The Polarizability Vector: A Polarimetric Observable for Characterizing Anisotropic Nanoparticles

Abstract

The optical properties of anisotropic nanoparticles (NPs) are often characterized by two principal components of their polarizability tensor. However, measuring them can be demanding as the phase of the scattered field needs to be detected. To address this challenge, I reveal a novel observable, the polarizability vector, for characterizing the optical response of anisotropic NPs from a single-angle Stokes vector measurement. As I show, knowledge of grants access to pivotal nanophotonics quantities, including the scattering cross-section, optical recoil torque, and near-field amplitude. I further generalize the approach to randomly dispersed NPs, showing that, though defined at the single-particle level, fully captures their optical response. My findings pave the way for the optical characterization of anisotropic NPs using standard polarimetric instrumentation.