Nanotip design for high-resolution terahertz scattering-type scanning near-field optical microscopy

Terahertz (THz) scattering-type scanning near-field optical microscopy (s-SNOM) is an important means of studying and revealing material properties at the nanoscale. The nanotip is one of the core components of THz s-SNOM, which has a decisive impact on the resolution of the system. In this paper, we focus on the theory and design of the nanotip and conduct comprehensive research on it through simulation. The theoretical model is based on full-wave numerical simulation and dipole moment analysis, which can describe the overall nanotip electromagnetic response under the incident field. A comprehensive design model of nanotip geometry, sample materials, and incident field is established to significantly improve the near-field coupling efficiency and spatial resolution to achieve optimal performance.