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 Er³⁺-doped fluoride fiber laser to directly excite the upper laser level of the H_13/26→H_15/26 transition of the Dy³⁺ ion, output at 3.04 μm was produced with a record slope efficiency of 51%. Using comparatively long lengths of Dy³⁺-doped fluoride fiber, a maximum emission wavelength of 3.26 μm was measured.