The routing of data electronically within microprocessors is becoming increasingly challenging due to the large volumes of data being transferred. Optical interconnects on silicon are an attractive alternative to traditional electronic interconnects because they provide higher bandwidth and have the potential to be compatible with low cost, high volume, mature CMOS processing. Recent efforts in silicon photonics have focused on developing a wide range of optical components, such as lasers, amplifiers, photodetectors, that can be integrated on a single platform. Among all, a lot of work has focused on modulators as they are crucial for the generation and transmission of high-speed signals such that increasing demands on data capacity can be satisfied.

In this work, a hybrid silicon modulator based on a Mach-Zehnder interferometer architecture is developed to efficiently send large amount of information with large optical bandwidth, high-speed operation and good modulation efficiency. The tradeoff between modulation efficiency and speed in pure silicon can be overcome by utilizing the hybrid silicon platform, where the carrier depletion effect inside the III-V materials is introduced to create index shift. The demonstrated device has a voltage-length product of 2.5 Vmm and 20 dB extinction ratio. Moreover, the modulation bandwidth can be promoted to a higher regime by employing a capacitively loaded traveling-wave electrode design. With the developed techniques, we successfully demonstrate a high-speed modulator with 25 GHz bandwidth and 10 dB extinction ratio at 40 Gb/s. In addition, a 2x2 hybrid silicon switch, which is a candidate for large-scale optical network, is also reported based on the developed architecture with 0.5 dB power penalty at 40 Gb/s. The application can be further extended to an integrated level by establishing a microwave tunable filter using thermal modulators and amplifiers on the hybrid silicon platform. The details of the design, fabrication, and characterizations of the aforementioned devices will be presented.