Integrated optical waveguiding structures made by silver ion-exchange in glass 2: Directional coupler and bends

It has been shown [ Appl. Opt.22, 0000 ( 1983)] that good quality stripe dielectric waveguides can be made by silver ion-exchange in glass if the diffusion mask is of alumina, made by anodization of an aluminum thin film. In this paper we present results of an experimental investigation of directional couplers, waveguide bends, and guide attenuation in waveguides of this type. Directional coupler transfer lengths are found to be in good agreement with theoretical prediction; bends behave as expected according to an approximate theory, and attenuation is found to be low (2dB/cm for a guide width of 2 μm). The optimum radius for a 2-μm wide monomode guide is found to be ~500 μm.