Balanced bridge modulator switch using Ti-diffused LiNbO3 strip waveguides

Abstract

An experimental integrated optical version of the Mach‐Zehnder interferometer switch, analogous to the microwave balanced bridge, is reported. The bridge is formed by 3‐μm‐wide Ti‐diffused strip waveguides in LiNbO₃ and the switch utilizes electro‐optical tuning to achieve 3‐dB operation of the directional couplers. The switching voltage required to switch between the states, corresponding to a π phase shift in one arm, equals 14.8 V. The cross talk between channels that corresponds to the extinction ratio when operated as an on‐off modulator is −21.6 dB.