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Analog spatiotemporal feature extraction for cognitive radio-frequency sensing with integrated photonics

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Light(Science & Applications) 2024年第3期13卷 478-487页

作者： Shaofu Xu Binshuo Liu Sicheng Yi Jing Wang Weiwen Zou State Key Laboratory of Advanced optical Communication Systems and Networks Intelligent Microwave Lightwave Integration Innovation Center(imLic)Department of Electronic EngineeringShanghai Jiao Tong UniversityShanghaiChina

Analog feature extraction(AFE)is an appealing strategy for low-latency and efficient cognitive sensing systems since key features are much sparser than the Nyquist-sampled ***,applying AFE to broadband radio-frequency(RF)scenarios is challenging due to the bandwidth and programmability bottlenecks of analog electronic ***,we introduce a photonics-based scheme that extracts spatiotemporal features from broadband RF signals in the analog *** feature extractor structure inspired by convolutional neural networks is implemented on integrated photonic circuits to process RF signals from multiple antennas,extracting valid features from both temporal and spatial *** of the tunability of the photonic devices,the photonic spatiotemporal feature extractor is trainable,which enhances the validity of the extracted ***,a digital-analog-hybrid transfer learning method is proposed for the effective and low-cost training of the photonic feature *** validate our scheme,we demonstrate a radar target recognition task with a 4-GHz instantaneous *** results indicate that the photonic analog feature extractor tackles broadband RF signals and reduces the sampling rate of analog-to-digital converters to 1/4 of the Nyquist sampling while maintaining a high target recognition accuracy of 97.5%.Our scheme offers a promising path for exploiting the AFE strategy in the realm of cognitive RF sensing,with the potential to contribute to the efficient signal processing involved in applications such as autonomous driving,robotics,and smart factories.

关键词： scheme driving smart

Ultra-low loss Rayleigh scattering enhancement via light recycling in fiber cladding

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Photonics Research 2024年第8期12卷 1813-1819页

作者： PENGTAO LUO FENGYI CHEN RUOHUI WANG XUEGUANG QIAO School of Physics Northwest UniversityXi’an 710127China Engineering Research center of optical Fiber Well Logging Technology for Oil and Gas Resources Universities of Shaanxi ProvinceXi’an 710127China

Rayleigh backscattering enhancement(RSE)of optical fibers is an effective means to improve the performance of distributed optical fiber *** laser direct-writing techniques have been used to modulate the fiber core for ***,in-core modulation loses more transmission light,thus limiting the sensing *** this work,a cladding-type RSE(cl-RSE)structure is proposed,where the femtosecond laser is focused in the fiber cladding and an array of scatterers is written parallel to the *** refractive-index modulation structure redistributes the light in the cladding,and the backward scattered light is recovered,which enhances the Rayleigh backscattered signal with almost no effect on the core light.

关键词： fiber scattering cladding

Thermally modulated photoelectronic synaptic behavior in HfS_(2)/VO_(2) heterostructure

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Rare Metals 2024年第8期43卷 3798-3809页

作者： Le Wang Lin Wang Xiao-Yun Ye Xiong-Hu Xu Li-Yan Shang Ya-Wei Li Jin-Zhong Zhang Liang-Qing Zhu Zhi-Gao Hu Technical center for Multifunctional Magneto-optical Spectroscopy(Shanghai) Engineering Research Center of Nanophotonics&Advanced Instrument(Ministry of Education)Department of PhysicsSchool of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China Collaborative Innovation center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Neuromorphic computing is known for its efficient computational speed,low latency,and reduced power consumption,which is considered a pivotal technology to overcome the von Neumann *** synapses are an indispensable component of neuromorphic computational artificial neural *** guarantee effective and precise processing of optical signals,it must have a high responsivity,detectivity,and the ability to adapt to various ***,a synaptic transistor based on the HfS_(2)/VO_(2) heterojunction with a responsivity of8.6×10^(3) A·W^(-1)and a detectivity of 1.26×10^(14)Jones at405 nm laser was ***,the typical synaptic behavior was successfully simulated,including postsynaptic currents(PSCs),the transition from shortterm plasticity(STP)to long-term plasticity(LTP).When VO_(2) converts from the semiconductor state to the metal state,the HfS_(2)/VO_(2) heterojunction transforms into a Schottky heterojunction from a TypeⅡheterojunction with ***'s important,the heterojunction still exhibits excellent responsivity and detectivity,as well as stability of synaptic *** addition,the classical Pavlovian conditioning experiment is simulated under different laser intensity to study the brain's associative learning *** results demonstrate that the HfS_(2)/VO_(2) heterojunction synapse exhibits significant responsivity and detectivity and is adaptable to high-temperature environments,showing great potential for neuromorphic computational applic ations.

