The vast possibilities of optical data processing can not be fully realized due to the absence of function transformation methods of optical signal. One of the principal elements of such transformation is the on-line optical storage device. A large number of studies has been presently carried out on creation of memory elements based on electro- optical crystals. All crystals can be divided into two large groups: the first group includes crystals in which electrical information is recorded and the reading is carried out by optical means; the second group includes crystals in which two-dimensional optical signals are stored. The different physical nature of optical memory in these two crystal groups results in certain limitations of its realization in practical devices and, therefore, of its application field. Duration of information storage under conditions of optical memory realization sufficiently depends on the nature of electro-optical effect. Depending on the crystal being used the optical memory may vary from 10-10s (semiconductors) to infinite storage time (ferroelectrics), i.e. these crystals possess both operative and fixed storage.
Anatoly A. Berezhnoy,
Yury G. Popov,
"Optical memory in electro-optical crystals", Proc. SPIE 1401, Optical Data Storage Technologies, (1 March 1991); doi: 10.1117/12.26135; https://doi.org/10.1117/12.26135