Graphene is a monolayer of carbon atoms constructing a two-dimensional honeycomb structure, and it has an excellent carrier mobility and a very high thermal conductivity. Recently, Recently, graphene based optical modulators and phase shifters have emerged as an area of intense research partly due to the ability of confined graphene plasmonic resonances to create a strong electrostatic response at THz to mid-IR frequencies. Additionally, the high confinement factor of graphene plasmons allow for the creation of highly miniaturize and active optical elements. Despite these capabilities, the poor radiative coupling to graphene plasmonic nanoresonators and low graphene carrier mobilities from imperfections in processed graphene samples have led to low light modulation depths in experimental attempts at creating tunable light modulation in graphene devices. In this talk, I will present three strategies to efficiently modulate mid-infrared light using graphene plasmonic nanoresonators coupled with noble metal plasmonic structures. Here, noble metal plasmonic structures are utilized to significantly enhance light-matter interactions in graphene, which creates larger light modulation depths in graphene plasmonic devices. First, experimental demonstration of perfect absorption in graphene will be discussed. The proposed devices show that perfection absorption in graphene is no longer limited by low graphene carrier mobility, which leads to 100% modulation efficiency in a reflection type light modulator. Next, a strategy for enhancing the tunability of transmission type light modulators will be discussed. To achieve this, resonant absorption in graphene plasmonic nanoresonators are exploited to suppress extraordinary optical transmission resonance in noble metal structures. Finally, I will present energy transport along graphene plasmonic nanoresonators, and a device design to modulate light in noble metal plasmonic waveguides.
Seyoon Kim received his B.S. degree and M.S. degree in electrical engineering from Seoul National University in 2005 and in 2007,
respectively. He was a researcher at Agency for Defense Development from 2007 to 2008 and at Seoul National University from 2008 to 2010.
After receiving his Ph. D. degree from California Institute of Technology in 2016, he now works at ICFO in Spain as a postdoctoral
researcher. His research interests include graphene plasmonic light modulators and metasurfaces.