scholarly journals Dirac fermion metagratings in graphene

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Pengcheng Wan ◽  
Yinghui Ren ◽  
Qianjing Wang ◽  
Di Huang ◽  
Ling Zhou ◽  
...  
Keyword(s):  
Beam Steering ◽  
Large Angle ◽  
High Mobility ◽  
Diffraction Order ◽  
Beam Deflection ◽  
Dirac Fermion ◽  
Angle Of Incidence ◽  
New Paradigm ◽  
Whispering Gallery ◽  
Electronic Holography

AbstractWe theoretically demonstrate a Dirac fermion metagrating which is an artificially engineered material in graphene. Although its physics mechanism is different from that of optical metagrating, both of them can deliver waves to one desired diffraction order. Here we design the metagrating as a linear array of bias-tunable quantum dots to engineer electron beams to travel along the -1st-order transmission direction with unity efficiency. Equivalently, electron waves are deflected by an arbitrary large-angle ranging from 90° to 180° by controlling the bias. The propagation direction changes abruptly without the necessity of a large transition distance. This effect is irrelevant to complete band gaps and thus the advantages of graphene with high mobility are not destroyed. This can be attributed to the whispering-gallery modes, which evolve with the angle of incidence to completely suppress the other diffraction orders supported by the metagrating and produce unity-efficiency beam deflection by enhancing the -1st transmitted diffraction order. The concept of Dirac fermion metagratings opens up a new paradigm in electron beam steering and could be applied to achieve two-dimensional electronic holography.

scholarly journals Phase-only transmissive spatial light modulator based on tunable dielectric metasurface

Science ◽  
2019 ◽  
Vol 364 (6445) ◽  
pp. 1087-1090 ◽  
Author(s):  
Shi-Qiang Li ◽  
Xuewu Xu ◽  
Rasna Maruthiyodan Veetil ◽  
Vytautas Valuckas ◽  
Ramón Paniagua-Domínguez ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Light Modulator ◽  
Deflection Angle ◽  
Beam Steering ◽  
Beam Deflection ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Steering Angle ◽  
Holographic Display ◽  
Light Modulators

Rapidly developing augmented reality, solid-state light detection and ranging (LIDAR), and holographic display technologies require spatial light modulators (SLMs) with high resolution and viewing angle to satisfy increasing customer demands. Performance of currently available SLMs is limited by their large pixel sizes on the order of several micrometers. Here, we propose a concept of tunable dielectric metasurfaces modulated by liquid crystal, which can provide abrupt phase change, thus enabling pixel-size miniaturization. We present a metasurface-based transmissive SLM, configured to generate active beam steering with >35% efficiency and a large beam deflection angle of 11°. The high resolution and steering angle obtained provide opportunities to develop the next generation of LIDAR and display technologies.

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

Large-angle beam deflection of a laser-cooled sodium beam

1989 ◽  
Vol 6 (11) ◽  
pp. 2149 ◽  
Author(s):  
J. Nellessen ◽  
J. H. Müller ◽  
K. Sengstock ◽  
W. Ertmer
Keyword(s):  
Large Angle ◽  
Beam Deflection ◽  
Sodium Beam

scholarly journals Multifunctional Gratings for Multiband Spatial Filtering, Retroreflection, Splitting and Demultiplexing Based on C2 Symmetric Photonic Crystals

2021 ◽  
Author(s):  
Andriy E. Serebryannikov ◽  
Diana C. Skigin ◽  
Guy A. E. Vandenbosch ◽  
Ekmel Ozbay
Keyword(s):  
Photonic Crystals ◽  
Specular Reflection ◽  
Diffraction Order ◽  
Spatial Filtering ◽  
Frequency Variation ◽  
Angle Of Incidence ◽  
Reflection Mode ◽  
Negative Order ◽  
Wide Range ◽  
Incident Wave Energy

Abstract The concept of multifunctional reflection-mode gratings based on rod-type photonic crystals with C2 symmetry is introduced and examined. The specific modal properties lead to the vanishing dependence of the first-negative-order maximum on the angle of incidence within a wide range, and the nearly sinusoidal redistribution of the incident-wave energy between zero order (specular reflection) and first negative diffraction order (deflection) at frequency variation that are the key features enabling various functionalities in one structure and functionality merging. The elementary functionalities offered by the studied structures, of which multifunctional scenarios can be designed, include but are not restricted to multiband spatial filtering, multiband splitting, and demultiplexing. The proposed structures are shown to be capable in multifunctional operation in case of an obliquely incident polychromatic wave. The generalized demultiplexing is demonstrated for the case when several polychromatic wavesare incident at different angles. The same deflection properties yield multiband splitting, and merging demultiplexing and splitting functionalties in one functionality, which may contribute to various multifunctional scenarios. The proposed gratings arealso studied in transmissive configuration.

