Topological photonic states have promising applications in slow light, photon sorting, and optical buffering. However, realizing such states in non-Hermitian systems has been challenging due to their complexity and elusive properties. In this work, we have experimentally realized a topological rainbow in non-Hermitian photonic crystals by controlling loss in the microwave frequency range for what we believe is the first time. We reveal that the lossy photonic crystal provides a reliable platform for the study of non-Hermitian photonics, and loss is also taken as a degree of freedom to modulate topological states, both theoretically and experimentally. This work opens a way for the construction of a non-Hermitian photonic crystal platform, will greatly promote the development of topological photonic devices, and will lay a foundation for the real-world applications.

随着超快光学的发展和对以Bi₂Te₃为代表的拓扑绝缘体材料研究的深入，近几年，将拓扑绝缘体薄膜应用于超快光器件的研究方向发展迅速并发表了一系列研究成果，本文综述了近年来基于拓扑绝缘体材料的超快激光及光器件的研究。从材料结构及制备方法出发，介绍了其独特的光学及光电特性，总结了其在超快激光及光器件中的应用研究进展，回顾和讨论了这一领域的成就和挑战，并对将拓扑绝缘体薄膜材料应用于超快光器件的进一步研究进行了展望。

奇异点是非厄米系统中的特殊点，奇异点附近的参数空间会出现很多新奇的物理现象。超表面是物理学近年来兴起的一个研究热点，人们基于超表面的平台已经设计实现了大量性能优越的器件。超表面的出现为研究奇异点提供了一个易操作的平台，通过精确控制超表面的结构参数，可以方便地研究奇异点周围的参数空间。研究超表面中的奇异点也为研究新的物理规律提供了基础的平台，文中首先介绍了奇异点和超表面中的奇异点的基本理论，之后介绍了超表面中奇异点的最新研究进展，最后对目前该领域亟待解决的问题进行了分析总结，对该领域的发展进行了展望。