FLUORESCENCE LINE NARROWING IN ERBIUM-DOPED SILICA FIBERS

The properties of erbium-doped silica fiber amplifier are significantl y modified by the addition of only few percents of aluminium. For exam ple, at room temperature, the 1.5 mum emission linewidth is multiplied by a factor two. In order to improve our knowledge on rare-earth tran sition broadening mechanism, primarily in fibers, nonresonant fluoresc ence line narrowing measurements were performed on erbium-doped silica fibers codoped with either aluminium or germanium, at low temperature s. An important variation in-site distribution and Stark splitting was found depending on the matrix.