MEASURING DISPERSION BETWEEN 2 MODES OF AN OPTICAL-FIBER USING TIME-DOMAIN AND SPECTRAL-DOMAIN LOW-COHERENCE INTERFEROMETRY

Group optical path difference (OPD) between two modes of an optical fi bre excited by a low-coherence source characterized by a multimode spe ctrum is evaluated measuring both the visibility dependence in the Mic helson interferometer configuration and the spectral modulation at the output of the optical fibre. Using the Fourier-transform method in pr ocessing the measured spectral modulations, a slight wavelength depend ence in the group OPD between two modes of the optical fibre is resolv ed. Comparing the group OPD corresponding to a central wavelength of t he measured spectral region with the group OPD obtained from the measu red visibility dependence, good agreement between results of the measu rements in the spectral domain and in the time domain is achieved.