Dynamic Control of Nonlinearly Generated Light Chirality with Nanostructured Graphene

The constant development of nanotechnology has facilitated significant improvements in the field of nonlinear optics. Metasurfaces and metamaterials, or nanostructured material systems, have allowed excellent control over a variety of linear and nonlinear optical processes, including manipulation of the amplitude, phase, and polarization of light. To facilitate this progress, there is an increasing demand for small footprint nonlinear material systems and metamaterial designs that offer diverse functionalities. Here, we demonstrate that this demand can be satisfied by utilizing the family of two-dimensional materials and more specifically graphene. In this work, we take advantage of the exceptionally large nonlinearity of graphene and demonstrate simultaneous dynamic control over the polarization state and nonlinear conversion efficiency of the third harmonic emission via the coherent excitation of localized surface plasmons in nanopatterned graphene rectangular arrays. Using finite-difference time-domain simulations and through electrostatic control over the Fermi level in graphene, we demonstrate broadband dynamic tuning between linear and circular polarization states for the third harmonic emission. The proposed method is not limited to third harmonic emission and is applicable to different nonlinear optical processes. As a result, the proposed metasurface constitutes an outstanding platform for commercially viable, CMOS-compatible, room-temperature devices for nonlinear conversion applications.