Frequency comb-based one-way RF frequency transfer across a 880-m-long outdoor atmospheric link with 10(-16) instability

Abstract

We introduce RF frequency dissemination and synchronization system through an outdoor 880-m-long beam path with sub-picosecond timing jitter. The 880-m-long link is configured as a round-trip beam path between rooftops of two independent multi-story buildings. The reference RF frequency of 1.25 GHz is extracted from the fifth harmonic component of the 250 MHz optical frequency comb, which is propagated through the turbulent 880-m beam path. Excess phase noise during the propagation is measured by frequency mixing between the reference and transferred RF signals. After the suppression of the excess phase noise by using a voltage controlled phase shifter, we achieved the instability of 4.5×10