Stimulated Brillouin Scattering in layered media: nanoscale enhancement of silicon

TL;DR

This paper presents a theoretical analysis of Stimulated Brillouin Scattering in layered anisotropic media, predicting a significant nanoscale enhancement of SBS gain in silicon-based composites due to combined physical effects.

Contribution

It introduces a comprehensive theoretical framework for SBS in anisotropic layered media and predicts a substantial nanoscale SBS gain enhancement in silicon-based composites.

Findings

Layered silicon and As₂S₃ glass media exhibit a 500-fold increase in SBS gain.

Theoretical prediction of a SBS gain of 1.28×10⁻⁹ W⁻¹·m in the composite.

Enhancement arises from roto-optic, photoelastic, and artificial photoelastic effects.

Abstract

We report a theoretical study of Stimulated Brillouin Scattering (SBS) in general anisotropic media, incorporating the effects of both acoustic strain and local rotation in all calculations. We apply our general theoretical framework to compute the SBS gain for layered media with periodic length scales smaller than all optical and acoustic wavelengths, where such composites behave like homogeneous anisotropic media. We theoretically predict that a layered medium comprising nanometre-thin layers of silicon and As$_2$S$_3$ glass possesses a bulk SBS gain of $1.28 \times 10^{-9} \, \mathrm{W}^{-1} \, \mathrm{m}$. This is more than 500 times larger than the gain coefficient of silicon, and substantially larger than the gain of As$_2$S$_3$. The enhancement is due to a combination of roto-optic, photoelastic, and artificial photoelastic contributions in the composite structure.