[1] [1] Calonico D, Bertacco E K, Calosso C E, et al. High-accuracy coherent optical frequency transfer over a doubled 642 km fiber link[J]. Applied Physics B, 2014, 117(3): 979-986.

[2] [2] Kim J, Cox J A, Chen J, et al. Drift-free femtosecond timing synchronization of the remote optical and microwave sources[J]. Nature Photonics, 2008, 2(12): 733-736.

[3] [3] Droste S, Ozimek F, Udem T, et al. Optical frequency transfer via 1840 km fiber link with superior stability. frequency control symposium[C]//IEEE Cleo: Science & Innovations, 2014.

[4] [4] Krehlik P, Schnatz H, Sliwczynski L. A hybrid solution for simultaneous transfer of ultrastable optical frequency, RF frequency, and UTC time-tags over optical fiber[J]. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2017, 64(12): 1884-1890.

[5] [5] Fuyu S, Dong H, Danian Z, et al. Femtosecond-level timing fluctuation suppression in atmospheric frequency transfer with passive phase conjunction correction[J]. Optics Express, 2017, 25(18): 21312-21320.

[6] [6] Sprenger B, Zhang J, Lu Z H, et al. Atmospheric transfer of optical and radio frequency clock signals[J]. Optics Letters, 2009, 34(7): 965-967.

[7] [7] Gozzard D R, Schediwy S W, Stone B, et al. Stabilized free-space optical frequency transfer[J]. Physical Review Applied, 2018, 10(2): 024-046.

[8] [8] Giorgetta F R, Swann W C, Sinclair L C, et al. Optical two-way time and frequency transfer over free space[J]. Nature Photonics, 2013, 7(6): 434-438.

[9] [9] Sinclair L C, Swann W C, Bergeron H, et al. Synchronization of clocks through 12 km of strongly turbulent air over a city[J]. Applied Physics Letters, 2016, 109(15): 151104.

[10] [10] Sinclair L C, Bergeron H, Swann W C, et al. Comparing optical oscillators across the air to milliradians in phase and 10-17 in frequency[J]. Physical Review Letters, 2017, 120(5): 171-175.

[11] [11] Deschenes J D, Sinclair L C, Giorgetta F R, et al. Synchronization of distant optical clocks at the femtosecond level[J]. Physical Review X, 2015, 6(2): 519-530.

[12] [12] Yu W, Shaif-Ul A, D E O, et al. Generation of stretched pulses and dissipative solitons at 2 m from an all-fiber mode-locked laser using carbon nanotube saturable absorbers[J]. Optics letters, 2016, 41(16): 3864-3867.

[13] [13] Frithjof H, Dieter W, Uwe M, et al. Monotonically chirped pulse evolution in an ultrashort pulse thulium-doped fiber laser[J]. Optics letters, 2012, 37(6): 1014-1016.

[14] [14] Sinclair L C, Bergeron H, Swann W C, et al. Femtosecond optical two-way time-frequency transfer in the presence of motion[J]. Physical Review A, 2019, 99(2): 023844.