Localized pulses in optical fibers governed by perturbed Fokas–Lenells equation

We study the existence and properties of propagating solitary waves in an optical fiber medium described by the perturbed Fokas-Lenells equation. Additional effects to the usual Fokas-Lenells equation include third- and fourth-order dispersions, inter-modal dispersion, nonlinear dispersion and self-steepening effect. The model applies to the description of light pulse propagation applicable to a femtosecond or subpicosecond regime. We introduce an efficient ansatz for the field amplitude that enables us to obtain solitary waves with the governing model. More pertinently, we find that solitary wave solutions of bright and dipole shape do exist in the presence of all orders of dispersion and various nonlinear effects. We also find that the energy associated to the obtained structures depends on all material parameters. The requirements concerning the optical fiber parameters for the existence and uniqueness of such solitary waves are presented.