Enhanced 2 μm emission of Yb–Ho doped fluorophosphates glass

In this paper, 2 μm emission spectra of Yb–Ho doped fluorophosphate glass are investigated and compared with Yb–Tm–Ho doped fluorophosphate glass. The 2 μm emission intensity of Yb–Ho doped fluorophosphate glass is much stronger than that of Yb–Tm–Ho doped fluorophosphate glass, exhibiting that Yb–Ho doping is an appropriate doping system to 2 μm application. As the doping concentration of Yb 3+ ions in Yb–Ho doped fluorophosphate glass increases, the 2 μm emission intensity increases monotonously and possesses a maximum for 10% Yb ions concentration. Therefore, 10% is the optimization of Yb ions doping concentration for 2 μm emission. Otherwise, the up-conversion emission of Ho 3+ ions is also studied. Combining with the energy transfer processes, the mechanism is discussed.