Abstract

The storage of volume holograms in photorefractive crystals, such as lithium niobate, is of interest for mass storage of data and images. Grating formation in lithium niobate is usually modeled as a process of light induced diffusion of charge carriers setting up electric fields that cause variations in the index of refraction. In this work, the diffraction efficiencies of gratings were measured during and after exposure in order to determine the characteristic time scale of the diffusion. Diffusion times can be used to predict optimum grating spacings for the holograms. Applications of this work to the problems of reciprocity failure and optimizing diffraction efficiency will be discussed.

© 1992 Optical Society of America