Propagation properties of self-similar pulses in normal-dispersion fiber amplifiers

Self-similarpulse propagation properties in Yb+3-doped fiber amplifiers with the effects of higher-order dispersion and gain dispersion have been studied in this paper. The effects of initial pulse energy, third-order dispersion and the doped ions dipole relaxation time on the pulse propagation quality are relatively expounded with the analytical and simulative methods. It is shown that with nonlinear area of parabolic pulses being enlarged, the center of chirp moves forward or backward, due to the difference of third-order dispersion coefficient. And the figure of pulses is distorted with the pulse peak delaying to one side and the center location excursing. Gain dispersion can be a filter, which can properly compress pulse-width. Results proved the possibility of the self-similar pulse existing in gain medium with a certain relaxation time.