Scanning technique for investigating optical fibre dispersion

Differential mode delay measurements have been performed, both for step-index and for graded-index fibres, using a sinusoidally modulated optical source. From a differential mode delay measurement, it is possible to get all the information on the fibre baseband response with or without the effect of skew rays, and in particular of leaky rays. A theoretical model of mode coupling is developed and is used for computing the baseband response for fibres where mode coupling is not negligible.