The objective of this research is to create a new class of Si-based electroabsorption modulators (EAM) that operate at an unprecedented bandwidth of 80Gb/s. The approach is to use 3D wafer bonding technology to vertically couple light into a nanowire high-index contrast silicon waveguide. A graded base SiGe heterojunction transistor is the baseline electric structure of the modulator, while the free carrier plasma effect is used to generate optical absorption modulation. Intellectual merits: For high capacity fiber-optic systems, a Si-based, monolithically integrated fast EAM is an appealing alternative technology to commercial III-V compound semiconductor based modulators. The proposed research will explore the carrier transport phenomena and its corresponding optical attenuation effect in a SiGe heterojuction transistor, as well as various design trade-offs among modulation depth, signal dispersion, operation speed, power consumption, and local heating effects. The proposed work will design a fully integrated modulator driver circuit using unmodified, silicon fabrication processes.
Broader impacts: An 80Gbps, low-power, and small footprint Si based EAM will be a breakthrough technology in advancing the development of the next generation of broadband fiber-optic networking and lightwave circuits for high-speed computing. There is a strong, synergistic educational and mentoring component for students at all levels. Outreach efforts will broaden participation of under-represented groups and undergraduate students in research programs at both institutions. K-12 outreach activities will be in collaboration with New York New Vision program at RPI, and through the Center for Engineering Educational Outreach (CEEO) at Tufts.