Measurement of the four Stokes polarization parameters with a single circular polarizer

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.     

利用斯托克斯参量验证偏振光

利用斯托克斯参量表示入射光的偏振特性,给出了斯托克斯各参量测量方法与计算原理,通过实验和关系转换,进而可更直观地判断光的偏振态.     

Spin polarization in quantum dots by radiation field with circular polarization

For circular quantum dot (QD), taking into account the Razhba spin-orbit interaction (SOI), an exact energy spectrum is obtained. For a small SOI constant, the eigenfunctions of the QD are found. It is shown that the application of a radiation field with circular polarization removes the Kramers degeneracy of the QD eigenstates. Effective spin polarization of electrons transmitted through the QD owing to a radiation field with circular polarization is demonstrated.     

Manipulating near field polarization beyond the diffraction limit

We introduce a new optical nanoantenna structure with three-fold rotational symmetry. The proposed gold nanoantenna can produce a hot spot with circular polarization in the gap. The effect of the shape of the arms and geometrical imperfection on the optical response is examined. We introduce a figure of merit for practical applications that utilize the circular polarization. The figure of merit is more sensitive to changes of the geometry than the maximum near field amplitude or the maximum circular polarization. The relatively equivalent optical response of the proposed nanoantenna compared to its counterparts and its reasonable stability against small changes accompanied with its simpler structure design makes it more appropriate for experimentalists.     

Reconstruction of the polarization states of a biphoton field

A method for reconstructing an arbitrary quantum state of an optical system in Hilbert space with dimension d = 4 is discussed. Such states can be realized using a collinear frequency-nondegenerate regime of generating spontaneous parametric down-conversion. The method has been tested for a number of polarization states of a biphoton field. The high accuracy of the reconstruction of the states (above 99%) indicates that the procedures proposed for reconstructing the quantum state of the system are adequate.     

Imprints of molecular orbitals using photoelectron angular distribution by strong laser pulses of circular polarization

We theoretically investigate the strong-field ionization of H+2 molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields. We find that the structure of photoelectron angular distribution depends on the molecular orbital as well as the energy of the photoelectron. The location of main lobes changes with the symmetric property of the molecular orbital. Generally, for molecules with bonding electronic states, the photoelectron's angular distribution shows a rotation of π/2 with respect to the molecular axis, while for molecules with antibonding electronic states, no rotation occurs. We use an interference scenario to interpret these phenomena. We also find that, due to the interference effect, a new pair of jets appears in the waist of the main lobes, and the main lobes or jets of the photoelectron's angular distribution are split into two parts if the photoelectron energy is sufficiently high.     

Local field enhancements on gold and silver nanostructures for aperture near field spectroscopy

Optical properties of silver and gold semi-continuous films near the percolation threshold are investigated by scanning near field optical microscopy (SNOM) operating in the collection/transmission mode. The electromagnetic enhanced fields, due to plasmon-polariton localizations, are observed and the intensity distribution is shown to present high intensity variations that increase with the wavelength. The local fields are also demonstrated to be polarization dependent. The intensity distribution is investigated as function of the incident wavelength both for gold and silver films. The calculated probability distribution function (PDF) exhibits an exponential decay for large enhancement factors and is proved to be wavelength dependent.     

Stabilization of circular states of the hydrogen atom in a strong field

A solution of the three-dimensional time-dependent Schrödinger equation, describing the ionization dynamics of the hydrogen atom in a circular state in an electromagnetic field, is obtained by direct numerical integration. It is shown that the observed stabilization effect can be interpreted on the basis of the Kramers-Henneberger approach. A simple analytical model is proposed, which qualitatively describes the basic laws of the ionization process under the conditions of the reported calculations and laboratory experiments on ionization of the circular hydrogenlike 5g, m=4 state of the Ne atom.     

Multi-mJ pulse compression in hollow fibers using circular polarization

We develop a numerical model to explore the polarization-dependent compression of multi-mJ laser pulses in a gas-filled hollow fiber. We show how losses and instabilities due to cycling of pulse energy between fiber modes can be efficiently minimized using circularly polarized light and adjusting simple experimental parameters such as pulse energy, chirp and gas pressure. This should help scale the peak power of few-cycle pulses available for high-field experiments using standard hollow fiber compressors. We also discuss the limits of this approach.     

