Topological interface modes in local resonant acoustic systems

Abstract

Topological phononic crystals (PCs) are periodic artificial structures which can support nontrivial acoustic topological bands, and their topological properties are linked to the existence of topological edge modes. Most previous studies focused on the topological edge modes in Bragg gaps which are induced by lattice scatterings. While local resonant gaps would be of great use in subwavelength control of acoustic waves, whether it is possible to achieve topological interface states in local resonant gaps is a question. In this article, we study the topological bands near local resonant gaps in a time-reversal symmetric acoustic systems and elaborate the evolution of band structure using a spring-mass model. Our acoustic structure can produce three band gaps in subwavelength region: one originates from local resonance of unit cell and the other two stem from band folding. It is found that the topological interface states can only exist in the band folding induced band gaps but never appear in the local resonant band gap. The numerical simulation perfectly agrees with theoretical results. Our study provides an approach of localizing the subwavelength acoustic wave.

References in corpus (7)

• Topological Photonics
• Topological Acoustics
• Observation of phononic helical edge states in a mechanical 'topological insulator'
• Observation of topological valley transport of sound in sonic crystals
• Selective enhancement of topologically induced interface states in a dielectric resonator chain
• Observation of the topological soliton state in the Su-Schrieffer-Heeger model
• Topological modes bound to dislocations in mechanical metamaterials

Cited by in corpus (8)

• Topologically protected edge modes in one-dimensional chains of subwavelength resonators
• Topological Protection in a Strongly Nonlinear Interface Lattice
• Topological interface states induced by incident angle in the 1D elastic wave system
• Topological Surface-plasmon-polaritons on Corrugated Metal-dielectric Surfaces
• Tunability of Spin-Dependent Secondary Topological Interface States Induced in an Optical Complex Superlattice
• The topological dynamics of continuum lattice grid structures
• Confining and channeling sound through coupled resonators
• Emergent Non-Hermitian Edge Polarisation in an Hermitian Tight-binding Model