Rotation Of Polarization Plane Research Articles

Simulation of polarized optical radiation transport in time and frequency representations

Monte Carlo simulation of backward scattering of polarized optical radiation has been performed in the time and frequency representations based on the description of radiation transport in terms of the Bethe–Salpeter equation. The histograms of an ultrashort pulse of linearly or circularly polarized radiation have been calculated in the time representation; it is found that for distances between the source and detector on the order of the transport length, the histograms exhibit a strong dependence on the polarization type; in the case of circular polarization, the direction of the polarization plane rotation changes upon an increase in the scattering anisotropy.

Компактные вращатели плоскости поляризации на заданный угол в квадратном волноводе

Компактные вращатели плоскости поляризации на заданный угол в квадратном волноводе

Polarization Response Manipulation for Compound Circular Hole Fishnet Metamaterial

Two compound circular hole screens, which possess rotation symmetry and are conjugately stacked in such a way that the whole structure has ${D_4}$ dihedral symmetry, are considered to rotate polarization plane of a normally incident wave. The eigenmodes responsible for the polarization plane rotation are analytically investigated on the base of the representation theory of groups and illustrated by numerical results.

Dependence of laser radiation intensity on the elastic deformation of a revolving optical disk with a reflective coating

The physical mechanism of alteration of intensity of linearly polarized monochromatic electromagnetic radiation with λ = 630 nm in a revolving dielectric disk with a mirror coating is examined. The effect is induced by elastic deformation due to the revolution and by thermoelastic deformation of the optically transparent disk. These deformations result in birefringence, the polarization plane rotation, and a 30–40% change in the intensity of reflected radiation.

Minicharged particles search by strong laser pulse-induced vacuum polarization effects

Laser-based searches of the yet unobserved vacuum birefringence might be sensitive for very light hypothetical particles carrying a tiny fraction of the electron charge. We show that, with the help of contemporary techniques, polarimetric investigations driven by an optical laser pulse of moderate intensity might allow for excluding regions of the parameter space of these particle candidates which have not been discarded so far by laboratory measurement data. Particular attention is paid to the role of a Gaussian wave profile. It is argued that, at energy regimes in which the vacuum becomes dichroic due to these minicharges, the transmission probability of a probe beam through an analyzer set crossed to the initial polarization direction will depend on both the induced ellipticity as well as the rotation of the initial polarization plane. The weak and strong field regimes, relative to the attributes of these minicharged particles, and the relevance of the polarization of the strong field are investigated.

The influence of magnetic field on the echo-like free induction decay in NO2

The effect of magnetic field on the free induction in NO2 was studied. The experiments were performed using the Free Electron Laser in the terahertz frequency domain. A magnetic field affects the free induction decay in two ways. First, it reduces the integral intensity of the free induction radiation. Second, application of the magnetic field results in the rotation of the polarization of the free induction radiation. Both effects were observed experimentally as well as simulated numerically using a theoretical model. A large angle of the polarization plane rotation was observed upon application of magnetic field of 120G.

Faraday effect on the Rb D 1 line in a cell with a thickness of half the wavelength of light

The rotation of the radiation polarization plane in a longitudinal magnetic field (Faraday effect) on the D1 line in atomic Rb vapor has been studied with the use of a nanocell with the thickness L varying in the range of 100–900 nm. It has been shown that an important parameter is the ratio L/λ, where λ = 795 nm is the wavelength of laser radiation resonant with the D1 line. The best parameters of the signal of rotation of the radiation polarization plane have been obtained at the thickness L = λ/2 = 397.5 nm. The fabricated nanocell had a large region with such a thickness. The spectral width of the signal reached at the thickness L = 397.5 nm is approximately 30 MHz, which is much smaller than the spectral width (≈ 500 MHz) reached with ordinary cells with a thickness in the range of 1–100 mm. The parameters of the Faraday rotation signal have been studied as functions of the temperature of the nanocell, the laser power, and the magnetic field strength. The signal has been reliably detected at the laser power PL ≥ 1 μW, magnetic field strength B ≥ 0.5 G, and the temperature of the nanocell T ≥ 100°C. It has been shown that the maximum rotation angle of the polarization plane in the longitudinal magnetic field is reached on the Fg = 3 → Fe = 2 transition of the 85Rb atom. The spectral profile of the Faraday rotation signal has a specific shape with a sharp peak, which promotes its applications. In particular, Rb atomic transitions in high magnetic fields about 1000 G are split into a large number of components, which are completely spectrally resolved and allow the study of the behavior of an individual transition.

