[1] Shi Wei, Fang Qiang, Zhu Xiushan. Fiber lasers and their applications[J]. Applied Optics, 53, 6554-6558(2014).

[2] [2] Qu Zhou, Li Qiushi, Meng Hailong, et al. Application the key technology on highpower fiberoptic laser in laser weapon[C]Proc of SPIE. 2014: 92940C.

[3] [3] Naeem M. Advances in drilling with fiber lasers[C]Industrial Laser Applications Symposium. 2015.

[4] Tony H. Laser marking with fiber lasers[J]. Industrial Laser Solutions, 27, 7(2012).

[5] [5] Clery D. Laser fusion, with a difference [J]. Science, 2015, 347(6218):111112.

[6] Zervas M N, Codemard C A. High power fiber lasers: a review[J]. IEEE Journal of Selected Topics in Quantum Electronics, 20, 219-241(2014).

[7] [7] Shiner B. The impact of fiber laser technology on the wld wide material processing market[C]Conference on Lasers ElectroOptics. 2013.

[8] Lin Honghuan, Xu Lixin, Li Chengyu. 10.6 kW high-brightness cascade-end-pumped monolithic fiber lasers directly pumped by laser diodes in step-index large mode area double cladding fiber[J]. Results in Physics, 14, 102479(2019).

[9] [9] Lin Aoxiang, Zhan Huan, Peng Kun, et al. 10 kWlevel pumpgain integrated functional laser fiber[C]Asia Communications Photonics Conference. 2018.

[10] Dawson J W, Messerly M J, Beach R J. Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power[J]. Optics Express, 16, 13240-13266(2008).

[11] Zhu Jiajian, Zhou Pu, Ma Yanxing. Power scaling analysis of tandem-pumped Yb-doped fiber lasers and amplifiers[J]. Optics Express, 19, 18645-18654(2011).

[12] [12] Otto H J, Jauregui C, Limpert J, et al. Average power limit of fiberlaser systems with nearly diffractionlimited beam quality[C]Proc of SPIE. 2016:97280E.

[13] Liu Zejin, Zhou Pu, Xu Xiaojun. Coherent beam combining of high power fiber lasers: Progress and prospect[J]. Science China (Technological Sciences), 56, 1597-1606(2013).

[14] [14] Madasamy P, Thomas A, Loftus T, et al. Comparison of spectral beam combining approaches f high power fiber laser systems[C]Proc of SPIE. 2008: 695207.

[17] [17] Tian Fei, Yan Hong, Chen Li, et al. Investigation on the influence of spectral linewidth broadening on beam quality in spectral beam combination[C]Proc of SPIE. 2015:92553N.

[18] [18] Duk E, Lu W, Akbulut M, et al. 1 kW CW Ybfiberamplifier with＜0.5 GHz linewidth neardiffraction limited beamquality f coherent combining application[C]Proc of SPIE. 2011: 791407.

[19] Beier F, Hupel C, Nold J. Narrow linewidth, single mode 3 kW average power from a directly diode pumped ytterbium-doped low NA fiber amplifier[J]. Optics Express, 24, 6011-6020(2016).

[20] Liem A, Tünnermann A, Sattler B. Single mode 4.3 kW output power from a diode-pumped Yb-doped fiber amplifier[J]. Optics Express, 25, 14892-14899(2017).

[21] Yu C X, Shatrovoy O, Fan T Y. Diode-pumped narrow linewidth multi-kilowatt metalized Yb fiber amplifier[J]. Optics Letters, 41, 5202-5205(2016).

[23] Ran Yang, Tao Rumao, Ma Pengfei. 560 W all fiber and polarization-maintaining amplifier with narrow linewidth and near-diffraction-limited beam quality[J]. Applied Optics, 54, 7258-7263(2015).

[25] Naderi N A, Flores A, Anderson B M. Beam combinable, kilowatt, all-fiber amplifier based on phase-modulated laser gain competition[J]. Optics Letters, 41, 3964-3967(2016).

[26] [26] Dajani I, Fles A, Ehrenreich T. Multikilowatt power scaling coherent beam combining of narrowlinewidth fiber lasers [C]Proc fo SPIE. 2016: 972801.

[27] Flores A, Robin C, Lanari A. Pseudo-random binary sequence phase modulation for narrow linewidth, kilowatt, monolithic fiber amplifiers[J]. Optics Express, 22, 17735-17744(2014).

[28] Jun C, Jung M, Shin W. 818 W Yb-doped amplifier with < 7 GHz linewidth based on pseudo-random phase modulation in polarization-maintained all-fiber configuration[J]. Laser Physics Letters, 16, 015102(2019).

[29] Liu Meizhong, Yang Yifeng, Shen Hui. 1.27 kW, 2.2 GHz pseudo random binary sequence phase modulated fiber amplifier with Brillouin gain spectrum overlap[J]. Scientific Reports, 10, 629(2020).

[30] Huang Zhihua, Liang Xiaobao, Li Chengyu. Spectral broadening in high-power Yb-doped fiber lasers employing narrow-linewidth multilongitudinal-mode oscillators[J]. Applied Optics, 55, 297-302(2016).

[31] Huang Yusheng, Yan Ping, Wang Zehui. 2.19 kW narrow linewidth FBG-based MOPA configuration fiber laser[J]. Optics Express, 27, 3136-3145(2019).

[32] Junsu L, Kwang H L, Hwanseong J. 2.05 kW all-fiber high-beam-quality fiber amplifier with stimulated Brillouin scattering suppression incorporating a narrow-linewidth fiber-Bragg-grating-stabilized laser diode seed source[J]. Applied Optics, 58, 6251-6256(2019).

