Infrared two-color Raman laser by four-wave Raman mixing

The generation of two-color 16-μm pulses by four-wave Raman mixing of TEA-CO2 lasers in para-H2 was studied. The equations based on combination of four-wave mixing and stimulated Raman scattering were solved numerically, under the assumption of focused Gaussian beams with pump power depletion. The prediction of the model was experimentally verified with a couple of pulses from independent TEA-CO2 lasers. Even a weak CO2 laser whose power is not intense enough to induce effective Raman conversion by itself was efficiently converted to the Stokes pulse by the Raman mixing. The influence of beam crossing in a multiple-pass cell and transient response of a medium on the conversion process are also discussed. (author)