Solitons in fibre lasers and mode-locked systems

Soliton propagation in a laser fibre is investigated using multiple-scale perturbation analysis. The perturbative terms are linear loss and saturable nonlinear gain. Furthermore, we show the possibility of stable soliton-like propagation in an amplitude pulse mode-locked system consisting of a semiconductor laser coupled to a nonlinear fibre through a centre mirror. The soliton-like pulse is slightly asymmetric due to asymmetric gain amplification in the semiconductor laser.