2019

• Record 433 of
  
  Title:Analysis of Cryogenic Characteristics of High Power Semiconductor Lasers
  
  Author(s):Wang, Ming-Pei(1,2); Zhang, Pu(1); Nie, Zhi-Qiang(1); Liu, Hui(3); Sun, Yu-Bo(1,2); Wu, Di-Hai(1,2); Zhao, Yu-Liang(1,2)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 48  Issue: 9  DOI: 10.3788/gzxb20194809.0914002  Published: September 1, 2019  
  Abstract:A set of cryogenic measurement system for semiconductor lasers with micro-channel structure was developed. The stable measurement of some vital parameters such as output power, electro-optic conversion efficiency and spectra of high power semiconductor lasers in the range from -60℃ to 0℃ were realized. Based on computational fluid dynamics and numerical heat transfer methods, the heat dissipation performance of three cryogenic coolants, anhydrous ethanol, trichloroethylene and pentafluoropropane was simulated. The simulation results show that semiconductor laser bar with anhydrous ethanol as the coolant has the smallest thermal resistance(0.73 K/W) and the best temperature uniformity(temperature difference between emitters is 1.45℃) when the pressure drop is 0.47 bar. Anhydrous ethanol was used as system coolant, the maximum of ethanol flow rate was up to 0.5 L/min, and 5 semiconductor laser bars could work simultaneously in the system. Based on the cryogenic measurement system, the cryogenic characteristics of 976 nm semiconductor laser bar with micro-channel structure at 6% duty cycle were investigated. The experimental results show that the output power of semiconductor laser bar is increased from 388.37 W to 458. 37 W which the power-up ratio is 18.02%, the electro-optic conversion efficiency is increased from 60.99% to 67.25%, the efficiency is increased by 6.26%, and the central wavelength is shifted from 969.68 nm to 954.05 nm when the coolant temperature decreases from 0℃ to -60℃. The turn-on voltage increases by 0.04 V, the threshold current decreases by 3.93 A, the series resistance increases by 0.18 mΩ, and the external differential efficiency increases by 11.84%. The analysis shows that the decrease of threshold current and the improvement of external differential efficiency are the main factors that promote the power and efficiency of semiconductor lasers at low temperature. This investigation shows that the cryogenic working mode of liquid micro-channel cooling is an effective means to achieve high output power and high electro-optic conversion efficiency of semiconductor lasers. © 2019, Science Press. All right reserved.
  Accession Number: 20194207539124
• Record 434 of
  
  Title:Effect of Ba(PO3)2 addition on the optical properties of Tm3+-doped fluorophosphate glasses
  
  Author(s):Sun, Xin(1,2); She, Jiangbo(1); Li, Xiaohui(2); Lu, Min(1); Wang, Pengfei(1); Li, Dongdong(3)
  Source: Optical Materials Express  Volume: 9  Issue: 3  DOI: 10.1364/OME.9.001233  Published: 2019  
  Abstract:Tm3+-doped fluorophosphate glasses with varying Ba(PO3)2 content were prepared by the melt quenching technique and their thermal and optical properties were investigated by studying differential scanning calorimetry, Raman spectra, fluorescence spectra, decay curves, transmission and absorption spectra. The Judd-Ofelt theory was applied to calculate the intensity parameters of the resultant glass. The glass forming criterion was obtained to be 146 °C. The gain coefficient and fluorescence lifetime of Tm3+-doped fluorophosphate glass with 20 mol% Ba(PO3)2 were 3.045 × 10-21 cm2 × ms and 0.406 ms, respectively, which are the highest value among the fluorophosphate glasses with similar components to the best of our knowledge. These results clearly indicate that the prepared fluorophosphate glass is an attractive candidate for 2 μm lasers and as a gain media for optical amplifier applications. © 2019 Optical Society of America.
  Accession Number: 20193507380747
• Record 435 of
  
