Multipole Born series approach to light scattering by Mie-resonant nanoparticle structures

TL;DR

This paper introduces a modified Born series approach within the coupled multipole method to analytically simulate light scattering by Mie-resonant nanoparticle structures, improving understanding of physical processes and convergence conditions.

Contribution

It develops an analytical Born series-based modification of the coupled multipole method for simulating light scattering in complex nanoparticle structures, including dipole and quadrupole resonances.

Findings

The modified approach accurately models scattering by nanosphere structures.

Convergence conditions of the Born series are established.

Physical factors affecting convergence and accuracy are analyzed.

Abstract

Exciting optical effects such as polarization control, imaging, and holography were demonstrated at the nanoscale using the complex and irregular structures of nanoparticles with the multipole Mie-resonances in the optical range. The optical response of such particles can be simulated either by full wave numerical simulations or by the widely used analytical coupled multipole method (CMM), however, an analytical solution in the framework of CMM can be obtained only in a limited number of cases. In this paper, a modification of the CMM in the framework of the Born series and its applicability for simulation of light scattering by finite nanosphere structures, maintaining both dipole and quadrupole resonances, are investigated. The Born approximation simplifies an analytical consideration of various systems and helps shed light on physical processes ongoing in that systems. Using Mie theory and Green's functions approach, we analytically formulate the rigorous coupled dipole-quadrupole equations and their solution in the different-order Born approximations. We analyze in detail the resonant scattering by dielectric nanosphere structures such as dimer and ring to obtain the convergence conditions of the Born series and investigate how the physical characteristics such as absorption in particles, type of multipole resonance, and geometry of ensemble influence the convergence of Born series and its accuracy.