Nonlinear polarization evolution: a numerical study of the coupling between main linear normal modes

A numerical modelling of nonlinear changes of polarization by Kerr effect is presented for an optical field propagating along a birefringent silica optical fiber. The kernel of this model comes from expressing the coupled field as a sum of two linear polarization modes in the direction of the fiber principal axes. The developed model is suitable for the design of optoelectronic devices and permits easily taking into account chromatic dispersion, gain or loss, etc.