Electromagnetic Waves Research Articles

Higher Harmonic Generation Arising from the Bessel Function Expansions of the Carrier-Envelope-Phase Driven by the Femtosecond Optical Kerr Effect

This paper expands upon previous reports based on the EM Kerr model-based HHG simulation from the carrier-envelope phase (CEP) of the electromagnetic laser light wave based on electronic self-phase modulation (ESPM) from the optical Kerr index. The underpinning mechanism described for generating HHG arises from the CEP of the nonlinear index of refraction, which yields a series of Bessel functions. The envelope of the electric field E(t) of the intense ultrashort light pulses drives the CEP, resulting in many Bessel functions, one of the salient features of HHG. The HHG from the large number of Bessel function modes can produce attosecond pulses and possibly can even produce zeptosecond pulses by Kerr mode-locking among the large number N of Bessel functions.

Electromagnetic wave propagation through one-dimensional plasma photonic crystals based on the Galois sequences

Electromagnetic wave propagation through one-dimensional plasma photonic crystals based on the Galois sequences

Quantum food and nutrition: Subatomic approaches to nourishment for health and well-being.

Nutrition science has been represented as biomedical, environmental, societal and economic field, but quantum biology is sidestepped, thereby obscuring cognate problems and solutions. We are generally nourished for health, optimal well-being, longevity and personal security through sustainable livelihoods. Our nourish-ments include not only food and energy but also light from the sun, the firmament and the earth itself, along with information transmitted in subatomic particles and electromagnetic wave forms. We propose 'quantum nutrition' as an approach to reconcile quantum phenomena with nutritional biology. Appreciating quantum nutrition and recognizing its potential applications will provide opportunities for future health and well-being and for planetary habitability.

Ni Co -C/polyacrylamide hydrogels derived from mixed metal MOF-74 for synergistically enhanced electromagnetic wave absorption and thermal conduction performances

Ni Co -C/polyacrylamide hydrogels derived from mixed metal MOF-74 for synergistically enhanced electromagnetic wave absorption and thermal conduction performances

Identification and information acquisition of high-value construction solid waste combined millimeter-wave radar and convolutional neural networks.

The accumulation of construction solid waste (CSW) leads to the waste of land resources and environmental pollution, becoming a significant social problem. Identifying the amount of high-value CSW is essential for assessing the value of accumulated CSW and formulating appropriate recycling strategies. With the development of machine learning technology, CSW recognition techniques combining image acquisition devices and convolutional neural networks have been widely applied. However, most technologies are based on 2D images, making it difficult to recognize high-value CSW in accumulated CSW. This study proposes a new method to identify high-value CSW using millimeter wave radar based on penetration properties of electromagnetic waves. First, efficient imaging of CSW was achieved by optimizing the imaging algorithm. Then, CSW were classified in combination with the selected convolutional neural network (CNN) method based on the dataset constructed in the lab. At last, high-value CSW was screened by normalizing the imaging algorithm. The findings indicate that the balance between imaging effect and efficiency is achieved when the step speed and height are 200mm/s and 4mm. The optimized imaging approach effectively captures images of CSW. Compared with SegNet and PSPNet, DeepLabv3+ can identify complete bricks and reinforcing bars precisely. The accuracy can reach 85.18%. Moreover, the millimeter-wave radar can determine the location and size of waste and can potentially acquire three-dimensional and buried information about waste.

Passive radiation heating smart fabric with underwater sensor and electromagnetic wave absorption

Passive radiation heating smart fabric with underwater sensor and electromagnetic wave absorption

Integrating nitrogen doping with multi-heterogeneous interfaces of NRGO/ZnFe2O4@PPy composite aerogels for efficient and wideband electromagnetic wave absorption

Integrating nitrogen doping with multi-heterogeneous interfaces of NRGO/ZnFe2O4@PPy composite aerogels for efficient and wideband electromagnetic wave absorption

Synergistic dielectric regulation strategy of one-dimensional MoO2/Mo2C/C heterogeneous nanowires for electromagnetic wave absorption

