Frequency-dependent propagation characteristics of coplanar waveguide electrode on 100GHz Ti:LiNbO/sub 3/ optical modulator

摘要

The microwave propagation characteristics of a coplanar waveguide electrode in the frequency range 45 MHz-110 GHz were studied in order to evaluate the factors which limit the performance of a high-speed ridged Ti:LiNbO/sub 3/ optical modulator. Since the effective microwave index is constant in the higher frequency range, neither structure nor material dispersions of the modulator are observed. In addition to the conductor loss, the dielectric loss also increases above 20 GHz. The dielectric loss is shown to originate not only in the LiNbO/sub 3/ substrate, but also in the silicon oxide buffer layer.