Abstract

Linear medium dispersion can reduce the stimulated Raman scattering gain for a broadband laser. This increases the Raman cell length required for Stokes frequency conversion and also limits the ultimate conversion efficiency achievable in a long cell. Modeling of these effects, particularly the latter one, must account for depletion of the pump laser intensity as it is converted. Inclusion of depletion effects into previous undepleted pump modeling efforts may be accomplished using a perturbation technique for weak dispersion. Numerical results for a 351-nm laser in 3.5 atm of hydrogen with a 1-nm bandwidth show that a fourth-order perturbation calculation is adequate to predict a conversion efficiency 9% below the quantum limit. The efficiency is found to decrease approximately quadratically with increasing bandwidth for bandwidths up to ~2.3 nm. An equivalent dispersion formulation may be used to extend these results to include the effects of a small angular misalignment between the pump and Stokes seed beams.

© 1988 Optical Society of America