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 $3.5\mathrm{mW}/\mu {\mathrm{m}}^2$ 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.

• Received 21 June 2020
• Accepted 19 October 2020

DOI:https://doi.org/10.1103/PhysRevA.102.053507

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