2875 nm Lasing from Ho³⁺-Doped Fluoroindate Glass Fibers

Ho³⁺-doped fluoroindate glass fibers (FIGFs) based on InF₃-GaF₃-ZnF₂-BaF₂-SrF₂-YF₃-LiF-PbF₂ glasses were fabricated by using a rod-in-tube method. By using a 92-cm-long Ho³⁺-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 Ho³⁺-doped FIGFs.