Observation of the Talbot effect from a surface acoustic wave dynamic grating

TL;DR

This paper reports the experimental observation of the Talbot effect caused by surface acoustic waves using optical diffraction, revealing new amplitude modulation phenomena and confirming classical Talbot length behavior.

Contribution

It demonstrates the dynamical Talbot effect from surface acoustic waves and uncovers an amplitude-modulated term that enhances surface acoustic wave imaging techniques.

Findings

Amplitude-modulated term can exceed phase-modulated term in magnitude.

Optical Talbot effect observed despite curved wavefronts.

Amplitude modulation vanishes at specific acoustic wave positions.

Abstract

We demonstrate the dynamical Talbot effect caused by optical diffraction from standing surface acoustic waves (SAWs). The Talbot effect is a wave interference phenomenon in the Fresnel regime, and we observe it with a fiber-based scanning optical interferometer on a SAW Fabry-Perot cavity. By studying the interferometric signal at 1 GHz, we first discover the existence of an amplitude-modulated term, that can exceed in magnitude the usual phase-modulated term, enabling a new way of imaging surface acoustic waves. Secondly, by displacing the acoustic device from the beam focus we reveal the optical Talbot effect, where despite the curved wavefronts of the optical field, the conventional Talbot length appears. As a consequence, the amplitude modulation vanishes at periodic positions of the acoustic wave relative to the beam focus.