Transmissive Electromagnetic Metasurfaces: Physics And Applications

The interaction between light and matter has always been an important focus in physics research.Through in-depth investigations,many important applications in physics have emerged.However,natural materials limit the regulation of electromagnetic waves.For this reason,the concept of electromagnetic metamaterials is proposed in this study.Electromagnetic metamaterials are composed of artificial subwavelength structures.By changing the shape of the structure,electromagnetic metamaterials may attain arbitrary electromagnetic responses.The introduction of electromagnetic metamaterials introduces a novel modality for people to manipulate electromagnetic waves and produced many novel physical phenomena.Moreover,the idea of electromagnetic metasurfaces(two-dimensional electromagnetic metamaterials)has also been put forward thanks to the metasurfaces' simple structure and ease of processing,which quickly enabled them to be popular research topic.This paper focuses on transmissive electromagnetic metasurfaces.The main research contents and results are summarized as follows:1.The interaction between phase coverage as well as the number of layers in a multilayer transmissive electromagnetic metasurface is elucidated.Here,general guidance for the design of a multilayer transmissive electromagnetic metasurface is also provided.Through the analysis of the coupled-mode theory,we find that the phase of an electromagnetic metasurface with a specific structure only covers a specific range.Although increasing the number of electromagnetic metasurface layers enlarges the phase coverage,a better method is to acquire the expected phase coverage through the combination of electromagnetic metasurfaces using different configurations.2.The designs of three different functions of electromagnetic wave control devices are proposed based on the results of theoretical analysis: a quarter-wave plate implemented with a two-layer structure with an opaque background;a half-wave plate implemented with a three-layer structure with an opaque background;and a beam deflector implemented by combining two different configurations of electromagnetic metasurfaces.The results of the simulations and experiments are well aligned with the theoretical predictions.3.The paper introduces a method for implementing electromagnetic transparent windows.This method achieves broadband and efficient electromagnetic transparency via manipulation of the medium's Fabry-Pérot resonance.Only one layer of the metal structure is necessary in its implementation,which is facilitates its design.The corresponding simulation and experimental results demonstrate that this method is very robust to oblique incidence.