Large-Mode-Area Double-Cladding Photonic Crystal Fiber Laser in the Watt Range at 980nm

We report on a quasi-three-level large-mode-area double-clad Yb-doped fiber laser that adopts a linear cavity consisting of a 0° fiber end and a cavity mirror. Two kinds of Yb−doped photonic crystal fiber (PCF) with different inner-clads (170 µm and 200 µm) and absorption coefficients (4.5 dB/m and 3 dB/m) are used as the gain media. By optimizing the structure and elements of the cavity, maximum output powers of 1.24 W and 1.1 W were yielded with optical conversion efficiencies of 7.8% and 6.8% when the fiber lengths were 25 cm and 40 cm with 170 µm and 200 µm inner-claddings, respectively.