Propagation of dark solitons in a system of coupled higher-order nonlinear Schrödinger equations

In this paper, we consider the higher-order linear and nonlinear effects in optics and analyse a coupled system of higher-order nonlinear Schrödinger equations to identify the conditions for dark-soliton propagation through Painlevé analysis, to supplement the known bright-soliton conditions. We also construct the explicit Lax pair and the Hirota bilinear form is used to generate one and two dark solitons.