OPTIMUM DESIGN OF COPLANAR WAVE-GUIDE FOR LINBO3 OPTICAL MODULATOR

In this paper, we first present a novel finite element method combined with the conformal mapping (FEM-CM) for a quasi-static analysis of coplanar waveguides (CPW), Using this approach, the optimum CPW structures for the use in the Ti:LiNbO3 optical modulator are discussed in detail to realize optical-microwave phase velocity match and electrode-source characteristic impedance match, Our numerical results reveal that both conditions can be satisfied simultaneously by introducing a SiO2 buffer layer and thicker electrodes, The modulator efficiency with respect to, the voltage-length product is also evaluated for the optimized structures, Finally, the design guidelines to the optimum CPW structure are presented.