Ytterbium-induced energy-transfer upconversion enhancement in Nd3+/Pr3+-codoped PbGeO3–PbF2–CdF2 glass excited at 810 nm

The effect of ytterbium ions upon energy transfer (ET) excited upconversion emission in Nd3+/Pr3+-codoped PbGeO3–PbF2–CdF2 glass under 810 nm diode laser excitation is investigated. The results revealed that the presence of Yb3+ ions in the Nd3+/Pr3+-doped sample yields a fourfold enhancement in the visible and near infrared upconversion luminescence. The dependence of the upconversion process upon the excitation power, Nd3+, and Yb3+ concentrations is examined. The results indicated that ytterbium plays a major role in the ET upconversion process by bridging the 810 nm neodymium excitation to praseodymium ions. The population of the Pr3+ ions 3P0 emitting level was accomplished through a multi-ion interaction involving ground-state and excited-state absorption of pump photons at 810 nm by the Nd3+ followed by successive ET involving the Nd3+–Yb3+ and Yb3+–Pr3+ pairs. There is also direct ET Nd3+–Pr3+.