~2 μm emission properties and energy transfer processes in Tm3+ doped Bi2O3-GeO2-Na2O glass laser material

Tm 3+ doped Bi 2 O 3 -GeO 2 -Na 2 O glass samples were synthesized by conventional melt-quenching method. The Raman spectra measurements showed the maximum phonon energy of prepared glass is 794 cm −1 , which is considerably lower than silicate glasses . Based on the measured absorption spectra , Judd-Ofelt intensity parameters, spontaneous radiative transition probabilities and radiative lifetimes were calculated to elucidate the radiative properties of Tm 3+ in the presented glass. Intense near infrared emission around ~2 μm was obtained under the pump of 808 nm laser diode . A large stimulated emission cross section (5.51 × 10 −21  cm 2  at 1851 nm) of Tm 3+ : 3 F 4 → 3 H 6 was achieved in the prepared bismuth germanate glass doped with 1 mol% Tm 2 O 3 . Besides, the energy transfer processes among Tm 3+ were analyzed using the extended overlap integral method. These results indicate that the presented glass is a promising candidate for ~2 μm laser applications.