Polarization Degree Of Light Research Articles

Probing the enpolarization phenomenon in a speckle pattern using a microwave photonics-inspired approach.

We report how Stokes polarimetry of a highly resolved optical speckle pattern coupled to an original microwave photonics-inspired experimental approach allows new light to be shaded on the so-called enpolarization phenomenon, which consists in the local increase of the light degree of polarization (DOP) inducing a high average DOP value after interaction of unpolarized light with a totally depolarizing sample.

Noninvasive evaluation of the skin barrier in reconstructed human epidermis using speckle analysis: Correlation with Raman microspectroscopy.

Reconstructed epidermis models, obtained from 3D keratinocytes culture, have gained significant prominence as prototypes for safety and efficacy testing in skin research. To effectively evaluate these models, it is essential to perform molecular and functional characterization. The skin's barrier function is one of the essential aspects of the epidermis that needs to be assessed. A noninvasive method is thus required for the evaluation of the skin barrier in these models. With this perspective, the aim of this feasibility study is to apply the speckle technique for the assessment of the skin barrier in the Reconstructed Human Epidermis (RHE). Speckle analysis as well as Raman microspectroscopy were performed on RHE samples at two maturation days, D17 and D20. Between D17 and D20, our study showed an increase in various Raman parameters, including stratum corneum percentage, lateral lipid packing, lipid-to-protein ratio, and protein secondary structure. Furthermore, the degree of light polarization and the speckle grain size also increased over this period. The speckle technique proved to be effective for evaluating the skin barrier in Reconstructed Human Epidermis (RHE) models. Comparison with Raman validates this approach and provides comprehensive molecular and functional characterization of reconstructive skin models.

Detection and identification of oil spill species based on polarization information.

Aiming at the problem of poor oil identification accuracy in existing oil spill detection technologies, the polarization degree model of oil spill on rough sea surface under different azimuths and zenith angles was established based on Fresnel theory. The analytical expressions of visible light polarization degree in calm and fluctuating water surface were derived respectively, and the polarization degree model of oil spill in reflection space was constructed. The effectiveness of the method and its influence on the polarization distribution of oil spill were analyzed by simulation. A portable turntable was designed to test the polarization characteristics of the experiment, and the visible light polarization detection experiment was carried out. The visible light polarization images of five typical oil spills at different observation azimuth and zenth angles were obtained. The differences in the polarization degrees of different oil species were analyzed, and the correctness of the theoretical model was proved by experiments. The polarization detection experiment of visible light pBRDF was completed, which more intuitively showed the variation law of the polarization characteristics of light reflected by different oil spills in different spatial positions. Using polarization information to distinguish oil species is a useful supplement to the traditional oil spill detection method and has important significance to improve the marine pollution control ability.

Polarized laser speckle images produced by calibrated polystyrene microspheres suspensions: comparison between backscattering and transmission experimental configurations

In this paper, we analyze polarized laser speckle images produced by calibrated polystyrene microspheres suspensions and discuss the results obtained while considering two different experimental configurations for light detection: speckle-transmission setup and speckle-backscattering one. The degree of light polarization (DOP) and speckle grain size (dx) were monitored in both cases. Results show that, when backscattered photons are detected, the degree of circular polarization allows a fine monitoring of the variation of scatterers concentration in a sample. A helicity flipping is detected as the scatterers concentration increases, showing that a transition from a simple scattering regime to a multiple scattering one is taking place. When transmitted scattered photons are detected dx is a better parameter than DOP for following changes in scattering regime: dx values initially increase slightly then decrease as the scattering coefficient increases. The observed maximum corresponds to the shift from a simple to a multiple scattering regime.

Negative Polarization of Celestial Bodies: Review and Computer Simulation

A brief review of the main causes of a negative degree of linear polarization of radiation scattered by regolith surfaces of atmosphereless cosmic bodies and ensembles of particles in the opposition region is presented. The results of computer simulation are provided, which made it possible to calculate the polariza tion degree of light scattered by pairs of irregular particles. The distance between the particles changed, which made it possible to obtain a visual representation of the total effect of the nature of negative polarization in the case of two-particle scattering (scattering in which two particles participate). Previously, a similar study was carried out for the case of two spherical particles, and showed that two-particle scattering by spheres only changes the degree of linear polarization in absolute value. We showed that two-particle scattering by irregular particles has a variable effect on the degree of linear polarization, both increasing and decreasing it. We also demonstrated that two-particle scattering by irregular particles can form a negative polarization even if the light scattered by a single particle is positively polarized. Therefore, in theoretical studies of the appearance of negative polarization, it is important to take into account two-particle scattering.

