Tunable Nonlinear Topological Insulator for Acoustic Waves

Abstract

Inspired by the quantum spin Hall effect, the authors propose a tunable nonlinear topological insulator for acoustic waves, which could be an ideal framework for lossless information transport. The band structure of the hexagonal unit cell is obtained analytically, using Bloch's theorem and zone-folding techniques, revealing doubly degenerate Dirac cones. Breaking of inversion symmetry creates energy-dependent band gaps with topologically protected edge states that are robust against backscattering at arbitrary interfaces. The proposed topological insulator could be a stepping-stone platform toward building tunable acoustic devices, interconnects, and electroacoustic integrated circuits.