Ultra-large mode area single frequency anisotropic MOPA with double clad Yb-doped tapered fiber

We demonstrates all-fiber master oscillator – power amplifier delivered 70W output power at 1033.33nm with 8 kHz FWHM linewidth without any problems with SBS. The anisotropic ytterbium doped tapered double clad amplifier with 50 μm MFD and polarization extinction ratio about 30 dB is developed as a burst stage. The output radiation demonstrated perfect beam quality (M 2 =1.03/1.08).