Visible up-conversion and NIR luminescence studies of LiAl5O8:Er phosphor co-doped with Yb3+ and Zn2+

The frequency up-conversion, an efficient laser emission and amplification in Er3+:LiAl5O8 phosphors co-doped with Yb3+ and Zn2+ phosphor powders in the 520-560, 640-680 nm regions and at similar to 1.5 mu m, respectively, have been reported. The emission corresponds to the H-2(11/2), S-4(3/2)-> I-4(15/2), F-4(9/2)-> I-4(15/2) and I-4(13/2)-> I-4(15/2) transitions upon direct excitation into the intermediated I-4(11/2) level using similar to 980 nm radiation from a CW laser. Possible mechanisms involved for the up-conversion processes based on the energy level matching scheme, the pump-power dependence and the dynamical behaviour have been discussed. The effect of the addition of Yb3+ and Zn2+ for the amplification in the 1.5 mu m eye-safe telecommunication window has been elaborated and characterized in detail.