Broadband 1.20 μm emission in Tm 3+-doped and Tm 3+/Tb 3+, Eu 3+ codoped gallogermanate glasses

摘要

Broadband 1.20 μm emission originating from the Thulium (Tm 3+): 1G 4 → 3H 4 transition was observed in Tm 3+-doped gallogermanate glasses under 476.5 nm excitation. The stimulated emission cross-section is calculated to be 2.85 × 10 -21 cm 2 using the Füchtbauer-Ladenburg approach. Difficulty in the population inversion between the upper 1G 4 and lower 3H 4 levels resulting from the cross relaxation process Tm 3+ [ 1G 4, 3H 6] → [ 3H 4, 3H 5] was overcome by the incorporation of Terbium (Tb 3+) and Europium (Eu 3+) ions. A Judd-Ofelt analysis was performed based on the absorption spectrum and the derived intensity parameters (Ω 2 = 4.65 × 10 -20, Ω 4 = 1.51 × 10 -20, and Ω 6 = 1.42 × 10 -20 cm 2) reveal a strong asymmetry and covalent environment between Tm 3+ ions and ligands in the host matrix. The results indicate that the Tm 3+/Tb 3+, Eu 3+ codoping scheme is promising in the development of amplifiers and lasers operating at the relatively unexplored 1.2 μm wavelength region.