2875 nm Lasing From Ho3+-Doped Fluoroindate Glass Fibers
Ho<sup>3+</sup>-doped fluoroindate glass fibers (FIGFs) based on InF<sub>3</sub>-GaF<sub>3</sub>-ZnF<sub>2</sub>-BaF<sub>2</sub>-SrF<sub>2</sub>-YF<sub>3</sub>-LiF-PbF<sub>2</sub> glasses were fabricated by using a rod-in-tube method. By using a 92-cm-long Ho<sup>3+</sup>-doped FIGF as the gain medium and a 1120-nm fiber laser as the pump source, lasing at 2875 nm was obtained for a threshold pump power of 278 mW. By further increasing the pump power to 1224 mW, the obtained maximum output power was about 54.5 mW. The corresponding slope efficiency was about 6%. To the best of our knowledge, this is the first time to report lasing at 2875 nm from Ho<sup>3+</sup>-doped FIGFs.