Fig. 2: The projected band structures (PBS) of TIs with directional bandgaps.
From: Bulk-local-density-of-state correspondence in topological insulators
a Schematic of a finite-size photonic TI with boundary rods having a smaller radius than the bulk rods. The zoom-in inset presents the position of the probe to measure the projective band structure. The radius of the bulk and edge rods are 0.11a and 0.1a respectively. b The PBS of the unperturbed lattice. The white (blue) lines are the numerically simulated bulk and edge states. The bright and dark colors represent the experimentally measured PBS. The zoom-in inset shows the 1D edge state is an in-gap state. c The PBS of the perturbed lattice. The elements have the same meaning as in (b). The zoom-in inset shows the 1D edge state is embedded into the bulk spectrum for the second band gap.
