Photorefractive properties of lithium niobate crystals doped with manganese
The photorefractive properties of lithium niobate crystals doped with manganese (Mn) have been investigated. It is found that the effect of dark decay due to electron tunneling, which is the limiting factor of the highest practical doping level, is less in LiNbO3:Mn than in LiNbO3:Fe, and higher doping levels can be used in LiNbO3:Mn to achieve larger dynamic range and sensitivity for holographic applications. The highest practical doping level in LiNbO3: Mn has been found to be similar to0.5 wt.% MnCO3, and refractive-index changes and sensitivities up to 1.5 X 10(-3) and 1.3 cm/J are measured for extraordinarily polarized light of the wavelength 458 nm. It has been found that, in terms of both dynamic range (or refractive-index change) and sensitivity, the optimal oxidation state is highly oxidized. The distribution coefficient of Mn has been determined to be similar to1. Absorption measurements are used to obtain more information about charge-transport parameters. The material is excellently suited for holographic recording with blue light. The hologram quality is outstanding because holographic scattering is much weaker compared with that in, e.g., iron-doped lithium niobate. Thermal fixing has been successfully demonstrated in LiNbO3:Mn crystals. (C) 2003 Optical Society of America.