Effect of the ytterbium concentration on the upconversion luminescence of Yb 3+/Er 3+ co-doped PbO–GeO 2–Ga 2O 3 glasses

Abstract

The effect of Yb 3+ concentration on the frequency upconversion (UPC) of Er 3+ in PbO–GeO 2–Ga 2O 3 glasses is reported for the first time. Samples were prepared with 0.5 wt% of Er 2O 3 and different concentrations of Yb 2O 3 (1.0–5.0 wt%). The green (523 and 545 nm) and red (657 nm) emissions are observed under 980 nm diode laser excitation. The dependence of the frequency UPC emission intensity upon the excitation power was examined and the UPC mechanisms are discussed. An interesting characteristic of these glasses is the increase of the ratio of red to green emission, through an increase of the Yb 3+ concentration due to an efficient energy transfer from Yb 3+ to Er 3+.