Topological Spin‐Momentum Flows on a Silicon Chip

The emerging topological structures within electromagnetic fields have attracted great interest because of their unique properties and potential applications. Here, we introduce interesting electromagnetic spin‐momentum topologies on silicon‐based waveguides, characterized by spin skyrmion (meron‐antimeron) arrays overlapped with momentum vortices yielding local transverse orbital angular momentum. These composite textures, derived from Poynting vortex streets, are produced by vectorial superpositions of two counter‐propagating modes with different orders. Importantly, these topological structures can be dynamically controlled to transverse shift and longitudinal flow by modulating the relative amplitudes and phases (or frequencies) between the counter‐propagating modes, respectively. The controllable topological spin‐momentum flows uncovered here may open new doors to on‐chip optical manipulation, sorting, waveguide quantum electrodynamics, and optofluidic techniques.