Wide-angle absorption of visible light from simple bilayers

Color-selective absorption of light is a very significant operation used in numerous applications, from photonic sensing and switching to optical signal modulation and energy harnessing. We demonstrate angle-insensitive and polarization-independent absorption by thin bilayers comprising ordinary bulk media: dielectrics, semiconductors, and metals. Several highly efficient designs for each color of the visible spectrum are reported, and their internal fields’ distributions reveal the resonance mechanism of absorption. The proposed bilayer components are realizable, since various physical or chemical deposition methods can be used for their effective fabrication. The absorption process is found to exhibit endurance with respect to the longitudinal dimension of the planar structure, which means that the same designs could be successfully utilized in non-planar configurations composed of arbitrary shapes

A spectrally-accurate FVTD technique for complicated amplification and reconfigurable filtering EMC devices

The consistent and computationally economical analysis of demanding amplification and filtering structures is introduced in this paper via a new spectrally-precise finite-volume time-domain algorithm. Combining a family of spatial derivative approximators with controllable accuracy in general curvilinear coordinates, the proposed method employs a fully conservative field flux formulation to derive electromagnetic quantities in areas with fine structural details. Moreover, the resulting 3-D operators assign the appropriate weight to each spatial stencil at arbitrary media interfaces, while for periodic components the domain is systematically divided to a number of nonoverlapping subdomains. Numerical results from various real-world configurations verify our technique and reveal its universality

Enhanced Design of Narrowband Filters Based on The Extraordinary Transmission Through Single Fishnet Structures

A systematic method for the efficient design of narrowband filters founded on the extraordinary transmission via single fishnet structures (SFSs) is presented in this paper. Essentially, due to its strong resonant behavior, this phenomenon is proven suitable for the implementation of high-Q devices. The new design formulas are derived through the combination of full-wave numerical simulations and curve fitting algorithms. Also, adequate mathematical criteria are defined for the evaluation of the filters\u27 linear performance, indicating that the transmitted electromagnetic waves remain practically undistorted in the frequency band of interest. Then, by exploiting the previously developed relations, proper correction factors are introduced in the existing SFS equivalent circuit expressions, which hardly increase the overall computational complexity. This quantitative modification leads to an enhanced characterization of SFSs, as key components for diverse applications. Finally, several limitations as well as possible ways of extending the featured algorithm to more complicated structures and higher frequency bands are briefly discussed

Intelligent Metasurfaces with Continuously Tunable Local Surface Impedance for Multiple Reconfigurable Functions

Electromagnetic metasurfaces can be characterized as intelligent if they are able to perform multiple tunable functions, with the desired response being controlled by a computer influencing the individual electromagnetic properties of each metasurface inclusion. In this paper, we present an example of an intelligent metasurface which operates in the reflection mode in the microwave frequency range. We numerically show that without changing the main body of the metasurface we can achieve tunable perfect absorption and tunable anomalous reflection. The tunability features can be implemented using mixed-signal integrated circuits (ICs), which can independently vary both the resistance and reactance, offering complete local control over the complex surface impedance. The ICs are embedded in the unit cells by connecting two metal patches over a thin grounded substrate and the reflection property of the intelligent metasurface can be readily controlled by a computer. Our intelligent metasurface can have significant influence on future space-time modulated metasurfaces and a multitude of applications, such as beam steering, energy harvesting, and communications.Comment: 10 pages, 8 figure

Ultralow-Loss Reconfigurable Phase-Shifting Metasurface in V Band:A Multiobjective Optimization Approach

Future generations of satellite and mobile communications at mm-wave frequencies require the use of low-loss and wideband phase-shifting components. Pixelated metasurfaces provide large design versatility and constitute an attractive solution for wave manipulation, such as shifting the phase of an incident wave. However, their design often implies the simultaneous tuning of a large number of geometrical parameters. This article employs an enhanced multiobjective optimization algorithm to design a dynamically reconfigurable metasurface providing ultralow losses and linear phase response. The presented methodology can be easily employed for different objective functions or technologies, constituting a versatile design strategy for electromechanically reconfigurable devices based on pixelated metasurfaces. A prototype is fabricated based on the optimization outcome, achieving a phase shifter capable of providing a continuous phase shift up to 180° between 50 and 65 GHz. A piezo-electric actuator is used to dynamically adjust the phase shift with respect to the position of a metallic ground plane placed in front of the metasurface. A linear evolution of the phase w.r.t. the ground plane displacement is obtained while maintaining the losses around 1 dB for the whole frequency range

