Fano-Feshbach resonance in structural symmetry broken metamaterials

Metamaterials support optically excitable dark-plasmon modes featured by antisymmetric surface current oscillations, which can be explained by Fano-type resonance and can be tailored by controlling the embedded structural geometry. In this article, we numerically investigate the Fano-type resonance in complex metamaterials, and demonstrate the presence of Fano-Feshbach resonances due to the interaction between two Fano-type resonances in the overlapping region, implemented by breaking and tuning the symmetric properties of the resonant metallic element. Features of the resonance are discussed. This work shows that the domain of dark-plasmon mode based metamaterial system supports rich physics and can lead to various potential applications. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3528208]