Time-domain intermodal interference including higherorder dispersion effects

Abstract

The intermodal interference is analysed theoretically at the output of both a few-mode optical fibre alone and a tandem configuration of a Michelson interferometer with an optical fibre when higher-order intermodal dispersion effects are taken into account. It is revealed theoretically that in a special case of a two-mode optical fibre with a quadratic spectral dependence of the difference of propagation constants, which includes the equalization frequency with zero intermodal group delay, and fibre excitation by a broad-band light source, the time-domain visibility functions differ substantially from those corresponding to fibre excitation by a low-coherence light source. Moreover, measuring a two-mode optical fibre using time-domain and spectral-domain white-light interferometric techniques, some theoretical results are confirmed experimentally.