Tunable graphene-based metasurfaces for multi-wideband 6G communications

The next generation of wireless communications within the framework of 6G will be operational at the low THz frequency band. Although THz systems will dramatically enhance several performance indicators such as the data rate, spectral efficiency, and latency, exploiting such technology is challenging. Electromagnetic waves confront severe propagation losses including atmospheric attenuation and diffraction. Thus, such communications are limited to line-of-sight scenarios. In 5G networks, Reconfigurable Intelligent Surfaces (RISs) are intro-duced to solve this issue by redirecting the incident wave toward the receiver and implement virtual-line-of-sight communications. In this paper, we aim to employ this paradigm for 6G networks and design a graphene-based RIS optimized to perform at multiple low atmospheric attenuation channels. We investigate the performance of this multi-wideband design through numerical and analytical analysis.Peer ReviewedPostprint (author's final draft

Exploration of intercell wireless millimeter-wave communication in the landscape of intelligent metasurfaces

Software-defined metasurfaces are electromagnetically ultra-thin, artificial components thatcan provide engineered and externally controllable functionalities. The control over these functionalities isenabled by the metasurface tunability, which is implemented by embedded electronic circuits that modifylocally the surface resistance and reactance. Integrating controllers within the metasurface able them tointercommunicate and adaptively reconfigure, thus imparting a desired electromagnetic operation, opens thepath towards the creation of an artificially intelligent (AI) fabric where each unit cell can have its own sensing,programmable computing, and actuation facilities. In this work we take a crucial step towards bringing theAI metasurface technology to emerging applications, in particular exploring the wireless mm-wave intercellcommunication capabilities in a software-defined HyperSurface designed for operation in the microwaveregime. We examine three different wireless communication channels within the landscape of the reflectivemetasurface: Firstly, in the layer where the control electronics of the HyperSurface lie, secondly inside adedicated layer enclosed between two metallic plates, and, thirdly, inside the metasurface itself. For each casewe examine the physical implementation of the mm-wave transceiver nodes, we quantify communicationchannel metrics, and we identify complexity vs. performance trade-offs.Peer ReviewedPostprint (published version

МОДУЛЬНЕ ФУНКЦІОНУВАННЯ АРХІТЕКТУРИ ІНФОРМАЦІЙНОЇ МЕДИЧНОЇ СИСТЕМИ ОХОРОНИ ЗДОРОВ'Я УКРАЇНИ

The article deals with the perspective direction of analysis of the modular functioning of the information medical system. An example of a basic approach in identifying internal mechanisms for streamlining the multilevel information structure is the Ukrainian medical system, known as «EMSIMED». The approach to finding a clear modular playback algorithm allows to reasonably disclosing the process of automated integration at the scientific and technological level.В статье рассматривается перспективное направление анализа модульного функционирования информационной медицинской системы. Примером выведения базового пути при определении внутренних механизмов упорядочивания многоуровневой информационной структуры является украинская медицинская система «ЭМСИМЕД». Подход к поиску чёткого алгоритма модульного отображения позволяет аргументировано раскрыть процесс автоматизированной интеграции на научно-технологическом уровне.У статті розглядається перспективний напрям аналізу модульного функціонування інформаційної медичної системи. Прикладом формування базового шляху при визначенні внутрішніх механізмів упорядкування багаторівневої інформаційної структури є українська медична система «ЕМСІМЕД». Підхід до пошуку чіткого алгоритму модульного відтворення дозволяє обґрунтовано розкрити процес автоматизованої інтеграції на науково-технологічному рівні