Metasurface-based wide-angle reflective metalens with consistently constant focusing efficiency

Terahertz (THz) communication technology has drawn a lot of attention due to advancements in global research and aspirations for 6G communication as well as the development of THz technology. It is desirable to have a reflective metalens that can gather light from many directions and focus it at a fixed place. We employed the diffractive neural network (DNN) to design a wide-angle metasurface-based reflective metalens in order to meet this technical need. This reflective metalens is capable of consistently and efficiently reflecting incident light from a wide angle of incidence and focusing it into one spot. The DNN is used to quantitatively optimize the phase distribution of the reflective metalens and the resonance phase modulation approach is adopted to develop the unit structure. Both simulation and experimentation in a 220 GHz environment were used to confirm the reflective metalens's functionality. Through increased wide-angle reflection and directional focusing homogeneity and efficiency, the suggested technology offers a practical means of addressing the problems associated with 6G communication.