Doping mechanism of optical-damage-resistant ions in lithium niobate crystals

The doping mechanism of optical-damage-resistant ions (Mg2+, Zn2+, In3+, Sc3+, Hf4+, and Zr4+) in the lithium niobate crystallographic frame is quantitatively studied from the chemical bond viewpoint. Calculated results show that optical-damage-resistant ions have a strong interaction with the lithium niobate matrix, which is quantitatively evaluated by the deviation between normal and calculated valence states and the global instability index. All optical-damage-resistant ions first substitute NbLi and then Li ions, they change their dopant occupancies from Li to Nb sites at the same global instability index value 0.1055. On the basis of such a quantitative interaction, the doping mechanism of these ions is finally derived. Furthermore, a criterion in searching for new optical-damage-resistant ions is also proposed.