High-power and near-shot-noise-limited intensity noise all-fiber single-frequency 1.5 µm MOPA laser.

An all-fiber high-power and broad-frequency-band near-shot-noise-limited kHz-linewidth (Δν ~1.7 kHz) single-frequency master-oscillator power amplifier (MOPA) laser at 1.5 µm is demonstrated. To significantly suppress the intensity noise of seed laser and mitigate the detrimental effects of amplified spontaneous emission and stimulated Brillouin scattering in fiber amplifiers, more than 23 W of a stable low noise single-frequency laser output is achieved with a relative intensity noise of < -150 dB/Hz @0.5 mW (near to the shot-noise limit: -152.9 dB/Hz) in the frequency band from 0.1 to 50 MHz. It is believed that the achieved laser performance of ultra-low intensity noise and high-power output make the laser source become a promising candidate in further applications, such as cold atom optical lattice, quantum key distribution, and gravitational wave detection.