Author: Callahan, P.T.
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MOP042 All-Fiber Approach to Long-Term Stable Timing Distribution System 122
  • M. Xin, K. Safak, F.X. Kaernter
    DESY, Hamburg, Germany
  • P.T. Callahan, M.Y. Peng
    MIT, Cambridge, Massachusetts, USA
  High precision timing distribution systems are critical for free-electron lasers (FELs). Real facilities such as FLASH and the European XFEL need fiber networks consisting of 20 or more timing links, which require tremendous attention to the alignment and stability of the free-space optics to minimize timing-drifts induced by beam pointing instabilities. This situation also necessitates preamplification of the master laser output to overcome excessive free-space to fiber coupling losses to provide adequate power for all timing links. Recently, we have developed integrated, fiber-coupled balanced optical cross-correlators (FC-BOC) using periodically-poled KTiOPO4 (PPKTP) waveguides. These waveguides exhibit second harmonic conversion efficiencies 20 times higher than the bulk optical devices, which will decrease the power demand from the master laser and consequently support more timing links. Furthermore, the robustness and ease of implementation of these fiber-coupled devices will eliminate alignment-related problems observed in free-space optics. In this paper, we present an all-fiber implementation of a 3.5-km timing distribution system using FC-BOCs, over 200 hours operation without interruption. The remaining drift (<1 Hz) is only 3.3 fs RMS, and the integrated jitter above 1 Hz is kept below 0.7 fs, which is more than sufficient for an efficient FEL synchronization.  
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