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Chinese Optics Letters, Vol. 17, Issue 7, 071407 (2019)

All-fiber-based laser with 200  mHz linewidth

Junchao Huang1,2, Lingke Wang1,2, Yifei Duan1,2, Yafeng Huang1,2, Meifeng Ye1, Liang Liu1, and Tang Li1,*

Author Affiliations

  • 1Key Laboratory of Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
  • 2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China


We demonstrate the frequency stabilization of a 1.55 μm erbium-doped fiber laser by locking it to a 5-km-long optical fiber delay line (FDL). The stabilized laser is characterized via comparison with a second identical laser system. We obtain a fractional frequency stability of better than 3 × 10−15 over time scales of 1–10 s and a laser linewidth of 0.2 Hz, which is the narrowest linewidth of an FDL-stabilized laser observed to date.