Phase conjugation of CO2 laser radiation in cryogenic liquids

An experimental investigation was made of phase conjugation of CO₂ laser radiation by a degenerate four-wave mixing in a cryogenic liquid of Kr:SF₆ composition. Periodic spatial modulation of the polarization of the liquid resulted from local vapor formation due to thermalization of the vibrational excitation of SF₆ molecules. An intensity reflection coefficient of ~ 300% was obtained in the long-wavelength wing of an absorption line of SF₆ when the pump energy density was 2 J/cm².