Energy transfer and 1.8 μm emission in Tm3+/Yb3+ codoped lanthanum tungsten tellurite glasses

Tm3+/Yb3+-codoped lanthanum tungsten tellurite (TWL) glasses are prepared by melt-quenching method and the thermal stability of the glasses is analyzed. To evaluate the spectroscopic properties of Tm3+ in TWL glass, the Judd–Ofelt intensity parameters (Ωtt = 2, 4, 6), radiative transition rates, radiative lifetimes, and branching ratios of Tm3+ are calculated based on the absorption spectrum. The 1.8 μm emission of the samples are investigated under the excitation of 980 nm LD. Large product of emission cross-section and lifetime (σemτR) of Tm3+: 3F4 → 3H6 is obtained, and the maximum gain coefficient at around 1835 nm is 3.6 cm−1. The energy transfer processes of Yb3+–Yb3+ and Yb3+–Tm3+ are analyzed, the results show that the Yb3+ ions can transfer their energy to Tm3+ ions with a large energy transfer coefficient, and a maximum efficiency of 89%.