Multiple excitation of localized surface plasmon to create a 10 nm × 10 nm strong optical spot using an Au nanoparticle array-based ridge waveguide

We present a description of a multiple excitation of localized surface plasmons (LSPs) from an Au nanoparticle (NP) array-based ridge waveguide to create a small optical spot size with an extremely strong intensity. Using a numerical finite-difference time-domain method, we find that the optical intensity of the ridge waveguide with an Au NP array is about 700% higher than that of a simple ridge waveguide. Moreover, the spacing between the NPs plays an important role in the multiple excitation of LSPs. The spot size, calculated at FWHM, is 10 nm x 10 nm at a distance of 5 nm from the exit plane.