Effect of ytterbium co-doping on erbium clustering in silica-doped glass

The effect of ytterbium co-doping on erbium ion clustering in silica-based glass was studied. It was experimentally shown that the pump-to-signal conversion efficiency could be significantly increased if the number of Yb 3+ ions in the fiber core was 20 times higher than the number of Er 3+ ions. Estimations of the number of Er 3+ ions in clusters confirmed a decrease in their clustering at high Yb concentrations.