Precision timing and Rf signal dissemination for XFEL by delivering optical frequency comb through length-stabilized fiber

We have developed the precision timing and rf signal dissemination system for the X-ray free electron laser (XFEL), under construction in Japan. The optical frequency comb was transmitted through a 1-km length-stabilized optical fiber for disseminating both rf and timing signals. The phase fluctuations of the rf signals at 5.712 GHz was suppressed down to 0.0042 radian that is used for synchronizing linear accelerators, and the timing jitter between optical pulses are suppressed down to 50 fs that is used for providing X-ray trigger timing to the users, both of which satisfy the requirement of the XFEL.