High-efficiency Bessel beam array generation by Huygens metasurfaces

AbstractBessel beams have attracted considerable interest because of their unique non-diffractive, self-healing characteristics. Different approaches have been proposed to generate Bessel beams, such as using axicons, diffractive optical elements, composite holograms, or spatial light modulators. However, these approaches have suffered from limited numerical aperture, low efficiency, polarization-dependent properties, etc. Here, by utilizing dielectric Huygens metasurfaces as ultrathin, compact platforms by integrating the functionalities of Dammann gratings and axicons, we successfully demonstrate multiple Bessel beam generation with polarization-independent property. The number of two-dimensional arrays can be controlled flexibly, which can enhance information capacity with a total efficiency that can reach 66.36%. This method can have various applications, such as parallel laser fabrication, efficient optical tweezers, and optical communication.

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Generation of Multiple Pseudo Bessel Beams with Accurately Controllable Propagation Directions and High Efficiency Using a Reflective Metasurface

Applied Sciences ◽

10.3390/app10207219 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7219

Author(s):

Haixia Liu ◽

Hao Xue ◽

Yongjie Liu ◽

Long Li

Keyword(s):

Electromagnetic Waves ◽

High Efficiency ◽

Superposition Principle ◽

Bessel Beam ◽

Large Angle ◽

Propagation Distance ◽

Wireless Power ◽

Bessel Beams ◽

Full Wave ◽

Measurement Results

In this paper, a generation method procedure based on a reflective metasurface is proposed to generate multiple pseudo Bessel beams with accurately controllable propagation directions and high efficiency. Firstly, by adjusting the miniaturized unit cell of the reflective metasurface to modulate the electromagnetic waves using the proposed method, some off-axis pseudo Bessel beams with different propagation directions are generated. Then, by achieving the large-angle deflection and comparing the results with previous existing methods, the superiority of the proposed method is demonstrated. Based on the generated single off-axis pseudo Bessel beam and the superposition principle of the electromagnetic wave, a reflective metasurface with 47 × 47 elements is designed and fabricated at 10 GHz to generate dual pseudo Bessel beams. Full-wave simulation and experimental measurement results validate that the dual pseudo Bessel beams were generated successfully. The propagation directions of the dual pseudo Bessel beams can be controlled accurately by the reflective metasurface, and the efficiency of the beams is 59.2% at a propagation distance of 400 mm. The energy of the beams keeps concentrating along the propagation axes, which provides a new choice for wireless power transfer and wireless communication with one source to multiple receiving targets.

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Broadband and high-efficiency accelerating beam generation by dielectric catenary metasurfaces

Nanophotonics ◽

10.1515/nanoph-2020-0057 ◽

2020 ◽

Vol 9 (9) ◽

pp. 2829-2837 ◽

Cited By ~ 2

Author(s):

Fei Zhang ◽

Qingyu Zeng ◽

Mingbo Pu ◽

Yanqin Wang ◽

Yinghui Guo ◽

...

Keyword(s):

Electromagnetic Waves ◽

High Efficiency ◽

Spectral Band ◽

Subwavelength Structures ◽

Self Healing ◽

Infrared Band ◽

Phase Gradient ◽

Beam Generation ◽

Large Phase ◽

Low Efficiency

AbstractSelf-accelerating beams show considerable captivating phenomena and applications owing to their transverse acceleration, diffraction-free and self-healing properties in free space. Metasurfaces consisting of dielectric or metallic subwavelength structures attract enormous attention to acquire self-accelerating beams, owing to their extraordinary capabilities in the arbitrary control of electromagnetic waves. However, because the self-accelerating beam generator possesses a large phase gradient, traditional discrete metasurfaces suffer from insufficient phase sampling, leading to a low efficiency and narrow spectral band. To overcome this limitation, a versatile platform of catenary-inspired dielectric metasurfaces is proposed to endow arbitrary continuous wavefronts. A high diffraction efficiency approaching 100% is obtained in a wide spectral range from 9 to 13 μm. As a proof-of-concept demonstration, the broadband, high-efficiency and high-quality self-accelerating beam generation is experimentally verified in the infrared band. Furthermore, the chiral response of the proposed metasurfaces enables the spin-controlled beam acceleration. Considering these superior performances, this design methodology may find wide applications in particle manipulation, high-resolution imaging, optical vortex generation, and so forth.

