Collisions of three higher order dark double- and single-hump solitons in optical fiber

Abstract

In this paper, the coupled higher-order nonlinear Schrödinger (CHNLS) equations governing the ultrashort soliton pulse transmission in a two-mode or birefringent fiber are studied. The dark double-hump (DDH) three-solion solutions with higher order effects are derived by the Hirota method. Based on the solutions, the elastic collisions of DDH solitons, the anti-dark solitons and anti-dark soliton molecule are revealed in two modes. The differences of collision dynamics are discussed when three solitons colliding separately and simultaneously. We find the soliton molecule bound by anti-dark, kink and anti-kink solitons. Moreover, the effects of the group velocity dispersion (GVD), self-steepening (SS) and third-order dispersion (TOD) on the collisions are analysed. Those researches are valuable to the development of ultrashort pulse fiber laser and optical fiber communication. We also hope that those results contribute to the study of soliton molecules.