Theoretical and experimental investigation of over 1 W single-mode Yb-doped fiber laser at 980 nm

Based on rate equations, this paper gives expressions of the output power, the pump power threshold, the slope efficiency, and the fiber optimal length of the quasi-three-level Yb-doped fiber laser. The laser gain relationship between quasi-three-level mode and four-level mode in Yb-doped fiber laser is also given, which provides a theoretical basis for suppressing the four-level transmissions and determining the range of the fiber length. In the experiment, a plano-plano cavity consisting of two 0° fiber ends is adopted as cavity mirrors. A quasi-three-level Yb-doped single-mode fiber laser totally emitted 1.32 W of single-mode laser output at 980 nm from two ends with the slope efficiency of 75.3% when the fiber length is 36.5 cm. The corresponding optical conversion efficiency is 66% from incidence pump power at 946 nm to the laser power at 980 nm. Besides, a total power of 15 mW at 490.8 nm is obtained by frequency doubling the laser at 980 nm with BIBO with the conversion efficiency of 1.1%.