Intensity saturation of stimulated Raman scattering by ion-wave coupling.

Nonlinear saturation of stimulated Raman scattering caused by ion-wave coupling is investigated analytically and numerically. Various linear damping conditions for plasmons and ion-acoustic waves are included in the analysis. The main results can be summarized in terms of the normalized damping coefficient β (β=Raman gain length/plasmon absorption length), which decreases with the laser intensity I as β∼I-1/2. At low intensities (β>4) the Raman reflectivity increases according to the well-known three-wave process. At high intensities (0.2<β<2) a steady state still exists and the reflectivity is saturated as a function of the laser intensity. At very high intensities (β<0.1) temporally spiky and chaotic reflectivity is obtained. The reflectivities remain at very low levels, except for large interaction lengths. [ABSTRACT FROM AUTHOR]