THEORETICAL-STUDY OF SELF-STARTING GRATINGS IN PHOTOREFRACTIVE MULTIPLE-QUANTUM-WELL STRUCTURES

A model of wave mixing is developed for photorefractive multiple-quant um-well structures in quantum-confined Stark, effect geometry. This op tical model takes into account both absorption and index gratings and is based on the nonlocal character of the optical nonlinearity in the direction of the applied electric field. A coupling gain is defined th at depends only on the imaginary part of the relative permittivity gra ting, It is shown that self-starting gratings can appear when a certai n threshold condition on the coupling gain is verified, with this cond ition being similar to the threshold condition for double phase-conjug ate mirror operation in The possibility of obtaining with actual devic es the relatively high optical. nonlinearity necessary to reach the th reshold is discussed. Double phase conjugation with multiple-quantum-w ell structures in a two-zone configuration is envisaged. (C) 1996 Opti cal Society of America.