Rare earths in lead-free oxyfluoride germanate glasses.

Spectroscopic properties of rare earths in lead-free oxyfluoride germanate glasses were studied. The absorption and luminescence spectra of Eu 3+ , Pr 3+ and Er 3+ ions were examined as a function of BaF 2 concentration and several spectroscopic parameters for rare earths were determined. The ratio of integrated luminescence intensity of the 5 D 0 → 7 F 2 transition to that of the 5 D 0 → 7 F 1 transition of Eu 3+ decrease significantly with increasing BaF 2 content. The absorption (Er 3+ ) and emission (Pr 3+ ) ‘hypersensitive transitions’ of rare earths are shifted in direction to shorter wavelengths with increasing BaF 2 content in glass composition. Emission spectra and their decays corresponding to the main 4 I 13/2 → 4 I 15/2 laser transition of Er 3+ were also analyzed. Quite long-lived NIR luminescence of Er 3+ is observed for lead-free glass samples with low BaF 2 concentration. [ABSTRACT FROM AUTHOR]