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Breakdown of effective-medium theory by a photonic spin Hall effect

Science China(Physics,Mechanics & Astronomy) 2023年第11期66卷 145-154页

作者： Shuaijie Yuan Xinxing Zhou Yu Chen Yuhan Zhong Lijuan Sheng Hao Hu Hongsheng Chen Ido Kaminer Xiao Lin Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Synergetic Innovation Center for Quantum Effects and ApplicationsSchool of Physics and ElectronicsHunan Normal UniversityChangsha410081China International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong ProvinceInstitute of Microscale OptoelectronicsShenzhen UniversityShenzhen518060China Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and InstrumentationZJU-Hangzhou Global Scientific and Technological Innovation CenterZhejiang UniversityHangzhou310027China International Joint Innovation Center Electromagnetics Academy at Zhejiang UniversityZhejiang UniversityHaining314400China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore639798Singapore Key Laboratory of Radar Imaging and Microwave Photonics Ministry of EducationCollege of Electronic and Information EngineeringNanjing University of Aeronautics and AstronauticsNanjing211106China Key Laboratory of Advanced Micro/Nano Electronic Devices&Smart Systems of Zhejiang Jinhua Institute of Zhejiang UniversityZhejiang UniversityJinhua321099China Shaoxing Institute of Zhejiang University Zhejiang UniversityShaoxing312000China Department of Electrical Engineering Technion-Israel Institute of TechnologyHaifa32000Israel

Effective-medium theory pertains to the theoretical modelling of homogenization,which aims to replace an inhomogeneous structure of subwavelength-scale constituents with a homogeneous effective *** effective-medium theory is fundamental to various realms,including electromagnetics and material science,since it can largely decrease the complexity in the exploration of light-matter interactions by providing simple acceptable ***,the effective-medium theory is thought to be applicable to any all-dielectric system with deep-subwavelength constituents,under the condition that the effective medium does not have a critical angle,at which the total internal reflection *** we reveal a fundamental breakdown of the effective-medium theory that can be applied in very general conditions:showing it for deep-subwavelength all-dielectric multilayers even without a critical *** finding relies on an exotic photonic spin Hall effect,which is shown to be ultrasensitive to the stacking order of deep-subwavelength dielectric layers,since the spin-orbit interaction of light is dependent on slight phase accumulations during the wave *** results indicate that the photonic spin Hall effect could provide a promising and powerful tool for measuring structural defects for all-dielectric systems even in the extreme nanometer scale.

关键词： photonic spin Hall effect effective-medium theory spin-orbit interaction of light

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Extended-localized transition in diffusive quasicrystals

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Physical Review Applied 2024年第6期21卷 064035-064035页

作者： Zhoufei Liu Pei-Chao Cao Ying Li Jiping Huang Department of Physics State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center International Joint Innovation Center Key Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang The Electromagnetics Academy of Zhejiang University Shaoxing Institute of Zhejiang University

Compared with periodic systems, quasicrystals without translational invariance exhibit unexpected localization properties. The extended-localized transition in quasicrystals has been observed in both quantum and classical wave systems. However, its manifestation in diffusion systems, which serve as novel platforms for exploring phases of matter in condensed-matter physics, remains unexplored. Here we present an implementation of the extended-localized transition in a diffusive quasicrystal based on a coupled-ring chain structure. By modulating the thermal conductivities of the rings, we obtain the diffusive one-dimensional Aubry-André-Harper (AAH) model, which exhibits an extended-localized transition. Thanks to the ring-shaped chain, we clearly demonstrate the extended-localized transition under uniform excitation through temperature-field simulations. For the localized state, the temperature field clearly demonstrates a phenomenon of multiple localization centers, which has no counterpart in wave systems. We also quantitatively investigate the temperature evolution and size effect of this transition. Furthermore, local excitation is used to demonstrate the temperature field for both the extended state and the localized state. Besides, we implement the non-Hermitian diffusive AAH model by rotating the rings, whose temperature field shows a phenomenon of moving multiple localization centers in the localized phase. Finally, we give experimental suggestions for the diffusive AAH model and propose a potential application named the “double-trace distributed generator.” Our results should facilitate the design of flexible thermal devices and efficient heat management.

