FIBER AND WAVE-GUIDE REFRACTIVE-INDEX MEASUREMENTS WITH AFM RESOLUTION

The use of preferential etching and atomic force microscopy to measure the refractive index profiles of optical fibres and silica waveguides is discussed. The validity of the technique itself is investigated. S everal types of fibres including an elliptical core fibre have been pr ofiled and the results compared to the preform refractive index profil es. Similarly, planar waveguides made by Plasma Enhanced Chemical Vapo ur Deposition (PECVD) have been measured and the results correlated wi th the fabrication process. The lateral resolution of this technique i s of order a few nanometers.