Considerations on group delay fitting equations for dispersion-shifted fibres

Chromatic dispersion measurement accuracy was examined experimentally for four kinds of group delay fitting equation which have been proposed to date. It was found that the five-term Sellmeier equation is appropriate for dispersion-shifted fibres with various refractive index profiles. Also, it was demonstrated that the maximum difference in zero-dispersion wavelength among the four equations is less than 0.67nm by selecting six measuring wavelengths between 1.49¿m and 1.59¿m using the LD phase-shift method.