Spontaneous optical skyrmion generation by frequency doubling in underdense plasmas

TL;DR

This paper demonstrates spontaneous generation of optical skyrmions in underdense plasmas via frequency doubling, linking plasma inhomogeneities to skyrmion deformation and enabling plasma density diagnostics.

Contribution

It reveals a new mechanism for skyrmion formation through second-order harmonic generation in plasmas without complex wave engineering.

Findings

Skyrmions emerge spontaneously in frequency-doubled plasma fields.

Electron density gradients deform skyrmionic textures.

Skyrmion structures can diagnose plasma density variations.

Abstract

Optical skyrmions have been widely explored in recent years. Among them, Stokes skyrmions require sophisticated wave engineering or photonic devices for their generation. We show that Stokes skyrmions can emerge spontaneously in second-order harmonic generation in underdense plasmas driven by optical vortices. The nonlinear response produces a structured frequency-doubled field whose polarization texture maps the Poincar\'e sphere. When plasma inhomogeneities are taken into account, the electron density gradient deforms the skyrmionic texture, enabling topological diagnosis of plasma density.