Modulation instability, rogue waves and spectral analysis for the sixth-order nonlinear Schrodinger equation

Abstract

Modulation instability, rogue wave and spectral analysis are investigated for the nonlinear Schrödinger equation with the higher-order terms. The modulation instability distribution characteristics from the sixth-order to the eighth-order nonlinear Schrödinger equations are studied. Higher-order dispersion terms are closely related to the distribution of modulation stability regime, and n-order dispersion term corresponds to n − 2 modulation stability curves in the modulation instability band. Based on the generalized Darboux transformation method, the higher-order rational solutions are constructed. Then the compact algebraic expression of the Nth-order rogue wave is given. Dynamic phenomena of firstto third-order rogue waves are illustrated, which exhibit meaningful structures. Two arbitrary parameters play important roles in the rogue wave solution. One can control deflection of crest of rogue wave and its width, while the other can cause the change of width and amplitude of rogue wave. When it comes to the third-order rogue wave, three typical nonlinear wave constructions, namely fundamental, circular and triangular are displayed and discussed. Through the spectral analysis on first-order rogue wave, when these parameters satisfy certain conditions, it occurs a transition between W-shaped soliton and rogue wave.

Unconditional uniqueness of higher order nonlinear Schrödinger equations

“…The biharmonic NLS provides a canonical model for nonlinear partial differential equations of super-quadratic order. The study of biharmonic NLS goes back to [21] and [22] where the partial differential equation was introduced to take into account the role of small fourth-order dispersion terms in the propagation of intense laser beams in a bulk medium with Kerr nonlinearity (for applications of higher order NLS, such as sixth and eighth order NLS, see [9], [20], [32] and [34]).…”