New Method for Cascaded Fiber-Optic Radio Frequency Transfer

We report on a new method for cascaded long-haul fiber-optic radio frequency (RF) transfer. The phase noise compensation device is placed at the relay site to simultaneously compensate for phase noise coming from the front and the second segment fibers. At the same time, the technique can have the capability to share the modulated optical signal for the both links, simplifying the configuration at the relay site. This scheme not only greatly simplifies the cascaded RF transfer system but also effectively improves the system noise floor. Experimentally, we demonstrated a 1 GHz signal transfer over a 210 km (100+110 km) fiber-optic link, achieving the fractional frequency stability less than 2.3 × 10
^−
14
at 1 s and 5.4 × 10
⁻¹⁷
at 10,000 s.