Investigation of tunable stimulated Raman scattering by light mixing in liquid N2

High-order tunable anti-Stokes Raman scattering is produced by mixing the radiation of a Q-switched ruby laser and that of a dye laser in liquid nitrogen. All investigated orders of both ruby laser and dye laser anti-Stokes radiation are found to have the same ruby laser power threshold of about 0.5 MW. The intensities of the anti-Stokes radiation are found to increase linearly with ruby laser power once threshold has been surpassed appreciably. The dye laser anti-Stokes radiation does not exhibit a dye laser threshold power. The results can be explained by a simple theoretical model which treats the ruby laser as a pump for coherent molecular oscillations.