TRANSIENT ANALYSIS OF DEGENERATE 4-WAVE-MIXING WITH ORTHOGONALLY POLARIZED PUMP BEAMS IN A SATURABLE ND-YAG AMPLIFIER

Degenerate four-wave mixing with orthogonally polarized pump beams at lambda = 1.06 mum in the saturable gain of a flash-lamp-pumped Nd:YAG amplifier is investigated, both experimentally and theoretically, usin g pulses of duration much less than the population relaxation time. We introduce a new set of coupled-wave equations in this short pulse reg ime that includes the effect of the four interacting waves and the las er gain experienced by all the beams. The dependence of the efficiency of the process on the small-intensity-gain-length product, beam ratio s, and fluences is analyzed. A reflectivity of a weak probe beam of 25 percent and a transmission-gain-grating diffraction efficiency of 32 percent are achieved. Finally, the temporal shape of the conjugate sig nal is studied for various gain-saturation regimes.