2020
2020
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Record 421 of
Title:Perfect soliton crystal in a microcavity via sub-harmonic phase-modulation scheme
Author(s):Lu, Zhizhou(1); Lu, Zhizhou(2); Wang, Yang(1); Wang, Yang(2); Zhao, Bailing(1); Zhao, Bailing(2); Liu, Mulong(1); Liu, Mulong(2); Wang, Weiqiang(1)Source: Japanese Journal of Applied Physics Volume: 59 Issue: 6 DOI: 10.35848/1347-4065/ab91ce Published: July 2020Abstract:We numerically investigate perfect soliton crystal (PSC) generation in a sub-harmonic phase-modulated light pumped microcavity. Parts of the modulated pump frequency components are coupled into the microcavity through the Vernier effect between the modulated pump and cavity modes, which forms a chirped and periodic background wave for soliton formation. With improved pump efficiency, PSCs with 5-20 solitons are demonstrated in a microcavity featuring ～10 GHz free spectral range. It is further found that the modulator can be removed to decrease the pump power while maintaining PSC state. Our work enriches the dynamics and applications of cavity solitons. ? 2020 The Japan Society of Applied Physics.Accession Number: 20202808917791 -
Record 422 of
Title:Fractional quantum couplers
Author(s):Zeng, Liangwei(1,2); Zeng, Jianhua(1,2)Source: Chaos, Solitons and Fractals Volume: 140 Issue: DOI: 10.1016/j.chaos.2020.110271 Published: November 2020Abstract:Fractional quantum coupler, a new type of quantum couplers that is composed of arrays of two coupled waveguides or a dual-core waveguide with intermodal coupling, within which the light waves diffraction is of the fractional-order differentiation, is put forward in the territory of fractional quantum mechanics. The modelling equations of such fractional couplers are derived in the framework of coupled nonlinear fractional Schr?dinger equations with the space derivative of fractional order denoted by Lévy index α, and localized wave solutions as spatial optical solitons of these equations are constructed and their nonlinear propagation properties are discussed. Linear perturbation method based on linear stability analysis, and direct simulations are conducted to identify the stability and instability regions of the predicted solitons. ? 2020 Elsevier LtdAccession Number: 20204109318659 -
Record 423 of
Title:High-Performance Microring Resonator Ge-on-Si Photodetectors by Optimizing Absorption Layer Length
Author(s):Cui, Jishi(1); Li, Tiantian(2); Chen, Hongmin(1); Cui, Wenjing(1)Source: IEEE Photonics Journal Volume: 12 Issue: 4 DOI: 10.1109/JPHOT.2020.3010502 Published: August 2020Abstract:We studied the relationship between the absorption layer length and the performance of Ge-on-Si microring resonator photodetectors. The principle of optimizing the absorption layer length based on the light field distribution was proposed. In the Ge-on-Si photodetectors, the transmission light field is alternately distributed among the germanium absorption layer and the silicon waveguide layer, and gradually absorbed by the germanium layer. For the Ge-on-Si microring resonator photodetectors, the length of the germanium absorption layer should be set to achieve the maximum light field distribution in the silicon layer at the end of the photodetector, then the remaining optical power can be coupled back to the silicon waveguide and transmit in the microring for absorption again. We demonstrated by simulation that, the device with optimized length of 11 μm has larger bandwidth, smaller dark current, and higher responsivity than the device with 14 μm absorption layer by simulation @1550nm. ? 2009-2012 IEEE.Accession Number: 20203409089929 -
Record 424 of
Title:Spatial attention based visual semantic learning for action recognition in still images
Author(s):Zheng, Yunpeng(1,2); Zheng, Xiangtao(1); Lu, Xiaoqiang(1); Wu, Siyuan(1)Source: Neurocomputing Volume: 413 Issue: DOI: 10.1016/j.neucom.2020.07.016 Published: 6 November 2020Abstract:Visual semantic parts play crucial roles in still image-based action recognition. A majority of existing methods require additional manual annotations such as human bounding boxes and predefined body parts besides action labels to learn action related visual semantic parts. However, labeling these manual annotations is rather time-consuming and labor-intensive. Moreover, not all manual annotations are effective when recognizing a specific action. Some of them can be irrelevant and even misguided. To address these limitations, this paper proposes a multi-stage deep learning method called Spatial Attention based Action Mask Networks (SAAM-Nets). The proposed method does not need any additional annotations besides action labels to obtain action-specific visual semantic parts. Instead, we propose a spatial attention layer injected in a convolutional neural network to create a specific action mask for each image with only action labels. Moreover, based on the action mask, we propose a region selection strategy to generate a semantic bounding box containing action-specific semantic parts. Furthermore, to effectively combine the information of the whole scene and the sematic box, two feature attention layers are adopted to obtain more discriminative representations. Experiments on four benchmark datasets have demonstrated that the proposed method can achieve promising performance compared with state-of-the-art methods. ? 2020 Elsevier B.V.Accession Number: 20203108995324 -
