Dark-modes excitation in coupled nano Fabry-Perot structure induced by symmetry breaking

Absorbing metamaterials have attracted a widespread interest but suffer from the metallic ohmic losses that limits their Q-factor to values around 10. In this paper, we report the engineering and experimental characterization of a high Q dark-mode in a metasurface resulting from the coupling of several individual nano-Fabry-Perot structures supporting low-contrast resonances. The resulting resonance has a Q-factor above 20 and a nearly total absorption. Moreover, we also demonstrate that several dark-mode resonances can be excited simultaneously, by exploiting the coupling of various pairs of nano Fabry-Perot resonators within the same subwavelength period. Finally, the resonance's Q-factor depends monotonously on the thickness of the metasurface and can reach values up to 85.