scholarly journals High-order multipoles in all-dielectric metagrating enabling ultralarge-angle light bending with unity efficiency

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Tie-Jun Huang ◽  
Li-Zheng Yin ◽  
Jin Zhao ◽  
Pu-Kun Liu
Keyword(s):  
High Efficiency ◽  
Negative Refraction ◽  
Beam Steering ◽  
Large Angle ◽  
Transverse Magnetic ◽  
Electric Polarization ◽  
High Order ◽  
Optical Diffraction ◽  
Optical Wave ◽  
Low Efficiency

Abstract Gradient metasurfaces have been extensively applied in the unprecedented control of light beams over thin optical components. However, these metasurfaces suffer from low efficiency when bending light through large angles and high fabrication demand when it requires fine discretion. In this work, we investigate all-dielectric metagratings based on the generalized Kerker effect induced by interference between Mie-type resonances. It allows extraordinary optical diffraction for beam steering through ultralarge angles. The coupling inside and between the lattices in the metagrating can be used to tune the excited states of the electric and magnetic resonances, including both the fundamental dipoles and high-order multipoles, leading to an ideal asymmetrical scattering pattern that redistributes the energy between the diffraction channels as required. The quadrupole and hexadecapole not only significantly enhance the working efficiency but also enable distinctive possibilities for wave manipulation that cannot be reached by dipoles. Utilizing a thin array of silicon rods, large-angle negative refraction and reflection are realized with almost unity efficiency under both transverse magnetic and transverse electric polarization. Compared with conventional metasurfaces, such an all-dielectric metagrating has the merits of high flexibility, high efficiency, and low fabrication requirements. The coupling and interactions among the multipoles may serve as a foundation for various forms of on-chip optical wave control.

scholarly journals Miniature planar telescopes for efficient, wide-angle, high-precision beam steering

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ziqian He ◽  
Kun Yin ◽  
Shin-Tson Wu
Keyword(s):  
Liquid Crystal ◽  
Optical Tweezers ◽  
High Precision ◽  
High Efficiency ◽  
Low Cost ◽  
Beam Steering ◽  
Large Angle ◽  
High Quality ◽  
Optical Elements ◽  
Optical Efficiency

AbstractNon-mechanical beam steerers with lightweight, compact, high-efficiency, high-precision, and/or large-angle are pivotal for light detection and ranging (LiDAR) of autonomous vehicles, eye-tracking for near-eye displays, microscopy, optical tweezers, and high-precision three-dimensional (3D) printing. However, even the most matured optical phased array can only provide quasi-continuous, efficient beam steering within a small angle range. A telescope module with an angle magnification function can be coupled to enlarge the steering range or precision. But obtaining a compact, low-cost, lightweight, high-quality telescope module with conventional optics remains challenging. Patterned liquid crystal-based planar optical elements offer great design freedom for manipulating the phase profile of light in 2D space. Owing to the advantages of high efficiency, thinness, low cost, easy processing, flexibility, and response to environmental stimuli, a plethora of high-quality optical devices have been demonstrated. Here, a miniature planar telescope mediated by liquid crystal polymers is proposed to offer angle magnification independent of incident spatial location. It consists of two cascaded liquid crystal planar optical elements, each performing a predefined mathematical transformation. By this concept, planar optical elements are fabricated using a new exposure method and assembled into planar telescopes with different magnification factors. Within the incident field range, over 84.6% optical efficiency is achieved with small wavefront distortion. Such a miniature planar telescope shows the potential of cascaded liquid crystal planar optical elements for realizing functionalities that cannot be fulfilled by single optical elements, and enables lightweight, low loss, passive optical transmitters for widespread applications.

scholarly journals Liquid Crystal Beam Steering Devices: Principles, Recent Advances, and Future Developments

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 292 ◽  
Author(s):  
Ziqian He ◽  
Fangwang Gou ◽  
Ran Chen ◽  
Kun Yin ◽  
Tao Zhan ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
High Efficiency ◽  
Response Times ◽  
Beam Steering ◽  
Polymer Network ◽  
Large Angle ◽  
Fast Response ◽  
Wide Field ◽  
Recent Advances ◽  
Optical Phased Array

Continuous, wide field-of-view, high-efficiency, and fast-response beam steering devices are desirable in a plethora of applications. Liquid crystals (LCs)—soft, bi-refringent, and self-assembled materials which respond to various external stimuli—are especially promising for fulfilling these demands. In this paper, we review recent advances in LC beam steering devices. We first describe the general operation principles of LC beam steering techniques. Next, we delve into different kinds of beam steering devices, compare their pros and cons, and propose a new LC-cladding waveguide beam steerer using resistive electrodes and present our simulation results. Finally, two future development challenges are addressed: Fast response time for mid-wave infrared (MWIR) beam steering, and device hybridization for large-angle, high-efficiency, and continuous beam steering. To achieve fast response times for MWIR beam steering using a transmission-type optical phased array, we develop a low-loss polymer-network liquid crystal and characterize its electro-optical properties.

scholarly journals On-chip trans-dimensional plasmonic router

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3357-3365 ◽  
Author(s):  
Shaohua Dong ◽  
Qing Zhang ◽  
Guangtao Cao ◽  
Jincheng Ni ◽  
Ting Shi ◽  
...  
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Incident Angle ◽  
Reciprocal Lattice ◽  
Plasmonic Waveguide ◽  
Optical Diffraction ◽  
Local Dynamic ◽  
Phase Gradient ◽  
On Chip ◽  
Plasmon Polaritons

AbstractPlasmons, as emerging optical diffraction-unlimited information carriers, promise the high-capacity, high-speed, and integrated photonic chips. The on-chip precise manipulations of plasmon in an arbitrary platform, whether two-dimensional (2D) or one-dimensional (1D), appears demanding but non-trivial. Here, we proposed a meta-wall, consisting of specifically designed meta-atoms, that allows the high-efficiency transformation of propagating plasmon polaritons from 2D platforms to 1D plasmonic waveguides, forming the trans-dimensional plasmonic routers. The mechanism to compensate the momentum transformation in the router can be traced via a local dynamic phase gradient of the meta-atom and reciprocal lattice vector. To demonstrate such a scheme, a directional router based on phase-gradient meta-wall is designed to couple 2D SPP to a 1D plasmonic waveguide, while a unidirectional router based on grating metawall is designed to route 2D SPP to the arbitrarily desired direction along the 1D plasmonic waveguide by changing the incident angle of 2D SPP. The on-chip routers of trans-dimensional SPP demonstrated here provide a flexible tool to manipulate propagation of surface plasmon polaritons (SPPs) and may pave the way for designing integrated plasmonic network and devices.

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

Genetics ◽  
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.

scholarly journals A Brief Review on Solvent-Free Synthesis of Zeolites

Materials ◽  
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.

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

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.

scholarly journals Large angle beam steering THz antenna using active frequency selective surface based on hybrid graphene-gold structure

2018 ◽  
Vol 26 (12) ◽  
pp. 15353 ◽  
Author(s):  
Bian Wu ◽  
Yue Hu ◽  
Yu Tong Zhao ◽  
Wei Bing Lu ◽  
Wei Zhang
Keyword(s):  
Beam Steering ◽  
Large Angle ◽  
Frequency Selective Surface ◽  
Frequency Selective ◽  
Thz Antenna

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

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
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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