Holographic shift multiplexing in thin volumetric media

We describe a three-dimensional theoretical model of holographic shift multiplexing in thin volumetric media in paraxial approximation. In the case of shift multiplexing with three-dimensional beams, additional cross talk is found and its origin is attributed to Bragg-matching synchronism which occurs when shift in both transverse dimensions (x and y) is considered. The origin of this cross talk is attributed to three-dimensional Bragg degeneracy. The experimental results obtained for the case of two spherical wave front beams are in excellent agreement with the theoretical predictions. We propose theoretically that the cross talk in spherical multiplexing can be minimized if reference and signal waves have the same radius of curvature.