READ-WRITE HOLOGRAPHIC MEMORY WITH IRON-DOPED LITHIUM NIOBATE

摘要

The response of iron-doped lithium neonate under conditions corresponding to hologram storage and retrieval is described, and the material's characteristics are discussed. The optical sensitivity can be improved by heavy chemical reduction of lightly doped crystals such that most of the iron is in the divalent state, the remaining part being trivalent. The best reduction process found to be reproducible so far is the anneal of the doped crystal in the presence of a salt such as lithium carbonate. It is shown by analysis and simulation that a page-oriented read-write holographic memory with 103 bits per page would have a cycle time of about 60 ms and a signal-to-noise ratio of 27 dB. This cycle time, although still] too long for a practical system, represents en improvement of two orders of magnitude over that of previous laboratory prototypes using different storage media.