Electromagnetic metagratings for diffraction fields manipulation

Metagrating, an engineered surface platform that facilitates desired wavefront manipulation through precise control of diffraction orders, has attracted significant attention from researchers in both academia and industry in recent years. This interest is largely due to its exceptional capability to manipulate diffraction fields, achieving nearly 100% efficiency in various extreme and complex wavefront transformations. In metagratings’ design, the first step is to select the periodicity that supports a specific number of propagating diffraction modes. Next, the design of the individual meta-atoms allows for independent control of these diffraction modes, enabling wavefront manipulation. In this paper, we first elucidate the fundamental operating principles of electromagnetic metagratings. We then provide a comprehensive overview of existing research on metagratings across a range of frequencies—from optical and near-infrared to terahertz, millimeter-wave, and microwave—discussing their design methodologies as well as the materials and structures employed. We believe that multifunctional and reconfigurable metagratings will be key trends in the future development of this research field, with promising applications in antennas and radio-frequency devices.