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Silicon slot metasurface supporting a multitude of bound states in the continuum: theoretical and experimental studies

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Optics & Laser Technology 2025年 192卷

作者： G. Nousios J.F. Algorri W. Fuscaldo F. Dell’Olio S. Romano G. Zito B. Miranda Y. Ding V. Dmitriev L.C. Andreani M. Galli O. Tsilipakos E.E. Kriezis D.C. Zografopoulos Consiglio Nazionale delle Ricerche Istituto per la Microelettronica e Microsistemi (CNR-IMM) Rome 00133 Italy Photonics Engineering Group University of Cantabria Santander 39005 Spain CIBER-bbn Instituto de Salud Carlos III Madrid 28029 Spain Instituto de Investigación Sanitaria Valdecilla (IDIVAL) Santander 39011 Spain Department of Electrical and Information Engineering Polytecnic University of Bari Bari 70125 Italy CNR ISASI Institute of Applied Sciences and Intelligent Systems Naples 80078 Italy SiPhotonIC ApS Virum Stationsvej 207 Virum 2830 Denmark Department of Electrical and Photonics Engineering Technical University of Denmark Ørsteds Plads Bygning 343 Kongens Lyngby 2800 Denmark Electrical Engineering Department Federal University of Pará Belém 66075-900 Brazil Dipartimento di Fisica Università di Pavia Pavia 27100 Italy Theoretical and Physical Chemistry Institute National Hellenic Research Foundation Athens GR-11635 Greece School of Electrical and Computer Engineering Aristotle University of Thessaloniki (AUTH) Thessaloniki GR-54124 Greece

A dielectric metasurface supporting a variety of quasi-bound states in the continuum (qBICs), including the intricate dark toroidal dipole and toroidal quadrupole Mie modes, is theoretically and experimentally investigated in the near-infrared. The metasurface consists of square slots etched into a thin silicon layer and periodically arrayed in a subdiffractive lattice residing on a sapphire substrate. The modal properties of the qBICs, i.e., the quality factors alongside the near- and far-field characteristics, are comprehensively assessed through a set of theoretical tools, including eigenfrequency simulations and multipolar expansion analysis. The results are corroborated by experimental studies verifying the existence of the qBICs. The investigated metasurface may serve as an ideal platform for nonlinear applications, such as third-harmonic generation, when leveraging the Kerr effect of silicon, as well as for lasing when the slot is filled with a low-index material hosting organic dye molecules.

关键词： Silicon metasurfaces Bound states in the continuum Nanofabrication Multipole analysis Metasurface lasers Nonlinear nanophotonics

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An optimality gap test for a semidefinite relaxation of a quadratic program with two quadratic constraints

arXiv

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arXiv 2019年

作者： Cheng, Sheng Martins, Nuno C. Department of Electrical and Computer Engineering and Institute for Systems Research University of Maryland College ParkMD United States

We propose a necessary and sufficient test to determine whether a solution for a general quadratic program with two quadratic constraints (QC2QP) can be computed from that of a specific convex semidefinite relaxation, in which case we say that there is no optimality gap. Originally intended to solve a nonconvex optimal control problem, we consider the case in which the cost and both constraints of the QC2QP may be nonconvex. We obtained our test, which also ascertains when strong duality holds, by generalizing a closely-related method by Ai and Zhang. An extension was necessary because, while the method proposed by Ai and Zhang also allows for two quadratic constraints, it requires that at least one is strictly convex. In order to illustrate the usefulness of our test, we applied it to two examples that do not satisfy the assumptions required by prior methods. Our test guarantees that there is no optimality gap for the first example-a solution is also computed from the relaxation-and we used it to establish that an optimality gap exists in the second. Copyright © 2019, The Authors. All rights reserved.

关键词： Quadratic programming

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Self-Propelled Detachment upon Coalescence of Surface Bubbles

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Physical Review Letters 2021年第23期127卷 235501-235501页

作者： Pengyu Lv Pablo Peñas Hai Le The Jan Eijkel Albert van den Berg Xuehua Zhang Detlef Lohse State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science Beijing Innovation Center for Engineering Science and Advanced Technology College of Engineering Peking University Beijing 100871 People’s Republic of China Physics of Fluids group Faculty of Science and Technology Max Planck—University of Twente Center for Complex Fluid Dynamics MESA+Institute and J. M. Burgers Centre for Fluid Dynamics University of Twente P.O. Box 217 7500 AE Enschede Netherlands BIOS Lab-on-a-Chip group Faculty of Electrical Engineering Max Planck—University of Twente Center for Complex Fluid Dynamics Mathematics and Computer Science MESA+Institute University of Twente P.O. Box 217 7500 AE Enschede Netherlands Department of Chemical & Materials Engineering University of Alberta Edmonton Alberta T6G1H9 Canada Max Planck Institute for Dynamics and Self-Organization 37077 Göttingen Germany

