Nonlinear Evolution of Stimulated Raman Backscatter in Cold Homogeneous Plasma

We present an analytic solution for Raman backscatter in a cold homogeneous plasma, valid until saturation by breaking of the longitudinal waves, or by self-consistent depletion of the pump. We give quantitative values for the pump strength necessary for the former to occur first, and the transmission at saturation. Nonlinear particle bunching causes growth of electromagnetic sidebands. In quarter-critical plasma, a sideband at $\omega =\frac{3}{2}{\omega }_0$ reaches 8% of the pump intensity at wave breaking.