Stabilized microwave-frequency transfer using optical phase sensing and actuation

We present a stabilized microwave-frequency transfer technique that is based on optical phase sensing and optical phase actuation. This technique shares several attributes with optical-frequency transfer and, therefore, exhibits several advantages over other microwave-frequency transfer techniques. We demonstrated the stabilized transfer of an 8000 MHz microwave-frequency signal over a 166 km metropolitan optical fiber network, achieving a fractional frequency stability of 6.8 × 10−14 Hz∕Hz at 1 s integration and 5.0 × 10−16 Hz∕Hz at 1.6 × 104 s. This technique is being considered for use on the Square Kilometre Array SKA1-mid radio telescope.