Chirped dark solitons in optical metamaterials

The ultrashort pulse propagation in metamaterials that is governed by the generalized nonlinear Schrödinger equation with pseudoquintic nonlinearity and self-steepening effect is investigated. By adopting a nonlinear chirp anstaz, we obtain an elliptic differential equation with a fifth-degree nonlinear term describing the evolution of the wave amplitude in the metamaterial. We present a variety of exact chirped dark soliton solutions for the model in the presence of the self-steepening term. The obtained results show that the corresponding chirp is proportional to the field intensity and depends on the self-steepening parameter. Parametric conditions on the metamaterial parameters for the existence of the dark structures as well as the nonlinear chirp associated with each of these optical pulses are also presented.