LONGITUDINAL, DEGENERATE, AND TRANSVERSAL PARAMETRIC OSCILLATION IN APHOTOREFRACTIVE MEDIA

We present a theoretical model of photorefractive parametric oscillati on that covers, for the first time, to our knowledge, the occurrence o f the whole spectrum of parametric processes from transversal over deg enerate to longitudinal parametric oscillation. It is shown that inclu sion of so-called noneigenwaves is essential for completing tile model . We report on the first experiment that shows the transition from tra nsversal over degenerate to longitudinal parametric oscillation. The e xperimental observations agree well with the theoretical predictions.