Metallic Nanowire-Loaded Plasmonic Slot Waveguide for Highly Confined Light Transport at Telecom Wavelength

The optical properties of a plasmonic slot waveguide that comprises a metallic nanowire supported by a thin-dielectric-coated metal surface are investigated at the telecom wavelength. The fundamental plasmonic mode sustained by the waveguiding configuration is shown to be strongly confined inside the gap between the nanowire and the metallic substrate, along with moderate propagation loss and deep-sub-wavelength mode size achievable simultaneously. Studies on the effects of key geometric parameters on the modal properties reveal that the tradeoff between confinement and loss could be well controlled through tuning the dimensions of the nanowire and the gap. Through conducting 3-D numerical simulations, we further show that its guided plasmonic mode can be directly excited using similar strategies to those of the plasmonic nanowire mode. The nice optical performance, in conjunction with significant field enhancement inside the nanoscale low-index gap region, could facilitate potential applications in sensing, nonlinear light processing, optical manipulation as well as the implementations of numerous ultra-compact passive, and active nanophotonic devices.