Multi-band Acoustic Topological Insulator Based on Valley Hall Effect

In this paper, a multi-band acoustic topological insulator based on the Valley Hall effect is designed. Based on the mirror symmetry in the C-3v point group phononic crystal, by changing the parameters of the primitive cell, the phononic crystal simultaneously has multiple linear Dirac degenerate points at the K point of the Brillouin zone, which can realize multi-band topology valley transmission. The whole triangular multi-band acoustic topological valley insulator system has C-3v symmetry. By rotating the clover-like scatterer, the mirror symmetry of the structure can be broken, thereby opening the degeneracy at the Dirac point. The energy band is reversed at the K point, realizing the Valley Hall phase transition. By connecting different structural systems, boundary states are constructed to simulate topologically protected edge acoustic transmission. Different phonon crystal structures are further constructed, and their acoustic transmission characteristics are verified by finite element algorithms. This paper can provide guidance for the design and engineering application of multi-band acoustic antennas, acoustic logic control gate circuits, and other functional devices for acoustic communication.