关键词： Anderson localization Diffusion Heat transfer Skin effect Thermoelectric effects Disordered systems Non-Hermitian systems Quasicrystals

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Design of Wideband Electromagnetic Absorbers Based on Deep Learning

Design of Wideband Electromagnetic Absorbers Based on Deep L...

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Robotics, Intelligent Control and Artificial Intelligence (RICAI), International Conference on

作者： Wan Ji Yan Li Erping Li Key Laboratory of Electromagnetic Wave Information Technology and Metrology of Zhejiang Province China Jiliang University Zhejiang China Key Laboratory of Advanced Micro-Nano Electronic Devices & Smart Systems and Applications Zhejiang University Zhejiang China

ISBN: (数字)9798331541699

ISBN: (纸本)9798331541705

This paper presents a deep learning-based multilayer perceptron (MLP) neural network approach for the design and optimization of electromagnetic absorbers operating in the 20-30 GHz frequency range. This method offers significant advantages in terms of miniaturization and wide bandwidth. By training the MLP neural network, the absorber structure is automatically optimized within this frequency band. The predicted results are in strong agreement with full-wave simulation outcomes. The findings demonstrate that this approach effectively enhances absorber efficiency, providing a novel solution for electromagnetic compatibility and stealth technology applications.

关键词： Deep learning Training Design methodology Multilayer perceptrons Electromagnetic absorbers Electromagnetic compatibility Structural engineering Electromagnetics Biological neural networks Wideband

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Nonvolatile silicon photonics based on monolithic back-end-of-line integration phase-change-materials platform for optical neural networks

Nonvolatile silicon photonics based on monolithic back-end-o...

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2024 Applied Optics and Photonics China: AI in Optics and Photonics, AOPC 2024

作者： Xu, Kai Wei, Maoliang Tang, Bo Li, Junying Li, Lan Lin, Hongtao The State Key Lab of Brain-Machine Intelligence Key Laboratory of Micro-Nano Electronics and Smart System of Zhejiang Province College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China Institute of Microelectronics of the Chinese Academy of Sciences Beijing100029 China Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Hangzhou310024 China Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province School of Engineering Westlake University Zhejiang Hangzhou310030 China Institute of Advanced Technology Westlake Institute for Advanced Study Zhejiang Hangzhou310024 China

ISBN: (数字)9781510687943

ISBN: (纸本)9781510687936

Benefiting from high parallelism and low latency, photonic integrated circuits (PICs) constructed from on-chip building blocks with diverse functions have emerged as a promising technology in the realm of optical neural networks (ONN). Tunable components, through the utilization of physical mechanisms such as thermo-optic effect and free-carrier plasma dispersion effect, structural motion like microelectromechanical systems (MEMS), or material properties including liquid crystal and two-dimensional materials, play a pivotal role in enabling reconfigurability within PICs. Among these reconfiguration schemes, chalcogenide phase change materials (PCMs) based photonic devices have attracted extensive attention owing to their high energy efficiency and integration density brought by huge refractive index contrasts and nonvolatility of PCMs. However, this nonvolatile modulation method meets difficulty in scalability since the process flow of integrating PCMs into silicon photonics is insupportable in the foundries. Here, we demonstrated a back-end-of-line (BEOL) integration platform for the monolithic integration of PCMs into silicon photonic devices without modification in standard process design kits (PDK). This is achieved by fabricating a low-loss oxide trench to expose the waveguide core at the functional area from the top dielectric layer, with assistance from a silicon nitride etch stop layer. On this basis, integrated photonic devices with stable switching performance and repeatable multi-bit storage capability have been developed, possessing the potential for crucial blocks of PICs in ONN applications that require infrequent reconfiguration, such as hardware error correction before training and data storage in pre-trained models. © 2024 SPIE.

