Transient Raman amplification of spatially inhomogeneous laser beams

Theoretical and experimental investigations were made of the transient amplification of the Stokes component beams in hydrogen. The use of the pump and seed Stokes beams with deliberately matched spatial profiles makes it possible to increase the energy efficiency of the conversion to the Stokes component, compared with the efficiency when the interacting beams have similar profiles. Mechanisms limiting the efficiency of amplification of the Stokes component are discussed.