Rotation Angle Of Polarization Plane Research Articles

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.

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.

Two-Degree-of-Freedom Control of Field Distribution on Nonreciprocal Metamaterial-Line Resonators and Its Applications to Polarization-Plane-Rotation and Beam- Scanning Leaky-Wave Antennas

Two-degree-of-freedom control of field distribution on the pseudotraveling wave resonator using nonreciprocal metamaterial lines is demonstrated for the first time. Dynamic control of current distribution on the resonator is given based on circuit theory. We employed a normally magnetized ferrite microstrip line-based composite right-/left-handed (CRLH) transmission line as a metamaterial with variable phase-shifting nonreciprocity. Numerical simulation results show that the phase gradient of the fields along the resonator is controlled by the applied dc magnetic field to the ferrite. By changing the reflection coefficients of two reflectors inserted at both ends of the CRLH line section, current distribution along series and shunt branches of the unit cell is continuously and drastically changed under the resonance. The variable field distribution was implemented to polarization-plane-rotation and beam-scanning leaky-wave antennas. The experimental demonstration verifies our basic concept and shows the performance of the prototype antenna with a beam scanning angle of 20° and a continuous rotation angle of polarization plane by ±70° at the fixed frequency.

Implementation of amplitude–phase analysis of complex interferograms for measurement of spontaneous magnetic fields in laser generated plasma

Generation of spontaneous magnetic fields (SMFs) is one of the most interesting phenomena accompanying an intense laser–matter interaction. One method of credible SMFs measurements is based on the magneto-optical Faraday effect, which requires simultaneous measurements of an angle of polarization plane rotation of a probe wave and plasma electron density. In classical polaro-interferometry, these values are provided independently by polarimetric and interferometric images. Complex interferometry is an innovative approach in SMF measurement, obtaining information on SMF directly from a phase–amplitude analysis of an image called a complex interferogram. Although the theoretical basis of complex interferometry has been well known for many years, this approach has not been effectively employed in laser plasma research until recently; this approach has been successfully implemented in SMF measurement at the Prague Asterix Laser System (PALS). In this paper, proprietary construction solutions of polaro-interferometers are presented; they allow us to register high-quality complex interferograms in practical experiments, which undergo quantitative analysis (with an original software) to obtain information on the electron density and SMFs distributions in an examined plasma. The theoretical foundations of polaro-interferometric measurement, in particular, complex-interferometry, are presented. The main part of the paper details the methodology of the amplitude–phase analysis of complex interferograms. This includes software testing and examples of the electron density and SMF distribution of a laser ablative plasma generated by irradiating Cu thick planar targets with an iodine PALS laser at an intensity above about 1016 W/cm2.

Features of electromagnetic wave propagation in a longitudinally magnetized gyrotropic elliptic waveguide

In scientific literature the electromagnetic waves propagation in gyrotropic elliptic waveguides has not been studied enough due to: 1) difficulties of deriving Helmholtz equations for gyrotropic elliptic waveguides in arbitrary magnetization directions, 2) difficulties of solving Helmholtz equations and deriving the dispersion equations, 3) difficulties of solving the dispersion equations themselves. In this work, for the first time, dispersion equations for longitudinally magnetized gyrotropic elliptic waveguides were solved. Basing on the solutions results, the dependencies of the constant propagation: 1) on the strength and direction of the magnetizing field, 2) on the waveguide ellipticity at a constant ferrite magnetization were investigated. Studies have revealed previously unknown features inherent only to the electromagnetic waves in such waveguides propagation and showed that: 1) with the ferrite magnetization increase -3,1 times the polarization plane rotation angle increases by «5,4 times; 2) the gyrotropic elliptic waveguide polarization plane rotation angle is greater than that of a similar round waveguide. The results show the main advantage of gyrotropic elliptic guide systems over circular ones consists in the possibilities of varying both external and geometric parameters of gyrotropic elliptic guide systems and obtaining significant phase raids, which in turn allows developing more efficient phase shifters.

