Plasmonic optical properties and the polarization modulation technique

Abstract

Surface-plasmon resonance features in nanosized gold films are studied in the Kretschmann geometry using the polarization modulation technique. The reflection coefficients R _s ² and R _p ² for the s- and p-polarized light, respectively, as well as their polarization difference Δρ = R _s ² – R _p ² are measured as functions of the angle of incidence of electromagnetic radiation, wavelength, and film thickness. Manifestations of classical and topological size effects and a qualitative model of the transition between them in nanosized gold films are discussed. It is found that the magnitude and the sign of curvature of the angular dependence of the polarization difference Δρ(θ) are related to the excitation of surface plasmons by either p-polarized light or both s- and p-polarized light in the case of homogeneous or cluster-structured metal films, respectively. It is demonstrated that nanocomposite films with gold nanoparticles embedded in a dielectric matrix can exhibit anisotropy of dielectric properties not only in the case of oblique incidence of light but also because of their macroscopically heterogeneous structure.