“…Metasurfaces are the two-dimensional equivalent of metamaterials, possessing the remarkable ability to flexibly manipulate the amplitude, phase, and polarization of electromagnetic waves by periodically arranging subwavelength structures, which opens a new era of digital optics. − Many exotic phenomena and applications have been observed with metasurfaces, such as the compact spectrometer, , optical computing, , optical biosensing, , quantum entanglement, , asymmetric photonic spin–orbit interactions, − achromatic and ultrawide-angle lenses, − and simultaneous circular dichroism and wavefront manipulation. − Various structures, such as the quasi-split-ring resonator, helical surface arrays, and chiral stepped nanoaperture, have been proposed. However, these methods increase the complexity of design and fabrication due to the requirement of structures to break the n -fold ( n > 2) rotational and mirror symmetries or vertical symmetry.…”