Modeling and design for an electrooptic directional coupler modulator

A numerical model is presented for an electrooptic directional coupler modulator. The model depends on the analysis of simple coplanar uniform electrodes. The analysis is based on the transverse resonance technique. An equivalent circuit is deduced to represent the structure of the modulator. General trial quantities are introduced as virtual adjustable sources in the equivalent circuit. It was observed that it is possible for such a device to be optimized by the variation of a number of fabrication parameters. The applied field and the change in optical waveguides optical field due to the antisymmetric refractive index change are calculated for the structure. Finally, the product of switching voltage and coupling length and optical loss due to the metal electrodes are also investigated.