Preparation and investigation of Tm 3+ /Ho 3+ co-doped germanate-tellurite glass as promising materials for ultrashort pulse laser

The Tm3+/Ho3+ co-doped germanate-tellurite glasses with good thermal properties were prepared. A flat emission with full width at half maximum (FWHM) = 373 nm at ∼2 μm was observed in the prepared glass upon the 808 nm excitation. Besides, the cross-sections of the prepared glass have been calculated, and the relative small peak absorption cross-sections (σabs) corresponding to the Ho3+: 5I7 → 5I8 is the factor to obtain the flat emission. Moreover, the energy transfer microscopic parameters (CDA) between RE3+ ions have been investigated and quantitatively explained the observation of the flat and broadband emission. Furthermore, when P = 0.2, the gain coefficient becomes positive which indicates the prepared glasses possess superior gain ability. The results indicate that the prepared glasses could be promising candidate for ∼2 μm tunable or ultrashort pulse laser materials.