Determination of gyrotropic characteristics in tetragonal zinc and cadmium diphosphide crystals

We have reported on the results of an investigation of the gyrotropic properties of zinc and cadmium diphosphide tetragonal crystals. It has been found that the regime of obtaining crystals affects the specific rotation of the light polarization plane in a cadmium diphosphide. It has been shown that the dispersion of optical activity in the polarizer–optically active crystal–analyzer system leads to oscillations in the transmission spectra under certain conditions. The peculiar optical properties of gyrotropic crystals placed in between two polarizers can be used to construct optical filters.

Coherent spin dynamics of carriers in ferromagnetic semiconductor heterostructures with an Mn δ layer

The coherent spin dynamics of carriers in the heterostructures that contain an InGaAs/GaAs quantum well (QW) and an Mn δ layer, which are separated by a narrow GaAs spacer 2–10 nm thick, is comprehensively studied by the magnetooptical Kerr effect method at a picosecond time resolution. The exchange interaction of photoexcited electrons in QW with the ferromagnetic Mn δ layer manifests itself in magnetic-field and temperature dependences of the Larmor precession frequency of electron spins and is found to be very weak (several microelectron volts). Two nonoscillating components related to holes exist apart from an electron contribution to the Kerr signal of polarization plane rotation. At the initial stage, a fast relaxation process, which corresponds to the spin relaxation of free photoexcited holes, is detected in the structures with a wide spacer. The second component is caused by the further spin dephasing of energyrelaxed holes, which are localized at strong QW potential fluctuations in the structures under study. The decay of all contributions to the Kerr signal in time increases substantially when the spacer thickness decreases, which correlates with the enhancement of nonradiative recombination in QW.

RoboPol: do optical polarization rotations occur in all blazars?

We present a new set of optical polarization plane rotations in blazars, observed during the third year of operation of RoboPol. The entire set of rotation events discovered during three years of observations is analysed with the aim of determining whether these events are inherent in all blazars. It is found that the frequency of the polarization plane rotations varies widely among blazars. This variation cannot be explained either by a difference in the relativistic boosting or by selection effects caused by a difference in the average fractional polarization. We conclude that the rotations are characteristic of a subset of blazars and that they occur as a consequence of their intrinsic properties.

