Fluorescence from highly-doped erbium fluorozirconate glasses pumped at 800 nm

A study of the fluorescence properties, under 800 nm excitation, of new ZBEAN glasses with Er³⁺ concentrations up to 18 mol% is reported. This represents the highest reported doping concentration for this type of glass. The fluorescence intensity at 550 nm, 1.53 μm and 2.7 μm did not exhibit the expected strong quenching at these high concentrations and the corresponding decay times were consistent with this observation. Cooperative energy transfer between the relevant levels is discussed as a possible explanation of this behaviour.