# Scattering of light with angular momentum from an array of particles

## TL;DR

This paper explores how beams with orbital angular momentum can be used to detect and distinguish structured particle distributions in disordered media, with implications for communications and particle analysis.

## Contribution

It introduces a generalized Mie theory approach to analytically calculate light scattering with angular momentum from particle arrays, enabling detection of particle arrangements.

## Key findings

- Structured particle distributions can be distinguished from random ones using OAM beams.
- Signal-to-noise ratio is consistent across Laguerre-Gaussian modes in dense dilute media.
- The method enables multiplexed signal encoding using angular momentum states.

## Abstract

Understanding the scattering properties of various media is of critical importance in many applications, from secure, high-bandwidth communications to extracting information about biological and mineral particles dissolved in sea water. In this paper we demonstrate how beams carrying orbital angular momentum (OAM) can be used to detect the presence of symmetric or chiral subsets of particles in disordered media. Using a generalized Mie theory we calculate analytical expressions for quasi-monochromatic structured light scattered by dilute distributions of micro- and nanoparticles. These allow us to determine the angular momentum of the scattered field as a function of the angular momentum of the incident beam and of the spatial distributions of scattering particles. Our numerical results show that we can distinguish structured from random distributions of particles, even when the number density of ordered particles is a few percent of the total distribution. We also find that the signal-to-noise ratio, in the forward direction, is equivalent for all orders of the Laguerre-Gaussian modes in relatively dense (but still dilute) distributions, making them an ideal basis to encode and transmit multiplexed signals.