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Bessel Beam: Significance and Applications—A Progressive Review

Micromachines ◽

10.3390/mi11110997 ◽

2020 ◽

Vol 11 (11) ◽

pp. 997

Author(s):

Svetlana Nikolaevna Khonina ◽

Nikolay Lvovich Kazanskiy ◽

Sergey Vladimirovich Karpeev ◽

Muhammad Ali Butt

Keyword(s):

Optical Communication ◽

Review Paper ◽

Bessel Beam ◽

Gaussian Beams ◽

Self Healing ◽

Long Distance ◽

Bessel Beams ◽

Wave Nature ◽

Sharp Focusing ◽

Commercial Applications

Diffraction is a phenomenon related to the wave nature of light and arises when a propagating wave comes across an obstacle. Consequently, the wave can be transformed in amplitude or phase and diffraction occurs. Those parts of the wavefront avoiding an obstacle form a diffraction pattern after interfering with each other. In this review paper, we have discussed the topic of non-diffractive beams, explicitly Bessel beams. Such beams provide some resistance to diffraction and hence are hypothetically a phenomenal alternate to Gaussian beams in several circumstances. Several outstanding applications are coined to Bessel beams and have been employed in commercial applications. We have discussed several hot applications based on these magnificent beams such as optical trapping, material processing, free-space long-distance self-healing beams, optical coherence tomography, superresolution, sharp focusing, polarization transformation, increased depth of focus, birefringence detection based on astigmatic transformed BB and encryption in optical communication. According to our knowledge, each topic presented in this review is justifiably explained.

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Planar efficient metasurface for generation of Bessel beam and super-resolution focusing

Optical and Quantum Electronics ◽

10.1007/s11082-021-02765-7 ◽

2021 ◽

Vol 53 (3) ◽

Author(s):

Dancui Li ◽

Xiaorui Wang ◽

Jinzhong Ling ◽

Ying Yuan

Keyword(s):

Topological Charge ◽

Bessel Beam ◽

Super Resolution ◽

Visible Spectrum ◽

Optical Devices ◽

Zero Order ◽

Optical Manipulation ◽

Bessel Beams ◽

Laser Fabrication ◽

Low Efficiency

AbstractIn this paper, we propose a device generating Bessel beam that can assist microscope to enhance resolution of microscope to λ/3. As the conventional optical devices of generating Bessel beam have some drawbacks, such as low efficiency, and bulky volume, we design plane-axicons for generating Bessel beam using the principle of phase superposition. The designed plane-axicons can generate Bessel beams with zero-order and higher-order by changing topological charge n. We also demonstrate the FWHMs of plane-axicons about as small as λ/3 and have FWHMs with weak fluctuations independent of wavelength across the visible spectrum, which means the Bessel beam can be used to increase resolution of microscope. These performances make the plane-axicons can also enable other advanced research and applications related to Bessel beams ranging from laser fabrication to optical manipulation.

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Generation of high-uniformity and high-resolution Bessel beam arrays through all-dielectric metasurfaces

Nanophotonics ◽

10.1515/nanoph-2021-0603 ◽

2022 ◽

Vol 0 (0) ◽

Author(s):

Lei Chen ◽

Saima Kanwal ◽

Binbin Yu ◽

Jijun Feng ◽

Chunxian Tao ◽

...

Keyword(s):

High Resolution ◽

Data Storage ◽

Bessel Beam ◽

Numerical Aperture ◽

Transverse Dimension ◽

Sampling Theorem ◽

Spatial Light Modulators ◽

Imaging Data ◽

Light Modulators ◽

High Uniformity

Abstract Bessel beam arrays are progressively attracting attention in recent years due to their remarkable non-diffracting nature and parallel manipulation capabilities in diverse applications. However, the poor phase discretization of conventional approaches such as spatial light modulators leads to low numerical aperture (NA) beam arrays due to the limitation imposed by the Nyquist sampling theorem and poor uniformity of the beam intensity. The key contribution of this study is to experimentally demonstrate the generation of high-uniformity and high-resolution Bessel beam arrays by utilizing all-dielectric metasurfaces. This is attained by optimizing the design of the supercell of a Dammann grating, particularly decreasing each supercell of the grating to a proper size. We demonstrate a 4 × 4 array of Bessel beams with a subwavelength transverse dimension (570 nm, ∼0.9λ) and a large NA of 0.4 for each beam in the array, while maintaining a relatively high uniformity intensity (52.40%) for the array. Additionally, the Bessel beam arrays are generated in a broadband range through the proposed all-dielectric metasurfaces. Our results are of great significance and particularly useful for applications of metasurface-based Bessel beam arrays in multidisciplinary fields such as laser fabrication, biomedical imaging, data storage, and multi-particle trapping.

