Determination of upconversion state lifetime and upconversion mechanisms of Er3+ in tellurite glasses

We compared the lifetime values of the upconversion state for Er3+doped tellurite glass with and without halide ions as determined by direct excitation mechanism, with the results measured by upconversion excitation method. The results indicate that upconversion excitation lengthens the lifetime value largely compared with the direct excitation. The intensity of the upconversion fluorescen ce of the two kinds of glasses was discussed, which showed that it becomes stron ger with the addition of the halide ions than that without the halide ions. The upconversion mechanisms and power-dependent intensities were also determined and explained.