Optical mirages from spinless beams

TL;DR

This paper reveals that optical mirages can occur under spinless illumination due to electric and magnetic dipole interference, challenging the belief that they only arise from spin-orbit interactions.

Contribution

It demonstrates that optical localization errors and apparent shifts can occur with spinless beams, highlighting a new interference mechanism involving electric and magnetic dipoles.

Findings

Optical mirages can occur with linearly polarized light.

Interference between electric and magnetic dipoles causes apparent shifts.

Spin-orbit interactions are not the sole origin of optical mirages.

Abstract

Spin-orbit interactions of light are ubiquitous in multiple branches of nanophotonics, including optical wave localization. In that framework, it is widely accepted that circularly polarized beams lead to spin-dependent apparent shifts of dipolar targets commonly referred to as optical mirages. In contrast, these optical mirages vanish when the illumination comes from a spinless beam such as a linearly polarized wave. Here we show that optical localization errors emerge for particles sustaining electric and magnetic dipolar response under the illumination of spinless beams. As an example, we calculate the optical mirage for the scattering by a high refractive index nanosphere under the illumination of a linearly polarized plane wave carrying null spin, orbital, and total angular momentum. Our results point to an overlooked interference between the electric and magnetic dipoles rather than the spin-orbit interactions of light as the origin for the tilted position of the nanosphere.