INTEGRABILITY AND SINGULARITY STRUCTURE OF COUPLED NONLINEAR SCHRODINGER-EQUATIONS

Multimode propagation of electromagnetic waves in optical fibre is oft en described by coupled nonlinear Schrodinger (NLS) equations. To unde rstand the integrability properties of such coupled NLS systems, we ex tend the Painleve singularity structure analysis of two coupled system s to three coupled systems and identify four integrable sets of parame ters. We bilinearize these cases to obtain soliton solutions. The resu lts are extended to N-coupled systems, completing the earlier analysis of Sahadevan, Tamizhmani and Lakshmanan.