Polarization Characteristics Research Articles

Spectrum and Polarization-Resolved Nonlinear Optical Near-Field Imaging of Plasmonic Nanoantennas.

Plasmonic nanoantennas, which support surface plasmon resonances enabling the concentration of electromagnetic energy into subwavelength volumes, have emerged as versatile tools for a wide range of applications. However, achieving high-resolution near-field imaging with polarization and temporal sensitivity remains a significant challenge. In this work, we present a novel nonlinear optical microscopy technique based on degenerate four-wave mixing to enable spectrum- and polarization-resolved near-field imaging of plasmonic nanoantennas. By using a mid-infrared pump and near-infrared probe, we capture detailed spatial distributions of plasmon-enhanced near-field intensity and polarization characteristics, revealing distinct polarization patterns and frequency-dependent enhancements. Our method enables the observation of resonance-induced spectral shifts and subwavelength spatial resolution, offering valuable insights into plasmonic field behaviors, particularly in the mid-infrared range. This approach provides a powerful tool for exploring and understanding the complexities of plasmonic nanostructures, with significant potential for advancing nano-optics applications.

Flexible circularly polarized CPW antenna for X-band: design, simulation, and experimental validation

Abstract This paper presents the design and analysis of a circularly polarized coplanar waveguide (CPW) antenna specifically tailored for X-band applications. The antenna, with compact dimensions of 27 mm x 28 mm, is fabricated on a flexible 0.1 mm thick polyimide substrate. It operates effectively within the frequency range of 10.5 GHz to 12 GHz. To enhance performance metrics such as gain and radiation characteristics, two complementary split-ring resonators (CSRRs) are integrated into the radiating patch. Comprehensive simulations were conducted, followed by the fabrication and experimental testing of the antenna. The results indicate a high degree of agreement between the simulated and measured performance parameters. The antenna achieves a gain of up to 6 dBi, with an axial ratio maintained below 3 dB across the operating frequency band, signifying excellent circular polarization characteristics. These findings underscore the potential of the proposed CPW antenna design as a highly efficient solution for X-band applications, offering notable improvements in gain and axial ratio performance. This work contributes to the development of advanced antenna technologies suitable for modern communication systems operating in the X-band spectrum.

Exploring the Role of Epithelial–Mesenchymal Transcriptional Factors Involved in Hematological Malignancy and Solid Tumors: A Systematic Review

Background: The epithelial mesenchymal transition (EMT) is a biological process in which epithelial cells lose their polarity and adhesion characteristics, and adopt a mesenchymal phenotype. While the EMT naturally occurs during tissue fibrosis, wound healing, and embryonic development, it can be exploited by cancer cells and is strongly associated with cancer stem cell formation, tissue invasiveness, apoptosis, and therapy resistance. Transcription factors (TFs) such as SNAIL, ZEB, and TWIST play a pivotal role in driving the EMT. This systematic review aims to assess the impact of EMT-TFs on hematological malignancy and solid tumors. Methods: English-language literature published between 2010 and 2024 was systematically reviewed, utilizing databases such as PubMed and Google Scholar. Results: A total of 3250 studies were extracted. Of these, 92 publications meeting the inclusion criteria were analyzed to elucidate the role of EMT-TFs in cancer. The results demonstrated that the EMT-TFs play a critical role in both hematological and solid tumor development and progression. They promote invasive, migratory, and metastatic properties in these tumors, and contribute to therapeutic challenges by enhancing chemoresistance. A strong correlation between EMT-TFs and poor overall survival has been identified. Conclusions: Our research concluded that EMT-TFs may serve as important predictive and prognostic factors, as well as potential therapeutic targets to mitigate cancer progression.

Quantitative Large-Area Polarized-Light Microscopy

Abstract This article describes the elevation of polarized-light microscopy (PLM) to a technique for quantitative large-area material characterization in the Microscopy Today Innovation Award-winning CrystalViewTM laser PLM. CrystalView is enabled by narrow-band laser illumination, bistatic design, and strict qualification of polarization optics, resulting in accurate polarization imaging over an instant field-of-view (FOV) that exceeds 2 cm2. This FOV is effectively demonstrated by the critical concept of seamless stitching, which confirms low error and is then applied to obtain even larger effective FOVs with industrial utility. Linear combinations of image irradiances, known as polarization features, are related to physical material properties, for instance, crystal orientation, through the combination of Mueller matrix polarimeter design and classical electrodynamics. While CrystalView is applicable to any reflective or transmissive material that exhibits PLM contrast, in this article it is demonstrated for orientation imaging of hexagonal and cubic metal polycrystals, titanium and stainless-steel alloys respectively, the latter printed by laser powder-bed fusion (LPBF) and reliant, for texture imaging, on chemical etching that can also reveal phase structure.

