Tunable, linearly polarized, intrinsically single-mode fiber laser using a 40-μm core-diameter Yb-doped photonic-crystal fiber

We report a 40-μm core-diameter, Yb-doped, air-clad photonic crystal fiber laser operating continuous-wave with intrinsic single-transverse-mode beam quality (M2 ∼ 1.25). The laser was tunable over the 1020-1050 nm range, exhibited a spectral linewidth ∼5 GHz, was temporally stable and linearly polarized with a polarization extinction ratio >93%. The maximum output power obtained was ∼14 W (limited by the available pump power).