[7] [7] Hotdel W, Schütz J, Weber H P. Limits to the amplification efficiency of ultrashort fundenmental solitons using Er-doped fibers [J]. Opt. Commun., 1992, 88: 173-179.

[8] [8] Agrawal G P. Amplification of ultrashort solitons in erbium-doped fiber amplifiers [J]. IEEE Photon. Technol. Lett., 1990, 2(12): 875-877.

[9] [9] Wai P K A, Cao W H. Simultaneous amplification and compression of ultra-short solitons in an erbium-doped nonlinear amplifying fiber loop mirror [J]. IEEE J. Quantum Electron., 2003, 39(4): 555-561.

[10] [10] Mark D P, Liu H F. Higher order soliton pulse compression in dispersion-decreasing optical fibers [J]. IEEE J. of Quantum Electron., 1997, 33(8): 1430-1439.

[11] [11] Agrawal G P. Nonlinear Fiber Optics [M]. 3rd ed. California: Academic Press Inc., 1995. 201-218.

[12] [12] Finot C, Millot G, Billet C, et al. Experimental generation of parabolic of pulses via Raman amplification in optical fiber [J]. Opt. Expr., 2003, 11(13): 1547-1552.

[13] [13] Hirooka T, Nakazawa M. Parabolic pulse generation by use of a dispersion-decreasing fiber with normal group-velocity dispersion [J]. Opt. Lett., 2004, 29(5): 498-500.

[15] [15] Agrawal G P. Nonlinear Fiber Optics [M]. 3rd ed. California: Academic Press Inc., 1995. 408-509.