SPATIAL-DISTRIBUTION OF UV-EXCITED LUMINESCENCE IN GE-DOPED FIBER PREFORMS

The spatial distribution of the 240 nm absorption and its associated l uminescence measured in a Ge-doped silica optical fibre preform are pr esented. The 400 nm luminescence was found to be maximum at the edges and near the centre of the core, while the absorption follows the Ge c oncentration in the core, implying that the luminescence is a nonlinea r function of the Ge concentration. Quenching of the luminescence by e ither the defect or Ge concentration is proposed to explain this obser vation.