Polarization-insensitive, Broadband, and High-Efficiency Metasurface for Holographic Imaging

In this paper, a systematic design strategy of polarization-insensitive, broadband, and high-efficiency metasurface is reported, and the proposed metasurface has excellent performance in holographic imaging. First, we utilize a multi-objective differential evolution algorithm to rapidly design a high-performance meta-atom group, capable of achieving a reflected amplitude (efficiency) exceeding 0.91 (83%) within the bandwidth of 8.21-17.50 GHz. Subsequently, a wideband phase distribution method is proposed for calculating the imaging phase map. Guided by the phase map, the meta-array is designed for the generation of letter-shaped images under distinct polarization excitation across the entire bandwidth. Finally, calculations, simulations, and experiments collectively verify the effectiveness of the systematic design strategy utilized in holographic imaging. The metasurface sample has the capability to generate letter-shaped images at varying heights with an imaging efficiency over 62.8%. The proposed method can be employed to achieve the unrestricted distribution of electromagnetic wave energy in three-dimensional space, encompassing applications such as wireless charging, data storage, and microwave imaging.