Transfer functions based on Bragg detuning effects for image-bearing holograms recorded in photorefractive crystals

We study detuning effects that modify the Bragg condition in photorefractive crystals and analyze the influence of these effects on the retrieval of information that is stored in such crystals. We examine and integrate several mechanisms that induce Bragg detuning, including the effects of temperature changes, applied electric fields, and polarization changes, taking into account the anisotropic nature of photorefractive crystals. Transfer functions based on these detuning effects are defined and computed to examine and quantify the signal quality that is obtained during the readout of image-bearing holograms. The different recording configurations and geometries that are typically used in photorefractive applications are considered and compared. Finally, we study more specifically the consequences of temperature-induced detuning in the context of a holographic data storage system that uses thermal fixing. We show theoretically and experimentally that distortions (in this case limited field of view) occur on readout, and we propose solutions to improve the quality of the retrieved images. (C) 1996 Optical Society of America