scholarly journals Single-layer phase gradient mmWave metasurface for incident angle independent focusing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wonwoo Lee ◽  
Semin Jo ◽  
Kanghyeok Lee ◽  
Hong Soo Park ◽  
Junhyuk Yang ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
Phase Distribution ◽  
Focal Point ◽  
Incident Angle ◽  
Rapid Development ◽  
Single Layer ◽  
Phase Gradient ◽  
Wave Focusing ◽  
Practical Applications

AbstractMetasurfaces allow the rapid development of compact and flat electromagnetic devices owing to their capability in manipulating the wavefront of electromagnetic waves. Particularly, with respect to the metasurface lenses, wide operational bandwidth and wide incident angle behavior are critically required for practical applications. Herein, a single-layer phase gradient metasurface lens is presented to achieve millimeter-wave focusing at a focal point of 13 mm regardless of the incident angle. The proposed metasurface lens is fabricated by constructing subwavelength-thick (< λ/10) phase elements composed of two metallic layers separated by a single dielectric substrate that exhibits low-Q resonance properties and a wide phase modulation range with satisfactory transmissivity. By controlling the spatial phase distribution, the proposed metasurface lens successfully realises effective wavefront manipulation properties and high-performance electromagnetic-wave-focusing characteristics over a wide operating frequency range from 35 to 40 GHz with incident angle independency up to 30°.

scholarly journals A Small-Divergence-Angle Orbital Angular Momentum Metasurface Antenna

Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Jianchun Xu ◽  
Ke Bi ◽  
Ru Zhang ◽  
Yanan Hao ◽  
Chuwen Lan ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Electromagnetic Waves ◽  
Divergence Angle ◽  
Compact Structure ◽  
Phase Gradient ◽  
Practical Applications ◽  
Circular Arrangement ◽  
Low Efficiency ◽  
Theoretical Analyses

Electromagnetic waves carrying an orbital angular momentum (OAM) are of great interest. However, most OAM antennas present disadvantages such as a complicated structure, low efficiency, and large divergence angle, which prevents their practical applications. So far, there are few papers and research focuses on the problem of the divergence angle. Herein, a metasurface antenna is proposed to obtain the OAM beams with a small divergence angle. The circular arrangement and phase gradient were used to simplify the structure of the metasurface and obtain the small divergence angle, respectively. The proposed metasurface antenna presents a high transmission coefficient and effectively decreases the divergence angle of the OAM beam. All the theoretical analyses and derivation calculations were validated by both simulations and experiments. This compact structure paves the way to generate OAM beams with a small divergence angle.

scholarly journals Bidirectional Angle-Tolerant Polarization-Tuned Filtering and Wide-Range Refractive Index Sensing Based on Metal Film Coated Nanograting

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Wenli Cui ◽  
Qiannan Wu ◽  
Bo Chen ◽  
Xufeng Li ◽  
Xiaolin Luo ◽  
...  
Keyword(s):  
Refractive Index ◽  
Metal Film ◽  
High Performance ◽  
Incident Angle ◽  
Single Layer ◽  
Transverse Magnetic ◽  
Photonic Devices ◽  
Biomedical Sensors ◽  
Dual Channel ◽  
Wide Range

The miniaturization and integration of photonic devices are new requirements in the fast-growing optics field. In this paper, we focus on a feature-rich sub-wavelength nanograting-coated single-layer metal film. The numerical results show that the reflection behaviors of this proposed structure can realize bidirectional dual-channel ultra-narrowband polarized filtering and bidirectional wavelength-modulated sensing in a wide refractive index (RI) range from 1.0 to 1.4 for incident angle of 10° with transverse-magnetic (TM) polarized illumination at wavelengths between 550 nm to 1500 nm. Moreover, the bidirectional properties of filtering and sensing are not obviously decreased when increasing incident angle from 10° to 30°, and decreasing incident angle from 10° to 0°. The calculated RI sensitivity can be up to 592 nm/RIU with a high figure of merit (FOM) of 179.4 RIU−1. More to the point, this nanograting has a simple structure and is less sensitive to the height and shape of grating ridge, which provides great convenience for the fabrication of devices. The other thing that is going on is that this structure can also realize synchronously tunable color filtering, including green to red, with high color purity in the visible band by choosing the period. The underlying physical mechanism is analyzed in detail, and is primarily attributed to surface plasmon polariton (SPP) resonance and dipole resonance at double plasmon resonance wavelengths. This work has tremendous potential in developing multipurpose and high-performance integrated optical devices such as spectral filters, colored displays and plasmon biomedical sensors.

