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Continuous-wave 2.9–3.8 μm random lasing via temperature-tunning free difference-frequency generation of random fiber lasers in PPLN crystal

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Science China(information Sciences) 2023年第8期66卷 279-280页

作者： Bo HU Han WU Kan TIAN Houkun LIANG College of Electronics and Information Engineering Sichuan University

Continuous-wave(CW) tunable mid-infrared(MIR) laser sources are necessary for laser spectroscopy, remote sensing,and infrared imaging applications [1]. Generally, quantum cascaded lasers(QCLs) are mature MIR radiation sources with decent power. However, the tunning range of QCLs is limited to ten of cm-1. In contrast, difference-frequency generation(DFG) sources based on nonlinear optical crystals have advantages in broad wavelength tunability.

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Optical waveguide in curved and welded perovskite nanowires

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Science China(Technological Sciences) 2023年第5期66卷 1471-1479页

作者： ZHANG ZhenYu ZHANG YuPeng HONG BinBin WANG GuoPing College of Electronics and Information Engineering Shenzhen UniversityShenzhen 518060China

Single-crystalline lead halide perovskite nanowires are emerging as promising one-dimensional blocks for nanoscience and nanotechnology,and extensive studies of nano-lasers and nano-photodetectors have been reported.However,as perfect confined structures,their optical waveguide performances have not been widely paid attention to up to now.Here,we report on the such issue on single-crystalline CsPbBr3nanowires and quantify it by near-field optical response mappings.The waveguide is verified as total internal reflection mode at the visible band(532 nm),and its far-field end-facet coupling efficiency of 89.6%and propagation loss as low as 5.9 dB/mm are measured from the nanowire with cross-sectional geometry of~600 nm×300 nm.No evident bending loss exists in naturally curved nanowires,while it usually emerges in artificial-bended ones due to the wrinkled surfaces.Naturally welded nanowire networks show significant advantages in integrated waveguides over the artificial assembled ones,due to the coupled photons at the space-confined end-facet segments.Roughened surface reasoned by lattice degradation is detrimental to propagation loss,but it provides leaked channels for waveguide coupling on nanowire surface.This work studies the optical waveguide performance of perovskite nanowires with different geometries and goes a step further for integrated nanophotonics.

关键词： optical waveguide perovskite nanowires SNOM curved nanowire welded networks

Renewable Microgrid Protection Strategy Coordinating with Current-based Fault Control

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Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1679-1689页

作者： Zihao Wang Longhua Mu Chongkai Fang College of Electronics and Information Engineering Tongji UniversityShanghai 201804China

The renewable microgrid(RMG)is a critical way to organize and utilize new energy.Its control and protection strategies during the fault are the core technologies to ensure the safe operation and stability of the system.The traditional protection principles are unsuitable for RMGs due to the flexibility of RMG operation,the complexity of RMG topology,and the variety of fault control strategies of inverter-interfaced distributed generators(IIDGs).The traditional fault component protection principle is affected by the low voltage ride-through(LVRT)control strategy and will fail in some scenarios.In order to make the fault component protection principle available in every scenario,a current-based fault control strategy is proposed.Specific fault characteristics are generated by the grid-feeding IIDGs during the fault so they can be equivalent to the open circuits,and the fault models in additional network can be simplified.By analyzing the fault characteristics,an RMG protection strategy based on the current-based fault control of IIDGs is presented.The fault directions of feeders can be distinguished and the fault feeder can be located accurately in both grid-connected and islanded RMGs.Then,the grid-feeding IIDGs can transit to LVRT mode smoothly.Thus,IIDGs are considered comprehensively in terms of coordinating with fault control and fault characteristic generation.Finally,the experimental results of the hardware platform prove the effectiveness of the proposed current-based fault control strategy,and the simulation results based on PSCAD/EMTDC verify the correctness of the protection strategy.

关键词： Renewable microgrid protection strategy fault characteristic control strategy fault component

An Ultra-Compact Broadband Polarizing Beam Splitter Utilizing Hybrid Plasmonic Waveguide

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China Communications 2023年第6期20卷 49-59页

作者： Li Zhang Jiaqi Liu Can Pan Yatao Yang College of Electronics and Information Engineering Shenzhen UniversityShenzhen 518000China

Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide.The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer.Therefore,we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides.First,we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides,and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode.Then,the performance of our proposed polarizing beam splitter is evaluated numerically.The length of the coupling section is only 4.1μm,and the propagation loss of TM and TE modes is 0.0025 d B/μm and 0.0031 d B/μm respectively.Additionally,the extinction ratios of TM and TE modes are 10.62 d B and 12.55 d B,respectively.Particularly,the proposed device has excellent wavelength insensitivity.Over the entire C-band,the fluctuation of the whole normalized output power is less than 0.03.In short,our proposed asymmetric polarizing beam splitter features ultra-compactness,low propagation loss,and broad bandwidth,which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.

关键词： polarizing beam splitter hybrid plasmonic waveguide directional coupler polarization multiplexing systems

TDOA estimation of dual-satellites interference localization based on blind separation

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Journal of Systems Engineering and electronics 2019年第4期30卷 696-702页

作者： SU Ting GAO Yong College of Electronics and Information Engineering Sichuan University

The time difference of arrival(TDOA)estimation plays a crucial role in the accurate localization of the satellite interference source.In the dual-satellites interference source localization system,the target signal from the adjacent satellite is likely to be interfered by the normal communication signal with the same frequency.Therefore,the signal to noise ratio(SNR)of the target signal would become too low,and the TDOA estimation through cross-correlation processing would be unreliable or even unattainable.This paper proposes a technique based on blind separation to solve the co-channel interference problem,where separation of the mixed signal can be carried out by the particle filter(PF)algorithm.The experimental results show that the proposed method could achieve more accurate TDOA estimation.The measured data obtained by using the software radio platform at 915 MHz and 2 GHz respectively verify the effectiveness of the proposed method.