[34] [34] Platonov N, Yagodkin R, Cruz J, et al. 1.5 kW linear polarized on PM fiber 2 kW on nonPM fiber narrow linewidth CW diffractionlimited fiber amplifier [C]Proc of SPIE. 2017: 100850M.

[35] [35] Nikolai P, Roman Y, Joel D L C, et al. Up to 2.5 kW on nonPM fiber 2.0 kW linear polarized on PM fiber narrow linewidth CW diffractionlimited fiber amplifiers in allfiber fmat[C]Proc of SPIE. 2018: 105120E.

[36] [36] Kanskar M, Zhang J, Kaponen J, et al. Narrowb transversemodalinstability (TMI)free Ybdoped fiber amplifiers f directed energy applications[C]Proc of SPIE. 2018: 2291253.

[37] Ma Pengfei, Tao Rumao, Su Rongtao. 1.89 kW all-fiberized and polarization-maintained amplifiers with narrow linewidth and near-diffraction-limited beam quality[J]. Optics Express, 24, 4187-4195(2016).

[38] Su Rongtao, Tao Rumao, Wang Xiaolin. 2.43 kW narrow linewidth linearly polarized all-fiber amplifier based on mode instability suppression[J]. Laser Physics Letters, 14, 085102(2017).

[39] [39] Qi Yunfeng, Lei Ming, Liu Chi, et al. 1.75 kW CW narrow linewidth Ybdoped allfiber amplifiers f beam combining application[C]Conference on Lasers ElectroOptics. 2015: ATu4M.4.

[40] [40] Qi Yunfeng, Yang Yifeng, Shen Hui, et al. 2.7 kW CW narrow linewidth Ybdoped allfiber amplifiers f beam combining application [C]Advanced SolidState Lasers. 2017: ATu3A.1.

[41] Li Tenglong, Zha Congwen, Sun Yinhong. 3.5 kW bidirectionally pumped narrow-linewidth fiber amplifier seeded by white-noise-source phase-modulated laser[J]. Laser Physics, 28, 105101(2018).

[42] Chang Zhe, Wang Yanshan, Sun Yinhong. 1.5 kW polarization-maintained Yb-doped amplifier with 13 GHz linewidth by suppressing the self-pulsing and stimulated Brillouin scattering[J]. Applied Optics, 58, 6419(2019).

[44] Ott D, Divliansky I, Anderson B. Scaling the spectral beam combining channels in a multiplexed volume Bragg grating[J]. Optics Express, 21, 29620-29627(2013).

[45] [45] rusyak O, Ciapurin I, Smirnov V, et al. Spectral beam combining of fiber lasers with increased channel density[C]Proc of SPIE. 2007: 64531L.

[46] Schmidt O, Rekas M, Wirth C. High power narrow-band fiber-based ASE source[J]. Optics Express, 19, 4421-4427(2011).

[47] Naderi N A, Dajani I, and Flores A. High-efficiency, kilowatt 1034 nm all-fiber amplifier operating at 11 pm linewidth[J]. Optics Letters, 41, 1018-1021(2016).

[48] [48] Naderi N A, Fles A, erson B M, et al. Kilowatt highefficiency narrowlinewidth monolithic fiber amplifier operating at 1034 nm[C] Proc of SPIE. 2016: 972803.

[49] [49] Huang Y, Edgecumbe J, Ding J, et al. Perfmance of kW class fiber amplifiers spanning a broad range of wavelengths: 1028~1100 nm[C]Proc of SPIE. 2014:89612K.

[50] [50] Yagodkin R, Platonov N, Yusim A, et al.＞1.5 kW narrow linewidth cw diffractionlimited fiber amplifier with 40 nm bwidth[C]Proc of SPIE. 2016: 972807.

[51] Moloney J V, Newell A C. Nonlinear optics[J]. Physics D Nonlinear Phenomena, 44, 1-37(1990).

[52] Eidam T, Wirth C, Jauregui C. Experimental observations of the threshold-like onset of mode instabilities in high power fiber amplifiers[J]. Optics Express, 19, 13218-13224(2011).

[53] Smith A V, Smith J J. Mode competition in high power fiber amplifiers[J]. Optics Express, 19, 11318-29(2011).

[54] Hansen K R, Alkeskjold T T, Broeng J. Theoretical analysis of mode instability in high-power fiber amplifiers[J]. Optics Express, 21, 1944-1971(2013).

[55] Smith A V, Smith J J. Mode instability in high power fiber amplifiers[J]. Optics Express, 19, 10180-10192(2011).

[56] [56] Smith J J, Smith A V. Influence of signal bwidth on mode instability threshold of fiber amplifiers[C]Proceedings of SPIE. 2014: 93440L.

[57] Otto H J, Stutzki F, Jansen F. Temporal dynamics of mode instabilities in high-power fiber lasers and amplifiers[J]. Optics Express, 20, 15710(2012).

[58] Broderick N G R, Offerhaus H L, Richardson D J. Large mode area fibers for high power applications[J]. Optics Fiber Technology, 5, 185-196(1999).

[59] Shiraki K, Ohashi M, Tated M. Suppression of stimulated brillouin scattering in a fibre by changing the core radius[J]. Electronic Letter, 31, 668-669(1995).

[60] Jauregui C, Otto H J, Stutzki F. Passive mitigation strategies for mode instabilities in high-power fiber laser systems[J]. Optics Express, 21, 19375-19386(2013).