Efficient laser emission at 1191 nm based on Ho3+-doped fluoroaluminate glass in a compact fiber configuration

Efficient laser emission at a wavelength of approximately 1.2 mu m in Ho3+-doped AlF3-based glass fiber is reported for the first time. Lasing was achieved through in -band pumping at 1150 nm. The laser cavity's front-end feedback was facilitated by a (High reflectivity, HR) HR-FBG written in Corning HI1060 fiber, spliced to one end of the Ho3+-doped AlF3-based fiber. Fresnel's reflection of the gain fiber provided the other end feedback. The laser performance was characterized by different fiber lengths, and a 31 cm-long fiber achieved a maximum slope efficiency of 70.5 % and a maximum output power of 8.3 W. Furthermore, a series of (Low reflectivity, LR) LR-FBGs written in HI1060 fiber with different reflectivity values were used to replace the Fresnel reflection at the emission end of the gain fiber. The maximum slope efficiency was found to be 54.2 % for a LR-FBG with a reflectivity of 10 %. These results confirm that AlF3-based fiber can potentially serve as gain fiber for higher-power fiber lasers.