Frequency selective topological edge wave routing in meta-structures made of cylinders

The propagation direction of edge states is essentially related to the band topology invariant of the constituent structures and the momentum of the excitation source. However, it is difficult to control the propagation path when the chirality of the excitation source and the boundary structures are determined. Here, we study a frequency selective waveguide structure based on photonic crystals with different topological invariant characterized by bulk polarization. By designing different types of interface made from spatially arranged dielectric rods, distinct topological edge states could be realized at different frequencies in the band gap. Therefore, we can construct a meta-structure in which the wave guiding path can be switched by the excitation frequency. Our study provides an alternative approach to designing topological devices such as frequency dependent optical waveguides and frequency division devices. (C) 2020 Optical Society of America