Up-conversion fluorescence in Er3+ :Yb3+ co-doped oxy-fluoride compound materials' based on GeO2

Six Er3+ :Yb3+ co-doped samples were prepared based on GeO2. Their fluorescence spectra under 858 nm semiconduct laser and 930 nm diode laser excitation were also measured respectively. It was found that the relative intensities of fluorescence pumped under 930 nm diode laser are commonly stronger than that of pumped under 858 nm semiconduct laser. Furthermore, the relative intensities of fluorescence of Ge4 and Ge5 samples are far stronger than the other four samples under the two kinds of lasers excitation. Their strong green luminescences were observed with naked-eye at daytime. Their up-conversion mechanism pumped under 930 nm diode laser was analyzed.