XFEL飞秒同步与定时系统中光纤长度变化的数字化监测(英)

分析了X射线自由电子激光装置对飞秒同步定时系统的技术需求。系统中采用光纤来传输定时/相位信息。而光纤的光长度会随温度的慢漂而改变，因此通过对比实验研究了温度慢漂对光纤长度变化的影响。研制了基于现场可编程门阵列（FPGA）的数字化相位和幅度检测器对光纤长度变化进行数据监测。百米光纤在典型昼夜温差下导致的时间延迟约6 ps。结果显示此数字化相位和幅度检测器可以用于飞秒同步定时系统的长度变化监测和稳定控制系统当中。

Digital monitoring for length variation of optical fibers in femtosecond timing and synchronization system of XFEL

Digital monitoring for length variation of optical fibers in femtosecond timing and synchronization system of XFEL The requirements for the femtosecond timing and synchronization (fs TS) system in an X-ray free electron laser (XFEL) facility are analyzed. The timing/phase distribution method using optical fiber is adopted. Since the optical length of the fiber changes as the temperature drifts, the influence of temperature drift on the length variation of the fiber is studied in comparative experiments. An FPGA-based digital phase/amplitude detector is designed to record the data of the length variation. For a 100-meter-long fiber, the timing drift caused by length variation is 6 ps (peak-peak value) over 24 hours. The result shows the digital phase/amplitude detector could be used for length variation monitoring and stabilization of the fs TS system.