Discrete sources method for investigation of near field enhancement of core-shell nanoparticles on a substrate accounting for spatial dispersion

Abstract

Quantum nanoplasmonics attracts increasing interest of researchers since its innovations have great potential for practical applications. Over the past decades, the use of core-shell nanoparticles has gained huge popularity due to the ability to manipulate the materials and sizes of both core and shell to control their plasmonic properties. This circumstance favorably distinguishes them from its homogeneous counterparts. In this paper, based on the Discrete Sources Method, we investigate the effect of spatial nonlocality in a metal shell of a nonspherical core-shell nanoparticle deposited on a glass prism. Our primary goal is to examine the impact of the nonlocal effect on the near-field enhancement and the absorption cross section of the particle. We found that accounting for the interaction of a particle with a prism has a larger influence on the optical characteristics of the near field than on the intensity in the far zone. For excitation of the core-shell particle, both a propagating and an evanescent wave, have been considered. It was found that evanescent wave excitation provides a larger near field enhancement than an exciting propagating wave. Taking into account the nonlocality effect in the metal shell leads to a significant damping of the plasmon resonance amplitude accompanied by a small blue shift.