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

In this paper, the characteristic impedance (Z_c) analysis of the coplanar waveguide (CPW) for Z-cut Ti:LiNbO₃ 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_c as a function of the operating frequency is computed. The effect of the structure dimensions on Z_c is discussed. The microwave electric field distribution as a function of the structure dimensions is plotted. The optical properties of a LiNbO₃ 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