Magnetic-electric interference in metal-dielectric-metal oligomers: generation of magneto-electric Fano resonance

The existence of magnetic resonance in designed Metal-Dielectric-Metal (MDM) oligomers is investigated. Via angling the incident light it is found that in the MDM oligomers, not only the E-component of incident field drives plasmon oscillations, but the H-component also plays an important role to excite magnetic plasmons. These magnetic plasmons give rise to a magnetic resonance in addition to classical Fano Resonance (FR). Importantly, unlike regular MDM structures which exhibit separate magnetic and electric resonances, the MDM oligomers possess the capability to exhibit both magnetic and electric resonances in the same wavelength window with proper metallic and dielectric thicknesses. It leads to the appearance of an additional FR as a result of interference between magnetic-electric plasmonic resonances rather than electric-electric resonances with a clear proof of remarkable absorption enhancement. The unique capability of MDM oligomers exhibiting both electric and magnetoelectric FRs can realize many potential applications of FR. (C) 2012 Optical Society of America