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Compact 459 nm Cs cell optical frequency standard with 2.1 × 10−13/√τ short-term stability

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arXiv 2022年

作者： Miao, Jianxiang Shi, Tiantian Zhang, Jia Chen, Jingbiao State Key Laboratory of Advanced Optical Communication System and Network School of Electronics Peking University Beijing100871 China

We achieve a compact optical frequency standard with an extended cavity diode laser locked to the 459 nm 6S1/2 - 7P1/2 transition of thermal 133Cs atoms in a φ 10 mm × 50 mm glass cell, using modulation transfer spectroscopy (MTS). The self-estimated frequency stability of this laser is 1.4×10−14/√τ. With heterodyne measurement, we verify the linewidth-narrowing effect of MTS locking and measure the frequency stability of the locked laser. The linewidth of each laser is reduced from the free-running 69.6 kHz to 10.3 kHz after MTS stabilization, by a factor of 6.75. The Allan deviation measured via beat detection is 2.1×10−13/√τ for each MTS-stabilized laser. In addition, we measure the hyperfine structure of the 7P1/2 energy level based on the heterodyne measurements, and calculate the magnetic dipole constant A of the Cs 7P1/2 level to be 94.38(6) MHz, which agrees well with previous measurements. This compact optical frequency standard can also be used in other applications that require high-stability lasers, such as laser interferometry, laser cooling, geodesy, and so on. © 2022, CC BY.

关键词： Glass transition

Integrated adaptive coherent LiDAR for 4D bionic vision

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arXiv 2024年

作者： Chen, Ruixuan Wu, Yichen Zhang, Ke Liu, Chuxin Chen, Yikun Li, Wencan Shen, Bitao Chen, Zhaoxi Feng, Hanke Ge, Zhangfeng Zhou, Yan Tao, Zihan Xu, Weihan Wang, Yimeng Cai, Pengfei Pan, Dong Shu, Haowen Zhou, Linjie Wang, Cheng Wang, Xingjun State Key Laboratory of Advanced Optical Communications System and Networks School of Electronics Peking University Beijing100871 China Department of Electrical Engineering State Key Laboratory of Terahertz and Millimeter Waves City University of Hong Kong Hong Kong State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China Peking University Yangtze Delta Institute of Optoelectronics Nantong226010 China Frontiers Science Center for Nano-optoelectronics Peking University Beijing100871 China SiFotonics Technologies Co. Ltd. Beijing China

Light detection and ranging (LiDAR) is a ubiquitous tool to provide precise spatial awareness in various perception environments. A bionic LiDAR that can mimic human-like vision by adaptively gazing at selected regions of interest within a broad field of view is crucial to achieve high-resolution imaging in an energy-saving and cost-effective manner. However, current LiDARs based on stacking fixed-wavelength laser arrays and inertial scanning have not been able to achieve the desired dynamic focusing patterns and agile scalability simultaneously. Moreover, the ability to synchronously acquire multidimensional physical parameters, including distance, direction, Doppler, and color, through seamless fusion between multiple sensors, still remains elusive in LiDAR. Here, we overcome these limitations and demonstrate a bio-inspired frequency-modulated continuous wave (FMCW) LiDAR system with dynamic and scalable gazing capability. Our chip-scale LiDAR system is built using hybrid integrated photonic solutions, where a frequency-chirped external cavity laser provides broad spectral tunability, while on-chip electro-optic combs with elastic channel spacing allow customizable imaging granularity. Using the dynamic zoom-in capability and the coherent FMCW scheme, we achieve a state-of-the-art resolution of 0.012 degrees, providing up to 15 times the resolution of conventional 3D LiDAR sensors, with 115 equivalent scanning lines and 4D parallel imaging. We further demonstrate cooperative sensing between our adaptive coherent LiDAR and a camera to enable high-resolution color-enhanced machine vision. With its beyond-retinal resolution, flexible gazing ability, as well as low-cost chip manufacturability, our bionic LiDAR solution paves the way for high-resolution adaptive 4D-plus machine vision that could benefit a wide range of applications, including autonomous driving, intelligent robotics, and electric vertical take-off and landing (eVTOL) aircraft. © 2024, CC BY.

