Dual-band large-area topological edge states and higher-order corner states in a valley Hall photonic crystal
Lianlian Du, Yahong Liu, Meize Li, Xin Zhou, Song Wang, Qian Zhao, Zhenfei Li, Liyun Tao, Xiang Xiao, Kun Song, Xiaopeng Zhao
Abstract
Topological photonics has been an emerging research field in optics and a promising area within the broader realm of topological physics. One recent focus has been on the exploration of large-area topological edge states with tunable widths. At the same time, there has been considerable interest in higher-order topological corner states that can manipulate wave localization. Challenges remain in achieving multiband large-area topological edge states and higher-order corner states to flexibly manipulate the localization and transmission of electromagnetic waves. In this paper, we propose a valley Hall photonic crystal (VPC) with two types of interfaces capable of achieving both large-area topological edge states and large-area higher-order corner states in the dual-band frequency ranges. We demonstrate numerically and experimentally that large-area edge states enable width-tunable waveguide transmission and topological cavities in two frequency ranges. In addition, we also construct corner structures based on the two interfaces and achieve large-area higher-order corner states at dual-band frequency ranges. Therefore, our proposed VPC possesses both large-area topological edge states and large-area corner states at dual-band frequency ranges. It is expected that this VPC can serve as a multifunctional device for manipulating electromagnetic waves.