Abstract

Photorefractive materials are promising candidates for optical storage¹ because of their unique capability to implement write/read volume holographic memories. Multiple holograms can be recorded in a photorefractive crystal sequentially by using an exposure schedule² that equalizes the amplitudes. It is important to note that undesirable noise gratings are formed during the recording of multiple holograms. These noise gratings are induced by the diffracted beams from previously recorded holograms and the writing beams. The formation of additional noise gratings may be especially problematic in optical memory applications, where a large number of gratings are superimposed in a photorefractive crystal. In this paper, we consider the formation of photorefractive noise gratings and its effect on the signal-to-noise ratio. The results indicate that the noise gratings can be minimized by increasing the Bragg mismatch between the gratings.

© 1992 Optical Society of America