Dielectric-dielectric nanocomposites with excellent synergistic effects are considered as a prospective avenue for the development of high-performance microwave absorbers. In this work, one-dimensional MoO2/Mo2C/C heterogeneous nanowires were synthesized via a straightforward co-precipitation and in situ pyrolysis process. The components were modulated by adjusting the reduction temperatures to achieve tunable electromagnetic parameters thereby optimizing the dielectric loss. The results showed that the optimized MoO2/Mo2C/C composite exhibited a minimum reflection loss of -50.7 dB at an ultra-thin thickness of 1.8 mm and an effective absorption bandwidth of 6 GHz at 2.3 mm when the calcination temperature was 700 °C. Based on the studies of electromagnetic parameters and radar cross section simulation outcomes, both the interwoven one-dimensional structure and synergistic effects between the components have endowed the material with good impedance matching and introduced various loss mechanisms such as conductivity loss, multiple polarization relaxation, and multiple reflection/scattering. This work presented a viable strategy for the preparation of one-dimensional MoO2-based dielectric microwave absorption materials.

Metamaterials for electromagnetic wave manipulation: Advancements and future prospects

Metamaterials for electromagnetic wave manipulation: Advancements and future prospects

Permittivity measurement with uncertainty quantification in cement-based composites using ENNreg-ANet and high-frequency electromagnetic waves

Permittivity measurement with uncertainty quantification in cement-based composites using ENNreg-ANet and high-frequency electromagnetic waves

Advancements in 2D Titanium Carbide (MXene) for Electromagnetic Wave Absorption: Mechanisms, Methods, Enhancements, and Applications.

With the advent of the 5G era, there has been a marked increase in research interest concerning electromagnetic wave-absorbing materials. A critical challenge remains in improving the wave-absorbing properties of these materials while satisfying diverse application demands. MXenes, identified as prominent "emerging" 2D materials for wave absorption, offer unique advantages that are expected to drive advancements and innovations in this field. This review emphasizes the synthesis benefits provided by the unique structural characteristics of MXenes and the performance enhancements achieved through their combination with other absorbing materials. Material requirements, synthesis approaches, and conceptual frameworks are integrated to underscore these advantages. The study provides a thorough analysis of MXene-absorbing composites, going beyond basic classification to address preparation and modification processes affecting the absorption properties of MXenes and their composites. Attention is directed to synthesis techniques, structural design principles, and their influence on composite performance. Additionally, the potential applications of MXenes in electromagnetic wave absorbing devices are summarized. The review concludes by addressing the challenges currently confronting MXene materials and outlining expected developmental trends, aiming to offer guidance for subsequent research in this domain.

Ultrafast broadband spectroscopy of widely spread excitonic features in WSe2 nanosheets.

The performance of an optoelectronic device is largely dependent on the light harvesting properties of the active material as well as the dynamic behaviour of the photoexcited charge carriers upon absorption of light. Recently, atomically thin two-dimensional transition metal dichalcogenides (2D TMDCs) have garnered attention as highly prospective materials for advanced ultrathin solar cells and other optoelectronic applications, owing to their strong interaction with electromagnetic radiation, substantial optical conductivity, and impressive charge carrier mobility. WSe2 is one such extremely promising solar energy material. It has absorption throughout the UV-Vis-NIR region with the existence of four excitonic features, just like MoS2 and WS2. However, stability issues and the absence of any robust synthetic route limit their practical applications. Herein, we have successfully synthesized atomically thin stable WSe2 nanosheets using a very effective colloidal hot injection method and further studied the optical properties of this material using femtosecond transient absorption spectroscopy. We probed all four excitonic features of WSe2 spread throughout the visible region. The dynamics of the high-energy excitons were found to be distinctively slower when compared to their band edge counterparts, adding an additional advantage in optoelectronic applications. We delved further into the factors governing exciton dynamics within WSe2, uncovering the strong influence of the electronic band structure. Importantly, our study highlights the importance of all four excitonic features in a 2D TMDC material, which emerge in the system irrespective of the excitation wavelength and influence each other.

Observations of Cherenkov-Like Radial Wake in Water Waves.

Cherenkov radiation (CR) is a fascinating phenomenon that occurs not only in electromagnetic (EM)waves but also in water waves. The V-shaped wake formed by a moving object on the water surface results from the constructive interference of water waves of different wavelengths, similar to CR. We designed and fabricated a one-dimensional (1D) water wave crystal to analogize the behavior of moving particles in water waves. This crystal exhibits a band structure with both positive (positive group velocity) and negative slopes (negative group velocity), exciting and directing the water waves to produce forward and backward radiating wakes through a mechanism similar to CR. Notably, the radiation angle is easily adjustable. This method of regulating water wave wakes holds potential applications in scattering cancellation-based wake stealth, navigation technology, and fluid dynamics for future offshore vessels.

