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Optical pulse processor based on achromatic time lens assisted by compound phase modulation

Optics Express 2025年第10期33卷 20754-20766页

作者： Liu, Huabei Xie, Qijie Ma, Chunyang Na, Quanxin Wang, Chaopeng Zuo, Guomeng Shi, Xiaobin Du, Jiangbing Wang, Lei Shao, Liyang Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen518055 China Peng Cheng Laboratory Shenzhen518055 China State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China

The time-lens based optical pulse processors have been widely applied in ultrafast optical processing and quantum optics. Conventionally, the time-lens systems used to adopt a sinusoidal waveform to approximate quadratic temporal phase modulation. It inevitably restricts the duration of a linear chirp, and thus limiting the temporal aperture to realize perfect Fourier transform. In this paper, we propose what we believe to be a novel achromatic time lens to expand the temporal aperture by using compound phase modulation. The achromatic time lens first compresses an optical pulse via a traditional time lens, and then introduces a linear chirp over the pulse duration by applying compound waveform consisted of the weighted fundamental and second harmonics. Numerical results proved that the synthesized linear chirp can be maintained over the pulse duration, when the duty cycle of the incident pulse increased from 15% to 72%. It indicates the effective temporal aperture to be expanded significantly. Experimentally, we have applied the achromatic time lens system to process a Gaussian pulse without distorting the pulse shape. The pulse width is compressed from 34 ps to 2.2 ps, while the spectral bandwidth is broadened from 0.32 nm to 1.6 nm. Both the temporal waveform and spectral envelope are maintained. The achromatic time lens scheme exhibits potential integration for supporting on-chip pulse processing with large time aperture. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Quantum optics

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Grid Forming Converters in Renewable Energy Sources Dominated Power Grid:Control Strategy,Stability,Application,and Challenges

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Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1239-1256页

作者： Haobo Zhang Wang Xiang Weixing Lin Jinyu Wen State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology TBEA Sunoasis Company Ltd. the State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology

The renewable energy sources(RESs)dominated power grid is an envisaged infrastructure of the future power system,where the commonly used grid following(GFL)control for grid-tied converters suffers from lacking grid support capability,low stability,***,emerging grid forming(GFM)control methods have been proposed to improve the dynamic performance and stability of grid-tied *** paper reviews existing GFM control methods for the grid-tied converters and compares them in terms of control structure,grid support capability,fault current limiting,and *** the impact of fault current limiting strategies,a comprehensive transient stability analysis is *** addition,this paper explores the typical applications of GFM converters,such as AC microgrid and offshore wind farm high-voltage direct current(OWF-HVDC)integration ***,the challenges to the GFM converters in future applications are discussed.

关键词： Grid following(GFL)control grid forming(GFM)control high-voltage direct current(HVDC) microgrid renewable energy small-signal stability transient stability

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Dual-Band Low-Profile Hybrid Antenna for Bidirectional Radiation

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IEEE Antennas and Wireless Propagation Letters 2025年

作者： Liu, Wenqing Li, Shufang Chen, Lijie Zhang, Chen Qu, Meijun Deng, Li Beijing University of Posts and Telecommunications School of Information and Communication Engineering Beijing100871 China China Ship Development and Design Center National Key Laboratory of Electromagnetic Effect and Security on Marine Equipment Wuhan430000 China Tianjin University of Technology and Education Tianjin300000 China Communication University of China State Key Laboratory of Media Convergence and Communication State Key Laboratory of Media Convergence and Communication School of Information and Communication Engineering Beijing100024 China

This paper presents a novel dual-band, low-profile hybrid folded antenna capable of generating bidirectional independent beams. The proposed design operates as a liked-folded reflectarray antenna at the low band, producing x-polarized high-gain beams in the lower hemisphere, and as a folded transmitarray antenna at the high band, generating y-polarized high-gain beams in the upper hemisphere. A prototype of the dual-band hybrid folded antenna was designed, fabricated, and measured. Measurement results show a y-polarized beam in the upper hemisphere, with a maximum gain of 31.2 dBi at 29 GHz, a peak aperture efficiency of 35.5%, and a 3-dB gain bandwidth of 8.2%. Simultaneously, an x-polarized beam is generated in the lower hemisphere, exhibiting a maximum gain of 22.9 dBi at 12.7 GHz, a peak aperture efficiency of 28.9%, and a 3-dB gain bandwidth of 26.3%. The proposed antenna retains the low-profile and high-gain advantages of traditional folded antennas, addressing space utilization limitations, effectively extending the conventional unidirectional dual-band folded structure to support bidirectional operation. © 2002-2011 IEEE.