X-ray natural birefringence in reflection from graphene

The existence of natural birefringence in x-ray reflection on graphene is demonstrated at energies spanning the carbon $1s$ absorption edge. This new x-ray effect has been discovered with precision measurements of the polarization-plane rotation and the polarization-ellipticity changes that occur upon reflection of linearly polarized synchrotron radiation on monolayer graphene. Extraordinarily large polarization-plane rotations of up to ${30}^{\ensuremath{\circ}}$, accompanied by a change from linearly to circularly polarized radiation have been measured for graphene on copper. Graphene on single crystalline cobalt, grown on tungsten, exhibits rotation values of up to ${17}^{\ensuremath{\circ}}$. Both graphene systems show resonantly enhanced effects at the ${\ensuremath{\pi}}^{*}$ and ${\ensuremath{\sigma}}^{*}$ energies. The results are referenced against those obtained for polycrystalline carbon and highly oriented pyrolytic graphite (HOPG), respectively. As expected, polycrystalline carbon shows negligible rotation, whereas a huge maximum rotation of ${140}^{\ensuremath{\circ}}$ has been observed for HOPG that may be considered a graphene multilayer system. HOPG is found to exhibit such large rotation values over a broad energy range, even well beyond the ${\ensuremath{\pi}}^{*}$ resonance energy due to the contributions of numerous graphene layers. To explain the origin of the observed natural birefringence of graphene, the Stokes parameters as well as the x-ray natural linear dichroism in reflection have been determined. It is shown that the birefringence directly results from the optical anisotropy related to the orthogonal alignment of ${\ensuremath{\pi}}^{*}$ and ${\ensuremath{\sigma}}^{*}$ bonds in the graphene layer. Our polarization analysis reveals a strong bonding of graphene on Co with a reduced ${\ensuremath{\sigma}}^{*}$ excitation energy and a strong tilt of $50%$ of the ${p}_{z}$ orbitals towards diagonal orientation. In contrast, graphene on Cu is weakly bound with an orthogonal orientation of the ${p}_{z}$ orbitals. Exhibiting such a large natural birefringence that can be controlled through substrate choice, and because of excellent heat conductivity, graphene materials have a potential to be used as tunable x-ray phase shifting $\ensuremath{\lambda}/4$ or $\ensuremath{\lambda}/2$ plates in the design of future high-intensity light sources.

Rotation of the Polarization Plane of Light Via Use of the DNA-Based Structures for Innovative Medical Devices

It is well known that in the biomedicine the people use sugar meter instruments to test the level of the sugar in the blood. The physical effect activated in these types of the devices is coincided with the mechanism of the rotation of the polarization plane of the light. Generally, in order to operate with an active media responsible for the rotation of the light polarization plane one can use classical ~10% sugar-water solution. In the current paper the innovative approach has been shown to apply the DNA-based structures in order to activate the optical effect regarding the rotation of the polarization plane of the light.

RoboPol: optical polarization-plane rotations and flaring activity in blazars

We present measurements of rotations of the optical polarization of blazars during the second year of operation of RoboPol, a monitoring programme of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events, and we analyse the large set of rotation events discovered in two years of observation. We investigate patterns of variability in the polarization parameters and total flux density during the rotation events and compare them to the behaviour in a non-rotating state. We have searched for possible correlations between average parameters of the polarization-plane rotations and average parameters of polarization, with the following results: (1) there is no statistical association of the rotations with contemporaneous optical flares; (2) the average fractional polarization during the rotations tends to be lower than that in a non-rotating state; (3) the average fractional polarization during rotations is correlated with the rotation rate of the polarization plane in the jet rest frame; (4) it is likely that distributions of amplitudes and durations of the rotations have physical upper bounds, so arbitrarily long rotations are not realised in nature.

Achromatic polarization rotator imprinted by ultrafast laser nanostructuring in glass

We demonstrate achromatic polarization rotators implemented by femtosecond laser assisted nanostructuring of silica glass. The rotation of polarization plane results from the chiral arrangement of optical axis embedded in the multi-layered stack of birefringent layers. In our experiments, we achieved rotation of 46.0 ± 0.6° and 93 ± 6° in the broad spectral range of 600–1600 nm, which can be extended even further up to 5 μm. These silica birefringent optical components exhibit advantages over liquid crystal polarizing devices or broadband crystalline waveplates, including large acceptance angle, high thermal stability, and high damage threshold.

Features of faraday rotation in cs atomic vapor in a cell thinner than the wavelength of light

Features of the effect of Faraday rotation (the rotation of the radiation polarization plane) in a magnetic field of the D 1 line in Cs atomic vapor in a nanocell with the thickness L varying in the range of 80–900 nm have been analyzed. The key parameter is the ratio L/λ, where λ = 895 nm is the wavelength of laser radiation resonant with the D 1 line. The comparison of the parameters for two selected thicknesses L = λ and λ/2 has revealed an unusual behavior of the Faraday rotation signal: the spectrum of the Faraday rotation signal at L = λ/2 = 448 nm is several times narrower than the spectrum of the signal at L = λ, whereas its amplitude is larger by a factor of about 3. These differences become more dramatic with an increase in the power of the laser: the amplitude of the Faraday rotation signal at L = λ/2 increases, whereas the amplitude of the signal at L = λ almost vanishes. Such dependences on L are absent in centimeter-length cells. They are inherent only in nanocells. In spite of a small thickness, L = 448 nm, the Faraday rotation signal is certainly detected at magnetic fields ≥0.4 G, which ensures its application. At thicknesses L < 150 nm, the Faraday rotation signal exhibits “redshift,” which is manifestation of the van der Waals effect. The developed theoretical model describes the experiment well.