Optimization and Inverse-design Techniques for Metalens Synthesis

2021 ◽  
Vol 35 (11) ◽  
pp. 1334-1335
Author(s):  
Sawyer Campbell ◽  
Eric Whiting ◽  
Ronald Jenkins ◽  
Pingjuan Werner ◽  
Douglas Werner
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
Inverse Design ◽  
Optical Systems ◽  
Challenging Problem ◽  
Phase Gradient ◽  
Unit Cells ◽  
Cell Components ◽  
Meta Atom ◽  
Design Techniques

Phase-gradient metasurfaces enable designers to tailor the behavior of electromagnetic waves at surfaces by exploiting the generalized form of Snell’s law. This ability has led to the investigation of metalenses which have the potential to significantly reduce the size, weight, and power (SWaP) of conventional optical systems. While traditional lenses are made from individual glasses, metalenses are comprised of patterned meta-atom unit Cells which are arranged in such a way so as to give the metalens its desired behavior. Therefore, any metalens’s performance is ultimately determined by that of its underlying unit cell components. However, designing meta-atoms that simultaneously achieve high performance over wide frequency bandwidths and fields-of-view is an extremely challenging problem that is best addressed with powerful optimization and inverse-design techniques.

scholarly journals A High-Performance Transmitarray Antenna with Thin Metasurface for 5G Communication Based on PSO (Particle Swarm Optimization)

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4460
Author(s):  
Chengtian Song ◽  
Lizhi Pan ◽  
Yonghui Jiao ◽  
Jianguang Jia
Keyword(s):  
Particle Swarm Optimization ◽  
High Performance ◽  
Phase Distribution ◽  
Focal Point ◽  
Low Cost ◽  
Spherical Wave ◽  
Particle Swarm ◽  
Side Lobe Level ◽  
Swarm Optimization ◽  
5G Communication

A 5G metasurface (MS) transmitarray (TA) feed by compact-antenna array with the performance of high gain and side-lobe level (SLL) reduction is presented. The proposed MS has two identical metallic layers etched on both sides of the dielectric substrate and four fixed vias connecting two metallic layers that works at 28 GHz to increase the transmission phase shift range. The proposed planar TA consisting of unit cells with different dimensional information can simulate the function as an optical lens according to the Fermat’s principle, so the quasi-spherical wave emitted by the compact Potter horn antenna at the virtual focal point will transform to the quasi-plane wave by the phase-adjustments. Then, the particle swarm optimization (PSO) is introduced to optimize the phase distribution on the TA to decrease the SLL further. It is found that the optimized TA could achieve 27 dB gain at 28 GHz, 11.8% 3 dB gain bandwidth, −30 dB SLL, and aperture efficiency of 23% at the operating bandwidth of 27.5–29.5 GHz, which performs better than the nonoptimized one. The advanced particularities of this optimized TA including low cost, low profile, and easy to configure make it great potential in paving the way to 5G communication and radar system.

scholarly journals Selection rules of triboelectric materials for direct-current triboelectric nanogenerator

