Realizing particle population inversion of 2.7 μm emission in heavy Er3+/Pr3+ co-doped low hydroxyl fluorotellurite glass for mid-infrared laser.

In this work, the population bottleneck of Er3+: 4I 11/2 → 4I 13/2 was overcome for the first time in heavy Er3+/Pr3+ co-doped TeO 2 –BaF 2 –La 2 O 3 –LaF 3 (TBLL) low hydroxyl fluorotellurite glasses. Infrared emission spectra and fluorescence lifetime decay curves reveal that Pr3+ ions could deplete the electrons from the Er3+: 4I 13/2 level faster than those from the Er3+: 4I 11/2 under 980 nm excitation. Specifically, the energy transfer (ET) efficiency of the Er3+: 4I 13/2 → Pr3+: 3F 3,4 process (ET1) reached 96.27%, while that of the Er3+: 4I 11/2 → Pr3+: 1G 4 process (ET2) is only 2.17% in the Er3+/Pr3+ co-doped glass. Additionally, the energy transfer mechanism of Er3+ and Pr3+ ions was investigated using the Dexter theory, where the energy transfer microscopic parameters C D-A are 13.21 × 10−40 cm6/s and 0.89 × 10−40 cm6/s for the ET1 and ET2 processes, respectively. Finally, a numerical simulations laser model was developed to discuss the laser properties of the Er3+/Pr3+ co-doped TBLL fibers. The simulation results indicate that a 2.7 μm laser with a maximum output power of 2.26 W and slope efficiency of 13.89% could be achieved when the fiber background loss is reduced to 0.5 dB/m. The above results suggest that the Er3+/Pr3+ co-doped TBLL glass has great potential applications in mid-infrared fiber lasers. [ABSTRACT FROM AUTHOR]