Broadband Enhancement of Magneto-Optical Effects in Hybrid Waveguide-Plasmonic Surfaces for Sensing.

Conventional magnetophotonic nanostructures typically function within narrow wavelength and incident angle ranges, where resonance is observed and magneto-optical (MO) effects are amplified. Expanding these operational ranges may allow for improved applications, including in (bio)sensing devices. In this study, we describe a hybrid magnetoplasmonic waveguide grating (HMPWG) in which the coupling of plasmonic resonances and waveguide modes leads to enhanced MO effects and sensitivity, according to full-wave electromagnetic simulations.

Toward Machine-Learning-Accelerated Design of All-Dielectric Magnetophotonic Nanostructures.

All-dielectric magnetophotonic nanostructures are promising for integrated nanophotonic devices with high resolution and sensitivity, but their design requires computationally demanding electromagnetic simulations evaluated through trial and error. In this paper, we propose a machine-learning approach to accelerate the design of these nanostructures. Using a data set of 12 170 samples containing four geometric parameters of the nanostructure and the incidence wavelength, trained neural network and polynomial regression algorithms were capable of predicting the amplitude of the transverse magneto-optical Kerr effect (TMOKE) within a time frame of 10 s and mean square error below 4.

ANN-Based LiDAR Positioning System for B5G.

This work reports the development of an efficient and precise indoor positioning system utilizing two-dimensional (2D) light detection and ranging (LiDAR) technology, aiming to address the challenging sensing and positioning requirements of the beyond fifth-generation (B5G) mobile networks. The core of this work is the implementation of a 2D-LiDAR system enhanced by an artificial neural network (ANN), chosen due to its robustness against electromagnetic interference and higher accuracy over traditional radiofrequency signal-based methods. The proposed system uses 2D-LiDAR sensors for data acquisition and digital filters for signal improvement.

Magnetochiroptical nanocavities in hyperbolic metamaterials enable sensing down to the few-molecule level.

In this work, we combine the concepts of magnetic circular dichroism, nanocavities, and magneto-optical hyperbolic metamaterials (MO-HMMs) to demonstrate an approach for sensing down to a few molecules. Our proposal comprises a multilayer MO-HMM with a square, two-dimensional arrangement of nanocavities. The magnetization of the system is considered in polar configuration, i.

A Survey on the Impact of Intelligent Surfaces in the Terahertz Communication Channel Models.

Terahertz (THz) band will play an important role in enabling sixth generation (6G) envisioned applications. Compared with lower frequency signals, THz waves are severely attenuated by the atmosphere temperature, pressure, and humidity. Thus, designing a THz communication system must take into account how to circumvent or diminish those issues to achieve a sufficient quality of service.

New Horizons in Near-Zero Refractive Index Photonics and Hyperbolic Metamaterials.

The engineering of the spatial and temporal properties of both the electric permittivity and the refractive index of materials is at the core of photonics. When vanishing to zero, those two variables provide efficient knobs to control light-matter interactions. This Perspective aims at providing an overview of the state of the art and the challenges in emerging research areas where the use of near-zero refractive index and hyperbolic metamaterials is pivotal, in particular, light and thermal emission, nonlinear optics, sensing applications, and time-varying photonics.

Simultaneous Estimation of Azimuth and Elevation Angles Using a Decision Tree-Based Method.

This study addresses the problem of accurately predicting azimuth and elevation angles of signals impinging on an antenna array employing Machine Learning (ML). Using the information obtained at a receiving system when a transmitter's signal hits it, a Decision Tree (DT) model is trained to estimate azimuth and elevation angles simultaneously. Simulation results demonstrate the robustness of the proposed DT-based method, showcasing its ability to predict the Direction of Arrival (DOA) in diverse conditions beyond the ones present in the training dataset, i.

Modified Gini Index Detector for Cooperative Spectrum Sensing over Line-of-Sight Channels.

Recently, the Gini index detector (GID) has been proposed as an alternative for data-fusion cooperative spectrum sensing, being mostly suitable for channels with line-of-sight or dominant multi-path components. The GID is quite robust against time-varying noise and signal powers, has the constant false-alarm rate property, can outperform many the state-of-the-art robust detectors, and is one of the simplest detectors developed so far. The modified GID (mGID) is devised in this article.

