The filamentation effect in short pulse amplification by strong-coupling stimulated Brillouin scattering

The filamentation instability in strong-coupling stimulated Brillouin scattering (sc-SBS) amplification is investigated, and the growth rate and threshold power of filamentation are calculated. Theory and simulation results show that the filamentation instability destroys the amplified seed profile in sc-SBS amplification within a typical parameter region. An increase in the plasma density, which can increase the sc-SBS growth rate and avoid Raman scattering, exacerbates the filamentation instability. The relativistic effect is shown to be the main source of filamentation; however, introducing spatiotemporal incoherence into the seed pulse can greatly alleviate the filamentation instability.