Rotation Of Polarization Plane Research Articles

Generation of the CMB cosmic birefringence through axion-like particles, sterile and active neutrinos

The cosmic birefringence (CB) angle refers to the rotation of the linear polarization plane of Cosmic Microwave Background (CMB) radiations when parity-violating theories are considered. We analyzed the Quantum Boltzmann equation for an ensemble of CMB photons interacting with the right-handed sterile neutrino dark matter (DM) and axion-like particles (ALPs) DM in the presence of the scalar metric perturbation. We used the birefringence angle of CMB to study those probable candidates of DM. It is shown that the CB angle contribution of sterile neutrino is much less that two other sources considered here. Next, we combined the results of the cosmic neutrinos’ contribution and the contribution of the ALPs to producing the CMB birefringence and discussed the uncertainty on the parameter space of axions caused by the share of CMB-cosmic neutrino interaction in generating this effect. Finally, we plotted the EB power spectrum of the CMB and showed that this spectrum behaves differently in the presence of cosmic neutrinos and ALPs interactions in small l. Hence, future observed data for CEBl,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C^{l}_{EB},$$\\end{document} will help us to distinguish the CB angle value due to the various sources of its production.

Few-layer bifunctional metasurfaces enabling asymmetric and symmetric polarization-plane rotation at the subwavelength scale

We introduce and numerically validate the concept of few-layer bifunctional metasurfaces comprising two arrays of quasiplanar subwavelength resonators and a middle grid (array of rectangular holes) that offer both symmetric and asymmetric transmissions connected, respectively, with symmetric and asymmetric polarization-plane rotation functionalities. The proposed structures are thinner than λ/7\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda /7$$\\end{document} and free of diffractions. Usually, the structure’s symmetry or asymmetry, i.e. unbroken or broken spatial inversion symmetries, are considered for metasurfaces as prerequisites of the capability of symmetric or asymmetric conversion of linearly polarized waves, respectively. Due to the achieved adjustment of the resonances enabling the rotation of the polarization plane simultaneously for both orthogonal polarizations of the incident wave, the symmetric polarization-plane rotation functionality can be obtained within one subwavelength band, whereas the asymmetric polarization-plane rotation functionality associated with the asymmetric transmission is obtained within another subwavelength band. This combination of the functionalities in one subdiffraction structure is possible due to the optimal choice of the grid parameters, since they may strongly affect the coupling between the two resonator arrays. Although normal incidence is required for the targeted bifunctionality, the variations of the incidence angle can also be exploited for the enrichment of the overall functional capability. Variations of the polarization angle give another important degree of freedom. The connection between the polarization-angle dependence of cross-polarized transmission and capability of symmetric and asymmetric polarization-plane rotation functionalities is highlighted. The feasible designs of the bifunctional metasurfaces are discussed.

Development of manufacturing technology of polarization parabolic antenna reflectors for antennas of millimeter wave band

Structurally antenna with rotation of the polarization plane consists of three main elements: an irradiator, a parabolic transreflector and a flat twist-reflector. A common problem for such antennas is complexity of the manufacture of the main element – parabolic transreflector. The purpose of the article is search for unreinforced foiled material, research the possibility of manufacturing parabolic transreflector by the photochemical method of making printed boards, as well as forming blanks for parabolic forming them. The article considers a new method of manufacturing of a parabolic transreflector for an antenna made of foil-fluoroplastic with a rotation of polarization plane. The technology of forming conductors with a width of 75 microns with a step of 225 microns by the photochemical method (according to the technology of manufacturing printed circuit boards) with subsequent molding of the workpiece to obtain a given parabolic form, has been developed. The main technological operations of manufacturing a parabolic transreflector have been described. The proposed solutions indicate the prospects of the developed technology manufacturing of polarization parabolic antenna reflectors for millimeter wave antennas.

