Multifunctional Metasurfaces Based on the “Merging” Concept and Anisotropic Single-Structure Meta-Atoms

Abstract

Metasurfaces offer great opportunities to control electromagnetic (EM) waves, attracting intensive attention in science and engineering communities. Recently, many efforts were devoted to multifunctional metasurfaces integrating different functionalities into single flat devices. In this article, we present a concise review on the development of multifunctional metasurfaces, focusing on the design strategies proposed and functional devices realized. We first briefly review the early efforts on designing such systems, which simply combine multiple meta-structures with distinct functionalities to form multifunctional devices. To overcome the low-efficiency and functionality cross-talking issues, a new strategy was proposed, in which the meta-atoms are carefully designed single structures exhibiting polarization-controlled transmission/reflection amplitude/phase responses. Based on this new scheme, various types of multifunctional devices were realized in different frequency domains, which exhibit diversified functionalities (e.g., focusing, deflection, surface wave conversion, multi-beam emissions, etc.), for both pure-reflection and pure-transmission geometries or even in the full EM space. We conclude this review by presenting our perspectives on this fast-developing new sub-field, hoping to stimulate new research outputs that are useful in future applications.

Gap-surface plasmon metasurfaces for linear-polarization conversion, focusing, and beam splitting

“…In addition to the specific functionalities, strongly anisotropic GSP meta-atoms have been utilized to achieve linear-polarization-selective [23][24][25] or spin-selective [25,26] distinct functionalities, where each polarization state is subjected to a different wavefront transformation. However, the aforementioned linear-polarization-selective GSPMs lack the capability of polarization conversion, which is detrimental for the signal-to-noise ratio due to the overlap between the signal beam and the background.…”

Electromagnetic metasurfaces: physics and applications

“…Facing increasing demands on the speed and memory of EM devices, EM integration is highly desired in modern science and technology. Metasurfaces are ideal candidates to integrate multiple diversified functionalities into single devices with deep-subwavelength thickness and high efficiencies [349]. Various approaches have recently been proposed to achieve this goal, which will be briefly summarized in this subsection.…”

Dual-Band Metasurfaces Using Multiple Gap-Surface Plasmon Resonances

“…With the freedom to arbitrarily control the phase, amplitude, and polarization of reflected light at the subwavelength scale, gap-surface plasmon (GSP) metasurfaces allow one to engineer selective properties of meta-atoms and integrate multiple functionalities in a single device with excellent performance. − This property has shown immense potential for versatile applications that cannot be implemented using bulk optical devices, relying on the phase accumulation when propagating through a high-refractive index medium between polished surfaces. However, the applicability of metasurfaces for multiwavelength operations is typically restricted because of the dispersion-limited response of meta-atoms.…”