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

Abstract A series of fluorotellurite glasses based on (81– x )TeO 2 -(10+ x )KF-9La 2 O 3 (TKL), where x =0 mol.%, 5 mol.%, 10 mol.%, 15 mol.%, doped with 2000 ppm Tm 2 O 3 , were prepared by the conventional melt quenching method. The influence of KF content on the thermal stability and optical spectroscopic properties of the Tm 3+ 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 Tm 3+ 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 Tm 3+ ions. Stimulated emission cross sections in the 1470 nm region ( σ se ) were evaluated by Fuchtbauer-Ladenburg formula. The results showed that KF substitution of TeO 2 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 3 H 4 (361 μs) and the largest FWHM× σ se value (420.07×10 −28 cm 3 ), which made it a promising material for S-band fiber amplifiers.