Abstract

We analyze the three-dimensional refractive-index distribution that is induced locally when a laser beam is focused onto a very small region in a photorefractive crystal. The formation of the index distribution is deduced from the temporal behavior of the electron density distribution in the crystal under non-steady-state conditions. The density distribution is computed by the use of a set of the recurrence relations that was derived from Kukhtarev’s equations, which describe the transport of electrons in time. In particular, we calculated the index distribution formed in Fe-doped LiNbO₃ crystals. To verify the validity of our analysis, we read, by using a phase-contrast microscope, refractive-index dots that were recorded in Fe-doped LiNbO₃ crystals. Agood agreement was obtained between experimental results and the calculated phase-contrast images when the characteristics of the imaging system are taken into account. We also found that the induced index change is largest when the c axis of the LiNbO₃ crystal is oriented parallel to the polarization direction of the reading beam. Under this optimal condition, we succeeded in recording up to 10 layers of readable data in a LiNbO₃ crystal.

© 1996 Optical Society of America

Three-dimensional optical memory with a photorefractive crystal

Yoshimasa Kawata, Hisahiko Ueki, Yoshimi Hashimoto, and Satoshi Kawata
Appl. Opt. 34(20) 4105-4110 (1995)

Optical recording of reversed domains in a Ce-doped SBN:75 crystal for bit-oriented three-dimensional optical memory

M. Hisaka, H. Ishitobi, and S. Kawata
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Randomly accessible, multilayered optical memory with a Bi₁₂SiO₂₀ crystal

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Use of two-photon absorption in a photorefractive crystal for three-dimensional optical memory

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Comparison of recording densities in three-dimensional optical storage systems: multilayered bit recording versus angularly multiplexed holographic recording

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J. Opt. Soc. Am. A 13(5) 935-943 (1996)