EFFICIENT BLUE AND RED UP-CONVERSION OF INFRARED LIGHT IN OXYFLUORIDETELLURITE CERAMICS

The upconversion of 966nm infrared radiation into visible light has be en studied in 69.9 PbF2 + 7.5WO3 + 7.5TeO2 : 15YbF3 : 0.1TmF3 ceramic. Several upconversion emission bands were observed in the spectral ran ge of 460 and 830nm. The blue and red emission bands are centered at 4 78 and 775nm, respectively. Intensity versus excitation power measurem ents confirm that the red emission was due to the two photon absorptio n while the blue emission was a result of three photon absorption proc esses. Absolute fluorescence efficiencies were determined at room temp erature for 16.5mW/cm2 excitation intensity, using a comparative metho d. Values obtained for the red and blue emissions are 5.8 10(-2) and 7 .5 10(-6), respectively in the compound prepared at 900-degrees-C. Ann ealing the compound at 460-degrees-C for four hours increases the upco nversion efficiencies of the 478 and 775 nm emissions, about two times . Temperature dependence of these upconverted emissions was investigat ed for the annealed and not annealed samples.