Frequency up-conversion by stimulated hyper-Raman scattering

Stimulated electronic hyper-Raman scattering has been obtained in lithium vapor via excitation of several two-photon resonances (2s-3d, 2s-4s, 2s-4d) with a pulsed dye laser. The wavelength of the generated radiation was shorter than the pump wavelength and tunable over a few nanometers. The tuning behavior of the hyper-Raman laser was influenced by two-photon induced self-focusing/self-defocusing effects.