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CHROMOSOMAL BASIS OF THE MEROZYGOSITY IN A PARTIALLY DIPLOID MUTANT OF PNEUMOCOCCUS

Genetics ◽

10.1093/genetics/80.4.667 ◽

1975 ◽

Vol 80 (4) ◽

pp. 667-678

Author(s):

Mary Lee S Ledbetter ◽

Rollin D Hotchkiss

Keyword(s):

High Efficiency ◽

Point Mutations ◽

Resistant Mutant ◽

Chromosomal Marker ◽

Structural Abnormality ◽

C Cells ◽

Wild Type ◽

Chromosomal Locus ◽

Low Efficiency ◽

Derivatives Of

ABSTRACT A sulfonamide-resistant mutant of pneumococcus, sulr-c, displays a genetic instability, regularly segregating to wild type. DNA extracts of derivatives of the strain possess transforming activities for both the mutant and wild-type alleles, establishing that the strain is a partial diploid. The linkage of sulr-c to strr-61, a stable chromosomal marker, was established, thus defining a chromosomal locus for sulr-c. DNA isolated from sulr-c cells transforms two mutant recipient strains at the same low efficiency as it does a wild-type recipient, although the mutant property of these strains makes them capable of integrating classical "low-efficiency" donor markers equally as efficiently as "high efficiency" markers. Hence sulr-c must have a different basis for its low efficiency than do classical low efficiency point mutations. We suggest that the DNA in the region of the sulr-c mutation has a structural abnormality which leads both to its frequent segregation during growth and its difficulty in efficiently mediating genetic transformation.

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A Brief Review on Solvent-Free Synthesis of Zeolites

Materials ◽

10.3390/ma14040788 ◽

2021 ◽

Vol 14 (4) ◽

pp. 788

Author(s):

Jinlin Mei ◽

Aijun Duan ◽

Xilong Wang

Keyword(s):

High Efficiency ◽

Raw Materials ◽

Solvent Free ◽

High Yield ◽

Control Synthesis ◽

Mechanical Mixing ◽

Synthesis Mechanism ◽

Wastewater Pollution ◽

Low Efficiency ◽

Solvent Free Synthesis

The traditional hydrothermal method to prepare zeolite will inevitably use a large amount of water as a solvent, which will lead to higher autogenous pressure, low efficiency, and wastewater pollution. The solvent-free method can be used to synthesize various types of zeolites by mechanical mixing, grinding, and heating of solid raw materials, which exhibits the apparent advantages of high yield, low pollution, and high efficiency. This review mainly introduces the development process of solvent-free synthesis, preparation of hierarchical zeolite, morphology control, synthesis mechanism and applications of solvent-free methods. It can be believed that solvent-free methods will become a research focus and have enormous industrial application potential.

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Inflight Transmission of COVID-19 Based on Experimental Aerosol Dispersion Data

Journal of Travel Medicine ◽

10.1093/jtm/taab023 ◽

2021 ◽

Author(s):

Zhaozhi Wang ◽

Edwin R Galea ◽

Angus Grandison ◽

John Ewer ◽

Fuchen Jia

Keyword(s):

