A generalized input polarization analysis of the relative state of polarization between two signals in highbirefringence
fibers is presented. The degree of co-polarization is calculated as a function of the polarization
orientation and ellipticity of the two input signals, for two different input polarization schemes. It is shown that
for small fiber lengths or narrow wavelength separation, launching the two signals with orthogonal polarizations
can present a higher degree of co-polarization along the propagation. For higher ellipticity values the dependence
of the degree of co-polarization on the angle between the major axis of the ellipsis and the principal axes
vanishes.