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Experimental realization of valley vortex states in water wave crystals

Science Bulletin 2025年第7期70卷 1034-1037页

作者： Zijian Qin Qiaolu Chen Lian Shen Yihao Yang Hongsheng Chen Huaping Wang Key Laboratory of Ocean Observation-Imaging Testbed of Zhejiang Province Ocean CollegeZhejiang UniversityHangzhou 310058China State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation CenterZhejiang UniversityHangzhou 310027China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical InstrumentationCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou 310027China Key Lab of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang Jinhua Institute of Zhejiang UniversityZhejiang UniversityJinhua 321099China Shaoxing Institute of Zhejiang University Zhejiang UniversityShaoxing 312000China International Joint Innovation Center The Electromagnetics Academy at Zhejiang UniversityZhejiang UniversityHaining 314400China

The valley degree of freedom(DoF)plays a crucial role in valleytronics,paralleling the spin DoF in spintronics,and serves as a novel conduit for information and *** momentum space,valley DoF is characterized by discrete energy extremal states,which are present in conventional semiconductors and twodimensional(2D)crystal *** wave behaviors in periodic structures allow for the application of valley dispersion relations to wave systems,including optics[1],acoustics[2,3],and water waves[4].When the wavelength is comparable to the period of an artificial crystal structure,classical waves experience strong Bragg scattering,resulting in a band gap and new propagation *** to their macroscopic features and controllable geometric symmetry,these classical wave systems have become an ideal platform for studying topological *** progress has been made in classical wave systems,conclusive evidence of topological valley states in water waves—a typical classical wave system—has not yet been obtained.

关键词： spin dof valley dispersion relations valley degree freedom dof plays discrete energy extremal stateswhich valley vortex states wave behaviors wave systemsincluding conventional semiconductors

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Photonic antiferromagnetic topological insulator with a single surface Dirac cone

arXiv

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arXiv 2025年

作者： Chen, Fujia Han, Ning Pu, Songyang Zhao, Rui Zhang, Li Chen, Qiaolu Hu, Yuze Tong, Mingyu Li, Wenhao Wu, Junyao Ren, Yudong Li, Xinrui Yin, Wenyan Chen, Hongsheng Zhang, Rui-Xing Yang, Yihao State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center The Electromagnetics Academy Zhejiang University Zhejiang University Haining314400 China Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua321099 China Department of Physics and Astronomy The University of Tennessee KnoxvilleTN37996 United States Department of Materials Science and Engineering The University of Tennessee KnoxvilleTN37996 United States

Antiferromagnetism, characterized by magnetic moments aligned in alternating directions with a vanished ensemble average, has garnered renewed interest for its potential applications in spintronics and axion dynamics. The synergy between antiferromagnetism and topology can lead to the emergence of an exotic topological phase unique to certain magnetic order, termed antiferromagnetic topological insulators (AF TIs). A hallmark signature of AF TIs is the presence of a single surface Dirac cone—a feature typically associated with strong three-dimensional (3D) topological insulators—only on certain symmetry-preserving crystal terminations. However, the direct observation of this phenomenon poses a significant challenge. Here, we have theoretically and experimentally discovered a 3D photonic AF TI hosting a single surface Dirac cone protected by the combined symmetry of time reversal and half-lattice translation. Conceptually, our setup can be viewed as a z-directional stack of two-dimensional Chern insulators, with adjacent layers oppositely magnetised to form a 3D type-A AF configuration. By measuring both bulk and surface states, we have directly observed the symmetry-protected gapless single-Dirac-cone surface state, which shows remarkable robustness against random magnetic disorders. Our work constitutes the first realisation of photonic AF TIs and photonic analogues of strong topological insulators, opening a new chapter for exploring novel topological photonic devices and phenomena that incorporate additional magnetic degrees of freedom. © 2025, CC BY-NC-SA.

关键词： Topological insulators

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Topologically protected edge states in time photonic crystals with chiral symmetry

arXiv

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arXiv 2025年

作者： Yang, Yukun Hu, Hao Liu, Liangliang Yang, Yihao Yu, Youxiu Long, Yang Zheng, Xuezhi Luo, Yu Li, Zhuo Garcia-Vidal, Francisco J. National Key Laboratory of Microwave Photonics College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Nanjing211106 China State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center The Electromagnetics Academy Zhejiang University Zhejiang University Haining314400 China Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua321099 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore Department of Electrical Engineering KU Leuven Leuven3001 Belgium Universidad Autónoma de Madrid MadridE-28049 Spain

Time photonic crystals are media in which their electromagnetic parameters are modulated periodically in time, showing promising applications in non-resonant lasers and particle accelerators, among others. Traditionally utilized to study space photonic crystals, topological band theory has also been translated recently to analyze time photonic crystals with time inversion symmetry, enabling the construction of the temporal version of topological edge states. However, temporal disorder can readily break time inversion symmetry in practice, hence likely destroying the edge states associated with this type of time photonic crystals. To overcome this limitation, here we propose a new class of time photonic crystals presenting chiral symmetry instead, whose edge states exhibit superior robustness over the time-reversal-symmetry-protected counterparts. Our time photonic crystal is equivalent to a temporal version of the Su-Schrieffer-Heeger model, and the chiral symmetry of this type of time photonic crystals quantizes the winding number defined in the Bloch frequency band. Remarkably, random temporal disorders do not impact the eigenfrequencies of these chiral-symmetry-protected edge states, while instead enhancing their temporal localizations. Our findings thus provide a promising paradigm to control field amplification with exceptional robustness as well as being a feasible platform to investigate various topological phases in time-varying media. Copyright © 2025, The Authors. All rights reserved.

