Haomin Zeng, Chao Chang
Guiding electromagnetic waves far below the diffraction limit usually produce severe propagation loss because the field is forced into dissipative material boundaries. We discover that a metal-Epsilon-near-zero (ENZ) interface can support an optical antiskin effect, significantly reducing propagation loss by orders of magnitude while preserving subdiffraction confinement. In the proposed metal-ENZ-high-index-air (MEHA) line, a nanoscale ENZ shell suppresses the lossy surface-bound mode and pushes it above a dielectric-confined mode in the modal hierarchy, allowing the low-loss volume mode to serve as the fundamental guided state. Realistic Ag/GaAs/Si MEHA lines support a mode-reordered terahertz band with robust bend transmission. This boundary-engineering mechanism establishes a compact, bend-tolerant, low-loss metallic-waveguide platform for high-density terahertz and midinfrared integration and localized wave delivery.