General Introduction to Photorefraction in LiNbO3
The photorefractive properties of LiNbO3 with an emphasis on the contributions from intrinsic defects are examined. After a short background of the photorefraction with the presentation of basic relations, the photoinduced charge transport in photorefractive compositions, mainly in LiNbO3:Fe are discussed. The current concept of the dark conductivity is formulated assuming a concurrence between protons and the electronic conductivity dictated by the Fe concentration. The traditional one-center charge transport scheme based on the electron transfer between the donor Fe2+ and the deep trap Fe3+ is refreshed and the experimental data not fitting this model are listed. A refined two-center scheme based on the assumption of the Nb antisite involvement in the charge transport as a shallow electron trap is discussed and the experimental arguments supporting this model are summarized.
KeywordsCharge Transport Dark Conductivity Hologram Recording Recording Beam Dark Decay
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