Aroma Compound Release from Starches of Different Origins: A Physicochemical Study

Sensory properties, particularly aroma, play a crucial role in consumers’ acceptance and perceived quality of food. The release and the perception of aroma compounds is affected by their interaction with nonvolatile ingredients of foods, such as proteins, lipids, and polysaccharides. These interactions, whether reversible or irreversible, significantly influence aroma retention and release. Starch, a common food constituent, has been found to interact with aroma compounds, impacting flavor dynamics through processes like complexation and encapsulation. In this study, reversed-flow gas chromatography (RF-GC) is employed for the estimation of the release behavior of polar (diacetyl) and non-polar (dl-limonene) aroma compounds from starches of various origins (corn, wheat, rice, and potato). The results show that aroma compound release is influenced by the matrix composition, environmental conditions, and physicochemical properties of both starch and aroma compounds. The temperature-dependent mass transfer coefficients and activation energies reveal the strong influence of polar and non-polar characteristics on aroma compound behavior. Additionally, significant variations in retention and release are observed based on the starch type and the type of bonds involved in aroma compound interactions, underscoring the critical role of thermodynamic and kinetic parameters in flavor dynamics.

A Direction-Finding Model With Spatial Polarization Characteristics

A Direction-Finding Model With Spatial Polarization Characteristics

Application of Hansen solubility parameters in the eutectic mixtures: difference between empirical and semi-empirical models

Hansen Solubility Parameters (HSPs) are widely used as a tool in solubility studies. Given the variety of existent approaches to predict these parameters, this investigation focused on estimating the HSPs of a set of Natural Deep Eutectic Systems (NADES), using empirical (EM) and semi-empirical models (SEM), and then understanding their differences/similarities. Although these theoretical models are designed and recommended mostly for simple molecules or simple solutions, they are still being used in eutectic systems studies, mainly empirical ones. Thus, a preliminary test was conducted with a set of conventional solvents, in which their experimental values of HSPs are known. Besides the confirmation of the EM as the most suitable for these kinds of regular solvents, the results found also showed a very similar behaviour to what was observed in NADES, i.e., in terms of suggesting the EM and SEM with the highest/lowest similarity. Furthermore, it was concluded that although there is a large discrepancy between the estimated values of the hydrogen bond parameter, especially for systems with a higher polar character, there is still a good similarity for the other parameters. In fact, it was observed that, when combining the semi-empirical models, it was possible to obtain a value of the hydrogen bond parameter more similar to the empirical ones.

Investigation of Electronic and Spintronic Properties in Co-Doped Graphene Nanodisks for Spin Filtering Applications

Graphene nanodisks (GNDs) have attracted significant attention due to their unique electronic and magnetic properties, offering promising prospects for applications in nanoelectronics and spintronic devices. In this study, we investigate the density of states (DOS), spin currents, and spin polarization characteristics of pristine and Co-doped diamond-shaped and triangular GNDs using first-principles calculations. Our results reveal that Co doping induces spin splitting within the band gap of diamond-shaped GNDs, indicating spin-dependent phenomena. Additionally, fine spin splitting and metallic behavior are observed in the DOS of triangular GNDs. Through I-V curve analysis, we demonstrate that Co-doped diamond-shaped GNDs exhibit spin switch behavior and polarized spin currents, with a notable increase in peak current and polarization compared to pristine GNDs. The introduction of Co impurities enhances the spin filtering capabilities, making the device act as a spin filter in a wide voltage range. These findings provide valuable insights into the electronic and spintronic properties of Co-doped GNDs, offering possibilities for the development of efficient spintronic devices and spin filtering applications.

Effect of electronic nature of substituent position on the linear and nonlinear optical and physical properties of some quinoline derivatives. A computational study

In this work, we have performed a computational study of the linear and nonlinear optical, physical and chemical properties of some quinoline derivatives within density functional theory (DFT) using PBE/6-311G++(d, p) theoretical level . The molecular geometries have been analysed using the appropriate B3LYP/6-311++G(d,p) computational level. Linear optical such as the polarizability <α> and the polarizability anisotropy <Δα> and non-linear optical properties, namely the first hyperpolarizability βtot , electric field-induced second harmonic generation (EFISHG) β// have been calculated using COSMO model in DMSO solvent. The relation between electronic gap energy and the first hyperpolarisability β was also evaluated. Global conceptual reactivity descriptors and molecular electron potential analyses were performed, indicating that the electron density distribution along the studied structure makes it have a polar character, which leads to good non-linear optical properties. QTAIM analysis demonstrates that the presence of weak interaction in the 2-formyl-quinoline dimer may be the origin of the increases of the nonlinear optical properties. UV–Vis spectrum analysis indicates that 6-amino-2-formyl-quinoline may be used as a semiconductor organic material, which is considered a promising green energy organic material for possible future use as an alternative organic photovoltaic material in solar cells and other nonlinear optical applications.

