Origin and Customization of Bandgap in Chiral Phononic Crystals

TL;DR

This paper clarifies the physical mechanisms behind bandgap formation in chiral phononic crystals, introduces a new approach for bandgap customization, and validates it through simulations and experiments.

Contribution

It unveils the physical reasons for bandgap controversy and proposes a novel spherical hinge method for tuning bandgap properties.

Findings

Identified obstacles in coupled acoustic and optic branches affecting bandgap.

Proposed spherical hinge approach to customize bandgap frequency and width.

Validated the approach with numerical simulations and experimental results.

Abstract

The wave equation governing the wave propagation in chiral phononic crystals, established through force equilibrium law, conceals the underlying physical information. This has led to a controversy over the bandgap mechanism. In this letter, we theoretically unveil the reason of this controversy, and put forward an alternative approach from wave behavior to formulate the wave equation, offering a new pathway to articulate the bandgap physics directly. We identify the obstacles in coupled acoustic and optic branches to widen and lower the bandgap, and introduce an approach based on spherical hinges to decrease the barriers, for customizing the bandgap frequency and width. Finally, we validate our proposal through numerical simulation and experimental demonstration.