[1] E. Snitzer, H. Po, F. Hakima et al.. Double-clad, offset core Nd fiber laser [C]. in Optical Fiber Sensors, OSA Technical Digest Series, 1998. 2: PDS

[2] D. Gapontsev. 6 kW CW single mode ytterbium fiber laser in all-fiber format[C]. Conf. on Solid State and Diode Laser Technology Review (SSDLTR) in Albuquerque, New Mexico, 2008

[3] D. C. Jones, A. M. Scott. A model of a fiber amplifier incorporating amplified spontaneous emission [C]. SPIE, 2004, 5335: 73～80

[4] A. Bouchier, G. Lucas-Leclin et al.. Theoretical and experimental investigations of a single-mode 976-nm Yb-doped fiber amplificer[C]. SPIE, 2004, 5460: 23～30

[5] Yin Shupeng, Yan Ping, Li Chen et al.. Extraction efficiency in contiuous-wave ytterbium-doped fiber amplifier[J]. Chinese J. Lasers, 2008, 35(6): 835～839

[6] Chang Liping, Fan Wei, Wang Li et al.. Amplification performance of large- and small-mode-area ytterbium-doped double-clab fiber amplifier[J]. Chinese J. Lasers, 2007, 34(11): 1492～1497

[7] R. Paschotta, J. Nilsson, A. C. Tropper et al.. Ytterbium-doped fiber amplifers[J]. IEEE J. Quantum Electron., 1997, 33(7): 1049～1056