Manipulating near field enhancement and optical spectrum in a pair-array of the cavity resonance based plasmonic nanoantennas

A 2D periodic pair-array of cavity resonance based (CRB) plasmonic nanoantennas (PNAs) on the tailoring near field enhancement and optical spectrum of surface plasmon resonance (SPR) modes is numerically investigated by using the finite element method. The CRBPNAs consist of a single cavity or double cavities in each antenna arm. Detailed physical explanations of the simulation results and consistent dependencies of the SPR features on the structural and material parameters of CRBPNAs are presented. Compared to the solid case of counterpart, the proposed CRBPNAs display outstanding SPR characteristics and tune the peak resonance wavelength by varying the outline thickness and the cavity material. In addition, the field enhancement and optical spectrum can be precisely controlled by cavity material and outline thickness in the broad band of ultraviolet, visible and near-infrared, resulting in increased sensitivity and supporting resonances with gaps and cavity surface plasmom as well as the high value of Q factors. We interpret the optical properties of the proposed CRBPNAs and show tuning and optimizing through choice of geometric and material parameters.