1 150km Range Distributed Temperature Sensor Based on Coherent Detection of Spontaneous Brillouin Backscatter and in line Raman amplification

Abstract: We report an extended range distributed temperature sensor based on coherent detection of the frequency shift of the spontaneous Brillouin backscatter combined with Raman amplification. The Raman amplification was achieved within the sensing fibre using either co- or counter- propagating Raman pump with respect to the probe pulse and experiments were conducted to investigate the optimum pump and probe power combination. With a co-propagating Raman pump a temperature resolution of 0.8ºC was achieved at a sensing range of 100km and with counter- propagating Raman pump a temperature resolution of 5.2ºC was achieved at a sensing range of 150km with 50m spatial resolution. Copyrigh