Modulation instability in an extended nonlinear Schroedinger equation.

We have examined modulation instability in an extended nonlinear Schroedinger equation. The frequency dependence of the eigenmodes propagating in the fiber has been included and expressed in terms of a measurable parameter. This parameter depends on the index of refraction profile and core size of the fiber which can be controlled in fiber fabrication. Thus this parameter may allow modification of the modulation instability in an optical fiber system. In addition, we have found that high- order-odd dispersion does not influence the frequency at which modulation instability achieves its maximum growth.