Browse Prior Art Database

Holographic Storage in Ferroelectric Ceramics

IP.com Disclosure Number: IPCOM000077010D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Pennington, KS: AUTHOR [+2]

Abstract

A new type of electric field-controllable holographic storage medium and optical storage device is disclosed.

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Holographic Storage in Ferroelectric Ceramics

A new type of electric field-controllable holographic storage medium and optical storage device is disclosed.

Holographic storage has recently been demonstrated using single-crystal pyroelectric or ferroelectric insulators as the storage media. Storage occurs as a consequence of periodic refractive index variations induced by the interference of reference and subject laser beams within the crystal volume, and is believed to be due to periodic local fields set up by the trapping of photoexcited charges at specific lattice sites. Crystals of Fe-doped LiNbO(3) and NaBa(2)Nb(5)O(15) have been used as storage media, and Ba(0.25)Sr(0.75)Nb(2)O(6) has been shown to display storage properties in the presence of an externally applied electric field. This effect is especially important, in that it could permit the writing of holograms at different fields and/or different angles of reference to subject laser beams, and subsequent reading of a given hologram at a specific field and/or angle.

Holographic storage in ceramics, i.e., polycrystalline materials is provided. Using a polished slab of the hot-pressed ferroelectric ceramic Pb(1- x)La(x)Zr(y)Ti(1-y)O(3) ("PLZT"), in which x = 0.12 and y = 0.40, a hologram is written with a 4880 angstroms argon laser in the presence of electric fields up to 10 kV/cm, applied perpendicular to the plane of the subject and reference beams. Storage occurs in the presence of the field only, and r...