Record 425 of
Title:Cobalt and iron co-doped ZnSe nanocrystals:Mid-IR luminescence at room temperature
Author(s):Shi, Huawei(1,2); Cui, Xiaoxia(1,2); Xiao, Xusheng(1,2); Xu, Yantao(1,2); Liu, Chao(3); Hou, Chaoqi(1,2); Guo, Haitao(1,2,4)Source: Journal of Luminescence Volume: 221 Issue: DOI: 10.1016/j.jlumin.2020.117102 Published: May 2020Abstract:Fe:Co:ZnSe nanocrystals with different co-doping ratios of Fe2+/Co2+ ions were fabricated by hydrothermal synthesis. The facile method used in the present work avoids the mid-infrared quench effect induced by the organic molecular introduced in the past preparation process. These nanocrystals are spherical in shape and exhibit a cubic sphalerite structure with an average grain size of about 15 nm. Through the energy conversion between Co2+ and Fe2+ ions, mid-infrared fluorescences at 3.3 μm and 4.4 μm were detected under 1550 nm laser excitation at room temperature. The fluorescence band of 4.4 μm in the Fe:Co:ZnSe nanocrystals is thought to be an overlapping emission involving the peak centered at 4648 nm corresponding to the Co2+:4T1 (F) → 4T2 (F) energy transition and the peak centered at 4273 nm corresponding to Fe2+:5T2 (D) → 5E (D) energy transition. These high-quality optically active nanomaterials show potential applications in mid-infrared devices such as composite fiber-amplifiers and lasers materials. ? 2020Accession Number: 20200708165146 -
Record 426 of
Title:Resonant degenerate four-wave mixing in SO2
Author(s):Wei, W.(1,2); Lu, Z.Z.(1,3); Dong, Q.(3); Sun, Y.L.(3); Ma, L.(3); Liao, J.L.(3); Liu, J.F.(3); Xie, X.P.(1); Zhao, W.(1)Source: Acta Physica Polonica A Volume: 137 Issue: 6 DOI: 10.12693/APhysPolA.137.1022 Published: June 2020Abstract:We report an experimental investigation of degenerate four-wave mixing spectrum of SO2. A novel beam-split technique is used to compensate the beam drift caused by the laser itself and disturbance from the environment. Degenerate four-wave mixing spectra of the transition B1B1 ← X1A11 for SO2 are obtained. The degenerate four-wave mixing signal intensity as a function of the total input laser energy is measured. The effects of the laser field intensity on the degenerate four-wave mixing spectrum are analyzed. Our results show that the degenerate four-wave mixing signal intensity rises with laser intensity and tends to saturate. Then, a dip begins to appear at resonance in the profile with increase in laser field. The existence of saturation for degenerate four-wave mixing signal intensity and spectrum profile confirms the prediction of previous theoretical work. ? 2020 Polish Academy of Sciences. All rights reserved.Accession Number: 20203609132431 -
Record 427 of
Title:Monogamy relations within quadripartite Einstein-Podolsky-Rosen steering based on cascaded four-wave mixing processes
Author(s):Xiang, Yu(1,2,3); Liu, Yang(4,5,6); Cai, Yin(4); Li, Feng(4); Zhang, Yanpeng(4); He, Qiongyi(1,2,3)Source: Physical Review A Volume: 101 Issue: 5 DOI: 10.1103/PhysRevA.101.053834 Published: May 2020Abstract:Multipartite Einstein-Podolsky-Rosen (EPR) steering has been recognized as an essential resource for secure quantum communication tasks composed of several spatially separated parties who cannot be fully trusted. Nevertheless, this resource cannot be distributed arbitrarily over many parties; for instance, two independent players cannot simultaneously steer the third party by two-setting measurements. This feature is referred to as monogamy of steering, which ensures the security of quantum cryptographic protocols and is thus a very desired property to investigate for multipartite steering. Here, we propose symmetric and asymmetric structures of cascaded four-wave mixing of rubidium atoms to generate versatile quadripartite EPR steering and investigate four distinct types of monogamy relations of Gaussian steering. We find that the distribution constraint described by one of the monogamy relations can be lifted only for the quadripartite steering created by the symmetric setup. This result paves the way for a better understanding of the distribution rules of multipartite EPR steering and its potential applications for secure quantum communication. ? 2020 American Physical Society.Accession Number: 20202308792090 -
Record 428 of
Title:Study on the properties of optical microfluidic tunable gradient refractive lens
Author(s):Li, Dongdong(1); Lv, Di(1); Han, Dongdong(1); Liang, Meng(1); She, Jiangbo(2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 49 Issue: 1 DOI: 10.3788/IRLA202049.0116002 Published: January 25, 2020Abstract:Based on convection-diffusion effect, a fluid lens with optical gradient refractive index microcavity was established by using finite element method. The stable concentration distribution of the core and cladding liquid after convenction-diffusion process was analyzed, which was called refractive index distribution of mixed fluid. The structure of convection-diffusion model was studied. For gradient refraction index characteristics of optical microfluidic tunable lens, the effects of different cross-sections on the stability of refractive index distribution along the direction of fluid flow direction were studied respectively in general (the refractive index of core fluid was larger than that of cladding fluid) and in the case of central depression (the refractive index of core fluid was smaller than that of cladding fluid). ? 2020, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.Accession Number: 20201508382519 -
