Effect of the buffer layer on the microwaves properties in the coplanar waveguide for LiNbO/sub 3/ optical modulators with superconducting electrodes

The effects of a buffer layer on the modulation bandwidth of LiNbO/sub 3/ optical modulators with superconducting and normal-conducting electrodes have been deduced by using the transverse resonance method (TRM). The analysis is based on the integral equations and the equivalent network representation of each structure. A high Tc superconducting material Yba/sub 2/Cu/sub 3/O/sub 7-8/ (YBCO) has been used for the super-conducting electrode case. The microwave effective index (N/sub m/) as a function of the thickness and dielectric constant of the buffer layer has been computed. Also the bandwidth-length product (/spl Delta/f.L) as a function of the thickness and dielectric constant of the buffer layer has been computed. A comparison with published results is also included to check the accuracy of TRM technique's results.