Self-referencing dispersion characterization of multimode structures using direct instantaneous frequency measurement

A technique for the simultaneous self-referencing characterization of the chromatic dispersion of the modes of a multimode structure is presented. The frequency-dependent group delay of each mode is extracted independently using Fourier processing of the temporal and spectral intensities measured after propagation of a short pulse in the structure under test and an interferometer. As an experimental demonstration, we have characterized the chromatic dispersion of the two modes of a fiber typically used for constructing high-order mode dispersion-compensating modules.