Full-wave analysis of traveling-wave electrodes with finitethickness for electro-optic modulators by the method of lines

In order to optimize broadband electrooptic modulators with traveling-wave electrodes, detailed information about the propagation constant, the field distribution, and the wave impedance of the modulating field is needed. To get accurate results for these characteristic values, the numerically efficient method of lines (MoL) is used. The MoL takes advantage of the planar structure by discretizing the wave equation in the directions parallel to the metallization plane, whereas an analytical formulation is retained for the transverse direction. Thus, not only the hybrid character of the modulating field but also the finite conductor thickness and anisotropy of the substrate are taken into account. Results for asymmetric coplanar stripline electrodes with typical dimensions on SiO₂ buffered LiNbO₃ are presented