Self-focusing versus stimulated Brillouin scattering of laser pulses in fused silica

Abstract

The coupling between Kerr-induced filamentation and transient stimulated Brillouin scattering (SBS) is theoretically investigated for nanosecond laser pulses propagating in bulk silica. Power thresholds for beam collapse are evaluated by means of three-dimensional numerical simulations. It is shown that the nonlinear self-focusing of powerful pump waves is able to enhance the Stokes component to high fluence levels even if the incident beam exhibits a broad spectral bandwidth. In contrast, pump pulses with a few tens of picoseconds amplitude modulations drastically inhibit SBS. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.