Optical transitions of Er3+/Yb3+ codoped TeO2–WO3–Bi2O3 glass

Optical absorption and emission properties of the Er3+/Yb3+ codoped TeO2–WO3–Bi2O3 (TWB) glass has been investigated. The transition probabilities, excited state lifetimes, and the branching ratios have been predicted for Er3+ based on the Judd–Ofelt theory. The broad 1.5 μm fluorescence was observed under 970 nm excitation, and its full width at half maximum (FWHM) is 77 nm. The emission cross-section is calculated using the McCumber theory, and the peak emission cross-section is 1.03×10−21 cm2 at 1.531 μm. This value is much larger than those of the silicate and phosphate glasses. Efficient green and weak red upconversion luminescence from Er3+ centers in the glass sample was observed at room temperature, and the upconversion excitation processes have been analyzed.