Yuancong Cao | Searcharxiv

arXiv2026

Propagation invariant one-dimensional flat-top vector beam with conserved topology

We report the generation and control of a propagation invariant one-dimensional flat-top vector beam through the digitally controlled superposition of a first-order petal- and Gaussian- mode each marked with orthogonal polarizations. We present a detailed analysis of the spatial and polarization profiles and unveil their intricate topological features, showing that they have properties that are invariant to the propagation dynamics, in addition to their preserved intensity. The differential Gouy phase between the spatial components is shown to rotate the great circle traced by the polarisation distribution on the Poincaré sphere. Finally, we assess the beams for laser cutting and optical trapping, highlighting the relevance of topological structured light to these applications.

physics.optics↗

arXiv2026

Fractional optical skyrmions

Optical topologies in the form of Skyrmions have attracted significant interest of late, where their integer Skyrmion number has been shown to be robust to complex media. Here we create the first fractional Skyrmions by structuring light as a vectorial superposition of non-integer orbital angular momentum. We unravel the map structure to reveal a new phenomenon, the abrupt transition jumps in skyrmion number, which serves to reinforce the integer nature of skyrmion topologies. Our experimental demonstration agrees well with simulation, opening a new spectrum of optical topologies to explore, with exciting possibilities in optical communication and sensing.

physics.optics↗