Thermal stability and optical properties of a novel Tm3+ doped fluorotellurite glass

A series of fluorotellurite glasses based on (81-x)TeO2-(10+x)KF-9La(2)O(3) (TKL), where x=0 mol.%, 5 mol.%, 10 mol.%, 15 mol.%, doped with 2000 ppm Tm2O3, were prepared by the conventional melt quenching method. The influence of KF content on the thermal stability and optical spectroscopic properties of the Tm3+ doped fluorotellurite glasses were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), density measurement, Fourier transform infrared spectroscopy (FTIR), UV-VIS-NIR optical spectroscopy and fluorescence spectroscopy. Judd-Ofelt intensity parameters of Tm3+ in as-prepared glasses were determined and used to calculate the spontaneous emission probabilities and the radiative lifetime for the 4f-4f transitions of the Tm3+ ions. Stimulated emission cross sections in the 1470 nm region (sigma(se)) were evaluated by Fuchtbau-Ladenburg formula. The results showed that KF substitution of TeO2 was beneficial to improving the thermal stability, decreasing glass density and reducing the content of OH related groups for the investigated fluorotellurite glasses. The glass with composition of 66TeO(2)-25KF-9La(2)O(3) (named TKL25) had the longest radiative lifetime of the H-3(4) (361 mu s) and the largest FWHMx sigma(se) value (420.07x10(-28) cm(3)), which made it a promising material for S-band fiber amplifiers.