Двухфотонное внутризонное поглощение поляризованного света и его линейно-циркулярный дихроизм в алмазоподобных полупроводниках

The theory of interband two-photon absorption of a strong light wave in semiconductors with a complex band is developed. An analytical expression is obtained for the probability of a two-photon interband transition, which contains a dependence on the intensity, polarization vector, and frequency of the absorbed light, as well as on the band parameters of the semiconductor, where the contribution of the Rabi effect to the coefficients of two-quantum absorption of light is taken into account. It is shown that the shape of the absorption edge and linear-circular dichroism depends on the degree of light polarization and on the Rabi parameter.

Deterministic Relation between Optical Polarization and Lattice Symmetry Revealed in Ion-Doped Single Microcrystals.

Rare-earth ion doped crystals are of great significance for microsensing and quantum information, while the ions in the crystals emit light with spontaneous partial polarization, which is, though believed to be originated from the crystal lattice structure, still lacking a deterministic explanation that can be tested with quantitative accuracy. We report experimental evidence showing the profound physical relation between the polarization degree of light emitted by the doped ion and the lattice symmetry by demonstrating, with high precision, that the lattice constant ratio c/a directly quantifies the macroscopic effective polar angle of the electric and magnetic dipoles, which essentially determines the linear polarization degree of the emission. Based on this result, we further propose a pure optical technology to identify the three-dimensional orientation of a rod-shaped single microcrystal using the polarization-resolved microspectroscopy. Our results, demonstrating the physical origin of light polarization in ion-doped crystals, allow work toward on-demand polarization control with crystallography and provide a versatile platform for polarization-based microscale sensing in dynamical systems.

Image-restoration algorithm based on an underwater polarization imaging visualization model.

The polarization bidirectional reflection distribution function theory of a target is combined with microfacet theory, and the Monte Carlo method is used to establish an underwater laser active-polarization imaging model based on Mie scattering theory. The model presented herein can simulate imaging of an underwater target with a high degree of polarization, and the effects of optical thickness and target surface roughness on active underwater laser imaging results are demonstrated by the simulation image. Combined with histogram equalization and the traditional polarization differential imaging algorithm, an algorithm is presented herein that globally estimates the mutual information value between the target polarization degree and the correction factor of backscattered light polarization degree. The images received from the simulation test can be restored, and results show that the algorithm can restore the target image with a high degree of polarization to some extent. Finally, the correctness of the active underwater laser polarization imaging model and the feasibility of global estimation based on the polarization differential restoration algorithm are verified experimentally.

Abstract P041: Simultaneous checkpoint inhibition and immune cell activation that is safely localized to solid tumors

Abstract Unlike other checkpoint inhibitors, our targeted immunotherapeutic localizes to any solid tumor and simultaneously shields an agent of immunosuppression while presenting a signal for immunostimulation. Phosphatidylserine (PS) exposure on the extracellular surface of living tumor cells and their vasculatures provides one avenue by which the tumor microenvironment promotes immunosuppression. Extracellular surface PS is inherent to a tumor and its vasculature, even for inoperable tumors, and its expression cannot be mutated nor affected by acquired drug resistance. Annexin A5 (AnxA5) is a direct, high-affinity PS-binding protein that localizes to cells with PS exposed on the outer plasma membrane. In our studies, we conjugated a proprietary modified AnxA5, lacking cellular internalization, to TNFα (AnxA5MOD-TNFα) to convert the immunosuppresive environs of a murine 4T1 triple negative breast cancer (TNBC) into an immunostimulated one. This strategy localized the immune response to the tumor and minimized side effects, as evidenced by a lack of toxicity for up to 7 days in non-tumor bearing Balb/c female mice given up to 1 mg/kg. Proper assembly and functionality of AnxA5MOD-TNFα was verified simultaneously by ellipsometry, an optical technique similar to plasmon resonance. Fully assembled constructs were tested for binding to PS coated slides. The degree of light polarization is proportional to the amount of PS bound by the AnxA5 complex. Samples could be further incubated with TNF receptors to verify TNFα activity. Based on dose escalation studies in 4T1 tumor-bearing mice where the TNBC tumors were grown in the mammary fat pads, optimal dosages were determined for AnxA5MOD-TNFα (18 µg) and AnxA5MOD alone as a control (180 µg). These doses were further tested in a 4T1 growth inhibition study. Tumor size was tracked by caliper in two groups of mice (n=5/group) receiving drug treatment on days 12, 14 and 16 and a repeated measures ANOVA was conducted on measurements taken before, during and post-treatment. While median tumor size did not differ between control and drug treatment groups during the pre-treatment interval (p=0.84), there was a significant difference post-treatment (p<0.001) with mice receiving AnxA5MOD-TNFα having much smaller TNBC tumors. Tumors from the study were embedded in paraffin, sectioned (5 µm) and the overall immune cell content determined by H&E staining. Once it was evident there was a greater quantity of immune cells in AnxA5MOD-TNFα treated tumors vs. controls, sections were stained with validated antibodies to identify and count the immunoactivated T-cells, NK-cells and macrophages. There was a 3X greater mean percentage of CD8 and CD4 T-cells in mice receiving drug vs. control (p=0.03) along with 2.5X and 5X increases in NK-cells and M1 immunoactive macrophages, respectively. Conclusion: Our AnxA5MOD-TNFα inhibits the PS inhibitor while simultaneously activating TNF activators! Citation Format: Richard A. Richieri, Navneet Narula, Cynthia A. Loomis, Valeria Mezzano, John Billimek, Glenn T. Reynolds, Chris Reutelingsperger, Andries Zijlstra, Missag H. Parseghian. Simultaneous checkpoint inhibition and immune cell activation that is safely localized to solid tumors [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P041.

