Phase and Polarization Modulations Using Radiation‐Type Metasurfaces

Abstract

Metasurfaces exhibit promising capacities in the manipulation of electromagnetic (EM) waves, as to diverse dimensions like amplitude, phase, and polarization; even multiple dimensions can be synchronously modulated. Despite the rapid progress in enriching regulatory capabilities of EM waves, primary feeds are integral items however bringing profile elevation, energy obstruction, and leakage, both for reflection‐type and transmission‐type metasurfaces. Aiming at maintaining high operating efficiency and in meantime implementing multiple dimensional manipulations of EM waves, the authors present a concise design of radiation‐type metasurfaces, whose distinctive feature stands that each meta‐atom serves not only as geometry phase provider, but as radiator itself so as to spare primary feeds. To further achieve full phase modulation for arbitrary linear polarized radiations and abate innate conjugacy to orthogonal circular polarized radiations, the propagation phase is introduced irrelevant to geometry ones. Based on the radiation‐type metasurface with 0.07‐wavelength low profile, the authors verify experimentally advanced radiation functions for different polarizations like orbital angular momentum beams, asymmetric beams, and time‐reversed focusing. Compared with traditional planar arrays that rely on feeding networks to realize phase modulation, this design provides the possibility to achieve direct phase and polarization modulation at the element level, thus is with less complexity.

Radiation‐Type Programmable Metasurface for Direct Manipulation of Electromagnetic Emission

“…To overcome this issue, many mentalities of designing are introduced to narrow the feeding path length, for example, folded-reflectarray metasurface, [29] folded-transmitarray metasurface, [30] Fabry-Perot type metasurface, [31] and ultimately, radiation-type metasurfaces integrated with direct microwave feed. [32][33][34] Nevertheless, only fixed shaped beams can be stimulated through using these passive methods, that is, the metasurfaces are not reconfigurable and the beams generated cannot be modulated in a single metasurface. Similar designs with digital programmable metasurfaces have been rarely reported to the best of our knowledge, until recently, programmable folded-reflectarray metasurfaces based on PIN diodes were developed for wide-angle beam scanning applications or multifunctional OAM generation, [35,36] which suffer from very low aperture efficiencies along with high sidelobe levels.…”

Metasurface‐Assisted Indirect‐Observation Cryptographic System

“…With the rapid development of technology, information security has become a more and more urgent demand, and many efforts have been made to prevent information leakage. Among them, optical encryption metasurface has been demonstrated as an effective recipe due to its incomparable ability of light manipulation for optical properties like polarization, [1][2][3][4][5][6] amplitude, [7][8][9][10] and phase. [11][12][13][14][15][16][17][18][19][20][21] Recent studies have showcased that metasurface can hide a highresolution image into polarization distribution of light [1,2] based on Malus' law.…”

Single-sized metasurface for simultaneous pseudo-color nanoprinting and holographic image display

“…Benefiting from the incomparable capability of manipulation for optical properties such as phase (Hao et al, 2021;Wang et al, 2021;Zhang H. et al, 2022;Cheng et al, 2022;Ma et al, 2022;Ming et al, 2022;Tao et al, 2022), polarization (Ouyang et al, 2021;Xu et al, 2021;Deng J. et al, 2022;Zhang S. et al, 2022;Kim et al, 2022; and amplitude Ren et al, 2021;Zheng et al, 2021;Deng L. et al, 2022;Yang et al, 2022), metasurface has emerged as a powerful platform for implementing multifunctional devices Chen et al, 2020;Dai et al, 2020;Li et al, 2020;Li J. et al, 2021). By dividing the metasurface into different parts, the segmenting metasurfaces have showcased their ability to integrate different functions, e.g., imaging and nanoprinting (Chen et al, 2020) or near-and far-field display together (Dai et al, 2020).…”