Quasi-soliton propagation along a dispersion-profiled fibre using second-order moment theory

We show, through second order moment theory, the existence of a new regime of self-similar chirped-solitary wave in an appropriately dispersion-profiled fibre. This study completes the concept of quasi-solitons introduced by Kumar and Hasegawa. Theory reveals the existence of an invariant relation respected by quasi-solitons. This invariant relation can be fully recovered by the usual variational approach of the non-linear Schroedinger equation (NLS) and it can be used to study non-linear pulse propagation in constant dispersion optical fibers and ultimately for dispersion management. The work has been carried out for the lossless as well as for the lossy case.