[1] Ahmed H Zewail. Femtochemistry: atomic-scale dynamics of the chemical bond[J]. The Journal of Physical Chemistry A, 104, 5660-5694(2000).

[2] Xin Zhu, Christine L Kalcic, Nelson Winkler. Applications of femtochemistry to proteomic and metabolomic analysis[J]. The Journal of Physical Chemistry A, 114, 10380-10387(2010).

[3] Hrvoje Petek. Single-molecule femtochemistry: molecular imaging at the space-time limit[J]. Acs Nano, 8, 5-13(2014).

[4] Ulf Saalmann, Jan-Michael Rost. Ionization of clusters in intense laser pulses through collective electron dynamics[J]. Physical Review Letters, 91, 223401(2003).

[5] Psikal J, Tikhonchuk V T, Limpouch J. Ion acceleration by femtosecond laser pulses in small multispecies targets[J]. Physics of Plasmas, 15, 053102(2008).

[6] Rafael R Gattass, Eric Mazur. Femtosecond laser micromachining in transparent materials[J]. Nature Photonics, 2, 219-225(2008).

[7] Anatol Khilo, Steven J Spector, Matthew E Grein. Photonic ADC: overcoming the bottleneck of electronic jitter[J]. Optics Express, 20, 4454-4469(2012).

[8] Schulz S, Grguras I, Behrens C. Femtosecond all-optical synchronization of an X-ray free-electron laser[J]. Nature Communication, 6, 5938(2015).

[9] Matthew Walbran, Alexander Gliserin, Kwangyun Jung. 5-femtosecond laserelectron synchronization for pump-probe crystallography and diffraction[J]. Physical Review Applied, 4, 044013(2015).

[10] Bartels A, Diddams S A, Oates C W. Femtosecond-laser-based synthesis of ultrastable microwave signals from optical frequency references[J]. Optics Letters, 30, 667-669(2005).

[11] Cox J A, Putnam W P, Sell A. Pulse synthesis in the single-cycle regime from independent mode-locked lasers using attosecond-precision feedback[J]. Optics Letters, 37, 3579-3581(2012).

[12] Paolo Ghelfi, Francesco Laghezza, Filippo Scotti. A fully photonics-based coherent radar system[J]. Nature, 507, 341-345(2014).

[13] Ming Xin, Kemal Şafak, Franz X Kärtner. Ultra-precise timing and synchronization for large-scale scientific instruments[J]. Optica, 5, 1564-1578(2018).

[14] Kim J, Kärtner F X. Attosecond-precision ultrafast photonics[J]. Laser and Photonics Reviews, 4, 432-456(2010).

[15] [15] Donald Barrett Sullivan, David W Allan, David A Howe, et al.. acterization of Clocks Oscillats [M]. US: Department of Commerce, National Institute of Stards Technology, 1990.

[16] [16] Montress G K, Parker T E, Loboda M J. Residual phase noise measurements of VHF, UHF, microwave components [C]Proceedings of the 43rd Annual Symposium on IEEE, 1989, 41(5): 664679.

[17] D vonder Linde. Characterization of the noise in continuously operating mode-locked lasers[J]. Applied Physics B, 39, 201-217(1986).

[18] Ouyang Chunmei, Shum Ping, Wang Honghai. Observation of timing jitter reduction induced by spectral filtering in a fiber laser mode locked with a carbon nanotube-based saturable absorber[J]. Optics Letters, 35, 2320-2322(2010).

[19] [19] Scott R P, Langrock C, Kolner B H. Highdynamicrange laser amplitude phase noise measurement techniques [C] IEEE Journal of ed Topics in Quantum Electronics, 2001, 7(4): 641655.

[20] Youjian Song, Chur Kim, Kwangyun Jung. Timing jitter optimization of mode-locked Yb-fiber lasers toward the attosecond regime[J]. Optics Express, 19, 14518-14525(2011).

[21] Xu Shaofu, Zou Xiuting, Ma Bowen. Deep-learning-powered photonic analog-to-digital conversion[J]. Light: Science & Applications, 8, 66(2019).

[22] Andrew J Benedick, James G Fujimoto, Franz X. Kartner. Optical flywheels with attosecond jitter[J]. Nature Photonics, 6, 97-100(2012).

[23] Peng Qin, Youjian Song, Hyoji Kim. Reduction of timing jitter and intensity noise in normal-dispersion passively mode-locked fiber lasers by narrow band-pass filtering[J]. Optics Express, 22, 28276-28283(2014).