Network model and application in wellbore wireless communication of extremely low frequency electromagnetic waves

Network model and application in wellbore wireless communication of extremely low frequency electromagnetic waves

Integrated electromagnetic sensing system based on a deep-neural-network-intervened genetic algorithm

With the deepening integration of artificial intelligence (AI) and the Internet of Things (IoT) in daily life, electromagnetic sensing presents both attraction and increasing challenges, especially in the diversification, accuracy, and integration of sensing technologies. The remarkable ability of metasurfaces to manipulate electromagnetic waves offers promising solutions to these challenges. Herein, an integrated system for electromagnetic sensing and beam shaping is proposed. Improved genetic algorithms (GAs) are employed to design the metasurface with desired beams, while spatial electromagnetic signals sensitized by the metasurface are input into the GA enhanced by deep neural networks to sense the number of targets, their azimuths, and elevations. Subsequently, the metasurface device is designed as the hybrid mode combining tracking and avoidance in alignment with practical requirements and sensing outcomes. Simulation and experimental results validate the efficiency and accuracy of each module within the integrated system. Notably, the target sensing module demonstrates the capability to precisely sense more than 10 targets simultaneously, achieving an accuracy exceeding 98% and a minimum angular resolution of 0.5°. Our work opens, to our knowledge, a new avenue for electromagnetic sensing, and has tremendous application potential in smart cities, smart homes, autonomous driving, and secure communication.

Investigation on the Heating Effects of Intra-Tumoral Injectable Magnetic hydrogels (IT-MG) for Cancer Hyperthermia.

Capacitive-based radiofrequency (Rf) radiation at 27 MHz offers a non-invasive approach for inducing hyperthermia, making it a promising technique for thermal cancer therapy applications. To achieve focused and site-specific hyperthermia, external material is required that efficiently convert Rf radiation into localized heat. Nanomaterials capable of absorbing Rf energy and convert into heat for targeted ablation are of critical importance. In this study, we developed and evaluated an intra-tumoral injectable magnetic hydrogel (IT-MG) composed of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) impregnated in low molecular weight Hyaluronic Acid (HA) forming HA-SPIONs. Our systematic investigation revealed that HA-SPIONs exposed to Rf radiation produced significant temperature increases, reaching up to 50 °C. Further testing in tissue-mimicking phantom models showed consistent heating, with temperatures stabilizing at 43oC, ideal for localized hyperthermia. The ability of HA-SPIONs to act as an efficient localized heating agent when exposed to 27 MHz Rf radiation, reaching apoptosis-inducing temperature has not been previously reported. In conclusion, synergistic effects of IT-MG in both in-vitro and tumour mimicking phantom model demonstrates improved and localized hyperthermia facilitating adjuvant cancer treatment. &#xD.

Switchable Bifunctional Chiral Metasurface Based on Vanadium Dioxide for Terahertz Waves

A switchable chiral metasurface (CM) with high polarization conversion ratio (PCR) and absorptivity based on vanadium dioxide (VO2) is proposed and numerically demonstrated in the terahertz (THz) regime. The proposed design consists of VO2–Au‐mixed resonant pattern layer, Si dielectric layer, and Au ground plate, which can achieve tunable bifunctional linear polarization conversion (LPC) and absorption (ABS) by varying the conductivity of VO2 (). For = 10 S m−1, the designed CM possesses a function of broadband LPC. More than 90% PCR is obtained in 1.79–2.46 THz, and the corresponding relative bandwidth (RBW) is 31.28%. For = 2 × 105 S m−1, the designed CM can efficiently absorb incident electromagnetic (EM) waves in 1.54–2.76 THz with the absorptivity exceeding 90% (RBW = 56.47%). The mechanisms of LPC and ABS are analyzed. The effects of geometric and EM parameters, incident angle, and polarization angle on its bifunctional characteristics are also studied. The LPC and ABS performances are maintained within a certain range of incident angles. Furthermore, the proposed CM exhibits polarization insensitivity. The developed switchable bifunctional CM has great potential application value in advanced THz research and smart device.

