THEORY OF SOLITON PULSE FORMING IN AN ACTIVELY MODELOCKED FIBER LASER

Generation of subpicosecond solitons in active modelocked fiber lasers is investigated, both analytically and numerically. The laser model t akes into account the pulse dispersive spreading, self-phase modulatio n, finite amplification bandwidth, pump depletion and Raman self-frequ ency shift. Our analytical theory, which is based on the inverse scatt ering method perturbation approach, allows us to calculate the steady- state parameters of the soliton pulse. The analytic predictions are co nfirmed by numerical simulation. It is shown that the minimal pulse du ration may be achieved provided that the Raman self-frequency shift is suppressed by the phase modulator.