Coherent optical frequency reflectometer based on a self-scanning fibre laser for distributed measurements

Abstract: We report the possibility of measuring the temperature distribution along a conventional single-mode fibre by coherent optical frequency reflectometry using a self-scanning fibre laser and Rayleigh scattering of light by inhomogeneities frozen into the fibre. To this end, the problem of increasing the sensitivity of the reflectometer to a level of about –120 dB·mm^–1 is solved. A linear relationship is shown between a change in fibre temperature and a shift in the reflection spectrum of a heated fibre section 4 cm long with a sensitivity of ∼2 GHz·C°^–1.

Keywords: optical reflectometry, optical fibre, fibre laser, Rayleigh light scattering.