  Title:Optical design of X-ray focusing telescope
  
  Author(s):Qiang, Peng-Fei(1,2); Sheng, Li-Zhi(1); Li, Lin-Sen(1,2); Yan, Yong-Qing(1); Liu, Zhe(1); Zhou, Xiao-Hong(1)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 68  Issue: 16  DOI: 10.7498/aps.68.20190709  Published: August 20, 2019  
  Abstract:X-ray focusing telescope is one of the most important equipment for X-ray space observation, which is designed based on the grazing incidence principle. The purpose of x-ray observation is to detect the black holes of various sizes in outer space, and the data obtained by X-ray telescope conduces to investigating the basic physical law under the condition of extreme gravity and magnetic field, In this article, multi-layer telescope is designed to satisfy the demand for enhanced X-ray timing and polarimetry mission. in which the telescope is designed based on Wolter-I telescope. The Monte Carlo method and power spectral density are used when the relationship between mirror profile and roughness with angular resolution is investigated. We analyze the relationship between angular resolution and mirror profile, and the result shows that the higher mirror profile possesses higher angular resolution. When the root mean square(RMS) of mirror profile is 0.04 μm, PV is 0.2 μm and roughness is 0.4 nm, the mirror angular resolution is 6.3" and it will change to 30.6" when the RMS of mirror profile is 0.2 μm, PV is 1 μm and roughness is 0.4 nm. The angular resolution out of focus is also investigated in this article, and the more defocusing amount gives rise to the worse angular resolution because defocusing spot will be larger than that of focal plane. So the maximum defocusing amount of 5 mm is required when the focal plane detector is installed. The relationship between effective area with film structure and layers number is also investigated. The film with Au mixed with C has a higher reflectivity than the film with only Au, because the mixed film will generate an interference effect and enhance the intensity of reflecting X-ray. When the telescope layers increase, the effective area and telescope weight are both improved, the requirement for effective area of satellite can be satisfied when the number of nesting layers is 45. However, when the number of nesting layers further increase, the effective area will be improved with a low speed, but the weight of telescope will increase with a high speed. The field of view of this telescope is 16', which is more than the required value of 12'. Finally, the X-ray focusing telescope with 5.25 m focal length, 45 nesting layers, effective area 842 cm2 at 2 keV, 563 cm2 at 6 keV is obtained. © 2019 Chinese Physical Society.
  Accession Number: 20194207561378
• Record 436 of
  
  Title:Single photon counting 3D imaging implemented under signal-to-noise ratio less than one
  
  Author(s):Kang, Yan(1); Zhang, Tongyi(1); Li, Lifei(1); Wang, Biao(2); Zhao, Wei(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11209  Issue:   DOI: 10.1117/12.2549971  Published: 2019  
  Abstract:We report a five-step processing algorithm for photon counting depth imaging under strong background noise environment, and experimentally verified that this method can realize single photon counting 3D imaging under signalto-noise ratio (SNR) less than 1. In order to accurately locate the target position when the ambient flux is high, a computational pile-up correction is performed to recover the underlying signal photons, then performing an adaptively full-pixel target position locating. After the target position is determined, the signal and noise photons are separated pixel-wisely using a cluster method. Pixels which have no arrival photons are filled by using the information from neighborhood. At last, by using total variation spatial regularization, the depth images are reconstructed accurately. To validate the proposed method, a single photon counting 3D imaging system is established and experiments at different noise levels are carried out. Experimental results show that accurate depth imaging can be reconstructed with the SNR as low as 0.41. This approach is suitable for depth imaging under high background noise and also very suitable for the noncooperative target imaging with no prior knowledge of the target distance for its adaptive range gating. © 2019 SPIE.
  Accession Number: 20200508093410
• Record 437 of
  
  Title:Research on 940nm kilowatt high efficiency quasi-continuous diode laser bars
  
  Author(s):Zhao, Yuliang(1,2); Wang, Zhenfu(1); Yang, Guowen(1,2); Li, Te(1); Song, Yunfei(1); Qi, Luhan(1); Wang, Gang(1,2); Liu, Yuxian(1,2); Li, Bo(1,2); Bai, Shaobo(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11170  Issue:   DOI: 10.1117/12.2534034  Published: 2019  
  Abstract:High-power GaAs-based semiconductor lasers are the most efficient source of energy for converting electrical into optical power. 940nm diode lasers are used directly or as pump sources for Yb:YAG solid-state lasers, and are widely used in laser cladding and other fields. Improving electro-optic conversion efficiency and reliable output power are urgent requirements for current research hotspots and industrial laser systems. In this paper, we use an asymmetric epitaxial structure of InGaAs/AlGaAs, which reduces the optical loss and resistance, and adopt better cavity surface technology to present 940nm 1-cm quasi-continuous micro-channel cooling (MCC) laser bars. The lasers are tested under a high duty cycle of 9.6% (600us,160Hz) at 25°C with output power of 660.05W, electro-optic conversion efficiency of 64.71% at 600A and slope efficiency of 1.16 W/A. The peak efficiency reaches 72.4%. The increased efficiency results from a lower threshold current and a lower series resistance. Furthermore, the output power of 1025W (1000A) has been confirmed at a duty cycle of 4% (400us,100Hz). © 2019 SPIE.
  Accession Number: 20193107262614
• Record 438 of
  
