Progress in Large-Scale Femtosecond Timing Distribution and RF-Synchronization

Fourth-generation Light sources such as the European X-Ray free electron laser facility (XFEL), the Linear Coherent Light Source at SLAC (LCLS) as well as the ELLETRA-Facility at Trieste require femtosecond synchronization between low-level RF-systems, photo-injector laser, as well as potential probe lasers in these facilities. We recently proposed a modular system that is capable of achieving synchronization of various RF-and optical sub-systems with femtosecond precision over distances of a few kilometers [1], the typical size of the proposed facilities. In this paper, we report on recent progress towards the realization of such a system. Especially the construction of a low jitter optical master oscillator that generates the optical pulse stream that is necessary to stabilize the fiber transmission links of such a system and simultaneously carriers the timing information to the individual optical and RF sub-systems.