Femtosecond-Level Frequency Transfer at 10 GHz over Long Fiber Link with Optical–Electronic Joint Compensation

We report a fiber-optic 10 GHz frequency transfer technique based on an optical–electronic joint phase compensator. A highly stable frequency signal at 10 GHz was transferred in a 50-km long fiber link by using this technique. Two key parameters of the frequency dissemination, the timing fluctuation and frequency stability were both measured. The experimental results show the root-mean-square timing fluctuation of the transferred microwave is about 103 fs within 10,000 s, and the frequency stability for the transmission link is 2.2 × 10−14 at 1 s and 8.5 × 10−17 at 2000 s. The technique proposed in this paper provides a powerful tool which can be used to transfer atomic clocks (e.g., commercial H-master and Cs clocks) in a long fiber link.