Active metasurfaces and heterostructures for phase modulation and polarization conversion

Abstract

A grand challenge for nanophotonics is the realization of tunable metasurfaces enabling active control of the key constitutive properties of light – amplitude, phase, wavevector and polarization. Active metasurfaces that enable dynamic modulation of reflection amplitude, phase and polarization have been recently explored using several active materials and modulation phenomena, including carrier index in plasmonic ENZ structures, reorientation of liquid crystal molecules, electrooptic effects in quantum well heterostructures and index change in phase change materials. The rapid advances in understanding of exciton resonances in layered van der Waals materials has now stimulated thinking about active metasurfaces that exploit excitonic modulation phenomena to enable ‘van der Waals active metasurfaces. As one example, I will describe recent advances in electrically reconfigurable polarization conversion across the telecommunication wavelength range in van der Waals layered materials, integrated in a Fabry-Pérot cavity. These results have broad implications for the use of monolayer materials in active metasurfaces, and I also will give a general outlook for the wide range of possibilities for active metasurfaces based on 2D material heterostructures.