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhihao Zhao ◽  
Linglin Zhou ◽  
Shaoxin Li ◽  
Di Liu ◽  
Yanhong Li ◽  
...  
Keyword(s):  
Charge Density ◽  
Direct Current ◽  
High Performance ◽  
Rapid Development ◽  
Utilization Rate ◽  
Triboelectric Nanogenerator ◽  
Distributed Energy ◽  
Selection Rules ◽  
Practical Applications ◽  
Basic Parameters

AbstractThe rapid development of Internet of Things and artificial intelligence brings increasing attention on the harvesting of distributed energy by using triboelectric nanogenerator (TENG), especially the direct current TENG (DC-TENG). It is essential to select appropriate triboelectric materials for obtaining a high performance TENG. In this work, we provide a set of rules for selecting the triboelectric materials for DC-TENG based on several basic parameters, including surface charge density, friction coefficient, polarization, utilization rate of charges, and stability. On the basis of the selection rules, polyvinyl chloride, used widely in industry rather than in TENG, is selected as the triboelectric layer. Its effective charge density can reach up to ~8.80 mC m−2 in a microstructure-designed DC-TENG, which is a new record for all kinds of TENGs. This work can offer a basic guideline for the triboelectric materials selection and promote the practical applications of DC-TENG.

scholarly journals Mid-infrared polarization-controlled broadband achromatic metadevice

2020 ◽  
Vol 6 (37) ◽  
pp. eabc0711 ◽  
Author(s):  
Kai Ou ◽  
Feilong Yu ◽  
Guanhai Li ◽  
Wenjuan Wang ◽  
Andrey E. Miroshnichenko ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
State Of The Art ◽  
Extinction Ratio ◽  
Chromatic Aberration ◽  
Cmos Technology ◽  
Practical Applications ◽  
Polarization Control ◽  
Large Size ◽  
Polarization Multiplexing

Metasurfaces provide a compact, flexible, and efficient platform to manipulate the electromagnetic waves. However, chromatic aberration imposes severe restrictions on their applications in broadband polarization control. Here, we propose a broadband achromatic methodology to implement polarization-controlled multifunctional metadevices in mid-wavelength infrared with birefringent meta-atoms. We demonstrate the generation of polarization-controlled and achromatically on-axis focused optical vortex beams with diffraction-limited focal spots and switchable topological charge (L∥ = 0 and L⊥ = 2). Besides, we further implement broadband achromatic polarization beamsplitter with high polarization isolation (extinction ratio up to 21). The adoption of all-silicon configuration not only facilitates the integration with CMOS technology but also endows the polarization multiplexing meta-atoms with broad phase dispersion coverage, ensuring the large size and high performance of the metadevices. Compared with the state-of-the-art chromatic aberration-restricted polarization-controlled metadevices, our work represents a substantial advance and a step toward practical applications.

scholarly journals Gallium Nitride Metalens for Image Decryption

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1320
Author(s):  
Meng-Hsin Chen ◽  
Jia-Ying Li ◽  
Vin-Cent Su
Keyword(s):  
Gallium Nitride ◽  
Electromagnetic Waves ◽  
High Performance ◽  
Dielectric Material ◽  
Rapid Development ◽  
Incident Light ◽  
Superposition Principle ◽  
Digital Data ◽  
Light Sources ◽  
Light Emitting

As the demand for secure digital data continues to increase, image encryption and decryption have recently received tremendous attention. The rapid development of ultrathin metasurfaces has mainly been driven by the desire for the introduction of novel methods with which electromagnetic waves can be manipulated. As a promising application of metasurfaces, metalenses have shown great potential to replace bulky traditional optical devices. In this work, we present that the images produced by a commercially available projector are encrypted by using the color superposition principle, and the fabricated metalens is subsequently utilized to perform image decryption with an incidence made of white light-emitting diodes (LEDs). The correct positions for image decryption are carefully found by three distinct diode lasers as incident light sources. Recent investigations show that high-performance metalenses can be successfully developed once the suitable dielectric material is chosen. As a consequence, our metalens of high performance is composed of hexagon-resonated elements (HREs) made of gallium nitride (GaN) and is capable of resolving line width as small as 870 nm. The metalens with a smaller diameter of 8 μm is numerically simulated with a diffraction-limited focusing efficiency as high as 92%. This work once again shows that GaN metalenses, as future optics, have great prospects in expanding widespread applications in the near future.