关键词： Silicon nitride

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Efficient evolution framework for chirality control in non-Hermitian systems with adiabaticity engineering

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Physical Review B 2024年第6期110卷 064308-064308页

作者： Dong Wang Wen-Xi Huang Bo Zhou Wenduo Yu Pei-Chao Cao Yu-Gui Peng Zheng-Yang Zhou Hongsheng Chen Xue-Feng Zhu Ying Li State Key Laboratory of Extreme Photonics and Instrumentation Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang International Joint Innovation Center The Electromagnetics Academy at Jinhua Institute of Zhejiang University Shaoxing Institute of Zhejiang University School of Physics and Innovation Institute Key Laboratory of Optical Field Manipulation of Zhejiang Province Department of Physics

The eigenvalue of a non-Hermitian Hamiltonian often forms a self-intersecting Riemann surface, leading to a unique mode conversion phenomenon when the Hamiltonian evolves along certain loop paths around an exceptional point (EP). However, two fundamental problems exist with the conventional scheme of EP encircling: the speed of mode conversion is restricted by the adiabatic requirement, and the chirality cannot be freely controlled. Here, we introduce a method which dynamically engineers the adiabaticity in the evolution of non-Hermitian Hamiltonians that allows for both chiral and nonchiral mode conversion on the same path. Our method is based on quantifying and controlling the instantaneous adiabaticity, allowing for nonuniform evolution throughout the entire path. We apply our method into the microwave waveguide system and by optimizing the distributed adiabaticity along the evolution loop, we achieve the same quality of mode conversion as conventional quasiadiabatic evolution in only one-fourth of the time. Our approach provides an on-demand solution to address the speed and chirality challenges associated with EP encircling, which does not depend on specific model. It also facilitates the dynamic manipulation and regulation of nonadiabatic processes, thereby accelerating the operation and allowing for a selection among various mode conversion patterns.

关键词： Photonics Non-Hermitian systems PT-symmetry

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Ultrawideband chromatic aberration-free meta-mirrors

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advanced Photonics 2021年第1期3卷 47-56页

作者： Tong Cai Shiwei Tang Bin Zheng Guangming Wang Wenye Ji Chao Qian Zuojia Wang Erping Li Hongsheng Chena Zhejiang University College of Information Science and Electronic EngineeringInterdisciplinary Center for Quantum InformationState Key Laboratory of Modern Optical InstrumentationHangzhouChina Air Force Engineering University Air and Missile Defend CollegeXi’anChina Zhejiang University ZJU-Hangzhou Global Science and Technology Innovation CenterKey Laboratory of Advanced Micro/Nano Electronic Devices and Smart Systems of ZhejiangHangzhouChina Ningbo University Department of PhysicsFaculty of ScienceNingboChina

Chromatic aberration-free meta-devices(e.g.,achromatic meta-devices and abnormal chromatic meta-devices)play an essential role in modern science and ***,current efforts suffer the issues of low efficiency,narrow operating band,and limited wavefront manipulation *** propose a general strategy to design chromatic aberration-free meta-devices with high-efficiency and ultrabroadband properties,which is realized by satisfying the key criteria of desirable phase dispersion and high reflection amplitudes at the target frequency *** phase dispersion is tuned successfully based on a multiresonant Lorentz model,and high reflection is guaranteed by the presence of the metallic *** proof of the concept,two microwave meta-devices are designed,fabricated,and experimentally *** achromatic meta-mirror is proposed within 8 to 12 GHz,and another abnormal chromatic meta-mirror can tune the reflection angle as a linear *** meta-mirrors exhibit very high efficiencies(85%to 94%in the frequency band).Our findings open a door to realize chromatic aberration-free meta-devices with high efficiency and wideband properties and stimulate the realizations of chromatic aberration-free metadevices with other functionalities or working at higher frequency.

关键词： chromatic aberration-free meta-devices ultrabroadband metasurface phase and dispersion control multiresonant Lorentz model

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Coupling Path Identification of Conducted EMI in a High-Voltage Discharging Circuit Using Near-Field Scanning

Coupling Path Identification of Conducted EMI in a High-Volt...

