Investigation of 2.0 μm emission in Tm3+ and Ho3+ co-doped TeO2–ZnO–Bi2O3 glasses

Tm3+ and Ho3+ co-doped TeO2–ZnO–Bi2O3 (TZB) glasses were prepared by the conventional melt-quenching method. Two micrometre emission properties of the TZB glasses exited by 808 nm Laser Diode (LD) were analyzed and discussed. The Judd–Ofelt parameters, spontaneous radiative transition probabilities and radiative lifetime of Ho3+ were calculated based on the absorption spectra by using Judd–Ofelt theory. The absorption spectra and fluorescence spectra were measured. The predicted spontaneous radiative transition rate of 5I7 → 5I8 of Ho3+ is as high as 466.8 s−1. The result of fluorescence spectra indicates that the maximum emission intensity of Ho3+ 2.0 μm and of Tm3+ 1.47 μm emission can be achieved at the concentration of 1 mol% Tm2O3 and 1 mol% Ho2O3 in TZB glasses. The maximum absorption and emission cross-section of Ho3+ near 2.0 μm are 0.87 × 10−20 cm2 at 1951 nm and 1.07 × 10−20 cm2 at 2047 nm, respectively.