Fig. 1
Light-trapping on a dislocation due to dual-topology. a Schematic of a dislocation and the Burgers vector in a rectangular lattice. A photonic-bound state (red region) is localized at the center of the dislocation. b Illustration of the cut-and-glue technique. Inserting a chunk of photonic crystal with trivial topology (the green strip) into a topological PhC with a dislocation yields two edge channels at opposite boundaries. Because of the additional lattice period in the lower edge, on the left (right) side of the dislocation there is a π (no) phase difference between the two edge states. c The π phase shift in the edge channels yields a sign-change in the Dirac mass across the dislocation, forming a Dirac mass ___domain-wall which results in a photonic Jackiw–Rebbi soliton mode
