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 BaF₂ concentration and several spectroscopic parameters for rare earths were determined. The ratio of integrated luminescence intensity of the (5)D₀→(7)F₂ transition to that of the (5)D₀→(7)F₁ transition of Eu(3+) decrease significantly with increasing BaF₂ content. The absorption (Er(3+)) and emission (Pr(3+)) 'hypersensitive transitions' of rare earths are shifted in direction to shorter wavelengths with increasing BaF₂ content in glass composition. Emission spectra and their decays corresponding to the main (4)I₁₃/₂→(4)I₁₅/₂ 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 BaF₂ concentration.