УСУНЕННЯ ЗАВАД У ДИНАМІЧНИХ СПЕКТРАХ ЗА НАЯВНОСТІ ПОТУЖНОГО СИГНАЛУ ЧАСТИНА 1. ПОТУЖНІ ШИРОКОСМУГОВІ ІМПУЛЬСИ ТА ЛІНІЙНО ЧАСТОТНО-МОДУЛЬОВАНІ ЗАВАДИ

Subject and Purpose. The writers aim at developing and testing a new method of interference mitigation, proceeding from the example of radio emissions from Jupiter. Its effectiveness is compared with the results of other workers, equally relating to the case of a significant overlapping, within the time-frequency window under analysis, of the areas occupied by the useful signal and the interference. Methods and Methodology. The analysis has revealed several fundamental limitations associated with the use of standard statis- tical methods for identifying sources of interference. A new approach is proposed that allows separating useful signals from inter- ference in the time-frequency plane. It is based on the idea of transferring the statistical analysis from the space of signal amplitudes to such of linear patterns which are formed by maximal readings while the spectrograms are being scanned in time, frequency or otherwise. Results. Methods of statistical data processing have been suggested which allow analysis of signals of a variety of power lev- els against the background of interference of comparable intensity. This enables a detailed analysis of the time-frequency patterns demonstrated by signals with a broad range of parameter variations. The algorithms developed demonstrate stability against changes in the interference background conditions that may be caused either by human activity or by natural factors, such as, e.g. ionospheric perturbations, changes in the frontend frequency response of a receiver resulting from a changed antenna beam orientation, or else from Faraday’s polarization plane rotation in the radio emission being received. Conclusions. The necessity of creating new interference mitigation techniques is stipulated both by worsening of the general level of interference at radio frequencies, and by the growth of complexity in the sporadically emerging time-frequency patterns that result from the improved time and frequency resolutions in the course of signal reception. A significant progress has been achieved, owing exclusively to the fundamental modifications of the signal processing algorithms that are based on varying the direction of analysis in the time-frequency plane.

ВЛАСНІ КОЛИВАННЯ В ПЛАНАРНО-КІРАЛЬНИХ ДВОШАРОВИХ ОБ’ЄКТАХ ПОРОДЖУЮТЬ ШТУЧНУ ОПТИЧНУ АКТИВНІСТЬ

Subject and Purpose. The research focuses on how the resonance frequencies, the Q-factor of resonances, and the polarization plane rotation ability are influenced by the topology of individual components of a planar-chiral double-layer object consisting of a pair of con- jugated irises having rectangular slots and accommodated in a circular waveguide. Methods and Methodology. All the numerical results are obtained by the mode-matching technique (MMT) and the transverse reso- nance method on the basis of our own proprietary MWD-03 software package. Results. By the waveguide example, it has been shown that the internal structure of individual components and dihedral symmetry of the conjugated bilayer allow all the conclusions of the spectral theory (theory of eigen-oscillations) to be carried over to all the objects of the type. On the other hand, these objects behave as symmetric two-port waveguide components with conventionally "symmetric" and "antisymmetric" eigen-oscillations. The mutual coupling of these eigen-oscillations depends on the bilayer parameters. Where the frequen- cies of these eigen-oscillations are close enough, the polarization plane rotation and the transmission bandwidth reach their highest. It has been demonstrated that as a slot number increases, the resonance frequency decreases. The theoretical results have been confirmed by the measurements at the X range of frequencies for pairs of conjugated irises with various numbers of rectangular slots. Conclusions. A pair of conjugated chiral irises can rotate the polarization plane. The iris topology, iris spacing, and the mutual ro- tation angle alter resonance frequencies. The resonance frequencies can be reduced by increasing the rectangular slot length and/or slot number. Even though they have not longitudinal symmetry, such objects have properties of two-port waveguide components. In particular, the phase shift of their reflection and transmission coefficients is modulo 90. Besides, a possibility exists to divide eigen-oscillations into conventionally "symmetric" and "antisymmetric" based on the proximity of their fields to those whose type of symmetry is known before- hand. This makes it possible to approximate the reflection and transmission coefficients through corresponding eigenfrequencies.

