Stimulated Brillouin scattering threshold in double-clad fibers with various cladding shapes

We present a detailed numerical investigation about the stimulated Brillouin scattering (SBS) threshold power of double-clad optical fibers having different inner-cladding shapes. Generally, fibers with broken symmetry inner-cladding are usually employed in fiber lasers and amplifiers in order to enhance pump light absorption by the doped core. The acoustic response of such geometries is not known because their numerical characterizations are complicated. Even more difficulties occur when the fiber possess an acoustic anti-waveguide core since in that case the Brillouin response is often ruled by very high-order mode.