Polarization Separation Research Articles

Separation and interference of polarization in radially polarized Laguerre-Gaussian beams

The angular momentum properties of light can be described mathematically in terms of a higher-order Poincaré ball. The superposition of spin angular momentum (SAM) and orbital angular momentum (OAM) quantum states produces novel laser beams with unique spatial structures, which have great potential for applications in microscopic imaging, optical manipulation, and materials processing. Currently, researchers have developed a variety of techniques for preparing and controlling structured beams. In this study, a novel all-solid-state semiconductor side-pumped laser is introduced, which utilizes a thermal lens to image chromatic aberration, which is different from conventional chromatic aberration, a phenomenon that originates from the difference in the magnitude of the refractive indices tangentially and radially polarized light in the side-pumped Nd:YAG crystals, wherein the radial polarization is thermally less focalized as compared to the azimuthal polarization, thus enabling a stable mode selection through spherical aberration. Mode selection through spherical aberration is achieved by directly synthesizing a stable Laguerre-Gaussian (LG) radially polarized beam in a resonant cavity. The theoretical analysis explores the superposition states of two beams, LG + 01 and LG-01, with opposite topological charges, and the effect of the hot lens position on the output beam characteristics. In the experiments, we designed a semiconductor transversely pumped Nd:YAG laser. The obtained radially polarized Laguerre-Gaussian beams are formed by the superposition of circularly polarized vortex beams of opposite chirality. The circularly polarized vortex beams with opposite chiralities are separated by a separation device, and then interference experiments are performed separately to observe the interference patterns with obvious bifurcations and verify the theoretical analysis. The proposed method provides a direct and simple way to generate structured laser beams.

Miniaturized high-efficiency snapshot polarimetric stereoscopic imaging

Stereoscopic imaging reveals the 3D morphology of objects by collecting dense optical data from multiple views. However, traditional active methods rely on structured light illumination, while passive methods require substantial bulky optical components, hindering the development of portable, real-time stereoimaging systems. Here, we demonstrate miniaturized passive snapshot polarimetric stereoscopic imaging (SPSIM) using a polarimetric metalens. This protocol outperforms commercial polarimetric cameras in efficiency and enables the separation of circular polarization (CP) components for full Stokes parameter acquisition. By incorporating polarimetric physical priors into the neural network, we significantly enhance the accuracy of the 3D reconstruction process, enabling instant stereoimaging from a single shot with low mean absolute error. The inclusion of CP information improves 3D surface detail reconstruction, achieving depth precision within 0.15 mm. Our SPSIM system is well suited for integration into miniaturized devices for use in extreme environments, while advancing next-generation high-resolution 3D imaging systems.

Advanced Optical Encryption Using Tunable Color and Polarization Separation in In-Situ Polymerized Chiral Liquid Crystals.

With the rapid advancement of modern communication technologies, safeguarding information against forgery and unauthorized access has become increasingly critical, driving interest in advanced optical encryption systems. These systems excel in parallel image data processing, enabling swift detection and verification of sensitive information. However, traditional light-based encoding methods are constrained by their limited dependence on static parameters such as light wavelength and intensity and lack dynamic, reversible adaptability. To overcome these limitations, we propose an optical cryptography system that utilizes the tunable color and polarization selectivity of in situ polymerized, multicolor patterned chiral liquid crystals. This system capitalizes on the multifunctional optical properties of chiral liquid crystals, including thermally induced phase transitions that allow reversible and repeatable tuning, rendering encoded information unidentifiable until specific conditions are met. Furthermore, the system incorporates advanced disguising mechanisms through color separation, revealing accurate information only under predefined conditions. Key to its enhanced functionality is the integration of circular polarization selectivity, enabling electrically switchable polarization separation. This feature facilitates the display of distinct information under right- or left-handed circularly polarized light. By exploiting the dynamic optical properties of chiral liquid crystals, our system offers a multilevel encryption platform that significantly enhances data security. This versatile approach surpasses the limitations of conventional methods, providing a robust solution for secure data encoding and anticounterfeiting applications.

