Study on 1.19 and 1.36 µm fluorescence for Ho-doped water-free fluorotellurite glasses

To find more efficient materials for optical amplifiers, near-infrared spectroscopic properties of Ho3+-doped water-free fluorotellurite glasses 60TeO2–30ZnF2–10NaF (mol%, TZNF60) were investigated. Excited by an OPO laser system at 534 nm, intense 1.19 (Ho3+: 5I6→5I8) and 1.36 µm (Ho3+: (5S2,5F4)→5I5) emissions in Ho3+ doped TZNF60 glasses were observed, and long directly measured lifetime at 1.19 µm is of 750–950 µs and of 32–44 µs for 1.36 µm, respectively, resulting from the absence of OH groups and the low phonon energy with the addition fluorides into tellurite oxide glasses. Among all the made Ho-TZNF60 samples, 1.00Ho2O3-TZNF60 glass presents the strongest fluorescence with larger emission cross-sections of (0.63, 0.22)×10–20 cm2 at 1.2 and 1.36 µm, respectively. Therefore, it is regarded as a promising material for the development of optical amplification and laser operation at the relatively unexplored 1.2 and 1.36 µm regions. © 2013 Elsevier B.V. All rights reserved.