19th Asia-Pacific Vibration Conference (APVC2021)

Acoustic valley transport has become a research hotspot in the field of acoustic wave regulation, due to its backscatter suppression and strong robustness to defects and disorder. The local resonance band gap or the Bragg scattering band gap can form Dirac cones under the condition of point group symmetry, which is the prerequisite for realizing the acoustic topological valley state. Based on the coupling effect of local resonance and Bragg scattering, a rotatable scatterer containing Helmholtz resonant cavities is designed in this paper and arranged in a triangular lattice. The valley Hall phase transition is realized through the mechanism of rotating scatterer, and it is found that the topological edge state energy bands do not coincide at the interface composed of different valley Hall phase crystals, which is different from the local resonance type or the Bragg scattering type. This feature makes the valley transmission of interface states at the curved zigzag interface composed of different valley Hall phase crystals is affected. We analyze the types of interfaces that compose a curved channel, and give a method to distinguish the interface types. On this basis, the valley state transmission of the separated edge states in the curved channel is realized. This research provides new ideas for multi-band acoustic wave control.

Acoustic valley transport; Coupling effect; Valley Hall phase; Separated interface states