MICRO-FLUORESCENCE PROFILING OF ERBIUM-DOPED FIBER PREFORMS

A micro-fluorescence technique for profiling the spatial distribution of erbium ions doped into optical fibre preforms is reported. Profiles have been compared using fluorescence at wavelengths of 0.553 and 1.5 mum to identify a critical erbium concentration of about 0.12 wt% Er3 +, where the effects of clustering become apparent. The addition of co re co-dopants has been studied and found to have no significant effect on the active ion distribution. The variation in 1.5 mum fluorescence lifetime with position across the core has been measured. A pronounce d reduction (up to 66%) in this lifetime at the core extremities was o bserved and indicates the presence of local ion environment disorderin g.