Rotation Of Light Polarization Plane Research Articles

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.

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.

Evaluation of the P, T -odd Faraday effect in Xe and Hg atoms

Accurate evaluation of the $\mathcal{P}$,$\mathcal{T}$-odd Faraday effect (rotation of the polarization plane for the light propagating through a medium in presence of an external electric field) is presented. This effect can arise only due to the $\mathcal{P}$,$\mathcal{T}$-odd interactions and is different from the ordinary Faraday effect, i.e. the light polarization plane rotation in an external magnetic field. The rotation angle is evaluated for the ICAS (intracavity absorption spectroscopy) type experiments with Xe and Hg atoms. The results show that Hg atom may become a good candidate for a search for the $\mathcal{P}$,$\mathcal{T}$-odd effects in atomic physics.

Оптический эффект вращения плоскости поляризации света в ДНК-содержащих материалах

AbstractUsing the example of DNA water solutions, a manifestation of the light polarization plane rotation effect has been shown (in comparison with a number of dyes). Numerical values of the rotation angle have been established that significantly exceed those for water solutions of dyes and sugar traditionally used in saccharimeters and polarimeters. Therefore, another optical effect in biostructuring optical materials has been identified and confirmed.

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.

Experimental Investigation of the Polarization Plane Rotation of Light in Cholesteric Liquid-Crystalline Film with an Anisotropic Defect Layer

This paper experimentally demonstrated that in the cholesteric liquid-crystalline films it is possible to induce defect, which can be controlled by external electric field. Three cases of induced defects were examined and the main result of the experiment is that the rotation of polarization plane has maximum value when light first propagates through chiral liquid-crystalline photonic structure and then falls to the anisotropic layer. We have also supporting calculations, showing an agreement between experimental results and theoretical calculations. We present a new liquid crystal device configuration that performs as a tunable linear polarizer for both polarized and unpolarized lights.

Magnetic Field Effect on the Localized Plasmon Resonance in Patterned Noble Metal Nanostructures

Sizable rotation of light polarization plane induced by magnetic field when transmitting through gold nanostructures was observed which was characterized by Faraday rotation and ellipticity. The dependence of disk diameter and disk to disk distance were investigated. The plot of Faraday effect versus disk diameter showed resonant features which were associated with the excitation of localized surface plasmon (LSPR). The magnitude of Faraday rotation or ellipticity from gold nanodisks was found to be at the order of 0.01 degree at magnetic field of 1 Tesla. The MO activity was modeled by the effective medium model, resonant behavior was observed around LSPR resonance and the magnitude of experimental MO activities show good correspondence with the calculation. The results suggest active control on the plasmonic modes by external magnetic field.

Analog of the Umov experiment in a birefringent medium

Classical demonstration experiment on visualization of light polarization plane rotation in an optically active medium is the Umov experiment [1–4]. When a collimated polarized light beam passes through an optical cell filled with a sugar solution in water and radiation scattered at an angle of 90o to the direction of beam propagation is observed, a bright dashed line typical of light scattered in an isotropic medium is seen rather than a solid line. The essence of the phenomenon is that when the beam passes through the active medium, its polarization plane is rotated. Due to the fact that the electromagnetic waves are transverse in character, the scattered light intensity vanishes when the direction of light polarization plane coincides with the observation direction. Because the effect is rather weak, to observe several tracks, the cell length must be no smaller than ∼1 m (even when it is filled with the concentrated sugar solution). Analogous character of scattering is observed in crystalline media [5–7] in which the beam polarization state also changes during beam propagation. However, because the birefringence effect in crystals is generally relatively strong, the similar scattering pattern can be seen with naked eye only in the direction close to the optical crystal axis where its intensity is low. In the present work, experiments on light scattering in an Icelandic spar crystal and a Plexiglas bar are described. Linearly polarized He-Ne laser or laser pointer radiation with power 10 mW P ≤ passed through the spar crystal of low optical quality (red and green pointers were used). To observe a scattering track stripe in the crystal, the laser beam was incident in the direction close to the optical crystal axis (Z-cut). Figure 1a shows a photograph of the scattering pattern in the spar crystal 4.2 cm long. Since the birefringence intensity in the crystal depends on the direction of light propagation, smooth crystal rotation causes changes in the scattering stripe period. They were observed in our experiment. The bright dashed scattering straight line can also be observed in plexiglass where, as a rule, small residual birefringence is always presented [7]. Figure 1b shows a photograph of light scattering pattern in the organic glass rod 50 cm long. In both cases, no professional polishing of specimen sides is required for clear visibility of tracks. Their simple coating is sufficient. The birefringence intensity of the medium n Δ is related to the track period Λ by the formula / n Δ = λ Λ ; it is determined exactly enough. Based on observations of the scattering pattern through a polaroid that is rotated, it is easy to verify that radiation scattered at an angle of 90o is almost completely polarized. The above-described experiments whose ideology and observed pattern are analogous to the Umov experiment are performed with simple accessible materials. The track stripe of scattered light in both cases is well seen by naked eye in slightly turbid specimens in a darkened room. The experiments on measuring the optical anisotropy of the medium for light scattering can provide the basis for a laboratory work or a demonstration experiments for a large audience.

