LINBO3 WITH THE DAMAGE-RESISTANT IMPURITY INDIUM

We report on a detailed investigation (EPR, SHG, optical absorption, l uminescence and Raman scattering) on the new damage-resistant impurity indium in LiNbO3, where the increased photoconductivity strongly redu ces the photorefractive effect. EPR and optical absorption measurement s point to a complete disappearance of the Nb antisite in LiNbO3:In fo r all In concentrations. We believe that the very effective driving ou t of Nb antisites by In is due to the trivalent charge state of In and the possibility of charge self-compensation. Similarities in the prop erties of Mg-, Zn- or In-doped samples are discussed. Simultaneous dop ing with In and Zn leads to an addition of both contributions, in part icular for optical frequency doubling and luminescence. Raman studies prove that In does not improve the stoichiometry of the crystals. Indi um doping provides the possibility to control simultaneously phase-mat ching conditions and to reduce drastically photorefraction. Therefore, In co-doped LiNbO3 compositions are promising materials for applicati ons after solving contemporary growth problems.