Furi Ling

Nonvolatile two-color photorefractive holographic recording in In:Ce:Cu:LiNbO3

Summary In this paper we report experimental studies of nonvolatilephotorefractive holographic recording in doping In(3mol%), which exceed the so-called threshold, in Ce:Cu:LiNbO3 crystals. The In:Ce:Cu:LiNbO3 crystal was grown by the Czochralski method and oxidized. The OH− absorption band of In:Ce:Cu:LiNbO3 crystal is 3507cm−1. The nonvolatile holographic recording in In:Ce:Cu:LiNbO3crystal is realized by two-photon fixed method. From the experiment, we found that the recording time of In:Ce:Cu:LiNbO3 crystal is lower than that of Ce:Cu:LiNbO3 crystal and there are a little lose of nonvolatile diffraction efficiencies between In:Ce:Cu:LiNbO3 and Ce:Cu:LiNbO3 crystals. In this paper, the mechanism of OH− absorption band shifting and two-photon fixed was discussed, too.

Influence of post-growth treatment on the holographic storage properties of In:Fe:LiNbO3

Summary The congruent In (3 mol%):Fe (0.03 wt%): LiNbO3 crystal has been grown by Czochralski method in air. Some crystal samples were reduced in Li2CO3 powder, and others were oxidized in Nb2O5 powder. The defects and ions location in crystal were investigated by infrared (IR) transmission spectrum. The photorefractive properties were measured by two-wave coupling and light-induced scattering resistance experiments. In the oxidized sample, the photovoltaic effect was the dominant process during recording. However, for the as-grown sample as well as the reduced, the photorefractive effect was governed by the diffuse field and the photovoltaic field, together. In addition, the reduction treatment made the photoconductivity increase, which resulted in shorter erasure time and lower diffraction efficiency, but higher light-induced scattering resistance ability. The oxidation treatment caused the inverse effect.

Nonvolatile holographic storage in LiNbO3:Mn:Ce:Cu crystal

Photorefractive lithium niobate (LiNbO3) is a promising recording medium for holographic data storage. In order to get non-volatile holograms, two-color or photo-gated holography that employs an independent pulsed or cw beam as a gating beam has been proposed to solved this problem. However from the reference we could find that the dynamic range M/# of two-color holography is lower. In this paper, triply doped Lithium niobate LiNbO3:Mn:Ce:Cu crystals and doubly doped Lithium niobate LiNbO3:Ce:Cu crystals were grown and the nonvolatile characteristic were investigated at different oxidation/reduction state and persistent holograms were recorded in these crystals. From the results, we found that the range of dynamic range M/# in a triply doped crystal is lager than that of doubly doped one. We also showed the effect of the oxidation/reduction state of the crystal on recording and readout responses. The experimental results show that there is an optimum oxidation/reduction state which resulting in the best dynamic range M/#.