Approximate theory of Stokes amplification and conversion valid at large gain
Kai J. Drühl, Sadia Shakir, Maria Yousaf · Optics Letters · 1986
We predict Stokes-beam divergence, origin, and gain for large-gain Raman amplifiers as functions of pump-beam divergence and pump power in terms of simple analytical expressions. Stokes divergence is found to peak at a pump power twice above threshold. Results are in excellent agreement with exact computer solutions and explain recent experimental observations.