A 51.3 W, sub-kHz-linewidth linearly polarized all-fiber laser at 1560 nm

We demonstrate a continuous-wave high output power and narrow linewidth all-fiber master oscillator power amplifier laser at 1560 nm. The laser output power is 51.3 W with 36.38% optical-to-optical conversion efficiency and a linewidth of 0.865 kHz. The measured signal-to-noise ratio is 49 dB, and the polarization extinction ratio is greater than 20 dB. The laser can be used for high-efficiency nonlinear frequency conversion.