CAREER: Doped Graphene: a Transformative Paradigm for Plasmonics and Two-Dimensional Nanophotonics
Doped graphene, a one-atom-thick but highly conductive sheet, provides us with an unprecedented platform to explore surface plasmon and two-dimensional optics in a regime that can hardly be obtained with noble metals or conventional electron gases. Theoretical calculations show that graphene surface plasmon (transverse magnetic mode) shows extraordinarily tight confinement and short wavelength. Graphene also supports a new type of surface electromagnetic wave (transverse electric mode). Furthermore, as a material with tunable permittivity, graphene holds promise for integrated two-dimensional active photonic devices. Despite the great potential of graphene, there is clearly a lack of direct experimental confirmation of surface plasmon as well as demonstration of active plasmonic devices.
The long-term goal of this research is to reveal experimentally many unusual properties of graphene surface plasmon and to develop next-generation novel nanophotonic devices. Specifically, we will investigate localized surface plasmon resonances in chemical-doped graphene nanostructures, employ Otto configuration to explore TE surface plasmon, and develop a pump-probe space-time-resolved spectroscopy method to study terahertz surface plasmon polaritons. We will then demonstrate three active photonic devices: terahertz surface plasmon modulators, tunable terahertz Mach-Zehnder interferometers, and dynamic infrared frequency-selective surfaces.
Intellectual Merit: This research addresses the current needs and challenges of graphene plasmonics. Experimental demonstration of localized and propagating surface plasmons will not only position graphene as a novel plasmonic material, but it also opens a new field for plasmonics research. The development and demonstration of the proposed active plamsonic devices further will provide a basic understanding of manipulating light on a two-dimensional surface, paving the way for advanced applications of graphene as an active metamaterial. The techniques developed in this research will also become valuable tools of the plasmonic community for future exploration of graphene plasmonics.
Broader Impacts: The proposed research is transformative in that it enables the development of a range of novel photonic devices with integration and functionality that cannot be achieved with conventional materials. For example, the extremely tight confinement of light and strong local electrical field make it possible to observe novel quantum phenomena, such as vacuum Rabi splitting, and enable applications such as surface-enhanced Raman scattering, enhanced light harvesting for efficient solar cells, and ultrahigh-resolution optical microscopy. An active frequency-selective surface has applications in smart cloaking for defense and secure wireless communication. Finally, the ability to control light on a surface at nanoscale dimensions will revolutionize the photonic industry and information technology by providing ultrasmall photonic devices and integrated electronic-photonic circuits, ultimately leading to superfast computing and information processing.
This program integrates cutting-edge research with education, providing a broader education opportunity for one of the most diverse student body in the nation. The existing effort includes integration with the UH-based NSF REU, RET, and STEP programs and participation in high school science fairs. To further disseminate knowledge obtained from the proposed research and to enhance the recruitment of women and underrepresented minorities into the field of nanoscience and nanotechnology, the PI will revise the current graduate-level solar cell program into a dual-level course covering nanotechnology and renewable energy for graduates and undergraduates majoring in our Nanoengineering Minor Option. The PI will also organize a one-day graphene summer camp for students from the Harmony Academy of Science, as well as sponsor their research in the next few months on graphene-based green energy technology, which will be presented at the annual I-SWEEEP (International Sustainable World Energy, Engineering & Environment) Olympiad.