Small AC Driving Voltage for MZI-Based GaAs–GaAlAs Electrooptic Modulators/Switches With Coplanar Electrodes

We report a method to achieve a small ac driving voltage for high-speed multimode interference Mach-Zehnder interferometer GaAs-GaAlAs electrooptic modulators and switches with coplanar electrodes for polarization-insensitive operation. By biasing the devices in the reverse break-down region, the ac driving voltage can be as small as 3 V. Such a small ac driving voltage is important for high-speed optical modulators and switches. The physics behind this small ac driving voltage is also discussed.