Absorption enhancement and scattering inhibition for Bowtie Nanoantenna

Abstract

The nanoantennas have the distinctive ability to confine the harvested light into subwavelength dimensions by enhancing the electric field by virtue of localized surface plasmon resonance (LSPR). This work focuses on enhancing the localized field or shifting the resonance wavelength by optimizing the shape and size of the nanoantenna. The absorption and scattering properties of a bowtie nanoantenna (BNA) are enhanced by incorporating a hollow region into the parent bowtie nanoantenna. The proposed geometry of the hollow bowtie nanoantenna (HBNA) can significantly enhance the absorption and inhibit the scattering together, where the optimum operating condition can be realized by the optical gain efficient use. In the solid bowtie nanoantenna, the scattering cross-section (SCS) is more dominant (86%) than the absorption cross-section (ACS) (14%). In the proposed hollow bowtie structure, the scattered coupled power declined to 45% while the other 55% is absorbed. This design has the ability to produce the optimum plasmonic localized field enhancement in the gap of the BNA, and another design showed insensitivity to the polarization. These features can be exploited in a wide scope of applications.