[1] [1] Snitzer E, Po H, Hakimi F,et al. Double-clad, offset core Nd fiber laser, Proc. Optical Fiber Sensors, 1988, Washington, D.C. Paper PD5

[4] [4] Bedo S, Luthy W, Weber H P.The effective absorption coefficient in double-clad fibers. Opt Commun,1993, 99: 331～335

[5] [5] Muendel M H.Optical inner cladding shapes for double-clad fiber lasers, Dig. Conference on Lasers and Electro-Optics(CLEO'96), 1996.Paper CTuU2

[6] [6] Chernikov S V, Zhu Y, Taylor J R. Supercontinum self-Q-switched ytterbium fiber laser.Opt Lett, 1997,22(5): 298～300

[7] [7] Liu A, Ueda K. The absorption characteristics of circular, offset, and rectangular double-clad fibers. Opt Commun, 1996,132: 511～518

[8] [8] Doya V, Legrand O, Mortessagne F. Optimized absorption in a chaotic double-clad fiber amplifier. Opt Lett, 2001,26(12): 872～874

[9] [9] Unger H G. Planar Optical Waveguides and fibers.Oxford: Clarendon Press, 1977,Chapter 2

[10] [10] Marcuse D. Theory of Dielectric Optical Waveguides.New York: Academic Press, 1974,Chapter 5