Enhancing optical activity by strong inter-molecular coupling. a Unit cell of a conjugated Double-Z metamaterial (CDZM). b A photograph of CDZM metamaterial composed of copper and teflon substrate. c Retrieved chirality parameters for the gap width g of 5.0, 1.0, 9.3 mm. d Chirality parameter at zero ellipticity |κ
η=0| as a function of the gap width. Adapted from Ref.