Abstract: A process for oxidizing iron ions contained within iron-doped lithium niobate. The process comprises the steps of protonating the iron-doped lithium niobate crystal and then placing the same into a pressure chamber where between 10-100 atmospheres of dry, ultra-pure pressurized oxygen are applied. While under pressure, the crystal is heated to approximately 950° C. at a rate not to exceed 50° C. per minute, and preferably at a rate not less than 25° C. per minute. The resulting lithium niobate crystal will thereafter contain iron ions wherein the divalent iron ion ratio to the trivalent iron ion ratio is approximately 1:100.

Abstract: A process for oxidizing iron ions contained within iron-doped lithium niobate. The process comprises the steps of protonating the iron-doped lithium niobate crystal and then placing the same into a pressure chamber where between 10-100 atmospheres of dry, ultra-pure pressurized oxygen are applied. While under pressure, the crystal is heated to approximately 950° C. at a rate not to exceed 50° C. per minute, and preferably at a rate not less than 25° C. per minute. The resulting lithium niobate crystal will thereafter contain iron ions wherein the divalent iron ion ratio to the trivalent iron ion ratio is approximately 1:100.

Abstract: A volume holographic memory has a spinning disk comprised of photorefractive medium, object beam optics configured to direct an object beam through the outer edge of the disk, and reference beam optics configured to simultaneously direct a reference beam through the outer edge of the disk. An angle multiplexer manipulates the reference beam to facilitate the formation of angle multiplexed volume holograms. The object beam and the reference beam cooperate within the photorefractive medium to sequentially form a plurality of sets of angle multiplexed volume holograms therein while the disk is spinning. A phase conjugator directs a conjugate reference beam back through the disk after the reference beam has previously passed therethrough, so as to form a conjugate object beam to facilitate read-out. Amplitude monitoring is provided to facilitate use of an exposure schedule. Path length monitoring assures consistent phase relationship between the object and reference beams for write and erase operations.

Abstract: A volume holographic memory has a spinning disk comprised of photorefractive medium, object beam optics configured to direct an object beam through the outer edge of the disk, and reference beam optics configured to simultaneously direct a reference beam through the outer edge of the disk. An angle multiplexer manipulates the reference beam to facilitate the formation of angle multiplexed volume holograms. The object beam and the reference beam cooperate within the photorefractive medium to sequentially form a plurality of sets of angle multiplexed volume holograms therein while the disk is spinning. A phase conjugator directs a conjugate reference beam back through the disk after the reference beam has previously passed therethrough, so as to form a conjugate object beam to facilitate read-out. Amplitude monitoring is provided to facilitate use of an exposure schedule. Path length monitoring assures consistent phase relationship between the object and reference beams for write and erase operations.

Abstract: A process for oxidizing iron ions contained within iron-doped lithium niobate. The process comprises the steps of protonating the iron-doped lithium niobate crystal and then placing the same into a pressure chamber where between 10-100 atmospheres of dry, ultra-pure pressurized oxygen are applied. While under pressure, the crystal is heated to approximately 950.degree. C. at a rate not to exceed 50.degree. C. per minute, and preferably at a rate not less than 25.degree. C. per minute. The crystals are then continuously heated at approximately 950.degree. C. for approximately 50 hours and then cooled to 30.degree. C. at a rate not to exceed 50.degree. C. per minute, and preferably at a rate not less than approximately 25.degree. C. per minute. The resulting lithium niobate crystal will thereafter contain iron ions wherein the divalent iron ion ration to the trivalent iron ion ratio is approximately 1:100.