关键词： Reflection

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f-p-d coupling-induced bonding covalency boosts C–C coupling in electrocatalytic CO2 reduction over Er–O–Cu sites

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Journal of Energy Chemistry 2025年 108卷 239-245页

作者： Wang, Maoyin Huang, Yuhang Song, Lu Wei, Ruilin Hao, Shuya Liu, Zhengzheng Hu, Cejun Li, Bin Lv, Ximeng Yuan, Pei Zheng, Gengfeng Laboratory of Advanced Materials State Key Laboratory of Porous Materials for Separation and Conversion Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai Shanghai200438 China School of Materials Science and Engineering Fuzhou University Fujian Fuzhou350108 China College of Materials Science and Engineering Qingdao University of Science and Technology Shandong Qingdao266042 China

The copper-based electrocatalysts feature attractive potentials of converting CO2 into multi-carbon (C2+) products, while the instability of Cu–O often induces the reduction of Cu+/Cu0 catalytic sites at the cathode and refrains the capability of stable electrolysis especially at high powers. In this work, we developed an Erbium (Er) oxide-modified Cu (Er–O–Cu) catalyst with enhanced covalency of Cu–O and more stable active sites. The f-p-d coupling strengthens the covalency of Cu–O, and the stability of Cu+ sites under electroreduction condition is critical for promoting the C–C coupling and improving the C2+ product selectivity. As a result, the Er–O–Cu sites exhibited a high Faradaic efficiency of C2+ products (FEC2+) of 86 % at 2200 mA cm−2, and a peak partial current density of |jC2+| of 1900 mA cm−2, comparable to the best reported values for the CO2-to-C2+ electroreduction. The CO2 electrolysis by the Er–O–Cu sites was further scaled up to 100 cm2 to achieve high-power (∼200 W) electrolysis with ethylene production rate of 16 mL min−1. © 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences

关键词： Electrolytic reduction

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High efficiency grating coupler on thin-film lithium niobate for visible light

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Optics Letters 2025年第10期50卷 3361-3364页

作者： Xing, Xinke Li, Xingjie Chen, Kaixuan Liu, Liu Guo, Changjian Guangdong Provincial Key Laboratory of Optical Information Materials and Technology South China Academy of Advanced Optoelectronics South China Normal University Higher-Education Mega-Center Sci. Bldg. No. 5 Guangzhou510006 China National Center for International Research on Green Optoelectronics South China Normal University Guangzhou510006 China Guangdong Engineering Research Centre of Optoelectronic Intelligent Information Perception South China Normal University Guangzhou510006 China State Key Laboratory of Extreme Photonics and Instrumentation College of Optical Science and Engineering International Research Center for Advanced Photonics Zijingang Campus Zhejiang University East Bldg. No. 5 Hangzhou310058 China

This work demonstrates high-efficiency grating couplers (GCs) designed for single-mode fiber coupling in the visible spectrum (centered at 532 nm) on an X-cut thin-film lithium niobate (TFLN) platform. By systematically optimizing the device architecture, the lithium niobate (LN) layer thickness was reduced to 150 nm, effectively enhancing coupling efficiency (CE). A hybrid optimization approach, combining commercial finite-difference time-domain (FDTD) simulations with a particle swarm optimization (PSO) algorithm, was employed to determine the optimal geometric parameters. This strategy yielded a simulated CE of 65% (−1.8 dB loss for non-uniform GC) and a measured CE of 45.2% (−3.45 dB loss for uniform GC). These results represent the highest, to the best of our knowledge, reported CE in the visible band for TFLN-based GCs. The demonstrated high-performance GC configuration serves as a critical photonic component for advancing integrated optical systems in visible-light communications, quantum photonic processing, and precision frequency metrology applications. © 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： Particle swarm optimization (PSO)

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Effect of Cu and Mo Alloying on Microstructure and Molten Salt Corrosion Resistance of 347H Stainless Steel

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Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and engineering 2025年第4期54卷 862-870页

作者： Yu, Zhiqi Zhao, Yanchun Liu, Tianzeng Feng, Li Ma, Huwen Li, Jucang Pan, Jixiang State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals School of Materials Science and Engineering Lanzhou University of Technology Lanzhou730050 China Gansu Jiu Steel Group Hongxing Iron & Steel Co. Ltd Jiayuguan735100 China

