131 research outputs found

    Fast Terahertz Metamaterial/Graphene-Based Optoelectronic Devices for Wireless Communication

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    Research in the terahertz (THz) band, which is broadly defined as 0.1-10 THz, is an active area of research driven by applications in sixth generation (6G) and beyond for communications, spectroscopy, imaging, and sensing. In order to exploit the full potential of all these applications, fast integrated circuitry is required. This work revolves around removing this bottleneck. Achievement of efficient dynamic modulation requires the implementation of active material. Amongst many different approaches to achieve active modulation, metamaterials/graphene-based technology is establishing itself as a benchmark for THz operation due to its versatility, power efficiency, small footprint, and integration capabilities. Our devices have been modulated all-electronically, as described in Chapters 4 and 6, and all-optically as reported in Chapter 5. The fabrication of the novel design based on metamaterial (MM) and graphene for amplitude, phase, and polarization modulations is reported in Chapter 3. The optoelectronic behaviour of this modulator is tested in a THz time-domain spectroscopy (THz-TDS) setup as demonstrated in Chapter 4. By choosing the appropriate THz-TDS setup configuration, a spectral amplitude extinction ratio of >10 dB (>93%) at the resonant frequency of 0.8 THz is demonstrated. The spectral phase of THz radiations is actively tuned by >27o at 0.62 THz frequency. Linear to circular polarization conversion with nearly 100% of conversion efficiency is reported demonstrating almost an independent control of circular dichroism (CD) and optical activity (OA) as mentioned explicitly in Chapter 6. Dynamic changes of ellipticity are reported to exceed 0.3 in ratio at resonance. The OA of transmitted THz radiations is continuously rotated by >21.5o at 0.71 THz by varying the gate. These values are in line with acquainted literature with graphene-based or 2-dimensional electron gas modulators but with higher reconfiguration speed. The helicity, either right or left circular polarization states, of elliptical waves can be controlled. These results are of great importance for fundamental research of polarization spectroscopy, polarization imaging, or THz applications in the pharmaceutical and biomedical fields. An all-electronic controlled metamaterial-based THz modulator is demonstrated to achieve a recorded operating speed >3 GHz which is limited by the available instrumentation as illustrated in Section 7.1. The achievements in the modulation speed (in GHz range), amplitude extinction ratio (>10 dB), phase shift tuning (27o), and nearly decoupled control of OA and CD of THz waves are the key values of this device, which is undoubtedly meaningful for communication applications and has a certain impact on the THz modulator technology. The achieved GHz modulation speed of this hybrid MMs/graphene device is within very good agreement with previous literature reported on pristine graphene. This result provides an upper intrinsic limit of the maximum reconfiguration speed of these devices to 100s of GHz and, at the same time, reinforces the use of metamaterial/graphene optoelectronic devices for ultrafast modulation of terahertz waves. This overall remarkable performance of an optoelectronic modulator based on metamaterial/graphene resonators is capable of efficiently modulating THz radiation all-electronically with GHz-reconfiguration speed. It is worth highlighting that this exceptionally high reconfiguration speed, the highest reported so far to the best of our knowledge for a graphene-based integrated device, was not achieved at the expense of the other performances, e.g. amplitude and polarization modulation depths. These results represent great progress for several terahertz research and ultrafast photonic applications, such as the realization of fast deep, and efficient THz circuitry for the investigation of exotic quantum phenomena, wireless communications, and laser diodes stabilization in quantum electronics

    2023 Astrophotonics Roadmap: pathways to realizing multi-functional integrated astrophotonic instruments

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    This is the final version. Available on open access from IOP Publishing via the DOI in this recordData availability statement: The data that support the findings of this study are available upon reasonable request from the authors.Photonic technologies offer numerous functionalities that can be used to realize astrophotonic instruments. The most spectacular example to date is the ESO Gravity instrument at the Very Large Telescope in Chile that combines the light-gathering power of four 8 m telescopes through a complex photonic interferometer. Fully integrated astrophotonic devices stand to offer critical advantages for instrument development, including extreme miniaturization when operating at the diffraction-limit, as well as integration, superior thermal and mechanical stabilization owing to the small footprint, and high replicability offering significant cost savings. Numerous astrophotonic technologies have been developed to address shortcomings of conventional instruments to date, including for example the development of photonic lanterns to convert from multimode inputs to single mode outputs, complex aperiodic fiber Bragg gratings to filter OH emission from the atmosphere, complex beam combiners to enable long baseline interferometry with for example, ESO Gravity, and laser frequency combs for high precision spectral calibration of spectrometers. Despite these successes, the facility implementation of photonic solutions in astronomical instrumentation is currently limited because of (1) low throughputs from coupling to fibers, coupling fibers to chips, propagation and bend losses, device losses, etc, (2) difficulties with scaling to large channel count devices needed for large bandwidths and high resolutions, and (3) efficient integration of photonics with detectors, to name a few. In this roadmap, we identify 24 key areas that need further development. We outline the challenges and advances needed across those areas covering design tools, simulation capabilities, fabrication processes, the need for entirely new components, integration and hybridization and the characterization of devices. To realize these advances the astrophotonics community will have to work cooperatively with industrial partners who have more advanced manufacturing capabilities. With the advances described herein, multi-functional integrated instruments will be realized leading to novel observing capabilities for both ground and space based platforms, enabling new scientific studies and discoveries.National Science Foundation (NSF)NAS

