Efficient enhanced 1.54 μm emission in Er/Yb: LiNbO3 crystal codoped with Mg2+ ions

Abstract Single crystals of Er: LiNbO3 and Er/Yb: LiNbO3 co-doped with and without Mg2+ ion were successfully prepared. The quality of the as-grown crystals were characterized. Yb3+ was demonstrated to increase an absorption efficiency at the range of 900-1000 nm. The use of Mg2+ codoping for enhancement of the Er3+:4I13/2 → 4I15/2 1.54 μ m emissions were investigated. It was found that Mg2+ ion greatly increased Er3+ 1.54 μ m emission by increasing nonradiative relaxation rate of 4I11/2 → 4I13/2 transition of Er3+ ion in Mg/Er/Yb: LiNbO3 crystal. The Mg2+ codoping also resulted in lengthening the lifetime of the 4I13/2 multiplet by 9% for the Mg/Yb/Er: LiNbO3 crystal when compared with the Yb/Er: LiNbO3 crystal. The nonradiative relaxation rate of 4I11/2 → 4I13/2 transition of Er3+ ion increases from 935 s-1 in Er/Yb: LiNbO3 crystal to 1040 s-1 in Mg/Er/Yb: LiNbO3 crystal. It was also found that the intensity of maximum phonon energy of Er: LiNbO3 at 872 cm-1 significantly strengthen by introducing the Mg2+ ion, leading to a more favourable condition for the nonradiative relaxation of 4I11/2 → 4I13/2 transition in Er3+ ion. We propose that the Mg/Er/Yb: LiNbO3 crystal may be a promising material for 1.54 μ m laser applications.