Intrinsic Rashba Spin-Orbit Coupling in Staggered-Gyromagnetic Photonic Crystals

We report the realization of intrinsic Rashba spin-orbit coupling (SOC) in a two-dimensional photonic crystal composed of staggered-gyromagnetic cylinders in a modified honeycomb lattice. The system exhibits a Mexican-hat-like band structure and helical spin textures, which is the major characteristics of Rashba SOC. Through both full-wave simulations and k-p theory, we confirm the emergence of spin-split bands and vortex-like spin textures centered at the Brillouin zone. In addition, under oblique incidence, the Rashba band dispersion gives rise to concurrent negative and a positive refraction. These results establish a platform for exploring intrinsic Rashba photonics and spin-controlled wave transport in periodic systems.