Abstract

The motivation for this work is to model the final Raman conversion stage of the SPRITE KrF laser system as the Rutherford Appleton Laboratory in which several pump beams propagating in a 1-m light guide at small angles to the axis amplify a Stokes pulse travelling down the axis.^1-2 The key merit of this configuration is that, in the long pulse regime at least, poor spatial coherence of the pump pulses is eliminated in the Raman conversion process. However, in many experiments, the duration of the KrF pulses is around 10 ps, significantly less than the 28-ps relaxation time of the Raman medium (methane); in this case, the interaction is therefore in the transient regime and the Stokes beam is no longer necessarily insensitive to phase variations in the pump.³

© 1994 IEEE