    Review of Particle Physics

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    The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume 2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app.United States Department of Energy (DOE) DE-AC02-05CH11231government of Japan (Ministry of Education, Culture, Sports, Science and Technology)Istituto Nazionale di Fisica Nucleare (INFN)Physical Society of Japan (JPS)European Laboratory for Particle Physics (CERN)United States Department of Energy (DOE

    Understanding Quantum Technologies 2022

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    Understanding Quantum Technologies 2022 is a creative-commons ebook that provides a unique 360 degrees overview of quantum technologies from science and technology to geopolitical and societal issues. It covers quantum physics history, quantum physics 101, gate-based quantum computing, quantum computing engineering (including quantum error corrections and quantum computing energetics), quantum computing hardware (all qubit types, including quantum annealing and quantum simulation paradigms, history, science, research, implementation and vendors), quantum enabling technologies (cryogenics, control electronics, photonics, components fabs, raw materials), quantum computing algorithms, software development tools and use cases, unconventional computing (potential alternatives to quantum and classical computing), quantum telecommunications and cryptography, quantum sensing, quantum technologies around the world, quantum technologies societal impact and even quantum fake sciences. The main audience are computer science engineers, developers and IT specialists as well as quantum scientists and students who want to acquire a global view of how quantum technologies work, and particularly quantum computing. This version is an extensive update to the 2021 edition published in October 2021.Comment: 1132 pages, 920 figures, Letter forma

    Optical coherence tomography methods using 2-D detector arrays

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    Optical coherence tomography (OCT) is a non-invasive, non-contact optical technique that allows cross-section imaging of biological tissues with high spatial resolution, high sensitivity and high dynamic range. Standard OCT uses a focused beam to illuminate a point on the target and detects the signal using a single photodetector. To acquire transverse information, transversal scanning of the illumination point is required. Alternatively, multiple OCT channels can be operated in parallel simultaneously; parallel OCT signals are recorded by a two-dimensional (2D) detector array. This approach is known as Parallel-detection OCT. In this thesis, methods, experiments and results using three parallel OCT techniques, including full -field (time-domain) OCT (FF-OCT), full-field swept-source OCT (FF-SS-OCT) and line-field Fourier-domain OCT (LF-FD-OCT), are presented. Several 2D digital cameras of different formats have been used and evaluated in the experiments of different methods. With the LF-FD-OCT method, photography equipment, such as flashtubes and commercial DSLR cameras have been equipped and tested for OCT imaging. The techniques used in FF-OCT and FF-SS-OCT are employed in a novel wavefront sensing technique, which combines OCT methods with a Shack-Hartmann wavefront sensor (SH-WFS). This combination technique is demonstrated capable of measuring depth-resolved wavefront aberrations, which has the potential to extend the applications of SH-WFS in wavefront-guided biomedical imaging techniques

    Smart-antenna techniques for energy-efficient wireless sensor networks used in bridge structural health monitoring

