Inelastic photon-phonon-interaction in Raman crystals gives rise for Stokes or anti-Stokes shift of pump radiation. It is so-called Stimulated Raman scattering (SRS). This is a versatile method for frequency conversion, which does not need to be phase-matched, features high conversion efficiency and easily compatible with current solid-state lasers. Suchlike Raman generator emission lines can cover wavelength range from UV to NIR due to cascaded SRS. For a selective Raman shift line amplification Raman crystal has to be placed into resonator with appropriate optical feedback.
4Lasers provide barium nitrate and undoped KGW, KYW Raman crystals. Do not hesitate to request custom, if desired crystals did not appear in the standard list.