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Metasurfaces, known as arrays of subwavelength antennas, provide a wide range of options for controlling electromagnetic waves and effectively reducing the size and complexity of electromagnetic devices. Metasurfaces can manipulate five degrees of freedom of electromagnetic waves: amplitude, wavelength, polarization, phase, and orbital angular momentum; these are customized to provide a variety of remarkable functionalities, including metalenses and meta-holograms. With the advancement of simultaneously manipulating two or more degrees of freedom of the electromagnetic field, there has been a significant increase in the amount of information that electromagnetic waves can carry. The wavefront can be precisely tailored for specific applications, facilitating new possibilities for innovative applications with high performance and diverse functionalities, such as full-color vectorial meta-holograms achieved by a single-layer metasurface. This review briefly overviews the latest developments in metasurfaces, categorizing them based on their various degrees of freedom used to manipulate the electromagnetic waves. The use of metasurfaces to control electromagnetic waves from one dimension to multiple dimensions is systematically explored. The challenges and opportunities for future research are discussed.
Zhang et al. (Fri,) studied this question.