Tunable parametric Raman laser utilizing polaritons in a lithium niobate crystal

Results are presented of an investigation of stimulated Raman scattering (STRS) by polaritons in a LiNbO₃ crystal with a Stokes wave resonator, which makes it possible to couple in the pump radiation at small angles down to zero. Tunable emission of Stokes radiation is reported in the 41–118 cm^–1 range. The maximum STRS gain corresponds to polariton frequencies of ~60 cm^–1. The frequency dependence of the gain causes the frequency-angular STRS spectrum to differ from the spontaneous scattering spectrum. Emission of the second Stokes component is interpreted as the result of cascade three- and four-photon nonlinear interactions.