Transverse spin in scattering of focused radially and azimuthally polarized vector beams

TL;DR

This paper investigates how focusing radially and azimuthally polarized vector beams affects the transverse spin angular momentum density and Poynting vector of scattered waves from a Mie particle, revealing unique transverse spin properties.

Contribution

It demonstrates that the scattered field's SAM density is purely transverse for these beams and shows how to tune this transverse SAM via wavelength and focusing, advancing understanding of spin-momentum in scattering.

Findings

SAM density is purely transverse in scattered fields

Poynting vector remains longitudinal despite transverse SAM

Transverse SAM can be tuned by wavelength and focusing

Abstract

We study the effect of focusing of the radially and azimuthally polarized vector beams on the spin angular momentum (SAM) density and Poynting vector of scattered waves from a Mie particle. Remarkably, the study reveals that the SAM density of the scattered field is solely transverse in nature for radially and azimuthally polarized incident vector beams; however the Poynting vector shows usual longitudinal character. We also demonstrate that the transverse SAM density can further be tuned with wavelength and focusing of the incident beam by exploiting the interference of different scattering modes. These results may stimulate further experimental technique of detecting the transverse spin and Belinfante's spin-momentum densities.