Defect structure and optical damage resistance of In:Mg:Fe:LiNbO3 crystals with various Li/Nb ratios

Abstract In:Mg:Fe:LiNbO 3 crystals were grown by the Czochralski technique with various ratios of Li/Nb=0.85, 0.94, 1.05, 1.20 and 1.38 in the melt. The crystal composition and defect structure were analyzed by the UV–vis and IR spectroscopy. A new narrow OH − -associated vibrational peak at 3518 cm −1 was revealed in In:Mg:Fe:LiNbO 3 crystals with the ratio of Li/Nb=1.38. It was attributed to a (In Nb ) 2− –OH − –(Mg Nb ) 3− defect center. The optical damage resistance of In:Mg:Fe:LiNbO 3 crystals was studied by the transmitted beam pattern distortion method. The results show that when both the In 2 O 3 threshold and the “In–Mg threshold” concentrations are reached, as for the Li/Nb ratio of 1.38, the optical damage resistance of In:Mg:Fe:LiNbO 3 crystals is the highest.