High-performance and ultra-broadband vortex beam generation using a Pancharatnam–Berry metasurface with an H-shaped resonator

Abstract

Vortex beams carrying orbital angular momentum (OAM) are expected to efficiently increase channel capacity in communication sectors, so ultra-broadband vortex beam generators with high performance are important in next-generation communication systems. Based on the concept of the Pancharatnam–Berry phase, we propose a metasurface with an H-shaped resonator for realizing vortex beam generation within an ultra-wideband frequency range from 7.3 to 21 GHz (relative bandwidth = 96.8%). The designed meta-atom can acquire high efficiency (efficiency ≥ 92%) conversion from the incident plane wave to the reflected vortex wave across the entire frequency band. To verify the performance of the proposed metasurface, a reflective array consisting of 18 × 18 single-layered elements with different rotated angles is simulated for generating the vortex beam with a topological charge of ±2. Through OAM spectral analysis, the left-handed components of the reflected electric fields and mode purity of the generated vortex beams under different frequencies are achieved and discussed in detail. Then the metasurface is fabricated and measured, and the numerical and experimental results coincide well, proving the effectiveness and high performance of the proposed design.

Spin‐Selective Absorption and Geometric‐Phase Modulation via Chiral Metasurface in Triple Bands

“…Metasurfaces, the 2D equivalence of metamaterials, have been extensively investigated and employed to flexibly manipulate the electromagnetic properties of reflected/refracted waves. [1,2] Thanks to the abrupt phase change of the metasurface within sub-wavelength scale, many fascinating physical phenomena and promising applications have been proposed one after another, for instance, anomalous reflection/refraction, [3] polarization conversion and absorption, [4,5] beam focusing, [6,7] vortex beams, [8][9][10] and hologram imaging. [11,12] Nevertheless, with the rapid development of modern wireless technologies, single-functional metasurfaces gradually fail to meet practical needs.…”

Design of liquid crystal metalens for achromatic full-color imaging with multiplexed phase coding

“…Various functions based on compact and efficient metasurface have been proposed and demonstrated, such as holograms 7 , metalens 8, 9, and vector beam generators 10,11 . Metasurface based on Pancharatnam-Berry (PB) phase have garnered significant attention due to its remarkable capability of polarization dependent phase manipulation and high diffraction efficiency [12][13][14][15] . These PB phase based elements are flat with a patterned orientation of the anisotropy axis of each meta-atom, resulting in a polarization-dependent response upon incident circularly polarized light.However, conventional metasurface based on either dielectric or metallic meta-atoms also faces several challenges in practical applications, such as the complexity of fabrication and the lack of dynamic adaptability.…”

Light-controlled metasurface with a controllable range of reflection phase modulation

“…By elaborating the element structure and manipulating the array wavefront of MS, we can achieve wireless power transfer [1][2][3], reduce the radar cross-section [4][5][6], or arbitrarily control the characterized properties of reflected and transmitted EM waves, including propagation direction [7], amplitude, phase, polarization * Authors to whom any correspondence should be addressed. [8,9], and orbital angular momentum (OAM) mode [10][11][12][13]. Furthermore, the reconfigurable MS has tunable EM scattering characteristics controlled by external direct-current (DC) bias [14][15][16][17][18][19][20][21][22][23][24][25], light [26][27][28][29][30][31][32][33][34], temperature [35,36], and other factors, which is extremely valuable in innovative communication applications [19,21,24].…”