Study on the photorefractive properties of Sc, in co-doped lithium niobate crystals

The Sc:In:LiNbO3 crystals co-doped with 0.5 mol% Sc2O3 and 0, 0.5, 0.75 and I mol% In2O3 were grown by the Czochralski method. The structure of the crystals was measured by infrared spectra. The mechanism of the shift of OH- absorption peak was investigated. The photo-damage resistance ability of Sc:In:LiNbO3 crystals was observed by the straightly observing transmission facula distortion method. The Sc:In:LiNbO3 waveguide substrates were fabricated by the proton exchange technique using benzoic acid as the proton source. The photo-damage thresholds of these y-cut waveguide substrates were measured by the m-line method. The results measured by the two methods above all show that the photo-damage resistance ability of Sc:In:LiNbO3 crystals increases two orders of magnitude in comparison with that of pure LiNbO3 crystals. The mechanism of the enhancement of the photo-damage resistance ability of Sc:In:LiNbO3 crystals is discussed by Li-vacancy model.