[24] Wei Chen, Youjian Song, Kwangyun Jung. Few-femtosecond timing jitter from a picosecond all-polarization-maintaining Yb-fiber laser[J]. Optics Express, 24, 1347-1357(2016).

[25] Hou D, Lee C-C, Yang Z. Timing jitter characterization of mode-locked lasers with <1 zs/√Hz resolution using a simple optical heterodyne technique[J]. Optics Letters, 40, 2985-2988(2015).

[26] Tae Keun Kim, Youjian Song, Kwangyun Jung. Sub-100-as timing jitter optical pulse trains from mode-locked Er-fiber lasers[J]. Optics Letters, 36, 4443-4445(2011).

[27] Kwangyun Jung, Jungwon Kim. All-fibre photonic signal generator for attosecond timing and ultralow-noise microwave[J]. Scientific Reports, 5, 16250(2015).

[28] Tian Haochen, Yang Wenkai, Dohyeon Kwon. Optical frequency comb noise spectra analysis using an asymmetric fiber delay line interferometer[J]. Optics Express, 28, 9232-9243(2020).

[29] Bartels A, Cerna R, Kistner C. Ultrafast time-domain spectroscopy based on high-speed asynchronous optical sampling[J]. Review of Scientific Instruments, 78, 035107(2007).

[30] Shi Haosen, Song Youjian, Yu JiaHe. Quantum-limited timing jitter characterization of mode-locked lasers by asynchronous optical sampling[J]. Optics Express, 25, 10-19(2017).

[31] Li Duo, Umit Demirbas, Andrew Benedick. Attosecond timing jitter pulse trains from semiconductor saturable absorber mode-locked Cr:LiSAF lasers[J]. Optics Express, 20, 23422-23435(2012).

[32] Portuondo-Campa E, Paschotta R, Lecomte S. Sub-100 attosecond timing jitter from low-noise passively mode-locked solid-state laser at telecom wavelength[J]. Optics Letters, 38, 2650-2653(2013).

[33] Jungwon Kim, Jeff Chen, Jonathan Cox. Attosecond-resolution timing jitter characterization of free-running mode-locked lasers[J]. Optics Letters, 32, 3519-3521(2007).

[34] Kuse N, Jiang J, Lee C-C. All polarization-maintaining Er fiber-based optical frequency combs with nonlinear amplifying loop mirror[J]. Optics Express, 24, 3095-3102(2016).

[35] Jian Chen, Jason W Sickler, Peter Fendel. Generation of low-timing-jitter femtosecond pulse trains with 2 GHz repetition rate via external repetition rate multiplication[J]. Optics Letters, 33, 959-961(2008).

[36] Heewon Yang, Hyoji Kim, Junho Shin. Gigahertz repetition rate, sub-femtosecond timing jitter optical pulse train directly generated from a mode-locked Yb:KYW laser[J]. Optics Letters, 39, 56-59(2014).

[37] Wang Yan, Tian Haochen, Ma Yuxuan. Timing jitter of high-repetition-rate mode-locked fiber lasers[J]. Optics Letters, 43, 4382-4385(2018).

[38] Wang Yan, Tian Haochen, Hou Dong. Timing jitter reduction through relative intensity noise suppression in high-repetition-rate mode-locked fiber lasers[J]. Optics Express, 27, 11273-11280(2019).

[39] Jiazheng Song, Hushan Wang, Xinning Huang. Compact low-noise passively mode-locked Er-doped femtosecond all-fiber laser with 2.68 GHz fundamental repetition rate[J]. Applied Optics, 58, 1733-1738(2019).

[40] Lianping Hou, Mohsin Haji, Jehan Akbar. Low divergence angle and low jitter 40 GHz AlGaInAs/InP 1.55 μm mode-locked lasers[J]. Optics Letters, 36, 966-968(2011).

[41] Haroon Asghar, Wei Wei, Pramod Kumar. Stabilization of self-mode-locked quantum dash lasers by symmetric dual-loop optical feedback[J]. Optics Express, 26, 4581-4592(2018).

[42] Liu Songtao, Tin Komljenovic, Sudharsanan Srinivasan. Characterization of a fully integrated heterogeneous silicon/III-V colliding pulse mode-locked laser with on-chip feedback[J]. Optics Express, 26, 9714-9723(2018).

