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‐&mgr;m‐wide Ti‐diffused strip waveguides in LiNbO3and 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 &pgr; 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.