关键词： Topology

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Temporal Neural Encoding Methods for Spiking Neural Networks 13

Temporal Neural Encoding Methods for Spiking Neural Networks

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13th Asia-Pacific International Symposium on Electromagnetic Compatibility and Technical Exhibition, APEMC 2022

作者： Chen, Quankun Li, Da Tao, Tuomin Ma, Hanzhi Li, Erping Zhejiang University The Zhejiang Key Lab. of Advanced Micro/Nano Electronic Devices Smart Systems and Applications Hangzhou China

ISBN: (数字)9781665416719

ISBN: (纸本)9781665416719

Spike neural networks (SNNs) have gained growing attention, and the temporal encoding methods for the signal input are also crucial. Among these encoding algorithms, a suitable and simple encoding method not only affects the performance of the SNNs but also relates to the expansion in hardware. Several high-performance and easily realized encoding algorithms are discussed in this paper. © 2022 IEEE.

关键词： Network coding

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A Miniaturized Absorber for Radiation Suppression in the Chip Package 7

A Miniaturized Absorber for Radiation Suppression in the Chi...

引用

7th IEEE International Symposium on Electromagnetic Compatibility, ISEMC 2023

作者： Lin, Chaolong Xing, Jiaqi Li, Da Li, Er-Ping Zhejiang University The Zhejiang Key Lab. of Advanced Micro/Nano Electronic Devices Smart Systems and Applications Hangzhou China

ISBN: (纸本)9798350333107

In this page, a miniaturized absorber with ultrawide absorption band is designed and applied for radiation leakage suppression in the chip package. The proposed unit is a double-layer structure with two patterned resistive films of ITO etched on top of the dielectric substrate. The patterned layer is composed of a meandering square ring and a centric circular patch which enhances the coupling within the unit and facilitates the miniaturization of the structure. The size of the unit is 0.08λL× 0.08λL(λL is the wavelength in the free space of the lowest absorption frequency). When the periodic boundary condition is set in the simulation, it shows a broad absorption band (S11-10dB) covering 23.8-40 GHz. This unit is then used as a square ring structure for radiation suppression in chip package which demonstrates a -10dB bandwidth within 25.5-39.5 GHz. © 2023 IEEE.

关键词： Dielectric materials

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A Novel 3-D Frequency Selective Surface With Ultrawide Passband and High Selectivity 11

A Novel 3-D Frequency Selective Surface With Ultrawide Passb...

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11th IEEE Asia-Pacific Conference on Antennas and Propagation, APCAP 2023 - Proceedings

作者： An, Xiaodong Xie, Jialong Li, Da Fan, Yudi Li, Erping Zhejiang University The Zhejiang Key Lab. of Advanced Micro/Nano Electronic Devices Smart Systems and Applications Hangzhou310000 China

ISBN: (纸本)9798350326277

In this paper, a novel 3-dimensional (3-D) frequency selective surface (FSS) structure with ultrawide passband and high selectivity is proposed. Compared to traditional two-dimensional (2-D) wideband structures, (3-D) structures offer enhanced selectivity but exhibit higher insertion loss in the passband. Moreover, three-dimensional structures are often more complex and challenging to manufacture. This paper proposes a simplified three-layer structure. When vertically incident, the FSS exhibits a -3 dB bandwidth of 8-18.4 GHz with a relative bandwidth of 78.7%. Additionally, it forms a stopband with a suppression level exceeding -10 dB within the frequency range of 0-5.2 GHz. In the TE mode, the FSS maintains excellent operational performance within an incident angle range of 0-40 degrees. © 2023 IEEE.

关键词： frequency selective surface passband wideband

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A knowledge-inherited learning for intelligent metasurface design and assembly

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Light(Science & Applications) 2023年第4期12卷 680-690页

作者： Yuetian Jia Chao Qian Zhixiang Fan Tong Cai Er-Ping Li Hongsheng Chen ZJU-UIUC Institute Interdisciplinary Center for Quantum InformationState Key Laboratory of Extreme Photonics and InstrumentationZhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab.of Advanced Micro/Nano Electronic Devices&Smart Systems of ZhejiangZhejiang UniversityHangzhou 310027China Jinhua Institute of Zhejiang University Zhejiang UniversityJinhua 321099China Air and Missile Defense College Air Force Engineering UniversityXi'an 710051China Shaoxing Institute of Zhejiang University zhejiang UniversityShaoxing321000China

