SPATIAL EVOLUTION OF THE PHASE IN RESONANT DEGENERATE 4-WAVE-MIXING

A theoretical investigation of phase conjugation via transient degener ate four-wave mixing in saturable-gain media is presented. A set of co upled wave equations that considers the spatial evolution of both, amp litude and phase is formulated and numerically analysed for the on and off-resonance case. It is shown that phase evolution is exclusively p roduced by a phase grating and that this grating does not affect the f our beams in the same manner. A necessary condition for phase conjugat ion is derived. A group theory analysis is applied to identify SU(2,2) as the underlying symmetry of the transmission grating model.