Plasmonic mode coupling in three-dimensional metallic wire terahertz metamaterials.

In this paper, we numerically investigate the plasmonic properties of three-dimensional metallic wire-based terahertz (THz) metamaterials, with the aim of elucidating the plasmonic mode coupling within these structures. Two structures are examined: a metallic bent wire array and a woven wire mesh composed of two interwoven metallic wire arrays. Despite being composed of simple metallic wires, both systems exhibit intricate plasmonic behavior arising from the coupling of THz surface plasmon polariton (SPP) modes on the individual wires. In the bent wire array, the SPP coupling gives rise to a bound state in the continuum, and under strong coupling conditions, the system transitions to localized plasmonic modes with field enhancement factors approaching ∼10. In the woven wire mesh, the plasmonic coupling extends to the orthogonally oriented wires, enabling effective cross-guide directional coupling of wire SPPs. These results highlight the versatility of wire-based structures for applications such as THz plasmonic waveguiding, frequency filtering, and field enhancement.