BGO relaxation dynamics probed with heterodyne detected optical transient gratings

TL;DR

This study investigates BGO crystal phonon dynamics using heterodyne-detected optical transient gratings, revealing acoustic oscillations and their parameters across various momenta, providing new insights into relaxation processes.

Contribution

It introduces a novel heterodyne detection method to probe BGO phonon relaxation dynamics with high spatial resolution and measures their properties across different momenta.

Findings

Identification of acoustic oscillations in BGO at room temperature.

Measurement of phonon dynamic parameters as a function of momentum.

Detection of oscillations in a previously unexplored time-frequency window.

Abstract

We used optical laser pulses to create transient gratings (TGs) with sub-10 {\mu}m spatial periodicity in a Bismuth Germanate (310) (Bi4Ge3O12) single crystal at room temperature. The TG launches phonon modes, whose dynamics were revealed via forward diffraction of a third, time-delayed, heterodyne-detected optical pulse. Acoustic oscillations have been clearly identified in a time-frequency window not covered by previous spectroscopic studies and their characteristic dynamic parameters have been measured as a function of transferred momenta magnitude and direction.