Multipole optimization of light focusing by silicon nanosphere structures

TL;DR

This paper presents an analytical and numerical approach to optimize silicon nanosphere structures for light focusing, demonstrating the potential for designing ultra-thin metalenses with predefined properties.

Contribution

It introduces a coupled multipole model combined with the zero-order Born approximation and evolutionary algorithms for designing silicon nanosphere metalenses.

Findings

Analytical approximations agree with T-matrix numerical simulations.

Optimization significantly improves focusing properties of silicon nanosphere structures.

The method shows strong potential for engineering ultra-thin metalenses.

Abstract

We investigate the applicability of the coupled multipole model and its modification in the framework of the zero-order Born approximation for modeling of light focusing by finite-size nanostructures of silicon nanospheres, supporting electric and magnetic dipole and quadrupole resonances. The results based on the analytical approximations are verified by comparison with the numerical simulations performed by the T-matrix method. Using the evolutionary algorithm optimization, we apply the developed approach to design the silicon nanosphere metalenses with predefined focusing properties. The obtained results demonstrate a strong optimization potential of the suggested calculation scheme for engineering ultra-thin metalenses.