Fluorescence waveforms and coupled energy levels in Er3+:ZBLAN

Abstract Time-resolved fluorescence data was obtained from a number of levels in Er3+:ZBLAN glasses where the fluorescing level was populated by the decay of a higher level. The waveforms were substantially different from those obtained by direct pumping into the levels and care had to be exercised in the analysis of the data to derive a self-consistent physical interpretation. The fluorescing levels were the 4I13/2, 4I9/2 and 4F9/2 levels which were populated by the decay of the 4I11/2, 4F9/2, and ( 4 S 3/2 + 2 H 11/2 ) levels respectively. A rate-equation analysis was used to explain the observed behaviour. Particularly interesting was the population dynamics of the 4F9/2 level where the lifetime of the populating ( 4 S 3/2 + 2 H 11/2 ) level was strongly dependent on the Er3+ concentration.