Record 429 of
Title:Near-infrared Photodetection in Graphene/β-InSeHeterostructure
Author(s):Shao, Wen(1); Xie, Xiaoping(1); Zheng, Yunqiang(2); Wang, Wei(2); Li, Tiantian(3); Wang, Feifan(3); Wang, Yong(3); Law, Stephanie(3); Gu, Tingyi(3)Source: 2020 Asia Communications and Photonics Conference, ACP 2020 and International Conference on Information Photonics and Optical Communications, IPOC 2020 - Proceedings Volume: Issue: DOI: null Published: October 2020Abstract:Photoresponsivity of 1.17 A/W is observed in graphene/molecular beam epitaxy grown ?-state In2Se3 photodetector at 1550 nm light excitation and 0.35 V bias, with smaller than 2 ms response time. ? 2020 The Author(s)Accession Number: 20211210116326 -
Record 430 of
Title:5 Gbaud QPSK coherent transmission in the mid-infrared
Author(s):Wang, Wei(1,2); Zheng, Yunqiang(1); Xie, Xiaoping(1,2); Su, Yulong(1,2); Huang, Xinning(1,2); Duan, Tao(1); Zhao, Wei(1,2)Source: Optics Communications Volume: 466 Issue: DOI: 10.1016/j.optcom.2020.125681 Published: 1 July 2020Abstract:We experimentally demonstrate a high-speed mid-infrared (MIR) transmission system with a 5 Gbaud quadrature phase shift keying (QPSK) modulation over free space optical (FSO) link. The MIR system operates through homemade robust and compact MIR transmitter and receiver devices, which has the ability to achieve wavelength conversion between C-band and MIR based on difference frequency generation (DFG) process. The wavelength and power of MIR signal generated from MIR transmitter are 3.57 dBm and 3594 nm, and the C-band signal regenerated from MIR receiver are ?26.12 dBm and 1550.116 nm. Both the constellation diagrams and eye diagrams of regenerated C-band signal are clear when the input power of C-band receiver is higher than ?40 dBm. Compared with the back to back (BTB) transmission system, the power penalty of the MIR transmission system is less than 2.8 dB measured at bit error ratio (BER) of 1×10?7. It can be concluded from the experimental results that the MIR transmission system supports high-speed data rate, variable wavelength and high-order modulation format, and has the potential to be applied to FSO communications or satellite communications in atmospheric environments. ? 2020 Elsevier B.V.Accession Number: 20201108289947 -
Record 431 of
Title:High Quality, Mass-Producible Semipolar GaN and InGaN Light-Emitting Diodes Grown on Sapphire
Author(s):Song, Jie(1,2); Han, Jung(1)Source: Physica Status Solidi (B) Basic Research Volume: 257 Issue: 4 DOI: 10.1002/pssb.201900565 Published: April 1, 2020Abstract:The heteroepitaxy efforts to grow semipolar and nonpolar GaN on foreign substrates of the past 20 years are reviewed and summarized. With the demonstration of three representative semipolar GaN grown on sapphire, the capability to produce semipolar GaN with any orientation on sapphire is exhibited. Also, a unique growth technology called facet-engineered orientation-controlling growth to eliminate the stacking faults (SFs) in semipolar GaN is developed and SF-free (20 (Formula presented.) 1) GaN grown on sapphire is presented, demonstrating the capability of producing device-quality, large-area semipolar GaN. InGaN green light-emitting diodes (LEDs) grown on the SF-free semipolar (20 (Formula presented.) 1) GaN/sapphire templates are performed with much higher external quantum efficiency in comparison with the typical semipolar/nonpolar LEDs heteroepitaxially grown on foreign substrates reported before. ? 2019 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimAccession Number: 20195207901383 -
Record 432 of
Title:Research Status and Development of Graded-index Multi-mode Fiber Mode-locking Technique (Invited)
Author(s):Wang, Yi-Shan(1); Zhao, Feng-Yan(2); Wang, Hu-Shan(1); Hu, Xiao-Hong(1); Zhang, Wei(1); Zhang, Ting(1); Feng, Ye(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 49 Issue: 11 DOI: 10.3788/gzxb20204911.1149003 Published: November 2020Abstract:This paper reviews the research status of the mechanism and technology of all-fiber mode-locked laser ultrashort pulses and bound state soliton generation based on graded index multimode fiber saturable absorber. Using this noval type of all-fiber structured mode-locking modulation device, the output the single pulse energy of conventional soliton in fiber laser can up to the order of nJ, meanwhile spatial mode-locking operation can be realized. As the all-fiber nonlinear saturable absorber, the graded index multimode fiber has important research significance and wide application in lasers, and provides an important technical approach for the generation of higher energy ultrashort pulses. ? 2020, Science Press. All right reserved.Accession Number: 20205109633104