关键词： Intelligent robots

Experimental observation of Kerr-Raman solitons in a normal-dispersion FP resonator

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arXiv 2023年

作者： Li, Tieying Wu, Kan Zhang, Xujia Cai, Minglu Chen, Jianping State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronic Information and Electrical Engineering Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China

Dissipative Kerr nonlinear cavities attract intense interest due to their rich dynamics and capability to generate broadband, low-noise mode-locked optical frequency combs for applications in optical communications, dual-comb spectroscopy, and photonic lidar, etc. Different from the Kerr effect, which is an electronic response, stimulated Raman scattering (SRS) is a delayed response to molecular vibrations in materials. In microcavities, when driven in an anomalous group velocity dispersion (GVD) regime, SRS typically leads to self-frequency shift of solitons and generation of breather solitons which have been verified both theoretically and experimentally. However, when driven in a normal GVD regime, recent theoretical work predicts that SRS can cause the locking of switching waves (SWs) and thus support bright moving localized structures (LSs), which we term as Kerr-Raman solitons (KRSs). Limited by the design of suitable experimental parameters, experimental observation of the KRSs is not achieved yet. Here, we provide numerical investigation, and to our knowledge, the first experimental observation of these SRS enabled KRSs in a fiber Fabry-Perot (FP) resonator with ultra-low normal GVD. Such Kerr-Raman solitons exhibit localized temporal features with strong oscillations at ~13 THz local frequency on the top of a flat-top pulse. The corresponding spectrum is a low-noise and broadband Kerr comb with typical platicon-like spectrum in the center and two Raman Stokes and anti-Stokes peaks located near ±13 THz away from the center. With such SRS enabled broadband Kerr comb, we have achieved a KRS spectrum with a repetition rate of ~3.68 GHz and a -40 dB spectral width of 260 nm. The corresponding comb tooth count is >9000, covering the S+C+L telecommunication bands. Moreover, the formation process of such KRSs is also revealed, and it is found that the GVD plays a key role in its generation. Our work will help to advance the study of the dynamics of optical frequenc

关键词： Stimulated Raman scattering

A quasi-3D Fano resonance cavity on optical fiber end-facet for high signal-to-noise ratio dip-and-read surface plasmon sensing

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Light(advanced Manufacturing) 2022年第4期3卷 39-49页

作者： Xiaqing Sun Zeyu Lei Hao Zhong Chenjia He Sihang Liu Qingfeng Meng Qingwei Liu Shengfu Chen Xiangyang Kong Tian Yang State Key Laboratory of Advanced Optical Communication Systems and Networks Key Laboratory for Thin Film and Microfabrication of the Ministry of EducationSchool of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China School of Material Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Biomass Chemical Engineering College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China

Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation *** present,these devices’noise-equivalent limits-of-detection lag far behind the free-space counterparts,leaving them incapable of most biosensing *** we report a quasi-3D Fano resonance cavity and its fabrication method to fundamentally improve the quality factor and coupling efficiency for fiber-coupled surface plasmon *** this device,the Fano resonance combines the high coupling efficiency of a Fabry-Pérot etalon and the high quality factor resonance of a plasmonic crystal *** quasi-3D device was fabricated on a planar substrate and transferred to a single-mode fiber end-facet,which requires a low-adhesion yet surface-plasmon-tunneling interface between the device and the planar *** an interface was realized with a nanocap-slit unit structure,of which the plasmonic crystal was consisted.A noise-equivalent limit of detection of~10-7 RIU was experimentally obtained,allowing bovine serum albumin physical adsorption to be distinguished at ng mL-1 level ***,breaking through the long-standing signal-to-noise ratio bottleneck,this work makes fiber end-facet surface plasmon devices into one of high sensitivity label-free sensing *** the same time,it provides an enabling top-down fabrication technology for making 3D plasmonic structures on fiber end-facets at the nanometer scale.

关键词： Surface plasmon Fano resonance Fiber end-facet

Non-volatile electrically reconfigurable optical MZI integrated with Sb2Se3 sub-cell arrays for high endurance switching

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Non-volatile electrically reconfigurable optical MZI integra...

49th European Conference on optical communications (ECOC 2023)

作者： X. Yang L. Lu Y. Li J. Chen L. Zhou State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Key Lab of Navigation and Location Services Shanghai Institute for Advanced Communication and Data Science Department of Electronic Engineering Shanghai Jiao Tong University Shanghai 200240 People's Republic of China

We demonstrated an electrical-driven non-volatile MZI based on low-loss Sb 2 Se 3 sub-cell arrays. By constraining the material reflow in the sub-cells, optical transmission contrast of > 5 dB was achieved with &g...

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Capillary-Based Structural Long-Period Gratings for High-Sensitivity Curvature and Strain Measurement

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Capillary-Based Structural Long-Period Gratings for High-Sen...

