Limitations on holographic storage capacity of photochromic and photorefractive media

Abstract

The erasure, which occurs during readout of holograms in photochromic or photorefractive media, imposes limitations on the amount of information which can be stored. It is shown that storage of several holograms by varying the angle of incidence of the reference beam is particularly unfavorable. It is much more advantageous to use a large number of bits per page or to store the holograms in separate parts of the sample. If erasure is prevented by some kind of physical or chemical fixing or biasing process, the storage capacity is limited by the bit rate required during readout. This limitation may also be severe, in some cases reducing the storage capacity to several orders of magnitude below the diffraction-limited value.