Modeling reversals of galactic magnetic fields at large distances from centers of milky-way-like galaxies using computations on GPUs

Nowadays it is strongly believed that in a large number of spiral galaxies there are regular magnetic fields. Their existence is proved by measurements of the Faraday rotation of polarization plane of electromagnetic waves which are received on modern radio telescopes. The theoretical description of magnetic fields generation is connected with the mean field dynamo mechanism. It is based on joint action of the ?-effect and differential rotation. At the first stage of evolution, magnetic fields enlarge exponentially with the growth rate described by the largest eigenvalue of the corresponding differential operator. If the field becomes comparable with the equipartition value, the nonlinear terms become more important, and they are connected with saturation of the field growth. The non-linear system of equations has several stationary points, and some of them are stable. According to the contrast structures theory for a quite small turbulent viscosity and some initial conditions, in different regions there will be magnetic fields of opposite directions, and they will be divided by narrow transition layers. Such features, for example, characterize the magnetic field of the Milky Way. Most of the existing works describe reversals for quite moderate distances from the galaxy center. However, it was shown previously that the magnetic field can principally be generated also in outer parts of galaxies, which are situated at distances of more than 10 kpc from the rotation axis. It is interesting to describe the appearance of reversals in such parts of galaxies. In this work we have studied the dynamo action in outer parts of the Milky-Way-like galaxies. It is shown that it is possible to generate opposite magnetic fields there. We have used random initial conditions to obtain spatial reversals. Because of a large volume of computations, they were carried out by using graphics processing units (GPUs).

Polarization control and enhanced magnetic field sensitivity utilizing surface plasmon polaritons-assisted dual-V-type four-level system

We propose a kind of surface plasmon polaritons (SPPs)-assisted dual-V-type four-level composite system used for high-sensitivity weak magnetic field measurement. The SPPs are excited by a D-shaped photonic crystal fiber (PCF) deposited with gold nanowires, and are interacted with the above quantum emitter from the rubidium atomic vapor. In the presence of the external magnetic field, Faraday rotation symmetry is broken due to Zeeman effect, resulting in the polarization plane rotation when a linearly polarized probe field goes through the above quantum emitter. With the help of the coupled field and SPPs, Faraday magneto-optical rotation (MOR) are effectively regulated. The Rabi frequency of the coupled field (Ω c ), quantum interference degree (q), and phase difference (φ) between the applied fields show strong dependence on the MOR angle and magnetic field measurement sensitivity. The simulated results reveal that the maximum MOR angle and magnetic field sensitivity both damp with Ω c expanding and q reducing. The maximum dichroism-independent MOR angle of 89.97° is realized for φ = 0° (180°), and the magnetic field sensitivity of 10.88°/Oe is obtained in the sweeping range of −8.88–8.88 Oe for q = 0.99, being 2.66°/Oe higher than that in the absence of SPPs (q = 0). Most importantly, the output probe field with different polarization forms can be realized by adjusting the φ value. Hence, the proposed device exhibits the potential in the fields of weak magnetic field measurement and polarization control.

Probing axions through tomography of anisotropic cosmic birefringence

Cosmic birefringence is the in-vacuo rotation of the linear polarization plane experienced by photons of the Cosmic Microwave Background (CMB) radiation when theoretically well-motivated parity-violating extensions of Maxwell electromagnetism are considered. If the angle parametrizing such a rotation is dependent on the photon's direction, then this phenomenon is called Anisotropic Cosmic Birefringence (ACB). In this paper, we perform for the first time a tomographic treatment of the ACB, by considering photons emitted both at the recombination and reionization epoch. This allows one to extract additional and complementary information about the physical source of cosmic birefringence with respect to the isotropic case. We focus here on the case of an axion-like field χ, whose coupling with the electromagnetic sector induces such a phenomenon, by using an analytical and numerical approach (which involves a modification of the CLASS code). We find that the anisotropic component of cosmic birefringence exhibits a peculiar behavior: an increase of the axion mass implies an enhancement of the anisotropic amplitude, allowing to probe a wider range of masses with respect to the purely isotropic case. Moreover, we show that at large angular scales, the interplay between the reionization and recombination contributions to ACB is sensitive to the axion mass, so that at sufficiently low multipoles, for sufficiently light masses, the reionization contribution overtakes the recombination one, making the tomographic approach to cosmic birefringence a promising tool for investigating the properties of this axion-like field.

