Photorefraction in LiNbO3 as a function of [Li]/[Nb] and MgO concentrations

Abstract

Photorefractive damage, photoconductivities, and photogalvanic currents of LiNbO3 single crystals have been investigated as a function of [Li]/[Nb] and MgO concentrations. Near stoichiometric LiNbO3 single crystal, having large [Li]/[Nb] ratios of 0.993, shows lower photorefractive damage resistance than congruent LiNbO3. However, crystals doped with a small amount of MgO (>0.78 mol %) exhibit no measurable photorefractive damage at 532 nm to intensities of as much as 2 MW/cm2. This remarkable decrease of photorefraction that was found can be attributed to the decrease of saturated space charge field results from a combination of the increased photoconductivity and the decreased photogalvanic current of the crystal.