Refractive index profile reconstruction from near-field measurements: analysis and assessment

In this paper we present a critical analysis on the refractive index profile reconstruction from near field measurements. We show that the near field information is not sufficient to uniquely determine the proper index parameters if the refractive index shape it is not already known a priori and then we propose a technique to refine the results found from the inversion. Experimental verifications in the case of waveguides made by ion exchange in a glass substrate confirm the results obtained with simulations