Theory of spin-flip laser modes - II: Higher modes and saturation effects

Results are presented for the threshold input power and tuning characteristics of the higher (transverse) modes of the spin-flip Raman laser. It is concluded that the fundamental mode has the lowest threshold for all cases of interest in the model which we have used. Effects of spin saturation on the fundamental mode are also analyzed, leading to an estimate of the magnitude of the variation of output frequency with input power. Coexistence of longitudinal modes in the vicinity of a mode hop is considered, but the conclusions are obscured by lack of knowledge of the relevant magnetic diffusion lengths.