Optical transitions and visible upconversion in Er3+ doped niobic tellurite glass

Er3+ doped Nb2O5-TeO2 (NT) glass suitable for developing optical fiber laser and amplifier has been fabricated and characterized. Intense and broad 1.53 mum infrared fluorescence and visible upconversion luminescence were observed under 975 nm diode laser and 798 nm laser excitation. For 1.53 mum emission band, the full width at half-maximum is 51 nm, the fluorescence lifetime is 2.6 ms, and the quantum efficiency is similar to100%. The maximum emission cross section is 8.52 x 10(-21) cm(2) at 1.532 mum, and is higher than the values in silicon and phosphate glasses. Under 798 nm excitation, efficient 531, 553, and 670 nm upconversion emissions are due to two-photon absorption processes. The "standardized'' efficiency for the green upconversion light is 9.5 x 10(-4), and this value is comparable to that reported for Er3+/Yb3+ codoped fluoride glasses. Intense visible upconversion fluorescence in Er3+ doped NT glass can be used in color display, undersea communication, and infrared sensor. (C) 2003 American Institute of Physics.