Silica-based sol±gel glasses activated by Er 3‡ ions are attractive materials for integrated optics (IO) devices such as frequency upconverters and optical ampli®ers. Monolithic erbium-activated silica xerogels with erbium content ranging from 0 up to 40 000 ppm were prepared by the sol±gel technique. Samples were densi®ed by thermal treatment in air at 950°C for 120 h. The densi®cation degree and the relative content of hydroxyl groups were studied by Raman spec-troscopy. Refractive indices were measured at 632.8 and 543.5 nm by a prism coupling technique. Green to blue and violet upconversion luminescence upon continuous-wave excitation at 514.5 nm was observed for all samples. Emission at 1:5 lm, characteristic of the 4 I 13=2 3 4 I 15=2 transition of Er 3‡ ions, was observed at room temperature for all samples upon continuous-wave excitation at 980 nm. For the 5000 Er/Si ppm-doped xerogel, a photoluminescence was observed and a lifetime of 8 ms for the metastable 4 I 13=2 level was measured. Ó 2001 Elsevier Science B.V. All rights reserved.