Optical solitons in higher order nonlinear Schrodinger equation

We show the complete integrability and the existence of optical solitons of higher order nonlinear Schrodinger equation by inverse scattering method for a wide range of values of coefficients. This is achieved first by invoking a novel connection between the integrability of a nonlinear evolution equation and the dimensions of a family of matrix Lax pairs. It is shown that Lax pairs of different dimensions lead to the same evolution equation only with the coefficients of the terms in different integer ratios. Optical solitons, thus obtained by inverse scattering method, have been found by solving an n dimensional eigenvalue problem.