Temperature-controlled tunable underwater acoustic topological insulators

Abstract

Topological insulators provide a new route to design acoustic metamaterials, which can exhibit novel propagation properties. However, most of the current topological acoustic metamaterials are characterized by a passive response and operated at fixed frequency ranges, and there are few reports on the effect of temperature of water on acoustic topological insulators. Therefore, in this paper, we design the temperature-controlled tunable underwater acoustic topological insulators. The topological acoustic system is composed of a triangular array of triangular steel columns embedded in water. We calculate the Dirac point frequencies and bulk band structures at different temperatures. The results show that the topological nontrivial bandgap frequency range is very sensitive to the temperature of water. We also use some numerical examples to demonstrate the robustness and defect-immune properties of the topological phononic crystals, and the topological properties can be switched by controlling the temperature of water. Our study shows that the change in the temperature can behave as an acoustic switch, which may have applications in the underwater sound waveguide as well as underwater communications.