Design and Application of Laser Polarization Underwater Detection Equipment

With the increasing demand for precise identification of underwater targets, the development of advanced underwater detection technologies has become a pivotal area of research. This study presents the design and implementation of a laser-based underwater detection system that leverages polarization characteristics to significantly enhance detection accuracy and target identification capabilities in complex aquatic environments. A key innovation of this research lies in the application of a dual-frequency modulation technology using a 532 nm pulsed laser. By modulating the high-frequency characteristics of the laser, this technique effectively suppresses backscattering interference within the water medium, improves the efficiency of target signal extraction, and exhibits exceptional performance, particularly in long-range detection and highly turbid water conditions. This paper elucidates the principles of underwater laser detection and polarization measurement, outlines the design of an integrated optical and mechanical system for laser transmission and reception, and introduces an optimized signal processing methodology. Experimental results demonstrate that the proposed system can reliably distinguish targets composed of different materials while maintaining high detection accuracy across a range of challenging environmental conditions. A comparative analysis further highlights the system’s significant advantages over traditional technologies, including enhanced noise suppression and greater detection depth. These findings establish a solid foundation for advancing underwater detection technologies and broadening their practical applications.

2D Perovskite Heterojunction-Based Self-Powered Polarized Photodetectors with Controllable Polarization Ratio Enabled by Ferro-Pyro-Phototronic Effect.

Metal halide perovskites (MHPs) are commonly used in polarization-sensitive photodetectors (PDs) for applications such as polarization imaging, remote sensing, and optical communication. Although various methods exist to adjust the polarization-sensitive photocurrent, a universal and effective approach for continuous control of MHPs' optoelectronic and polarized properties is lacking. A universal strategy to electrically modulate the polarization ratio (PR) of self-powered polarized PDs using the ferro-pyro-phototronic effect (FPPE) in 2D perovskites is presented. By varying the amplitude and direction of ferroelectric polarization voltage, the built-in electric field in the heterojunction can be modulated, allowing for controllable PR regulation and adjustable polarization characteristics. Moreover, the polarized pyroelectric photoresponses are realized, significantly enhancing the responsivity, response speed of the polarized PDs. Both the pyroelectric currents and photocurrents exhibit obvious polarization characteristics. This method's versatility is demonstrated by creating three additional quasi-2D MHP ferroelectric-based polarized-sensitive PDs. A proof-of-concept for encrypted optical communication is achieved using the UV-sensitive PDs as light-sensing units. These findings highlight FPPE's potential to enhance ferroelectric device polarization control, enabling high-performance and self-powered polarization photodetection.

Engineering Nonvolatile Polarization in 2D α-In2Se3/α-Ga2Se3 Ferroelectric Junctions

The advent of two-dimensional (2D) ferroelectrics offers a new paradigm for device miniaturization and multifunctionality. Recently, 2D α-In2Se3 and related III–VI compound ferroelectrics manifest room-temperature ferroelectricity and exhibit reversible spontaneous polarization even at the monolayer limit. Here, we employ first-principles calculations to investigate group-III selenide van der Waals (vdW) heterojunctions built up by 2D α-In2Se3 and α-Ga2Se3 ferroelectric (FE) semiconductors, including structural stability, electrostatic potential, interfacial charge transfer, and electronic band structures. When the FE polarization directions of α-In2Se3 and α-Ga2Se3 are parallel, both the α-In2Se3/α-Ga2Se3 P↑↑ (UU) and α-In2Se3/α-Ga2Se3 P↓↓ (NN) configurations possess strong built-in electric fields and hence induce electron–hole separation, resulting in carrier depletion at the α-In2Se3/α-Ga2Se3 heterointerfaces. Conversely, when they are antiparallel, the α-In2Se3/α-Ga2Se3 P↓↑ (NU) and α-In2Se3/α-Ga2Se3 P↑↓ (UN) configurations demonstrate the switchable electron and hole accumulation at the 2D ferroelectric interfaces, respectively. The nonvolatile characteristic of ferroelectric polarization presents an innovative approach to achieving tunable n-type and p-type conductive channels for ferroelectric field-effect transistors (FeFETs). In addition, in-plane biaxial strain modulation has successfully modulated the band alignments of the α-In2Se3/α-Ga2Se3 ferroelectric heterostructures, inducing a type III–II–III transition in UU and NN, and a type I–II–I transition in UN and NU, respectively. Our findings highlight the great potential of 2D group-III selenides and ferroelectric vdW heterostructures to harness nonvolatile spontaneous polarization for next-generation electronics, nonvolatile optoelectronic memories, sensors, and neuromorphic computing.

