Analysis of a coplanar waveguide with finite metallization thickness on an anisotropic multilayer substrate using method of lines

Coplanar waveguides (CPWs) have been proposed and used for the external modulation and control of lightwaves at microwave frequencies. To achieve the GHz modulation bandwidth, travelling wave configurations are more convenient. The design and optimization of such structures require accurate microwave characterization of CPWs in terms of phase velocity, characteristic impedance, and attenuation. The appropriate analytical or numerical method for this purpose should take the finite metallization thickness and loss as well as the anisotropy of the substrates with high electro-optic sensitivities into account. Taking advantage of the uniformity of the structure in lateral directions (perpendicular to the lamination) we chose the method of lines (MOL) as an optimum approach to analyze this structure. Numerical stability, computational efficiency, and the possibility of modeling of realistic geometries are the main advantages of this method compared to other techniques for our problem. We apply this method to a thick CPW line on an anisotropic multilayer substrate.