Magnetic field driven light control by hybrid magneto-optical metasurfaces

Demonstration of magneto-optical effects enhancement in hybrid Ni/Si metasurfaces is reported. Our results show that the polarization plane rotation angle reaches the considerable value with a change of a sign in a very narrow spectral range in the vicinity of the optical magnetic dipole Mie - type resonance. The specific Faraday rotation is 160 degrees/μm, which is an outstanding effect for an ultra-thin magnetic material with a thickness of only 5 nm as used in this work. These results could be used for the creation of active nonreciprocal photonic nanostructures and metasurfaces.

Millicharged fermion vacuum polarization in a cosmic magnetic field and generation of CMB elliptic polarization

The contribution of one loop milli-charged fermion vacuum polarization in cosmic magnetic field to the cosmic microwave background (CMB) polarization is considered. Exact and perturbative solution of the density matrix equations of motion in terms of the Stokes parameters are presented. For linearly polarized CMB at decoupling time, it is shown that propagation of CMB photons in cosmic magnetic field would generate elliptic polarization (circular and linear) of the CMB due to milli-charged fermion vacuum polarization. Analytic expressions for the degree of circular polarization and rotation angle of polarization plane of the CMB are presented. Depending on the ratio of milli-charged fermion relative charge to mass, $\epsilon/m_\epsilon$, and CMB observation frequency, it is shown that the acquired CMB degree of circular polarization could be of the order of magnitude $P_C(T_0)\sim 10^{-10}- 10^{-6}$ in the best scenario. The effect studied generates CMB polarization even in the case when the CMB is initially in thermal equilibrium. Limits on the magnetic field amplitude due to prior decoupling CMB polarization are presented.

Temperature measurement of photovoltaic cells surface

In this work a method of measuring the temperature of photocells is considered. A series of works are analyzed in which noted that temperature fluctuations of environment and photocell significantly affect output characteristics of photovoltaic cells. Temperature measurements are used in maximum power point tracking algorithms, for calculating the thermal coefficients of photocells. The described method uses yttrium iron garnet crystal placed in a constant magnetic field and magnetized to saturation as a sensing element of the device. To measure the temperature change the polarization plane rotation angle of transmitted light in the crystal dependence on temperature is used

Resonant features of planar Faraday metamaterial with high structural symmetry

The transmission of electromagnetic wave through a planar chiral structure, loaded with the gyrotropic medium being under an action of the longitudinal magnetic field, is studied. The frequency dependence of the metamaterial resonance and the angle of rotation of the polarization plane are obtained. We demonstrate both theoretically and experimentally a resonant enhancement of the Faraday rotation. The ranges of frequency and magnetic field strength are defined, where the angle of polarization plane rotation for the metamaterial is substantially higher than that one for a single ferrite slab.

The enhanced magneto-optical Kerr effect in Co/TiO2 multilayer films

Spectral dependences of the polarization plane rotation angle (θk) in the polar Kerr effect in Co/TiO2 multilayer nanocomposite films have been studied in the 400–1000 nm wavelength range. It is established that the sign, magnitude, and shape of the magneto-optical spectrum depend on the dielectric spacer thickness and the number of layers in the structure. The Kerr rotation angle in Co/TiO2 multilayers is significantly greater than that in homogeneous Co films of the same thickness. The angle of rotation of the polarization plane reaches a record high value of 2θk = 7.3° in the Co(5 nm)/TiO2(17 nm) multilayer structure with number of layers n = 8 at a wavelength of 540 nm.

Double-beam photopolarimeter for polarization plane rotation angle registration in turbid media

Double-beam photopolarimeter for polarization plane rotation angle registration in turbid media

Photonic-crystal properties of a 1D longitudinally magnetized periodic structure

Features of propagation of circularly polarized waves in a plane-layer periodic longitudinally magnetized ferromagnet—dielectric structure are studied. Dispersion relations and reflection coefficients are obtained, and frequency dependences of the Bloch wavenumber and reflection coefficients are constructed for natural waves of the periodic structure under investigation. The dependences of the polarization plane rotation angle in the polar Kerr effect on the frequency and the ratio of the thicknesses of layers over a period are constructed for various numbers of periods in the structure.

