title: W-shaped solitons generated from a weak modulation in the Sasa-Satsuma equation.
abstract: We study rational solutions of continuous wave backgrounds with the critical frequencies of the Sasa-Satsuma equation, which can be used to describe the evolution of the optical field in a nonlinear fiber with some high-order effects. We find a striking dynamical process that two W-shaped solitons are generated from a weak modulation signal on the continuous wave backgrounds. This provides a possible way to obtain stable high-intensity pulses from a low-intensity continuous wave background. The process involves both modulational instability and modulational stability regimes, in contrast to the rogue waves and W-shaped solitons reported before which involve modulational instability and stability, respectively. Furthermore, we present a phase diagram on a modulational instability spectrum plane for the fundamental nonlinear localized waves obtained already in the Sasa-Satsuma equation. The interactions between different types of nonlinear localized waves are discussed based on the phase diagram.
authors.affiliation: Department of Physics, Northwest University, 710069, Xi'an, China.
authors.forename: Li-Chen
authors.initials: LC
authors.lastname: Zhao
authors.affiliation: School of Science, Xi'an Jiaotong University, 710049, Xi'an, China.
authors.forename: Sheng-Chang
authors.initials: SC
authors.lastname: Li
authors.affiliation: School of Mathematics, South China University of Technology, 510640, Guangzhou, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Ling