Resonant unidirectional and elastic scattering of surface plasmon polaritons by high-refractive index dielectric nanoparticles

TL;DR

This paper demonstrates how high-refractive-index dielectric nanoparticles can resonantly and unidirectionally scatter surface plasmon polaritons and light, enabling advanced control in plasmonic and photonic devices.

Contribution

It reveals the role of bianisotropy in resonant unidirectional and elastic scattering of SPPs by dielectric nanoparticles on a metal substrate.

Findings

Resonant unidirectional scattering of SPPs achieved within a narrow spectral range.

Significant suppression of SPP excitation due to destructive interference.

Electric and magnetic dipoles can be excited simultaneously at the same wavelength.

Abstract

We consider scattering of surface plasmon polaritons (SPPs) and light by individual high-refractive-index dielectric nanoparticles (NPs) located on a metal (gold) substrate and supporting electric and magnetic dipole resonances in the visible spectral range. Numerical calculations are carried out by making use of the discrete dipole approximation including the multipole decomposition procedure. Extinction and scattering cross section spectra of spheroid silicon NPs in visible and near-infrared are presented and discussed. The roles of the in-plane and out-of-plane components of electric and magnetic dipoles in the scattering processes are clarified and demonstrated. It is revealed that, owing to the NP interaction with electromagnetic fields reflected from the substrate (that leads to bianisotropy), the in-plane electric and magnetic dipoles can resonantly be excited at the same wavelength. Due to this effect, the resonant unidirectional (forward) and elastic (in-plane) scattering of SPPs by oblate spheroid NPs can be realized within a narrow spectral range. In the case of normal light incidence, the bianisotropy effect can provide significant suppression of the SPP excitation because of the destructive interference between the SPP waves generated by induced electric and magnetic dipole moments. The results obtained open new possibilities for the Development of SPP-based photonic components and metasurfaces, whose operation involves resonant excitations of dielectric NPs.