DIFFUSION AND PROPAGATION CHARACTERISTICS OF BURIED SINGLE-MODE WAVE-GUIDES IN GLASS

Diffusion and propagation characteristics of single-mode shallow buried planar waveguides fabricated by purely thermal back diffusion of K+ ions in soda-lime glass are presented. The refractive index profile is determined using scanning electron microscopy and theoretically modeled by a Rayleigh function after solving the diffusion equation numerically. The dispersion curves are computed by solving the Helmholtz equation with a Runge-Kutta procedure and agree well with measured mode indexes. A decrease in the birefringence of the waveguides is observed by increasing the back diffusion time. Measured propagation losses remain less than 1.0 dB/cm for short back diffusion times at a wavelength of 0.633-mu-m.