Cr/sup 4+/-doped silica-based optical fibres: absorption and fluorescence properties

Summary form only given. We report on a Cr/sup 4+/-doped silica optical fibre, drawn from a preform prepared by modified chemical vapour deposition. The alumina-silicate core fibre contains aluminium and chromium, incorporated by the classical solution doping technique. We show that all the chromium ions present in the fibre are stabilized into the Cr/sup 4+/ oxidation state. Results on room and low temperature absorption and fluorescence are presented, and interpreted on the basis of the Tanabe-Sugano ligand-field model for transition metal ions.