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Phase conjugation in LiF and NaF color center crystals

A detailed experiment on phase conjugation via degenerate four-wave mixing in LiF:F2- and NaF (F2+)* crystals pumped by pulse-periodic Nd:YAG laser is described. The dependence of the efficiency of phaser conjugation on the energies and polarizations of the interacting beams and on the concentration of F2- CC is described. The mechanism of phase conjugation is connected with the saturation of the absorption in the color center crystals. Phase conjugation was investigated in LiF:F2- crystals that worked simultaneously as a passive Q-switch of a Nd:YAG laser. This allows use of the LiF:F2- crystal as a phase conjugated mirror of a Nd:YAG laser.