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International Conference on microwave and Millimeter Wave Technology Proceedings

作者： Yu-Ting Xie Ling Zhang Jun-Hui Chen Da Li Zhen-Zhong Yang Er-Ping Li The Zhejiang Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems and Applications College of Information Science and Electronic Engineering Zhejiang University Hangzhou China Institute of Electronic Engineering China Academy of Engineering Physics Mianyang China

Electromagnetic interference (EMI) problems are common and can severely affect the normal function of high-voltage discharge circuits. This paper investigates the EMI issue in a dual-channel high-voltage discharge system, where the high-voltage discharging current of one circuit causes the false triggering of the other low-voltage triggering circuit. To effectively analyze the EMI coupling path, the near-field scanning (NFS) technique is adopted to capture and visualize the current flow path in the discharging process. A useful subtraction method is proposed to eliminate the radiated EMI from the high-voltage discharging current and better visualize the conducted EMI current. According to the NFS results after the subtraction process, the conducted EMI current coupling path can be straightforwardly obtained, and the corresponding mitigation approaches are demonstrated to solve the EMI problem effectively.

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A Novel Frequency Selective Surface Applied for EMI Suppression in Integrated Circuit Package

A Novel Frequency Selective Surface Applied for EMI Suppress...

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Workshop on Electromagnetic Compatibility of Integrated Circuits (EMC Compo)

作者： Panpan Zuo Hang Jin Tianwu Li Er-Ping Li School of Electronics and Information Engineering Hebei University of Technology Tianjin China Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems and Applications Zhejiang University Hangzhou China

Aiming on 10 GHz excessive radiation problem in IC package, a novel frequency selective surface (FSS) design is proposed in this paper. It is an ultrathin structure with only 0.0067λ 0 thickness, with a good stopband centered at 10 GHz. The electromagnetic interference (EMI) reduction performance is tested on a patch antenna which works at 10 GHz. The simulation shows the electric field radiation is suppressed by 8 dB μV/m at 10 GHz.

关键词： Electromagnetic compatibility Conferences Integrated circuits Electromagnetic interference Frequency selective surfaces Simulation

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Realizing transmitted metasurface cloak by a tandem neural network

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Photonics Research 2021年第5期9卷 I0062-I0068页

作者： ZHENG ZHEN CHAO QIAN YUETIAN JIA ZHIXIANG FAN RAN HAO TONG CAI BIN ZHENG HONGSHENG CHEN ERPING 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 Laboratory of Advanced Micro/Nano Electronic Devices&Smart Systems of ZhejiangZhejiang UniversityHangzhou 310027China International Joint Innovation Center ZJU-UIUC Institute Zhejiang UniversityHaining 314400China College of Optical and Electronic Technology China Jiliang UniversityHangzhou 310018China

Being invisible at will has been a long-standing dream for centuries, epitomized by numerous legends;humans have never stopped their exploration steps to realize this dream. Recent years have witnessed a breakthrough in this search due to the advent of transformation optics, metamaterials, and metasurfaces. However, the previous metasurface cloaks typically work in a reflection manner that relies on a high-reflection background, thus limiting the applications. Here, we propose an easy yet viable approach to realize the transmitted metasurface cloak, just composed of two planar metasurfaces to hide an object inside, such as a cat. To tackle the hard-to-converge issue caused by the nonuniqueness phenomenon, we deploy a tandem neural network(T-NN) to efficiently streamline the inverse design. Once pretrained, the T-NN can work for a customer-desired electromagnetic response in one single forward computation, saving a great amount of time. Our work opens a new avenue to realize a transparent invisibility cloak, and the tandem-NN can also inspire the inverse design of other metamaterials and photonics.

关键词： inverse uniqueness breakthrough

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Metasurface tessellation for reconfigurable electromagnetic scattering

arXiv

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arXiv 2020年

作者： Kong, Xiangdong Niu, Chuanning Zhao, Jia Wang, Zuojia School of Information Science and Engineering Shandong University Qingdao266237 China Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Electromagnetics Academy at Zhejiang University Zhejiang University Hangzhou310027 China

Metasurfaces have attracted significant research interest owing to their unprecedented control over the spatial distributions of electromagnetic fields. Herein we propose the concept of metasurface tessellation to achieve reconfigurable scattering functions. Square meta-tiles, composed of identical structures, are arranged to fill a surface. The electromagnetic scattering of the tiled surface is determined by the orientation distribution of the meta-tiles. We present three typical cases of meta-tiles consisting of binary elements to realize several distinct scattering patterns. This study provides an alternative method to build reconfigurable and multi-functional metasurface devices without external stimuli and complicated fabrication. Copyright © 2020, The Authors. All rights reserved.

关键词： Electromagnetic wave scattering

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