Stimulated rotational Raman scattering in air with diverging beam

Investigation on stimulated rotational Raman scattering (SRRS) in air with high power laser to seek suppression methods is one of the key issues which needs to be addressed in the construction of high-power solid-state laser driver. The evolution of SRRS with diverging beam is studied numerically. The threshold of the intensity-path-length product and the criterion to suppress SRRS using diverging beam are established by geometric approximation. The results show that the effect of SRRS grows slowly in diverging beam, choosing proper divergence angle can suppress SRRS effectively, and the angle depends on the beam size, laser intensity and propagation distance.