INFLUENCE OF ZINC DOPING ON THE PHOTOREFRACTIVE PROPERTIES OF LITHIUM-NIOBATE

The photorefractive properties of lithium niobate crystals containing zinc dopants as well as iron ions are studied to obtain quantitative i nformation on the influence of Zn. Elementary holographic gratings are recorded and erased using light intensities from 10(2) to about 10(11 ) W/m(2). The experiments indicate that nonlinear contributions to the bulk photovoltaic effect and to the photoconductivity as well as ligh t-induced absorption changes at high intensities can be diminished by Zn doping. Additionally, Zn dopants considerably increase the photocon ductivity and thus reduce light-induced refractive index changes. Resu lts are discussed using a two-center charge transport model recently p roposed to describe the photorefractive properties of LiNbO3:Fe at hig h light intensities.