Design considerations for an electrooptic directional coupler modulator

A rigorous numerical model is presented for an electrooptic directional coupler (DC) modulator. 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, the induced refractive index changes, and hence the change in the waveguide optical field due to the antisymmetric refractive index change are calculated for an elected structure. Finally, the product of switching voltage and coupling length, the power transfer efficiency, obtained using the least squares boundary residual (LSBR) method, and the optical loss due to the metal electrodes are also given.