Optical and spectroscopic characterization of Er³⁺-Yb ³⁺co-doped tellurite glasses and fibers

Optical and spectroscopic properties of Er³⁺-Yb³⁺ co-doped TeO₂-WO₃-Nb₂O₅-Na ₂O-Al₂O₃ glasses and fibers were investigated. Emission spectra and fluorescence lifetimes of ⁴I_13/2 level of Er³⁺ion as a function of rare earth concentration and fiber length were measured in glasses. Results show that the self-absorption effect broadens the spectral bandwidth of ⁴I_13/2→ ⁴I_15/2 transition and lengthens the lifetime significantly from 3.5 to 4.6 ms. Fibers were fabricated by the rod-in-tube technique using a Heathway drawing tower. The emission power of these Er³⁺-Yb ³⁺ co-doped Step Index Tellurite Fibers (SITFs; lengths varying from 2 to 60 cm) were generated by a 980 nm diode laser pump and then the emission power spectra were acquired with an OSA. The maximum emission power spectra, within the 1530-1560 nm region, were observed for fiber lengths ranging from 3 to 6 cm. The highest bandwidth obtained was 108 nm for 8 cm fiber length around 1.53 μm.