Analysis of the wavelength dependence of Raman backscatter in optical fibre thermometry

Presents an analysis of the Raman backscatter for optical fibre distributed temperature sensors to quantify the effect of varying the pump wavelength. An optimal pump wavelength was found based on maximising the anti-Stokes backscattered power from the endpoint of the fibre. This optimum pump wavelength was found to vary as the fourth root of the distance to the endpoint of the fibre. The sensitivity of the system response to non-optimum pump wavelengths was also analysed. Results are presented for both direct detection and photon counting schemes.