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Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2017, Vol. 28 ›› Issue (4): 57 doi: 10.1007/s41365-017-0205-z


Laser–RF synchronization based on digital phase detector

Jin Yang1,2, Ying-Chao Du1,2, Li-Xin Yan1,2, Gang Huang3, Qiang Du3, Yi-Lun Xu1,2,3, Wen-Hui Huang1,2, Huai-Bi Chen1,2   

  1. 1 Department of Engineering Physics, Tsinghua University, Beijing 100084, China
    2 Key Laboratory of Particle and Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084, China
    3 Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
  • Supported by:

    Supported by the China Scholarship Council.

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Jin Yang, Ying-Chao Du, Li-Xin Yan, Gang Huang, Qiang Du, Yi-Lun Xu, Wen-Hui Huang, Huai-Bi Chen. Laser–RF synchronization based on digital phase detector.Nuclear Science and Techniques, 2017, 28(4): 57     doi: 10.1007/s41365-017-0205-z


Laser oscillator synchronization with RF reference signal is ultra-important for a modern light source based on the accelerator. For Tsinghua Thomson scattering X-ray source, we have synchronized the mode-locked laser oscillator to RF reference signal with 48.2 fs RMS relative jitter. Both fundamental and harmonic signals derived from photo diode detection are used for laser–RF synchronization in our scheme. The fundamental signal is for coarse laser–RF synchronization and multiple laser oscillator synchronization. The harmonic signal is for high precise phase locking. The digital phase detector is implemented in the synchronization scheme for less noise, replacing the mixing to DC phase detection scheme. The digital processing algorithm for synchronization is commonly used in low-level RF control field. In order to test the phase locking loop logic without damaging the real laser oscillator, a laser oscillator emulator was developed for phase locking. This paper will report the laser–RF synchronization scheme and its performance. The laser oscillator emulator system will also be introduced here.

Key words: Laser oscillator, Synchronization, ')">RF, LLRF')">LLRF, Emulator