Topological waveguide states with adjustable width in elastic heterostructures with periodic semi-circular holes

Abstract

The topological interface state in the one-dimensional periodic structure is difficult to be flexibly applied to practical engineering. Here we construct a ubiquitous sandwich structure with periodic semi-circular holes to realize the topological waveguide states. Firstly, we use finite element method and eigenmode matching theory to calculate the band structure of SH guided wave in one-dimensional phononic crystal plate. Dirac points are constructed through zone folding, and band inversion can be obtained through contracting and expanding the semi-circular holes on this basis. Then construct the sandwich structure by adjusting the period of the middle phononic crystal plate to obtain topological waveguide states of different widths. This structure can not only obtain the topology state with adjustable width, but also obtain the defect state, which can be used for filtering and guiding waves.