Theoretical design of manipulating the number of photonic spin Hall effect channels with Tamm plasmon polariton and its sensing capabilities

In this paper, the induction effect of Tamm plasmon polariton (TPP) mode on photonic spin Hall effect (PSHE) is discovered. As the incident angle increases, the TPP mode exhibits a polarization separation effect, which is conducive to the emergence of PSHE. PSHE is excited near the absorption frequencies of both the TM and TE waves, with H displacement dominating the TM wave and V displacement dominating the TE wave. The number of TPP channels is usually half that of PSHE, which enables quantitative control over the number of PSHE. In addition, the obtained PSHE has more potential as a sensor. On the one hand, compared with the TPP absorption peak, the PSHE peak is narrower, making a ten-fold increase in resolution. Different channels of PSHE can be used to detect different refractive index (RI) ranges, thus expanding the linear range. Moreover, analyzing PSHE displacement helps capture subtle RI changes, which is beneficial to the detection of gases, while the TPP peak fails to possess this ability.

Sulfur Vacancy-Induced Enhancement of Piezocatalytic H2 Production in MoS2.

This study explores the role of S vacancies in MoS2 in enhancing its piezocatalytic efficiency. Sulfur vacancies in the crystal lattice introduce localized changes in the electronic structure and charge distribution, improving the material's piezoelectric response. Characterization of the catalysts involved techniques like field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements, including impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis, are performed to assess the piezocatalytic performance. The study also employed density functional theory (DFT) calculations to investigate the electronic structure and hydrogen adsorption properties of MoS2 with S vacancies. The results demonstrated that S-deficient MoS2 significantly enhanced piezocatalytic H2 evolution. The piezocatalytic H2 production rates of MoS2 with different vacancy concentrations are measured under ultrasonic vibration. The sample with an optimal vacancy concentration (MS-1) exhibited the highest H2 production rate of 1423.29µmol g-1 h-1, compared to 439.06µmol g-1 h-1 for pristine MoS2 (MS-0). The improved performance is attributed to the increased piezoelectric polarization and efficient charge separation facilitated by S vacancies.

A Design Study on Polarized Beam Splitter for Visible Light

This study employs the thin film design software TFCale to successfully design and realize a high-efficiency polarization beam splitter suitable for the visible light wavelength range of 400-700 nm, with incident angles between 40 and 50. The design objective was to achieve near 100% reflectance for S-polarized light and near 100% transmittance for P-polarized light. By optimizing the refractive index, thickness, and multilayer structure of the thin film materials, we achieved high-performance optical characteristics. During the design process, we conducted an in-depth investigation of the optical constants of various materials and combined the interference effects of multilayer films to ensure the desired polarization splitting effect within the specified range of incident angles. Simulation results indicate that the film exhibits high-efficiency polarization separation across the entire visible spectrum: the reflectance of S-polarized light remains above 80% within a certain angular range, and the transmittance of P-polarized light also remains above 80%. This high-efficiency polarization beam splitter has broad application prospects in optical instruments, laser systems, display technologies, and other fields requiring precise polarization control. Its superior performance not only enhances the efficiency and accuracy of optical systems but also provides valuable references for future optical thin film design. The study demonstrates that using TFCale for thin film design is an effective method to meet complex optical performance requirements and offers reliable solutions for practical applications

Molecular-Level Insights into Recalcitrant Ozonation Products from Effluent Organic Matter.

Wastewater ozonation is commonly employed to enhance the subsequent biodegradation of effluent organic matter (EfOM) and contaminants of concern. However, there is evidence suggesting the formation of recalcitrant ozonation products (OPs) from EfOM. To investigate the biodegradability of OPs we conducted batch biodegradation experiments using wastewater effluent ozonated with mass-labeled (18O) ozone. Molecular level analysis of EfOM was performed using reversed-phase liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (LC-FT-ICR MS) after 3 and 28 days in batch bioreactors. The use of mass labeling allowed for the unambiguous detection of OPs, with 2933 labeled OP features identified in the ozonated EfOM. Furthermore, employing polarity separation with LC facilitated the investigation of reactivity among different OP isomers. Overall, OPs exhibited a comparable proportion of recalcitrant and bioproduced molecular formulas when compared to the remaining EfOM, with 12% of OPs classified as recalcitrant and 17% bioproduced, indicating that OPs themselves are not inherently biodegradable. Additionally, recalcitrant OPs were found to be more polar based on the O/C ratios and retention time, in comparison to biodegradable OPs. Approximately one-third of the OP isomers displayed variations in their biodegradability, suggesting that studying the degradability of ozonated EfOM at the molecular formula level is heavily influenced by structural differences. Here, we offer unique insight into the biological transformation of EfOM after ozonation using labeled ozone and LC-FT-ICR MS analysis.

