Electromagnetic wave manipulation based on few-layer metasurfaces and polyatomic metasurfaces

Metasurfaces,whose electromagnetic(EM)responses can be artificially designed,are two-dimensional arrays composed of subwavelength nanostructures.Accompanied by various fascinating developments in the past decade,metasurfaces have been proved as a powerful platform for the implementation of EM wave manipula-tion.However,the planar monoatomic metasurfaces widely used in previous works have limited design freedoms,resulting in some disadvantages for the realization of high-performance and new functional EM wave control.The latest developments show that few-layer metasurfaces and polyatomic metasurfaces are good alternatives to overcome the drawbacks of planar monoatomic metasurfaces and realize high-efficient,multi-band and broad-band EM functionalities.They provide additional degrees of design freedom via introducing multilayer layouts or combining multiple meta-atoms into a unit cell respectively.Here,recent advances of few-layer and polyatomic metasurfaces are reviewed.The design strategies,EM properties and main advantages of few-layer metasurfaces and polyatomic metasurfaces are overviewed firstly.Then,few-layer metasurfaces and polyatomic metasurfaces in recent progress for EM wave manipulation are classified and discussed from the viewpoint of their design strategy.At last,an outlook on future development trends and potential applications in these fast-developing research areas is presented.