We propose a novel random phase-coded multiplexing for encrypting holographic memory in a photorefractive LiNbO_3:Fe crystal. A rotating and shifting circular holographic diffuser is placed as a random-phase modulator in the reference beam to provide a simple yet effective method of increasing the holographic memory capabilities of the crystal. Experiments show that the angular selectivity of the rotational multiplexing experienced produces a significant increase when a larger holographic diffuser scattering angle is implemented. The proposed multiplexing scheme can also be combined with angular multiplexing to produce angular-rotational random phase-coded multiplexing, offering not only further memory possibilities but data encryption capabilities as well.
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