“…Since the discovery of the photorefractive efFect in III-V [1,2] and II-VI [3] compound semiconductors, applications of this effect are considered in information transmission [4] and processing [5], beam cleanup [6), laser system design 7], or characterization of semiconductor materials [8,9] using two-wave mixing (TWM) and four-wave mixing (FWM) schemes. High gain coefficients were recently obtained in GaAs [10] and InP [11,12] and used in self-starting oscillators [13,14], in analogy to earlier experiments with photorefractive oxides.…”