Ferroelectric-photoconductor optical storage medium utilizing bismuth titanate

Abstract

A basic feasibility study has been made on a ferroelectric-photoconductor optical storage medium utilizing bismuth titanate and zinc selenide. Both the theory of device operation and experiment are described. Coincident light and electric field are used for WRITE and ERASE functions. The nondestructive READ operation is based on the birefringence properties of the bismuth titanate. Optical-electrical measurements, pattern storage and hologram storage are described. Holographic gratings as fine as 1.261 were stored. The WRITE energy was approximately lOpJ/(mm)'. Diffraction READ effciencies of approximately .01% were measured. The ferroelectric photoconductor optical storage medium compares favorably with other erasible media.

Holographic recording and beam coupling in ferroelectricBi4Ti3<

“…It can be clearly seen that the intensity changes of both beams have opposite phase and different amplitudes, which indicates that refractive-index as well as absorption gratings coexist. As described by Sutter and Günter, 9 if the translation time is much shorter than the time needed to build up a new grating, and under the condition that the diffraction efficiencies are small, the sum ͓I ϩ (x)͔ and the difference ͓I Ϫ (x)͔ of the intensities of both interacting beams (I (1) and I (2) ) behind the crystal can be written as…”

“…1 In the past, it was extensively studied for ferroelectric optical memory devices. 2,3 But up to now there is no report on the photorefractive properties of this crystal to our knowledge. In this paper we report our experimental studies on holographic recording and beam coupling in Bi 4 Ti 3 O 12 .…”

Photorefractive properties ofBi4Ti3X1, Xu2, Mersch3 et al. 1997Phys. Rev. B

“…It has interesting electro-optical properties and was studied for ferroelectric optical memory devices in the 1970s. 2,3 In a previous paper we reported for the first time, to our knowledge, that holographic gratings can be written in ferroelectric Bi 4 Ti 3 O 12 crystals via the photorefractive effect and presented results on holographic recording and beam coupling. 4 Our recent experiments with this material revealed a very fast photoinduced process in holographic recording that was not recognized in the previous investigation.…”