Spectroscopy and frequency upconversion of Er3+ ions in fluorotellurite glasses

Abstract

In this work we report the optical properties and upconversion luminescence of Er3+ions in TeO2–WO3–PbO–BaF2 and TeO2–TiO2–Nb2O5–BaF2fluorotelluriteglasses and their comparison with those of TeO2–TiO2–Nb2O5 glass. The optical properties of Er3+ions have been established in terms of absorption and emission spectra and lifetime measurements. The 1.5 μm emission cross-section has been determined from the line shape of the emission spectrum and the calculated emission probability for the 4I13/2 level. The highest emission cross section (6.9 × 10−21 cm2) corresponds to the TeO2–TiO2–Nb2O5–BaF2 glass with a figure of merit for the bandwidth of 524.4 cm2 nm. Upconversion emissions at 530, 548 nm, and 660 nm have been obtained under infrared excitation at 800 nm in the 4I9/2 level and compared with those obtained under one photon excitation. The green emission corresponding to the 4S3/2 → 4I15/2 transition is dominant in all glasses. The excitation wavelength dependence of the upconverted luminescence together with its time evolution after infrared pulsed excitation suggest that energy transfer upconversion processes are responsible for the green upconversion luminescence.