STUDY OF NONLINEAR-OPTICAL PHASE-CONJUGATION IN CA BY RESONANT DEGENERATE 4-WAVE-MIXING VIA BOUND EXCITED-STATES

We have studied the optical phase conjugation (OPC) effect in Ca vapou r by using the resonant degenerate four-wave mixing (DFWM) technique. The effect was studied through the first excited state of Ca, 4s4p P-1 (1). The dependence of the reflectivity on the vapour density, the buf fer gas pressure and the pump beams intensity was investigated. The in fluence of the strong linear absorption was taken into account in a th eoretical model that led to a satisfactory interpretation of the exper imental results. A maximum reflectivity of 46% was measured under opti mized conditions. The effect was also studied through the high-lying b ound states 4p(2) P-3(0,1,2). The maximum measured reflectivity was as high as for the first excited state. The effect of the oscillator str ength on the reflectivity was demonstrated experimentally and interpre ted with the help of a simple theoretical model.