A static corrosion experiment of 347H stainless steel alloyed with elements Cu and Mo was carried out in a nitrate molten salt (60% NaNO3+40% KNO3) at 565 °C for 720 h. The effects of elements Cu and Mo on the corrosion resistance of 347H stainless steel in molten salt were investigated by analyzing the phase composition, microstructure and chemical composition of the corrosion products. The results show that the grain refinement induced by element Mo imparts the stainless steel with optimal corrosion resistance at a medium grain size. Furthermore, the formation of MoC significantly enhances the intergranular corrosion resistance of the stainless steel. The stainless steel exhibits uniform corrosion in the nitrate solution. The corrosion layer displays a dual-layer structure, and the corrosion products protecting matrix are present in both the inner and outer layers. The outer layer consists of a mixture of Fe oxides (Fe2O3, Fe3O4), NaFeO2, and a minor amount of MgFe2O4. Conversely, the inner layer is primarily composed of a spinel layer (FeCr2O4, MgCr2O4) and a thin Cu2O layer. The oxidation of Cu in the inner layer leads to the formation of a dense Cu2O layer, effectively impeding O2- plasma infiltration into the matrix. Copyright © 2025, Northwest Institute for Nonferrous Metal Research. Published by Science Press. All rights reserved.

关键词： Grain refinement

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Photonic axion insulator

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Science (New York, N.Y.) 2025年第6730期387卷 162-166页

作者： Liu, Gui-Geng Mandal, Subhaskar Xi, Xiang Wang, Qiang Devescovi, Chiara Morales-Pérez, Antonio Wang, Ziyao Yang, Linyun Banerjee, Rimi Long, Yang Meng, Yan Zhou, Peiheng Gao, Zhen Chong, Yidong García-Etxarri, Aitzol Vergniory, Maia G. Zhang, Baile Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore Research Center for Industries of the Future Department of Electronic and Information Engineering School of Engineering Westlake University Hangzhou China School of Electrical Engineering and Intelligentization Dongguan University of Technology Dongguan China National Laboratory of Solid State Microstructures School of Physics Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing China Donostia International Physics Center Donostia-San Sebastian Spain Institute for Theoretical Physics ETH Zurich Zurich Switzerland Material and Applied Physics Department University of the Basque Country (UPV/EHU) Donostia-San Sebastián Spain Department of Electronic and Electrical Engineering Southern University of Science and Technology Shenzhen China National Engineering Research Center of Electromagnetic Radiation Control Materials Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education University of Electronic Science and Technology of China Chengdu China State Key Laboratory of Optical Fiber and Cable Manufacture Technology Department of Electronic and Electrical Engineering Guangdong Key Laboratory of Integrated Optoelectronics Intellisense Southern University of Science and Technology Shenzhen China Centre for Disruptive Photonic Technologies Photonics Institute Nanyang Technological University Singapore IKERBASQUE Basque Foundation for Science Bilbao Spain Max Planck Institute for Chemical Physics of Solids Dresden Germany Département de Physique et Institut Quantique Université de Sherbrooke Sherbrooke Canada

Axions, hypothetical elementary particles that remain undetectable in nature, can arise as quasiparticles in three-dimensional crystals known as axion insulators. Previous implementations of axion insulators have largely been limited to two-dimensional systems, leaving their topological properties in three dimensions unexplored in experiment. Here, we realize an axion insulator in a three-dimensional photonic crystal and probe its topological properties. Demonstrated features include half-quantized Chern numbers on each surface that resembles a fractional Chern insulator, unidirectional chiral hinge states forming topological transport in three dimensions, and arithmetic operations between fractional and integer Chern numbers. Our work experimentally establishes the axion insulator as a three-dimensional topological phase of matter and enables chiral states to form complex, unidirectional three-dimensional networks through braiding.

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Spatial-temporal dual-stream fusion network with embedded knowledge: A process-generalized framework for tool wear monitoring

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Journal of Manufacturing Systems 2025年 81卷 189-207页

作者： Chen, Zhixiang Zhang, Jin Qin, Fengze Tao, Guibao Li, Duo Cao, Huajun College of Mechanical and Vehicle Engineering Chongqing University Chongqing400044 China State Key Laboratory of Mechanical Transmissions for advanced equipment Chongqing University Chongqing400044 China Center of Precision Engineering School of Mechatronics Engineering Harbin Institute of Technology Harbin150001 China

