Topological Quasiparticles of Light: From Spin‐Orbit Coupling to Photonic Skyrmions
Xinrui Lei, Qiwen Zhan
Abstract
Abstract Topological quasiparticles characterized by nontrivial spin textures such as skyrmions and merons have been demonstrated across various physical systems, including Bose–Einstein condensates, nematic liquid crystals, and chiral magnets. Their photonic counterparts are observed recently with the topological structures formed through the precise manipulation of electromagnetic fields across synthetic dimensions, which provides a novel degree of freedom to manipulate light–matter interactions and promises advanced applications. While photonic skyrmions have been realized in diverse vectorial electromagnetic fields, the intrinsic spin‐orbit coupling (SOC) of light plays a pivotal role, as it engenders spin‐dependent spatial dynamics of the optical field and gives rise to the characteristic topological winding of engineered vector beams. In this review, the recent development of photonic skyrmions with a focus on SOC‐enabled structured light is outlined. Starting from the fundamental mechanisms governing SOC in tailored optical fields, how spatially inhomogeneous polarization and phase give rise to nontrivial topological features is elucidated. Further, the topology of photonic skyrmions under various SOC manipulations is discussed, and cutting‐edge applications are addressed. Through highlighting the interplay between SOC and topological field configurations, this review provides perspectives on harnessing topological quasiparticles of light in next‐generation photonic technologies.