In this Letter, we report the significant enhancement of the photonic spin Hall effect (SHE) in a plasmonic metasurface with ${\rm S}_4$ symmetry. We find that an enhanced SHE of reflected light can occur in both horizontally and vertically polarized incident beams, and the maximum transverse displacement can approach half of the beam waist. Such a large displacement is caused by the non-resonant and near-zero pseudo-Brewster angles in the plasmonic metasurface. Owing to ${\rm S}_4$ symmetry, a unidirectional SHE is obtained in the metasurface, i.e., large and tiny transverse displacements are realized for a linearly polarized beam incident from the opposite side. This Letter provides a new, to the best of our knowledge, way to achieve an enhanced photonic SHE and offers more opportunities for designing spin-based nanophotonic devices.

中文翻译：

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具有S ₄对称性的等离子体超表面中的增强单向光子自旋霍尔效应

在这封信中，我们报告了具有$ {\ rm S} _4 $对称性的等离子后表面中光子自旋霍尔效应（SHE）的显着增强。我们发现，在水平和垂直偏振入射光束中都会出现反射光增强的SHE，并且最大横向位移可以接近光束腰的一半。如此大的位移是由等离子超颖表面中的非共振角和接近零的伪布鲁斯特角引起的。由于$ {\ rm S} _4 $对称地，在超表面上获得了单向SHE，即，对于从相反侧入射的线偏振光束，实现了大而微小的横向位移。据我们所知，这封信提供了一种新的方法来实现增强的光子SHE，并为设计基于自旋的纳米光子器件提供了更多机会。