Comparative experimental validation of microwave hyperspectral atmospheric soundings in clear-sky conditions

Abstract. Accurate observations of atmospheric temperature and water vapor profiles are essential for weather forecasting and climate change detection. Hyperspectral radiance measurements afford a useful means to retrieve these thermodynamic variable fields by harnessing the rich information contained in the electromagnetic wave spectrum of the atmospheric radiation. In contrast to infrared radiometry, microwave radiometry can penetrate clouds, making it a valuable tool for all-sky thermodynamic retrievals. Recent advancements have led to the fabrication of a hyperspectral microwave radiometer: the High Spectral Resolution Airborne Microwave Sounder (HiSRAMS). This study utilizes HiSRAMS to retrieve atmospheric temperature and water vapor profiles under clear-sky conditions; this is an initial assessment of one of the first hyperspectral microwave radiometers, comparing the results to those from an infrared hyperspectrometer, the Atmospheric Emitted Radiance Interferometer (AERI). HiSRAMS and AERI measurements under different viewing geometries have been acquired and compared for atmospheric retrieval. When both instruments are placed on the ground to acquire zenith-pointing measurements, the infrared hyperspectral measurements exhibit higher information content and greater vertical resolution for temperature and water vapor retrievals than the microwave hyperspectral measurements. A synergistic fusion of HiSRAMS and AERI measurements from the air and ground is tested. This “sandwich” sounding of the atmosphere takes advantage of the complementary information contents of the two instruments and is found to notably improve retrieval accuracy.

Accurate equivalent circuit design of an ultra-broadband composite absorber

The combination of circuit analog absorber (CAA) and honeycomb absorbing material (HAM) has the advantages of lower profile, wider absorption bandwidth, and strong absorption performance. However, the increase in the number of CAA interlaced with various dielectric spacers makes the design and optimization of this complex multi-layer structure more difficult. Here, an accurate equivalent circuit model (ECM) of the multi-layer lossy single-square loop (SSL) metal-grounded is developed, which can be used to quickly design and optimize absorbers with the aid of genetic algorithm (GA). Based on the guideline, a lightweight composite absorber consisting of a double-layer impedance-sheet CAA at the top and a HAM at the bottom is developed. It covers an ultra-wideband -10 dB reflection reduction in the frequency band of 0.83 to 18 GHz with a fractional bandwidth of 182% in a total thickness of 35 mm and only 4% over the minimum thickness calculated by the Rozanov limit. The CAA is responsible for the absorption at a lower frequency, while the HAM absorbs the incident electromagnetic waves at the higher end of the frequency spectrum. The agreement between the experimental and simulated results verifies the viability of our design approach.

Signatures of dark and baryonic structures on weakly lensed gravitational waves

Gravitational lensing offers a powerful tool for exploring the matter distribution in the Universe. Thanks to their low frequencies and phase coherence, gravitational waves (GWs) allow for the observation of novel wave-optics features (WOFs) in lensing, inaccessible to electromagnetic signals. Combined with the existing accurate source models, lensed GWs can be used to infer the properties of gravitational lenses. The prospect is particularly compelling for space-borne detectors, where the high signal-to-noise ratio expected from massive black hole binary mergers allows WOFs to be distinguished deep into the weak lensing regime, drastically increasing the detection probability. Here, we investigate in detail the capacity of the LISA mission to detect WOFs caused by dark matter halos, galaxies, and the supermassive black holes (SMBHs) within them. We estimate the total optical depth to be λtot∼6×10−3 for the loudest binaries of total mass MBBH∼106M⊙, with the dominant contribution coming from SMBHs. We also find that WOFs in low-mass binaries MBBH∼104M⊙ are more likely due to the central galaxies. Within our model of gravitational lenses, we predict O(0.1)−O(1) weakly lensed events to be detectable during the five years of LISA mission, depending on the source population models. We show that WOFs signatures are very sensitive to the properties of dark matter halos with Mvir∈(106–108)M⊙: Increasing the compactness parameter by ∼3 in that range raises the detection rate by ∼26. Additionally, we show that collective effects from the complex inner halo structure can further enhance detectability. This suggests that lensed GWs in LISA will be an excellent probe of dark-matter theories, baryonic, and halo substructures. Published by the American Physical Society 2025