Exact N-Soliton Solutions for the Higher-Order Nonlinear Schrödinger Equation Under Another Condition

By using a simple transformation approach, we solve the higher-order nonlinear Schrödinger equation under another condition. The obtained exact soliton solutions have the following prominent features: The bright soliton can propagate in both the normal and anormal regions; the soliton travelling speed is proportional to its amplitude square; the phase of the soliton is independent of its amplitude or width; and the component solitons of the bound soliton have the same phase.