Research on center-assisted ring-core few-mode fiber with an eccentric circle for mode degeneracy separation in space division multiplexing

An eccentric-circle-assisted ring-core fiber (ECRF) structure is proposed to effectively separate spatial-degenerated linear polarization (LP) modes while maintaining birefringence at the 10−6 level, which provides more degrees of freedom in the design of few-mode fiber employment in space division multiplexing (SDM) systems. Our simulation analysis demonstrates that the effective refractive index difference (Δneff) between the spatially degenerate modes in this fiber falls within the range of (2.44−6.42)×10−4 at 1530–1565 nm, given the refractive index difference level typical of conventional fiber core and cladding. In addition, the polarization separation level for each mode is on the order of 10−6 and below. The design requirements of significant separation of spatial degeneracy and basically no separation of polarization degeneracy are achieved. Based on the characteristics of spatially degenerate mode in this fiber, we extend the regulation law for spatially degenerate mode separation of the LP m n mode groups in center-assisted ring-core fibers. In comparison to the existing center-assisted ring-core fiber structure, the ECRF can further reduce the fabrication difficulty and increase the feasibility of preparation.

Small-Scale Light Structures in a Kerr Medium

A system of equations has been proposed for a monochromatic weakly nonlinear light wave in a Kerr medium. This system is equivalent up to the third order in electric field to the known equation , but the new equations are much more convenient for numerical computation. Optical fields with small structures of two or three wavelengths have been simulated using this system. It has been found that a stable self-focused light beam (a two-dimensional vector soliton) in some parametric domain is possible even without modification of nonlinearity. “Inelastic” collisions between two such narrow beams with opposite circular polarizations have been calculated. Furthermore, examples of interacting optical vortices, spatial separation of the circular polarizations, and the Kelvin–Helmholtz instability have been given for defocusing nonlinearity.

Simultaneous metabolomics and lipidomics analysis based on 4in1 online analysis system reveal metabolic signatures in atherosclerotic mice

Simultaneous metabolomics and lipidomics analysis based on 4in1 online analysis system reveal metabolic signatures in atherosclerotic mice

High-sensitivity fiber temperature sensor based on composite film structure and lossy mode resonance

High-sensitivity fiber temperature sensor based on composite film structure and lossy mode resonance

Identifying polar and non-polar octahedron units in isomorphic layered perovskites towards efficient piezocatalytic H2 evolution

Identifying polar and non-polar octahedron units in isomorphic layered perovskites towards efficient piezocatalytic H2 evolution

Highly polarized energetic electrons via intense laser-irradiated tailored targets

A method for the generation of ultrarelativistic electron beams with high spin polarization is put forward, where a tightly focused linearly polarized ultraintense laser pulse interacts with a nonprepolarized transverse-size-tailored solid target. The radiative spin polarization and angular separation is facilitated by the standing wave formed via the incident and reflected laser pulses at the overdense plasma surface. Strong electron heating caused by transverse instability enhances photon emission in the density spikes injected into the standing wave near the surface. Two groups of electrons with opposite transverse polarization emerge, antialigned to the magnetic field, which are angularly separated in the standing wave due to the phase-matched oscillation of the magnetic field and the vector potential. The polarized electrons propelled into the plasma slab are focused at the exit by the self-generated quasistatic fields. Our particle-in-cell simulations demonstrate the feasibility of highly polarized electrons with a single 10 PW laser beam, e.g., with polarization of 60% and charge of 8 pC selected at energy of 200 MeV within 15 mrad angle and 10% energy spread. Published by the American Physical Society 2024

The Overlooked Role of Humin in Dark Hydroxyl Radical Production during Oxygenation.

Humin, endowed with abundant redox functional groups, can be reduced anaerobically under dark. When reduced humin encounters O2, the possibility of ·OH formation arises. However, the exploration of ·OH generation mediated by humin has not been comprehensively conducted. The study found that O2 oxidized the reduced humin, generating 8.61 μmol/g of ·OH. After isolating humin using the methyl isobutyl ketone (MIBK) method, the lipid component was identified as the primary contributor to ·OH generation. Subsequent polar separation revealed that the lipid fraction extracted from the ethanol-water mixture with a volume ratio of 7:3 (LFEW7:3) played the most significant role in ·OH production. Further characterization confirmed that the simultaneous presence of aromatic C═C and C═O were the predominant features contributing to the ·OH generation. The ·OH generation experiments with humin-pyridine analogue compound demonstrated that polycyclic pyridine N (≥3 rings) played a significant role in promoting the ·OH generation. Most importantly, the study compared the ·OH production by humin and homologous humic acid, indicating that ·OH generated by humin was higher than that of humic acid. Overall, these affirmative findings manifested the overlooked role of humin in ·OH production and offered valuable insights into the mechanism of ·OH generation by humin in the dark.

