Near- and mid-infrared plasmonic Fano resonances induced by different geometric configurations in subwavelength nanostructures

Abstract

Abstract Plasmonic Fano resonances, which result from the interaction between two plasmon modes in subwavelength nanostructures, provide a unique way to realize promising applications in light manipulation technology. Here, we investigate the infrared plasmonic Fano resonances of subwavelength periodic hole arrays with different geometric configurations in a metallic film containing Z-shaped hole arrays, cross-shaped aperture arrays, and gammadion-shaped hole arrays (GSHAs). Specifically, the infrared plasmonic Fano resonance in the GSHA structure, without considering rotational symmetry breaking, can be interpreted as stemming from the coupling between the bonding and antibonding localized surface plasmon resonance modes. By considering the rotational symmetry breaking in the GSHA structure, it is possible to actualize plasmonic double- and triple-Fano resonances in the near-infrared or mid-infrared region. Moreover, the plasmonic double- and triple-Fano resonances between the first- and second-NIR optical windows, as well as in the mid-infrared region can be controlled by appropriately regulating the related length of the arms in the GSHA structure. Our results show that infrared plasmonic Fano resonances might pave the way for the exploration of applications in optical communications and information processing.