10 W widely tunable narrow linewidth double-clad fiber ring laser

Summary form only given. We report on a widely tunable narrow linewidth ytterbium-doped fiber ring laser device with a linearly polarized output power of 10 W. The Large Mode Area (LMA) core of the 20 m long fiber had a diameter of 10 /spl mu/m and was doped with 1000 ppm ytterbium. The core was transverse single-mode for wavelengths above 1 /spl mu/m. The pump-cladding was D-shaped in order to improve the pump light absorption. As pump source we used a fiber coupled 980 nm laser diode. The small quantum defect between the pump and the laser wavelength enables a very high efficiency. At maximum pump power of nearly 32 W a linearly polarized output power of 10 W with a slope efficiency of 68% with respect to the absorbed pump power at a wavelength of 1080 nm was achieved.