Intermodal interference in photonic crystal fibers

The equipment for intermodal interference investigation is described. The results of an investigation of intermodal interference within a photonic crystal fibre (from Centaurus Technologies, Sydney) in terms of length and frequency region are presented. From the measured values the difference of the phase constant of the fundamental and the first higher order (antisymmetric) modes, as well as the decay constant of the mode in the wavelength region exceeding the two modes region, are determined.