Multi-access fiber-optic radio frequency transfer with passive phase noise compensation.

In this Letter, we propose and demonstrate a multi-access fiber-optic radio frequency dissemination with passive phase noise cancelation. A forward phase-conjugated signal is generated at the local site by frequency mixing between the standard signal and the round-trip probe signal. A stable frequency signal is achieved by frequency mixing the tapped forward phase-conjugated signal and the backward probe signal at an arbitrary point along the fiber link. Different wavelengths for forward and backward directions are employed to efficiently suppress the effect of backscattering. At the same time, the increase of bidirectional asymmetry with the increase of user ends is avoided by employing the same wavelengths for all user ends. A multi-access frequency transfer over a 45 km fiber link based on the proposed scheme is demonstrated. The radio frequency signals with relative frequency stabilities of 10/20,000  s level are reproduced at two points of 5 and 40 km far from the local site along the fiber link, respectively.