拓扑光子晶体与超构光子学(特邀)

Topological Photonic Crystals and Metaphotonics(Invited)

拓扑光子学逐步成为重要的物理光学原理和方法,其光场调控的新颖方式引起了人们极大的兴趣。近年来人们借助拓扑光子学理论,采用光子晶体、超构表面等一类人工亚波长光学超结构,提出并实现了微波波段或光波段的宽带单向传输、抗散射传输等新奇光学现象。根据拓扑光子学的发展历程,简要回顾了基于类量子霍尔、类量子自旋霍尔、类量子能谷霍尔等类量子效应光子晶体的拓扑物理特性和设计方法。进一步,分析了拓扑光子晶体在微纳集成光子与光量子器件方面的潜在应用。未来,随着人们对超结构的物理原理、光电设计、制备工艺、封装测试等研究的不断深入,超构光子学将成为新一代信息技术领域的重要组成部分,并有望在硅光电子学、集成电路、微光学技术、显微成像、光量子计算、量子精密测量等基础与应用领域,产生积极深远的影响。

Topological physics originated from solid state physics and is used to explain the integer Hall conductivity of boundary states in quantum Hall effect.The boundary state realized by topological theory will naturally have some anti-scattering ability in physical principle.Then,by analogy with condensed matter topology,topological theory is applied to photonics,that is,topological photonics is also proposed,which has gradually become an important photonics principle and method.Its novel way of light field regulation has aroused great interest.As an important branch of metaphotonics,topological photonics theory is used in the design of various optical structures.The sub-wavelength artificial optical metamaterials,e.g.,photonic crystals and metasurfaces,are applied to propose and realize various novel optical phenomena,including broadband unidirectional propagation and robust transport in microwave or optical band.This paper focuses on topological photonic crystals.According to its development history,the topological physical properties and design methods of photonic crystals based on the optical analogous of topological features such as the effects of quantum Hall,quantum spin Hall and quantum valley Hall are reviewed.Three kinds of topological photonic crystals are introduced,which use symmetry breaking to split degenerate points and open non-trivial band gap.For example,quantum-Hall photonic crystals break time reversal symmetry by using external magnetic field of gyromagnetic crystals.By introducing the coupling of TE and TM modes into bianisotropic media or metal materials,one can realize quantum-spinHall photonic crystals with the degeneracy broken of TE and TM modes.Quantum-valley-Hall photonic crystals break the degeneracy of Dirac points by the inversion symmetry broken of the honeycomb lattice.The bulk-edge correspondence in topological theory is explained,and many practical works to realize the robust edge state of topological photonic crystals in theory or experiment are given.Furthermore,the potential applications of topological photonic crystals in micro-nano integrated photonic and quantum optics devices are analyzed,such as robust transport of optical signals,which can still achieve high transmittance under the condition of sharp bending or structural defects.Topological photonic crystals are used to realize various passive devices,such as optical routing,wavelength division multiplexer,optical beam splitter and optical microcavity.Some active devices,e.g.tunable waveguides,optical switches and laser resonators,are also realized by topological photonic crystals.Topological photonic crystals can be used to design quantum optics devices,including quantum light source and two-photon interference device.At the same time,as another important branch of metaphotonics,metasurfaces have also attracted extensive attention.This paper also briefly introduces the important achievements of metasurfaces in micro-optical imaging.In the future,with the further research on physics principles,optoelectronic design,preparation process,package testing and so on in metamaterials,metaphotonics will become an important part of the new generation of information technology and is expected to have a positive and far-reaching impact on the basic and application fields of silicon optoelectronics,integrated circuits,micro-optical technology,micrography,quantum computing,quantum precision measurement,etc.