Luminescent Enhancement in Mg- and Er-Codoped LiNbO₃ Crystals

We investigate the MgO codoping-induced effect on the luminescent properties of Er³⁺-doped and Er/Mg codoped LiNbO₃ crystals. The emission and excitation spectra and the absorption spectra are measured. The results show that the luminescent behaviour of Er³⁺ ions is very sensitive to the codoping of Mg²⁺ ions. According to the photorefractive level theory, we propose a quench model for the Er/Mg codoped lithium niobate crystal. The quench centres are suggested to be the bipolaron (Nb_Li-Nb_Nb), we attribute the luminescent enhancement to the decreasing concentration of these centres. The luminescent enhancement effect is successfully explained.