Relationship between degree of polarization and two-time degree of coherence of electromagnetic fields

For stationary light fields, the degree of polarization (DOP) of light relates to the maximum correlation between two arbitrarily decomposed orthogonal electric field components at a space–time point. We generalize this understanding theoretically by showing a physically insightful connection between DOP and the two-time degree of coherence of electromagnetic fields. Further, by using a variable path Mach–Zehnder interferometer, we experimentally demonstrate that the DOP of light can be directly determined by measuring the correlation between orthogonal electric field components at two-time points, showing an excellent match between the experiment and the theory. This study also leads to methods for constructing a tunable DOP source.

Scattering Polarization of 3 μm Water-ice Feature by Large Icy Grains

Abstract Water ice has a strong spectral feature at a wavelength of approximately 3 μm, which plays a vital role in our understanding of the icy universe. In this study, we investigate the scattering polarization of this water-ice feature. The linear polarization degree of light scattered by micron-sized icy grains is known to be enhanced at the ice band; however, the dependence of this polarization enhancement on various grain properties is unclear. We find that the enhanced polarization at the ice band is sensitive to the presence of micron-sized grains as well as their ice abundance. We demonstrate that this enhancement is caused by the high absorbency of the water-ice feature, which attenuates internal scattering and renders the surface reflection dominant over internal scattering. Additionally, we compare our models with polarimetric observations of the low-mass protostar L1551 IRS 5. Our results show that scattering by a maximum grain radius of a few microns with a low water-ice abundance is consistent with observations. Thus, scattering polarization of the water-ice feature is a useful tool for characterizing ice properties in various astronomical environments.

Randomly rotated photoreceptors foil jewel beetle's polarization vision

Jewel beetles don't hide their light under a bushel. Their glimmering metallic wing cases are prized by jewellery designers and adorned the dresses of Victorian gentlewomen. One gown, in London's V&A Museum, is bedecked with more than 5000 shimmering emerald wing cases. Yet, no one was sure how members of the exotic family perceive their own gleaming exoskeletons. Gregor Belušič from the University of Ljubljana, Slovenia, explains that the insects seem to be sensitive to brilliant colours, as they are easily lured into brightly coloured traps. However, thin structures in the exoskeleton surface also polarize the light reflected by their iridescent wing cases and bodies, possibly enhancing the vivid colours in the eyes of their own species. Intrigued by the possibility that their cuticular colours may appear even brighter to the jewel beetles themselves, Belušič and Carmen Quero from the Institute for Advanced Chemistry of Catalonia, Spain, began investigating the appearance and the retina of Coraebus undatus beetles – captured using traps in nearby cork oak woods – to learn more about the image that they project and what they actually see.Opening the black wing coverings to reveal the beetle's iridescent abdomen, Belušič and Andrej Meglič, also from the University of Ljubljana, recorded ultraviolet and blue wavelengths from the back, and green and yellow wavelengths from the underside. Interestingly, when they recorded the light reflected by traps that the beetles were caught in – which are used by foresters in North America to catch other jewel beetle pests – the spectrum of colours matched the blue back of the insect's abdomen reasonably well, but with a strong additional red peak that made the plastic appear purple to human eyes.Belušič and Marko Ilić from The Graduate University for Advanced Studies, Japan, then measured the electrical activity from individual light receptors. They shone light ranging from ultraviolet to red on the insect's eye, while also adjusting the degree of light polarization, to find out which colours and directions of polarization the receptors in the eye were tuned to. Most of the light receptors were tuned to green wavelengths (540 nm), while a few picked up UV and blue light and two receptors were attuned to red light. In addition, most of the photoreceptors were mildly sensitive to light polarization. However, when Belušič, Meglič and Kentaro Arikawa, also from The Graduate University for Advanced Studies in Japan, examined the arrangement of the light receptors, they found that the photoreceptors were randomly rotated relative to each other, essentially cancelling out each other's response to light polarization. Even though the light reflected by the beetle's vividly coloured abdomen is slightly polarized, the insect is apparently incapable of seeing the effects.Jewel beetle eyes seem to see colour well; they are immune to the effects of light polarization, which can brighten and dim specific shades at certain times of day. This allows them to always see the true colour of an object. Belušič says their insensitivity to polarized light also explains why jewel beetle traps work so well. ‘The plastic coloured traps are usually coated with glue, which is shiny and creates a polarized reflection’, he says. The insect's inability to see the effects of polarization means that the traps closely resemble the colour of their own abdomen at all times. ‘The structure and physiology of the retina explain why the sticky traps work at all’, concludes Belušič.

