Numerical Study of the MSCB Nanoantenna as Ultra-broadband Absorber

In this paper, we propose an ultra-broadband multi-slot cross bowtie (MSCB) nanoantenna for light absorption, whose elements compose of dual rectangles and cross bowtie and rectangular slots. The optical characteristics are analysis numerically by the three-dimensional finite-difference time-domain (FDTD) method. The results show that the average absorptivity of the nanostructure is over 90% in 400-1800-nm waveband, which covered the visible and near-infrared region. We attribute the better absorption property of the nanoantenna to the combining of plasmon coupling effects between slots, high-order modes, and surface plasmon resonance. Our work provides a promising method for the future developments of more advanced absorber for energy harvesting, thermoelectrics, and imaging.