Ferroelectric information optical storage device with self biasing
AssigneeThomson-CSF
InventorsJean Pierre Huignard, Francois Micheron
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Abstract
For amplifying the photosensitivity of a ferroelectric crystal in which information is to be stored, an external field applied to the crystal is created by means of a heavily doped, reduced photocell crystal illuminated uniformly by radiation within the absorption band of the crystal. The photocell crystal connected to the terminals of the lightly doped, non-reduced ferroelectric crystal, of which the resistivity is very much higher than that of the photocell crystal, develops a very high voltage which relaxes with a high time constant. Such a voltage increases the variations in the birefraction of the ferroelectric crystal.
Claims6
An information optical storage device comprising a lightly doped non-reduced ferroelectric cyrstal for holographic storage of information, a heavily doped reduced photocell crystal, having an absorption frequency band, adapted for being photoexcited by means of a uniform luminuous radiation having a frequency band within said absorption band, said photocell crystal thus producing an electrical field, and direct connecting means for applying said electrical field to said ferroelectric crystal, being formed by the common edge between the two crystals and by a conductor wire connecting the two faces opposite the said common edge, said ferroelectric crystal having a very much higher resistivity than said photocell crystal.
Dependencies are inferred from the claim text.