A Circular Dipole Nanoantenna with Improved Performance

Nanoantennas have attracted much attention because of their unique ability to collect light into subwavelength dimensions while enhancing a high electric field via localized surface plasmon resonance. Engineering the shape and size of the nanoantenna mostly focuses on improving the confined field or altering the resonance wavelength. This study focuses on improving the absorption and scattering properties of a circular-dipole nanoantenna by inserting circular holes in the two arms of the dipole. The influence of the dipole parameters on its properties such as resonance wavelength, reflection, and absorption, as well as the electric field in the gap was investigated. The proposed ring geometry can significantly increase the absorption while also inhibiting scattering, thus achieving an optimal operating state. The scattered power of a solid circular dipole nanoantenna can be up to 85%, while the remaining 15% of the incident power is absorbed. It is shown that the absorbed coupled power in the hollow circular dipole can be increased to 55%. This property results in optimal plasmonic localization of the field in the gap of the dipole nanoantenna. This finding can be deployed in photovoltaics, thermoplastics, fluorescence microscopy, and biosensing applications.