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Abstract Metasurfaces are ultra‐thin micro‐nano elements, have abundant freedoms, and are widely used in light field transformation. The Jones matrix of single‐layer birefringent metasurfaces have at most 6 degrees of freedom, which limits the richness and diversity of light field transformation. Bilayer metasurfaces have more design channels and functionality than single‐layer metasurfaces. By mathematical derivation, the decomposition method of the bilayer metasurface unitary Jones matrix is provided. Further, inspired by double‐phase holography, arbitrary complex Jones matrix is decomposed and realized by bilayer metasurface and achieves analytical decoupling of all 4 complex components of the Jones matrix. As the theoretical verification, spin‐orbit angular momentum mapping and four‐channel complex holography are realized by the bilayer metasurface. The decomposition method is completely analytical, universal, and easy to implement. It is of great significance for the transformation of light field, information transmission, and optical encryption based on metasurfaces.
Zhang et al. (Sun,) studied this question.