2.0 μm emission properties and energy transfer processes of Yb3+/Ho3+ codoped germanate glass

Ho3+ doped germanate glass sensitized by Yb3+ has been investigated for potential application as a near-infrared laser material. The characteristic temperatures are determined by differential scanning calorimeter, and the absorption and emission spectra are measured. According to absorption spectra, Judd-Ofelt parameters and radiative transition probabilities are calculated and analyzed by Judd-Ofelt theory. The intensity of emission spectra shows a strong dependence upon the Yb3+ concentration. The result also indicates that Yb3+ plays an important role in the emission of 2.0 mu m by transferring the 980 nm excitation energy to Ho3+. The energy transfer process from Yb3+ to Ho3+ is analyzed and the result shows that coefficient of the forward energy transfer Yb3+ -> Ho3+ is 19 times of magnitude larger than that of the backward energy transfer Yb3+ <- HO3+. It is found that the highest gain in 2.0 mu m region could be achieved from the germanate glass with 5.0 mol % Yb2O3 and 1.0 mol % Ho2O3. The present Yb3+/Ho3+ codoped germanate glass with high emission cross section of Ho3+:I-5(7) -> I-5(8) at 2.0 mu m and efficient energy transfer from Yb3+ to Ho3+ will be a suitable material for developing solid state lasers around 2.0 mu m. (C) 2010 American Institute of Physics. [doi:10.1063/1.3468726]