Deep-subwavelength features of photonic skyrmions in a confined electromagnetic field with orbital angular momentum

TL;DR

This paper demonstrates that photonic skyrmions with deep-subwavelength spin structures can be generated in focused vector beams, enabling applications in high-resolution imaging, metrology, and quantum technologies by exploiting spin rather than intensity.

Contribution

It introduces the concept of photonic skyrmions with subwavelength spin structures resulting from spin-orbit coupling in focused vector beams, surpassing diffraction limits on spin pattern size.

Findings

Photonic skyrmions exhibit spin structures down to 1/60 of light wavelength.

The spin distribution can be confined to approximately 10 nanometres.

Deep-subwavelength spin patterns are achievable despite diffraction limits on intensity.

Abstract

In magnetic materials, skyrmions are nanoscale regions where the orientation of electron spin changes in a vortex-type manner. Here we show that spin-orbit coupling in a focused vector beam results in a skyrmion-like photonic spin distribution of the excited waveguided fields. While diffraction limits the spatial size of intensity distributions, the direction of the field, defining photonic spin, is not subject to this limitation. We demonstrate that the skyrmion spin structure varies on the deep-subwavelength scales down to 1/60 of light wavelength, which corresponds to about 10 nanometre lengthscale. The application of photonic skyrmions may range from high-resolution imaging and precision metrology to quantum technologies and data storage where the spin structure of the field, not its intensity, can be applied to achieve deep-subwavelength optical patterns.