The removal of microbubbles from substrates is crucial for the efficiency of many catalytic and electrochemical gas evolution reactions in liquids. The current work investigates the coalescence and detachment of bubbles generated from catalytic decomposition of hydrogen peroxide. Self-propelled detachment, induced by the coalescence of two bubbles, is observed at sizes much smaller than those determined by buoyancy. Upon coalescence, the released surface energy is partly dissipated by the bubble oscillations, working against viscous drag. The remaining energy is converted to the kinetic energy of the out-of-plane jumping motion of the merged bubble. The critical ratio of the parent bubble sizes for the jumping to occur is theoretically derived from an energy balance argument and found to be in agreement with the experimental results. The present results provide both physical insight for the bubble interactions and practical strategies for applications in chemical engineering and renewable energy technologies like electrolysis.

关键词： Drops & bubbles

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Multiple-association supporting htc/mtc in limited-backhaul capacity Ultra-Dense Networks

arXiv

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arXiv 2020年

作者： Elbayoumi, Mohammed Hamouda, Walaa Youssef, Amr Concordia Institute for Information Systems Engineering Concordia University MontrealQCH3G 1M8 Canada The Department of Electrical and Computer Engineering Concordia University MontrealQCH3G 1M8 Canada

Coexistence of Human-Type Communications (HTCs) and Machine-Type Communications (MTCs) is inevitable. Ultra-Dense Networks (UDNs) will be efficacious in supporting both types of communications. In a UDN, a massive number of low-power and low-cost Small Cells (SCs) are deployed with density higher than that of the HTC users. In such a scenario, the backhaul capacities constitute an intrinsic bottleneck for the system. Hence, we propose a multiple association scheme where each HTC user associates to and activates multiple SCs to overcome the backhaul capacity constraints. In addition, having more active cells allows for more MTC devices to be supported by the network. Using tools from stochastic geometry, we formulate a novel mathematical framework investigating the performance of the limited-backhaul capacity UDN in terms of Area Spectral Efficiency (ASE) for both HTC and MTC and the density of supported MTC devices. Extensive simulations were conducted to verify the accuracy of the mathematical analysis under different system parameters. Results show the existence of an optimum number of SCs to which an HTC user may connect under backhaul capacity constraints. Besides, the proposed multiple association scheme significantly improves the performance of MTC in terms of both ASE and density of supported devices. Copyright © 2020, The Authors. All rights reserved.

关键词： Geometry

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Power Minimization Via Rate Splitting in Downlink Cloud-Radio Access Networks

Power Minimization Via Rate Splitting in Downlink Cloud-Radi...

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IEEE International Conference on Communications Workshops, ICC

作者： Alaa Alameer Ahmad Hayssam Dahrouj Anas Chaaban Aydin Sezgin Tareq Y. Al-Naffouri Mohamed-Slim Alouini Institute of Digital Communication Systems Ruhr-Universität Bochum Germany Department of Electrical and Computer Engineering Effat University Saudi Arabia School of Engineering The University of British Columbia Kelowna Canada Communication Theory Lab King Abdullah University of Science and Technology Thuwal Saudi Arabia

ISBN: (数字)9781728174402

ISBN: (纸本)9781728174419

Minimizing the power consumption in mobile communication networks while guaranteeing quality of service (QoS) requirements is essential in light of the unprecedented increase in the number of connected devices and the associated data traffic. Conventional cloud-radio access networks (C-RAN) assume treating interference as noise (TIN) while dealing with the provisioning of wireless interference. This paper considers a C-RAN system, where a central processor (CP) at the cloud is connected to several base-stations (BSs) via limited capacity fronthaul links. The paper then assumes a communication scheme where the CP applies rate splitting (RS) to the messages requested by the users, and enables common message decoding (CMD) at the receivers side. The paper addresses the problem of minimizing the weighted transmit power subject to minimum QoS and fronthaul capacity constraints, which is generally a non-convex and difficult problem to solve. We, therefore, propose an iterative approach based on inner-convex approximations (ICA) to obtain a stationary point of the optimization problem. The simulations show the power savings achieved by the proposed RS-CMD scheme as compared to the conventional TIN, especially at high QoS requirements.

