The breaking of Lorentz reciprocity law is a non-trivial task, since it usually requires bulky magnets or complicated time-modulation dynamic techniques to be accomplished. In this work, we present a simple and compact design of a nonlinear bifacial dielectric metasurface to achieve strong self-induced passive nonreciprocal transmission without the use of external biases. The proposed design is ideal for free space optics applications, can operate under both incident polarizations, and require very low input excitation power to reach the nonreciprocal regime. It is composed of two passive silicon-based metasurfaces exhibiting Fano and Lorentzian resonances embedded in an ultrathin glass substrate. Highly asymmetric field enhancement is achieved with the proposed design that leads to strong nonreciprocity at low excitation intensities due to the large Kerr nonlinearity of silicon. Moreover, cascade designs are presented to further improve the insertion loss, broaden the nonreciprocal intensity range, and increase the isolation ratio by enhancing the transmission contrast. Finally, it is demonstrated that the proposed nonlinear metasurface is robust to fabrication imperfections and can achieve large isolation for a relative broad input power range even in the case of two incident waves impinging at the same time from both directions. The current work is expected to lead to new compact nonreciprocal nanophotonic devices, such as all-optical diodes, isolators, circulators, and ultrathin protective layers for sensitive optical components.
Dual-polarization control of broadband nonreciprocal thermal radiation by combining local and nonlocal metasurfaces
The University of Hong Kong（香港大学）；State Key Laboratory of Optical Quantum Materials, The University of Hong Kong（香港大学光学量子材料国家重点实验室）；Institute of Engineering Thermophysics, MOE Key Laboratory for Power Machinery and Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University（上海交通大学机械工程学院动力机械工程教育部重点实验室工程热物理研究所）；Department of Electrical and Computer Engineering, National University of Singapore（新加坡国立大学电气与计算机工程系）；Key Laboratory of Terahertz Solid State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences（中国科学院上海微系统与信息技术研究所太赫兹固态技术重点实验室）；National Engineering Research Center of Electromagnetic Radiation Control Materials, University of Electronic Science and Technology of China（电子科技大学电磁辐射控制材料国家工程研究中心）
Bound states in the continuum in multilayered time-varying metasurfaces
Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院理论固体物理研究所）；Institute for Analysis, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院分析学研究所）；Institute of Nanotechnology, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院纳米技术研究所）；Center for Integrated Quantum Science and Technology (IQST), Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院综合量子科学与技术中心）
Maximum non reciprocity in metasurfaces of gyrotropic rods
Institute of Electronic Structure and Laser, Foundation of Research and Technology Hellas（电子结构与激光研究所，希腊研究基金会）；School of Electrical and Computer Engineering, National Technical University of Athens（雅典国立技术大学电气与计算机工程学院）；Department of Physics, National and Kapodistrian University of Athens（雅典诺米卡卡波迪斯特里亚斯大学物理系）
Imaginary Gauge Fields for One-Way Transparency and Absorption in a Passive Metasurface
New Cornerstone Science Laboratory, Department of Physics, University of Hong Kong（香港大学新cornerstone科学实验室）；School of Physics and Optoelectronics, South China University of Technology（华南理工大学物理与光电学院）；School of Engineering, University of Birmingham（伯明翰大学工程学院）；State Key Laboratory of Optical Quantum Materials, University of Hong Kong（香港大学光学量子材料国家重点实验室）；Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area（粤港澳大湾区量子科学中心）；Materials Innovation Institute for Life Sciences and Energy (MILES), HKU-SIRI, Shenzhen（深圳港大-深港研究院生命科学与能源材料创新研究所）；Department of Electrical & Electronic Engineering, University of Hong Kong（香港大学电子电气工程系）