Recent breakthroughs in deep learning have ushered in an essential tool for optics and photonics,recurring in various applications of material design,system optimization,and automation *** learning-enabled on-demand metasurface design has been the subject of extensive expansion,as it can alleviate the time-consuming,low-efficiency,and experience-orientated shortcomings in conventional numerical simulations and physics-based ***,collecting samples and training neural networks are fundamentally confined to predefined individual metamaterials and tend to fail for large problem *** by object-oriented C++programming,we propose a knowledge-inherited paradigm for multi-object and shape-unbound metasurface inverse *** inherited neural network carries knowledge from the"parent"metasurface and then is freely assembled to construct the"offspring"metasurface;such a process is as simple as building a container-type *** benchmark the paradigm by the free design of aperiodic and periodic metasurfaces,with accuracies that reach 86.7%.Furthermore,we present an intelligent origami metasurface to facilitate compatible and lightweight satellite communication *** work opens up a new avenue for automatic metasurface design and leverages the assemblability to broaden the adaptability of intelligent metadevices.

关键词： breakthrough consuming shortcomings

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Advection and Thermal Diode

引用

Chinese Physics Letters 2021年第3期38卷 22-28页

作者： Ying Li Jiaxin Li Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical InstrumentationCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab of Advanced Micro/Nano Electronic Devices&Smart Systems of ZhejiangZhejiang UniversityHangzhou 310027China International Joint Innovation Center Zhejiang UniversityHaining 314400China School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001China

We prove that under the condition of closed boundary to mass flux, pure advection is not a valid mechanism to make a practical thermal diode. Among the various designs of thermal diodes, many of them involve circulating fluid flow, such as in thermosyphons. However, those designs often employ natural convection, which is basically a nonlinear process. It thus remains unclear how the pure advection of temperature field induced by a decoupled velocity field influences the symmetry of heat transfer. Here we study three typical models with pure advection:one with open boundary, one with closed boundary at unsteady state, and one with closed boundary at steady state. It is shown that only the last model is practical, while it cannot become a thermal diode. Finally, a general proof is given for our claim by analyzing the diffusive reciprocity.

关键词： process. state. boundary

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A Novel Miniaturized Zigzag Hexagonal Frequency Selective Surface 11

A Novel Miniaturized Zigzag Hexagonal Frequency Selective Su...

引用

11th IEEE Asia-Pacific Conference on Antennas and Propagation, APCAP 2023 - Proceedings

作者： Xie, Jialong An, Xiaodong Li, Da Ma, Hanzhi Li, Er-Ping Zhejiang University The Zhejiang Key Lab. of Advanced Micro/Nano Electronic Devices Smart Systems and Applications College of Information Science and Electronic Engineering Hangzhou China

ISBN: (纸本)9798350326277

A novel miniaturized zigzag hexagonal frequency selective surface (FSS) element is proposed, where the structure has a dual-polarized angular stable passband. The FSS resonates at 4.0GHz, with a 3 dB passband spanning from 3.1 GHz to 4.72GHz, accommodating both transverse electric (TE) and transverse magnetic (TM) polarizations. Impressively, even at a 60° incidence angle, the shift in the transmission zero for the TE polarized wave is a mere 0.3%, demonstrating notable stability in terms of polarization and angular response. © 2023 IEEE.

关键词： frequency selective surface (FSS) high angle stability passband.

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Performing optical logic operations by a diffractive neural network

引用

Light(Science & Applications) 2020年第1期9卷 1448-1454页

作者： Chao Qian Xiao Lin Xiaobin Lin Jian Xu Yang Sun Erping Li Baile Zhang Hongsheng Chen Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical InstrumentationCollege of Information Science and Electronic EngineeringZhejiang University310027 HangzhouChina ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab.of Advanced Micro/Nano Electronic Devices&Smart Systems of ZhejiangZhejiang University310027 HangzhouChina Department of Electrical Engineering California Institute of TechnologyPasadenaCAUSA ZJU-UIUC Institute Zhejiang University310027 HangzhouChina Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore

Optical logic operations lie at the heart of optical computing,and they enable many applications such as ultrahighspeed information ***,the reported optical logic gates rely heavily on the precise control of input light signals,including their phase difference,polarization,and intensity and the size of the incident *** to the complexity and difficulty in these precise controls,the two output optical logic states may suffer from an inherent instability and a low contrast ratio of ***,the miniaturization of optical logic gates becomes difficult if the extra bulky apparatus for these controls is *** such,it is desirable to get rid of these complicated controls and to achieve full logic functionality in a compact photonic *** a goal remains ***,we introduce a simple yet universal design strategy,capable of using plane waves as the incident signal,to perform optical logic operations via a diffractive neural ***,the incident plane wave is first spatially encoded by a specific logic operation at the input layer and further decoded through the hidden layers,namely,a compound Huygens’*** is,the judiciously designed metasurface scatters the encoded light into one of two small designated areas at the output layer,which provides the information of output logic ***,after training of the diffractive neural network,all seven basic types of optical logic operations can be realized by the same *** a conceptual illustration,three logic operations(NOT,OR,and AND)are experimentally demonstrated at microwave frequencies.

关键词： surface operations precise

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