Abstract

All broadband, multimode Raman scattering experiments are performed with mode spacing smaller than the Raman linewidth.^1-3 Different models have been used to explain the experimental results. Transient stimulated Raman scattering (SRS) theory⁴ can be used in the un-depleted pump regime. However, it is hard to infer any physical insight or scaling laws from these data without performing a lengthy parameter study for a multimode, broadband light. In the limit of the wide-mode spacing (as compared to the Raman linewidth), SRS equations were solved in the Fourier space.^3–6 Under these conditions, it is also possible to extend the theory to include pump depletion.⁶ Most experimental results are modeled by this theory, because it provides a convenient closed-form solution; some of the parameters include total laser bandwidth and correlation between pump and Stokes. However, wide-mode spacing theory shows negligible gain for the uncorrelated pump and Stokes beams, which contradicts the experimental results and which, by definition, should not be used to model existing experiments.

© 1991 Optical Society of America