Reconfigurable Wannier-type higher-order photonic topological insulators

Abstract

Abstract Recently, reconfigurable photonic topological insulators (PTIs) have been studied in the low-order PTIs and quadrupole higher-order PTIs. Different from previous works, in this paper, we report reconfigurable Wannier-type higher-order PTIs based on the kagome-lattice BaTiO3 photonic crystal (PC). Considering both intra-cell and inter-cell coupling, the traditional topological edge and corner states as well as a new type of corner state are found at the interface between the non-trivial and trivial BaTiO3 PCs. Active switching between different topological edge and corner states at the same frequency can be realized by freely tuning the refractive index of BaTiO3.