Upconversion mechanisms in Tm3+ doped lead fluoroindogallate glasses

A spectroscopic study of Tm3+ doped lead fluoroindogallate was performed here. The samples were prepared by fusion in a dry box under a nitrogen atmosphere. Their compositions are 30PbF2–20GaF3–15InF3–15ZnF2–(20 − x)CaF2–xTmF3 (with x=0.1, 0.25, 0.5, 1.0, 2.0 and 3.0 mol%). Pumping with 660 or 649 nm resulted in three upconverted emissions at 360 nm (1D2 → 3H6), 450 nm (1D2 → 3F4) and 470 nm (1G4 → 3H6). The relative intensity between the 470-nm emission and the others increased as the Tm3+ concentration increases. The observed features were satisfactorily explained by cross-relaxation mechanisms involved in the population of the 1D2, 1G4 and 3F4 levels.