关键词： HfS_(2) VO_(2) Phase transition Photoelectric synapse Heterojunction

optical properties of stacked liquid crystal superstructures with opposite chirality [Invited]

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Chinese Optics Letters 2024年第6期22卷 158-163页

作者： Lin Zhu Yiheng Zhang Shijun Ge Peng Chen Yanqing Lu National Laboratory of Solid State Microstructures Key Laboratory of Intelligent Optical Sensing and ManipulationCollege of Engineering and Applied Sciencesand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

Cholesteric liquid crystal (CLC) has been widely used in flat optical elements due to the Pancharatnam–Berry(PB) phase modulation. In order to achieve PB phase modulation for both circular polarizations, it is natural to come up with stacking CLCs with opposite chirality. Here, various optical properties of diverse CLC stacking structures are systematically investigated by numerical calculations. With the thickness of the CLC sublayers becoming smaller, the reflection bandgap splits into three main parts, and the rotatory dispersion gradually becomes negligible. Vector beams provide a more intuitive verification. These results provide theoretical guidance for future studies on stacked chiral anisotropic media.

关键词： cholesteric liquid crystals Pancharatnam–Berry phases chirality vector beams

Unveiling of Terahertz Emission from Ultrafast Demagnetization and the Anomalous Hall Effect in a Single Ferromagnetic Film

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Chinese Physics Letters 2024年第4期41卷 45-50页

作者：蓝志强李章顺徐浩然刘凡金钻明彭滟朱亦鸣 Terahertz Technology Innovation Research Institute Terahertz Spectrum and Imaging Technology Cooperative Innovation CenterShanghai Key Lab of Modern Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China

Using THz emission spectroscopy,we investigate the elementary spin dynamics in ferromagnetic single-layer Fe on a sub-picosecond *** demonstrate that THz radiation changes its polarity with reversal of the magnetization applied by the external magnetic *** addition,it is found that the sign of THz polarity excited from different sides is defined by the thickness of the Fe layer and Fe/dielectric *** on the thickness and symmetry dependences of THz emission,we experimentally distinguish between the two major contributions:ultrafast demagnetization and the anomalous Hall *** experimental results not only enrich understanding of THz electromagnetic generation induced by femtosecond laser pulses but also provide a practical way to access laser-induced ultrafast spin dynamics in magnetic structures.

关键词： magnetic magnetization polarity

Realization of one-dimensional 2^(n)-root topological states in photonic lattices

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Science China(Technological Sciences) 2024年第1期67卷 98-104页

作者： WEI RuiShan ZHANG QingLong YANG DanDan HUANG XiongJian PAN QiWen KANG Juan QIU JianRong YANG ZhongMin DONG GuoPing State Key Laboratory of Luminescent Materials and Devices and Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesGuangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and DevicesSchool of Materials Science and EngineeringSouth China University of TechnologyGuangzhou 510640China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China State Key Laboratory of Modern optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China

Square-root topological insulators recently discovered are intriguing topological *** possess topological properties inherited from the squared Hamiltonian and exhibit double-band *** mechanism of the square root was generalized to 2^(n)-root topological insulators,giving rise to more band *** this study,we describe the experimental realization of onedimensional 2^(n)-root topological insulators in photonic waveguide arrays using the archetypical Su-Schrieffer-Heeger(SSH)*** edge states with tunable numbers are clearly observed under visible *** particular,we visualized the dynamic evolutions of the light propagation by varying the sample lengths,which further proved the localization and multiple numbers of edge states in 2^(n)-root topological *** experiment,which involves constructing 2^(n)-root topological photonic lattices in various geometric arrangements,provides a stable platform for studying topological states that exhibit a remarkable degree of flexibility and control.