[43] Dongin Jeong, Dohyeon Kwon, Igju Jeon. Ultralow jitter silica microcomb[J]. Optica, 7, 1108-1111(2020).

[44] Pang M, He W, Jiang X. All-optical bit storage in a fibre laser by optomechanically bound states of solitons[J]. Nature Photonics, 10, 454-458(2016).

[45] Shi Haosen, Song Youjian, Wang Chingyue. Observation of subfemtosecond fluctuations of the pulse separation in a soliton molecule[J]. Optics Letters, 43, 1623-1626(2018).

[46] Kim Jungwon, Song Youjian. Ultralow-noise mode-locked fiber lasers and frequency combs: principles, status, and applications[J]. Advances in Optics and Photonics, 8, 465-540(2016).

[47] Jian Chen, Jason W Sickler, Erich P Ippen. High repetition rate, low jitter, low intensity noise, fundamentally mode-locked 167 fs soliton Er-fiber laser[J]. Optics Letters, 32, 1566-1568(2007).

[48] [48] Jian Chen, Jason Sickler, Hyunil Byun, et al. Fundamentally modelocked 3 GHz femtosecond erbium fiber laser [C] Ultrafast Phenomena XVI: Proceedings of the 16th International Conference, 2009: 732–734.

[49] [49] Li Xing, Zou Weiwen, Wu Kan, et al., Timingjitter reduction by use of a spectral filter in a broadb femtosecond fiber laser [C]IEEE Photonics Technology Letters, 2010,27(8): 911914.

[50] Hyunil Byun, Michelle Y Sander, Ali Motamedi. Compact, stable 1 GHz femtosecond Er-doped fiber lasers[J]. Applied Optics, 49, 5577-5582(2010).

[51] Chur Kim, Sangho Bae, Khanh Kieu. Sub-femtosecond timing jitter, all-fiber, CNT-mode-locked Er-laser at telecom wavelength[J]. Optics Express, 21, 26533-26541(2013).

[52] Kan Wu, Xiaoyan Zhang, Jun Wang. 463-MHz fundamental mode-locked fiber laser based on few-layer MoS₂ saturable absorber[J]. Optics Letters, 40, 1374-1377(2015).

[53] Kwangyun Jung, Jungwon Kim. Characterization of timing jitter spectra in free-running mode-locked lasers with 340 dB dynamic range over 10 decades of Fourier frequency[J]. Optics Letters, 40, 316-319(2015).

[54] Junho Shin, Kwangyun Jung, Youjian Song. Characterization and analysis of timing jitter in normal-dispersion mode-locked Er-fiber lasers with intra-cavity filtering[J]. Optics Express, 23, 22898-22906(2015).

[55] Dohyun Kim, Dohyeon Kwon, Bongwan Lee. Polarization-maintaining nonlinear-amplifying-loop-mirror mode-locked fiber laser based on a 3 × 3 coupler[J]. Optics Letters, 44, 1068-1071(2019).

[56] Bao Chengying, Yang Changxi. Harmonic mode-locking in a Tm-doped fiber laser: characterization of its timing jitter and ultralong starting dynamics[J]. Optics Communications, 356, 463-467(2015).

[57] [57] Ahmet E Akosman, Michelle Y Ser. Low noise, modelocked 253 MHz TmHo fiber laser with ce pumping at 790 nm [C]IEEE Photonics Technology Letters, 2016, 28(17): 18781881.

[58] Cheng Huihui, Wang Wenlong, Zhou Yi. High-repetition-rate ultrafast fiber lasers[J]. Optics Express, 26, 16411-16421(2018).

[59] Kristina Bagnell, Anthony Klee, Peter J Delfyett. Demonstration of a highly stable 10 GHz optical frequency comb with low timing jitter from a SCOWA-based harmonically mode-locked nested cavity laser[J]. Optics Letters, 43, 2396-2399(2018).

[60] Emma P, Akre R, Arthur J. First lasing and operation of an ångstrom-wavelength free-electron laser[J]. Nature Photonics, 4, 641-647(2010).

[61] Altarelli M. The European X-ray free-electron laser facility in Hamburg[J]. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 269, 2845-2849(2011).

[62] Christopher J Milne. Thomas Schietinger, Masamitsu Aiba. The Swiss X-ray free electron laser[J]. Applied Sciences, 7, 720(2017).