Spectroscopic, anti-cancer, anti-bacterial and theoretical studies of new bivalent Schiff base complexes derived from 4-bromo-2,6-dichloroaniline

Spectroscopic, anti-cancer, anti-bacterial and theoretical studies of new bivalent Schiff base complexes derived from 4-bromo-2,6-dichloroaniline

Topological polarization beam splitter based on directional coupling between asymmetric valley photonic crystal waveguides.

Compared with symmetric directional couplers (DCs), asymmetric DCs constructed by two or over two different parallel waveguides offer a more flexible structure and allow for easier expansion of mode channels. In this Letter, we propose a kind of asymmetric topological DC based on two different valley photonic crystal waveguides (VPCWs). According to the coupled-mode theory, phase matching induces the complete coupling for the guide modes of two different VPCWs, whereas significant phase mismatching indicates no coupling occurs. Furthermore, the asymmetric topological DCs exhibit backscattering immunity and anti-disturbance robustness owing to the topological edge states (TESs), which greatly improve the performance of asymmetric DCs. We further design a new, to the best of our knowledge, kind of topological polarization beam splitter (TPBS) at the communication wavelength of 1550 nm by ensuring that the transverse electric mode satisfies the phase matching condition, while the transverse magnetic mode is phase-mismatched. The simulated results demonstrate that the proposed TPBS exhibits highly effective polarization separation and is robust against defects. This design holds significant potential for applications in optical communication systems.

An adhesive hydrogel functionalized silica sphere for polar analytes separation and analysis

An adhesive hydrogel functionalized silica sphere for polar analytes separation and analysis

Comprehensive analysis of chemical and enantiomeric stability of terpenes in Cannabis sativa L. flowers.

Cannabis sativa L. is renowned for its medicinal and recreational uses. With the increasing global legalization of C.sativa L.-based products for medicinal purposes, there is a growing need for well-characterized products. While the stability of cannabinoids such as tetrahydrocannabinol and cannabidiol is well understood, information on the chemical and enantiomeric stability of terpenes remains scarce. This is despite the fact that terpenes are also thought to have pharmacological activity and may contribute to the overall effect of C.sativa L. To address these challenges, four analytical methods based on chiral, polar, and apolar gas chromatographic separation combined with either MS or FID detection were developed and validated. These methods successfully separated and quantified a total of 29 terpenes, including 13 enantiomers and 5 diastereomers specific to C.sativa L. Furthermore, terpenes and authentic C.sativa L. flowers and extracts were subjected to UV and heat treatments to observe potential degradation reactions over time. Each terpene generates a unique pattern of degradation products resulting in a diverse array of oxidation and cyclization products. P-cymene was identified as a major product of terpene aging. Notably, no enantiomeric conversion was detected, suggesting that the formation of (-)-α-pinene in cannabis extracts, for example, originates from other terpenes. Terpenes have different degradation rates, even though they are structurally similar. In addition, cultivar- and growth-condition-specific enantiomeric ratios were observed in C.sativa L., confirming that enantiomer production is species-specific and has to be considered for therapeutical applications.

Snapshot spectropolarimeter based on a six-fold separating prism operating from 360 nm to 1 µm.

We describe a new type of spectropolarimeter in which light is separated to simultaneously measure six spectra carrying polarimetric information on a 2D CMOS camera. The polarization separation along one of the camera axes was obtained using a novel prism, and the spectral dispersion along the other camera axis was obtained using an imaging spectrometer. An ideal version of the six-fold separating prism is first described, in which polarimetric separation is performed along the canonical polarization states used to define the Stokes vector, and it can be explained without any math. The real version is then presented, with math that is simple for those familiar with polarization. The operation of the spectropolarimeter is described. Experimental results show that the polarimetric accuracy is a few 10-3, and noise (mainly due to shot noise) is in the same range for a single acquisition. The spectral resolution depends on the entrance pinhole width and can be as low as 2 nm. Several examples are presented that feature how informative snapshots, high spectral resolution, spectropolarimetric measurements can be. The anticipated applications of this spectropolarimeter and, more broadly, for this novel polarization-separating prism are discussed. Technical details, such as the calibration procedure, noise levels, and consistency checks, are presented as supplementary material.

IQ-channel multiplexed DP-4ASK signal using power loading for downlink coherent PON system with access-span length difference

IQ-channel multiplexed DP-4ASK signal using power loading for downlink coherent PON system with access-span length difference