Optical: systems and elements – Holographic system or element – Having particular recording medium
Patent
1995-04-10
1997-07-15
Henry, Jon W.
Optical: systems and elements
Holographic system or element
Having particular recording medium
359 24, 359 3, G02B 102, G02B 500, G02B 104
Patent
active
056488564
ABSTRACT:
A method and read/write memory based thereon for storing phase holograms in a photorefractive crystalline material in which electric-field-mobile positive ions are associated with certain sites within the material broadly characterized by first forming a halogram (light interference pattern) in the material in order to redistribute the electrons therein to cause variations of the electric fields which variations represent the halogram, and then illuminating the material with light of a frequency in an absorption band of the ionic bond and having sufficient energy to cause the positive ions to be redistributed to neutralize the electric field variations caused by the electrons, whereat said positive ions remain fixed. As applied to a specific crystalline material, Fe:LiNbO.sub.3, having protons held in OH.sup.- bonds, a crystal of Fe:LiNbO.sub.3 is exposed to a light interference pattern to record the same as an electronic space charge pattern or hologram in the volume of the crystal by photo-excitation of electrons trapped at Fe+2 sites. Afterwards, or at the same time, the crystal is exposed to light at a proton absorption band in order to optically liberate the protons from OH.sup.- bonds within the Fe:LiNbO.sub.3 and, thereby, to neutralize the electronic pattern or halogram space charge and allow the protons to migrate and to create a proton space charge pattern which mirrors the electronic pattern or halogram and neutralizes the space charge patterns of the electrons. Thereafter, the protons remain fixed.
REFERENCES:
patent: 3773400 (1973-11-01), Amodei et al.
patent: 3873179 (1975-03-01), Burke
patent: 4124268 (1978-11-01), Micheron et al.
Staebler D. L. et al. "Thermally fixed holograms in LiNbO.sub.3 " Ferroelectrics, vol. 3, (1971) p. 107.
Staebler D. L. et al. "Multiple Storage and Erasure of Fixed Holograms in Fe-doped LiNbO.sub.3 " Appl. Phys. Ltrs. vol 26, No. 4 (15 Feb. 1975) pp. 182-184.
Mott, N. F. et al., Electronic Processes in Ionic Crystals Oxford 1957 pp. 40-45.
von der Linde, D. et al., "Multiphoton photorefractive processes for optical storage in LiNbO.sub.3 " Appl. Phys. Ltrs. vol 25, No. 3 (1 Aug. 1974) pp. 155-157.
von der Linde, D., et al., "Optical storage using refractive index changes induced by two-step excitation" Journal of Appl. Phys. vol 47, No. 1 (1 Jan. 1976) pp. 217-220.
Amodei, J. J., et al. "Holographic Pattern Fixing in Electro-Optic Crystals" Appl. Phys. Ltrs. vol 18 No. 12 (15 Jun. 1971) pp. 540-542.
Klauer, S., et al., "Influence of H-D isotopic substitution on the protonic conductivity of LiNbO.sub.3 " Physical Review B, vol. 45 No. 6 (1 Feb. 92II) pp. 2786-2799.
Valley, G. C., et al., "Optimal properties of photorefractive materials for optical data processing" Optical Engineering vol. 22, No. 6 (Nov.-Dec. 1983) pp. 704-711.
Phillips, W., Burke, W.J., and Staebler, D.L., Final Report Contract N00019-76-C-0116 "Materials for Volume Phase Holography" (Dec. 1976) PRRL-76-CR-57 56 pages.
Anderson Terry J.
Henry Jon W.
Hoch Jr. Karl J.
Northrop Grumman Corporation
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