We report on a novel method for simultaneous distributed measurement of temperature and strain based on spatially resolving both spontaneous Raman and Brillouin backscattered anti-Stokes signals. The magnitude of the intensity of the anti-Stokes Raman signal permits the determination of the temperature. The Brillouin frequency shift is dependent on both the temperature and the strain of the fiber; once the temperature has been determined from the Raman signal, the strain can then be computed from the frequency measurement of the Brillouin signal.

We demonstrate enhanced performance of a single-ended spontaneous-Brillouin-intensity-based distributed-temperature sensor with a sensing length of 50 km and a spatial resolution of 15 m by use of Raman amplification of the probe pulse within the sensing fiber. The Raman amplification was achieved with a copropagating pump pulse at 1450 nm. The standard deviation error of the temperature resolution was 1 degree C at the front end and increased to less than 13 degrees C at 50 km with Raman pulse amplification.

A remotely pumped EDFA combined with Raman amplification was used to enhance the performance of spontaneous Brillouin intensity-based temperature sensor. A temperature resolution of 5.7 C, spatial resolution of 20m was achieved at 88km.

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The relative accuracy of temperature and strain determination using Brillouin frequency shift and power change in standard single-mode fibre and the frequency shifts of the two Brillouin peaks in large effective area fibre is reported.