Interface State in One-dimensional Acoustic Resonator System with Inversion Symmetry Breaking

Abstract

Topological sonic crystals are artificial periodic structures that support robust edge or interface state. Most previous studies on interface state in one-dimensional system heavily rely on Su-Schrieffer-Heeger (SSH) model, which modulates inter and intra hopping strength to yield a nontrivial topological phase. Whether it is possible to achieve interface states by connecting two trivial phases remains a question. To this point, in this paper, we propose a novel method of breaking the inversion symmetry of diatomic and elaborate the underlying mechanism using a spring-mass model. Instead of modulating spring stiffness corresponding to hopping strength which is intrinsically requested in the SSH model, we perturb the masses to break inversion symmetry while springs remain unchanged. Although breaking inversion symmetry in diatomic does not lead to a nontrivial phase, it is found that the interface state would still emerge within the chain formed by connecting two different configurations. Subsequently, this mechanism is applied to a one-dimensional acoustic resonator system connecting two different configurations to realize interface state. Simulation results reveal that acoustic wave has strongly localized at predicted interface frequency. Our study provides a novel approach of producing interface states in the one-dimensional acoustic system.