Effects of scattering on photorefractive dynamics

Because of their high angular selectivities and diffraction efficiencies, photorefractive crystals are attractive media for implementing many optical-computing architectures. The temporal dynamics of the photorefractive effect must be understood before successful implementations of computing architectures using photorefractive multiplexed holograms can be realized. Previous theoretical analyses of the photorefractive effect have not taken losses into account. These losses result from absorption and/or scattering effects. When recording holograms in photorefractive lithium niobate, scattering is frequently a major effect, and the scattered power may exceed the diffracted power. It is therefore impossible to accurately match experimentaland theoretical results without including scattering in the theoretical analysis. Experimental investigations have monitored the dynamics of both the diffraction efficiency and the losses during the recording process in iron-doped lithium niobate crystals. After the dependence of the loss on the recording time is measured, a theoretical fit to the recording and erasure dynamics for single holograms may be accomplished. Our results will be presented and discussed, along with their influence on the recording of multiplexed holograms.