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A new method for extending rate equation based VCSEL model with multimode spectral characteristic

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Science China(Information Sciences) 2018年第12期61卷 155-162页

作者： Anzhong LIANG Chuanchuan YANG Cheng ZHANG Jingjing SONG Hongbin LI State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University

An accurate VCSEL model is important to evaluate the performance of VCSEL-based high speed short range optical interconnect system. Current VCSEL models show no evidence of the multimode spectral characteristic, which leads to an inaccurate performance estimation of VCSEL-based high speed optical interconnect system especially with large chromatic dispersion. To overcome this problem, we propose a new method to introduce multimode spectral characteristic into current VCSEL models, which extends the spatiotemporal multimode rate equations by calculating the wavelength shift of the VCSEL transverse modes. A VCSEL-multimode fiber(MMF) based short range optical interconnect simulation system is then built using our modified VCSEL model by VPItransmissionMaker. The symbol broadening and the BER performance of 15 Gb/s NRZ signal are tested in both left-tilted differential mode delay(DMD) profile MMF(L-MMF) and right-tilted DMD profile MMF(R-MMF). Simulation results validate our proposed method and indicate that the spectral characteristic is a key component for VCSEL models.

关键词： short-range optical interconnect vertical cavity surface emitting lasers VCSEL multimode rate equations multimode spectral characteristic multimode fiber

Perfect anomalous reflectors at optical frequencies

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arXiv 2021年

作者： He, Tao Liu, Tong Xiao, Shiyi Wei, Zeyong Wang, Zhanshan Zhou, Lei Cheng, Xinbin MOE Key Laboratory of Advanced Micro-Structured Materials Shanghai200092 China Institute of Precision Optical Engineering School of Physics Science and Engineering Tongji University Shanghai200092 China Shanghai Institute of Intelligent Science and Technology Tongji University Shanghai200092 China State Key Laboratory of Surface Physics Key Laboratory of Micro and Nano Photonic Structures Ministry of Education Department of Physics Fudan University Shanghai200438 China Key Laboratory of Specialty Fiber Optics and Optical Access Networks Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication Shanghai University Shanghai200444 China

Reflecting light to a pre-determined non-specular direction is an important ability of metasurfaces, which is the basis for a wide range of applications (e.g., beam steering/splitting and imaging). However, anomalous reflection with 100% efficiency has not been achieved at optical frequencies in conventional metasurfaces, due to losses and/or insufficient nonlocal control of light waves. Here, we propose a new type of all-dielectric quasi-three-dimensional subwavelength structures, consisting of multilayer films and specifically designed meta-gratings, to achieve perfect anomalous reflections at optical frequencies. A complex multiple scattering process was stimulated by effectively coupling different Bloch waves and propagating waves in the proposed meta-system, thus offering the whole meta-system the desired nonlocal control on light waves required to achieve perfect anomalous reflections. Two perfect anomalous reflectors were designed to reflect normally incident 1550 nm light to the 40° and 75° directions with absolute efficiencies higher than 99%, and were subsequently fabricated and experimentally demonstrated to exhibit efficiencies 98% and 88%, respectively. Our results pave the way towards realizing optical meta-devices with desired high efficiencies in realistic applications. Copyright © 2021, The Authors. All rights reserved.

关键词： Natural frequencies

Waveguide-integrated twisted bilayer graphene photodetectors (vol 15, 3688, 2024)

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NATURE communicationS 2024年第1期15卷 3688页

作者： Wu, Qinci Qian, Jun Wang, Yuechen Xing, Luwen Wei, Ziyi Gao, Xin Li, Yurui Liu, Zhongfan Liu, Hongtao Shu, Haowen Yin, Jianbo Wang, Xingjun Peng, Hailin Peking University Center for Nanochemistry Beijing Science and Engineering Center for Nanocarbons Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Beijing Graphene Institute Beijing P. R. China (GRID:grid.510905.8) Peking University Center for Nanochemistry Beijing Science and Engineering Center for Nanocarbons Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Beijing Graphene Institute Beijing P. R. China (GRID:grid.510905.8) Peking University Academy for Advanced Interdisciplinary Studies Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Peking University State Key Laboratory of Advanced Optical Communications System and Networks School of Electronics Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Peking University School of Engineering Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Peking University State Key Laboratory of Advanced Optical Communications System and Networks School of Electronics Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Beijing Graphene Institute Beijing P. R. China (GRID:grid.510905.8) Peking University Academy for Advanced Interdisciplinary Studies Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Peking University Center for Nanochemistry Beijing Science and Engineering Center for Nanocarbons Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular Engineering Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Beijing Graphene Institute Beijing P. R. China (GRID:grid.510905.8) Peking University Academy for Advanced Interdisciplinary Studies Beijing P. R. China (GRID:grid.11135.37) (ISNI:0000 0001 2256 9319) Peking University State Key Laboratory of Advanced Optical Com

