Experimental and theoretical study of non-volatile photorefractive holograms in doubly doped LiNbO3:Fe:Cu

We report the bleaching properties of iron and copper co-doped lithium niobate crystals that are candidates for nonvolatile holographic storage. In experiment, we propose a three-step recording/fixing scheme to realize non-volatile holographic storage in LiNbO3:Fe:Cu, which firstly uses two coherent red beams for recording, secondly one Bragg-matched red beam together with a uniform ultraviolet light for developing and thirdly a single red beam for fixing. In theory, we have considered not only the material response to the incidence light but also the response of the light to the medium. We present a theoretical model in which the two-center band-transport equations, the coupled-wave equations and the coherent readout are considered simultaneously. The time evolution of space-charge field and the optimal conditions for both processing and material prescriptions of holographic storage are analyzed numerically in detail. Which include the dopant concentrations, the oxidation/reduction states, the intensity ratio of the two red recording beams to the UN light. (C) 2002 Elsevier Science B.V. All rights reserved.