Tunable and large plasmonic field enhancement in core-shell heterodimer/trimer

Abstract

ABSTRACTHeterodimer/trimer are two/three closely adjacent nanoparticles dissimilar in shape or size, and represent a simple nanoscale geometry which gives rise to a remarkably rich set of properties. The core-shell nanostructure has advantages of tunability and stability over a similar homogeneous particle. We theoretically demonstrate tunable and significant field enhancement in both heterodimer and heterotrimer systems using core-shell geometry with a metal shell and dielectric core and compared our results with core-shell homodimer and homotrimer. The analytical modeling is based on the Rayleigh theory for small particles and Foldy–Lax multi-scattering theory for multiple particles. It is shown that the E-field can be enhanced in core-shell dimer/trimer due to the plasmonic resonance in the metal shell, which can be easily tunable by changing the core-shell ratio, composition of the core and shell, relative size and distance between the particles, and wavelength of the incident light. We report significant maximum field intensity enhancement near the particles. Moreover, this tunable nanostructures with high field intensity can be useful as potential bio-sensing applications.