ELECTRODE OPTIMIZATION FOR HIGH-SPEED TRAVELING-WAVE INTEGRATED-OPTICMODULATORS

Different electrode configurations for LiNbO3-based Mach-Zehnder trave ling-wave electrooptic modulators are analyzed, It is found that the Z -cut coplanar waveguide (CPW) configuration provides the best compromi se between the characteristic impedance, the half-wave voltage, and th e driving power, To increase the bandwidth and simultaneously reduce t he half-wave voltage, an optimum design of multisection phase reversal electrode is proposed, To verify the theoretical predictions experime ntally, two modulators, both using the Z-cut LiNbO3 CPW configuration, were fabricated and characterized, one with an optimized five-section phase reversal electrode and the other with a conventional single-sec tion electrode, By comparing the performances of these two devices, it is confirmed that significant improvements on the bandwidth to half-w ave voltage ratio and the flatness of the frequency response can indee d be obtained from using an optimized multisection phase reversal elec trode.