Use of Ga Doping to Suppress Optical Damage in Near-Stoichiometric LiNbO3Crystals

We investigated the effect of Ga doping on optical damage (photorefractive damage) in near-stoichiometric LiNbO3 (SLN) crystals. SLN crystals doped with Ga (Ga:SLN) were grown from a Li-rich solution by a top-seeded solution growth method. The optical damage resistance of the crystals was investigated at 532 nm. Crystals with a Ga doping concentration of at least 0.49 mol % showed no optical damage. The Ga doping shifted the OH- absorption peak position from 2.88 to 2.85 µm for crystals with a 0.49 mol % concentration. This concentration is lower than the 1 mol % Mg doping concentration required to suppress optical damage in SLN crystals. This attractive optical damage resistance characteristic makes Ga:SLN crystals another candidate as an optical damage resistant material, in addition to Sc-doped SLN crystals, for applications such as electrooptic devices and quasi-phase-matched frequency converters.