Stimulated Brillouin scattering (SBS) in single mode fibre optic resonators

Stimulated Brillouin Scattering (SBS) is an important nonlinear effect which is observed in single mode optical fibres at relatively low input powers. By using high finesse all-fibre single mode resonators, extremely low pump powers can be used and very low Brillouin thresholds can be demonstrated. Fabrication of the resonator from polarisation maintaining fibre helps to ensure that the pump and the Stokes waves are polarisation matched and further reduces the Brillouin threshold by a factor of 2. The two halves of the polished coupler have to be aligned on the same fibre axes to ensure a low level of polarization cross-coupling. For the resonators used in the experiments better than -25 dB polarization cross-coupling has been achieved