Stopping and reversing sound via dynamic dispersion tuning in a phononic metamaterial

TL;DR

This paper introduces a phononic metamaterial that uses dynamic dispersion tuning via prestress to control sound propagation, enabling slowing, stopping, and reversing sound signals in a versatile, scalable system.

Contribution

It presents a novel method to dynamically tune phonon dispersion in a metamaterial through prestress, allowing control over sound propagation and signal reversal.

Findings

Dispersionless band achieved at the transition point.

Adiabatic tuning can immobilize and reverse sound pulses.

Principles are applicable across various scales and platforms.

Abstract

Slowing down, stopping, and reversing a signal is a core functionality for information processing. Here, we show that this functionality can be realized by tuning the dispersion of a periodic system through a dispersionless, or flat, band. Specifically, we propose a phononic metamaterial based on plate resonators, in which the phonon band dispersion can be modified from an acoustic-like to an optical character by modulating a uniform prestress. The switch is enabled by the change in sign of an effective coupling between fundamental modes, which generically leads to a nearly dispersion-free band at the transition point. We demonstrate how adiabatic tuning of the band dispersion can immobilize and reverse the propagation of a sound pulse in simulations of a one-dimensional resonator chain. Our study relies on the basic principles of thin-plate elasticity independently of any specific material, making our results applicable across varied length scales and experimental platforms. More broadly, our approach could be metamaterials and electronic heterostructures.