[63] Huang Zhirong, Ingolf Lindau. SACLA hard-X-ray compact FEL[J]. Nature Photonics, 6, 505-506(2012).

[64] Zhao Zhentang, Wang Dong, Gu Qiang. SXFEL: a soft X-ray free electron laser in China[J]. Synchrotron Radiation News, 3, 29-33(2017).

[65] Zhao Zhentang, Wang Dong, Yin Lixin. Shanghai soft X-ray freeelectron laser facility[J]. Chinese Journal of Lasers, 46, 0100004(2019).

[66] Eduard Prat, Sven Reiche. Simple method to generate terawatt-attosecond X-ray free-electron-laser pulses[J]. Physical Review Letters, 114, 244801(2015).

[67] Calegari F, Ayuso D, Trabattoni A. Ultrafast electron dynamics in phenylalanine initiated by attosecond pulses[J]. Science, 346, 336-339(2014).

[68] Öström H, Öberg H, Xin H. Probing the transition state region in catalytic CO oxidation on Ru[J]. Science, 347, 978-982(2015).

[69] [69] Şafak K, Cheng H P H, Dai A, et al. Singlemode fiber based pulsedoptical timing link with fewfemtosecond precision in SwissFEL [C]Conference on Lasers ElectroOptics, 2019: JTh2A.100.

[70] Ming Xin, Kemal Şafak, Michael Y Peng. One-femtosecond, long-term stable remote laser synchronization over a 3.5-km fiber link[J]. Optics Express, 22, 14904-14912(2014).

[71] George C Valley. Photonic analog-to-digital converters[J]. Optics Express, 15, 1955-1982(2007).

[72] Jungwon Kim, Matthew J Park, Michael H Perrott. Photonic subsampling analog-to-digital conversion of microwave signals at 40-GHz with higher than 7-ENOB resolution[J]. Optics Express, 16, 16509-16515(2008).

[73] Jonghan Jin. Dimensional metrology using the optical comb of a mode-locked laser[J]. Measurement Science and Technology, 27, 022001(2016).

[74] Coddington I, Swann W C, Nenadovic L. Rapid and precise absolute distance measurements at long range[J]. Nature Photonics, 3, 351-356(2009).

[75] Zhang Hongyuan, Wei Haoyun, Wu Xuejian. Absolute distance measurement by dual-comb nonlinear asynchronous optical sampling[J]. Optics Express, 22, 6597-6604(2014).

[76] Shi Haosen, Song Youjian, Liang Fei. Effect of timing jitter on time-of-flight distance measurements using dual femtosecond lasers[J]. Optics Express, 23, 14057-14069(2015).

[77] Ma Yanxing, Wang Xiaolin, Leng Jinyong. Coherent beam combination of 1.08 kW fiber amplifier array using single frequency dithering technique[J]. Optics Letters, 36, 951-953(2011).

[78] Liu Zejin, Ma Pengfei, Su Rongtao. High-power coherent beam polarization combination of fiber lasers: progress and prospect [Invited][J]. Journal of the Optical Society of America B, 34, A7-A14(2017).

[79] Robert K Shelton, Long-Sheng Ma, Henry C Kapteyn. Phase-coherent optical pulse synthesis from separate femtosecond lasers[J]. Science, 17, 1286-1289(2001).

[80] Cristian Manzoni, Oliver D Mücke, Giovanni Cirmi. Coherent pulse synthesis: towards sub‐cycle optical waveforms[J]. Laser & Photonics Reviews, 9, 129-171(2012).

[81] Cox J A, Putnam W P, Sell A. Pulse synthesis in the single-cycle regime from independent mode-locked lasers using attosecond-precision feedback[J]. Optical Letters, 37, 3579-3581(2012).

[82] Tian Haochen, Song Youjian, Meng Fei. Long-term stable coherent beam combination of independent femtosecond Yb-fiber lasers[J]. Optical Letters, 41, 5142-5145(2016).

[83] Ge Aichen, Liu Bowen, Chen Wei. Generation of few-cycle laser pulses by coherent synthesis based on a femtosecond Yb-doped fiber laser amplification system[J]. Chinese Optics Letters, 17, 041403(2019).

[84] Trocha P, Karpov M, Ganin D. Ultrafast optical ranging using microresonator soliton frequency combs[J]. Science, 359, 887-891(2018).

[85] Myoung-Gyun Suh, Kerry J Vahala. Soliton microcomb range measurement[J]. Science, 359, 884-887(2018).