Stimulated Raman Scattering by Polaritons

Stimulated Raman scattering from polaritons has been observed in LiNb${\mathrm{O}}_3$. The measured splitting of 134 ${\mathrm{cm}}^{-1\mathrm{}}$ between the 0° and 180° stimulated emission is in good agreement with infrared dispersion of the 628-${\mathrm{cm}}^{-1\mathrm{}}$ $A_1$ TO phonon. Threshold powers for the forward and backward stimulated emission are in fair agreement with the theory of polariton-stimulated Raman gain.