Graphene photodetectors have exhibited high bandwidth and capability of being integrated with silicon photonics (SiPh), holding promise for future optical communication devices. However, they usually suffer from a low photoresponsivity due to weak optical absorption. In this work, we have implemented SiPh-integrated twisted bilayer graphene (tBLG) detectors and reported a responsivity of 0.65 A W–1 for telecom wavelength 1,550 nm. The high responsivity enables a 3-dB bandwidth of >65 GHz and a high data stream rate of 50 Gbit s–1. Such high responsivity is attributed to the enhanced optical absorption, which is facilitated by van Hove singularities in the band structure of high-mobility tBLG with 4.1o twist angle. The uniform performance of the fabricated photodetector arrays demonstrates a fascinating prospect of large-area tBLG as a material candidate for heterogeneous integration with ***-integrated graphene photodetectors exhibit promising bandwidths at telecom wavelengths, but their responsivity is usually limited. Here, the authors report the wafer-scale fabrication of waveguide-integrated detectors based on twisted bilayer graphene, showing responsivities up to 0.65 A/W and 3-dB bandwidths >65 GHz.

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Generative Adversarial Network-based Channel Modeling for Free-Space optical communication

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Generative Adversarial Network-based Channel Modeling for Fr...

OptoElectronics and communications Conference, OECC

作者： Wenbin Chen Danshi Wang Dongdong Wang Yuchen Song Jin Li Min Zhang State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Science and Technology on Communication Networks Laboratory Shijiazhuang China The 54th Research Institute of China Electronics Technology Group Corporation Shijiazhuang China Purple Mountain Lab Nanjing China

Two deep learning-based differentiable models based on GAN and BiLSTM are proposed for FSO channel modeling. Through contrastive analysis, it shows that GAN is more suitable for learning FSO channel distribution with ... 详细信息

ISBN: (数字)9781943580927

ISBN: (纸本)9781665400060

关键词： Wireless communication Analytical models Free-space optical communication Stochastic processes Generative adversarial networks Channel models

Graphene based all-optical switch and tunable optical filter by using the thermo-optic effect

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Graphene based all-optical switch and tunable optical filter...

7th advanced Electromagnetics Symposium, AES 2019

作者： Qiu, Ciyuan Guo, Tao Wu, Kan State Key Lab of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University China

In this paper, we present our recent works on graphene based integrated devices by using the thermo-optic effect. We demonstrated an all-optical switch with a response time constant of 253.0 ns and a switching energy of ~50 nJ. Furthermore, we implemented a nanobeam based tunable optical filter with a tuning efficiency ~1.5 nm/mW by using a graphene micro-heater. © 2019 advanced Electromagnetics Symposium. All rights reserved.

关键词： Graphene

Bias-free source-independent quantum random number generator

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arXiv 2020年

作者： Zheng, Ziyong Zhang, Yichen Huang, Min Chen, Ziyang Yu, Song Guo, Hong State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing100876 China State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronics Center for Quantum Information Technology Peking University Beijing100871 China

A bias-free source-independent quantum random number generator scheme based on the measurement of vacuum fluctuation is proposed to realize the effective elimination of system bias and common mode noise introduced by the local oscillator. Optimal parameter settings are derived to avoid the system recording two canonically conjugate quadratures simultaneously in each measurement. In particular, it provides a new approach to investigate the performance difference between measuring two quadratures of equal and unequal intensity. It is experimentally demonstrated that the system supports 4.2 Gbps bias-free source-independent random number generation, where its common mode rejection ratio reaches 61.17 dB. Furthermore, the scheme offers an all-optical method facilitating the integration of source-independent quantum random number generators into compact chips. Copyright © 2020, The Authors. All rights reserved.

