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A quantitative analysis of the steady-state photorefractive index perturbations caused by a given optical irradiance distribution in a periodically poled ferroelectric is presented. Axially invariant index perturbations that are due to the photogalvanic effect are reduced compared with those in a homogeneously poled crystal by approximately the square of the product of the poling-grating wave vector (K(g)) and a characteristic transverse dimension of the irradiance. This result is consistent with empirical observations in periodically poled LiNbO(3) of much higher resistance to photorefractive damage.

We report the observation of planar Y-junction waveguide splitters that are due to the bulk photovoltaic effect. The junctions are generated by multiple dark-soliton propagation in LiNbO(3) by use of low power levels (20 mW) and average intensities of 10 W/cm(2) at 488 nm. The junctions persist in the dark and can be used to divide input beams of less photorefractive sensitivity. We describe some possibilities for generating other waveguide structures in bulk and thin-film media.

We describe a novel method for the recall of linear combinations of stored data pages in a volume holographic memory based on phase-code multiplexing. Recall is demonstrated by use of a compound phase-and-amplitude spatial light modulator in the reference beam path.

We examine the consequences of permanent phase distortions on the replay of transmission volume holograms with a phase-conjugated reference wave. In the absence of Bragg degeneracies and significant Bragg mismatch, for negligible dispersion in the spatial frequency response and for negligible variation in obliquity, phase-conjugated reference waves compensate for the effects of phase distortions and permit cross-talk-free multiplexing by using orthogonal reference waves. Spatial frequency dispersion, however, is a source of image distortion and cross talk.

We report what we believe to be the first observation of photorefractive gratings in lead barium niobate (Pb(1-x)Ba (x)Nb(2)O( 6) ; PBN). A diffraction efficiency of 9% and a beam-coupling coefficient of 9 cm(-1) are obtained. After thermal fixing a grating of 0.5% is revealed at room temperature. We can improve this diffraction efficiency by optimizing fixing temperature, timing, and material parameters.

We present a novel digital holographic data storage system based on wavelength multiplexing in 90 degrees geometry, using an automated tunable diode laser and a lithium niobate crystal. The automatic storage and retrieval of a 60-kbyte data file, as well as the limitations and future implementations of the system, are discussed.

We describe a digital holographic data storage system that uses in situ thermal fixing to achieve nonvolatile readout. The system was used to store and fix 530 holograms representing 1.7 MB of digital data. The system demonstrates that fixing by heating after recording gives adequate performance for multiplex holography in the perpendicular recording geometry. The postrecording heating procedure is preferred over high-temperature recording in the perpendicular geometry to achieve Bragg matching for the entire signal angular bandwidth.

We introduce the concept of traveling grating envelopes to study the erasure dynamics in bulk photorefractive media. This new technique provides considerable physical insight into the observed photorefractive transients. We propose and demonstrate experimentally, in a Ce-doped SBN:60 crystal, two novel ways of extending the grating lifetime by trapping the grating envelope inside the medium. The incident beam ratio and the readout geometry have the largest effect on how long the grating can be read out.

Growth-induced striations in photorefractive media scatter transmitted light, degrading their performance in holographic applications. We model this phenomenon by considering the striations to be a permanent hologram within a medium and compare it with experimental results in a striated strontium barium niobate crystal. We show that the construction of the phase-conjugate signal beam by a phase conjugate of the transmitted reference beam alleviates the effects of distortions that are due to striations.