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arXiv 2024年

作者： Liu, Boxun Gao, Shijian Yang, Zonghui Cheng, Xiang State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Beijing China Guangzhou China

Integrated Sensing and communication (ISAC) emerges as a promising technology for B5G/6G, particularly in the millimeter-wave (mmWave) band. However, the widespread adoption of hybrid architecture in mmWave systems compromises multiplexing gain due to limited radio-frequency chains, resulting in mediocre performance when embedding sensing functionality. To avoid sacrificing the spectrum efficiency in hybrid structures while addressing performance bottlenecks in its extension to ISAC, we present an optimized beam pattern modulation-embedded ISAC (BPM-ISAC). BPM-ISAC applies index modulation over beamspace by selectively activating communication beams, aiming to minimize sensing beampattern mean squared error (MSE) under communication MSE constraints through dedicated hybrid transceiver design. Optimization involves the analog part through a min-MSE-based beam selection algorithm, followed by the digital part using an alternating optimization algorithm. Convergence and asymptotic pairwise error probability (APEP) analyses accompany numerical simulations, validating its overall enhanced ISAC performance over existing alternatives. Copyright © 2024, The Authors. All rights reserved.

关键词： Mean square error

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Quantum Sensing of Magnetic Fields Using Global Optimization Algorithms

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Physical Review Applied 2023年第2期20卷 024042-024042页

作者： Wei Xiao Yudong Ding Teng Wu Xiang Peng Hong Guo State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Center for Quantum Information Technology Peking University Beijing 100871 China

Experimentally achieving optimal performance of quantum sensors, such as optically pumped magnetometers, is usually challenging and time consuming due to the complexity of the physical system. For a given experiment scheme, there are usually many experiment parameters that need to be fine tuned for achieving a satisfying performance of the quantum sensor. By employing global optimization algorithms, we propose an automatic and efficient way to optimize the sensor performance. We take the most sensitive magnetic field sensor, i.e., the optically pumped magnetometer, as an example to demonstrate how these algorithms facilitate the automatic optimization of quantum sensors. Both the optimization of zero-field magnetometers in a magnetic shield and the finite-field magnetometers in open Earth’s field are demonstrated. A noise floor of approximately 10fT/Hz1/2 is achieved within a short time. This method provides an efficient way for quantum sensor optimization and will be helpful for the quantum sensor design.

关键词： Atomic & molecular processes in external fields Optimization problems Quantum algorithms Quantum measurements Quantum metrology Quantum sensing optically detected magnetic resonance

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Squint-Aware ISAC Precoding Towards Enhanced Dual-Functional Gain in Sub-Terahertz systems

arXiv

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arXiv 2024年

作者： Yang, Zonghui Gao, Shijian Cheng, Xiang State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Beijing China Guangzhou China

The potential benefits of integrated sensing and communication (ISAC) are anticipated to play a significant role in future sub-terahertz (sub-THz) systems. However, the beam squint effect is pronounced in sub-THz systems, expanding coverage areas while severely degrading communication performance. Existing hybrid precoding designs struggle to balance both functionalities in the presence of beam squint, limiting the performance gain achievable through ISAC. To address this challenge, we propose two squint-aware hybrid precoding schemes for sub-THz systems that proactively regulate the correlation between communication and sensing channels, leveraging the inherent degrees of freedom in the hardware to enhance integrated gain. We introduce a squint-aware optimization-based hybrid precoding algorithm (SA-Opt) and develop an unsupervised learning-assisted complex-valued squint-aware network (CSP-Net) to reduce complexity, tailoring its architecture to the specific data and task characteristics. The effectiveness of the proposed schemes is demonstrated through simulations. Copyright © 2024, The Authors. All rights reserved.

关键词： Terahertz wave detectors

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Low temperature sensitivity on-chip Fouriertransform spectrometer based on dual-layer Si_(3)N_(4)spiral waveguides

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Photonics Research 2023年第4期11卷 591-599页

作者： LIANGJUN LU HONGYI ZHANG XIN LI JIANPING CHEN LINJIE ZHOU State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Key Laboratory of Navigation and Location ServicesDepartment of Electronic EngineeringShanghai Jiao Tong UniversityShanghai 200240China SJTU-Pinghu Institute of Intelligent Optoelectronics Pinghu 314200China

