Influence of bidirectional cavity structure on the Brillouin Stokes signal characteristics in ring BFL

Abstract We experimentally demonstrate the effects of Brillouin amplifications on the stimulated Brillouin scattering threshold as well as the generated Stokes power. Brillouin fiber laser (BFL) ring cavity structure is used to show the effect of bidirectional signal propagation on threshold and Stokes power. The laser cavity is tested with conventional technique in which there is no signal circulation take place. Both structures are tested under the same experimental conditions using 5 km SMF length, threshold power for the 1 st Stokes signal is improved and reduced up to 90% in ring cavity structure compared to its value in conventional technique. The threshold is reduced, from the value of 16.2 mW in conventional structure to be 1.67 mW in ring laser cavity. Furthermore, different SMF lengths are tested and exhibits the same threshold reduction ratio. In addition, the 1 st and the 2nd Stokes signals within ring laser cavity are tested in terms of threshold and Stokes signals power. In addition, the induced Brillouin gain effect within a bidirectional ring cavity are studied on the maximum Brillouin Stokes signal power.