The refractive-index sensitivity of metallic nanoparticles was investigated numerically using the FDTD method as well as analytically. The obtained results show that the sensitivity of nanoparticles situated in a homogeneous host matrix is independent of their shape. Moreover, it exclusively depends on the LSPR band location, the dielectric function of the metal constituting the nanoparticles, and the refractive index of the host matrix. In the case of nanoparticles deposited on a substrate or in close interaction with it, the sensitivity is however dependent on the shape. Additionally, a loss of sensitivity is observed. Different theoretical trails are examined in order to better understand those phenomena. The study emphasizes that the shape-dependent sensitivity can be related to the modification of the depolarization factors of the nanoparticles in the presence of a substrate.

In this paper, we investigate theoretically the localized plasmon resonance mode of a periodic system of bidimensional gold nanostructures coated with a dielectric layer of variable thickness. When illuminated by a plane wave in normal incidence, the interaction between the Fabry–Pérot modes established inside the layer with the particle plasmon leads to a thickness-dependent shift of the absorption maximum. Combining the Green’s tensor and finite difference time domain methods, we propose first a simple description of the physical phenomenon responsible for the wavelength shift, and then analyze the effect of the background structure refractive indexes on the characteristics of the maximum wavelength evolution.

We describe a computational approach to study the acousto-plasmonic coupling in metallic nanoparticles. We use the high level multiphysics finite element software FreeFEM developed at