Reduced loss of plasmon propagation along parallel silver nanowires

Surface Plasmon Polaritons (SPPs) exhibit an extraordinary ability to confine light within a subwavelength scale and have been widely used in nanophotonic devices. Whereas the energy loss associated with SPPs propagation is so severe that the transmission of optical signals through SPPs is limited. In this work, we propose a new strategy to reduce the propagation loss of SPPs in metal nanowire waveguides. We have constructed parallel nanowires (PNWs) structures with a gap distance of ~10 nm. The propagation loss of PNWs can be prominently reduced with respect to the single NW. The mechanism is attributed to mode hybridization between adjacent individual NWs, which can affect the electric field distribution and thus restrain leaky radiation to the substrate. Moreover, we have fabricated distinct PNWs structures to compare their propagation losses. The finite element method (FEM) has been used to calculate field distributions of plasmon modes and study the effect of gap distance, demonstrating a high figure of merit (FoM) waveguiding by exploiting the coupling between PNWs. Our work provides a new road to reduce the propagation loss of SPPs along metal NWs, which is crucial for the applications of plasmon-based nanophotonic devices.