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    Abstract: It is well known that wireless sensor networks differ from other computing platforms in that 1- they typically require a minimal amount of computing power at the nodes; 2- it is often desirable for sensor nodes to have drastically low power consumption. The main benefit of the this work is a substantial network life before batteries need to be replaced or, alternatively, the capacity to function off of modest environmental energy sources (energy harvesting). In the context of Structural Health Monitoring (SHM), battery replacement is particularly problematic since nodes can be in difficult to access locations. Furthermore, any intervention on a bridge may disrupt normal bridge operation, e.g. traffic may need to be halted. In this regard, switchbeam smart antennas in combination with wireless sensor networks (WSNs) have shown great potential in reducing implementation and maintenance costs of SHM systems. The main goal of implementing switch-beam smart antennas in our application is to reduce power consumption, by focusing the radiated energy only where it is needed. SHM systems capture the dynamic vibration information of a bridge structure in real-time in order to assess the health of the structure and to predict failures. Current SHM systems are based on piezoelectric patch sensors. In addition, the collection of data from the plurality of sensors distributed over the span of the bridge is typically performed through an expensive and bulky set of shielded wires which routes the information to a data sink at one end of the structure. The installation, maintenance and operational costs of such systems are extremely high due to high power consumption and the need for periodic maintenance. Wireless sensor networks represent an attractive alternative, in terms of cost, ease of maintenance, and power consumption. However, network lifetime in terms of node battery life must be very long (ideally 5–10 years) given the cost and hassle of manual intervention. In this context, the focus of this project is to reduce the global power consumption of the SHM system by implementing switched-beam smart antennas jointly with an optimized MAC layer. In the first part of the thesis, a sensor network platform for bridge SHM incorporating switched-beam antennas is modelled and simulated. where the main consideration is the joint optimization of beamforming parameters, MAC layer, and energy consumption. The simulation model, built within the Omnet++ network simulation framework, incorporates the energy consumption profiles of actual selected components (microcontroller, radio interface chip). The energy consumption and packet delivery ratio (PDR) of the network with switched-beam antennas is compared with an equivalent network based on omnidirectional antennas. In the second part of the thesis, this system model is leveraged to examine two distinct but interrelated aspects: Gallium Arsenide (GaAs) based solar energy harvesting and switched-beam antenna strategies. The main consideration here is the joint optimization of solar energy harvesting and switchedbeam directional antennas, where an equivalent network based on omnidirectional antennas acts as a baseline reference for comparison purposes.Il est bien connu que les rĂ©seaux de capteurs sans fils diffĂšrent des autres plateformes informatiques Ă©tant donnĂ© 1- qu’ils requiĂšrent typiquement une puissance de calcul minimale aux noeuds du rĂ©seau ; 2- qu’il est souvent dĂ©sirable que les noeuds capteurs aient une consommation d’énergie dramatiquement faible. La principale retombĂ©e de ce travail rĂ©side en la durĂ©e de vie allongĂ©e du rĂ©seau avant que les piles ne doivent ĂȘtre remplacĂ©es ou, alternativement, la capacitĂ© de fonctionner indĂ©finiment Ă  partir de modestes sources d’énergie ambiente (glĂąnage d’énergie). Dans le contexte du contrĂŽle de la santĂ© structurale (CSS), le remplacement de piles est particuliĂšrement problĂ©matique puisque les noeuds peuvent se trouver en des endroits difficiles d’accĂšs. De plus, toute intervention sur un pont implique une perturbation de l’opĂ©ration normale de la structure, par exemple un arrĂȘt du traffic. Dans ce contexte, les antennes intelligentes Ă  commutation de faisceau en combinaison avec les rĂ©seaux de capteurs sans fils ont dĂ©montrĂ© un grand potentiel pour rĂ©duire les coĂ»ts de rĂ©alisation et d’entretien de systĂšmes de CSS. L’objectif principal de l’intĂ©gration d’antennes Ă  commutation de faisceau dans notre application rĂ©side dans la rĂ©duction de la consommation Ă©nergĂ©tique, rĂ©alisĂ©e en concentrant l’énergie radiĂ©e uniquement lĂ  oĂč elle est nĂ©cessaire. Les systĂšmes de CSS capturent l’information dynamique de vibration d’une structure de pont en temps rĂ©el de maniĂšre Ă  Ă©valuer la santĂ© de la structure et prĂ©dire les failles. Les systĂšmes courants de CSS sont basĂ©s sur des senseurs piĂ©zoĂ©lectriques planaires. De plus, la collecte de donnĂ©es Ă  partir de la pluralitĂ© de senseurs distribuĂ©s sur l’étendue du pont est typiquement effectuĂ©e par le biais d’un ensemble coĂ»teux et encombrant de cĂąbles blindĂ©s qui vĂ©hiculent l’information jusqu’à un point de collecte Ă  une extremitĂ© de la structure. L’installation, l’entretien, et les coĂ»ts opĂ©rationnels de tels systĂšmes sont extrĂȘmement Ă©levĂ©s Ă©tant donnĂ© la consommation de puissance Ă©levĂ©e et le besoin d’entretien rĂ©gulier. Les rĂ©seaux de capteurs sans fils reprĂ©sentent une alternative attrayante, en termes de coĂ»t, facilitĂ© d’entretien et consommation Ă©nergĂ©tique. Toutefois, la vie de rĂ©seau en termes de la durĂ©e de vie des piles doit ĂȘtre trĂšs longue (idĂ©alement de 5 Ă  10 ans) Ă©tant donnĂ© le coĂ»t et les problĂšmes liĂ©s Ă  l’intervention manuelle. Dans ce contexte, ce projet se concentre sur la rĂ©duction de la consommation de puissance globale d’un systĂšme de CSS en y intĂ©grant des antennes intelligentes Ă  commutation de faisceau conjointement avec une couche d’accĂšs au mĂ©dium (couche MAC) optimisĂ©e. Dans la premiĂšre partie de la thĂšse, une plateforme de rĂ©seau de capteurs sans fils pour le CSS d’un pont incorporant des antennes Ă  commutation de faisceaux est modĂ©lisĂ© et simulĂ©, avec pour considĂ©ration principale l’optimisation des paramĂštres de sĂ©lection de faisceau, de la couche MAC et de la consommation d’énergie. Le modĂšle de simulation, construit dans le logiciel de simulation de rĂ©seaux Omnet++, incorpore les profils de consommation d’énergie de composants rĂ©els sĂ©lectionnĂ©s (microcontrĂŽleur, puce d’interface radio). La consommation d’énergie et le taux de livraison de paquets du rĂ©seau avec antennes Ă  commutation de faisceau est comparĂ© avec un rĂ©seau Ă©quivalent basĂ© sur des antennes omnidirectionnelles. Dans la deuxiĂšme partie de la thĂšse, le modĂšle systĂšme proposĂ© est mis Ă  contribution pour examiner deux aspects distrincts mais interreliĂ©s : le glĂąnage d’énergie Ă  partir de cellules solaire Ă  base d’arsĂ©niure de Gallium (GaAs) et les stratĂ©gies liĂ©es aux antennes Ă  commutation de faisceau. La considĂ©ration principale ici est l’optimisation conjointe du glĂąnage d’énergie et des antennes Ă  commutation de faisceau, en ayant pour base de comparaison un rĂ©seau Ă©quivalent Ă  base d’antennes omnidirectionnelles

