Optical properties of plasmonic components based on a nanoscale three-dimensional plasmonic waveguide

In this paper, the properties of five kinds of passive nanoscale optical devices (including directional coupler, waveguide ring resonator, add-drop filter, nano light focusing device, and Mach-Zehnder interferometer, etc.) based on a new nanoscale three-dimensional plasmonic waveguide the authors proposed previously are presented. For the proposed nanoscale optical directional coupler, the coupling length does not show monotonic increase with the increase of edge-to-edge distance between two waveguides, and thus there exists an optimal edgeto-edge distance of around 0.1 mu m with a minimum coupling length of about 2.7 mu m and high coupling efficiency of 93.4%. And the waveguide ring resonator with a very small ring radius of 1.1 mu m and a separate gap of 80 nm features an extinction ratio as small as 2.9%, with large free spectral range of 194 nm, and a bandwidth of 24 nm. Moreover, an add-drop filter with the same ring radius of 1.1 mu m and a separate gap of 80 nm features a 24.4% extinction ratio. The optical properties of the devices are numerically investigated by the finite-difference time-domain simulation method. These excellent properties make them have great potential in nanophotonic integrated circuits. (C) 2019 Optical Society of America