Low-noise high-power dual-frequency MOPA laser with an NPRO seed

Dual-frequency lasers are significant in fields like photonic microwave sources, optical carrier lidar, and heterodyne laser interferometry. Increasing the power of dual-frequency lasers is crucial for expanding their applications. However, achieving high-power dual-frequency lasers with low noise remains a challenge. In this work, we demonstrate a low-noise, high-power dual-frequency laser in a master-oscillator-power-amplifier (MOPA) configuration. In this setup, a dual-frequency monolithic nonplanar-ring-oscillator (NPRO) serves as the seed, and an ytterbium-doped fiber amplifier (YDFA) is used to boost the optical power. The MOPA laser achieves a dual-frequency laser power up to 5 W at 1064 nm and maintains the phase noise of the beat signal at 5.78 GHz as low as -116.6 dBc/Hz at 10 kHz and -152.3 dBc/Hz at 10 MHz. To quantify the additional phase noise to the beat signal from the fiber amplifier, we established a theoretical model, which reveals that this noise is negligible in our system. We anticipate that our model can be extended to analyze the phase noises of other dual-frequency laser systems, and our MOPA laser will enhance the capabilities of dual-frequency laser applications in industrial, airborne, and spaceborne environments.