International Conference on optical communications and networks (ICOCN)

作者： Mengjiao Ding Mengxue Tang Xin Wang Ziyang Hua Yunhe Zhao Institute of Logistics Science and Engineering Shanghai Maritime University Shanghai China State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Shanghai China

A structural long-period gratings built with cascaded-sections of capillaries for high-sensitive curvature and strain measurement is proposed and experimentally demonstrated, and the correspondent sensitivities of 29....

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Deep Learning-Assisted Simultaneous Targets Sensing and Super-Resolution Imaging

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arXiv 2023年

作者： Zhao, Jin Zhang, Huang Zhao Chong, Ming-Zhe Zhang, Yue-Yi Zhang, Zi-Wen Zhang, Zong-Kun Du, Chao-Hai Liu, Pu-Kun State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Beijing100871 China School of Computer Science Peking University Beijing100871 China

Recently, metasurfaces have experienced revolutionary growth in the sensing and super-resolution imaging field, due to their enabling of sub-wavelength manipulation of electromagnetic waves. However, the addition of metasurfaces multiplies the complexity of retrieving target information from the detected fields. Besides, although the deep learning method affords a compelling platform for a series of electromagnetic problems, many studies mainly concentrate on resolving one single function and limit the research’s versatility. In this study, a multifunctional deep neural network is demonstrated to reconstruct target information in a metasurface-targets interactive system. Firstly, the interactive scenario is confirmed to tolerate the system noises in a primary verification experiment. Then, fed with the electric field distributions, the multitask deep neural network can not only sense the quantity and permittivity of targets but also generate super-resolution images with high precision. The deep learning method provides another way to recover targets’ diverse information in metasurface-based target detection, accelerating the progression of target reconstruction areas. This methodology may also hold promise for inverse reconstruction or forward prediction problems in other electromagnetic scenarios. Copyright © 2023, The Authors. All rights reserved.

关键词： Electromagnetic waves

Bulk Transfers With GCN Scheduling In Digital Twin networks

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Bulk Transfers With GCN Scheduling In Digital Twin Networks

IEEE International Conference on communications (ICC)

作者： Xiao Lin Lanfang Zheng Keqin Shi Yajie Li College of Physics and Information Engineering Fuzhou University Fuzhou China State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Shanghai China State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing China

Digital Twin Network (DTN) constructs a many-to-many mapping network by communicating and collaborating with massive Digital Twins (DTs), which can better assist the management and operation of large-scale modern systems. However, the emergence of DTN mirrors a growing demand for bulk data transfer between geo-distributed DT nodes in the physical network infrastructure. Conventional end-to-end connections are facing a great challenge in the presence of the background traffic fluctuation. In this paper, we propose a graph convolutional network (GCN)-enabled scheduling method to schedule bulk data transfers across the DTN in a store-and-forward (SnF) manner. Instead of solving the complex SnF scheduling problem on the entire network, the proposed method decomposes the problem into multiple sub-problems on different pre-computed routes. Instead of learning the scheduling results directly, the GCN model is used to predict the reachability of DT nodes. These unreachable nodes will be excluded from the scheduling process. Our studies show that the proposed method obtains better network performance and lower complexity when compared with the conventional scheduling methods.

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Transfer Learning assisted Beam Training via Large-Scale Intelligent Omni-surface in Dynamic Environments

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Transfer Learning assisted Beam Training via Large-Scale Int...

IEEE Conference on Vehicular Technology (VTC)

作者： Zhihan Chen Shuhang Zhang Shuhao Zeng Boya Di School of Electronics Engineering and Computer Science Peking University Beijing China State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Beijing China

Intelligent omni-directional surfaces (IOS), which can simultaneously reflect and refract incident signals, are considered as a promising solution for enhancing communication quality. To conduct joint beamforming of the BS and IOS, beam training is introduced such that perfect channel state information is not required anymore. However, the propagation environment is usually dynamically varying in practice, leading to frequent beam training procedures and huge training overhead. In this paper, we propose a transfer learning based beam training scheme for the IOS-assisted multi-user system to adapt to the dynamically changing propagation environment. We first build on an offline phase to train a beam prediction model that outputs the optimal beam with the highest data rate given only the received power of a small number of beams as the input. Then a transfer learning based method is developed such that the above beam prediction model can be updated to adapt to the dynamic environment rapidly. Simulation results demonstrate that the proposed scheme outperforms the existing beam training schemes in dynamic environments in terms of the convergence speed and the sum rate.

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