Localized modes on a metasurface through multi-wave interactions

TL;DR

This paper investigates how localized elastic wave states emerge in a 2D metasurface made of beams on a plate, caused by multi-wave interactions and resonances, demonstrating a physical analogy to tight-binding coupling.

Contribution

It reveals the mechanism of localized state formation through multi-wave interactions and resonances in a 2D elastic metasurface, supported by experimental analysis.

Findings

Localized states arise from multi-wave interactions at beam-plate attachments.

Modal density drops near high-Q flexural resonances within the bandgap.

The system exhibits tight-binding-like coupling in the localized regime.

Abstract

In this paper, we describe the manifestation of localized states through coherent and incoherent analyses of a diffuse elastic wavefield inside a two-dimensional metamaterial made of a collection of vertical long beams glued to a thin plate. We demonstrate that localized states arise due to multi-wave interactions at the beam-plate attachment when the beams acts as coupled resonators for both compressional and flexural resonances on the metasurface. Due to the low-quality factor compressional resonance of the beams, inside the main bandgap the modal density of the systel drops to near a high-quality factor flexural resonance of the beams, and blocks the diffusion process of the wavefield intensity. This experiment physically highlights the tight-binding-like coupling in the localized regime for this two-dimensional metamaterial.