Investigation of 2.0 μm emission in Tm3+ and Ho3+ co-doped oxyfluoride tellurite glass

This paper reports 2.0 μm emission properties of Tm3+/Ho3+ co-doped oxyfluoride tellurite glass exited by 808 nm laser diode (LD). Mid-infrared transmittance property of glass was investigated by Fourier transform infrared (FTIR) spectrometer. The real chemical composition of investigated glass was identified by X-ray photoelectric spectroscopy (XPS). Thermal stability of the glass was determined by differential thermal analysis (DTA) measurement. The Judd-Ofelt parameters, spontaneous radiative transition probabilities, branching ratios and radiative lifetime of Ho3+ were calculated based on the absorption spectra by using Judd-Ofelt theory. Results indicate that the maximum 2.0 μm emission intensity attributed to the 5I7→5I8 transition of Ho3+ was achieved at 1.5 mol% Tm2O3 and 1 mol% Ho2O3 concentrations in oxyfluoride tellurite glass. OH− absorption at 3000 cm−1 was greatly depressed by introduction of 10 mol% F−. The maximum absorption and stimulated emission cross-section of Ho3+ near 2.0 μm are 7.0×10−21 cm2 at 1950 nm and 8.8×10−21 cm2 at 2048 nm, respectively. The calculated radiative lifetime of 4.4 ms for 5I7→5I8 transition and large stimulated emission cross-section of the Tm3+/Ho3+ co-doped oxyfluoride tellurite glass indicate that the glass has a potential application in efficient 2.0 μm laser.