Mechanical and corrosion behaviour of Al7075 alloy reinforced with SiC and cenosphere particles

Hybrid composites are novel composites that can meet the demands of cutting-edge applications. They may be utilized to meet advanced applications by maximizing weight reduction by reducing adhesive film weight and performance through increased characteristics. The mechanical and corrosion study of Al 7075 hybrid metal matrix composites reinforced with weight percentage (wt.%) of silicon carbide 2, 4, 6, and 8 and 5 wt.% of cenosphere is studied in this work. Composites prepared by the liquid metallurgy route were studied at room temperature to estimate seawater's hardness, tensile strength, and corrosion rate for various silicon carbide (SiC) inclusions using the electrochemical method. The results revealed that an Al7075 hybrid composite reinforced with 6 wt.% SiC had a higher tensile strength of 263 MPa, an increase of approximately 43 MPa (20%) over the basic alloy. The hardness of the Al7075/SiC/cenosphere composite was 128 HV with the addition of wt.% SiC reinforcement. The actual density of the Al 7075/SiC/Cenosphere composite has resulted in increased density compared to the as-cast base metal. According to polarization characteristics in natural seawater, aluminum alloy reinforced with 8 wt.% SiC demonstrated an efficiency of 58.67%, whereas electrochemical impedance measurements in natural seawater indicated 76.91%. The hybrid Al7075 composite with 8 wt.% SiC has a reduced corrosion rate in saltwater compared to pure alloy. Tafel Polarization experiments demonstrate that the hybrid metal matrix composite with 8 wt.% SiC corroded at a lower rate than the base alloy. According to the micrographs, the SiC reinforcement with the matrix alloy reduced corrosion by forming strong interfacial and intermetallic bonding.

Tempo-spatially modulated Mueller matrix imaging polarimeter based on modified Savart polariscopes.

Mueller matrix polarization measurement technique, as a non-invasive and label-free, provides comprehensive optical information on polarization-related and structural characteristics of the measured target. It has been widely applied in biomedical, agricultural, and industrial fields. However, the traditional time-division modulation Mueller matrix measurement method requires multiple measurements, which suffers from long measurement time and susceptibility to cumulative errors from moving parts. The snapshot spatial modulation method can capture the target's interferograms and the full Mueller matrix element images in a single exposure, but it suffers from lower spatial resolution. To address the strengths and limitations of both temporal and spatial modulation, this paper proposes a tempo-spatially modulated Mueller matrix imaging polarimeter (TSM-MMIP). This approach is based on the Stokes imaging polarimeter with the modified Savart plates as the core device, allowing the acquisition of the 16 Mueller matrix elements of the target with only four measurements. Through computer simulation and experimental platforms, we validate that the structural similarity of Mueller matrix elements between input and output exceeds 0.85, which demonstrates the reliability and feasibility of the proposed method. In addition, we use a bee wing as a target to reveal the potential of this technique to analyze the polarization characteristics of targets by extracting and analyzing key parameters of the Mueller matrix.

THE POLAR CHARACTERISTIC OF AN ACOUSTIC PARABOLIC REFLECTOR

The first part of the paper presents the geometry of the acoustic parabolic reflector. After that, analytical formulas for calculating the amplification and polar characteristics of the reflector are shown. The second part of the paper describes the experiment in which measurements were made and the acoustic characteristics of the parabolic reflector located in the yard of the Academy of Applied Technical and Preschool Studies, Department of Niš, in Niš were calculated. First, acoustic impulse responses for acoustic excitation at angles from -90° to 90° were measured. After that, the polar characteristic of the radiation was calculated. Finally, the beamwidth of the radiation, beam solid angle of the radiation, and directivity of the acoustic parabolic reflector were determined. The results of the experiment are presented numerically and graphically.

Classification and Monitoring of Salt Marsh Vegetation in the Yellow River Delta Based on Multi-Source Remote Sensing Data Fusion.