    Sensors for Vital Signs Monitoring

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    Sensor technology for monitoring vital signs is an important topic for various service applications, such as entertainment and personalization platforms and Internet of Things (IoT) systems, as well as traditional medical purposes, such as disease indication judgments and predictions. Vital signs for monitoring include respiration and heart rates, body temperature, blood pressure, oxygen saturation, electrocardiogram, blood glucose concentration, brain waves, etc. Gait and walking length can also be regarded as vital signs because they can indirectly indicate human activity and status. Sensing technologies include contact sensors such as electrocardiogram (ECG), electroencephalogram (EEG), photoplethysmogram (PPG), non-contact sensors such as ballistocardiography (BCG), and invasive/non-invasive sensors for diagnoses of variations in blood characteristics or body fluids. Radar, vision, and infrared sensors can also be useful technologies for detecting vital signs from the movement of humans or organs. Signal processing, extraction, and analysis techniques are important in industrial applications along with hardware implementation techniques. Battery management and wireless power transmission technologies, the design and optimization of low-power circuits, and systems for continuous monitoring and data collection/transmission should also be considered with sensor technologies. In addition, machine-learning-based diagnostic technology can be used for extracting meaningful information from continuous monitoring data

    Microwave Photonic Sensing Based on Optical Microresonators

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    Optical microresonators (OMRs) have been widely applied in various sensing applications. However, the sensing performances of conventional OMR-based sensors are subject to resonance parameters and fabrication accuracy and are further restricted by the interrogation scheme used. Recently, microwave photonic (MWP) techniques have been used to realize high-speed and high-resolution OMR-based sensors. So far, those MWP schemes are either still fabrication dependent or only applicable to specific uses, and rare attention has been paid to achieving multi-parameter sensing that is indispensable in real-life applications. The thesis proposes novel OMR-based MWP sensing schemes with improved sensing performances. Based on the MWP sideband processing technique, a new MWP interrogation scheme, which features a high resolution regardless of the OMR parameters and fabrication imperfections, is proposed and demonstrated in the sensing of temperature, humidity, and magnetic field, respectively, with high sensitivity and high resolution, where an automatic correction mechanism is added to compensate for resonance lineshape variation automatically. Next, the high-resolution MWP sensing scheme is extended to cascaded OMRs to enable multi-parameter sensing capability. The simultaneous high-resolution MWP sensing of temperature and humidity with two cascaded OMRs is demonstrated. Lastly, machine learning (ML) and deep learning (DL) techniques are applied to MWP sensing to reduce the complexity further. The temperature-insensitive MWP humidity sensor is first achieved with the support vector regression. Then, a new MWP multi-parameter sensing paradigm with the least requirement on the OMR structure is proposed by incorporating DL to process the raw interrogation results directly. The simultaneous MWP sensing of temperature and humidity with a single optical resonance using the convolutional neural tangent kernel is demonstrated

    Review of Particle Physics

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    The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume 2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app
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