Photorefractive properties of highly-doped lithium niobate crystals in thevisible and near-infrared

Light-induced refractive-index changes, bulk-photovoltaic current densities , and photoconductivities of photorefractive iron-doped lithium niobate cry stals (iron concentrations between 0.02 and 0.17 wt. %) are investigated in detail using visible and near-infrared light. It turns out that the one-ce nter model predicts the material performance correctly for small iron conce ntrations (c(Fe) < 0.06 wt. % Fe2O3), only. A strong increase of the photoc onductivity for higher doping levels limits the space-charge fields. Refrac tive-index changes up to 7 x 10(-4) for green and 2.8 x 10(-4) for near-inf rared ordinarily polarized light are obtained. The corresponding hologram m ultiplexing numbers are 11 for green and 5 for near-infrared light.