Analysis and Design of Reflective Nonlinear Metasurfaces Incorporating 2D Materials Utilizing a Multimode Quasi-Normal Mode Framework for Non-Hermitian Systems

A nonlinear graphene reflective metasurface for third-harmonic generation in the THz band is presented. The proposed metasurface is analyzed and designed using a multimode framework for non-Hermitian systems incorporating 2D materials that is based on the concept of quasi-normal modes (QNMs) and can correctly estimate both linear and nonlinear responses of the metasurface. The conducted analysis using the QNMs framework allows for the correct encapsulation of the involved physics and the multimode interactions that mediate the complex frequency response of the metasurface and the process of the nonlinear frequency generation.