Highly efficient mid-infrared dysprosium fiber laser

A new, highly efficient and power scalable pump scheme for 3 μm class fiber lasers is presented. Using the free-running 2.8 μm emission from an Er 3ô -doped fluoride fiber laser to directly excite the upper laser level of the 6H13?2 ? 6H15?2 transition of the Dy 3ô ion, output at 3.04 μm was produced with a record slope efficiency of 51%. Using comparatively long lengths of Dy 3ô -doped fluoride fiber, a maximum emission wavelength of 3.26 μm was measured