共查询到20条相似文献,搜索用时 15 毫秒
1.
E. H. Khoo I. Ahmed Z. Guo V. Dixit M. T. W. Ang E. P. Li 《Applied Physics A: Materials Science & Processing》2013,112(3):597-603
In this paper, the near field distribution patterns formed from nanostripe corral and half spiral are investigated. Various near field distribution patterns are generated owning to the interference of propagating surface plasmon waves that emerged from the nanoslits or nanostripe. The half spiral nanoslits are illuminated with Stokes polarizations. Each polarization state shows a different field pattern at different locations on the surface of metal film. This is due to the excitation of surface plasmon waves at different parts of the nanostructures when illuminated with different types of polarization states. The same Stokes polarization states are also illuminated on a nanostripe corral structure. In this case, dipolar field distributions are observed when illuminated with different linear polarization states, while optical vortices are observed for circular polarization. It is believed that these interesting field patterns due to different arrangements of nanostructures could be used for near field imaging and polarization sensing. 相似文献
2.
B. I. Ryabov 《Radiophysics and Quantum Electronics》1998,41(3):169-176
Solar observations with a new panoramic spectrum analyzer (PSA) of RATAN-600 showed the multiple inversion of the sense of
circular polarization in microwave local sources (LSs). The polarization spectra of LSs are analyzed in terms of the theory
of linear coupling of ordinary and extraordinary modes in the quasitransverse (QT) region. We consider the RATAN-600 radio
observations of June 2, 1977, January 10, 1992, and May 9 and 10, 1992 for the LS, which demonstrated the inversion of polarization
sense in the range 2.0–6.5 cm. The theory of QT propagation imposes a constraint on the degree of polarization of microwaves
at wavelengths close to the inversion wavelength. The dependence of the multiple inversion on the wavelength due to multiple
crossing of QT regions is verified. The LS polarization spectra are correlated with the spectra calculated for a varied multiplicity
to determine more accurately the multiplicity of the inversion.
We propose that the multiple inversion is due to the fine structure of the coronal magnetic field. The analysis of this phenomenon
allows the coronal magnetic field in the active region to be determined simultaneously at several heights.
Ventspils International Radioastronomy Center, Riga, Latvia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 41, No. 3, pp. 259–269, March, 1998. 相似文献
3.
Expressions for the Stokes parameters when radio waves propagate in a turbulent magnetoactive plasma have been obtained using a refractive scattering method. The problem of the spatial coherence of polarized radiation is considered. Expressions for the correlation functions and fluctuation dispersions of the Stokes parameters are found in the case of saturated wave field fluctuation. It is shown that the fluctuation of the circular polarized component will be observed in the received radiation even if the circular polarization is absent in the radiation that is incident on the magnetoactive plasma slab. A method is proposed to define the preference orientation of the magnetic field in the inhomogeneous layer of space plasma, which is biased on the simultaneous measurement of the space correlation functions of the I, V Stokes parameter fluctuation and Faraday rotation of the radiation polarization plane from the source with known polarization characteristics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 8, pp. 1007–1013, August, 1996.This work was supported in part by the Russian Foundation for Fundamental Research under Project No. 96-02-18632. 相似文献
4.
Peter K. Anastasovski T. E. Bearden C. Ciubotariu W. T. Coffey L. B. Crowell G. J. Evans M. W. Evans R. Flower S. Jeffers A. Labounsky D. Leporini B. Lehnert M. Mészáros J. K. Moscicki P. R. Molnár H. Múnera E. Recami D. Roscoe S. Roy 《Foundations of Physics Letters》1999,12(3):251-265
The general theory of gauge fields is used to develop a theory of electrodynamics in which the fundamental structure is non-Abelian and in which the internal gauge field symmetry is O(3), based on the existence of circular polarization and the third Stokes parameter. The theory is used to provide an explanation for the Sagnac effect with platform at rest and in motion. The Sagnac formula is obtained by considering the platform in motion to be a gauge transformation. The topological phases can be described straightforwardly with non Abelian electrodynamics, which produces a novel magnetic field component for all types of radiation, a component which is proportional to the third Stokes parameter. The theory provides a natural explanation for the inverse Faraday effect without phenomenology. 相似文献
5.
Larionov AV Kulakovskii VD Höfling S Schneider C Worschech L Forchel A 《Physical review letters》2010,105(25):256401
The effect of a magnetic field on a spinor exciton-polariton condensate has been investigated. A quenching of a polariton Zeeman splitting and an elliptical polarization of the condensate have been observed at low magnetic fields B<2 T. The effects are attributed to a competition between the magnetic field induced circular polarization buildup and the spin-anisotropic polariton-polariton interaction which favors a linear polarization. The sign of the circular polarization of the condensate emission at B<3 T is negative, suggesting that a dynamic condensation in the excited spin state rather than the ground spin state takes place in this magnetic field range. From about 2T on, the Zeeman splitting opens and from then on the slope of the circular polarization degree changes its sign. For magnetic fields larger than the 3 T, the upper spin state occupation is energetically suppressed and circularly polarized condensation takes place in the ground state. 相似文献
6.
