Experimental realization of topological photonic quasicrystals with the eightfold rotational symmetry

Abstract

The topological states in aperiodic systems have attracted extensive attention, which exhibit unique characteristics beyond the periodic structures. Photonic quasicrystals, exhibiting unlimited rotational symmetry, possess a remarkably rich and complex physics. Here, we construct an Ammann–Beenker tiling topological photonic quasicrystal with eightfold rotational symmetry by utilizing pure dielectric materials. The implemented experiments demonstrate the presence of a photonic bandgap and rotationally symmetric bulk state distribution and directly observe the corner and edge states within the photonic quasicrystal. Unlike conventional photonic crystals, these corner and edge states asymmetrically distribute along specific segments of the edges and strongly rely on the boundary geometry of the photonic quasicrystals. Our studies enrich the topological physics in the quasicrystal systems and provide a platform for exploring topological phases beyond the present topological classification of crystal structures.