关键词： time difference of arrival(TDOA) co-channel interference blind separation particle filter(PF)

Enhanced Formaldehyde Gas Sensor based on Au-loaded ZnSnO_(3) Microspheres Nanocomposites

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Journal of Wuhan University of Technology(Materials Science) 2022年第6期37卷 1061-1065页

作者：何星欣陈洁应智花 ZHENG Xiaolong ZHENG Peng College of Electronics and Information Hangzhou Dianzi UniversityHangzhou 310018China

ZnSnO_(3) microspheres was compounded by hydrothermal method with sodium alginate(SA)as a crystal growth modifier,and the Au nanoparticles were decorated on the surface of ZnSnO_(3) microspheres by simple solution method and heat treatment process.The structure and morphology of the prepared samples were characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).Under ultraviolet(UV)irradiation,the 0.2wt%Au/ZnSnO_(3)@4g/L SA sensor could detect HCHO and reached a good response of 18.8 at 20 ppm,which was three times higher than the ZnSnO_(3) in the absence of Au.This sensor also performed an outstanding linearity within 5-20 ppm HCHO and satisfied repeatability.Moreover,the possible mechanism of the influence of Au on gas sensitivity is also proposed.

关键词： ZnSnO_(3) Au HCHO gas sensor SA

Position Optimization for Mobile Relay Communications with Constrained Energy over a Whole Horizontal Plane

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China Communications 2023年第5期20卷 340-350页

作者： Haijun Tan Ning Xie Guangdong Key Laboratory of Intelligent information Processing College of Electronics and Information EngineeringShenzhen UniversityShenzhen 518060China

This paper concerns the position optimization problem of a mobile relay over a whole horizontal plane.This problem is important because the position of a mobile relay directly affects the end-to-end performance,e.g.,reliability,connectivity,and data rate.In this paper,we propose a new position optimization scheme of a mobile relay over a whole horizontal plane based on the one-bit feedback information from the destination node,which improves the performance over the prior scheme whose position of the mobile relay is optimized over a fixed orbit.In the proposed scheme,the mobile relay is equipped with merely one single onboard antenna.Moreover,no prior information about the positions of both the source node and the destination node is required.Thus,the proposed scheme can work at low network resources scenario,which is particularly suitable for mobile relay communication with constrained energy,e.g.,the communications in a disaster area where the infrastructure is heavily damaged,volcano monitoring,and wireless powered communication networking.According to the characteristics of the proposed scheme,we further design two heuristic implementations to calculate the optimal position of a mobile relay over a whole horizontal plane.The first implementation has better steady performance whereas the second implementation has better convergence speed.We implement the proposed scheme and conduct an extensive performance comparison between the proposed scheme and prior schemes to verify the advantages of the proposed scheme.

关键词： mobile relay position optimization one bit feedback information whole horizontal plane energy constrained

Bayesian neural network enhancing reliability against conductance drift for memristor neural networks

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Science China(information Sciences) 2021年第6期64卷 100-111页

作者： Yue ZHOU Xiaofang HU Lidan WANG Shukai DUAN College of Electronics and Information Engineering Southwest University college of Artificial Intelligence Southwest University

The hardware implementation of neural networks based on memristor crossbar array provides a promising paradigm for neuromorphic computing. However, the existence of memristor conductance drift harms the reliability of the deployed neural network, which seriously hinders the practical application of memristor-based neuromorphic computing. In this paper, the impact of different types of conductance drift on the weight realized by memristors is investigated and analyzed. Then, utilizing the weight uncertainty introduced by conductance drift, we propose a weight optimization method based on the Bayesian neural network, which can greatly improve the network performance. Furthermore, an ensemble approach is proposed to enhance network reliability without increasing training cost or crossbar array resources. Finally, the effectiveness of the proposed scheme is verified through a series of experiments. In addition, the proposed scheme can be easily integrated into the implementation of neuromorphic computing, which can provide a better guarantee for its large-scale application.

关键词： conductance drift neuromorphic computing Bayesian neural network memristor crossbar array network reliability

Modeling and experimental studies of a side band power re-injection locked magnetron

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Chinese Physics B 2016年第12期25卷 492-498页

作者：叶文军张益袁萍朱铧丞黄卡玛杨阳 College of Electronics and Information Engineering Sichuan University

A side band power re-injection locked （SBPRIL） magnetron is presented in this paper. A tuning stub is placed between the external injection locked （EIL） magnetron and the circulator. Side band power of the EIL magnetron is reflected back to the magnetron. The reflected side band power is reused and pulled back to the central frequency. A phase-locking model is developed from circuit theory to explain the process of reuse of side band power in SBPRIL magnetron. Theoretical analysis proves that the side band power is pulled back to the central frequency of the SBPRIL magnetron, then the amplitude of the RF voltage increases and the phase noise performance is improved. Particle-in-cell （PIC） simulation of a 10-vane continuous wave （CW） magnetron model is presented. Computer simulation predicts that the frequency spectrum＇s peak of the SBPRIL magnetron has an increase of 3.25 dB compared with the free running magnetron. The phase noise performance at the side band offset reduces 12.05 dB for the SBPRIL magnetron. Besides, the SBPRIL magnetron experiment is presented. Experimental results show that the spectrum peak rises by 14.29% for SBPRIL magnetron compared with the free running magnetron. The phase noise reduces more than 25 dB at 45-kHz offset compared with the free running magnetron.

关键词： magnetrons injection locking tuning stub phase noise