Fabrication of planar optical waveguides by K<sup>+</sup>-ion exchange in BK7 and Pyrex glass

Abstract

Planar graded index optical waveguides have been formed by K+ ion exchange in BK7 optical glass and Pyrex glass. Measurements of the mode indexes have been made and are well described by the WKB dispersion relation with a complementary error function refractive index profile for both glass types with refractive index changes ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Delta n</tex> ) of 0.0094 and 0.0073 for BK7 and Pyrex, respectively. A linear relation was found between the diffusion depth and the square root of the diffusion time for both materials, and effective diffusion coefficients were calculated. Diffusion times necessary to achieve a desired number of modes and diffusion depths have also been established.