Spontaneous Brillouin-based distributed temperature sensor utilizing a fiber Bragg grating notch filter for the separation of the Brillouin signal

We report on a Brillouin optical time domain reflectometer-based distributed temperature sensor utilizing a fiber Bragg grating notch filter to suppress the Rayleigh backscatter in order to separate the Brillouin signal. The Brillouin light path is thus subject to minimum attenuation and is frequency independent. A 2-m spatial resolution is achieved over a range of 25 km with the temperature resolution rising from 1/spl deg/C at the near end to 7/spl deg/C at the far end in a measurement time of 10 min. This is reduced to <1/spl deg/C over /spl sim/20 km if the measurement time is increased to 180 min.