全介质光子晶体的简并点及其对电磁波调控的理论与实验研究

Topological electromagnetic (or photonic) state (TES), a hot topic, has been attracting much attention in material science, microwave and optoelectronic engineering. As the core design technology of future photoelectric devices with high efficiency, the development of TESs with symmetry protection has a direct impact to future optical integrated circuits and optical communications. In this project, we focus on the degenerated point existing in all-dielectric photonic crystal from the perspective of full band application. We study the characteristics of such degenerated point and its manipulation on electromagnetic wave in the purpose of designing new topological devices. By studying the accidental degenerated point and its relationship with lattice structure and components’ characteristics in 2D system, a new application with such degenerated point will be proposed, such as superradiance and cloaking. As an important part of our project, we give an intensive study to the degenerated point in 3D photonic crystal which is just emerging area. Focusing on the system’s symmetry effect on the performance of degenerated point, we are supposed to find more conserved quantities and new topological variables to eventually build more varieties of TESs. By combining both theoretical study and experimental verification, the project will be reliable and provide a theoretical basis for new topological electromagnetic devices.

电磁（光）拓扑态是目前材料科学、微波和光电工程应用中的一个重要课题。作为设计未来高效率新型光电器件的核心技术，具有拓扑对称保护性的电磁拓扑态的发展研究直接影响到未来光集成电路和光通信的开发。本项目从未来全频段应用的角度出发，以全介质光子晶体为研究对象，以构建新型电磁拓扑态器件为目的，研究光子晶体体系中简并点形成的物理过程及其对电磁波的调控。通过对二维光子体系偶然简并点的形成与光子晶体的点阵结构和结构参数的关系研究，揭示偶然简并点建立的物理过程，提出相关应用，理论和实验实现诸如超散射、隐身等电磁现象。重点对刚起步的三维体系简并点的问题开展深入研究，通过对系统对称性对其调控作用的研究，寻找新领域中的守恒量，发现新的拓扑量，构造更为丰富的拓扑保护态。本项目采用理论和实验验证相结合的研究方法，通过开展相关实验研究，验证理论结果，为电磁拓扑器件的设计与制备提供理论基础。

项目以实现有效控制、捕获电磁波，实现能量高强局域和高强传输为目标，围绕全介质光子晶体简并点的电磁性质及其对电磁波调控的理论基础和关键技术展开。项目以微波段光子晶体为研究对象，开展了基于材料对称性和结构非点群操作对能带简并点的研究，提出了简并点与拓扑相之间的关系，探讨了种类更为丰富的体拓扑相的电磁表现。项目创新性地提出了一种区别于高阶拓扑绝缘体的低维电磁态实现机制，这种Jackiw-Rebbi局域模具有稳健抗缺陷的性质，；通过理论计算、原型设计、实验表征相结合的研究方式，首次成功观测到拓扑材料中旋错结构导致的稳健光子局域态和分数电荷，为拓扑晶体绝缘体的进一步研究提供了实验基础；应用层面，较为深入地研究了对称性对简并点破缺的调控，提出了一种磁可调完美磁导体和可调谐多功能电磁调控器；构建了一种亚波长近零磁场下的电磁手性边缘态。本项目的研究对厄密、非厄密体系中的拓扑激光、准周期光子晶体等方面有着重要的启发意义，为后续拓扑原型器件提供了理论和实验基础。