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.