Effect of composition on the spontaneous emission probabilities, stimulated emission cross-sections and local environment of Tm3+ in TeO2–WO3 glass

Effect of composition on the structure, spontaneous and stimulated emission probabilities of various 1.0 mol% Tm2O3 doped (1−x)TeO2+(x)WO3 glasses were investigated using Raman spectroscopy, ultraviolet–visible–near-infrared (UV/VIS/NIR) absorption and luminescence measurements. Absorption measurements in the UV/VIS/NIR region were used to determine spontaneous emission probabilities for the 4f–4f transitions of Tm3+ ions. Six absorption bands corresponding to the absorption of the 1G4, 3F2, 3F3 and 3F4, 3H5 and 3H4 levels from the 3H6 ground level were observed. Integrated absorption cross-section of each band except that of 3H5 level was found to vary with the glass composition. Luminescence spectra of the samples were measured upon 457.9 nm excitation. Three emission bands centered at 476 nm (1G4→3H6 transition), 651 nm (1G4→3H4 transition) and 800 nm (1G4→3H5 transition) were observed. Spontaneous emission cross-sections together with the luminescence spectra measured upon 457.9 nm excitation were used to determine the stimulated emission cross-sections of these emissions. The effect of glass composition on the Judd–Ofelt parameters and therefore on the spontaneous and the stimulated emission cross-sections for the metastable levels of Tm3+ ions were discussed in detail. The effect of temperature on the stimulated emission cross-sections for the emissions observed upon 457.9 nm excitation was also discussed.