A multimode electrooptical switch that has high isolation between channels has been demonstrated experimentally in a 70-µm-thick plate of Z-cut LiTaO3. The fiber-compatible four-port switch is intended for integration into an optical matrix. The crosspoint consists of an in-plane crossover, two simple optical switches, and a curved connecting waveguide. For convergent input light with a 0.07 numerical aperture, 10% of the initially channeled light was transferred into the crosschannel, and the optical switching ratio of that channel was 26 dB using 450-V dc for control.
Richard A. Soref and Arthur R. Nelson, "Compound optical crosspoint with low crosstalk," Appl. Opt. 16, 3223-3229 (1977)