White-light spectral interferometry used to measure dispersion characteristics of optical fibers

A new spectral-domain white-light interferometric technique employing a low-resolution spectrometer is used to measure dispersion characteristics of two-mode optical fibers. The technique utilizes the fact that the spectral interference fringes are resolved at the output of a tandem configuration of the compensated (non-dispersive) Michelson interferometer and a two-mode optical fiber only in the vicinities of so-called equalization wavelengths at which the optical path difference (OPD) in the interferometer is the same as the intermodal group OPDs. The white-light spectral interferometric technique is used to measure the spectral dependences of both the differences between propagation constants of modes and the intermodal group OPD for elliptical-core (highly birefringent) optical fibers. The measured dispersion characteristics of the optical fibers are compared with those corresponding to the results of an adequate theoretical analysis using the known parameters of the optical fibers.