Abstract: A volume holographic memory has a spinning disk comprised of photorefractive medium, object beam optics configured to direct an object beam through the outer edge of the disk, and reference beam optics configured to simultaneously direct a reference beam through the outer edge of the disk. An angle multiplexer manipulates the reference beam to facilitate the formation of angle multiplexed volume holograms. The object beam and the reference beam cooperate within the photorefractive medium to sequentially form a plurality of sets of angle multiplexed volume holograms therein while the disk is spinning. A phase conjugator directs a conjugate reference beam back through the disk after the reference beam has previously passed therethrough, so as to form a conjugate object beam to facilitate read-out. Amplitude monitoring is provided to facilitate use of an exposure schedule. Path length monitoring assures consistent phase relationship between the object and reference beams for write and erase operations.

Abstract: In a method for addressing holograms stored in a plurality of separate storage media, a reference beam is directed to a selected one of the plurality of storage media, the reference beam is then focused so as to obtain a substantially flat wavefront within a reference beam plane of the selected storage medium, and the angle of the reference beam is then varied so as to select a hologram stored therein.

Abstract: A method and system are disclosed for dynamically refreshing angle-multiplexed holograms stored in a photorefractive medium. In accordance with the invention the photorefractive medium is simultaneously exposed to a plurality of reference beams. Each reference beam is oriented at an angle corresponding to an angle at which a hologram was previously stored within the photorefractive medium. The frequency and duration of the reference beams are regulated such that each reference beam enhances the diffraction efficiency of an associated hologram, stored at the angle corresponding to the angle of the reference beam. Each reference beam is preferably at a frequency different from the frequency of the other reference beams so as to avoid the generation of plane-wave holograms due to interference between the multiple reference beams.

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.

Abstract: In a method for mitigating cross-talk in high-efficiency, angle-multiplexed holograms stored in photorefractive media, a plurality of uniformly low-efficiency holograms are first stored within a common holographic storage medium and then simultaneously exposed to a like plurality of mutually incoherent reference beams. Each reference beam effects enhancement of its corresponding hologram so as to increase the level thereof while also minimizing cross-talk between holograms.

Abstract: A pattern recognition apparatus and a method for operating same. The apparatus includes a volume holographic medium (4) having a plurality of Fourier-space volume holograms representing pattern templates stored within. The apparatus further includes a spatial light modulator (1) and a phase encoder (2). The phase encoder has an output optically coupled to the medium by a first Fourier transform lens (3). The spatial light modulator spatially modulates a spatially uniform laser beam (7) in accordance with an unknown pattern. The two-dimensional phase encoder causes the spatially modulated laser beam to be spatially distributed prior to application to the medium. The apparatus also includes a detector (6, 11) having an input optically coupled by a second Fourier transform lens (5) means to an angular spectrum of plane waves generated by the medium in response to the output of the spatial modulator, phase encoder, and first Fourier lens.

Abstract: A pattern recognition apparatus and a method for operating same. The apparatus includes a volume holographic medium (4) having a plurality of Fourier-space volume holograms representing pattern templates stored within. The apparatus further includes a spatial light modulator (1) and a phase encoder (2). The phase encoder has an output optically coupled to the medium by a first Fourier transform lens (3). The spatial light modulator spatially modulates a spatially uniform laser beam (7) in accordance with an unknown pattern. The two-dimensional phase encoder causes the spatially modulated laser beam to be spatially distributed prior to application to the medium. The apparatus further includes a detector (6, 11) having an input optically coupled by a second Fourier transform lens (5) means to an angular spectrum of plane waves generated by the medium in response to the output of the spatial modulator, phase encoder, and first Fourier lens.

Abstract: An all-optical, continuous-time, recurrent neural network is disclosed which is capable of executing a broad class of energy-minimizing neural net algorithms. The network is a resonator which contains a saturable, two-beam amplifier; two volume holograms; and a linear, two-beam amplifier. The saturable amplifier permits, through the use of a spatially patterned signal beam, the realization of a two-dimensional optical neuron array; the two volume holograms provide adaptive, global network interconnectivity; and the linear amplifier supplies sufficient resonator gain to permit convergent operation of the network.