Experimental investigation of polarization plane rotation of light in nanoparticle-enriched cholesteric liquid crystal cell with an anisotropic defect layer

The possibility of defect induction controlled by external electric field in nanoparticle-enriched cholesteric liquid-crystalline cells with selective reflection in visible range of light and control the rotation of polarization plane of light by induced defect was experimentally demonstrated. The main result of the experiment is the fact that the rotation of the polarization plane of light occurs at lower voltages when the cholesteric liquid crystal is enriched by nanoparticles. A new configuration of liquid crystal device that performs as a tunable linear polarizer for both polarized and unpolarized lights is presented.

Evolution of the polarization of the He-Ne-laser radiation in a rotating insulator

The propagation of the polarized coherent radiation of a He-Ne laser in a rotating insulator is experimentally studied. The reversible transient process of the rotation of the polarization plane and variations in the degree of ellipticity, depolarization, and deflection of the laser beam with a relaxation time of τ = 102–103 s are observed at an insulator rotation frequency of f = 2–250 Hz.

Peculiarities of the modulation of optical radiation during magnetomechanical oscillations in bilayer composite structures

Peculiarities of the modulation of optical radiation during the excitation of magnetomechanical oscillations in a composite structure consisting of magneto-optical crystal and magneto-passive layer have been studied. Analytical expressions for the amplitude- and phase-frequency characteristics of a magneto-optical light modulator based on the Faraday effect for a low-frequency mode under conditions of magnetomechanical resonance were obtained. The results of theoretical and experimental investigations of a modulator in the form of bilayer composite structure consisting of yttrium iron garnet and quartz glass were presented. The relative change of the amplitude of polarization plane rotation in the region of resonance frequencies at the level of 25% and the phase delay of 22° were obtained experimentally.

Natural oscillations providing 90° polarization plane rotation by planar chiral double-slot irises

The common origin of the “enhanced transmission” through small holes and polarization plane rotation (“optical activity”) resonances peculiar for a pair of conjugated planar chiral irises is demonstrated. The eigenoscillation spectra are studied extensively from the “aperture” eigenoscillations of plane junctions responsible for the “enhanced transmission” through the planar chiral iris up to the eigenoscillations of “dihedral” symmetry formed in a composite double slot planar chiral iris. Their excitation results in polarization plane rotation of the dominant mode in a square waveguide. A new compact unit for TE 01 to TE 10 conversion operating within 5–10% frequency band is proposed and validated experimentally. All conclusions are valid for various types of metasurfaces based on the “fish-net” gratings.

Two wavelength Mueller matrix reconstruction of blood plasma films polycrystalline structure in diagnostics of breast cancer.

The model of a Mueller matrix description of mechanisms of optical anisotropy typical for polycrystalline films of blood plasma--optical activity, birefringence, as well as linear and circular dichroism--is suggested. On this basis, the algorithms of reconstruction of parameters distribution (polarization plane rotations, phase shifts, coefficients of linear and circular dichroism) of the indicated types of anisotropy were found for different spectrally selective ranges. Within the statistical analysis of such distributions, the objective criteria of differentiation of films of blood plasma taken from healthy women and breast cancer patients were determined. From the point of view of probative medicine, the operational characteristics (sensitivity, specificity and accuracy) of the method of Mueller matrix reconstruction of optical anisotropy parameters were found, and its efficiency in diagnostics of breast cancer was demonstrated.