Broadband 2 µm fluorescence and energy transfer process in Tm3+ doped germanosilicate glass

Glass with the composition of SiO2-GeO2-CaCO3-Li2CO3-Nb2O5-BaO-Tm2O3 has been prepared and its characteristic temperatures have been measured. ΔT (155 °C) of the glass indicates it has good thermal stability. A broadband emission spectrum around 2 µm with full-width at half-maximum close to 237 nm has been obtained, which suggests this germanosilicate glass is a competitive candidate for the ultrashort pulse generation as few broadband emission realized by Tm3+ single-doping. The calculated maximum of absorption cross section and emission cross section of the transition Tm3+:3F4→3H6 was 3.31×10−21 cm2 at 1654 nm and 6.88×10−21 cm2 at 1870 nm, respectively. Besides, the energy transfer mechanism of 2 µm fluorescence behaviors was analyzed theoretically and quantitatively. The energy transfer coefficient CD-A of cross relaxation process of Tm3+ ions was 10.9×10−40 cm6/s in SGT glass. These results indicate that the prepared glass may have promising application in 2 µm fluorescence.