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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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Extended-localized transition in diffusive quasicrystals

arXiv

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arXiv 2022年

作者： Liu, Zhoufei Cao, Pei-Chao Li, Ying Huang, Jiping Fudan University Shanghai200438 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 Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang The Electromagnetics Academy of Zhejiang University Zhejiang University Haining314400 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing312000 China

Compared to 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 the implementation of the extended-localized transition in a diffusive quasicrystal based on the coupled ring chain structure. By modulating the thermal conductivities of 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 the uniform excitation through temperature field simulations. For the localized state, the temperature field clearly demonstrates a multiple localization centers phenomenon, which has no counterpart in wave systems. We also quantitatively investigate the temperature evolution and size effect of this transition. Furthermore, the local excitation has been adopted to demonstrate the temperature field for both the extended and localized states. Besides, we implement the non-Hermitian diffusive AAH model by rotating rings, whose temperature field shows a moving multiple localization centers phenomenon in the localized phase. Finally, we give the experimental suggestions for the diffusive AAH model and propose a potential application named as double-trace distributed generator. Our results can facilitate the design of flexible thermal devices and efficient heat management. © 2022, CC BY.

关键词： Temperature

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High-Speed Efficient On-Chip Electro-Optic Modulator Based on Midinfrared Hyperbolic Metamaterials

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Physical Review Applied 2021年第3期16卷 034002-034002页

作者： Dongdong Li Hongbin Ma Qiwei Zhan Jie Liao Wen-Yan Yin Hongsheng Chen Haoliang Qian Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Zhejiang University Hangzhou 310027 China International Joint Innovation Center ZJU-UIUC Institute Zhejiang University Haining 314400 China

Integrated modulators are key components for on-chip optical communication and information processing, which have become leading technologies in the current information-growth era. Hence, high-speed, efficient, and compact integrated modulators are in high demand. However, the current integrated midinfrared modulators meet these requirements with difficulty. Here, we present a high-speed and efficient on-chip electro-optic modulator based on midinfrared hyperbolic metamaterials using stacking of graphene and hexagonal boron nitride. The length of the modulation region is only 60 nm, which is integrated on a plasmonic waveguide composed of hyperbolic metamaterials. The maximum modulation depth is up to 30 dB, and the 3-dB modulation speed can reach up to 50 GHz, which is supported by a detailed study of a small-signal frequency-response model. Our work provides an alternative scheme for the design of modulators with the requirements of sub-100-nm integration and 50-GHz modulation speed or even beyond, which can be directly implemented into a two-dimensional-materials-based photonic integrated circuits platform.

关键词： Hyperbolic metamaterials Integrated optics nanophotonics Optoelectronics Plasmonics 2-dimensional systems devices Infrared techniques

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Observation of scale-free localized states induced by non-Hermitian defects

arXiv

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arXiv 2024年

作者： Xie, Xinrong Liang, Gan Ma, Fei Du, Yulin Peng, Yiwei Li, Erping Chen, Hongsheng Li, Linhu Gao, Fei Xue, Haoran Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China Zhuhai519082 China Department of Physics The Chinese University of Hong Kong Shatin Hong Kong 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 Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing312000 China

Wave localization is a fundamental phenomenon that appears universally in both natural materials and artificial structures and plays a crucial role in understanding the various physical properties of a system. Usually, a localized state has an exponential profile with a localization length independent of the system size. Here, we experimentally demonstrate a new class of localized states called scale-free localized states, which has an unfixed localization length scaling linearly with the system size. Using circuit lattices, we observe that a non-Hermitian defect added to a Hermitian lattice induces an extensive number of states with scale-free localization. Furthermore, we demonstrate that, in a lattice with a parity-time-symmetric non-Hermitian defect, the scale-free localization emerges because of spontaneous parity-time symmetry breaking. Our results uncover a new type of localized states and extend the study of defect physics to the non-Hermitian regime. Copyright © 2024, The Authors. All rights reserved.

