Nano-Scale THz Wave Propagating with Ultra-Low Loss

A metal nanowire placed in a dielectric hole is proposed to guide THz modified surface plasmon polaritons (MSPPs). In theory, the MSPP waveguide can guide THz wave with nano-scale mode width (570 nm) and simultaneously ultra-long propagation distance (2.4 m). Compared with conventional surface plasmon polaritons (SPPs) on a bare metal nanowire, the MSPPs' mode nanoconfinement can be maintained by keeping a part of the mode field nearly unchanged. On the other hand, by modifying the rest of the mode field, the THz power inside the metal nanowire can be significantly reduced for MSPPs, which dramatically decreases the propagation loss (3 orders of magnitude).