Photorefractive materials for nonvolatile volume holographic data storage. Science

Optically gated recording and nonvolatile readout in a digital volume holo-graphic data storage system that uses a pair of mutually incoherent light sources during recording and only one for readout were demonstrated recently. This approach used stoichiometric lithium niobate, which after post-growth processing gave rise to an at least two orders of magnitude improvement in sensitivity over the best materials reported previously. It is also shown that by adding certain dopants (iron and manganese) to near-stoichiometric lithium niobate, the dark storage time and gating efÞciency can be increased compared with previous work. The underlying physical mechanisms of gated recording and the effectiveness of the gating process responsible for this manifold improved performance are discussed, and bipolarons and small polarons are identiÞed as the responsible photorefractive species. Holographic data storage systems have long held promise for their high storage capacity, short access times, and high data transfe