Writing and copying in volume holographic memories: Approaches and analysis

We analyze and compare three approaches for volume holographic writing/copying in photorefractive media. These include the parallel, incremental, and sequential approaches. We show that the three approaches' achievable grating modulations and total writing/copying times are identical. We then go on to discuss schemes within each approach by which the copying of one volume holographic memory into a secondary volume holographic memory can be optimized. These include all optical, quasi- all optical, and opto-electronic schemes. In this analysis, realistic material and device limitations are considered. Our calculations indicate that all optical copying in the parallel approach is the worst option, but opto-electronic copying in the sequential approach is the best option.