PhD Defense: "High-Speed Hybrid Silicon Mach-Zehnder Modulator and Tunable Microwave Filter"

Hui-Wen Chen

January 28th (Friday), 2:00pm
ESB Rm 2001

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 modulator based on a Mach-Zender interferometer (MZI) is developed on the hybrid silicon platform. The platform consists of a III-V layer that is bonded to silicon. The tradeoff between modulation efficiency and speed in pure silicon can be overcome by utilizing the hybrid silicon platform, because the more pronounced carrier depletion effect inside the III-V materials is exploited to create the required index shift. The demonstrated device has a voltage-length product of 2.5 Vmm and 20 dB extinction ratio. The modulation bandwidth of the device can be increased by employing a capacitively loaded traveling-wave electrode design. Implementing such an electrode design, we successfully demonstrate a high-speed modulator with 25 GHz bandwidth and 10 dB extinction ratio at 40 Gb/s. Additionally, we show the applicability of the developed modulator in realizing a range of components for both digital and analog communications. In the digital domain the modulator is used in a 2×2 optical switch and is shown to have 0.5dB power penalty at 40Gb/s. It has the potential to meet the stringent energy and power switching constraints of future optical networks. In the analog domain, the modulator is integrated with amplifiers and other passive components on the hybrid silicon platform to realize a tunable microwave filter. The details of the design, fabrication, and performance of the aforementioned devices will be presented.

About Hui-Wen Chen:

Hui-Wen Chen received her B.S. in Electrical Engineering in 2003 and M.S. in Communication Engineering in 2005 from National Tsing Hua University (NTHU) and Naitonal Chiao Tung University (NCTU) respectively. Her interest includes design, fabrication, and characterization of high speed MZI modulators and switches on the hybrid silicon platform.

Hosted by: Professor John Bowers