Chirped optical solitons having polynomial law of nonlinear refractive index with self-steepening and nonlinear dispersion

We demonstrate the existence of chirped solitary waves in cubic-quintic-septimal materials under the influence of the Raman and self-steepening effects. We find new types of localized wave solutions that are characterized by an intensity-dependent frequency chirp, including dark and bright solitary waves. The nonlinearity in the frequency chirp associated with these localized pulses originates from the Raman and self-steepening processes. The formation of these nonlinearly chirped pulses is derived from parametric conditions. Effects of nonlinear parameters on the frequency chirp are discussed as well. The magnitude of the chirp can be efficiently governed by varying the self-steepening and Raman parameters. (C) 2021 Elsevier B.V. All rights reserved.