Effect of the oxidation state of LiNbO3:Fe on the diffraction efficiency of multiple holograms
We show that the oxidation state of Fe in LiNbO3 has two competing effects on the diffraction efficiency of multiple holograms in 90 degree-geometry holographic storage. For crystals with moderate absorption, the saturation space-charge field is larger after high-temperature reduction treatment. However, reduction also increases absorption, which reduces the overall diffraction efficiency. We develop a theoretical model that predicts achievable diffraction efficiency as a function of oxidation state, doping level, photovoltaic field, crystal length, and region of beam overlap. We compare this model with experimental results for achievable diffraction efficiency and erasure-time constant.
© 1996 Optical Society of America Received December 8, 1995 This research is supported by Rome Labs and the National Science Foundation Center for Neuromorphic Systems Engineering. We thank Ya-yun Liu for assistance with the high-temperature annealing.