Large angle beam steering using a slanted holographic polymer dispersed liquid crystal grating

2018 ◽  
Vol 51 (38) ◽  
pp. 385103 ◽  
Author(s):  
Minghuan Liu ◽  
Zhihui Diao ◽  
Li Xuan ◽  
Zenghui Peng ◽  
Lishuang Yao ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Beam Steering ◽  
Large Angle ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Liquid Crystal Grating

Introduction to Fog Computing

2019 ◽  
pp. 1-35
Author(s):  
Stojan Kitanov ◽  
Toni Janevski
Keyword(s):  
Cloud Computing ◽  
Data Storage ◽  
Fog Computing ◽  
High Mobility ◽  
End Users ◽  
Mobile Edge Computing ◽  
New Paradigm ◽  
Research Directions ◽  
Intelligent Networking ◽  
High Scalability

Pushing computing, control, data storage, and processing into the cloud has been a key trend in the past decade. However, the cloud alone encounters growing limitations, such as reduced latency, high mobility, high scalability, and real-time execution in order to meet the upcoming computing and intelligent networking demands. A new paradigm called fog computing has emerged to overcome these limits. Fog extends cloud computing and services to the edge of the network. It provides data, computing, storage, and application services to end-users that can be hosted at the network edge. It reduces service latency, and improves QoS/QoE, that results in superior user experience. This chapter is about introduction and overview of fog computing, comparison between fog computing and cloud computing, fog computing and mobile edge computing, possible fog computing architecture, applications of fog computing, and possible research directions.

Quality Evaluation of Cloud and Fog Computing Services in 5G Networks

2019 ◽  
pp. 1-36 ◽  
Author(s):  
Stojan Kitanov ◽  
Borislav Popovski ◽  
Toni Janevski
Keyword(s):  
Network Performance ◽  
Fog Computing ◽  
High Mobility ◽  
Network Control ◽  
5G Networks ◽  
New Paradigm ◽  
Network Function ◽  
Computing Services ◽  
5G Network ◽  
Intelligent Networking

Because of the increased computing and intelligent networking demands in 5G network, cloud computing alone encounters too many limitations, such as requirements for reduced latency, high mobility, high scalability, and real-time execution. A new paradigm called fog computing has emerged to resolve these issues. Fog computing distributes computing, data processing, and networking services to the edge of the network, closer to end users. Fog applied in 5G significantly improves network performance in terms of spectral and energy efficiency, enable direct device-to-device wireless communications, and support the growing trend of network function virtualization and separation of network control intelligence from radio network hardware. This chapter evaluates the quality of cloud and fog computing services in 5G network, and proposes five algorithms for an optimal selection of 5G RAN according to the service requirements. The results demonstrate that fog computing is a suitable technology solution for 5G networks.

Extremely large-angle beam deflection based on low-index sparse dielectric metagratings

2020 ◽  
Vol 53 (24) ◽  
pp. 245101 ◽  
Author(s):  
Xipu Dong ◽  
Jierong Cheng ◽  
Fei Fan ◽  
Ziyang Zhang ◽  
Yan Liu ◽  
...  
Keyword(s):  
Large Angle ◽  
Beam Deflection

scholarly journals Liquid Droplet Microresonators

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 473 ◽  
Author(s):  
Antonio Giorgini ◽  
Saverio Avino ◽  
Pietro Malara ◽  
Paolo De Natale ◽  
Gianluca Gagliardi
Keyword(s):  
Acoustic Waves ◽  
Near Infrared ◽  
Liquid Droplet ◽  
Scattered Light ◽  
Surface Acoustic Waves ◽  
Optical Quality ◽  
Whispering Gallery Modes ◽  
New Paradigm ◽  
Frequency Locking ◽  
Whispering Gallery

We provide here an overview of passive optical micro-cavities made of droplets in the liquid phase. We focus on resonators that are naturally created and suspended under gravity thanks to interfacial forces, illustrating simple ways to excite whispering-gallery modes in various slow-evaporation liquids using free-space optics. Similar to solid resonators, frequency locking of near-infrared and visible lasers to resonant modes is performed exploiting either phase-sensitive detection of the leakage cavity field or multiple interference between whispering-gallery modes in the scattered light. As opposed to conventional micro-cavity sensors, each droplet acts simultaneously as the sensor and the sample, whereby the internal light can detect dissolved compounds and particles. Optical quality factors up to 107–108 are observed in liquid-polymer droplets through photon lifetime measurements. First attempts in using single water droplets are also reported. These achievements point out their huge potential for direct spectroscopy and bio-chemical sensing in liquid environments. Finally, the first experiments of cavity optomechanics with surface acoustic waves in nanolitre droplets are presented. The possibility to perform studies of viscous-elastic properties points to a new paradigm: a droplet device as an opto-fluid-mechanics laboratory on table-top scale under controlled environmental conditions.

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