Downconversion in Pr3+–Yb3+ co-doped ZBLA fluoride glasses

Abstract : Fluorozirconate ZBLA glasses with molar composition 57ZrF4–34BaF2–5LaF3–4AlF3–0.5PrF3–xYbF3 (from x=0 to 10) were synthesized to evaluate the rate of the conversion of visible photons into infrared photons. The emission spectra in the near infrared (NIR) at 950–1100 nm and the luminescence decays in the visible and NIR indicate an energy transfer from Pr3+ to Yb3+ upon blue excitation of Pr3+ at 440 nm. The energy transfer efficiency increases with Yb3+ concentration to reach 86% with 0.5Pr3+–10Yb3+ co-doping (in mol%). However, the quenching of the Yb3+ emission strongly reduces the efficiency of the downconversion process: the decay time values decrease from 600 µs (x=0.5 mol%) to 85 µs (x=10 mol%).