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Erasure characteristics of off-Bragg readout during nonvolatile holographic storage in doubly doped LiNbO3 crystals

In this paper the erasure characteristics with different readout conditions, especially off-Bragg readout, during nonvolatile holographic storage in doubly doped LiNbO3 crystals are investigated. The results show that off-Bragg readout by red beam can achieve modest diffraction efficiency while self-enhancement readout gets highest and self-depletion readout has lest diffraction efficiency. During erasing phase, the fast erasure case is that off-Bragg red beam and ultraviolet light are simultaneously used for illumination. It is indicated that the greatest effect on the erasure of the former recorded gratings during multiplexing holograms is the recording of the others gratings, and new recording schedule during multiplexing technique should be considered according to off-Bragg erasing. The experimental results are well verified by theoretical simulation basing on two-center material equations and two beam coupling equations.