Low-coherence spectral interferometry with a Michelson interferometer applied to dispersion measurement of a two-mode optical fiber

摘要

Abstract: Intermodal dispersion in a two-mode optical fiber canbe measured in the spectral domain when the spectralinterference between modes at the output of the opticalfiber shows up as a periodic modulation of the sourcespectrum that can be processed. However, this techniquecannot be used to measure intermodal dispersion in thetwo- mode optical fiber when the period of modulationis too small to be resolved by a spectrometer.Consequently, we proposed a new measuring techniqueutilizing a tandem configuration of a dispersiveMichelson interferometer and the two-mode optical fiberin which the spectral interference can be resolved evenif a low-resolution spectrometer is used. In the tandemconfiguration of the Michelson interferometer and thetwo-mode optical fiber, the optical path difference(OPD) in the Michelson interferometer is adjusted closeto the group OPD between modes of the optical fiber sothat the low-frequency spectral modulation that can beprocessed is produced. Using the Fourier transformmethod in processing the measured spectral modulationsand subtracting the effect of the dispersive Michelsoninterferometer, the feasibility of this technique hassuccessfully been demonstrated in obtaining theintermodal dispersion in the two-model optical fiber.!17