General N-soliton solution to a vector nonlinear Schrödinger equation

Abstract

We consider a general N-soliton solution to a vector nonlinear Schrödinger (NLS) equation of all possible combinations of nonlinearities including all-focusing, all-defocusing and mixed types. Based on the KP hierarchy reduction method, we firstly construct general two-bright-one-dark and one-bright-two-dark soliton solutions in a three-coupled NLS equation, then we extend our analysis to a vector NLS equation to obtain a general N-soliton solution in Gram determinant form. This formula unifies the bright, dark and bright-dark soliton solutions, which have been widely studied in the literature. The conditions for the existence of all types of soliton solutions with all possible combinations of nonlinearities are elucidated.