Spectroscopic properties and energy transfer parameters of Yb3Â +/Tm3Â + co-doped fluorogermanate glasses

Yb3 +/Tm3 + co-doped fluorogermanate glasses have been prepared by the melt-quenching method. Their luminescent properties were investigated by absorption spectra, excitation and emission spectra, and dynamic luminescence decay curves. The energy transfer parameters were analyzed by the phonon sideband theory and the energy transfer mechanism between Yb3 + and Tm3 + was proposed. An efficient 1.8 μm luminescence with reduced up-conversion emission is achieved under excitation of 980 nm laser diode. It is found that the emission at 800 nm is the main path of energy loss in the up-conversion process and it can be lowered at a higher Tm3 + doping level. In addition, the forward energy transfer parameter from Yb3 + to Tm3 + is approximately two orders of magnitude greater than the backward one, supporting efficient 1.8 μm emission.