High Efficiency ◽

Face Mask ◽

Generation Rate ◽

Aviation Industry ◽

Filtration System ◽

Dispersion Data ◽

Low Probability ◽

Meal Service ◽

Low Efficiency ◽

Aerosol Dispersion

Abstract Background An issue of concern to the travelling public is the possibility of in-flight transmission of COVID-19 during long- and short-haul flights. The aviation industry maintains that the probability of contracting the illness is small based on reported cases, modelling and data from aerosol dispersion experiments conducted on-board aircraft. Methods Using experimentally derived aerosol dispersion data for a B777–200 aircraft and a modified version of the Wells-Riley equation we estimate inflight infection probability for a range of scenarios involving quanta generation rate and face mask efficiency. Quanta generation rates were selected based on COVID-19 events reported in the literature while mask efficiency was determined from the aerosol dispersion experiments. Results The MID-AFT cabin exhibits the highest infection probability. The calculated maximum individual infection probability (without masks) for a 2-hour flight in this section varies from 4.5% for the ‘Mild Scenario’ to 60.2% for the ‘Severe Scenario’ although the corresponding average infection probability varies from 0.1% to 2.5%. For a 12-hour flight, the corresponding maximum individual infection probability varies from 24.1% to 99.6% and the average infection probability varies from 0.8% to 10.8%. If all passengers wear face masks throughout the 12-hour flight, the average infection probability can be reduced by approximately 73%/32% for high/low efficiency masks. If face masks are worn by all passengers except during a one-hour meal service, the average infection probability is increased by 59%/8% compared to the situation where the mask is not removed. Conclusions This analysis has demonstrated that while there is a significant reduction in aerosol concentration due to the nature of the cabin ventilation and filtration system, this does not necessarily mean that there is a low probability or risk of in-flight infection. However, mask wearing, particularly high-efficiency ones, significantly reduces this risk.

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Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

Scientific Reports ◽

10.1038/s41598-020-72668-2 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Chun-Yuan Fan ◽

Chia-Ping Lin ◽

Guo-Dung J. Su

Keyword(s):

High Efficiency ◽

Numerical Aperture ◽

Vital Role ◽

Optical Systems ◽

Wide Field ◽

Wide Angle ◽

Camera Systems ◽

Single Lens ◽

Hexagonal Arrangement ◽

Virtual And Augmented Reality

Abstract Wide-angle optical systems play a vital role in imaging applications and have been researched for many years. In traditional lenses, attaining a wide field of view (FOV) by using a single optical component is difficult because these lenses have crucial aberrations. In this study, we developed a wide-angle metalens with a numerical aperture of 0.25 that provided a diffraction-limited FOV of over 170° for a wavelength of 532 nm without the need for image stitching or multiple lenses. The designed wide-angle metalens is free of aberration and polarization, and its full width of half maximum is close to the diffraction limit at all angles. Moreover, the metalens which is designed through a hexagonal arrangement exhibits higher focusing efficiency at all angles than most-seen square arrangement. The focusing efficiencies are as high as 82% at a normal incident and 45% at an incident of 85°. Compared with traditional optical components, the proposed metalens exhibits higher FOV and provides a more satisfactory image quality because of aberration correction. Because of the advantages of the proposed metalens, which are difficult to achieve for a traditional single lens, it has the potential to be applied in camera systems and virtual and augmented reality.

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High Efficiency Generalized Parallel Counters for Look-Up Table Based FPGAs

International Journal of Reconfigurable Computing ◽

10.1155/2015/518272 ◽

2015 ◽

Vol 2015 ◽

pp. 1-16 ◽

Cited By ~ 4

Author(s):

Burhan Khurshid ◽

Roohie Naaz Mir

Keyword(s):

Power Dissipation ◽

High Speed ◽

High Efficiency ◽

Critical Path ◽

Fir Filters ◽

Path Delay ◽

Look Up Table ◽

Improved Performance ◽

Ip Cores ◽

Low Efficiency

Generalized parallel counters (GPCs) are used in constructing high speed compressor trees. Prior work has focused on utilizing the fast carry chain and mapping the logic onto Look-Up Tables (LUTs). This mapping is not optimal in the sense that the LUT fabric is not fully utilized. This results in low efficiency GPCs. In this work, we present a heuristic that efficiently maps the GPC logic onto the LUT fabric. We have used our heuristic on various GPCs and have achieved an improvement in efficiency ranging from 33% to 100% in most of the cases. Experimental results using Xilinx 5th-, 6th-, and 7th-generation FPGAs and Stratix IV and V devices from Altera show a considerable reduction in resources utilization and dynamic power dissipation, for almost the same critical path delay. We have also implemented GPC-based FIR filters on 7th-generation Xilinx FPGAs using our proposed heuristic and compared their performance against conventional implementations. Implementations based on our heuristic show improved performance. Comparisons are also made against filters based on integrated DSP blocks and inherent IP cores from Xilinx. The results show that the proposed heuristic provides performance that is comparable to the structures based on these specialized resources.

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