Light polarization dependency existing in the biological photosystem and possible implications for artificial antenna systems.

The processes of biological photosynthesis provide inspiration and valuable lessons for artificial energy collection, transfer, and conversion systems. The extraordinary efficiency of each sequential process of light to biomass conversion originates from the unique architecture and mechanism of photosynthetic proteins. Near 100% quantum efficiency of energy transfer in biological photosystems is achieved by the chlorophyll assemblies in antenna complexes, which also exhibit a significant degree of light polarization. The three-dimensional chiral assembly of chlorophylls is an optimized biological architecture that enables maximum energy transfer efficiency with precisely designed coupling between chlorophylls. In this review, we summarize the key lessons from the photosynthetic processes in biological photosystems, and move our focus to energy transfer mechanisms and the chiral structure of the chlorophyll assembly. Then, we introduce recent approaches and possible implications to realize the biological energy transfer processes on bioinspired scaffold-based artificial antenna systems.

Effect of transparent wood on the polarization degree of light.

We report on the study of polarization properties of light propagating through transparent wood (TW), which is an anisotropically scattering medium, and consider two cases: completely polarized and totally unpolarized light. It was demonstrated that scattered light distribution is affected by the polarization state of incident light. Scattering is the most efficient for light polarized parallel to cellulose fibers. Furthermore, unpolarized light becomes partially polarized (with a polarization degree of 50%) after propagating through the TW. In the case of totally polarized incident light, however, the degree of polarization of transmitted light is decreased, in an extreme case to a few percent, and reveals an unusual angular dependence on the material orientation. The internal hierarchical complex structure of the material, in particular cellulose fibrils organized in lamellae, is believed to be responsible for the change of the light polarization degree. It was demonstrated that the depolarization properties are determined by the angle between the polarization of light and the wood fibers, emphasizing the impact of their internal structure, unique for different wood species.

Three-Dimensional Self-Assembled Columnar Arrays of AlInP Quantum Wires for Polarized Micrometer-Sized Amber Light Emitting Diodes

A three-dimensional ordered and self-organized semiconductor system emitting highly polarized light in the yellow-orange visible range (580–650 nm) is presented, comprising self-assembled in-plane AlInP wires vertically stacked in regularly spaced columns. More than 200 wires per column without detectable defect formation could be stacked. Theoretical simulations and temperature-dependent photoluminescence provided a benchmark to engineer multilayered structures showing internal quantum efficiency at room temperature larger than comparable quantum wells emitting at similar wavelengths. Finally, proof-of-concept light-emitting diodes (LED) showed a high degree of light polarization and lower surface parasitic currents than comparable quantum well LEDs, providing an interesting perspective for high-efficiency polarized yellow-orange light-emitting devices.

Magnetic field modulating in-line fiber polarization modulator based on microfiber and magnetic fluid

We demonstrate an in-line fiber polarization modulator (FPM) which is constructed by immersing a microfiber into magnetic fluid (MF) and modulated with the magnetic field. The polarization modulation principle is based on the magneto-optical dichroism of the MF and the non-circular symmetric distribution of magnetic nanoparticles around the microfiber. Modulations of both the light polarization degree and the polarization direction are realized. The modulation capability, time response, insertion loss, and magnetic field direction dependence of the proposed FPM are studied.

