Electrode-source characteristic impedance match of CPW for LiNbO/sub 3/ optical modulators with and without ridge structure

In this paper, the characteristic impedance (Z/sub c/) analysis of the coplanar waveguide (CPW) for Z-cut Ti:LiNbO/sub 3/ optical modulators with and without ridge structure has been deduced by using the transverse resonance method (TRM), whereas the hybrid-mode analysis is carried out for CPW applicable to these structures. The analysis is based on representation of the structure as a transmission line in the Y-direction. The Maxwell's equations have been used to deduce the field distribution across the structure. Z/sub c/ as a function of the operating frequency is computed. The effect of the structure dimensions on Z/sub c/ is discussed. The microwave electric field distribution as a function of the structure dimensions is plotted. The optical properties of a LiNbO/sub 3/ optical modulator without ridge structure are also computed. Finally, the obtained results are compared with the data furnished by the literature. A good accuracy is obtained.