Anisotropic properties of plasmonic nanoparticles: depolarized light scattering, dichroism, and birefringence

The properties of gold and silver nanorods and nanodisks with geometric parameters typical of wet chemical fabrication protocols were investigated. With an extended-precision T-matrix code, a representative set of simulations for extinction, light scattering, and depolarization ratio spectra of randomly oriented particles and for dichroism and birefringence spectra of particles with an arbitrary predominant orientation with respect to incident linearly polarized light were obtained. The appearance of ultra-depolarized light scattering from random ensembles was elucidated by several 3D maps illustrating the dependence of the depolarization ratio on particular orientations of rods and disks. A simple dipole model sufficed to explain the orientation dependence of dichroism and birefringence and the unusual invariant spectral localization of the depolarization ratio maxima. Reasonable agreement was obtained with experimental data on depolarized light scattering from gold nanorods.