A round-trip fiber-optic time transfer system using bidirectional TDM transmission

We propose a round-trip fiber-optic time transfer scheme over single optical fiber utilizing the same wavelength in both directions. It can suppress the impact of the Rayleigh backscattering and the dispersion-induced symmetric deviation over fiber link by using bidirectional time division multiplexing (TDM) mechanism. A 200 km time transfer over single optical fiber with identical optical wavelength in both directions is demonstrated. The measured stabilities in terms of TDEV are less than 40ps/s and 10ps/d, respectively. The uncertainty induced by uncalibrated fiber links up to 200km is less than 27 ps, which is mainly limited by the performance of used time interval counters.