Stimulated hyper-Raman scattering in a molecular gas via a three-photon process to obtain IR and far IR radiation

The laser, Raman, and hyper-Raman processes are studied in a three-wave four-level system by means of a numerical analysis of the steady-state density matrix equations. Gain spectra curves are presented for IR-IR and IR-MW pumped systems and for two four-level systems in NH
3
that yield 12.159 and 12.114 μm wavelength radiation. Using the gain spectra data, threshold pump intensities, output intensities, ac Stark shifts,
M
splittings, optimum NH
3
pressures, and saturation are studied. The theoretical data agrees with the experimental data well within a factor of two. It is shown that the hyper-Raman process can lead to higher power, frequency stable, optically pumped lasers.