Towards lead-free oxyfluoride germanate glasses singly doped with Er3+ for long-lived near-infrared luminescence

• Erbium-doped lead-free germanate glasses modified by BaF2 were prepared.
• The bonding parameter is reduced with increasing BaF2 content.
• The 4I15/2 − 2H11/2 hypersensitive transition is blue shifted with increasing BaF2 content.
• Luminescence spectra due to main 4I13/2 − 4I15/2 laser transition of Er3+ were detected.
• Long-lived NIR emission of Er3+ is observed for glass samples with low BaF2 content.

Spectroscopic properties of Er3+ ions in lead-free oxyfluoride germanate glasses were studied. The absorption and luminescence spectra of Er3+ ions were examined for glass samples with low and high BaF2 content. From absorption spectra the bonding parameter was calculated and its value is reduced with increasing BaF2 content. The maximum of absorption peak due to 4I15/2 − 2H11/2 hypersensitive transition is shifted to shorter wavelengths (blue shift) with increasing BaF2 content. Luminescence spectra and their decays corresponding to main 4I13/2 − 4I15/2 laser transition of Er3+ are also presented and discussed. Quite long-lived near-infrared luminescence of Er3+ is observed for lead-free glass samples with low BaF2 concentration.