Determination of the material dispersion and the index profile parameters of a GRIN optical waveguide applying white light interference fringes

Abstract

Multiple-beam white light fringes across a graded-index optical waveguide enclosed in a liquid wedge interferometer and followed by a grating spectrograph are obtained. An accurate approach for interferogram analysis and data reduction is applied. The material dispersions of the immersion liquid, the cladding and the core of the fibre across the visible spectrum are deducted. Also the index profile parameters of the fibre are evaluated. A modified single-term Sellmeier dispersion formula is adopted and fitted to the experimental data.