关键词： Defects

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Asymmetric Heat Transfer with Linear Conductive Metamaterials

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Physical Review Applied 2023年第3期20卷 034013-034013页

作者： Yishu Su Ying Li Minghong Qi Sebastien Guenneau Huagen Li Jian Xiong Center for Composite Materials and Structures Harbin Institute of Technology Harbin 150001 China Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou 310027 China International Joint Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang The Electromagnetics Academy of Zhejiang University Zhejiang University Haining 314400 China UMI 2004 Abraham de Moivre-CNRS Imperial College London London SW7 2AZ United Kingdom Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore

Asymmetric heat-transfer systems, often referred to as thermal diodes or thermal rectifiers, have garnered increasing interest due to their wide range of application possibilities. Most of those previous macroscopic asymmetric thermal devices either resort to nonlinear thermal conductivities with strong temperature dependence that may be quite limited by or fixed in natural materials or rely on active modulation that necessitates auxiliary energy payloads. Here, we establish a straightforward strategy of passively realizing asymmetric heat transfer with linear conductive materials. The strategy also introduces an interrogative perspective into the previous design of passive asymmetric heat transfer utilizing nonlinear thermal conductivity, correcting the misconception that thermal rectification is impossible with separable nonlinear thermal conductivity. The nonlinear-perturbation mode can be versatilely engineered to produce an effective and wide-ranging perturbation in heat conduction, which imitates and bypasses intrinsic thermal nonlinearity constraints set by naturally occurring counterparts. Independent experimental characterizations of surface thermal radiation and thermal convection verify that heat exchange between a graded linear thermal metamaterial and the ambient surroundings can be tailored to achieve macroscopic asymmetric heat transfer. Our work is envisaged to inspire conceptual models for heat-transfer control, serving as a robust and convenient platform for advanced thermal management and thermal computation.

关键词： Heat radiation Heat transfer Metamaterials Thermal conductivity

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Performing optical logic operations by a diffractive neural network

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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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Multiple Brillouin Zone Winding of Topological Chiral Edge States for Slow Light applications

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Physical Review Letters 2024年第15期132卷 156602-156602页

作者： Fujia Chen Haoran Xue Yuang Pan Maoren Wang Yuanhang Hu Li Zhang Qiaolu Chen Song Han Gui-geng Liu Zhen Gao Peiheng Zhou Wenyan Yin Hongsheng Chen Baile Zhang Yihao Yang State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou 310027 China International Joint Innovation Center The Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua 321099 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing 312000 China Department of Physics The Chinese University of Hong Kong Shatin Hong Kong SAR China Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education University of Electronic Science and Technology of China Chengdu 611731 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore 637371 Singapore Centre for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen 518055 China

Photonic Chern insulators are known for their topological chiral edge states (CESs), whose absolute existence is determined by the bulk band topology, but concrete dispersion can be engineered to exhibit various properties. For example, the previous theory suggested that the edge dispersion can wind many times around the Brillouin zone to slow down light, which can potentially overcome fundamental limitations in conventional slow-light devices: narrow bandwidth and keen sensitivity to fabrication imperfection. Here, we report the first experimental demonstration of this idea, achieved by coupling CESs with resonance-induced nearly flat bands. We show that the backscattering-immune hybridized CESs are significantly slowed down over a relatively broad bandwidth. Our work thus paves an avenue to broadband topological slow-light devices.

关键词： Light propagation, transmission & absorption Metamaterials Photonic crystals Polaritons Topological materials

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Large-area quantum-spin-Hall waveguide states in a three-layer topological photonic crystal heterostructure

arXiv

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arXiv 2022年

作者： Lan, Zhihao Chen, Menglin L.N. You, Jian Wei Sha, Wei E.I. Department of Electronic and Electrical Engineering University College London Torrington Place LondonWC1E 7JE United Kingdom Department of Electronic and Information Engineering The Hong Kong Polytechnic University Kowloon Hong Kong State Key Laboratory of Milimeter Waves Institute of Electromagnetic Space Southeast University Nanjing China Key Laboratory of Micro-nano Electronic Devices and Smart Systems of Zhejiang Province College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China

