28 April 1994 Fixing and IR response of doped barium titanate
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Abstract
Two key obstacles to the development of high-capacity three-dimensional information mass storage systems using photorefractive crystals are: (1) readout of holograms stored in the conventional manner is destructive, and (2) undoped photorefractive crystals are typically quite insensitive to red and infrared write light from diode lasers (the preferred source). As a consequence, bulky, expensive ion lasers have been necessary for hologram writing. Thus hologram fixing and high infrared sensitivity in these materials are both important if practical systems are to be built. We present our own high-temperature (80-110°C) photorefractive grating writing results for a variety of pure and doped barium titanate (BaTiO3) crystals. We found strong fixable secondary gratings that correlated with increasing levels of Fe and Ni in doped crystals. Fixing was not observed in our pure crystals or those doped with V, Rh, or Co. Fixing was enhanced in an iron-doped crystal reduced by high-temperature annealing at low oxygen partial pressures. We also found that the readout diffraction efficiency of a fixed grating in BaTiO3 is a rapidly increasing function of readout temperature above a threshold temperature, which depends upon the crystal orientation. Lower temperatures lead to longer storage times, as would be expected if the carriers forming the fixed grating have a thermally activated mobility. We also report preliminary experimental results on blue Rh-doped BaTiO3 crystals with fast and high-gain infrared (840 nm) response.
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T. W. McNamara, T. W. McNamara, S. G. Conahan, S. G. Conahan, Irina Mnushkina, Irina Mnushkina, Mark H. Garrett, Mark H. Garrett, Hans Jenssen, Hans Jenssen, Cardinal Warde, Cardinal Warde, } "Fixing and IR response of doped barium titanate", Proc. SPIE 10270, Photorefractive Materials, Effects, and Applications: A Critical Review, 1027008 (28 April 1994); doi: 10.1117/12.178630; https://doi.org/10.1117/12.178630
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