关键词： Quality of service Decoding Interference Receivers Cloud computing Array signal processing Downlink

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Three Dimensional Light Microscopy: Imaging &Corrections for Quantitative Analysis

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Microscopy and Microanalysis 2020年第S2期5卷 522-523页

作者： J.N. Turner W. hain D.H. Szarowski S. Lasek L. Kam A. Can K. Al-Kofahi B. Roysam Wadsworth Center New York State Department of Health The University at Albany Albany New York12201 School of Public Health The University at Albany Albany New York12201 Biomedical Engineering Rensselaer Polytechnic Institute Troy New York12180 Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy New York12180

There are several forms of three-dimensional (3-D) light microscopy but all utilize the principle of optical section recording, i.e. the 3-D image is a sequence of two-dimensional (2-D) images called optical sections. The optical sections are particular focal planes formed within the thick specimen and usually correspond to the conventional image projections recorded in a light microscope, referred to as x,y projections. The optical sections are recorded for a sequence of focus- or z-positions. This “stack” of 2-D images is the data set for the 3-D image. If quantitative analysis is to be performed on the 3-D images, the choice of the z-dimension increment between 2-D images is especially important, and its value may be more or less critical depending on the analysis algorithm used. A reasonable starting value for this dimension is the depth-of-field of the objective lens, but the actual value may have to be smaller to optimize the image analysis or larger to decrease the influence of photobleaching. The most photostable dyes should be selected and the specimen should be mounted in index-of-refraction matching media with an *** image resolution in all three-dimensions is determined by the 3-D point-spread-function (psf), and as a rough rule of thumb the z-resolution is degraded by a factor of 3 relative to the x,y resolution. To achieve or at least approach isotropic resolution the 3-D image can be deconvolved. Figure 1 shows the 2-D maximum value projection of a 3-D image of a cultured glial cell dual labeled for actin and vinculin before and after deconvolution. The actin fibers and vinculin focal contacts are more clearly resolved after deconvolution. Although a single cultured cell might traditionally be considered a thin object, it is really a thick object if the desired spatial resolution is less than the thickness of the cell. It is desirable to image as deep into a thick object as possible to maximize the tissue volume sampled. However, it has be

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Verification of AA-Diagnosability in Probabilistic Finite Automata is PSPACE-Hard

Verification of AA-Diagnosability in Probabilistic Finite Au...

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IEEE Annual Conference on Decision and Control

作者： Christoforos Keroglou Christoforos N. Hadjicostis Division of Decision and Control Systems School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden Department of Electrical and Computer Engineering University of Cyprus Nicosia Cyprus

ISBN: (数字)9781728113982

ISBN: (纸本)9781728113999

In this paper we consider the complexity of verifying the property of AA-diagnosability in probabilistic finite automata and establish that AA-diagnosability is, in general, a PSPACE-hard problem. In deterministic and nondeterministic finite automata, the property of diagnosability captures our ability to determine, based on our observation of the activity in a given finite automaton, the occurrence of any fault event, at least if we wait for at most a finite number of events (following the occurrence of the unobservable fault event). In stochastic settings where the underlying system is a probabilistic finite automaton under partial observation, there is not a prevalent notion of diagnosability and many variations have been proposed, including A-diagnosability and AA-diagnosability. Earlier work has shown that the verification of A-diagnosability (also referred to as strong stochastic diagnosability) for a given probabilistic finite automaton is a PSPACE-hard problem. In this paper, we establish that the verification of AA-diagnosability (also referred to as stochastic diagnosability) is a PSPACE-hard problem.

关键词： Automata Hidden Markov models Probabilistic logic Markov processes Complexity theory Fault diagnosis

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Reliable Distributed Computing for Metaverse: A Hierarchical Game-Theoretic Approach

arXiv

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arXiv 2021年

作者： Jiang, Yuna Kang, Jiawen Niyato, Dusit Ge, Xiaohu Xiong, Zehui Miao, Chunyan Shen, Xuemin School of Electronic Information and Communications Huazhong University of Science and Technology Hubei Wuhan430074 China Shenzhen Huazhong University Science and Technology Research Institute Guangdong Shenzhen518063 China The School of Automation Guangdong University of Technology Guangdong Guangzhou510006 China The School of Computer Science and Engineering Nanyang Technological University Singapore639798 Singapore The Pillar of Information Systems Technology and Design Singapore University of Technology and Design Singapore487372 Singapore The Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada

The metaverse is regarded as a new wave of technological transformation that provides a virtual space for people to interact through digital avatars. To achieve immersive user experiences in the metaverse, real-time rendering is the key technology. However, computing intensive tasks of real-time rendering from metaverse service providers cannot be processed efficiently on a single resource-limited mobile device. Alternatively, such mobile devices can offload the metaverse rendering tasks to other mobile devices by adopting the collaborative computing paradigm based on Coded Distributed Computing (CDC). Therefore, this paper introduces a hierarchical game-theoretic CDC framework for the metaverse services, especially for vehicular metaverse. In the framework, idle resources from vehicles, acting as CDC workers, are aggregated to handle intensive computation tasks in the vehicular metaverse. Specifically, in the upper layer, a miner coalition formation game is formulated based on a reputation metric to select reliable workers. To guarantee the reliable management of reputation values, the reputation values calculated based on the subjective logical model are maintained in a blockchain database. In the lower layer, a Stackelberg game based incentive mechanism is considered to attract reliable workers selected in the upper layer to participate in rendering tasks. The simulation results illustrate that the proposed framework is resistant to malicious workers. Compared with the best-effort worker selection scheme, the proposed scheme can improve the utility of metaverse service provider and average profit of CDC workers. Copyright © 2021, The Authors. All rights reserved.

关键词： Blockchain

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Phonon modes and Raman signatures of MnBi2nTe3n+1 (n=1,2,3,4) magnetic topological heterostructures

arXiv

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arXiv 2021年

作者： Cho, Yujin Kang, Jin Ho Liang, Liangbo Kong, Xiangru Ghosh, Subhajit Kargar, Fariborz Hu, Chaowei Balandin, Alexander A. Puretzky, Alexander A. Ni, Ni Wong, Chee Wei Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory University of California Los AngelesCA90095 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Center Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Department of Physics and Astronomy California Nano Systems Institute University of California Los AngelesCA90095 United States

An intrinsic antiferromagnetic topological insulator MnBi2Te4 can be realized by intercalating Mn-Te bilayer chain in a topological insulator, Bi2Te3. MnBi2Te4 provides not only a stable platform to demonstrate exotic physical phenomena, but also easy tunability of the physical properties. For example, inserting more Bi2Te3 layers in between two adjacent MnBi2Te4 weakens the interlayer magnetic interactions between the MnBi2Te4 layers. Here we present the first observations on the inter- and intra-layer phonon modes of MnBi2nTe3n+1 (n=1,2,3,4) using cryogenic low-frequency Raman spectroscopy. We experimentally and theoretically distinguish the Raman vibrational modes using various polarization configurations. The two peaks at 66 cm-1 and 112 cm-1 show an abnormal perturbation in the Raman linewidths below the magnetic transition temperature due to spin-phonon coupling. In MnBi4Te7, the Bi2Te3 layers induce Davydov splitting of the A1g mode around 137 cm-1 at 5 K. Using the linear chain model, we estimate the out-of-plane interlayer force constant to be (3.98 ± 0.14) × 1019 N/m3 at 5 K, three times weaker than that of Bi2Te3. Our work discovers the dynamics of phonon modes of the MnBi2Te4 and the effect of the additional Bi2Te3 layers, providing the first-principles guidance to tailor the physical properties of layered heterostructures. © 2021, CC BY-NC-ND.

关键词： Electric insulators

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Cooperative Schedule-Driven Intersection Control with Connected and Autonomous Vehicles

Cooperative Schedule-Driven Intersection Control with Connec...

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2019 IEEE/RSJ International Conference on Intelligent Robots and systems (IROS)

作者： Hsu-Chieh Hu Stephen F. Smith Rick Goldstein Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh Pennsylvania USA Robotics Institute School of Computer Science Carnegie Mellon University Pittsburgh Pennsylvania USA

Recent work in decentralized, schedule-driven traffic control has demonstrated the ability to improve the efficiency of traffic flow in complex urban road networks. In this approach, a scheduling agent is associated with each intersection. Each agent senses the traffic approaching its intersection and in real-time constructs a schedule that minimizes the cumulative wait time of vehicles approaching the intersection over the current look-ahead horizon. In this paper, we propose a cooperative algorithm that utilizes both connected and autonomous vehicles (CAV) and schedule-driven traffic control to create better traffic flow in the city. The algorithm enables an intersection scheduling agent to adjust the arrival time of an approaching platoon through use of wireless communication to control the velocity of vehicles. The sequence of approaching platoons is thus shifted toward a new shape that has smaller cumulative delay. We demonstrate how this algorithm outperforms the original approach in a real-time traffic signal control problem.

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