On-chip Fourier-transform spectrometers(FTSs)based on Mach–Zehnder interferometer(MZI)arrays suffer from severe central wavelength and fringe contrast variation due to fabrication *** though a calibration matrix can be employed to correctly retrieve the input spectra,environmental temperature variation greatly degrades the retrieving *** this paper,we devise a dual-layer Si_(3)N_(4) waveguide interferometer to reduce the temperature *** beating of the even and odd supermodes in the dual-layer waveguide generates periodic intensity fluctuations in the *** these two modes have similar modal profiles,their thermal sensitivity and propagation loss are relatively balanced,leading to a low temperature sensitivity and a high interference extinction *** designed and fabricated a passive FTS based on a 32-channel dual-layer Si_(3)N_(4) waveguide *** results show that the temperature sensitivity is reduced to 10 pm/°C,which is almost half that of single-layer Si_(3)N_(4) MZI-based *** this chip,we accurately reconstructed various types of optical spectra,including single and two sparse laser lines,and broadband optical *** method can fit a wide wavelength range,which is a promising technology to improve the practical applications of on-chip FTSs.

关键词： waveguide interferometer layer

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100 Gb/s coherent chaotic optical communication over 800 km fiber transmission via advanced digital signal processing

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advanced Photonics Nexus 2024年第1期3卷 20-25页

作者： Yunhao Xie Zhao Yang Mengyue Shi Qunbi Zhuge Weisheng Hu Lilin Yi Shanghai Jiao Tong University School of Electronic Information and Electrical EngineeringState Key Laboratory of Advanced Optical Communication Systems and NetworksShanghaiChina

Chaotic optical communication has shown large potential as a hardware encryption method in the physical *** an important figure of merit,the bit rate–distance product of chaotic optical communication has been continually improved to 30 Gb/s×340 km,but it is still far from the requirement for a deployed optical fiber communication system,which is beyond 100 Gb/s×1000 km.A chaotic carrier can be considered as an analog signal and suffers from fiber channel impairments,limiting the transmission distance of high-speed chaotic optical *** break the limit,we propose and experimentally demonstrate a pilot-based digital signal processing scheme for coherent chaotic optical communication combined with deep-learning-based chaotic *** transmission impairment recovery and chaotic synchronization are realized in the digital *** frequency offset of the lasers is accurately estimated and compensated by determining the location of the pilot tone in the frequency domain,and the equalization and phase noise compensation are jointly performed by the least mean square algorithm through the time domain pilot *** the proposed method,100 Gb∕s chaotically encrypted quadrature phase-shift keying(QPSK)signal over 800 km single-mode fiber(SMF)transmission is experimentally *** order to enhance security,40 Gb∕s real-time chaotically encrypted QPSK signal over 800 km SMF transmission is realized by inserting pilot symbols and tone in a field-programmable gate *** method provides a feasible approach to promote the practical application of chaotic optical communications and guarantees the high security of chaotic encryption.

关键词： chaotic optical communication physical layer security deep learning digital signal processing

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Efficient coupling modulation of silicon racetrack ring resonators at 2 μm waveband

Efficient coupling modulation of silicon racetrack ring reso...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Wang, Xi Wu, You Wang, Jianing Li, Jian Li, Yihang Du, Jiangbing Wang, Lei He, Zhixue Xiao, Xi Xu, Ke Department of Electronic and Information Engineering Harbin Institute of Technology Shenzhen518055 China State Key Laboratory of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Shanghai200240 China Peng Cheng Laboratory Shenzhen518055 China

We have experimentally demonstrated 30 Gbit/s coupling modulation based on silicon racetrack ring resonator operating at 2 μm waveband. The modulator has EO bandwidth beyond 18 GHz and modulation efficiency of 0.75 V... 详细信息

ISBN: (纸本)9781957171258

关键词： Silicon

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Mixed-Precision Integer-Arithmetic-Only Neural Network-Based Equalizers for DML-Based Short-Reach IM/DD systems 49

Mixed-Precision Integer-Arithmetic-Only Neural Network-Based...

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49th European Conference on optical communications, ECOC 2023

作者： Xu, Zhaopeng Ji, Honglin Yang, Yu Qiao, Gang Wu, Qi Li, Jia Lu, Weiqi Liu, Lulu Wang, Shangcheng Wei, Jinlong He, Zhixue Hu, Weisheng Shieh, William Peng Cheng Laboratory Shenzhen518055 China State Key Lab of Advanced Optical Communication Systems and Networks Shanghai Jiao Tong University Shanghai200240 China School of Engineering Westlake University Hangzhou310024 China

ISBN: (纸本)9781839539954

We propose mixed-precision integer-Arithmetic-only NNs for low-complexity equalization in a 50-Gb/s 25-km DML-based PAM4 IM/DD link based on input neuron partitioning. The proposed scheme avoids floating-point weight operations and saves 26.3% memory at a minimum NN size compared with fixed-precision quantization counterpart without degrading BER. © The Institution of Engineering & Technology 2023.

