Propagation of acoustic surface waves on a phononic surface investigated by transient reflecting grating spectroscopy

TL;DR

This study investigates surface acoustic wave propagation on a 1D phononic surface using transient reflecting grating spectroscopy, revealing multiple Bloch wave modes and their dispersion characteristics beyond the first Brillouin zone.

Contribution

It provides experimental characterization and numerical analysis of multiple SAW modes on a phononic surface, advancing understanding of their dispersion and surface localization.

Findings

Four distinct SAW frequencies identified with articulated dispersion.

SAWs are characterized as four Bloch waves with different surface localizations.

Propagation on flat surface differs from phononic surface, highlighting phononic effects.

Abstract

We present a study of surface acoustic waves (SAW) propagation on a 1D phononic surface (PS) by mean of an heterodyne-detected transient reflecting grating experiment. We excited and detected coherent stationary SAWs characterized by variable wave-vectors. The measured SAW frequencies enables the characterization of the band diagram of this PS sample beyond the first Brillouin zone (BZ). Four different SAW frequencies have been revealed, whose band diagram show articulated dispersion phenomena. In order to address the nature of the investigated SAWs, the experimental results are compared with a numerical simulation of elastic modes based on a finite element model. The observed SAWs are addressed to four Bloch waves characterized by different frequencies and surface energy localization. Moreover, we measured the SAW propagation on a flat non-phononic part of the sample surface and compared it with results from the PS.