LINBO3 WITH THE DAMAGE-RESISTANT IMPURITY INDIUM

We report on a detailed investigation (EPR, SHG, optical absorption, luminescence and Raman scattering) on the new damage-resistant impurity indium in LiNbO3, where the increased photoconductivity strongly reduces the photorefractive effect. EPR and optical absorption measurements point to a complete disappearance of the Nb antisite in LiNbO3:In for all In concentrations. We believe that the very effective driving out of Nb antisites by In is due to the trivalent charge state of In and the possibility of charge self-compensation. Similarities in the properties of Mg-, Zn- or In-doped samples are discussed. Simultaneous doping with In and Zn leads to an addition of both contributions, in particular for optical frequency doubling and luminescence. Raman studies prove that In does not improve the stoichiometry of the crystals. Indium doping provides the possibility to control simultaneously phase-matching conditions and to reduce drastically photorefraction. Therefore, In co-doped LiNbO3 compositions are promising materials for applications after solving contemporary growth problems.