Sensitization of Ho3+ on the 2.7 µm emission of Er3+ in (Y0.9La0.1)2O3 transparent ceramics

The 2.7 µm emission properties of Er3+ in Er3+/Ho3+:(Y0.9La0.1)2O3 transparent ceramics prepared by conventional ceramic method have been studied pumped at 980 nm as a function of Ho3+ concentration. Absorption spectra, upconversion, mid- and near-infrared emission spectra, as well as fluorescence decay curves have been investigated. The reduced green emission and the enhanced red emission, the much enhanced 2.7 µm emission and the significantly reduced 1.5 µm emission as well as the fluorescence lifetime demonstrate that Ho3+ is a promising sensitizer to effectively activate Er3+ for 2.7 µm emission with an optimum doping concentration Ho3+ to Er3+ ratio at 0.5:1. Large values of Judd-Ofelt parameter Ω2 = 4.93 × 10-20 cm2 and spectroscopic quality factor X = 7.85, along with the emission cross section σe = 3.88 × 10-20 cm2 for 2.7 µm emission have been obtained in Er3+/Ho3+ co-doped (Y0.9La0.1)2O3 ceramic. These results suggest that Er3+/Ho3+:(Y0.9La0.1)2O3 transparent ceramic is a promising material for the applications of mid-infrared lasers.