Method of refractive index profile reconstruction from effective index of planar optical monomode waveguides: Application to potassium ion-exchanged waveguides

A simple nondestructive method for determination of refractive index profile of single-mode waveguides using the measured effective refractive indexes is proposed. The method is based on the extraction of the additional data about the waveguide profile from the investigation of its evolution with the duration of fabrication process. The profile reconstructions are carried out using an appropriate algorithm in the frames of the WKB approximation. The method is applied for few- and single-mode waveguides, obtained by K/sup +/-Na/sup +/ field assisted ion exchange. The results are corroborated with the reconstruction from the effective refractive indexes measured at a shorter wavelength, as well as with profile study by means of step-by-step etching.>