关键词： 2^(n)-root topological insulators multiple edge states photonic waveguide arrays light dynamics

Road map for, and technical challenges of, carbon-nanotube integrated circuit technology

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National Science Review 2024年第3期11卷 14-16页

作者： Jia Si Panpan Zhang Zhiyong Zhang Key Laboratory for the Physics and Chemistry of Nanodevices and center for Carbon-based Electronics School of Electronics Peking University State Key Laboratory of Information Photonics and optical Communications Beijing University of Posts and Telecommunications

The past decade has witnessed an explosion of research on carbon-nanotube(CNT) electronics due to their outstanding properties, including an ultrathin body, a high carrier mobility and a high saturation velocity.

关键词： TRANSISTORS

Investigation and mitigation of Mott neuronal oscillation fluctuation in spiking neural network

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Science China(Information Sciences) 2024年第2期67卷 291-301页

作者： Lindong WU Zongwei WANG Lin BAO Linbo SHAN Zhizhen YU Yunfan YANG Shuangjie ZHANG Guandong BAI Cuimei WANG John ROBERTSON Yuan WANG Yimao CAI Ru HUANG School of Integrated Circuits Peking University Beijing Advanced Innovation center for Integrated Circuits State Key Laboratory of Information Photonics and optical Communications Beijing University of Posts and Telecommunications Department of Engineering University of Cambridge

Mott devices, featuring low hardware cost and high energy efficiency, have been demonstrated as a key oscillatory element in artificial neurons to enable spiking neural networks(SNNs) such as conversionbased SNNs(CSNNs). However, there will be inevitably non-ideal fluctuation in the oscillation behavior,causing the accuracy degradation of networks. In this paper, we investigate the Mott neuronal oscillation fluctuation(NOF) through experiments and modeling. The results show that the NOF phenomenon conforms to Gaussian distribution and originates from thermal fluctuation induced switching voltage variations. We construct a two-layer CSNN for image recognition tasks to study the NOF effect and propose the activation function boundary(AFB) method to strengthen the stability of the network. The results indicate that AFB can improve the accuracy of CSNN by up to 15.5% by tightening output distribution.

关键词： Mott neuron oscillation fluctuation variation-aware Mott neuronal model conversion-based spiking neural network activation function boundary

Experimental demonstration of a quantum downstream access network in continuous variable quantum key distribution with a local local oscillator

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Photonics Research 2024年第6期12卷 1262-1273页

作者： DENGKE QI XIANGYU WANG ZHENGHUA LI JIAYU MA ZIYANG CHEN YUEMING LU SONG YU State Key Laboratory of Information Photonics and optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China Key Laboratory of Trustworthy Distributed Computing and Service(MoE) Beijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory of Advanced optical Communication Systems and Networks School of Electronicsand Center for Quantum Information TechnologyPeking UniversityBeijing 100871China

Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers,including quantum computation,communication,and *** traditional communication networks,quantum networks utilize quantum bits rather than classical bits to store and transmit *** key distribution(QKD)relying on the principles of quantum mechanics is a key component in quantum networks and enables two parties to produce a shared random secret key,thereby ensuring the security of data *** this work,we propose a cost-effective quantum downstream access network structure in which each user can get their corresponding key information through terminal *** on this structure,we demonstrate the first four-end-users quantum downstream access network in continuous variable QKD with a local local *** contrast to point-to-point continuous variable QKD,the network architecture reevaluates the security of each user and accounts for it accordingly,and each user has a lower tolerance for excess noise as the overall network expands with more ***,the feasibility of the experiment is based on the analysis of the theoretical model,noise analysis,and multiple techniques such as the particle filter and adaptive equalization algorithm used to suppress excess *** results show that each user can get a low level of excess noise and can achieve secret key rates of 546 kbps,535 kbps,522.5 kbps,and 512.5 kbps under a transmission distance of 10 km,respectively,with the finite-size block of 1×10~*** not only verifies the good performance but also provides the foundation for the future multi-user quantum downstream access networks.

关键词： quantum oscillator local