Study on the green upconversion saturation in Er3+ doped oxyfluoride tellurite glass

The upconversion emission spectra of Er3+ doped oxyfluoride tellurite glasses excited by 808 nm laser diode (LD) were measured. The dependence of 550 nm upconversion emission on the excitation intensity was analyzed. Quadratic intensity dependence was only observed at weak excitation intensity. With increasing the excitation intensity, saturation was turned out. The experimental results were fitted to a model based on the rate equations.