Optical data storage using orthogonal wavelength multiplexed volume holograms

We propose a volume holographic data storage scheme that employs counterpropagating reference and image beams and wavelength multiplexing for page differentation. This method is compared with that based on angular multiplexing. A reduction in holographic cross talk is predicted. Further cross-talk reduction that is due to sidelobe suppression is observed in experiments by using photorefractive crystals and the proposed orthogonal data storage

Self-enhanced diffraction from fixed photorefractive gratings during coherent reconstruction

We explore, theoretically and experimentally, the effects of self-enhancement (or self-depletion) of the diffraction which occurs during coherent reconstruction from fixed photorefractive gratings. These effects are caused by interference between a secondary grating, which forms between the readout and the reconstructed beams, and the fixed grating

Photorefractive Materials For Optical Computing And Image Processing

Photorefractive materials have been used as the nonlinear optical media in various optical computing and image processing applications. Devices such as passive phase conjugate mirrors, image subtractors, optical limiters and thresholders can be constructed with materials whose index of refraction is a function of light intensity. It is the purpose of this paper, then to describe some of these materials on the basis of their nonlinear optical response

Real time image subtraction and "exclusive or" operation using a self-pumped phase conjugate mirror

Real time "exclusive or" operation with an interferometer using a self-pumped phase conjugate mirror is reported. Also, results of image subtraction and intensity inversion are shown

Self-starting passive phase conjugate mirror with Ce-doped strontium barium niobate

We report the use of Ce-doped SrxBa1−xNb2O6, x=0.60 and 0.75, as the holographic four-wave mixing medium in the construction of a self-starting passive phase conjugate mirror using internal reflection. Without correcting for Fresnel reflections, a steady-state phase conjugate reflectivity of 25% was measured with Sr0.75Ba0.25Nb2O6:Ce. The distortion correcting property of such a mirror was demonstrated using an imaging experiment

Photorefractive Properties Of Undoped, Cerium-Doped, And Iron-Doped Single-Crystal Sr_(0.6)Ba_(0.4)Nb_2O_6

We present the results of our theoretical and experimental studies of the photorefractive effect in single-crystal SBN:60, SBN:Ce, and SBN:Fe. The two-beam coupling coefficients, response times, and absorption coefficients of these materials are given

Photorefractive Properties of Undoped and Doped Single Crystal SBN:60

We present the results of our theoretical and experimental studies of the photorefrac-tive effect in single crystal SBN:60, SBN:Ce, and SBN:Fe. Specifically, the two-beam coupling coefficients, response times and absorption coefficients of these materials are given

Photorefractive properties of Ce- and Ca-doped Sr0.6Ba0.4Nb2O6

We present the results of experimental study of the absorption coefficient, two-beam photorefractive coupling constant, and photorefractive response time of a doubly Ce- and Ca-doped Sr0.6Ba0.4Nb2O6. This crystal displays enhanced photorefractive response at near infrared wavelengths when compared to Ce-doped SBN:60. The temperature dependence of the coupling constant over the range from –30 to 40 °C has also been studied

Photorefractive Properties Of Ferroelectric BaTiO_3 and SBN:60

The results of theoretical and experimental studies of the photorefractive effect in two different classes of materials--perovskite BaTiO_3 and tungsten bronze SBN--have been examined. The interesting features of these measurements indicate that two-beam coupling coefficients, response times, and absorption coefficients enhanced significantly in doped crystals which appear to be suitable for future device concepts. A comparison of these materials showed that Ce-doped SBN:60 single crystals are superior to BaTiO_3 for use in photorefractive applications due to higher two-beam coupling, sensitivity, and overall flexibility of tungsten bronze crystals

Real-Time Image Processing Using A Self-Pumped Phase Conjugate Mirror

Real-time 'exclusive or' operation obtained with an interferometer using a self-pumped phase conjugate mirror is reported. Also, results of image subtraction, intensity inversion and image differentiation are shown. Methods of extending the operation to higher order differentiation and of obtaining the Laplacian are discussed