Spectroscopic evidence for oxide dopant sites in GeS2-based glasses using visible photoluminescence from Pr3+ probe ions

Photoluminescence at wavelengths between 600 and 660 nm was observed in Pr3+-doped GeS2-based glasses. The spectral profile of the 3P0→3H6 transition was found to be highly sensitive to the presence of oxide impurities in the glass. The main peak at 632 nm was identified with sulphide-dominated dopant sites, while the shoulder at 614 nm was attributed to oxide-dominated sites. Results demonstrate that the luminescence spectrum of Pr3+ at 610–635 nm reveals the presence and concentration of oxygen-rich sites in Pr3+-doped GeS2-doped glasses. The method is shown to be sensitive to concentrations of GeO bonds down to 200 ppmw level.