Effect of composition on the spontaneous emission probabilities, stimulated emission cross-sections and local environment of Tm 3+ in TeO 2–WO 3 glass

Abstract

Effect of composition on the structure, spontaneous and stimulated emission probabilities of various 1.0 mol% Tm 2O 3 doped (1− x)TeO 2+( x)WO 3 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 Tm 3+ ions. Six absorption bands corresponding to the absorption of the 1G 4, 3F 2, 3F 3 and 3F 4, 3H 5 and 3H 4 levels from the 3H 6 ground level were observed. Integrated absorption cross-section of each band except that of 3H 5 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 ( 1G 4→ 3H 6 transition), 651 nm ( 1G 4→ 3H 4 transition) and 800 nm ( 1G 4→ 3H 5 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 Tm 3+ 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.