Measurements of intermodal dispersion in few-mode optical fibres using a spectral-domain white-light interferometric method

A spectral-domain white-light interferometric technique employing a low-resolution spectrometer is used in measurement of the intermodal dispersion in optical fibres. The technique utilizes a tandem configuration of a compensated Michelson interferometer and a few-mode optical fibre and the resolving of so-called equalization wavelengths at which the optical path difference (OPD) in the interferometer is the same as the intermodal group OPDs. The intermodal dispersion in three different optical fibres was measured and the results for two of them were compared with the results of an adequate theoretical analysis using a model of a weakly guiding, step-index optical fibre.