Measurement of the energy transfer and upconversion constants in Er-Yb-doped phosphate glass

A simple method to measure the ytterbium-to-erbium energy transfer and the cooperative upconversion constants in a phosphate laser glass is proposed. The technique is based on the experimental acquisition of the luminescence decay from the Er3+ I-4(13/2) metastable level at 1.5 mu m as a function of time and on a suitable fit of the experimental data. The fitting procedure relies on a simplified model of the Er-Yb system and makes use of a numeri cal solution of the rate equations to describe the dynamics of the populati ons, showing considerable sensitivity to the fitting parameters. The result s obtained are in fairly good agreement with previous data reported in the literature.