Effect of composition on the spontaneous emission probabilities, stimulated emission cross-sections and local environment of Tm 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.