Phase-engineered metalenses to generate converging and non-diffractive vortex beam carrying orbital angular momentum in microwave region

Abstract

In this paper, ultra-thin metalenses are proposed to generate converging and non-diffractive vortex beam carrying orbital angular momentum (OAM) in microwave region. Phase changes are introduced to the transmission cross-polarized wave by tailoring spatial orientation of Pancharatnam-Berry phase unit cell. Based on the superposition of phase profile of spiral phase plate and that of a converging lens or an axicon, vortex beam carrying OAM mode generated by the metalens can also exhibit characteristics of a focusing beam or a Bessel beam. Measured field intensities and phase distributions at microwave frequencies verify the theoretical design procedure. The proposed method provides an efficient approach to control the radius of vortex beam carrying OAM mode in microwave wireless applications for medium-short range distance.

High‐Efficiency Ultrathin Dual‐Wavelength Pancharatnam–Berry Metasurfaces with Complete Independent Phase Control

“…2019, 7,1900594 respectively, which could be calculated by decomposing its com plex field on a complete basis set of Laguerre-Gaussian modes (E l p , LG ). [19] The proposed dualwavelength vortex beam generator is also verified through experimental measurements. Some phase noise at other modes for λ 2 might be due to the larger topological charge and digitization loss.…”

“…Typically, metasurfaces are constructed of metal [5,6] or dielectric [7,8] metaatoms with delicately designed geometries and orientations to locally modulate the pro perties of the scattered EM wave. [16][17][18][19] In addition, the concept of meta surface has also been adopted in many other research areas, such as the elastic meta surfaces [20,21] and acoustic metasurfaces. [16][17][18][19] In addition, the concept of meta surface has also been adopted in many other research areas, such as the elastic meta surfaces [20,21] and acoustic metasurfaces.…”

“…Due to the unpre cedented abilities to manipulate the EM wavefronts, metasurfaces have attracted enormous interests in different parts of the frequency spectra, and enabled a lot of novel planar metadevices, such as ultrathin skin cloak, [9] metaholograms, [10] polarization con verters, [11] spin Hall effects, [12,13] metalenses, [14,15] and vortex beam generators. [16][17][18][19] In addition, the concept of meta surface has also been adopted in many other research areas, such as the elastic meta surfaces [20,21] and acoustic metasurfaces. [22,23] Although metasurfaces have been widely studied since their emergence, most metasurface devices are designed to operate at a single wavelength, and their function alters or the performance deteriorates as the wavelength is varied due to the dispersion nature.…”

Realizing Broadband Transparency via Manipulating the Hybrid Coupling Modes in Metasurfaces for High‐Efficiency Metalens

“…Own to the powerful wave manipulation abilities and planar characteristics, metasurface possesses special advantages compared with traditional optical devices, such as low profile, easy fabrication, and integration. In recent years, singular electromagnetic properties have been realized by metasurface, including anomalous reflection/refraction, flat lens, plasmonic lithography, high‐resolution imaging, vortex beam generation, and computer‐generated holograms . Among these, the metalenses are the indispensable elements in the design of the functional optical devices .…”

Metasurface cavity antenna for broadband high‐gain circularly polarized radiation

“…After the introduction of generalized laws of optics by Yu et al, investigations in metasurfaces (2D counterparts of metamaterials) gave the wave‐material interaction a paradigm shift. In the beginning, devices like optical holograms, ultrathin lens, EM cloaks, vortex generators, etc, are designed by printing sub‐wavelength scatters over thin substrates. Latter, miniaturized high‐gain reflectarray, transmitarray, and hybrid antennas are reported using phase engineering based metasurface.…”