Study of non-linear optical phase conjugation in Ca by resonant degenerate four-wave mixing via bound excited states

. The dependence of the reflectivity on the vapour density, the buffer gas pressure and the pump beams intensity was investigated. The influence of the strong linear absorption was taken into account in a theoretical model that led to a satisfactory interpretation of the experimental results. A maximum reflectivity of 46% was measured under optimized conditions. The effect was also studied through the high-lying bound states . The maximum measured reflectivity was as high as for the first excited state. The effect of the oscillator strength on the reflectivity was demonstrated experimentally and interpreted with the help of a simple theoretical model.