170 W, single-frequency, single-mode, linearly-polarized, Yb-doped all-fiber amplifier

A 170 W all-fiber linearly-polarized single-frequency sing-mode ytterbium amplifier at 1064 nm with an optical efficiency of 80% is demonstrated. 3.9 m long ytterbium-doped polarization maintaining fiber with a core diameter of 10 μm is used as the gain fiber, which guarantees a diffraction-limited output with a measured M(2) of 1.02. To suppress the stimulated Brillouin scattering, longitudinally varied strains are applied on the gain fiber according to the signal power evolution and the temperature distribution. 7 times increase of the stimulated Brillouin scattering threshold is achieved.