Design of a High-Bandwidth Traveling-Wave III-V/Si Hybrid MOS Optical Modulator

The III-V/Si hybrid Metal-Oxide-Semiconductor (MOS) optical modulator is promising for high-efficiency, low-energy and high-speed optical modulation. As of now, all the IIIV/Si hybrid MOS optical modulators demonstrated were driven by the RC-limited lumped electrodes. In order to break the RC limitation posed by the driving scheme, we designed a traveling-wave III-V/Si hybrid MOS optical modulator. Based on the equivalent circuit model developed, the traveling-wave electrode geometry, doping concentration and equivalent oxide thickness were optimized numerically to achieve the velocity and impedance matching for high modulation bandwidth with a low V-pp of 2 V. High modulation bandwidths of 75 GHz and 102 GHz were predicted for carrier-accumulation mode and carrier depletion mode, respectively. The expected high modulation bandwidth makes the III-V/Si hybrid MOS optical modulator more attractive in the high-data-rate optical transmission.