Blue and green upconversion in Er3+-doped fluoroindate glasses

Article abstract of DOI:10.1016/0038-1098(93)90669-E

The upconversion properties of Er³⁺ in fluoroindate bulk glasses (composition: 40InF₃-20ZnF₂-16BaF₂-(20-x) SrF₂-2GaF₃-2NaF-xErF₃ with x=1, 2, 3, and 4 mole %) are investigated, following ⁴F_9/2 excitation with a red krypton laser. A strong green and a weaker blue luminescence is observed at room temperature corresponding to emissions from the thermally coupled ⁴S_3/2 and ²H_11/2 bands and the ²H_9/2 level respectively. Resonant energy transfer processes involving two excited erbium ions and a two-step absorption process are proposed to explain the upconversion phenomena. The emission intensities depend on the excitation power as P_excⁿ with 1.5 ≤n≤1.7 for the green and 1.6 ≤n≤1.9 for the blue emission. The decay times and the relative intensities of the luminescences are also studied as a function of Er³⁺ concentration.