Plasma local diagnostics by polarimetric method

We study the polarization plane rotation of weak probe signal in the field of strong electromagnetic waves in the presence of an external magnetic field of plasma, the polarization plane stimulated rotation angle of the probe signal in the intense laser field and in plasma is calculated. The estimates of the residual gas local density in a cesium plasma based on the effects of Faraday, Cotton–Mouton and stimulated rotation of the probe signal in the intense laser field have been found. It is shown, that the rotation angle in the cesium plasma medium has a complex structure.

Broadband Spintronic Terahertz Source with Peak Electric Fields Exceeding 1.5 MV/cm

Spintronic terahertz emitters (STEs) are desirable broadband terahertz sources, but their limited signal strength has hindered practical application. By optimizing the photonic and thermal environment, the authors present an STE that could overcome this obstacle. Benchmarking against the state-of-the-art terahertz emitters based on optical rectification, this STE delivers strong terahertz pulses with comparable peak electric field and fluence, and offers additional features such as broadband radiation, easy alignment, and rotation of the terahertz polarization plane without power loss. This work will open up a promising pathway to nonlinear terahertz spectroscopy with spintronic sources.

CHANCES OF WRONG INFORMATION RECEPTION DURING ELECTROMAGNETIC INFLUENCE UPON OPTICAL CABLE

Long-distance communication lines are optical fiber lines in most cases now. This moment PM QPSK system (polarization-division multiplex with quadrature phase shift keying) appear. Polarization-division multiplex uses a fact that the optical signal can propagate as two orthogonal polarized modes that allows to use the modes independently and makes it possible to double carrier capacity (together with already other used multiplex system). Two orthogonal waves using in the same fiber can cause problems during lightning discharges close by cable line. Under influence of external cross electrical field (or longitudinal magnetic) the polarizations plane of lights wave can turns on angle, which depends on field value, light path length upon field action and fiber sensitivity. During the influence of external electromagnetic field issue a part of one polarization signal can pass to other orthogonal plane and it will perceive wrongly. The Wavelength Division Multiplexing (WDM) systems development with increasing number of carriers brought to transmission in the same transparency window some tens or hundreds waves. They are shifted relative to each other for some parts of nanometers during the lightning stroke. Therefore the polarization plane rotation will be different for each wave (other conditions being equal): the short waves rotated greater than the long waves. On input of optical amplifier there will be packet of waves with different polarizations, and it can produce problems to filters, optical insulators and amplifiers, to Raman amplifiers specially, which are sensitive to polarization. It is known that short and long waves are moving with different velocity as refraction index depends upon wave length. Usually the rotation angle quantity is small if resistivity of earth near cable is not heavy and if equipment does not contain sensitive to PMD (Polarization Modes Dispersion). This phenomenon passes usually unnoticed. But sometimes with strong thunderstorm and lightning stroke at a short distance the polarization plane rotation can exceed 45º or even 90º. Hereby, it is possible the complex electrical and magnetic fields influence during thunderstorm on orthogonal polarization using, that can lead to additional component appearance in orthogonal axes and to signal reception error. Error level for year is estimated.

