Spectroscopic analysis of up conversion luminescence in doped halogeno-antimonite glass

The up-conversion emission of Nd3+, Sm3+ and Er3+ has been studied in a new halogeno-antimonite glass with the chemical composition 80 Sb2O3 – 10 ZnBr2 – 10 KCl. Doping concentration was 0.2 mol% of lanthanide (Ln) ions. Rare earths were introduced as fluorides LnF3 that were further converted into oxides. Main physical properties of base glass were measured, including density, thermal expansion, characteristic temperatures, refractive index and optical transmission. The amount of residual hydroxyls was calculated from the OH absorption band around 3000 nm. The recorded up-conversion emission lines are λem = 536 nm for Nd3+ pumped at 805 nm; λem = 563 nm, 600 nm, 631 nm and 645 nm for Sm3+ pumped at 945 nm; λem = 531 nm for Er3+ pumped at 798 nm. Co-doped glass (0.1 Yb3+ + 0.1 Er3+) pumped at 980 nm has three emission lines at 524 nm, 545 nm and 650 nm. Corresponding transitions have been identified and the mechanisms ruling the up-conversion process is discussed. They include excited state absorption (ESA), energy transfer (ET) cooperative energy transfer (CET), emission assisted by phonon (EAP), multiphonon relaxation (MR) and cross- relaxation (CR).