Fiber-compatible K+-Na+ ion-exchanged channel waveguides: fabrication and characterization

A systematic study of waveguides fabricated by K( )-Na ( ) exchange in soda-lime silicate and BK7 glasses is presented. The measured K( ) concentration profile, the refractive index profile, and the diffusion profile obtained by solving the one-dimensional diffusion equation are correlated to explain the differences in the index profiles in the two glasses. The mobility of the potassium ions was measured by fabricating waveguides using electromigration. Surface waveguides formed by diffusion from a molten KNO(3) salt bath were buried by applying an electric field. Single-mode channel waveguides for operation at a wavelength of 1.3 mum that exhibit excellent mode matching with conventional optical fibers, achieving a fiber-waveguide insertion loss of less than 1 dB for a 20-mm-long waveguide, have been obtained