Observation in wave-number space of pump-beam replication in stimulated Raman scattering

Stimulated Raman scattering has been proposed for use in beam combining. In one configuration, several crossing pump beams are combined by amplifying a centrally seeded Stokes beam. Experiments show that a moderate level of pump-beam aberrations can give rise to beam replication, i.e., Stokes generation along the paths of the pump beams. The underlying physical mechanism could be nonlocal four-wave mixing or pump beam scintillation. A numerical scheme is used here that allows one to identify the individual gain contributions from different regions of wave-number space, which confirms that scintillation is primarily responsible for beam replication.