Terahertz plasmonic nanotrapping with graphene coaxial apertures

Abstract

Noninvasive and noncontact approaches of trapping nanoscale biospecimens have gained extensive interest due to their biological and nanotechnological applications. Here, we have proposed a tunable plasmonic nanotweezers that works in the terahertz region, and numerically demonstrated that a deep trapping potential well for a nanoscale dielectric nanoparticle can be generated through confining and enhancing the submillimeter-scale terahertz waves into a nanogap of graphene coaxial apertures. In addition, we further show the THz plasmonic nanotweezers is capable of stable trapping a 20-nm particle with a refractive index of 1.5 while the incident waves intensity is as low as $3.5\phantom{\rule{0.16em}{0ex}}\mathrm{mW}/\ensuremath{\mu}{\mathrm{m}}^{2}$ and the photon energy is below 20 meV. It is expected that the proposed THz nanotweezers could trap and manipulate nanoscale living biospecimens via a noninvasive approach.