Rotation Of Polarization Vector Research Articles

Effects of geometric optics in conformal Weyl gravity

We have investigated effect of geometric optics as the rotation of polarization vector of light in spacetime of gravitational compact object in the fourth-order theory of conformal Weyl gravity. The Pineault–Roeder method is applied to the rotating Weyl metric, and analytical results are obtained in the limit of weak field and or slow rotation. For the photon traveling parallel to the symmetry axes from the equatorial plane to infinity, the rotation of the polarization plane depends on the Weyl parameter gamma on the contrary to the Kerr spacetime where there is no rotation of polarization plane for this case.

THE EFFECT OF GRAVITATION ON THE POLARIZATION STATE OF A LIGHT RAY

ABSTRACT In the present work, detailed calculations have been carried out on the rotation of the polarization vector of an electromagnetic wave due to the presence of a gravitational field of a rotating body. This has been done using the general expression of Maxwell’s equation in curved spacetime. Considering the far-field approximation (i.e., the impact parameter is greater than the Schwarzschild radius and rotation parameter), the amount of rotation of the polarization vector as a function of impact parameter has been obtained for a rotating body (considering Kerr geometry). The present work shows that the rotation of the polarization vector cannot be observed in the case of Schwarzschild geometry. This work also calculates the rotational effect when considering prograde and retrograde orbits for the light ray. Although the present work demonstrates the effect of rotation of the polarization vector, it confirms that there would be no net polarization of an electromagnetic wave due to the curved spacetime geometry in a Kerr field.

Monoclinic Cc-phase stabilization in magnetically diluted lead free Na1/2Bi1/2TiO3—Evolution of spin glass like behavior with enhanced ferroelectric and dielectric properties

The effect of magnetic cation substitution on the phase stabilization, ferroelectric, dielectric and magnetic properties of a lead free Na0.5Bi0.5TiO3 (NBT) system prepared by O2 atmosphere solid state sintering were studied extensively. Cobalt (Co) was chosen as the magnetic cation to substitute at the Ti-site of NBT with optimized 2.5 mol%. Rietveld analysis of x-ray diffraction data favours the monoclinic Cc phase stabilization strongly rather than the parent R3c phase. FE-SEM micrograph supports the single phase characteristics without phase segregation at the grain boundaries. The stabilized Cc space group was explained based on the collective local distortion effects due to spin–orbit stabilization at Co3+ and Co2+ functional centres. The phonon mode changes as observed in the TiO6 octahedral modes also support the Cc phase stabilization. The major Co3+-ion presence was revealed from corresponding crystal field transitions observed through solid state diffuse reflectance spectroscopy. The enhanced spontaneous polarization (Ps) from ≅38 μC cm−2 to 45 μC cm−2 could be due to the easy rotation of polarization vector along the in Cc phase. An increase in static dielectric response (ϵ) from ϵ ≅ 42 to 60 along with enhanced diffusivity from γ ≅ 1.53 to 1.75 was observed. Magneto-thermal irreversibility and their magnetic field dependent ZFC/FC curves suggest the possibility of a spin glass like behaviour below 50 K. The monoclinic Cc phase stabilization as confirmed from structural studies was well correlated with the observed ferroic properties in magnetically diluted NBT.

ON THE ADIABATIC WALKING OF PLASMA WAVES IN A PULSAR MAGNETOSPHERE

The pulsar radio emission is generated in the near magnetosphere of the neutron star and it has to propagate through the rest of it to emerge into the interstellar medium. An important issue is whether this propagation affects the planes of polarization of the generated radiation. Observationally, there is a sufficient evidence that the emerging radiation is polarized parallel or perpendicular to the magnetic field line planes that should be associated with the ordinary O and extraordinary X plasma modes respectively, excited by some radiative process. This strongly suggests that the excited X- and O-modes are not affected by the so-called Adiabatic Walking that causes a slow rotation of polarization vectors. In this paper we demonstrate that the conditions for the Adiabatic Walking are not fulfilled within the soliton model of pulsar radio emission, in which the coherent curvature radiation occurs at frequencies much lower than the characteristic plasma frequency. The X-mode propagates freely and observationally represents the primary polarization mode. The O-mode has difficulties in escaping from the pulsar plasma, nonetheless it is sporadically observed as a weaker secondary polarization mode. We discuss a possible scenario under which the O-mode can also escape from the plasma and reach an observer.

Measurement of acoustic wave frequency by Bragg light diffraction.

The new technology is offered for measurement of acoustic wave frequency. The method is based on using the Bragg light diffraction on the hypersonic transversal acoustic wave in a gyrotropic crystal. As is well known, the intensity of diffracted light in this case is strongly dependent from the quantity of specific rotation of polarization vector. As a result, using the standard calibration of light intensity it is possible to measure the changes of acoustic wave frequency. Measurements of the diffracted light intensity have been carried out in several points along the direction of the acoustic wave propagation. The applied sample of LiNbO3 was oriented along the crystallographic axis of the third order with the accuracy of 10′. The plane‐polarized transverse acoustic waves were excited in the frequency range from 900 MHz to 1.2 GHz. The results obtained at the average frequency 1.0 GHz were shown, that the intensity of diffracted light intensity is sensitive parameter to the change of the transverse acou...

Polarisation Characteristics of Pulsations Associated with Storm Sudden Commencements.

Polarisation properties of magnetic pulsations associated with SCs recorded at an equatorial station, Choutuppal (Gm. Lat.: 7.5°N), during the years 1970-88 have been analysed. The results show that in contrast to a well defined local time dependent sense of rotation of polarisation vector reported for high and middle latitude pulsations (Wilson and Sugiura, 1961; Lanzerotti et al., 1981), the equatorial pulsations exhibit a predominantly clockwise sense of rotation particularly from around 22 hrs to early afternoon hours (13 to 14 hrs LT) while the events occurring later in the afternoon exhibit, in addition, a counter clockwise sense as well. The results for this equatorial station are consistent with the observations reported for very low latitude stations (Yumoto, 1986), thus indicating a latitudinal factor in characterising the local time dependence of sense of rotation of polarisation vector. The results are discussed in relation to the existing models invoking the azimuthally travelling ionospheric eddy currents for the immediate source of equatorial pulsations.

Rotation of Polarization Vector and Depolarization inp−pScattering

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