Controllable optical properties between Ho3+: 5I7 → 5I8 and Tm3+: 3F4 → 3H6 transitions in germanosilicate glasses

Diode-pumped solid-state 2 μm lasers have seen rapid development for their efficient operation, compact size, and stable performance. In this work, doped germanosilicate (SiO2-GeO2-Ga2O3-Lu2O3) glasses with varying Tm3+/Ho3+ concentrations exhibiting excellent physical and optical characteristics were successfully prepared. Thermal and structural properties were analyzed by the measured DSC and Raman spectra. An evident efficient wide absorption band near 770-830 nm demonstrated the feasible energy transfer between Tm3+: 3F4 → 3H6 and Ho3+: 5I7 → 5I8 transitions. Meanwhile, combining with Judd-Ofelt theory, super predicted spontaneous emission probabilities were obtained, which are beneficial to obtain fine laser action for solid-state lasers. This is a first study to demonstrate that a tunable fluorescence peak (1.8-2.05 μm) can be obtained by modulating the combined effects between two luminous activation centers. Therefore, the results indicate a promising rare-earth doped glass host for solid-state 2 μm lasers.