Silicon photonics is a rapidly growing industry, potentially reaching an annual value of over a billion dollars in the coming decade. In parallel, the complexity of photonic integrated circuits has increased by more than an order of magnitude. The optical response of silicon at wavelengths used for telecommunications, however, is relatively weak. Current optoelectronic technologies therefore rely on integrating other materials with the desired properties. In this context, graphene has emerged as an excellent candidate to realize silicon-compatible optoelectronic devices. Graphene is an atom-thick, two-dimensional material made from carbon. It is nearly 100 times stronger than steel, conducts heat and electricity efficiently, and has unusual optical properties. Recent experimental reports have already approached the predicted performance limits of graphene-based devices. It is not obvious how the device performance can be further enhanced while simultaneously reducing device size. Thus, new paradigms in graphene-based optoelectronic devices are required. This project will develop a new approach for realizing integrated optoelectronic devices. Nanofabrication will be used to integrate graphene into active devices and engineer the effective optical properties with nm scale resolution. These devices will be fully compatible with CMOS technology and promise dramatic reductions in device footprint and losses, while providing fast-speed with low energy consumption. The project brings together a multidisciplinary team of researchers from the United States, Northern Ireland, and the Republic of Ireland through the NSF-US/Ireland R&D Partnership. International cooperation will provide exceptional opportunities for international student exchange and research collaboration as part of this project.
The proposed work aims to develop a new family of graphene-based CMOS-compatible optoelectronics. The two premises behind the proposed approach are that: (i) via nanofabrication, it is possible to spatially engineer the local refractive index of the device at deep sub-wavelength dimensions; and, (ii) by integrating two-dimensional material layers, it is possible to provide active functionality in a reduced area. The operation of these devices relies on the coupling between a number of resonant nano-photonic modes, which does not only make them robust to fabrication errors but also enables broad optical bandwidth in a reduced footprint. Three main research thrusts are identified: (a) development of high-performance ultra-compact graphene electro-optic modulators. (b) Extension of the proposed design concept to other optoelectronic devices beyond modulators (e.g., phase shifters, active couplers, polarizers, and sensors). (c) Monolithically integrate multiple devices on an optical chip and drive with proper CMOS circuitry. The proposed research is highly transformative since it combines two emerging research concepts so to overcome the main limitations of current integrated optoelectronic technologies.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
