BaF2 modified Cr3+/Ho3+ co-doped germanate glass for efficient 2.0 μm fiber lasers

The influence of BaF 2 on the physical and spectroscopic properties of Cr 3+ /Ho 3+ co-doped germanate glass is investigated systematically by differential scanning calorimeter , excitation and emission spectra , as well as dynamic decay lifetime. The intense and broad absorption band of Cr 3+ provides a selective pump scheme for obtaining an efficient 2.0   μm emission of Ho 3+ , the OH − absorption coefficient, on the other hand, is decreased as low as 1.08   cm −1 , which both highly conducive to obtain an intense 2.0   μm emission of Ho 3+ . In addition, the crystal-field parameter D q / B of Cr 3+ -doped glasses is also calculated to study the influence of BaF 2 on the local environment of activators and sensitizers. Further theoretic calculation shows that the largest absorption and emission cross-sections of Ho 3+ near 2.0   μm are as high as 4.6 and 5.2 (×   10 −21   cm 2 ) in the 10   mol% BaF 2 modified Cr 3+ /Ho 3+ co-doped glass and the maximum energy transfer efficiency from Cr 3+ to Ho 3+ is about 42.5%. All results suggest that this BaF 2 modified Cr 3+ /Ho 3+ co-doped glass is very suitable for a high-efficient 2.0   μm fiber lasers with flexible pump sources.