A Literature Survey on AI-Aided Beamforming and Beam Management for 5G and 6G Systems.

Modern wireless communication systems rely heavily on multiple antennas and their corresponding signal processing to achieve optimal performance. As 5G and 6G networks emerge, beamforming and beam management become increasingly complex due to factors such as user mobility, a higher number of antennas, and the adoption of elevated frequencies. Artificial intelligence, specifically machine learning, offers a valuable solution to mitigate this complexity and minimize the overhead associated with beam management and selection, all while maintaining system performance.

Enabling Semantic-Functional Communications for Multiuser Event Transmissions via Wireless Power Transfer.

A central concern for large-scale sensor networks and the Internet of Things (IoT) has been battery capacity and how to recharge it. Recent advances have pointed to a technique capable of collecting energy from radio frequency (RF) waves called radio frequency-based energy harvesting (RF-EH) as a solution for low-power networks where cables or even changing the battery is unfeasible. The technical literature addresses energy harvesting techniques as an isolated block by dealing with energy harvesting apart from the other aspects inherent to the transmitter and receiver.

Magnetoplasmonic Nanoantennas for On-Chip Reconfigurable Optical Wireless Communications.

On-chip wireless communications require optical nanoantennas with dynamically tunable radiation patterns, which may allow for higher integration with multiple nanoantennas instead of two fixed nanoantennas in existing approaches. In this paper, we introduce a concept to enable active manipulation of radiated beam steering using applied magnetic fields. The proposed system consists of a highly directive Yagi-Uda-like arrangement of magnetoplasmonic nanoribs made of CoAg and immersed in SiO.

Magnetically Tunable Micro-Ring Resonators for Massive Magneto-Optical Modulation in Dense Wavelength Division Multiplexing Systems.

We demonstrate, numerically, a new concept for on-chip magneto-optical (MO) modulation in dense wavelength division multiplexing (DWDM) applications. Our idea uses materials and mechanisms that are compatible with current silicon-on-insulator fabrication and CMOS technologies for monolithic integration. The physics behind our idea stems in the exploitation of the enhanced MO activity of a micro-ring, made of cerium substituted yttrium iron garnet (Ce:YIG) material, to actively manipulate the resonance wavelengths of an adjacent micro-ring resonator (MRR) of silicon (Si).

Design of Plasmonic Yagi-Uda Nanoantennas for Chip-Scale Optical Wireless Communications.

Optical wireless transmission has recently become a major cutting-edge alternative for on-chip/inter-chip communications with higher transmission speeds and improved power efficiency. Plasmonic nanoantennas, the building blocks of this new nanoscale communication paradigm, require precise design to have directional radiation and improved communication ranges. Particular interest has been paid to plasmonic Yagi-Uda, i.

All-dielectric magnetophotonic gratings for maximum TMOKE enhancement.

All-dielectric nanophotonic devices are promising candidates for future lossless (bio)sensing and telecommunication applications. Active all-dielectric magnetophotonic devices, where the optical properties can be controlled by an externally applied magnetic field, have triggered great research interest. However, magneto-optical (MO) effects are still low for applications.

Optically-Powered Wireless Sensor Nodes towards Industrial Internet of Things.

We report the experimental implementation of optically-powered wireless sensor nodes based on the power-over-fiber (PoF) technology, aiming at Industrial Internet of Things (IIoT) applications. This technique employs optical fibers to transmit power and is proposed as a solution to address the hazardous industrial environment challenges, e.g.

3D-Printed Quasi-Cylindrical Bragg Reflector to Boost the Gain and Directivity of cm- and mm-Wave Antennas.

We demonstrate a concept for a large enhancement of the directivity and gain of readily available cm- and mm-wave antennas, i.e., without altering any property of the antenna design.

Design of Nanoarchitectures for Magnetoplasmonic Biosensing with Near-Zero-Transmittance Conditions.

Nanostructures exhibiting large transverse magneto-optical Kerr effect (TMOKE) are required for magnetoplasmonic biosensing if the aim is the minituarization and integration into microfluidic devices. In this work, we present a general strategy to design nanoarchitectures with enhanced TMOKE, which consist of an arrangement of gold ribs deposited on an magneto-optical (MO) dielectric slab of Bi:YIG (bismuth-substituted yttrium iron garnet) with a SiO substrate surrounded by water. Using the finite element method (FEM), we demonstrate numerically that the near-zero-transmittance condition is the most important requirement for high TMOKE values.