Polarimetry and Schlieren diagnostics of underwater exploding wires

Nondisturbing laser-probing polarimetry (based on the Faraday and Kerr effects) and Schlieren diagnostics were used in the investigation of underwater electrical wire explosion. Measuring the polarization plane rotation angle of a probing laser beam due to the Faraday effect allows one to determine an axially resolved current flowing through the exploding wire, unlike commonly used current probes. This optical method of measuring current yields results that match those obtained using a current viewing resistor within an accuracy of 10%. The same optical setup allows simultaneous space-resolved measurement of the electric field using the Kerr effect. It was shown that the maximal amplitude of the electric field in the vicinity of the high-voltage electrode is ∼80 kV/cm and that the radial electric field is <1 MV/cm during the wire explosion. Finally, it was shown that the use of Schlieren diagnostics allows one to obtain qualitatively the density distribution behind the shock wave front, which is important for the determination of the energy transfer from the discharge channel to the generated water flow.

Measurement of Polarization Plane Rotation of Propagating Light in a Partially Ionized Atmosphere under Discharge Conditions

The rotation angle of polarization plane of propagating beam was experimentally measured using a polarization controlled laser beam, repeating square mirror, and discharge apparatus. A rotation angle of 0.29 degrees was obtained in the case of discharge gap of 4 cm and charge voltage of 50 kV. The result was in good agreement with the simulation of the experimental model. The waveform of the rotation angle showed a similar time dependence as the discharge current, with a correlation coefficient of>0.94.

A medium with optical activity depending on the incoherent light intensity in a ring interferometer: Models of processes

As part of the program of developing perspective incoherent optics systems in which synergy phenomena are realizable, a complex of models of processes in a nonlinear ring interferometer with an optically active medium whose rotary power depends on the incoherent radiation intensity in the nonlinear ring interferometer is constructed. The light intensity depends nonlinearly on the angle of polarization plane rotation. The analogy of the constructed models with the well-known model of the nonlinear ring interferometer with the Kerr medium and laser radiation is established. The (non)linearity of the models and the application of the corresponding nonlinear ring interferometers are discussed. The results obtained are important for improvement in methods of natural light field processing.

Evaluation of Polarization Angle Rotation of Propagating Light in a Partially Ionized Atmosphere under Discharge Conditions

The rotation angle of polarization plane of propagating beam was experimentally measured using a polarization controlled laser beam, repeating square mirror, and discharge apparatus. A rotation angle of 0.29 degrees was obtained in the case of discharge gap of 4 cm and charge voltage of 50 kV. The result was in good agreement with the simulation of the experimental model. The waveform of the rotation angle showed a similar time dependence as the discharge current, with a correlation coefficient of>0.94.

Nonlinear rotation of the polarization of the intense femtosecond laser radiation in BaF2

The dependence of the polarization plane rotation angle in the BaF2 crystal on the intensity of the femtosecond laser radiation with 0.62 μm wavelength in the ω = ω + ω − ω process on cubical nonlinearity χ(3) is investigated. An anomalous increase in the efficiency of the cross-polarized radiation generation at I > 2 × 1012 W cm2 is observed for the first time. The 10% efficiency of the orthogonal component generation at the ∼3 × 1012 W cm2 intensity is obtained.

The laser in the axial electric field as a tool to search for P-, T-invariance violation

We consider rotation of the polarization plane of the laser light when a gas laser is placed in a longitudinal electric field (10 kV cm−1). It is shown that residual anisotropy of the laser cavity 10−6 and the sensitivity to the angle of polarization plane rotation about 10−11–10−12 rad allow one to measure an electron EDM with the sensitivity about 10−30e cm.

Gravitational faraday effect in curved space-time induced by high-power lasers

Gravitational field produced by high-power laser is calculated according to the linearized Einstein field equation in weak field approximation. Gravitational Faraday effect of electromagnetic wave propagating in the above gravitational field is studied and the rotation angle of polarization plane of electromagnetic wave is derived. The result is discussed and estimated under the condition of present experiment facility.

GRAVITATIONAL FARADAY EFFECT INDUCED BY HIGH-POWER LASERS

Gravitational field produced by high-power laser is calculated according to the linearized Einstein field equation in weak field approximation. Gravitational Faraday effect of electromagnetic wave propagating in the above gravitational field is studied and the rotation angle of polarization plane of electromagnetic wave is derived. The result is discussed and estimated in the condition of present experimental facility.