[2] HEAVNER T P,DONLEY E A,LEVI F,et al. First accuracy evaluation of NIST-F2[J]. Metrologia, 2014(51):174-182.

[3] NICHOLSON T L,CAMPBELL S L,HUTSON R B,et al. Systematic evaluation of an atomic clock at 2×10-18 total uncertainty[J].Nature Communications, 2015(6):6896.

[4] MCGREW W F, ZHANG X, FASANO R J, et al. Atomic clock performance enabling geodesy below the centimetre level[J].Nature, 2018(564):87-90.

[7] KANG J,SHIN J,KIM C,et al. Few-femtosecond resolution characterizatioin and suppression of excess timing jitter and drift in indoor atmosphere frequency comb transfer[J]. Optics Express, 2014,22(21):26023-26031.

[13] HARTOG A H, CONDUIT A J, PAYNE D N. Variation of pulse delay with stress and temperature in jacketed and unjacketed optical fibres[J]. Optical and Quantum Electronics, 1979(11):265-273.