Experimental observation of high-order topological corner states in 2D photonic Kagome lattice

In this paper we experimentally realize high-order photonic topological insulator as a two-dimensional triangular distorted Kagome lattice that supports two types of topological states: 1D topological edge states and 0D high-order topological states localized at the corners. Using near-field scanning technique we demonstrate both topological edge states and topological corner state in microwave frequency spectrum. The experimental results are in perfect agreement with numerical simulations of finite structure.