New approach for preparation of high-purity sulfide-germanium glasses doped with praseodymium

It has been established that rare earth elements (REE), as alloying additives, are a significant source of hydrogen and oxygen impurity in glasses of Ge – S and Ge – As – S systems. A method has been developed that includes loading germanium in the form of monosulfide and high-temperature annealing of REE and their compounds in sulfur vapor, reducing content of absorbing impurities in sulfide-germanium glasses. Samples of especially pure glasses of Ge42.5S57.5 and Ge35As10S55 composition doped with praseodymium up to 1450 ppm(at) were prepared. The impurity content of hydrogen and oxygen in the form of SH-groups and Ge–O in the best glass samples was 0.02–0.06 ppm(wt) and <0.1– 0.2 ppm(wt), respectively. The absorption coefficients and the absorption cross section were determined for various energy states of the Pr3+ ion in Ge35As10S55 glass. The luminescence intensity of Pr3+ ions in the spectral ranges 2.0–2.8 and 3.5–5.8 µm in Ge42.5S57.5 glasses is by 3 orders of magnitude higher than in Ge35As10S55 glasses.