D Layered Graphene Oxide Films Integrated with Micro-Ring Resonators for Enhanced Nonlinear Optics
Author(s):Wu, Jiayang(1); Yang, Yunyi(1,2); Qu, Yang(1); Jia, Linnan(1); Zhang, Yuning(1); Xu, Xingyuan(1); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5); Jia, Baohua(1,2); Moss, David J.(1)Source: Small Volume: 16 Issue: 16 DOI: 10.1002/smll.201906563 Published: April 1, 2020Abstract:Layered 2D graphene oxide (GO) films are integrated with micro-ring resonators (MRRs) to experimentally demonstrate enhanced nonlinear optics. Both uniformly coated (1?5 layers) and patterned (10?50 layers) GO films are integrated on complementary-metal-oxide-semiconductor (CMOS)-compatible doped silica MRRs using a large-area, transfer-free, layer-by-layer GO coating method with precise control of the film thickness. The patterned devices further employ photolithography and lift-off processes to enable precise control of the film placement and coating length. Four-wave-mixing (FWM) measurements for different pump powers and resonant wavelengths show a significant improvement in efficiency of ≈7.6 dB for a uniformly coated device with 1 GO layer and ≈10.3 dB for a patterned device with 50 GO layers. The measurements agree well with theory, with the enhancement in FWM efficiency resulting from the high Kerr nonlinearity and low loss of the GO films combined with the strong light–matter interaction within the MRRs. The dependence of GO's third-order nonlinearity on layer number and pump power is also extracted from the FWM measurements, revealing interesting physical insights about the evolution of the GO films from 2D monolayers to quasi bulk-like behavior. These results confirm the high nonlinear optical performance of integrated photonic resonators incorporated with 2D layered GO films. ? 2020 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimAccession Number: 20201108301169 -
Record 107 of
Title:Generation of sub-7 fs radially polarized pulses by thin plate post-compression
Author(s):Cao, H.(1,2); Nagymihaly, R.S.(1); Khodakovskiy, N.(1); Lopez-Martens, R.(1,3); Pajer, V.(1); Bohus, J.(1); Bussiere, B.(4); Falcoz, F.(4); Borzsonyi, A.(1); Kalashnikov, M.(1)Source: Optics InfoBase Conference Papers Volume: Issue: DOI: null Published: October 13, 2020Abstract:Post-compression of radially polarized 30 fs pulses was performed in multiple thin fused silica plates for the first time. Sub-7 fs pulses with 90 μJ were obtained after re-compression. This approach is scalable in energy. ? 2020 The Author(s)Accession Number: 20211210099322 -
Record 108 of
Title:Optical trapping of single nano-size particles using a plasmonic nanocavity
Author(s):Zhang, Jiachen(1); Lu, Fanfan(1); Zhang, Wending(1); Yu, Weixing(2); Zhu, Weiren(3); Premaratne, Malin(4); Mei, Ting(1); Xiao, Fajun(1,2); Zhao, Jianlin(1)Source: Journal of Physics Condensed Matter Volume: 32 Issue: 47 DOI: 10.1088/1361-648X/abaead Published: November 11, 2020Abstract:Trapping and manipulating micro-size particles using optical tweezers has contributed to many breakthroughs in biology, materials science, and colloidal physics. However, it remains challenging to extend this technique to a few nanometers particles owing to the diffraction limit and the considerable Brownian motion of trapped nanoparticles. In this work, a nanometric optical tweezer is proposed by using a plasmonic nanocavity composed of the closely spaced silver coated fiber tip and gold film. It is found that the radial vector mode can produce a nano-sized near field with the electric-field intensity enhancement factor over 103 through exciting the plasmon gap mode in the nanocavity. By employing the Maxwell stress tensor formalism, we theoretically demonstrate that this nano-sized near field results in a sharp quasi-harmonic potential well, capable of stably trapping 2 nm quantum dots beneath the tip apex with the laser power as low as 3.7 mW. Further analysis reveals that our nanotweezers can stably work in a wide range of particle-to-tip distances, gap sizes, and operation wavelengths. We envision that our proposed nanometric optical tweezers could be compatible with the tip-enhanced Raman spectroscopy to allow simultaneously manipulating and characterizing single nanoparticles as well as nanoparticle interactions with high sensitivity. ? 2020 IOP Publishing Ltd.Accession Number: 20204109315351