7.
We present a relativistic model for the centrifugal acceleration of plasma bunches and the coherent radio emission in pulsar
magnetosphere. We find that rotation broadens the width of leading component compared to the width of trailing component.
We explain this difference in the component widths using the nested cone emission geometry. We estimate the effect of pulsar
spin on the Stokes parameters, and find that the inclination between the rotation and magnetic axes can introduce an asymmetry
in the circular polarization of the conal components. We analyse the single pulse polarization data of PSR B032954 at 606
MHz, and find that in its conal components, one sense of circular polarization dominates in the leading component while the
other sense dominates in the trailing component. Our simulation shows that changing the sign of the impact parameter changes
the sense of circular polarization as well as the swing of polarization angle
Article presented at the International Conference on the Frontiers of Plasma Physics and Technology, 9–14 December 2002, Bangalore,
India. 相似文献
8.
O. V. Vikhrova Yu. A. Danilov B. N. Zvonkov P. B. Demina M. V. Dorokhin I. L. Kalentyeva A. V. Kudrin 《Physics of the Solid State》2017,59(11):2216-2219
The radiative and magnetic properties of novel heterostructures with a bilayer InGaAs/GaAsSb/GaAs quantum well and a GaMnAs ferromagnetic layer are studied. The circular polarization of electroluminescent radiation is observed at temperatures from 10 to 160 K. The magnetic field dependences of the degree of circular polarization are nonlinear with a hysteresis loop at temperatures from 10 to 50 K, and they become linear at higher temperatures. The magnitude of polarization at the saturation magnetization of GaMnAs in the 2000 Oe field remains at the level of ~0.2%. 相似文献
9.
《Current Applied Physics》2018,18(11):1196-1200
We have experimentally demonstrated circular polarization generation from linear polarized soft X-ray at synchrotron by adopting a thin magnetic film polarizer. Polarizer is composed of Co/Pt multilayer with a perpendicular magnetic anisotropy, which allows us to easily accommodate without needing any tilting angle into the measurement setup since the circular polarization is generated for the X-ray with normal incidence and transmission. Generated circular polarization is examined by observing magnetic domain features based on the X-ray magnetic circular dichroism, where ∼11% of circular component is estimated compared to the case of full circular polarization. 相似文献
10.
M. V. Dorokhin M. V. Ved’ P. B. Demina A. V. Zdoroveyshchev A. V. Kudrin A. V. Rykov Yu. M. Kuznetsov 《Physics of the Solid State》2017,59(11):2155-2161
Spin injection in CoPt/Al2O3/(Al)GaAs spin light-emitting diodes (SLEDs) was studied. The oscillations of the degree of circular polarization upon variation of a distance between the active region of the SLED and a CoPt ferromagnetic injector were observed. The oscillations depend neither on a SLED material (GaAs or AlGaAs), nor on the type of injected spin-polarized carriers (electrons and holes) and are related to the action of a perpendicular magnetic field on the injected spin-polarized carriers that causes their precession. During the transfer to the active region through a distance of 50–100 nm from the injector, a z–component of a spin changes a phase that is detected experimentally as the change in sign of the degree of circular polarization of luminescence. Conceivably, a source of the internal magnetic field leading to spin precession is the magnetic field of the nonuniformly magnetized CoPt contact. 相似文献
11.
Measuring Stokes parameters by means of a polarization grating 总被引:3,自引:0,他引:3
Gori F 《Optics letters》1999,24(9):584-586
Ordinary gratings act on the amplitude and (or) the phase of a wave front. Polarization gratings produce instead a periodic modulation of the state of polarization. A simple grating of the latter type is constituted by a linear polarizer whose orientation varies periodically along a line. It is shown that, for a generic polarization state of the incident field, such a grating gives rise to first-order diffracted beams with counterrotating circular polarizations. It is also shown that such a grating can be used for measuring the Stokes parameters of a light beam in an achromatic manner. Several extensions are briefly discussed. 相似文献
12.
In a tokamak plasma, the poloidal magnetic field profile closely depends on the current density profile. We can deduce the internal magnetic field from the analysis of circular polarization of the spectral lines emitted by the plasma. The theory of the measurement and a detailed design of the Zeeman polarimeter constructed to measure the poloidal field profile in the ADITYA tokamak are presented. The Fabry-Perot which we have employed in our design, with photodiode arrays followed by lock-in detection of the polarization signal, allows the measurement of the fractional circular polarization. In this system He-II line with wavelength 4686 Å is adopted as the monitoring spectral line. The line emission used in the present measurement is not well localized in the plasma, necessiating the use of a spatial inversion procedure to obtain the local values of the field. 相似文献
13.
