Transmodal Fabry-P\'erot Resonance: Theory and Realization with Elastic Metamaterials

TL;DR

This paper introduces a novel transmodal Fabry-Pérot resonance in elastic media, where one elastic wave mode is maximally transmitted to another, confirmed through experiments with elastic metamaterials.

Contribution

It presents the first theoretical and experimental demonstration of transmodal Fabry-Pérot resonance involving coupled elastic modes in anisotropic media.

Findings

Discovered the conditions for transmodal resonance involving phase difference of π.

Confirmed the phenomenon experimentally with elastic metamaterials.

Identified structural instability as a cause of transmission spectrum features.

Abstract

We discovered a new transmodal Fabry-P\'erot resonance that one elastic-wave mode is maximally transmitted to another when the phase difference of two dissimilar modes through an anisotropic layer is exactly odd multiples of {\pi}. Unlike the well-established Fabry-P\'erot resonance, the transmodal resonance must involve two coupled elastic-wave modes, longitudinal and shear. The formation of wiggly transmodal transmission spectra is due to structural instability appearing in anisotropic mode-coupled elastic-media. Experiments with elastic metamaterials confirmed our findings which can play a critical role in shear-mode ultrasound applications.