OH-absorption properties of the optical damage region in codoped In/Mg:LiNbO3 crystals with various Li/Nb ratios

Abstract OH-absorption properties of the optical damage region in a series of codoped In/Mg:LiNbO 3 crystals with various Li/Nb ratios have been investigated. The OH − -associated vibrational peak at 3507 cm −1 is confirmed to occur in crystals with Li/Nb ratio of 0.94. For codoped In/Mg:LiNbO 3 crystals with Li/Nb ratio of 1.05 and 1.20, the OH − -associated vibrational peaks are detected at 3536 and 3507 cm −1 as well. A new peak at 3518 cm −1 attributed to a (In Nb ) 2− –OH − –(Mg Nb ) 3− defect center is revealed in crystals with Li/Nb ratio 1.38. When the “In–Mg threshold” concentration is reached, the optical damage resistance ability of codoped In/Mg:LiNbO 3 crystals is greatly improved.