Simple stabilized radio-frequency transfer with optical phase actuation

We describe and experimentally evaluate a stabilized radio-frequency transfer technique that employs optical phase sensing and optical phase actuation. This technique is achieved by modifying existing optical frequency transfer equipment and also exhibits advantages over previous stabilized radiofrequency transfer techniques in terms of size and complexity. Acousto-optic modulators (AOMs) are used to modulate an optical carrier. Stabilization of frequency fluctuations in the link is achieved by steering the frequency of one of the AOMs. We demonstrate the stabilized transfer of a 160-MHz signal over a 166-km fiber optical link, achieving an Allan deviation of 9.7 × 10-12 at 1 s of integration, and 6.4 × 10-15 at 104 s. This technique was considered for application to the Square Kilometre Array SKA1-low radio telescope.