1.54 and 1.75 μm infrared luminescence of Y2O3:Er3+

A new 1.75 μm infrared emission transition of Y2O3:Er3+ is assigned to the 4S3/2 → 4I9/2 transition of Er3+ ions situated at the C2 sites of cubic RE2O3 (RE = Y, Gd, Lu). The intensities of features in the 1.54 μm 4I15/2–4I13/2 absorption transition due to Er3+ at S6 and C2 sites are consistent with the site occupation ratio and the relative magnetic dipole–electric dipole intensity contributions of Er3+ at the different sites. The 1.54 μm emission lines are predominantly from Er3+ ions at C2 sites. The different behaviours of the emission intensities 1.75 and 1.54 μm groups with change in Er3+ dopant ion concentration, preparation technique, Yb3+ co-doping, temperature change and different excitation line are rationalized.