Floquet拓扑光子绝缘体研究进展(特邀)

Research Progress of Floquet Topological Photonic Insulators(Invited)

拓扑光子学是光学领域一个重要的新兴研究方向,它的奇异光学响应特性颠覆了人们对光传播的理解,为人工操控光的传播提供了一种全新方法。Floquet拓扑光子绝缘体是拓扑光子学的一个重要分支,它利用周期性的驱动来探索物质的相变过程,发现了很多违反直觉的新奇物理现象。本文综述了近十年来Floquet拓扑光子绝缘体的主要研究进展。根据实现方式将其分为基于时间调制、基于空间调制、基于耦合谐振调制的三个大类进行详细论述。对于每一类Floquet拓扑光子绝缘体,从基础理论和物理实现平台两个方面论述了Floquet拓扑光子绝缘体的独特光学特性和奇异物理现象,并讨论了其潜在的应用前景。最后,总结了该领域当前面临的主要挑战,并对Floquet拓扑光子绝缘体的未来研究方向进行了展望。

Topological photonics is an important and rapidly growing field that offers a powerful way to manipulate light.The geometric and topological ideas in this field have thoroughly changed our understanding of light propagation.Floquet topological insulators are an important branch of topological photonics,where many novel physical phenomena are waiting to be explored.This is mainly due to the condensed matter community,which utilizes periodically driven systems to reveal new phases of matter that do not exist in equilibrium systems.This paper reviews the research on Floquet topological optical insulators over the last decade,starting from a classification of their implementations as time-based modulation,space-based modulation and resonator-coupling-based modulation of Floquet topological photonic insulators.More specifically,time-modulated Floquet topological photonic insulators represent a unique class of artificial photonic structures with special topological properties,characterized by the dynamic modulation of topological phase through a periodic time function.This modulation method introduces a distinct control mechanism to photonic systems,leading to an unprecedented light transport.A key feature of time-modulated Floquet topological photonic insulators is the realization of topological edge states by breaking time-reversal symmetry.These edge states can propagate unidirectionally along the system boundaries and exhibit robustness against defects and back-scattering.Compared with traditional static topological photonic insulators,the time-based modulation method introduces a new degree of freedom in the temporal domain,thereby offering a wider range of control strategies and application potential.Given the theoretical limitations of time-modulated Floquet topological photonic insulators along with experimental constraints due to the inability of active switching frequencies to meet experimental demands,practically experimental demonstrations in this field have encountered significant restrictions.To address this challenge,researchers have initiated the exploration of alternative methodologies.Among these,space-based Floquet topological photonic insulators have emerged as a noteworthy direction.This approach employs one spatial dimension as a surrogate for the time dimension,thereby enabling the realization of pertinent topological properties in Floquet topological photonic insulators without requiring additionally high switching frequencies.Therefore,this approach has garnered significant attention and achieved substantial progress in the field.However,due to the incompatibility with integrated photonic systems,the integration of temporal or spatial modulation on a semiconductor platform remains a challenge.To address this issue,the two-dimensional structure of coupled resonator optical waveguides has emerged as a robust platform for the study of topological photonic insulators,thanks to its unique structure and compatibility with traditional photonic integrated circuits.So far,research on Floquet topological photonic insulators based on coupled resonances is garnering increasing attention.In summary,we have demonstrated the unique topological properties and amazing physical phenomena as well as the broad research progress in applications are presented from both theoretical and applied aspects.The achievements and challenges in this field are reviewed and discussed,and further research on Floquet topological photonic insulators is foreseen.