Simplified setup for Brillouin scattering observation using variable reflectivity mirror and its polarisation characteristics

Abstract

The authors present a streamlined setup for Brillouin scattering observation, which negates the need for an independent reference path by incorporating a variable reflectivity mirror at the terminus of the sensing fibre. The authors’ study uncovers an optimal reflectivity point, specifically at −9 dB, where the signal‐to‐noise ratio (SNR) of the observed Brillouin gain spectrum (BGS) reaches its zenith, approximately doubling the SNR of a conventional simplified setup that utilises Fresnel reflection. Furthermore, the authors elucidate that this setup inherently mitigates the polarisation‐dependent fluctuations of the BGS.