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. >

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

The refractive index profiles are investigated for Ag/sup +/-Na/sup +/ ion-exchanged waveguides in soda-lime glass. The waveguides with the highest index change, used to design homogeneous refracting waveguide lenses and prisms, are fabricated at 350 degrees C using concentrated melt with composition of 10 mol.% AgNO/sub 3/ and 90 mol.% NaNO/sub 3/. The profiles of two- and three-mode waveguides are reconstructed from the measured mode refractive indexes. The linear correlation between the index change and the silver concentration in glass is experimentally confirmed. The concentration profiles are numerically simulated on the base of diffusion-exchange theory. It is established that the values of the maximum in index profile near the glass surface tend to a saturation value after a long exchange time. >

Characterization of refractive index profiles in silver-sodium ion-exchanged glass waveguides for homogeneous refracting waveguide structures

A method for the determination of the refractive index of the surface layer of a matenal, about 5.0–10.0 nm thick, was developed and tested experimentally. The method was used to find the refractive index profile of thin-film waveguides prepared by diffusion in glass.

V N Sorokovikov

Papers

Diffraction method for measuring the refractive index on the surface of a material