1.23 μm emission of Er/Pr-doped water-free fluorotellurite glasses.

To investigate the relatively unexplored 1.2 μm region, we identified a near-infrared emission at around 1.23 μm from Er3+/Pr3+-codoped water-free fluorotellurite glass with a composition of 60TeO2-30ZnF2-10NaF (TZNF60, mol. %). Under the condition of pumping with the 488 nm optical parametric oscillator (OPO) laser system, the directly measured lifetime (τ(f)) at 1.23 μm in Er/Pr-codoped fluorotellurite glasses is about 111.2 μs, much longer than that of Er-doped fluorotellurite glass (80.1 μs). The stimulated emission cross section (σ(em)) and quantum efficiency (η) for Er3+:4S3/2→4I11/2 transition are greatly enhanced when appropriate Pr3+ ions are incorporated. These advances arise partially from the absence of the hydroxyl (OH) group and low phonon energy with the addition of a large amount of fluorides into oxide-based host glasses. With high quantum efficiency (56.2%) and a large stimulated cross section (4.03×10(-21) cm2), Er3+/Pr3+-codoped TZNF60 glass is regarded as promising material for the development of optical amplification and laser operation at the relatively unexplored 1.2 μm region.