Parabolic pulse generation in short fiber amplifiers

The evolution of a laser pulse in a normal dispersion fiber amplifier is studied numerically. The cases of amplification with ideal spectrally flat gain and amplification with spectrally parabolic gain are considered. It is shown that the transformation of the input pulse envelope into parabolic form is possible, not only for spectrally flat but also for spectrally limited gain. In the last case, the important parameter is the optimal length of the amplifier. The results show that for a sufficiently broadband gain, it is always possible to find the optimal amplifier length, which provides the output pulse with envelope close to the parabola. (paper)