Coherent Optical Frequency Transfer via a 490 km Noisy Fiber Link

• 作者: Xiang Zhang Xue Deng Qi Zang Dongdong Jiao Jing Gao Dan Wang Qian Zhou Jie Liu Guanjun Xu Ruifang Dong Tao Liu Shougang Zhang
• 来源期刊: 中国物理快报（英文版）
• 年，卷（期）: 2022,（4）
• 所属期刊栏目: FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS)
• 页码范围: 7-11
• 页数: 5页
• 语种: 英文
• DOI: 10.1088/0256-307X/39/4/044201

摘要

We demonstrate the coherent transfer of an ultrastable optical frequency reference over a 490 km noisy field fiber link.The fiber-induced phase noise power spectrum density per-unit-length at 1 Hz offset frequency can reach up to 510 rad2·Hz-1·km-1,which is much higher than the fiber noise observed in previous reports.This extreme level of phase noise is mainly due to the fiber link laying underground along the highway.Appropriate phase-locked loop parameters are chosen to complete the active compensation of fiber noise by measuring the intensity fluctuation of additional phase noise and designing a homemade digital frequency division phase discriminator with a large phase detection range of 2127rrad.Finally,a noise suppression intensity of approximately 40 dB at 1Hz is obtained,with fractional frequency instability of 1.1×10-14 at 1s averaging time,and 3.7×10-19 at 10000 s.The transfer system will be used for remote atomic clock comparisons and optical frequency distribution over a long-distance communication network established in China.