  Title:Intense terahertz waves generated by three-color laser with different frequency ratios
  
  Author(s):Wang, Hanqi(1,2); Fan, Wenhui(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11209  Issue:   DOI: 10.1117/12.2549974  Published: 2019  
  Abstract:Femtosecond laser-induced air plasma can generate terahertz waves. The sawtooth-like asymmetric photoelectric field can be made by the superposition of three-color laser with appropriate amplitude ratio, frequency ratio and phase difference. Based on the transient photocurrent model and numerical simulation, it is found that intense terahertz waves can be generated by the sawtooth-like asymmetric photoelectric field with different frequency ratios of three-color femtosecond laser, such as 1:2:4 and 1:2:6. By investigating time-varying parameters, such as electron density, electron velocity and photocurrent density, it was further demonstrated that the shape of the asymmetric photoelectric field plays an important role in the formation of net photocurrent and the generation of terahertz waves. The investigation will be helpful to the development of key techniques on intense terahertz waves generated by laser-induced air plasma. © 2019 SPIE.
  Accession Number: 20200508093412
• Record 439 of
  
  Title:Polarization tunable terahertz plasmon induced transparency in graphene ring-rod metamaterial
  
  Author(s):Jiang, Xiao-Qiang(1,2); Wang, Kai(1,2); Fan, Wen-Hui(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11209  Issue:   DOI: 10.1117/12.2550115  Published: 2019  
  Abstract:A periodic two-dimensional metamaterial with plasmon induced transparency effect in terahertz region, composed of polyimide layer covered by a monolayer graphene ring-rod structure, is presented and numerically investigated. The structure shows a remarkable polarization-sensitive transparent window in terahertz band due to the interference phenomenon caused by mode coupling. The results demonstrate that the transparent window of plasmon induced transparency can be flexibly controlled by adjusting the Fermi level of graphene and the polarization angle of incident terahertz wave, which are verified by numerical simulation and dipole-dipole interaction model. Moreover, the maximum group delay time corresponding to the polarization angle at 0 degree is 136.57 fs, exhibiting obvious slow light characteristics. The proposed metamaterial may give rise to practical application in terahertz switches and slow light devices. © 2019 SPIE.
  Accession Number: 20200508093421
• Record 440 of
  
  Title:Helicity-dependent multifunctional light manipulation based on dielectric metasurfaces
  
  Author(s):Li, Xingyi(1,2); Li, Siqi(1,2); Zeng, Chao(1,2); Wang, Guoxi(1,2); Zhang, Wenfu(1,2)
  Source: Optics InfoBase Conference Papers  Volume: Part F138-ACPC 2019  Issue:   DOI: null  Published: 2019  
  Abstract:Metasurfaces have recently emerged to realize flat optical components with various functions. We propose an all-dielectric metasurfaces which can achieve multifunctional light manipulating. Through the combination of the dynamic phase and the Pancharatnam-Berry phase, independent manipulation of orthogonal circular polarization is achieved. Asia Communications and Photonics Conference (ACP) © OSA 2019 © 2019 The Author(s)
  Accession Number: 20202008652905
• Record 441 of
  
  Title:In situ correction of liquid meniscus in cell culture imaging system based on parallel Fourier ptychographic microscopy (96 Eyes)
  
  Author(s):Pan, An(1,2,3); Chan, Antony C.S.(1); Yao, Baoli(2); Yang, Changhuei(1)
  Source: arXiv  Volume:   Issue:   DOI: null  Published: November 28, 2019  
  Abstract:We collaborated with Amgen and spent five years in designing and fabricating next generation multi-well plate imagers based on Fourier ptychographic microscopy (FPM). A 6-well imager (Emsight) and a low-cost parallel microscopic system (96 Eyes) based on parallel FPM were reported in our previous work. However, the effect of liquid meniscus on the image quality is much stronger than anticipated, introducing obvious wavevector misalignment and additional image aberration. To this end, an adaptive wavevector correction (AWC-FPM) algorithm and a pupil recovery improvement strategy are presented to solve these challenges in situ. In addition, dual-channel fluorescence excitation is added to obtain structural information for microbiologists. Experiments are demonstrated to verify their performances. The accuracy of angular resolution with our algorithm is within 0.003 rad. Our algorithms would make the FPM algorithm more robust and practical and can be extended to other FPM-based applications to overcome similar challenges. Copyright © 2019, The Authors. All rights reserved.
  Accession Number: 20200382233
• Record 442 of
  
