MMIC COMPATIBLE GAAS ALGAAS ELECTROOPTIC WAVE-GUIDE MODULATORS AND SWITCHES FOR MICROWAVE APPLICATIONS/

We describe the design, fabrication and measured performance of GaAs/A lGaAs p-i-n electro-optic waveguide Mach-Zehnder modulators and switch es designed to operate at frequencies up to 10 GHz. We have concentrat ed on making compact single-electrode and double-electrode (push-pull) devices using a processing method optimized to give a high yield. The modulators were made using MOCVD epitaxy, on a semi-insulating wafer, and reactive ion etching to form deep-etched guides and MMI couplers. Each device was electrically isolated by further etching, and RF conn ections were made using second-level plated metal lines over polyimide . We present results of on-wafer measured S-11 parameters against freq uency for different device designs, and demonstrate the advantages of the push-pull configuration. We also present measured S-21 parameters against frequency for a free-space optical RF link made using a push-p ull modulator.