Phase conjugation frequency dissemination based on harmonics of optical comb at 10^−17 instability level

We demonstrate a phase conjugation frequency dissemination scheme using an optical frequency comb as a coherent source. After the comb's radio frequency is detected by a photodiode, its repetition frequency's first harmonic is used to modulate a laser, which is injected into a 10 km fiber link. The round-trip signal is mixed with the triple harmonic thereby obtaining a signal that is immune to the fluctuation at the remote end. This method results in frequency instability of 1.1×10(-17) at 10(4) s. Our scheme provides a potential approach to deliver coherent frequencies to many places with high stability.