Multiple Fano resonances in metallic arrays of asymmetric dual stripes.

Characteristics of Fano resonances in metallic arrays of asymmetric dual stripes are theoretically investigated. The structure consists of two perfect metal stripes with unequal sizes in a unit cell. In addition to the total reflection that usually occurs in single-stripe arrays, the dual-stripe arrays exhibit two extra pairs of reflection peaks and dips, which are identified as the Fano resonance with the reflection line shape characterized by a Fano formula. In particular, the peak-dip pair on the high-frequency side is recognized as the high-order Fano resonance, as compared to its counterpart on the low-frequency side. Features of the Fano resonances are further illustrated with the electric field and surface current patterns at the corresponding frequencies. The underlying mechanism of multiple Fano resonances in the dual-stripe arrays is also discussed.