Absolute phase synchronization over optical fiber

An absolute phase synchronization method based on phase-conjugation scheme is demonstrated. A repeatable phase difference regardless of restart operation and fiber route changing between the phase standard at local site and the recovered signal at the intermediate-access node is achieved. This indicates that absolute phase synchronization to arbitrary nodes along the fiber link is feasible. At the intermediate-access node, this phase difference is highly stable with a fluctuation of ±0.014 rad over 10000s. And this phase difference shows consistency within 2% of the full cycle under different situations such as restart operation and fiber route changing.