Piezospin polarization of currents in nanostructures

Torsional oscillations of a freestanding semiconductor beam are shown to cause spin-dependent oscillating potentials that spin polarize an applied charge current in the presence of intentional or disorder scattering potentials. We propose several realizations of mechanical spin generators and manipulators based on this piezospintronic effect.     

Electric field as a switching tool for magnetic states in atomic-scale nanostructures

One of the most promising candidates for the construction of ultrahigh-density storage media is low-dimensional atomic-scale magnetic nanostructures exhibiting magnetic bi- or multistability. Here we propose a novel route of locally controlling and switching magnetism in such nanostructures. Our ab initio studies reveal that externally applied electric field can be used for this purpose.     

Magnetic-field-induced electric polarization in multiferroic nanostructures

Magnetic-field-induced electric polarization in nanostructured multiferroic composite films was studied by using the Green's function approach. The calculations showed that large magnetic-field-induced polarization could be produced in multiferroic nanostructures due to enhanced elastic coupling interaction. Especially, the 1-3 type films with ferromagnetic nanopillars embedded in a ferroelectric matrix exhibited large magnetic-field-induced polarization responses, while the 2-2 type films with ferroelectric and ferromagnetic nanolaminates showed much weaker magnetoelectric coupling and lower magnetic induced polarization due to large in-plane constraint effect, which was in agreement with the recent observations.     

Reflective thin-film device for generating spatial binary patterns of orthogonal circular polarization states

A novel device is described that generates, by reflection, polarized optical wavefronts of juxtaposed fields of alternating orthogonal circular polarization states. It consists of a dielectric substrate coated by a transparent thin film of certain refractive index and of thickness that alternates between two discrete values over adjacent areas of the substrate, in a pattern that corresponds to the desired binary polarization pattern of the reflected wave. Devices that use Ge and Si substrates at wavelengths of 10.6 and 0.6328 μm, respectively, are presented as examples.     

Electronic states in magnetic nanostructures

The electronic states responsible for oscillatory magnetic coupling, giant magnetoresistance (GMR), and spin-polarized tunneling are explored. They occupy well-defined locations in (E, k) space. Their energy E has to be within a few kT of the Fermi level, a range that is now becoming accessible to high-resolution photoemission. Particular attention is paid to k-regions near the Fermi level crossings of the s, p-band, where a sizable group velocity is combined with a d-like magnetic splitting and spin-polarization. These electronic states can be tailored by quantization in structures with single-digit nanometer dimensions, such as two-dimensional quantum wells and one-dimensional arrays of stripes and dots. Such arrays can be produced by self-assembly on top of stepped silicon surfaces.     

Classification of singular points in the polarization field of the cosmic microwave background and eigenvectors of the Stokes matrix

An analysis is made of the singularities of the polarization field of the cosmic microwave background, where the polarization is equal to zero. It is found that the classification of the singular points differs from the usual three types known in ordinary differential equations. The new statistical properties of the polarization field are discussed, and new methods to detect the presence of primordial tensor perturbations are indicated. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 6, 395–401 (25 March 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Analysis of polarization state in quantum key distribution via single-photon two-qubit states

An improved quantum key distribution scheme via single-photon two-qubit states is proposed. The input–output model of the polarization state is established. And the influence of the interferometers to the polarization state is analyzed. Quantum bit error rate of polarization coding caused by birefringent and coordinate system difference between incident light and the fast and slow axes in fiber interferometer is simulated. Furthermore, maintaining conditions of polarization state are given on this basis.     

Full vector treatment of the polarization evolution in an arbitrary field distribution

This paper presents a vector representation of the ensemble muon polarizationP(t) for static field distributions which emphasizes the different behavior resulting from correlated and non-correlated field distributions. For example, with most local field distributions, such as random dipolar fields, the net muon polarization in the limit of infinite timeP(t) is parallel to the initial muon spin direction when the using transverse field (TF) or longitudinal field (LF) geometries. In general, however, it need not be; this will be demonstrated using the field distribution of an anisotropic superconductor.