A THEORETICAL COMPARISON OF SPONTANEOUS RAMAN AND BRILLOUIN BASED FIBER OPTIC DISTRIBUTED TEMPERATURE SENSORS

Present day commercially available fibre optic distributed temperature sensors exploit the temperature dependence of spontaneous Raman scatt ering. Spontaneous Brillouin scattering is also temperature dependent and provides a signal which is an order of magnitude greater. Advances in narrow bandwidth pulsed laser technology and low loss all fibre fi lters allow the Brillouin signal to be separated from the Rayleigh sig nal. Theoretical analysis now demonstrates that distributed temperatur e sensing based on Brillouin scattering offers considerably increased range beyond the theoretical limit of the spontaneous Raman based sens or. (C) 1997 Elsevier Science B.V.