Absorption and polarization based on metastructures: a review

Metastructures (MSs) are artificial electromagnetic materials with specific design sizes, and their structure is composed of periodic or aperiodic arrangements of basic elements. These new electromagnetic materials exhibit some unique electromagnetic properties and phenomena compared with natural materials and can achieve richer and more personalized functions. Various phenomena based on MSs have attracted the interest of many researchers, among which absorption and polarization phenomena have attracted much attention due to their unique functions and properties. Different from ordinary absorbers and polarization converters (PCs), devices that are studied and designed using the absorption and polarization properties of MSs have often demonstrated better performance and unique functions and are widely used in different fields and disciplines, such as military, communications and medicine, with extensive potential. In the early days, absorbers and PCs had various problems, such as single frequency performance, poor controllability, angle sensitivity, and narrow bandwidth, and the introduction of MSs has improved and solved these problems. This article reviews the development of MS-based absorbers and PCs and describes their reconfigurable techniques, performance optimization techniques, and potential applications. In addition, it analyzes and discusses the latest research on absorption and polarization phenomena based on MSs and put forward the possible future research directions and prospects.