Dynamic light manipulation with atomically thin metasurfaces

In the field of optics, we are used to direct and control light waves with bulky optical components, such as a glass lens. The recent development of metasurfaces has brought many exciting new ways to manipulate the flow of light. These are essentially flat optical elements comprised of dense arrays of nanostructures that can cleverly harness light scattering and interference effects to redirect and control light waves. The ultimate physical limitations of these optical components can be traced back to the properties of the materials and building blocks that they are constructed from. Current metasurface designs largely employ metallic (e.g. gold and silver) or high-index semiconductor (e.g. silicon or titanium dioxide) nanostructures. They afford strong light scattering because they support geometry and size-dependent optical resonances. However, emerging metasurface applications in quantum optical communications, augmented reality, non-linear optics, and spatiotemporal light control demand much more than the basic, linear, and typically-static scattering responses provided by these conventional materials and nanostructures. In this presentation, I will ask the question whether the materials resonances of atomically-thin quantum materials can be harnessed to create conceptually new types of metasurfaces with improved performance and radically new functionalities.

At the core of the operation of the proposed, atomically-thin metasurfaces are strong, intrinsic materials resonances that can deliver a light-matter interaction that is unparalleled in its strength and tunability. To effectively capitalize on such resonances, it is important to deeply understand how they arise from the electronic bandstructure of two-dimensional (2D) materials and the ways their strength can be impacted by unwanted processes, such as non-radiative decay and dephasing processes as well as defects and disorder. I will also demonstrate that a careful engineering of the materials strain and photonic environment can be used to mitigate the unwanted processes and enhance the metasurface performance at room temperature.