Terahertz plasmonic nanotrapping with graphene coaxial apertures

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 3.5mW/µm2 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.