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