面向XFEL的公里级光纤链路的飞秒精度时钟分布

IWe demonstrated a fiber link based timing distribution with femtosecond precision. The output femtosecond laser pulse train from a passively mode-locked fiber laser serves as master clock, which is distributed over a 2 kilometer single mode fiber link. A balanced optical cross-correlator (BOC) is used to monitor the accumulated timing error, which is actively compensated by a local fiber stretcher and a step motor. The standard deviation of the residual timing error is less than 1.1 fs over 2 hours observation, and the time stability is better than 10-18.