The luminescence of a Ge-doped fiber preform excited by 240 nm light was studied. Luminescence at 290 nm, 400 nm, and 650 nm was observed, and lifetimes were measured, as well as the spatial profiles. For the first two components, the spatial profile is different from the index profile and the absorption profile, while the 650 nm luminescence follows the index profile. We also measured different lifetimes at different positions across the core.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.