Mid-Infrared Polaritonics in Two Dimensional Materials

Polaritons – hybrid light–matter waves emerging from the coupling of light to collective oscillations of charges –promise to enable deeply subdiffractional light manipulation. In particular, polaritons in low-dimensional van der Waals crystals boast extremely high field confinement, enabling unprecedentedly strong light-matter interactions. Moreover, the dynamic tunability of graphene plasmons facilitates the creation of a new set of active nanophotonic devices that operate at high speed. In the first part of this talk, I will discuss active metasurfaces based on graphene that operate at mid-IR frequencies, including the independent modulation of phase and amplitude of light, and dynamic angle steering of thermal emission. In the second part, I will introduce some of our near-field studies on mid-IR polaritons to manipulate their dispersion and reduce their damping. First, I will highlight the effects of the monocrystalline gold substrate on the polaritonic dispersion. Second, I will introduce bismuth and antimony chalcogenides as a new family of ultra-high-index and low-loss van der Waals dielectrics for polaritonic applications in mid-IR. Lastly, I will discuss dispersion engineering of van der Waals polaritons using a harmonically corrugated gold substrate - polaritonic Fourier crystals.