As a pivotal technology in intelligent computer numerical control (CNC) systems, tool wearing monitoring (TWM) significantly influences machining stability, product quality, and production efficiency. However, the complexity and randomness of the tool wear process pose significant challenges to traditional single-model methods. These methods often struggle to capture diverse data patterns, leading to low accuracy and poor processing generalization. This study proposes a Spatial-Temporal Dual Stream Fusion Network (STDSFnet) with embedded knowledge. The framework establishes strong correlations between multi-modal sensor data and tool wear states. The methodology consists of three key steps: (1) applying Spearman correlation analysis to select sensitive feature vectors, which helps reduce transient signal interference;(2) developing a dual-stream network to extract spatial and temporal wear-related information;and (3) integrating coordinated attention mechanisms and feature fusion modules to enhance the feature representation, thereby improve the TWM accuracy and processing generalization. Besides, to ensure that the trend of TWM results conforms to the actual wear pattern, domain knowledge is introduced to improve the reliability and interpretability of monitoring results. Experiments validate the effectiveness of STDSFnet on block-shaped stainless-steel workpieces and carbon fiber-reinforced polymer (CFRP) machining scenarios. Compared to baseline methods, STDSFnet reduces RMSE by 38.94 %–62.04 %, decreases MAE by 43.64 %–61.70 %, and improves R² by 4.96 %–28.59 %. These results confirm that spatial-temporal fusion with deep ensembles significantly boosts TWM accuracy and reliability. © 2025 The Society of Manufacturing Engineers

关键词： Computer control

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Thermodynamic analysis of C2H4/C2H6 separation based on silver-based containing ionic liquid

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Chemical engineering Science 2025年 315卷

作者： Yang, Peng Liu, Wei Wang, Zongxu Dong, Haifeng Ren, Mengyu Li, Dan Cai, Aizi Jin, Xiao Wang, Junnan Fang, Yanxiong Guangzhou Key Lab Clean Transport Energy Chemistry School of Light Industry & Chemical Engineering Guangdong University of Technology Guangzhou510006 China CAS Key Laboratory of Green Process and Engineering State Key Laboratory of Mesoscience and Engineering Beijing Key Laboratory of Ionic Liquids Clean Process Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China Huizhou Institute of Green Energy and Advanced Materials Guangdong Huizhou516081 China

Low-energy C2H4/C2H6 separation processes based on ionic liquids are a hot topic of research. Among them, silver-based containing ionic liquids (Ag-ILs) exhibit excellent separation performance. The absorption thermodynamic of this system is crucial for the development of new processes. At 313.15 to 333.15 K, the solubility of C2H4 and C2H6 in Ag-ILs was measured. Combined with the fitting of the solubility of the "deactivation model", the Henry's constant (H) and the reaction equilibrium constant (K) were obtained, which accurately described the absorption behavior of C2H4 in Ag-IL, and the relationship between the enthalpy of absorption and the solubility was correlated. Furthermore, combined with quantum chemical computation, the absorption mechanism was revealed that complexation reaction led to higher solubility of C2H4, and the enthalpy of the reaction is the main driving force. This paper provides theoretical support for the industrial research on the C2H4/C2H6 separation by Ag-IL. © 2025

关键词： Enthalpy

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Interfacial Structure and Mechanical Properties of Diamond/Copper Joint Brazed by Ag-Cu-In-Ti Low-Temperature Brazing Filler

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稀有金属材料与工程 2025年第2期54卷 301-310页

作者： Pan Yufan Liang Jiabin Nie Jialong Liu Xin Sun Huawei Chang Yunfeng Li Huaxin Lu Chuanyang Xu Dong Wang Xingxing Yang Yang Yang Jianguo He Yanming College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310023China China Energy Engineering Group Zhejiang Thermal Power Construction Co. LtdHangzhou 311200China China Academy of Machinery Zhengzhou Research Institute of Mechanical Engineering Co. LtdZhengzhou 450052China State Key Laboratory of Advanced Brazing Filler Metals and Technology Zhengzhou 450052China School of Materials Science and Engineering Anhui Polytechnic UniversityWuhu 241000China Henan International Joint Laboratory of High-Efficiency Special Green Welding North China University of Water Resources and Electric PowerZhengzhou 450045China Zhejiang YaTong Advanced Materials Co. LtdHangzhou 310030China

Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were *** addition,the joint formation mechanism was discussed,and the correlation between joint microstructure and mechanical performance was *** show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on *** the brazing temperature is 750°C and the soaking time is 10 min,a uniformly dense braze seam with excellent metallurgical bonding can be obtained,and its average joint shear strength reaches 322 *** lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.

关键词： diamond microwave window vacuum brazing Ag-Cu-In-Ti microstructure mechanical properties

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