Generation of radiation in a resonator under conditions of stimulated Raman scattering in Ba(NO3)2, NaNO3, and CaCO3 crystals

A study was made of the generation of Stokes radiation in plane-plane and unstable telescopic resonators under conditions of stimulated Raman scattering in calcite, barium nitrate, and sodium nitrate crystals. The regimes of effective operation of such Raman lasers were determined. It was shown that the efficiency of conversion of the energy of the pump radiation into the energy of the first Stokes component could be increased by ensuring repetitive passage of the pump along a crystal. It was found that the generation of the second Stokes component became weaker under the conditions of pumping of a crystal in an unstable telescopic resonator by a beam opposite to the Stokes radiation leaving the resonator. Measurements were made of the spatial and angular characteristics of the output radiation. In the case of pulsed generation of radiation in a plane-plane resonator it was possible to reduce the angular divergence by the use of a correcting positive (converging) lens.