Enhanced 2.75 µm emissions of Er3+ via Eu3+ deactivation in PbF2 crystal

Abstract

Abstract The use of Eu3+ codoped for the enhancement of the transition of Er3+: 4I11/2→4I13/2 ~2.75 µm emissions was observed in the Er/Eu co-doped PbF2 crystal for the first time. The ~2.75 µm energy transfer mechanism and fluorescence emission properties of the Eu/Er co-doped PbF2 crystal were investigated at length. The results show that the codoped of Eu3+ ion in Er/Eu: PbF2 crystal greatly enhances Er3+:2.75 µm emission under excitation of a common 970 nm laser diode. In addition, it is found that the Eu3+ ion depopulates the lower laser level of Er3+:4I13/2, and has little effect on the upper laser level of Er3+:4I11/2 at the same time. Moreover, the energy transfer efficiency from the Er3+:4I13/2 level to the Eu3+:7F6 level is as high as 88.07%, indicating that the Eu3+ ion is an effective deactivation ion for enhancing the ~2.75 µm emission in Er/Eu: PbF2 crystal. These advantageous spectroscopic characteristics suggest that the Er/Eu: PbF2 crystal may be a promising material for ~2.75 µm mid-infrared lasers under the pump of a conventional 970 nm LD.