Elastic Metasurfaces for Full Wavefront Control and Low-Frequency Energy Harvesting

2021 ◽  
pp. 1-22
Author(s):  
Zhenkun Lin ◽  
Serife Tol
Keyword(s):  
Energy Harvesting ◽  
Acoustic Waves ◽  
Focal Point ◽  
Numerical Models ◽  
Low Frequency ◽  
Single Layer ◽  
Theoretical Models ◽  
Propagation Path ◽  
Phase Gradient ◽  
Wave Amplification

Abstract Controlling and manipulating elastic/acoustic waves via artificially structured metamaterials, phononic crystals, and metasurfaces have gained an increasing research interest in the last decades. Unlike others, a metasurface is a single layer in the host medium with an array of subwavelength-scaled patterns introducing an abrupt phase shift in the wave propagation path. In this study, an elastic metasurface composed of an array of slender beam resonators is proposed to control the elastic wavefront of low-frequency flexural waves. The phase gradient based on the Snell's law is achieved by tailoring the thickness of thin beam resonators connecting two elastic host media. Through analytical and numerical models, the phase-modulated metasurfaces are designed and verified to accomplish three dynamic wave functions, namely, deflection, non-paraxial propagation, and focusing. An oblique incident wave is also demonstrated to show the versatility of the proposed design for focusing of wave energy incident from multiple directions. Experimentally measured focusing metasurface has nearly three times wave amplification at the designed focal point which validates the design and theoretical models. Furthermore, the focusing metasurface is exploited for low frequency energy harvesting and the piezoelectric harvester is improved by almost nine times in terms of the harvested power output as compared to the baseline harvester on the pure plate without metasurface.

Surface/interface nanoengineering for rechargeable Zn–air batteries

2020 ◽  
Vol 13 (4) ◽  
pp. 1132-1153 ◽  
Author(s):  
Tianpei Zhou ◽  
Nan Zhang ◽  
Changzheng Wu ◽  
Yi Xie
Keyword(s):  
High Performance ◽  
Rapid Development

Surface/interface nanoengineering of electrocatalysts and air electrodes will promote the rapid development of high-performance rechargeable Zn–air batteries.

High Performance Thin Layer Chromatography (HPTLC) for the Investigation of Medicinal Plants

2020 ◽  
Vol 16 ◽  
Author(s):  
Alper Gökbulut
Keyword(s):  
Medicinal Plants ◽  
High Performance ◽  
Separation Efficiency ◽  
Rapid Development ◽  
Herbal Remedies ◽  
Qualitative And Quantitative ◽  
Powerful Analytical Tool ◽  
Quantitative Examination ◽  
Data Acquisition And Processing ◽  
Layer Chromatography

Background: Chromatographic techniques such as TLC basically and, HPLC, GC, HPTLC equipped with various detectors are most frequently used for the qualitative and quantitative examination of herbals. Method: An overview of the recent literature concerning the usage of HPTLC for the analysis of medicinal plants has been reviewed. Results: During the last decade/s, HPTLC, a modern, sophisticated and automatized TLC technique with better and advanced separation efficiency, detection limit, data acquisition and processing, has been used for the analysis of herbal materials and preparations since the rapid development of technology in chromatography world. HPTLC with various detectors is a powerful analytical tool especially for the phytochemical applications such as herbal drug quantification and fingerprint analysis. Conclusion: In this review, a latest perspective has been established and some of the previous studies were summarized for the usage of HPTLC in the analysis of herbal remedies, dietary supplements and nutraceuticals.

Sign in / Sign up

Export Citation Format

Share Document