Nature-inspired orbital angular momentum beam generator using aperiodic metasurface

Abstract

This article presents the design of reflective nature-inspired metasurfaces for generation of wideband and high purity circularly polarized (CP) orbital angular momentum (OAM) waves. It has been shown in this article that the breaking of the transitional periodicity and the combination of aperiodic nature-inspired distribution of sub-wavelength sized meta-atoms based on Pancharatnam–Berry (PB) phase theory can lead to OAM beams of high purity with improved bandwidth. The distribution of the PB anisotropic meta-atoms across the proposed metasurface aperture is non-uniform and distributed along logarithmic spirals similar to sunflower seeds, i.e. outwardly logarithmic spiral lattices of no transitional periodicity. The proposed reflective CP-OAM beam generator metasurface diameter is 140 mm, thickness ≈ 0.11λ 17GHz and has 600 anisotropic spatially rotated PB meta-atoms of sub-wavelength size of 5 mm ≈ 0.28λ 17GHz. Four OAM metasurface generators have been designed to produce OAM waves of various modes from 1 to 4. Both simulation and experimental results have demonstrated that the proposed metasurfaces can efficiently generate CP-OAM beams from 13.1 GHz to 20.5 GHz (BW = 44%) with high mode purity >90%.

Transmissive Digital Coding Metasurfaces for Polarization-Dependent Dual-Mode Quad Orbital Angular Momentum Beams

“…For comparison, the existing methods from previous studies and the proposed design are presented in Table . − ,,− Multiple feeding source systems can expand the coding channel to realize the function of multiplexing, but it is limited to the complex structures. On the contrary, only a single linearly polarized horn antenna was utilized to feed the TDC-MS in this work.…”

“…Since then, a reflective nature-inspired metasurface was illuminated to generate high-purity OAM based on sunflower-like Pancharatnam−Berry (PB) elements with circularly polarized incidence. 32 Generally, the multimode and multibeam OAM that can further promote communication capability by mode-division multiplexing and space-division multiplexing has greater significance in the wireless systems. For instance, a digital coding metasurface was presented based on the convolution theorem for achieving multiple functions in the reflective mode.…”

“…This method gives a new way to generate OAM beams. Since then, a reflective nature-inspired metasurface was illuminated to generate high-purity OAM based on sunflower-like Pancharatnam–Berry (PB) elements with circularly polarized incidence . Generally, the multimode and multibeam OAM that can further promote communication capability by mode-division multiplexing and space-division multiplexing has greater significance in the wireless systems.…”

SUTD-PRCM Dataset and Neural Architecture Search Approach for Complex Metasurface Design

“…Due to the interaction between an electromagnetic (EM) wave and metasurfaces in some specific geometrical arrangements, metasurfaces can exhibit remarkable electromagnetic wave responses that have attracted great interests [1][2][3][4]. Metasurfaces have served as an important technology in many applications such as heat transforming [5], cloaking [6,7], hologram [8], conversion [9], absorption [10,11], scattering reduction [12], polarization [13][14][15], transmission [16], color [17,18], metalense [14,15], programmable metasurfaces [19][20][21], and many others [22][23][24][25]. These applications are made possible by the rapid advancement in micro-and even nano-fabrication technologies and computational modeling over the past decades.…”

Symmetry Enhanced Network Architecture Search for Complex Metasurface Design

“…Due to the electromagnetic (EM) wave or light-matter interaction, specified designed metasurfaces in some unique patterns can exhibit remarkable EM responses or light outputs for many applications [1]- [15]. Some examples are heat transforming [16], cloaking [17], [18], hologram [19], conversion [20], absorption [21], [22], scattering [23], polarization [24]- [26], transmission [27], different colors [28], [29], meta-lense [25], [26], programmable metasurfaces [30]- [32], and many others [33]- [36]. These applications are made possible by the rapid advancement in micro-and even nanofabrication technologies and computational modeling over the past decades.…”