Practice of the Visual Determination of the Direction of the Rotation of the Light Polarization Plane in Gyrotropic Uniaxial Single Crystals

Practice of the Visual Determination of the Direction of the Rotation of the Light Polarization Plane in Gyrotropic Uniaxial Single Crystals

Practice of the visual determination of the direction of light polarization plane rotation in the gyrotropic uniaxial single crystals

When studying and applying crystals of the middle category, it is necessary to take into account the manifestations of anisotropy of their properties, in particular, optical anisotropy. One of the manifestations of optical anisotropy is the rotation of the polarization plane (gyrotropy effect), which is observed in the direction of the optical axis of such crystals. The plane of polarization of light can rotate clockwise and counterclockwise. To determine the direction of rotation of the polarization plane, simple visual methods can be used based on studies of samples in converging polarized light – observations of conoscopic figures. In general, the type of conoscopic figures depends on the relative position of the polarizers, the wavelength of light in the system, the cut of the single crystal perpendicular to which the light propagates, the thickness of the sample and the birefringence. The direction of rotation of the polarization plane can be determined by еру change of the type of conoscopic figure of a sample of a gyrotropic crystal cut perpendicular to the optical axis: change of the central spot color during the analyzer rotation; the extinction of the central spot when observing a conoscopic figure using light filters; the direction of movement of the rings in monochromatic light; observation of Airy patterns. According to the experience of working in our laboratory “Single crystals and Stocke on their Base”, the simplest, most operational and unambiguous visual method for determining the direction of rotation of the polarization plane is the observation of Airy figures. A conoscopic pattern in the form of Airy figures (a four-way spiral) occurs when observing in converging polarized light a combination of two superimposed samples of gyrotropic crystals cut perpendicular to the optical axis, rotating the plane of polarization of light in opposite directions. To use this method, a well-known sample of a gyrotropic crystal cut perpendicular to the optical axis is required.

Diffused magnetic transitions in NiFe2O4/SrTiO3(0 0 1) epitaxial heterostructures

Magnetization reversal in as-grown and annealed NiFe2O4 / SrTiO3(001) epitaxial heterostructures, prepared by laser molecular beam epitaxy (LMBE), was studied using magneto-optical technique in geometry of polar (PMOKE) and longitidual (LMOKE) Kerr effect. It was found that the hysteresis loops of polarization plane rotation and ellipticity measured in LMOKE geometry are combinations of symmetric (even in magnetic field) SPart and antisymmetric (odd in magnetic field) AsPart parts, caused by quadratic (QMOKE ∼ MiMj) and linear (LMOKE ∼ Mi) in magnetization M contributions, correspondingly. The angular dependences of SPart demonstrate in-plane biaxial magnetic anisotropy (BMA) and show that magnetization reversal in as-grown structures occurs by one jump (1j) process, in contrast to the annealed structures, in which two jumps (2j) process takes place when the deviation of magnetic field from the hard axis is less than ∼20°. Analysis within the framework of the Stoner-Wohlfarth (SW) model with account of domain mechanism of magnetization jumps shows that the first jump occurs due to formation and movement of domain walls. Second jump is remarkably diffused, that is associated with the dispersion of the biaxial anisotropy field Ha and misorientations of the magnetic easy axes in different regions of the film. Narrow and strong FMR lines are observed in the most perfect structures in which the diffusion of the second jump is small. The degree of second jump diffusion can be used to assess the structural perfection of the films.

Polarimetric method of plasma diagnostics

The polarization plane rotation angle of a probe signal in plasma is calculated. The estimates of the residual gas average density and the average magnitude of the magnetic field in a cesium plasma based on the effects of Faraday and Cotton–Mouton in a probe laser field have been found. It is shown that the polarization plane rotation angle depends on resonance detuning of the incident laser wave and transition frequency of medium atoms, magnetic field strength and matrix element.

