Zhang Li, Yang Yihao, Lin Zhi-Kang, Qin Pengfei, Chen Qiaolu, Gao Fei, Li Erping, Jiang Jian-Hua, Zhang Baile, Chen Hongsheng
Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China.
ZJU-Hangzhou Global Science and Technology Innovation Center Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang The Electromagnetics Academy at Zhejiang University Zhejiang University Hangzhou 310027 China.
Adv Sci (Weinh). 2020 Jan 27;7(6):1902724. doi: 10.1002/advs.201902724. eCollection 2020 Mar.
Photonic topological states have revolutionized the understanding of the propagation and scattering of light. The recent discovery of higher-order photonic topological insulators opens an emergent horizon for 0D topological corner states. However, the previous realizations of higher-order topological insulators in electromagnetic-wave systems suffer from either a limited operational frequency range due to the lumped components involved or a bulky structure with a large footprint, which are unfavorable for achieving compact photonic devices. To overcome these limitations, a planar surface-wave photonic crystal realization of 2D higher-order topological insulators is hereby demonstrated experimentally. The surface-wave photonic crystals exhibit a very large bulk bandgap (a bandwidth of 28%) due to multiple Bragg scatterings and host 1D gapped edge states described by massive Dirac equations. The topology of those higher-dimensional photonic bands leads to the emergence of in-gap 0D corner states, which provide a route toward robust cavity modes for scalable compact photonic devices.
光子拓扑态彻底改变了人们对光的传播和散射的理解。高阶光子拓扑绝缘体的最新发现为零维拓扑角态开辟了一个新的领域。然而，此前在电磁波系统中实现高阶拓扑绝缘体时，要么由于涉及集总元件而导致工作频率范围有限，要么结构庞大、占用面积大，这对于实现紧凑型光子器件而言是不利的。为克服这些限制，本文通过实验展示了二维高阶拓扑绝缘体的平面表面波光光子晶体实现方案。由于多次布拉格散射，表面波光光子晶体展现出非常大的体带隙（带宽为28%），并拥有由大质量狄拉克方程描述的一维带隙边缘态。那些高维光子能带的拓扑结构导致了带隙内零维角态的出现，这为可扩展紧凑型光子器件的稳健腔模提供了一条途径。
