Coupled longitudinal and transverse stimulated Brillouin scattering in single-mode optical fibers

Due to their finite numerical aperture, both longitudinal and transverse stimulated Brillouin scattering can occur in single-mode fibers. We discuss the role of the fiber structure and propose a coherent model accounting for both effects. We show experimentally and numerically that, in some cases, the perturbative cladding Brillouin scattering (CBS) can severely affect the dynamics of SBS Brillouin fiber lasers. New dynamical regimes of long-fiber Brillouin ring lasers are presented, including stable trains of modulated pulses.