Fig. 3: Observation of the second-order photonic topological hinge states.
From: Realization of a three-dimensional photonic higher-order topological insulator
a Simulated bulk (grey lines), surface (orange lines), and hinge (blue lines) state dispersions along the kz direction. The cyan curve represents the light cone. b Simulated electric field distribution of the hinge states corresponding to the black triangle in a. c Measured transmission spectra of the hinge (blue color) and surface (orange color) states. Measured (d) and simulated (e) electric field distributions of the topological hinge states at 14.9 GHz with the source antenna (cyan star) placed at the middle of the hinge. f Measured (color map) and simulated (white dashed line) hinge state dispersions along the kz direction.
