Our research generally aims to create photonic
and electronic devices having useful and non-intuitive functionalities, by exploring the intersections of
optics, solid state physics, and other fields of physics at the nanoscale. We tackle fundamental problems
in plasmonics, metamaterials, and electron-optics, motivated by practical applications in imaging, sensing,
information processing, and energy devices.
Specific areas of current interest include:
Graphene is an interesting material for active nanophotonics. Recent studies have shown that the effective optical index of graphene depends on the local Fermi level, which can be varied greatly via electrostatic gating techniques. More interestingly, the low carrier concentration and the atomic thinness of graphene allows for highly confined plasmonic modes whose properties are also widely tunable as a function of doping density. These tunable plasmonic modes offered by graphene and other 2D materials provide new opportunities to create electo-optically active devices with novel functionalities that have thus far been impossible to be realized by using conventional media. Our research topics include:
Light absorption in plasmonic nanostructures is inevitable, and often viewed as a detrimental consequence of using metals to control light at optical frequencies. Although plasmonic structures have been widely used in energy and sensing applications because of their ability to localize and trap light, the light absorbed in those plasmonic structures themselves, however, have been wasted and therefore simply considered as loss. Only recently researchers have begun to think about possible uses of plasmon-induced hot carriers. We are investigating opportunities to utilize plasmonic absorption in practical applications with emphasis on the uses of plasmon-induced heat.
Electrons in graphene behave like massless Dirac fermions with linear dispersion relation similar to photons, and can propagate coherently over large distances of the order of microns. This optics-like dispersion enables making analogy between optics and graphene electronics, namely electron optics. The electronic equivalents of photonic devices such as lenses and waveguides have been proposed in recent years. We are exploring possiblities of transferring interesting scientific achievements in photonics, such as transformation optics and resonant guided wave networks, to graphene electronics.