Cascaded stimulated Brillouin scattering in high-finesse all-fibre ring resonators

One of the most dominant nonlinear effects in single-mode fibers is stimulated Brillouin scattering (SBS). The generation of SBS in a ring resonator can be considered as a lasing action, with the Stokes output downshifted in frequency by an amount equal to the Brillouin frequency. In the stationary case stimulated Brillouin scattering in a length of optical fiber can be described by the following partial differential equations for the slowly varying complex amplitudes of the pump wave E p and the backscattered first order Stokes wave E B1 , with the wave amplitudes E i related to the intensities I i by I i = |E i |2 (i=p,B1) [1]: (1) In a ring resonator geometry as depicted in Fig. 1 the wave amplitudes at the ports of the directional coupler obey the relations [2] (2) where V k 2 is the coupler intensity radiation loss, K is the field coupling coefficient, and T is the field transmission coefficient.