Stable radio frequency transfer over fiber based on microwave photonic phase shifter.

We demonstrate a radio frequency (RF) phase-stable transmission over fiber based on microwave photonic phase shifter. In the proposed system, both assistant RF signals are applied to drive two arms of a dual-drive Mach-Zehnder modulator (DMZM), respectively. An optical bandpass filter is followed to filter out the first-order sideband of optical modulated signal. Due to the phase independence between two optical sidebands, the phase perturbation caused by fiber-length variations can be compensated automatically via controlling the direct-current bias voltage of the DMZM. We have performed RF transfer in a 155 km single-mode fiber with a frequency instability of 3.05 × 10 at 10,000 s averaging time.