Topological photonic edge states are conventionally formed at the interface between two domains of topologically trivial and nontrivial photonic crystals. Recent works exploiting photonic quantum Hall and quantum valley Hall effects have shown that large-area topological waveguide states could be created in a three-layer topological heterostructure that consists of a finite-width domain featuring Dirac cone sandwiched between two domains of photonic crystals with opposite topological properties. In this work, we show that a new kind of large-area topological waveguide states could be created employing the photonic analogs of quantum spin Hall effect. Taking the well-used Wu-Hu model in topological photonics as an example, we show that sandwiching a finite-width domain of photonic crystals featuring double Dirac cone between two domains of expanded and shrunken unit cells could lead to the emergence of large-area topological helical waveguide states distributed uniformly in the middle domain. Importantly, we unveil a power-law scaling regarding to the size of the bandgap within which the large-area helical states reside as a function of the width of the middle domain, which implies that these large-area modes in principle could exist in the middle domain with arbitrary width. Moreover, pseudospin-momentum locking unidirectional propagations and robustness of these large-area waveguide modes against sharp bends are explicitly demonstrated. Our work enlarges the photonic systems and platforms that could be utilized for large-area-mode enabled topologically waveguiding. Copyright © 2022, The Authors. All rights reserved.

关键词： Quantum theory

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Reconfigurable Three-Dimensional Thermal Dome

arXiv

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arXiv 2023年

作者： Zhou, Yuhong Yang, Fubao Xu, Liujun Zhuang, Pengfei Wang, Dong Ouyang, Xiaoping Li, Ying Huang, Jiping Fudan University Shanghai200438 China Graduate School of China Academy of Engineering Physics Beijing100193 China School of Materials Science and Engineering Xiangtan University Xiangtan411105 China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou310027 China International Joint Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang The Electromagnetics Academy of Zhejiang University Zhejiang University Haining314400 China

Thermal metamaterial represents a groundbreaking approach to control heat conduction, and, as a crucial component, thermal invisibility is of utmost importance for heat management. Despite the flourishing development of thermal invisibility schemes, they still face two limitations in practical ap plications. First, objects are typically completely enclosed in traditional cloaks, making them difficult to use and unsuitable for objects with heat sources. Second, although some theoretical proposals have been put forth to change the thermal conductivity of materials to achieve dynamic invisibility, their designs are complex and rigid, making them unsuitable for large-scale use in real three-dimensional spaces Here, we propose a concept of a thermal dome to achieve three-dimensional invisibility. Our scheme includes an open functional area, greatly enhancing its usability and applicability. It features a reconfigurable structure, constructed with simple isotropic natural materials, making it suitable for dynamic requirements. The performance of our reconfigurable thermal dome has been confirmed through simulations and experiments, consistent with the theory. The introduction of this concept can greatly advance the development of thermal invisibility technology from theory to engineering and provide inspiration fo other physical domains, such as direct current electric fields and magnetic fields. Copyright © 2023, The Authors. All rights reserved.

关键词： Metamaterials

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Boundary-induced topological chiral extended states in Weyl metamaterial waveguides

arXiv

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arXiv 2024年

作者： Han, Ning Chen, Fujia Li, Mingzhu Zhao, Rui Li, Wenhao Chen, Qiaolu Zhang, Li Pan, Yuang Ma, Jingwen Yu, Zhi-Ming Chen, Hongsheng Yang, Yihao Interdisciplinary Center for Quantum Information 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 Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing312000 China School of Information and Electrical Engineering Hangzhou City University Hangzhou310015 China Department of Electronic Engineering The Chinese University of Hong Kong Shatin New Territories Hong Kong School of Physics Beijing Institute of Technology Beijing100081 China Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing100081 China

In topological physics, it is commonly understood that the existence of the boundary states of a topological system is inherently dictated by its bulk. A classic example is that the surface Fermi-arc states of a Weyl system are determined by the chiral charges of Weyl points within the bulk. Contrasting with this established perspective, here, we theoretically and experimentally discover a family of topological chiral bulk states extending over photonic Weyl metamaterial waveguides, solely induced by the waveguide boundaries, independently of the waveguide width. Notably, these bulk states showcase discrete momenta and function as "wormhole" tunnels that connect Fermi-arc surface states living in different two-dimensional (2D) spaces via a third dimension. Our work offers a magnetic-field-free mechanism for robust chiral bulk transport of waves and highlights the boundaries as a new degree of freedom to regulate bulk Weyl quasiparticles. Copyright © 2024, The Authors. All rights reserved.

关键词： Metamaterials

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