Performance Analysis of the IEEE 802.15.4 Protocol for Smart Environments under Jamming Attacks.

Jamming attacks in wireless sensor networks (WSNs) scenarios are detrimental to the performance of these networks and affect the security and stability of the service perceived by users. Therefore, the evaluation of the effectiveness of smart environment platforms based on WSNs has to consider the system performance when data collection is executed under jamming attacks. In this work, we propose an experimental testbed to analyze the performance of a WSN using the IEEE 802.

Design Guidelines for Database-Driven Internet of Things-Enabled Dynamic Spectrum Access.

The radio-frequency spectrum shortage, which is primarily caused by the fixed allocation policy, is one of the main bottlenecks to the deployment of existing wireless communication networks, and to the development of new ones. The dynamic spectrum access policy is foreseen as the solution to this problem, since it allows shared spectrum usage by primary licensed and secondary unlicensed networks. In order to turn this policy into reality, the secondary network must be capable of acquiring reliable, real-time information on available bands within the service area, which can be achieved by means of spectrum sensing, spectrum occupancy databases, or a combination of them.

Chiral Dielectric Metasurfaces for Highly Integrated, Broadband Circularly Polarized Antenna.

We report on the design of a low-profile integrated millimeter-wave antenna for efficient and broadband circularly polarized electromagnetic radiation. The designed antenna comprises a chiral dielectric metasurface built with a 2×2 arrangement of dielectric cylinders with slanted-slots at the center. A broadbeam high-gain with wide axial ratio (AR)<3 dB bandwidth was reached by pairing the electric and magnetic resonances of the dielectric cylinders and the slanted slots when excited by an elliptically polarized driven-patch antenna.

Surface Plasmon Resonances in Sierpinski-Like Photonic Crystal Fibers: Polarization Filters and Sensing Applications.

We investigate the plasmonic behavior of a fractal photonic crystal fiber, with Sierpinski-like circular cross-section, and its potential applications for refractive index sensing and multiband polarization filters. Numerical results were obtained using the finite element method through the commercial software COMSOL Multiphysics. A set of 34 surface plasmon resonances was identified in the wavelength range from λ=630 nm to λ=1700 nm.

Refractive index of ZnO ultrathin films alternated with AlO in multilayer heterostructures.

The design of optoelectronic devices made with ZnO superlattices requires the knowledge of the refractive index, which currently can be done only for films thicker than 30 nm. In this work, we present an effective medium approach to determine the refractive index of ZnO layers as thin as 2 nm. The approach was implemented by determining the refractive index of ZnO layers ranging from 2 nm to 20 nm using spectroscopic ellipsometry measurements in multilayers.

Random-Access Accelerator (RAA): A Framework to Speed Up the Random-Access Procedure in 5G New Radio for IoT mMTC by Enabling Device-To-Device Communications.

Mobile networks have a great challenge by serving the expected billions of (IoT) devices in the upcoming years. Due to the limited simultaneous access in the mobile networks, the devices should compete between each other for resource allocation during a procedure. This contention provokes a non-depreciable delay during the device's registration because of the great number of collisions experienced.

Cooperative Full-Duplex V2V-VLC in Rectilinear and Curved Roadway Scenarios.

We study here the vehicle-to-vehicle (V2V) visible light communication (VLC) between two cars moving along different roadway scenarios: (i) a multiple-lane rectilinear roadway and (ii) a multiple-lane curvilinear roadway. Special emphasis was given to the implementation of full-duplex (FD) cooperative communication protocols to avoid communication disruption in the absence of a line-of-sight (LOS) channel. Importantly, we found that the cooperative FD V2V-VLC is promising for avoiding communication disruptions for cars traveling in realistic curvilinear roadways.

Plasmonics for Telecommunications Applications.

Plasmonic materials, when properly illuminated with visible or near-infrared wavelengths, exhibit unique and interesting features that can be exploited for tailoring and tuning the light radiation and propagation properties at nanoscale dimensions. A variety of plasmonic heterostructures have been demonstrated for optical-signal filtering, transmission, detection, transportation, and modulation. In this review, state-of-the-art plasmonic structures used for telecommunications applications are summarized.