Holography for information storage and processing

We review recent progress made towards two types of holographic data storage systems. The first offers the potential for simultaneous search of an entire database by performing multiple optical correlations between stored data pages and a search argument [1,2]. This content–addressable retrieval produces one analog correlation score for each stored volume hologram. We review work we have performed on fuzzy encoding techniques, experimental demonstrations of hardware–level database searching, on the measurement of true inner–products, on architectures in which massively– parallel searches could be implemented [3], and on quantifying the inherent speed–fidelity tradeoffs [4]. The second system offers read–write, fast–access data storage. We review systems architectures for extending this high density to high capacity using phase–conjugate readout [5] and signal processing to relieve alignment and distortion constraints [6].