[5] [5] A. Asseh, H. Storoy, J. T. Kringlebotn et al.. 10 cm Yb3+ DFB fibre laser with permanent phase shifted grating [J]. Electron. Lett., 1995, 31(12):969～970

[6] [6] R. Paschotta, J. Nilsson, L. Reekie et al.. Single-frequency ytterbium-doped fiber laser stabilized by spatial hole burning [J]. Opt. Lett., 1997, 22(1):40～42

[7] [7] Masashi Usami, Shigeyuki Akiba, Katsuyuki Utaka. Asymmetric λ/4-shifted InGaAsP/InP DFB lasers [J]. IEEE J. Quantum Electron., 1987, QE-23(6):815～821

[8] [8] H. A. Haus, C. Shank. Antisymmtric taper of distributed feedback lasers [J]. IEEE J. Quantum Electron., 1976, QE-12(9):532～539

[9] [9] H. Kogelnik, C. V. Shank. Coupled-wave theory of distributed feedback lasers [J]. J. Appl. Phys., 1972, 43(5):2327～2335