On the prolongation structure and integrability of HNLS equation

Higher order nonlinear Schrödinger equation occurring in the field of nonlinear optics is analysed from the view point of prolongation theory and Painléve analysis. The gauge equivalence of the equation to the complex modified K dV equation is never used. But from our direct analysis we can sort out the various relations as existing between the parameters of the equation for which it is integrable and one can have a Lax pair.