Infrared four-wave sum and difference frequency generation in liquid CO-O2 mixtures

Abstract
Four‐wave sum and difference frequency generation of the outputs of two CO2 TEA lasers are demonstrated in liquid CO‐O2 mixtures at 77 K. The efficiencies of these processes are enhanced by a two‐photon resonance with the CO vibrational mode. A study of the polarization dependence and the line shape of the two‐photon resonance is reported together with measurements of the mixing efficiencies. The difference frequency generation process can be phase matched using noncollinear phase matching.