关键词： Mixed-integer linear programming

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Dual-Species All-optical Magnetometer Based on a Cs-K Hybrid Vapor Cell

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Physical Review Applied 2023年第3期19卷 034066-034066页

作者： Yudong Ding Wei Xiao Yixin Zhao Teng Wu Xiang Peng Hong Guo State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Center for Quantum Information Technology Peking University Beijing 100871 China

We build and characterize a dual-species all-optical magnetometer based on a Cs-K hybrid vapor cell with a paraffin coating. Using the amplitude-modulated Bell-Bloom scheme and Faraday-rotation measurement, we show that the spin polarization of Cs and K atoms can be generated and detected independently. The noise floor of the Cs channel is 35fT/Hz, whereas that of the K channel is 260fT/Hz, which is affected mainly by the magnetic resonance broadening in the presence of mutual spin-exchange collisions. With use of the proposed device, in situ magnetic field stabilization is realized by use of (i) the K channel to monitor and compensate for the magnetic field noise and (ii) the Cs channel to read out the magnetic field after active stabilization. The low-frequency magnetic field noise can be suppressed by a factor of more than 1000 in the presence of magnetic field gradients. When applied to magnetic field stabilization, such in situ measurement is achieved more compactly and is more accurate than ex situ measurement that is realized with two spatially separated vapor cells. In addition, the proposed scheme could also be applied in a practical ground-surveying magnetometer based on dual working species.

关键词： Magneto-optical spectra Quantum sensing Zeeman effect Alkali metals Atomic gases Magnetic moment Polarization

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Dispersion Characterization of Dielectric Two-Dimensional Photonic Band Gap

Dispersion Characterization of Dielectric Two-Dimensional Ph...

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International Conference on Microwave and Millimeter Wave Technology Proceedings

作者： Yu-Lu Lei Zi-Wen Zhang Chao-Hai Du Center for Carbon-based Electronics State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University

ISBN: (数字)9798350389968

ISBN: (纸本)9798350389975

Dielectric photonic crystals, characterized by periodic refractive index modulation, give rise to photonic band gaps (PBGs), offering a novel avenue for controlling the propagation of electromagnetic waves. In this study, we aim to investigate the correlation between the ratio of the lattice constant to the rod radius and the PBG. Employing the Finite-Difference Frequency-Domain method, we calculate the dispersions along the boundary of the irreducible Brillouin zone, which are visually presented in the figures. This exploration promises to introduce a completely new degree of freedom for the manipulation of light or electromagnetic wave propagation.

关键词： Photonic band gap Two-dimensional displays Millimeter wave technology Lattices Modulation Refractive index Millimeter wave propagation

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Broadband optically Transparent Absorber and Multi-Band Stealth Based on Organic Metasurface

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Chinese Physics Letters 2025年第5期42卷 93-99页

作者： Chuwen Lan Yutong Gao Zehua Gao Hongye Wang Ke Bi Ming Lei Guoan Zhao School of Information and Communication Engineering Beijing Laboratory of Advanced Information NetworksBeijing Key Laboratory of Network System Architecture and ConvergenceBeijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory of Information Photonics and Optical Communications School of ScienceBeijing University of Posts and TelecommunicationsBeijing 100876China School of Integrated Circuits Beijing University of Posts and TelecommunicationsBeijing 100876China Network Education College of Beijing University of Posts and Telecommunications Beijing 100876China

optically transparent microwave absorbers and multi-band stealth have extensive potential applications in military defense and wireless communication fields, and thus have attracted considerable attention. So far,most related work is based on inorganic transparent conductive metasurfaces. In this paper, we proposed and experimentally demonstrated a flexible, broadband and optically transparent microwave absorber using an organic metasurface. The metasurface absorber is composed of a sandwich structure, in which electric resonances and magnetic resonances are induced resulting in broadband absorption. A spraying process was developed to prepare this metasurface absorber. Both simulations and experiment show that this metasurface has broadband microwave absorption and good optical transparency. We further found that by using a multi-layer structure, visible, radar,and infrared stealth(multi-band stealth) can be achieved simultaneously. With the advantages of excellent foldability and low cost, the proposed metasurfaces may have applications in military and wireless communication fields.

关键词： microwave absorber broadband microwave absorption organic metasurface metasurface absorber microwave absorbers inorganic transparent conductive metasurfaces military defense sandwich structure

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