Edward Collett 《Optics Communications》1984,52(2):77-80
In this paper a method is developed to measure the four Stokes polarization parameters using a single circular polarizer. This is accomplished by measuring the first three Stokes parameters with the “circular” side of the polarizer facing the optical source and then flipping the polarizer to the “linear” side to determine the final Stokes parameter. 相似文献
14.
Imaging polarimeters infer the spatial distribution of the polarization state of the optical field as a function of time and/or wavelength. A polarimeter indirectly determines the polarization state by first modulating the intensity of the light field and then demodulating the measured data to infer the polarization parameters. This Letter considers passive Stokes parameter polarimeters and their inversion methods. The most widely used method is the data reduction matrix (DRM), which builds up a matrix equation that can be inverted to find the polarization state from a set of intensity measurements. An alternate strategy uses linear system formulations that allow band limited reconstruction through a filtering perspective. Here we compare these two strategies for overdetermined polarimeters and find that design of the null space of the inversion operator provides degrees of freedom to optimize the trade off between accuracy and signal-to-noise ratio. We further describe adaptive filtering techniques that could optimize the reconstruction for a particular experimental configuration. This Letter considers time-varying Stokes parameters, but the methods apply equally to polarimeters that are modulated in space or in wavelength. 相似文献
15.
Quantum spin transport through Aharonov--Bohm ring with a tangent magnetic field 总被引:1,自引:0,他引:1
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Quantum spin transport in a mesoscopic Aharonov--Bohm ring with two leads subject to a magnetic field with circular configuration is investigated by means of one-dimensional quantum waveguide theory.Within the framework of Landauer--B\"{u}ttiker formalism, the polarization direction of transmitted electrons can be controlled either by the AB magnetic flux or by the tangent magnetic field. In particular, the spin flips can be induced by hopping the AB magnetic flux or the tangent field. 相似文献
16.
17.
A. G. Petrashen’ 《Optics and Spectroscopy》2010,108(1):1-3
It is demonstrated that, in an atomic system on an isolated level, linear polarization can be transformed into circular polarization
in a weak electric field. If a weak magnetic field is applied to the system, a similar transformation is possible only in
the case of anisotropic excitation of Zeeman sublevels. 相似文献
18.
Carozzi T Karlsson R Bergman J 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(2):2024-2028
In this paper, generalizations of the Stokes parameters and alternative characterizations of three-dimensional (3D) time-varying electromagnetic fields is introduced. One of these characteristics is the normal of the polarization plane, which, in many cases of interest, is parallel (or antiparallel) to the direction of propagation. Others are the two spectral density Stokes parameters which describe spectral intensity and circular polarization. The analysis is based on the spectral density tensor. This tensor is expanded in a base composed of the generators of the SU(3) symmetry group, as given by Gell-Mann and Y. Ne'eman [The Eight-fold Way (Benjamin, New York, 1964)] and the coefficients of this expansion are identified as generalized spectral density polarization parameters. The generators have the advantage that they obey the same algebra as the Pauli spin matrices, which is the base for expanding the 2D spectral density tensor with the Stokes parameters as coefficients. The polarization parameters introduced are formulated in the frequency domain, thereby further generalizing the theory to allow for wide-band electromagnetic waves in contrast to the traditional quasi-monochromatic formulation. 相似文献
19.
M. Ya. Agre 《Journal of Experimental and Theoretical Physics》2001,93(3):491-498
A compact expression is derived for the cross section of scattering of arbitrarily polarized light by oriented atomic systems, in which the dependence on the geometric parameters and on the Stokes parameters preassigning the state of partial polarization of incident radiation is explicitly separated. It is found that the cross section of any photoprocess accompanied by photon absorption (stimulated emission) contains the sum of the products of the circular and linear dichroisms of the process by the respective Stokes parameters. The effect of the atomic orientation and of the dissipation of light energy on the polarization singularities and angular distribution of scattered light is investigated. In particular, it is demonstrated that, in the case of an open dissipation channel, the angular distribution remains dependent on the atomic orientation even in the case of zero degree of circular polarization of scattered radiation. 相似文献
20.
Sadjadi FA 《Optics letters》2007,32(3):229-231
The results of experiments in developing a method for extracting three-dimensional information from a scene by means of a polarimetric passive imaging sensor are summarized. This sensor provides a full Stokes vector at each sensor pixel location from which degree and angle of linear polarization are computed. The angle of linear polarization provides the azimuth angle of the surface normal vector. The depression angle of this surface normal vector is obtained in terms of the emitting object's index of refraction from the solution of an equation derived from Fresnel equations, Snell's law, and percent of linear polarization. Results of the application of this approach to simulated infrared polarimetric data are provided. 相似文献