Suppression of polarisation-induced signal fluctuation in optic distributed sensing system based on stimulated Brillouin scattering

A new scheme capable of suppressing polarisation sensitivity in the Brillouin optical time domain analysis distributed sensing system is demonstrated. The polarisation-induced signal fluctuation is suppressed from >+300 μϵ(which causes measurement to fail) to +50 μϵ by introducing a cost-effective polarisation diversity scheme on the pump light. Stable distributed strain measurement along a 1.2 km singlemode fibre is achieved. This scheme needs no active component and the strain measurement time is only 3s.