EFFECTS OF ATOMIC MOTION ON THE POLARIZATION PROPERTIES OF PHASE CONJUGATION BY 2-PHOTON-RESONANT DEGENERATE 4-WAVE-MIXING

We have studied the polarization properties of phase conjugation by degenerate four-wave mixing utilizing the 3S-->4S two-photon-allowed transition of sodium. We have observed high-fidelity vector phase conjugation (simultaneous conjugation of the optical wave front and the state of polarization) at a reflectivity of approximately 1% for the case where the states of polarization of the two counterpropagating pump waves were circular and counterrotating. High-fidelity polarization conjugation with high reflectivity was obtained only when the forward pump wave was much stronger than the backward pump wave. To explain these results, it is necessary to include the effects of grating washout due to atomic motion in the theoretical analysis.