All-Optical Integrated Switch Utilizing Faraday Rotation

Achieving network transparency via the use of all-optical devices is vital for next generation DWDM networks to realize fundamental functions such as switching, routing and wavelength conversion. With the abundance of capacity created by the Internet boom of the '90s, emphasis is placed on both device performance and cost. A 1 × 1 integrated switch based on the polarization plane rotation of light in Bi-substituted iron garnets is reported here using a Mach-Zehnder interferometer to achieve amplitude modulation by use of suitable material dimensions and field strengths. The working principle, design and fabrication of the switch are detailed.

Maxwell equations with accounting of tensor properties of time

The Maxwell equations with accounting for tensors properties of time have been considered. The effects that follow from such consideration are described. These are the appearance of vacuum polarization, anisotropy of electromagnetic wave velocity in vacuum, anisotropy of the vacuum dielectric permittivity, rotation of light polarization plane, as well as the existence of longitudinal components of electromagnetic wave and the rotational (non-potential) component of electric field caused by electric charges.

A novel and direct assay for measuring enzymatic depolymerisation of ?-1,3-glucans

Indirect colorimetric analyses of released reducing groups, as an indicator of induced β-1,3-glucanase activities, tend to be the assay methods of choice for the characterization of plant endo- and exo-β-1,3-glucanase. However, interfering low molecular weight reducing sugars found in unprocessed plant extracts often mask in vitro estimations of β-1,3-glucanase activity. The enzyme-catalysed hydrolysis of an optically active β-1,3-glucan polymer was monitored polarimetrically by measuring changes in the rotation of plane-polarized light of the reaction assay medium. A direct, non-radiochemical assay that detects changes in the optical rotation of released (13) β-D-oligoglucosides with low degrees of polymerisation (≪25) has been found to be highly reproducible, rapid (total analysis time 15 min), sensitive (detection limit 0.007 unit/mL glucanase), selective and non-destructive. This assay has been used to detect a salicylate-induced cell wall-bound tomato β-1,3-glucanase, which is a component of a pathogenesis-related response in plants. Copyright © 2000 John Wiley & Sons, Ltd.

Influence of the magnetic field on the rotation of light polarization plane in the cholesteric liquid crystal

Influence of the magnetic field on the rotation of light polarization plane in the cholesteric liquid crystal

Light-Controlled Rotation of the Light Polarization Plane in Weakly Twisted Nematics

Abstract The effect of a light polarization plane rotation in a cell with weakly twisted nematic liquid crystal (LC) caused by phototransformation of chiral molecules has been found. Such a behavior was stimulated by trans-cis isomerization of twisting agent resulting in a strong decrease of its twisting power. Non-stimulated cholesteric spiral unwinding was observed after an exciting light had been switched off.

Precision laser spectropolarimetry

A procedure for precision measurements of small angle rotation of light polarization plane vs wavelength is described. Analyzed at length is the optical spectropolarimeter configuration, wherein the frequency-dependent instrumental rotations are suppressed to the maximum degree. The sensitivity and the accuracy of the technique are illustrated by the examples of measuring the optical activity of atomic bismuth caused by parity nonconservation and the spectral profiles of the Faraday rotation.

Specular optical activity in GaAs

We report the first experimental observation of light polarization plane rotation, of approximately 10 -3 rad, on normal reflection from a [001] GaAs surface. The rotation is attributed to both surface anisotropy and bulk crystal nonlocality due to violation of time-reversibility, appearing from the importance of the electron spin-orbit interaction.

Analysis of Magneto-Optic Readout with Circular Polarized Light

This paper presents a new design for magneto-optical pickups which detect the phase shift of circularly polarized light instead of the rotation of plane-polarized light. The use of a polarizing beam splitter and a quarter-wave plate enables a theoretical efficiency of 100%. Efficiency is important not only in order to reduce the laser power when recording, but also to avoid reflected light which would interfere with the laser output. We discuss the theory of readout from circularly polarized light and describe an experiment on reading from a rare earth-iron garnet magneto-optical disk. In conclusion, we discuss the advantages and drawbacks of such a reading method.

Optical Activity and Ferroelectricity in Liquid Crystals

Some liquid-crystalline phases of optically active materials are themselves optically active and have dissymmetric structures. The cholesteric phase and smectics C,I, and F have a helical order of their molecules. Plane-polarized light is rotated by the helix, and when the pitch of the helix is comparable to the wavelength of visible light, these phases will reflect irridescent light of a single color. The smectics phases can exhibit ferroelectricity and have been utilized recently in fast-switching light valves. A relation between the microscopic property of molecular configuration and the macroscopic properties of ferroelectricity and the rotation of plane-polarized light is developed.