COMPOSITIONAL DEPENDENCE OF INFRARED TO BLUE AND RED CONVERSION LUMINESCENCE IN OXYFLUORIDE GLASS-CERAMICS CO-DOPED WITH TM(3+) AND YB(3+) IONS

The upconversion of infrared radiation into visible light has been studied in heavy metal oxyfluoride glass-ceramics co-doped with Yb3, and Tm3+ ions at 300 K. The general composition of the compounds is 69.9PbF2 + 7.5WO3 + 7.5MO2 + 15YbF3 + 0.1TmF3 (M = Si, Ge, Zr, Te, and Th). Two main upconversion emissions were observed. They are centered at 477 and 775 nm, corresponding to the 1G4 --> H-3(6) and F-3(4) --> H-3(6) transitions, respectively. Slopes of the emission intensity versus excitation power measurements indicate that the blue emission is due to three-photon absorption, while two-photon absorption processes are responsible for the red emission. A comparative method was used to measure the upconversion efficiencies under 16.5 mW/cm2 excitation power. Measurements were made after the compounds were annealed at 450-degrees-C for 4 h. The best conversion efficiencies were obtained for the compound having silicon (Si). They are 28 X 10(-6) for the blue and 18 X 10(-2) for the red emission.