Abstract: An all-optical, continuous-time, recurrent neural network is disclosed which is capable of executing a broad class of energy-minimizing neural net algorithms. The network is a resonator which contains a saturable, two-beam amplifier; two volume holograms; and a linear, two-beam amplifier. The saturable amplifier permits, through the use of a spatially patterned signal beam, the realization of a two-dimensional optical neuron array; the two volume holograms provide adaptive, global network interconnectivity; and the linear amplifier supplies sufficient resonator gain to permit convergent operation of the network.

Abstract: A tunable, integrated WDM optic couler for coupling optical energy to and from channel waveguides in response to the application of Surface Acoustic Waves (SAW's ), and a distributed processor computer control system utilizing the couplers. A first range of SAW's is used to couple optical energy of selected wavelengths from a channel waveguide driven by a LED to multiplex optical energy to a common optic loop and a second, non-overlapping range of SAW's is used to couple optical energy from the loop to a second channel waveguide. The second, receiving channel waveguide includes a Bragg deflector, planar waveguide and photodetector arrays to demultiplex the optical energy by focusing selected wavelengths of optical energy on selected portions of the photodetector arrays. Changes in the acoustic wavelengths and amplitudes permit tuning of the coupler and computer system by altering the portion and wavelengths, respectively, of optical energy coupled by each section of each coupler.

Abstract: An integrated optical waveguide structure which provides for efficient, single-mode propagation of light across an interface between two contiguous waveguide layers of differing effective refractive index. The waveguides are formed by layers of increased index of refraction formed at the surface of a substrate and serve to support propagation of optical electromagnetic radiation along the surface of the substrate. A refractive interface is provided at the interface of two such surface layers supporting modes of differing effective indexes of refraction. By underlying one of the surface layers with an additional layer having a particular, but different, index of refraction, a single mode of propagation is supported throughout both of the surface waveguides. General applications in the formation of optical waveguide components as well as a more extensive treatment with the formation of a lens is also disclosed using proton exchange in crystalline LiNbO.sub.3.

Abstract: Described herein is an integrated acousto-optic circuit for analyzing the spectrum of a radar signal. A waveguided optical beam is first split into two parts, one of which interacts with a surface acoustic wave generated by a reference signal and the second of which interacts with a surface acoustic wave generated by the signal to be analyzed. The two resulting phase-modulated optical waves then are recombined, Fourier transformed by a lens and finally caused to impinge on an array of photodetectors. The array of detectors is arranged so that each element of the array responds to the combination of one component of the time-varying signal to be analyzed and one component of the time-varying reference signal, that response being an output signal at some preselected radio frequency which is proportional to the amplitude of the frequency component of the radar signal to be analyzed. The several optical components are disclosed as formed on a single substrate integrated optical circuit.

Abstract: A compact lens-less spectrum analyzer where a laser impinges upon a distributed Bragg deflector via a slab-coupled optical waveguide and is bent 90 degrees. A surface acoustic wave transmitter controlled by an R-F frequency puts out a traveling strain wave which deflects the light beam according to the frequencies present; a manifold of distributed Bragg deflectors receive the deflected signal and are so arranged as to resonate at a particular frequency; the output of the resonating Bragg deflector is detected by a CCD or self-scanning diode array which produces an output indicative of the particular frequency detected.

Abstract: There is disclosed an integrated optical detector comprising a semiconductor substrate having an optical waveguide formed integrally therewith and a photodetector made from the same semiconductor material as the waveguide and integrally coupled to it. The detector region is sensitive to light of the same wavelengths that can be transmitted through the waveguide region of the semiconductor without excessive absorption therein by virtue of the fact that after the waveguide is formed proton bombardment of the detector portion thereof is used to create optically active defect centers thereby shifting the effective absorption edge in the detector region. Where gallium arsenide is used as the semiconductor defect levels induced by implantation of high energy protons give rise to optical absorption between 6 micron and 0.9 micron. This results in detector action in the presence of a Schottkey barrier depletion layer.