Alternative coupled integrable optical soliton system with higher-order effects.

The system of coupled Hirota equations, which explains the simultaneous propagation of two fields in a nonlinear optical fiber with the inclusion of higher-order linear and self-steepening effects, is considered. By making use of a Painlevé singularity structure analysis, the system is found to be an exactly integrable soliton system for three choices of physical parameters. Two of the soliton conditions are already well studied. For the third system, the soliton solutions are obtained using bilinear forms.