Porous alumina covered with spin-on erbium-doped silica sol-gel film, subjected to thermal processing above 973 K, exhibited strong Er-related photoluminescence at 1.53 mu m at room temperature. The intensity of the photoluminescence increases with the thickness of both the porous alumina and the spin-on film, the latter being built up layer-by-layer to avoid cracking. SIMS analysis shows that the Er penetrates throughout the porous alumina. The sol-gel method is a flexible technique, compatible with planar silicon-based technology, for fabricating lanthanide-containing luminescent structures in porous materials on silicon.