Abstract

The ultraviolet-visible and infrared absorption spectra of Fe₂O₃ and MgO co-doped lithium niobate (LiNbO₃) crystals have been investigated. The experimental results show that some Fe²⁺ ions are still in Li-sites while the doping concentration of MgO is above threshold. Our results show that the large reduction of defect (${\text{Mg}}_{\text{Li}}^{+}-{\text{V}}_{\text{Li}}^{-}$) in nearly stoichiometric LiNbOs is the key factor to reduce the content of $({\text{Fe}}_{\text{Li}}^{+}-{\text{V}}_{\text{Li}}^{-})$ for anti-photorefraction. Based on defect chemical analysis, we obtained that only 1.3 mol.% of MgO is needed to suppress the optical damage completely in a nearly stoichiometric LiNbO₃ crystal with [Li]/[Nb]=49.9/50.1 while 21.2 mol.% needed in congruent ones.

© 2001 Optical Society of America