Efficient 2.0 μm emission in Er3+/Ho3+ co-doped barium gallo-germanate glasses under different excitations for mid-infrared laser

We report the visible up-conversion, near to middle infrared luminescence, and energy transfer mechanism of Er3+/Ho3+ co-doped barium gallo-germanate glasses under 980 and 1550 nm excitations, respectively. The 2.0 μm emission lifetime of the present glass is as high as 5.67 ms with the corresponding energy transfer efficiency of 70.0% from Er3+: 4I13/2 to Ho3+: 5I7 when pumped by 980 nm laser diode. In addition, the enhanced 2.0 μm emission is also obtained upon excitation of 1550 nm due to the efficient energy transfer from Er3+ to Ho3+. Meanwhile, the calculated maximum gain is 2.13 cm−1 at 2024 nm. These results suggest that Er3+/Ho3+ co-doped barium gallo-germanate glasses is a potential material for 2.0 μm fiber laser.