Spectral Luminescent Properties of Fluoroaluminate Glasses with a Low Phosphate Content Activated by Thulium Ions and a Thulium/Ytterbium Pair

The paper presents the results of a study into the physicochemical and spectral-luminescent properties of fluorophosphate glasses doped with thulium ions and a thulium/ytterbium pair. The DSC analysis performed showed that an increase in the concentration of rare earth ions leads to an increase in the crystallization stability of glasses. The measurement and analysis of luminescence spectra in the infrared region of the spectrum, as well as the study of energy transfer from ytterbium ions to thulium ions, showed that an increase in the concentration of thulium ions leads to efficient population of the upper laser level due to the cross-relaxation process. When glass is activated with a thulium/ytterbium pair, efficient energy transfer from ytterbium ions to thulium ions is observed at thulium fluoride concentrations above 0.5 mol %, which also leads to population of the upper laser level and an increase in the luminescence intensity in the wavelength range of 1700–1800 nm.