DETERMINATION OF THE MATERIAL DISPERSION AND THE INDEX PROFILE PARAMETERS OF A GRIN OPTICAL WAVE-GUIDE APPLYING WHITE-LIGHT INTERFERENCE-FRINGES

Multiple-beam white light fringes across a graded-index optical wavegu ide enclosed in a liquid wedge interferometer and followed by a gratin g spectrograph are obtained. An accurate approach for interferogram an alysis and data reduction is applied. The material dispersions of the immersion liquid, the cladding and the core of the fibre across the vi sible spectrum are deducted. Also the index profile parameters of the fibre are evaluated. A modified single-term Sellmeier dispersion formu la is adopted and fitted to the experimental data.