New types of exact quasi-soliton solutions in metamaterials

Abstract

We consider a generalized nonlinear Schrödinger equation describing the propagation of ultrashort pulses in metamaterials (MMs) and present three new types of exact bright, dark, bright-grey quasi-solitons with a free constant associated with their amplitudes, pulse widths and formation conditions. Based on the Drude model, we analyze the existence regions and characteristics of these quasi-solitons in MMs. The results show that these bright and dark (grey) quasi-solitons can exist in wider regions of MMs and their intensities and pulse widths can be adjusted by choosing a suitable free constant. Furthermore, we take the third type of quasi-soliton solution as an example to numerically discuss the stabilities under slight perturbations of the frequency and the initial pulse width. The obtained results are helpful in exploring more solitary waves in MMs and providing a new reference for experimental verification.