Topological multipolar corner state in a supercell metasurface and its interplay with two-dimensional materials  

作　　者：Zhaojian Zhang Junbo Yang Te Du Xinpeng Jiang 

机构地区：[1]College of Liberal Arts and Sciences,National University of Defense Technology,Changsha 410073,China [2]Center of Material Science,National University of Defense Technology,Changsha 410073,China

出　　处：《Photonics Research》2022年第4期855-869,共15页光子学研究（英文版）

基　　金：National Natural Science Foundation of China(60907003,61805278,62005107);China Postdoctoral Science Foundation(2018M633704);National University of Defense Technology(JC13-02-13,ZK17-03-01);Natural Science Foundation of Hunan Province(13JJ3001);Program for New Century Excellent Talents in University(NCET-12-0142);Hunan Provincial Innovation Foundation for Postgraduate(CX20200039);Natural Science Research of Jiangsu Higher Education Institutions of China(20KJB140007).

摘　　要：Second-order topological insulators(SOTIs) have recently attracted much attention due to their capability to support lower-dimensional topological states, namely, the corner states. Here, we demonstrate that properly designed supercell metasurfaces can support photonic corner states, meanwhile further serving as an ideal platform for the implementations of topological polaritons and dynamically reconfigurable corner states by assembling two-dimensional materials. Such metasurfaces consist of an array of finite-sized SOTIs mimicking the twodimensional Su–Schrieffer–Heeger model. We reveal that the topological transition happens in unit cells without the bandgap, and nondegenerate multipolar corner states emerge in the supercell metasurface due to the inter-and intrasupercell coupling effects. Especially since these corner states are above the light line of the metasurface, we realize the collective stimulation of the two dipolar corner states and their superposition state via far-field excitation. By stacking monolayer hexagonal boron nitride film onto the metasurface, we further achieve the topological phonon polaritons through the strong coupling between the corner state and the phonon, which is confirmed by the Rabi splitting as well as anticrossing behavior emerging in the transmission spectra.Furthermore, we reveal the robustness of the corner state and strong coupling by introducing defects into the metasurface. Finally, tunable corner state and strong coupling with on-demand control are realized by assembling monolayer graphene onto the metasurface. Our theoretical study proposes a unique hybrid-material platform for topological polaritonics and reconfigurable topological photonics, which can promote large-area topological applications in practice.

关 键 词：POLAR WHILE CORNER 

分 类 号：O469[理学—凝聚态物理]