关键词： Random number generation

Directly wireless communication of human minds via non-invasive brain-computer-metasurface platform

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arXiv 2022年

作者： Ma, Qian Gao, Wei Xiao, Qiang Ding, Lingsong Gao, Tianyi Zhou, Yajun Gao, Xinxin Yan, Tao Liu, Che Gu, Ze Kong, Xianghong Abbasi, Qammer H. Li, Lianlin Qiu, Cheng-Wei Li, Yuanqing Cui, Tie Jun Institute of Electromagnetic Space Southeast University Nanjing210096 China School of Automation Science and Engineering South China University of Technology Guangzhou510641 China State Key Laboratory of Millimeter Wave Southeast University Nanjing210096 China Center of Intelligent Metamaterials Pazhou Laboratory Guangzhou510330 China Research Center for Brain-Computer Interface Pazhou Lab Guangzhou510330 China Department of Electrical and Computer Engineering National University of Singapore Singapore Singapore University of Glasgow James Watt School of Engineering GlasgowG12 8QQ United Kingdom State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronics Peking University Beijing100871 China

Brain-computer interfaces (BCIs), invasive or non-invasive, have projected unparalleled vision and promise for assisting patients in need to better their interaction with the surroundings. Inspired by the BCI-based rehabilitation technologies for nerve-system impairments and amputation, we propose an electromagnetic brain-computer-metasurface (EBCM) paradigm, regulated by human's cognition by brain signals directly and non-invasively. We experimentally show that our EBCM platform can translate human's mind from evoked potentials of P300-based electroencephalography to digital coding information in the electromagnetic domain non-invasively, which can be further processed and transported by an information metasurface in automated and wireless fashions. Directly wireless communications of the human minds are performed between two EBCM operators with accurate text transmissions. Moreover, several other proof-of-concept mind-control schemes are presented using the same EBCM platform, exhibiting flexibly-customized capabilities of information processing and synthesis like visual-beam scanning, wave modulations, and pattern encoding. © 2022, CC BY.

关键词： Electrophysiology

Reconfigurable beam system for non-lineof-sight free-space optical communication

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Light(Science & Applications) 2019年第1期8卷 577-585页

作者： Zizheng Cao Xuebing Zhang Gerwin Osnabrugge Juhao Li Ivo M.Vellekoop Antonius M.J.Koonen Institute for Photonic Integration Eindhoven University of TechnologyPO Box 5135600 MB Eindhoventhe Netherlands Faculty of Science and Technology University of TwenteP.O.Box 2177500 AE Enschedethe Netherlands State Key Laboratory of Advanced Optical Communication Systems and Networks Peking UniversityBeijing 100871China

In this paper,we propose a reconfigurable beam-shaping system to permit energy-efficient non-line-of-sight(NLOS)free-space optical *** is steered around obstacles blocking the direct communication pathway and reaches a receiver after reflecting off of a diffuse surface.A coherent array optical transmitter(CAO-Tx)is used to spatially shape the wavefront of the light incident on a diffuse *** shaping is used to enhance the amount of diffusely reflected light reaching the optical *** NLOS experiments for a signal reflected over an angular range of 20°are presented.A record-breaking 30-Gbit/s orthogonal frequency-division multiplexing signal is transmitted over a diffused optical wireless link with a>17-dB gain.

关键词： communication beam reflected

Training Time Minimization for Federated Edge Learning with Optimized Gradient Quantization and Bandwidth Allocation

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arXiv 2021年

作者： Liu, Peixi Jiang, Jiamo Zhu, Guangxu Cheng, Lei Jiang, Wei Luo, Wu Du, Ying Wang, Zhiqin State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Beijing China Shenzhen Research Institute of Big Data Shenzhen China China Academy of Information and Communications Technology China College of Information Science and Electronic Engineering Zhejiang University Hangzhou China

Training a machine learning model with federated edge learning (FEEL) is typically time-consuming due to the constrained computation power of edge devices and limited wireless resources in edge networks. In this paper, the training time minimization problem is investigated in a quantized FEEL system, where the heterogeneous edge devices send quantized gradients to the edge server via orthogonal channels. In particular, a stochastic quantization scheme is adopted for compression of uploaded gradients, which can reduce the burden of per-round communication but may come at the cost of increasing number of communication rounds. The training time is modeled by taking into account the communication time, computation time and the number of communication rounds. Based on the proposed training time model, the intrinsic trade-off between the number of communication rounds and per-round latency is characterized. Specifically, we analyze the convergence behavior of the quantized FEEL in terms of the optimality gap. Further, a joint data- and-model-driven fitting method is proposed to obtain the exact optimality gap, based on which the closed-form expressions for the number of communication rounds and the total training time are obtained. Constrained by total bandwidth, the training time minimization problem is formulated as a joint quantization level and bandwidth allocation optimization problem. To this end, an algorithm based on alternating optimization is proposed, which alternatively solves the subproblem of quantization optimization via successive convex approximation and the subproblem of bandwidth allocation via bisection search. With different learning tasks and models, the validation of our analysis and the near-optimal performance of the proposed optimization algorithm are demonstrated by the experimental results. © 2021, CC BY-NC-SA.

关键词： Economic and social effects