[3] [3] Knight J C,Birks T A,et al. All-silica single-mode optical fiber with photonic crystal cladding [J].Opt. Lett.,1996,21(19):1547-1549.

[4] [4] Birks T A,et al. Endlessly single-mode photonic crystal fiber [J].Opt. Lett.,1997,22(13):961-963.

[5] [5] Luan F,George A K,et al. All-solid photonic bandgap fiber [J].Opt. Lett.,2004,29(20):2369-237.

[6] [6] Nilsson J,Yun S Y,Hwang S T,et al. Long-wavelength erbium-doped fiber amplifier gain enhanced by ASE end-reflectors [J].Photonics Technology Lett.,1998,10(11):1551-1553.

[7] [7] Masaharu H,et al. Erbium-doped optical fiber amplifiers pumped in the 66～820 nm bands [J].Journal of Lightwave Technology,1994,12(5):810-820.

[8] [8] Francesco P. Erbium-doped hole-assisted optical fiber amplifier: design and optimization [J].Journal,of Lightwave Technology,2005,23(1):330-340.

[9] [9] Makoto Y,et al. Gain characteristics of an Er3+-doped multicomponent glass single-mode optical fiber [J].Photonics Technology Lett.,1990,2(9):656-658.

[10] [10] Di Pasquale F,et al. Analysis of erbium-doped waveguide amplifiers by a full-vectorial finite-element method [J].Journal of Lightwave Technology,1993,11(10):1565-1574.

[11] [11] Ho K M,et al. Existence of a photonic gap in periodic dielectric structures [J].Phys. Rev. Lett.,1990,65(25):3152-3155.

[12] [12] Mortensen N A,Folkenberg J R,et al. Modal cutoff and the V parameter in photonic crystal fibers [J].Opt.Lett.,2003,28(20):1879-1881.