Transverse spin and transverse momentum in scattering of plane waves

TL;DR

This paper investigates how the transverse components of spin angular momentum and Poynting vector evolve from near to far fields in scattering by spherical particles, revealing controllable enhancement mechanisms.

Contribution

It demonstrates the independence of transverse SAM from incident helicity and shows how interference of scattering modes can enhance transverse momentum components.

Findings

Transverse SAM density is helicity-independent.

Transverse Poynting vector depends on polarization.

Interference of modes enhances transverse components.

Abstract

We study the near field to the far field evolution of spin angular momentum (SAM) density and the Poynting vector of the scattered waves from spherical scatterers. The results show that at the near field, the SAM density and the Poynting vector are dominated by their transverse components. While the former (transverse SAM) is independent of the helicity of the incident circular polarization state, the latter (transverse Poynting vector) depends upon the polarization state. It is further demonstrated that the magnitudes and the spatial extent of the transverse SAM and the transverse momentum components can be controllably enhanced by exploiting the interference of the transverse electric and transverse magnetic scattering modes.