Salt marsh vegetation in the Yellow River Delta, including Phragmites australis (P. australis), Suaeda salsa (S. salsa), and Tamarix chinensis (T. chinensis), is essential for the stability of wetland ecosystems. In recent years, salt marsh vegetation has experienced severe degradation, which is primarily due to invasive species and human activities. Therefore, the accurate monitoring of the spatial distribution of these vegetation types is critical for the ecological protection and restoration of the Yellow River Delta. This study proposes a multi-source remote sensing data fusion method based on Sentinel-1 and Sentinel-2 imagery, integrating the temporal characteristics of optical and SAR (synthetic aperture radar) data for the classification mapping of salt marsh vegetation in the Yellow River Delta. Phenological and polarization features were extracted to capture vegetation characteristics. A random forest algorithm was then applied to evaluate the impact of different feature combinations on classification accuracy. Combining optical and SAR time-series data significantly enhanced classification accuracy, particularly in differentiating P. australis, S. salsa, and T. chinensis. The integration of phenological features, polarization ratio, and polarization difference achieved a classification accuracy of 93.51% with a Kappa coefficient of 0.917, outperforming the use of individual data sources.

Abraham model expressions for correlating and predicting solubilities and molar solubility ratios of crystalline nonelectrolyte organic compounds in dibutyl adipate

ABSTRACT Abraham model correlations have been derived for solute transfer into the dibutyl adipate mono-solvent from both water and from the gas phase based on spectrophotometric solubility measurements for a chemically diverse set of 33 different crystalline organic compounds covering a wide range of polarity and hydrogen-bonding characteristics. The derived Abraham model correlations describe the observed molar solubility data to within an overall standard deviation of 0.13 log units. Comparison of the reported dibutyl adipate equations with those previously determined for dimethyl adipate reveal that the respective equations for both dialkyl adipate mono-solvents are essentially identical, at least to within the coefficient’s combined standard error.

A highly magnetized long-period radio transient exhibiting unusual emission features.

Long-period radio transients are a new class of astrophysical objects that exhibit periodic radio emission on timescales of tens of minutes. Their true nature remains unknown; possibilities include magnetic white dwarfs, binary systems, or long-period magnetars; the latter class is predicted to produce fast radio bursts (FRBs). Using the MeerKAT radio telescope, we conducted follow-up observations of the long-period radio transient GPM J1839-10. Here we report that the source exhibits a wide range of unusual emission properties, including polarization characteristics indicative of magnetospheric origin, linear-to-circular polarization conversion, and drifting substructures closely resembling those observed in repeating FRBs. These radio characteristics provide evidence in support of the long-period magnetar model and suggest a possible connection between long-period radio transients, magnetars, and FRBs.

Polarization Scattering Regions: A Useful Tool for Polarization Characteristic Description

Polarimetric radar systems play a crucial role in enhancing microwave remote sensing and target identification by providing a refined understanding of electromagnetic scattering mechanisms. This study introduces the concept of polarization scattering regions as a novel tool for describing the polarization characteristics across three spectral regions: the polarization Rayleigh region, the polarization resonance region, and the polarization optical region. By using ellipsoidal models, we simulate and analyze scattering across varying electrical sizes, demonstrating how these sizes influence polarization characteristics. The research leverages Cameron decomposition to reveal the distinctive scattering behaviors within each region, illustrating that at higher-frequency bands, scattering approximates spherical symmetry, with minimal impact from the target shape. This classification provides a comprehensive view of polarization-based radar cross-section regions, expanding upon traditional single-polarization radar cross-section regions. The results show that polarization scattering regions are practical tools for interpreting polarimetric radar data across diverse frequency bands. The applications of this research in radar target recognition, weather radar calibration, and radar polarimetry are discussed, highlighting the importance of frequency selection for accurately capturing polarization scattering features. These findings have significant implications for advancing weather radar technology and target recognition techniques, particularly as radar systems move towards higher frequency bands.

Channeled Polarimetry for Magnetic Field/Current Detection.

Magneto-optical magnetic field/current sensors are based on the Faraday effect, which involves changing the polarized state of light. Polarimetric methods are therefore used for measuring polarization characteristics. Channeled polarimetry allows polarization information to be obtained from the analysis of the spectral domain. Although this allows the characterization of Faraday materials, the method has not yet been used for detection in magneto-optical sensors. This paper reports experimental results for magnetic field/current detection using the channeled polarimetry method. It is shown that in contrast to other methods, this method allows the detection of the phase shift caused by Faraday rotation alone, making the detection independent of temperature. Although an increase in measurement accuracy is required for practical applications by refining the data processing, the experimental results obtained show that this method offers a new approach to improving the performance of magneto-optical current sensors.