Stimulated Brillouin scattering revisited: Strong coupling regime and Rabi splitting

TL;DR

This paper revisits stimulated Brillouin scattering theory, demonstrating that strong coupling between optical and acoustic waves leads to Rabi splitting, which could be observed in tapered optical fibers under certain conditions.

Contribution

It introduces a joint system model showing strong coupling effects and Rabi splitting in stimulated Brillouin scattering, expanding understanding of light-acoustic interactions.

Findings

Strong coupling regime causes avoided crossing and Rabi splitting.

Rabi splitting can be observed in tapered fibers with moderate power.

Theoretical framework for optoacoustic strong coupling is established.

Abstract

Stimulated Brillouin scattering in optical waveguides is a fundamental interaction between light and acoustic waves mediated by electrostriction and photoelasticity. In this paper, we revisit the usual theory of this inelastic scattering process to get a joint system in which the acoustic wave is strongly coupled to the interference pattern between the optical waves. We show in particular that, when the optoacoustic coupling rate is comparable to the phonon damping rate, the system enters in the strong coupling regime, giving rise to avoided crossing of the dispersion curve and Rabi-like splitting. We further find that optoacoustic Rabi splitting could in principle be observed using backward stimulated Brillouin scattering in sub-wavelength diameter tapered optical fibers with moderate peak pump power.