47 GHz narrow linewidth linear polarized fiber amplifier injected by a simple fiber oscillator laser seed source

In this paper, we demonstrate 47 GHz linear polarized fiber amplifier injected by a simple fiber oscillator laser seed source with narrow linewidth and near diffraction-limited beam quality. Output powers of 419 W, 778 W, and 1107 W are achieved with 3dB linewidth of 26.5 GHz, 41 GHz, and 47 GHz, respectively. The M2 is 1.25 in the x-direction and 1.23 in the y-direction at the maximum laser power, respectively. The measured PER is large than 96% during the power scaling process. However, The SRS is observed when the laser power is 1107, the SNR is about 47dB, which means that the SRS effect has become a serious limitation for further power scaling of such PM-amplifier seeded by the fiber oscillator laser seed source.