Enhanced magneto-optical rotation of probe field in thermal medium via spontaneous generated coherence

A four-level double lambda closed atomic configuration is considered to study the polarization plane rotation of the probe beam through cold as well as thermal Rb^{87} atomic medium by varying the spontaneously generated coherence (SGC). Magnetic field and strong coupling field are applied to the atomic configuration. The light-matter interaction leads to enhanced the magneto-optical rotation. The intensity of the applied fields plays promising role in the generation and enhancement of birefringence. It ultimately enhances the polarization plane rotation of the probe beam in the Doppler medium. In the presence of both SGC and Doppler broadening effects, the optical rotation and transmission of the weak light beam are modified and controlled as well, which have potential applications in magnetometery and laser frequency stabilization.

GYROTROPY FEATURES OF AN IMPERFECT OPTICALLY ACTIVE 1D PHOTONIC ORIENTATIONALLY DISORDERED CRYSTAL

The paper is devoted to gyrotropic characteristics of a non-ideal 1D photonic crystal with an arbitrary number of sublattices (of which one is the optically active potassium dithionate K2S2O6) and to their variation due to a random layer substitution in the K2S2O6 sublattice by modeling impurity layers of an orientationally disordered molecular crystal. We adopt a microscopic approach to study the specific (per unit volume) light polarization plane rotation angle in the exciton spectrum region and perform the numerical calculation of the superlattice optical activity dependence on concentrations of impurity layers and of point-like defects (orientationally disordered molecules) which the latter contain.

Efficient asymmetric transmission for wide incidence angles using chiral s plit‐ring‐resonators

In this article, a chiral metasurface is proposed for controlling the linear polarization over broadband which consists of simple circular split-ring-resonator based unit cells on both sides of ultrathin (0.05λ at the operating frequency of 20 GHz) substrate. Across the large operating band (19.4–22.7 GHz), the structure is highly efficient with transmission efficiency greater than 0.94 and asymmetric transmission magnitude more than 0.8. Moreover, the structure exhibits stable response up to 45°, which is desirable for many K-band applications in radar and small satellite communication systems. The proposed metasurface acquires direction-dependent propagation with 90° linear polarization plane rotation, as depicted by simulated and experimental results. Furthermore, the structure is insensitive to circular polarized propagation within the operating band.

Effect of the phase switching of the optical FID in magnetic field

This work demonstrates the possibility of switching the phase of optical free induction decay (FID) in time-domain experiments. This possibility arises in experiments with paramagnetic molecules (free radicals) in a magnetic field. Changing the direction of the magnetic field alters the direction of rotation of the FID polarization plane and inverts the phase of one of the components of FID. This effect will be useful for heterodyne detection of the optical FID of the free radicals in the terahertz region.

Cosmic birefrigence: cross-spectra and cross-bispectra with CMB anisotropies

Parity-violating extensions of Maxwell electromagnetism induce a rotation of the linear polarization plane of photons during propagation. This effect, known as cosmic birefringence, impacts on the Cosmic Microwave Background (CMB) observations producing a mixing of E and B polarization modes which is otherwise null in the standard scenario. Such an effect is naturally parametrized by a rotation angle which can be written as the sum of an isotropic component α 0 and an anisotropic one δα(n̂). In this paper we compute angular power spectra and bispectra involving δα and the CMB temperature and polarization maps. In particular, contrarily to what happens for the cross-spectra, we show that even in absence of primordial cross-correlations between the anisotropic birefringence angle and the CMB maps, there exist non-vanishing three-point correlation functions carrying signatures of parity-breaking physics. Furthermore, we find that such angular bispectra still survive in a regime of purely anisotropic cosmic birefringence, which corresponds to the conservative case of having α o = 0. These bispectra represent an additional observable aimed at studying cosmic birefringence and its parity-violating nature beyond power spectrum analyses. They provide also a way to perform consistency checks for specific models of cosmic birefringence. Moreover, we estimate that among all the possible birefringent bispectra,〈δαTB〉and〈δαEB〉are the ones which contain the largest signal-to-noise ratio. Once the cosmic birefringence signal is taken to be at the level of current constraints, we show that these bispectra are within reach of future CMB experiments, as LiteBIRD.