[1] Richardson D J, Nilsson J, Clarkson W A. High power fiber lasers: Current status and future perspectives [Invited][J]. Journal of the Optical Society of America B, 27, B63(2010).

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

[3] Stutzki Fabian, Jansen Florian, Otto Hans-Jürgen, et al. Designing advanced very-large-mode-area fibers for power scaling of fiber-laser systems[J]. Optica, 1, 233(2014).

[4] Lingfa Zeng, Xi Xiaoming, Ye Yun. Near-single-mode 3 kW monolithic fiber oscillator based on a longitudinally spindle-shaped Yb-doped fiber[J]. Optics Express, 45, 5792-5795(2020).

[5] Xiaoming Xi, Peng Wang, Baolai Yang, et al. The output power of the all-fiber laser oscillator exceeds 7 kW[J]. Chinese Journal of Lasers, 48, 0116001(2021).

[6] [6] Wang Y, Kitahara R, Kiyoyama W, et al. 8kW singlestage allfiber Ybdoped fiber laser with a BPP of 0.50 mmmrad[C]Proc of SPIE, 2020, 11260: 1126022.

[7] Ma Pengfei, Xiao Hu, Leng Jinyong, et al. Narrow linewidth fiber laser breaks through 4 kW near single mode output[J]. Infrared and Laser Engineering, 50, 20200421(2021).

[8] Ma Pengfei, Ma Yanxin, Su Rongtao, et al. Coherent synthesis of 8 kW fiber laser with high quality and high efficiency (brief news)[J]. Infrared and Laser Engineering, 49, 20200577(2020).

[9] [9] Christian Wirth, Thomas Schreiber, Miroslaw Rekas, et al. Highpower linearpolarized narrow linewidth photonic crystal fiber amplifier[C]Proc of SPIE, 2010, 7580: 75801H.

[10] Tao Rumao, Su Rongtao, Ma Pengfei, et al. Suppressing mode instabilities by optimizing the fiber coiling methods[J]. Laser Physics Letters, 14, 25101(2017).

[11] Ye Yun, Xi Xiaoming, Shi Chen, et al. Comparative study on transverse mode instability of fiber amplifiers based on long tapered fiber and conventional uniform fiber[J]. Laser Physics Letters, 16, 85109(2019).

[12] Lin Aoxiang, Zhan Huan, Peng Kun, et al. 10 kW-level pump-gain integrated functional laser fiber[J]. High Power Laser and Particle Beams, 30, 180110(2018).

[13] Wang Jianjun, Liu Yu, Li Min, et al. Ten-year review and prospect on mode instability research of fiber lasers[J]. High Power Laser and Particle Beams, 32, 121003(2020).

[14] Xiaolin Wang, Pin Lv, Hanwei Zhang, et al. Fiber laser simulation software see fiber laser and fiber laser tool collection SFTool[J]. Chinese Journal of Lasers, 44, 0506002(2017).

[15] Smith A V, Smith J J. Steady-periodic method for modeling mode instability in fiber amplifiers[J]. Optics Express, 21, 2606-2623(2013).

[16] Wang Xiaolin, Zhang Hanwei, Yang Baolai, et al. High-power ytterbium-doped fiber laser oscillator current situation and future developments[J]. Chinese Journal of Lasers, 48, 401001(2021).

[17] Yang Baolai, Zhang Hanwei, Wang Xiaolin, et al. Mitigating transverse mode instability in a single-end pumped all-fiber laser oscillator with a scaling power of up to 2 kW[J]. Journal of Optics, 18, 105803(2016).

[18] Li Xuewen, Yu Chunlei, Shen Hui, et al. Thermo-optic effect and mode instability threshold characteristics of high-power fiber laser[J]. Chinese Journal of Lasers, 46, 1001001(2019).

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

[20] Haarlammert Nicoletta, de Vries Oliver, Liem Andreas, et al. Build up and decay of mode instability in a high power fiber amplifier[J]. Optics Express, 20, 13274-13283(2012).

[21] Tao R, Ma P, Wang X, et al. Mitigating of modal instabilities in linearly-polarized fiber amplifiers by shifting pump wavelength[J]. Journal of Optics, 17, 45504(2015).

[22] Tao R, Wang X, Zhou P. Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications[J]. IEEE Journal of Selected Topics in Quantum Electronics, 24, 1-19(2018).