Theory for the nonlinear optical response of a nonspherical metal cluster

TL;DR

This paper develops a classical electrodynamics-based theory to analyze the nonlinear optical response, specifically higher harmonic radiation, of nonspherical metal clusters of various shapes and sizes.

Contribution

It extends the existing spherical cluster theory to nonspherical shapes using a matrix formalism, enabling analysis of arbitrary shapes and complex refractive indices.

Findings

Derived sources for nonspherical particle harmonics

Developed nonlinear Mie theory for nonspherical clusters

Applicable to clusters smaller or comparable to light wavelength

Abstract

Using classical electrodynamics we determine the higher harmonic radiation by a nonspherical metal cluster in form of a matrix formalism. Extending the theory for the source of the higher harmonic radiation for spherical metal clusters as introduced by \"Ostling et al. [Z. Phys. D {\bf 28}, 169 (1993)] we calculate the sources for nonspherical particles. Employing these sources we develop the nonlinear Mie theory and determine the radiated higher harmonic fields generated by the cluster. Our theory is valid for arbitrary shape and arbitrary complex refractive index for cluster sizes much smaller and comparable to the wavelength of the incident light.