Topologically protected elastic waves in one-dimensional phononic crystals of continuous media

TL;DR

This paper demonstrates the design and observation of topologically protected elastic waves in one-dimensional silica-based phononic crystals, revealing interface states that could enable advanced phononic devices.

Contribution

It introduces a method to create topologically distinct phononic bandgaps in 1D silica-based PnCs and observes protected elastic wave states at their interfaces.

Findings

Observation of a topological interface mode with high quality factor (~5,650)

Confirmation of spatial confinement via photoelastic imaging

Potential for novel phononic device applications

Abstract

We report the design of silica-based 1D phononic crystals (PnCs) with topologically distinct complete phononic bandgaps (PnBGs) and the observation of a topologically protected state of elastic waves at their interface. By choosing different structural parameters of unit cells, two PnCs can possess a common PnBG with different topological nature. At the interface between the two PnCs, a topological interface mode with a quality factor of ~5,650 is observed in the PnBG. Spatial confinement of the interface mode is also confirmed by using photoelastic imaging technique. Such topologically protected elastic states are potentially applicable for constructing novel phononic devices.