[1] [1] Wang Xiaolin, Leng Jinyong, Du Wenbo, et al. 275 W MOPA all fiber narrow linewidth ytterbium doped fiber laser［J］. Chinese J Lasers, 2011, 38(3): 0308001.

[3] [3] Wang Xiaolin, Tao Rumao, Zhang Hanwei, et al. 1 kilowatt single-end pumped all-fiber laser oscillator with good beam quality and high stability ［J］.Chinese J Lasers, 2014, 41(11): 1105001.

[4] [4] Wang Xiaolin, Zhang Hanwei, Tao Rumao, et al. Laser diode pumped 4.1 kW all-fiber laser with master oscillator power amplification configuration［J］. Chinese J Lasers, 2016, 43(5): 0502002.

[5] [5] Zervas M N, Codemard C A. High power fiber lasers: a review ［J］. IEEE Journal of Selected Topics in Quantum Electronics, 2014, 20(5): 0904123.

[6] [6] Fan Y Y, He B, Zhou J, et al. Thermal effects in kilowatt all-fiber MOPA［J］. Optics Express, 2011, 19(16): 15162-15172.

[7] [7] Wang Xiaolin, Zhou Pu, Xiao Hu, et al. Narrow linewidth all-fiber laser with 666 W power output［J］. High Power Laser and Particle Beams, 2012, 24(6): 1261-1262.

[8] [8] Ward B, Robin C, Dajani I. Origin of thermal modal instabilities in large mode area fiber amplifiers［J］. Optics Express, 2012, 20(10): 11407-11422.

[9] [9] Brar K, Savage-Leuchs M, Henrie J, et al. Threshold power and fiber degradation induced modal instabilities in high power fiber amplifiers based on large mode area fibers［C］. SPIE, 2014, 8961: 89611R.

[10] [10] Wang X L, Zhou P, Leng J Y, et al. A 330-W single-frequency retrievable multi-tone monolithic fiber amplifier［J］. Chinese Physics B, 2013, 22(4): 044205.

[11] [11] Wang X, Leng J, Zhou P, et al. 1.8-kW simultaneous spectral and coherent combining of three-tone nine-channel all-fiber amplifier array［J］. Applied Physics B: Lasers and Optics, 2012, 107(3): 785-790.

[12] [12] Wang X L, Zhou P, Xiao H, et al. 310 W single-frequency all-fiber laser in master oscillator power amplification configuration［J］. Laser Physics Letters, 2012, 9(8): 591-595.

[13] [13] Froggatt M E, Gifford D K, Kreger S, et al. Characterization of polarization-maintaining fiber using high-sensitivity optical-frequency-domain reflectometry［J］. Journal of Lightwave Technology, 2006, 24(11): 4149-4154.

[14] [14] Zhou Zichao, Wang Xiaolin, Su Rongtao, et al. Application of distributed fiber sensing in fiber lasers［J］. Laser & Optoelectronics Progress, 2016, 53(8): 080006.

[15] [15] Beier F, Heinzig M, Haarlammert N, et al. In situ temperature measurement in high power fiber amplifiers［C］. ECLEO-EQEC, 2015: CJ-10-6.

[16] [16] Beier F, Heinzig M, Walbaum T, et al. Determination of thermal load from core temperature measurements in single mode ytterbium-doped fiber amplifiers［C］. ECLEO-EQEC, 2015: ATh2A.23

[17] [17] Eickhoff W, Ulrich R. Optical frequency domain reflectometry in single-mode fiber［J］. Applied Physics Letter, 1981, 39(9): 693-695.