The optical properties of a pair of gold nanorods with slightly different plasmon resonance frequencies, i.e., detuned electrical dipoles (DED), are studied in the near-infrared. Using a multipole expansion of the induced polarization current, we argue that the transmission enhancement (transparency) at the intermediate frequency is due to the suppression of the electric dipole moment in favor of a (weakly radiating) magnetic one. This suppression is found to be robust with respect to variations in geometrical parameters, but may depend on the direction of light incidence. Metamaterials consisting of DED unit cells are examined by making use of a new homogenization method based on the numerical calculation of dispersion curves of Bloch modes, an approach that we propose and exploit for retrieving the effective material parameters. We demonstrate that DED-based metamaterials feature magnetic and bianisotropic responses, implying the important property of optical activity without chirality and opening thereby a way to new promising applications.
- Electromagnetically induced transparancy
- Optical metamaterials
- Negative index
Pors, A., Willatzen, M., Albrektsen, O., & Bozhevolnyi, S. I. (2011). Detuned electrical dipoles metamaterial with bianisotropic response. Pysical Review B, 83(24), 245409. https://doi.org/10.1103/PhysRevB.83.245409