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

This paper reports 2.0 mu m 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 mu m emission intensity attributed to the I-5(7)-> I-5(8) 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 pm are 7.0 x 10(-21) cm(2) at 1950 nm and 8.8 x 10(-21) cm(2) at 2048 nm, respectively. The calculated radiative lifetime of 4.4 ms for I-5(7)-> I-5(8) 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 mu m laser. (C) 2009 Elsevier B.V. All rights reserved.