Frequency up-conversion luminescence properties and mechanism of Tm^sup 3+^/Er^sup 3+^/Yb^sup 3+^ co-doped oxyfluorogermanate glasses

Oxyfluoride glasses were developed with composition 60GeO2·10AlF^sub 3^·25BaF^sub 2^·(1.95-x) GdF^sub 3^· 3YbF^sub 3^·0.05TmF^sub 3^·xErF^sub 3^ (x = 0.02, 0.05, 0.08, 0.11, 0.14, 0.17) in mole percent. Intense blue (476 nm), green (524 and 546 nm) and red (658 nm) emissions which identified from the ^sup 1^ G ^sub 4^[arrow right]^sup 3^ H ^sub 6^ transition of Tm^sup 3+^ and the (^sup 2^ H ^sub 11/2^, ^sup 4^ S ^sub 3/2^) [arrow right] ^sup 4^ I ^sub 15/2^, ^sup 4^ F ^sub 9/2^[arrow right]^sup 4^ I ^sub 15/2^ transitions of Er^sup 3+^, respectively, were simultaneously observed under 980 nm excitation at room temperature. The results show that multicolor luminescence including white light can be adjustably tuned by changing doping concentrations of Er^sup 3+^ ion or the excitation power. In addition, the energy transfer processes among Tm^sup 3+^, Er^sup 3+^ and Yb^sup 3+^ ions, and up-conversion mechanisms are discussed.[PUBLICATION ABSTRACT]