Improvement of signal-to-noise capabilities of a distributed temperature sensor using optical preamplification

An optical preamplifier system consisting of a 27 dB-gain erbium-doped fibre amplifier, a three-port circulator and a 47 GHz bandwidth in-fibre grating has improved the optical signal-to-noise capabilities of a Brillouin-based fibre-optic distributed temperature sensor by 17 dB. Using this system and operating at 1533 nm, a sensor with a range of 23 km, spatial resolution of 1.8 m, measurement time of 9 min and temperature resolution of 6 K was implemented. The temperature resolution was attributed to contamination of the backscattered spontaneous Brillouin signal by the residual Rayleigh signal after optical filtering.