We propose a three-dimensional optical-memory device in which refractive dot data are recorded directly into a photorefractive crystal. To record a single bit of datum, one focuses a laser beam with an objective lens onto a specific spot in a crystal, thereby changing its refractive index locally as a result of photorefraction. To record in three dimensions, one keeps the objective lens stationary while the crystal is translated. The beam-spot intensity is modulated with a beam shutter according to the logic state of the data point. The recorded data points are read with a phase–contrast microscope objective lens. We present experimental results of three-dimensional recording and reading with a LiNbO3 crystal. The distribution of the refractive index formed by a focused beam is also analyzed with the charge-transport model.
© 1995 Optical Society of America
Original Manuscript: May 12, 1994
Revised Manuscript: November 28, 1994
Published: July 10, 1995
Yoshimasa Kawata, Hisahiko Ueki, Yoshimi Hashimoto, and Satoshi Kawata, "Three-dimensional optical memory with a photorefractive crystal," Appl. Opt. 34, 4105-4110 (1995)