Topological Transmission in Suzuki-phase sonic crystals

Abstract

[EN] This work reports novel topological sound transmission effects in sonic crystals denominated Suzuki phase without spatial inversion symmetry, consisting of a rectangular lattice of vacancies created in a triangular lattice. The Suzuki phase contains three types of topological states on the four possible interfaces obtained from two different topological phases. A generalized folding method explains the band structure and the Dirac point in the Suzuki phase, which is related to the underlying triangular lattice. The interface between two Dirac cone-opened systems has quantized valley-Chern number differences, supporting the presence of topological edge states. The eigenmodes topologically protected at the different interfaces have defined symmetries, which affect the topological sound transmission, such as the phenomenon of topological deaf bands. The propagation of topological eigenmodes on the same interface is also different, which can be quantified by Shannon entropy, making the topological transport dependent on the frequency of the edge states. Based on the abundant topological edge states of Suzuki phase, we design a multifunctional device with acoustic diodes, multi-channel transmission, and selective acoustic transmission. Numerical calculations and experimental results demonstrate the topological transmission. Our work extends the research platform of acoustic topological states to lattices without spatial inversion symmetry, which opens new avenues for enriching topological states with broad engineering applications.