Volume holographic storage in near-stoichiometric LiNbO3 : Ce,Mn

Near-stoichiometric LiNbO3:Ce,Mn exhibited a reversible photochromic effect at room temperature. Irradiation with ultraviolet (UV) light enhanced a vi sible absorption band, and the photorefractive sensitivity to 532 nm-green recording light was greatly improved after UV irradiation. Hologram multipl exing was performed with a continuous-wave 532 nm-green laser by the angle- multiplexing method without and with UV pre-exposure. An M/# of similar to5 was obtained in a crystal of 2.55 mm-thickness in the absence of UV pre-ex posure. In multiplexing after UV pre-exposure, however, the variable sensit ivity and erasure-time constant made it very difficult to achieve a multipl e hologram storage with nearly equivalent diffraction efficiency.