Multifunctional and broadband cross-shaped metasurfaces for simultaneous polarization conversion and anomalous reflection

By leveraging localized resonance modes and phase-gradient engineering, metasurfaces can effectively control the wavefront of electromagnetic waves. However, most previously reported metasurfaces can only control the anomalous diffraction orders of electromagnetic wave beams. In this work, we design cross-shaped metasurfaces that can simultaneously control polarization conversion and diffraction orders, enabling flexible control of electromagnetic waves. The proposed metasurface consists of periodically arranged cross-shaped metal resonant unit cells, which utilize structural anisotropy to simultaneously modulate co-polarized and cross-polarized waves of circularly polarized incident waves. Both theoretical and experimental results demonstrate that the proposed metasurface can flexibly manipulate the reflected wavefront and achieve free conversion between linear and circular polarization states through the synergistic effects of the resonance phase and geometric phase of the unit cell. Our results show that the proposed metasurface can achieve synergistic optimization of broadband coverage, high efficiency, and multifunctional capabilities, providing a multidimensional, more adaptable, and highly efficient solution for electromagnetic wave manipulation.