USE OF MULTIPLE-WAVELENGTH AND OR TE/TM EFFECTIVE-REFRACTIVE-INDEX MEASUREMENTS TO RECONSTRUCT REFRACTIVE-INDEX PROFILES/

A method is presented whereby the refractive-index profile of a planar , surface-dielectric optical waveguide may be reconstructed from sets of effective refractive indices, measured at different wavelengths and /or with sets of effective refractive indices measured with TE and TM polarisation. The index change and the substrate index may be waveleng th dispersive and birefringent. The method is compared, both theoretic ally and experimentally, with conventional single-wavelength method fo r a number of index profiles. This technique provides more information about the profile than can be obtained from one measured set and is u sed to analyse the index profiles of potassium ion exchange guides for med in soda-lime glass. The limitations of the technique are also disc ussed.