<title>Stabilized Brillouin fiber ring laser (BFRL) using low-loss fused single-mode resonator couplers for application in distributed fiber sensor systems</title>

Abstract

Low loss fused single-mode fibre couplers for high finesse ring resonators (finesse 150 .. 300) have been manufactured for use in the BFRL. The fused fibre couplers have coupling ratios from 1 .2 % to 5% with excess loss less than 0.009dB ( <0.2 %). These components represent the passive part of an all-fibre Brillouin ring-laser pumped by a Nd:YAG-laser @X= 1319nm wavelength. With FM-sideband modulation technique [1 ,2 we stabilized the round trip wave in the ring resonator RRes, adjusting actively the laser frequency by a thermoelectric cooler and a piezoelectric element. Above pump threshold (about 1 1OjtW at 40m fibre length and finesse= 132) the RRes starts stimulated Brillouin backscattering. This 13GHz-frequency-shifted-BFRL light source can be used as a probe laser for Brillouinsensing in a Brillouin optical-fibre time domain analysis (BOTDA) measurement setup.