Enhancement of 1.54 μm emission in Er:LiNbO3 crystal by codoping with Zn2+ ions

The enhanced intensity and lengthened lifetime of 1.54 μm emission were observed for Er:LiNbO3 crystal codoped with Zn2+ ions. The ZnO codoping led to the reduction of the green upconversion emission in Er:LiNbO3 crystals. The decay trace of the 4S3/2→4I15/2 was obviously nonexponential for Er:LiNbO3 codoped with 0 and 3 mol.% ZnO, but became exponential for one codoped with 6 mol.% ZnO. The OH− absorption spectra showed after codoping with Zn2+ ions, the OH− absorption peaking position shifted from ∼3495 to 3484 cm−1, and the absorption cross section decreased. These spectroscopic characteristics suggested that the improvement of 1.54 μm emission was attributed to the reduction of Er3+ cluster sites.