Influence of size, proportion, and absorption coefficient of spherical scatterers on the degree of light polarization and the grain size of speckle pattern.

In this paper, we present the evolution of speckle pattern polarimetric parameters in response to controlled changes in scatterer sizes, proportions, and the absorption coefficient in media. The experimental study was performed on mixtures of polystyrene microspheres with dye in order to ensure biological medium-like properties. The speckle grain sizes and degrees of polarization for linear and circular light were monitored. We observed helicity flipping in the degree of circular polarization for small scatterer proportion around 25%. Furthermore, linear depolarization decreased slightly for media containing more small particles. Good agreement was shown with numerical results computed using a Monte Carlo simulation of polarized light taking into account our experimental configuration. Speckle grain size also evolves with the increase of small scatterers as well as the media absorption coefficient. Such variations of properties are encountered during fruit maturation, in tissues in precancerous stages, and any transformation that causes a modification in particle proportions and absorption coefficient in biological media. The computed parameters proved to be sensitive to these changes.

Characterization of Bacillus thuringiensis parasporal crystals using laser speckle technique: effect of crystal concentration and dimension

In this paper, we report experimental results where laser speckle grain size and degree of light polarization are used to distinguish different sizes of Bacillus thuringiensis spherical crystals and different concentration within fermentation products. Three strains of Bacillus thuringiensis, isolated from the Lebanese soil, are selected. After fermentation, crystals and spores are separated using a technique based on flotation in order to obtain large quantities of relatively pure crystals. Crystals are then embedded in an agarose matrix gel and illuminated by a laser. Speckle patterns are recorded and analyzed. Results show that when crystal concentrations increase in the sample, the values of the degree of light linear polarization and speckle grain size decrease, and the negative values of light circular polarization degree increase. A transition from a Rayleigh scattering regime to a Mie regime is also observed. Furthermore, when the diameter of spherical crystals increases, the normalized value of the light linear polarization degree and the grain size diminish drastically for a given concentration of crystals in the matrix, whereas the normalized value of light circular polarization degree increases. This optical characterization constitutes an unambiguous signature of spherical crystals produced by fermentations of different Bacillus thuringiensis strains and shows that speckle may potentially be used at an industrial scale as a low-cost and noninvasive technique in order to characterize crystal geometry and to evaluate the yield of crystal production within fermentation.

Interband polarized absorption in InP polytypic superlattices

Recent advances in growth techniques have allowed the fabrication of semiconductor nanostructures with mixed wurtzite/zinc-blende crystal phases. Although the optical characterization of these polytypic structures is well reported in the literature, a deeper theoretical understanding of how crystal phase mixing and quantum confinement change the output linear light polarization is still needed. In this paper, we theoretically investigate the mixing effects of wurtzite and zinc-blende phases on the interband absorption and in the degree of light polarization of an InP polytypic superlattice. We use a single 8 × 8 k⋅p Hamiltonian that describes both crystal phases. Quantum confinement is investigated by changing the size of the polytypic unit cell. We also include the optical confinement effect due to the dielectric mismatch between the superlattice and the vaccum and we show it to be necessary to match experimental results. Our calculations for large wurtzite concentrations and small quantum confinement explain the optical trends of recent photoluminescence excitation measurements. Furthermore, we find a high sensitivity to zinc-blende concentrations in the degree of linear polarization. This sensitivity can be reduced by increasing quantum confinement. In conclusion, our theoretical analysis provides an explanation for optical trends in InP polytypic superlattices, and shows that the interplay of crystal phase mixing and quantum confinement is an area worth exploring for light polarization engineering.

Quantum Efficiency Analysis of Near-Ultraviolet Emitting AlGaN and AlInGaN Structures

The quantum efficiency of c-plane AlxGa1-xN and AlxInyGa1-x-yN structures (x = 0.06–0.21, y = 0.015–0.05) emitting in the UV spectral range between 320 and 350 nm was analyzed using temperature-dependent and polarization-resolved photoluminescence measurements. We found increasing bandgap fluctuation and charge carrier localization in case of higher aluminum or higher indium content. Improved suppression of nonradiative recombination was observed only in case of indium incorporation. The light polarization changed from E⊥c to E∥c with increasing aluminum content in AlGaN. It switched back to E⊥c by the incorporation of indium in AlInGaN. Light polarization significantly contributes to the photoluminescence intensity measured from the top, and the degree of light polarization decreases with increasing temperature. Thus, temperature-dependent photoluminescence measured via the c-plane surface was found to depend both on internal quantum efficiency and on extraction efficiency.