Stable Transmission of RF Signals With Low-Delay Passive Method Over Fiber Link

In this letter, we propose a low-delay passive compensation system for stable radio frequency (RF) transmission over fiber links. Different from previous technology, the proposed structure requires only two trips of transmission, decreasing compensation delay and enhancing synchronization performance. The method utilizes a mixer to implement phase conjugation and compensation for the phase fluctuation in the communication link and a phase-locked loop (PLL) is added to the remote end to reduce the loop bandwidth, enhancing the transmission distance. Real-world experiments conducted over a 64.4 km metropolitan area network (MAN) link in Beijing demonstrated the system's capability to transmit stable RF signals.