Fano resonance arising due to direct interaction of plasmonic and lattice modes in a mirrored array of split ring resonators.

It is demonstrated that the direct interaction of plasmonic and lattice modes can lead to Fano-type resonance in a mirrored array of simple split ring resonators. The physics behind the effect is overlapping of the frequencies of the lowest lattice mode and the broadband plasmonic mode, which plays the role of a continuum, whereas the lattice mode manifests itself as a discrete state. The overlapping is achieved by mirror symmetric orientation of two adjacent split ring resonators, which increases the lattice period twice. We have revealed that a further increase in the period of the modified array leads to a shift of the Fano resonance to a lower frequency. High quality factor of Fano resonance, around 100, has been evidenced experimentally.