  Title:Data Denoising Method for Rock Identification Based on LIBS Technology
  
  Author(s):Wang, Chong(1); Zhang, Xiao-Mo(1); Zhu, Xiang-Ping(2,3); Luo, Wen-Feng(1); Shan, Juan(3)
  Source: Guangzi Xuebao/Acta Photonica Sinica  Volume: 48  Issue: 10  DOI: 10.3788/gzxb20194810.1030001  Published: October 1, 2019  
  Abstract:There have been confront with a low identification accuracy problem due to the poor repeatability and high data residual value of laser-induced breakdown spectrum. In order to solve such problems, an distinguishing method of abnormal value based on Grubbs criterion (3δ-Grubbs) was proposed. The method can effectively replace the data of large residual values to reduce the probability of over-fitting in the classification recognition algorithm. Finally, by using three classification recognition algorithms: linear discriminant analysis, random forest classification and support vector machine, we identified the LIBS spectrum of rocks. Before the data noise reduces, the recognition accuracy of the three methods were: linear discriminant analysis 79.6%, random forest classification 75.2%, support vector machine 94.5%.After data noise is reduced, the recognition accuracy of the three methods is as follows: linear discriminant analysis 92%, random forest classification 97%, support vector machine 99.4%. © 2019, Science Press. All right reserved.
  Accession Number: 20194707721042
• Record 443 of
  
  Title:Versatile multipartite Einstein-podolsky-rosen steering via a quantum frequency comb
  
  Author(s):Cai, Yin(1,2); Xiang, Yu(3,4,5); Liu, Yang(1,6,7); He, Qiongyi(3,4,5); Treps, Nicolas(2)
  Source: arXiv  Volume:   Issue:   DOI: null  Published: October 30, 2019  
  Abstract:Multipartite Einstein-Podolsky-Rosen steering is an essential resource for quantum communication networks where the reliability of equipment at all of the nodes cannot be fully trusted. Here, we present experimental generation of a highly versatile and flexible repository of multipartite steering using an optical frequency comb and ultrafast pulse shaping. Simply modulating the optical spectral resolution of the detection system using the pulse shaper, this scheme is able to produce on-demand 4, 8 and 16-mode Gaussian steering without changing the photonics architecture. We find that the steerability increases with higher spectral resolution. For 16-mode state, we identify as many as 65 534 possible bipartition steering existing in this intrinsic multimode quantum resource, and demonstrate that the prepared state steerability is robust to mode losses. Moreover, we verify four types of monogamy relations of Gaussian steering and demonstrate strong violation for one of them. Our method offers a powerful foundation for constructing quantum networks in real-world scenario. Copyright © 2019, The Authors. All rights reserved.
  Accession Number: 20200248550
• Record 444 of
  
  Title:Influence of electro-optical crystal flatness on indirect modulation signal for underwater blue-green laser communication
  
  Author(s):Han, Biao(1,2); Wang, Wei(1); Zheng, Yunqiang(1); K., Shi; J., Meng; Y., Su; T., Wang; Y., Han; X., Xie; W., Zhao
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11068  Issue:   DOI: 10.1117/12.2524680  Published: 2019  
  Abstract:Indirect modulation with electro-optical crystal is a useful way to generate optical signal for underwater blue-green laser communication. However, as crystal surface is not strictly flat in practical application, light intensity distribution in the cross section is non-uniform, which would affect extinction ratio of modulated signal and system performance. In this letter, we study this issue with Monte Carlo method. The result shows that with the increase of crystal flatness, extinction ratio is decreasing dramatically, and it should be smaller than 0.78μm in order to make the extinction ratio greater than 10dB while 0.25μm for 20dB, 0.08μm for 30dB, and 0.025μm for 40dB. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
  Accession Number: 20192106969571