ABSTRACT
This chapter discusses the technology and performance of Raman distributed temperature sensor (DTS) systems. In fact, the onset of stimulated Raman scattering (SRS) often limits the amount of power that can be launched as a probe, and this effect ultimately limits the performance of Raman-based distributed temperature sensors. Backward SRS hardly affects Raman optical time-domain reflectometry (OTDR) systems because there is essentially no overlap between the spontaneous Raman scattering and the forward probe pulse. The remainder of the modulated light is launched into the sensing fibre via a dichroic device; as in Raman OTDR, the Raman backscatter signals in each of the bands are directed after optical filtering to separate detectors and preamplifiers. The underlying model assumes that the signals that are measured are purely due to Raman backscatter and that the system collects anti-Stokes and Stokes Raman backscatter signals. DTS technology using Raman backscattering in optical fibres is well developed and proven.
