Tailoring propagation-invariant topology of optical skyrmions with dielectric metasurfaces

Optical Stokes skyrmions represent an emerging class of structured light characterized by intricate topological polarization textures in the beam's transverse plane. Traditional methods for generating Stokes skyrmions rely on bulky optical setups, driving significant interests in compact, single-device solutions. However, existing approaches fail to ensure propagation-invariant topology, an imperative requirement for advancing applications in this field. In this paper we address this fundamental challenge with a metasurface design based on structural birefringence and geometric phase which manipulates light in dynamic phase iso-curves, achieving arbitrary co-polarization to cross-polarization conversion while maintaining a constant dynamic phase. This design enables propagation-invariant topological features of optical skyrmions produced by a single generation device. Our framework offers a compact platform for shaping topologically stable optical skyrmions, which may stimulate their applications for long-range optical information transfer.