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We present a polarization-maintaining photonic bandgap fiber (PBGF) in terahertz (THz) regime, consisting of a quasi-elliptical hollow-core (QEHC) and triangularly arranged hexagonal holes in cladding. Thanks to the specially designed core shape, the QEHC-PBGF can support two stable polarization-maintaining fundamental modes. From numerical simulations, birefringence, confinement loss and group velocity dispersion of the fundamental mode group are 9.4 × 10 −4 , 3 × 10 −3 cm −1 and 0.39 psTHz −1 cm −1 at 0.9 THz, respectively. Moreover, we investigate the fiber fabrication tolerance in the context of polarization-maintaining and confinement performances. The proposed QEHC-PBGF is anticipated to be useful in polarization sensitive THz applications. [ABSTRACT FROM AUTHOR]

In this paper, we apply the mantle cloaking method to reduce the mutual coupling between two closely spaced wideband antennas operating at microwave frequencies. We show that by introducing two dielectric elliptical shells around the antennas and covering them with two strongly coupled elliptically shaped metasurfaces comprised of I-shaped printed unit cells, it is possible to significantly increase the original bandwidth of the antennas and, at the same time, reduce the mutual electromagnetic interaction. This effect is observed both in a reduction of mutual S-parameters between the antennas and in the restoration of the original radiation patterns, as if the antennas were almost completely isolated from each other. Broadband metasurface/cloak designs are proposed for two geometries, with the free-standing strip monopole antennas placed over a ground plane and with the metasurface cloaks integrated with microstrip antennas. [ABSTRACT FROM AUTHOR]

In implicit solvation models, the electrostatic contribution to the solvation energy can be estimated by solving a system of elliptic partial differential equations modeling the reaction potential. The domain of definition of such elliptic equations is the union of the van der Waals cavities corresponding to the atoms of the solute molecule. Therefore, the computations can naturally be performed using Schwarz methods, where each atom of the molecule corresponds to a subdomain. In contrast to classical Schwarz theory, it was observed numerically that the convergence of the Schwarz method in this case does not depend on the number of subdomains, even without coarse correction. We prove this observation by analyzing the Schwarz iteration matrices in Fourier space and evaluating corresponding norms in a simplified setting. In order to obtain our contraction results, we had to choose a specific iteration formulation, and we show that other formulations of the same algorithm can generate Schwarz iteration matrices with much larger norms leading to the failure of norm arguments, even though the spectral radii are identical. By introducing a new optimality concept for Schwarz iteration operators with respect to error estimation, we finally show how to find Schwarz iteration matrix formulations which permit such small norm estimates. [ABSTRACT FROM AUTHOR]

A partial correlation-based variable selection method was proposed for normal linear regression models by Büuhlmann, Kalisch and Maathuis (2010) as an alternative to regularization methods for variable selection. This paper addresses issues related to (a) whether the method is sensitive to the normality assumption, and (b) whether the method is valid when the dimension of predictor increases at an exponential rate in the sample size. To address (a), we study the method for elliptical linear regression models. Our finding indicates that the original proposal can lead to inferior performance when the marginal kurtosis of predictor is not close to that of normal distribution, and simulation results confirm this. To ensure the superior performance of the partial correlation-based variable selection procedure, we propose a thresholded partial correlation (TPC) approach to select significant variables in linear regression models. We establish the selection consistency of the TPC in the presence of ultrahigh dimensional predictors. Since the TPC procedure includes the original proposal as a special case, our results address the issue (b) directly. As a by-product, the sure screening property of the first step of TPC is obtained. Numerical examples illustrate that the TPC is comparable to the commonly-used regularization methods for variable selection. [ABSTRACT FROM AUTHOR]

Apple-type undulators are globally recognized as the most flexible devices for the production of variable polarized light in the soft X-ray regime, both at synchrotron and free-electron laser facilities. Recently, the implementation of transverse gradient undulators has been proposed to enhance the performance of new generation light sources. In this paper it is demonstrated that Apple undulators do not only generate linear and elliptical polarized light but also variable transverse gradient under certain conditions. A general theoretical framework is introduced to evaluate the K-value and its transverse gradient for an Apple undulator, and formulas for all regular operational modes and different Apple types (including the most recent Delta type and Apple X) are calculated and critically discussed. [ABSTRACT FROM AUTHOR]

We discuss the modified Maxwell action of a KF-type Lorentz symmetry breaking theory and present a solution of Maxwell equations derived in the cases of linear and elliptically polarized electromagnetic waves in the vacuum of CPT-even Lorentz violation. We show in this case that the Lorentz violation has the effect of changing the amplitude of one component of the magnetic field, while leaving the electric field unchanged, leading to nonorthogonal propagation of electromagnetic fields and dependence of the eccentricity on κ-term. Further, we exhibit numerically the consequences of this effect in the cases of linear and elliptical polarization, in particular, the regimes of nonorthogonality of the electromagnetic wave fields and the eccentricity of the elliptical polarization of the magnetic field with dependence on the κ-term. [ABSTRACT FROM AUTHOR]

The breaks and truncations in the luminosity profile of face-on spiral galaxies offer valuable insights in their formation history. The traditional method of deriving the surface photometry profile for face-on galaxies is to use elliptical averaging. In this paper, we explore the question whether elliptical averaging is the best way to do this. We apply two additional surface photometry methods, one new: principal axis summation, and one old that has become seldom used: equivalent profiles. These are compared to elliptically averaged profiles using a set of 29 face-on galaxies. We find that the equivalent profiles match extremely well with elliptically averaged profiles, confirming the validity of using elliptical averaging. The principal axis summation offers a better comparison to edge-on galaxies. [ABSTRACT FROM AUTHOR]

We present a geometric-analytic introductory treatment of polarization based on the circular polarization basis, which connects directly to the Poincaré sphere. This treatment enables a more intuitive way to arrive at the polarization ellipse from the components of the field. We also present an advanced optics lab that uses Poincaré beams, which have a polarization that is spatially variable. The physics of this lab can reinforce understanding of all states of polarization, and in particular, elliptical polarization. In addition, it exposes students to Laguerre-Gauss modes, the spatial modes used in creating Poincaré beams, which have unique physical properties. In performing this lab, students gain experience in experimental optics, such as aligning and calibrating optical components, using and programming a spatial light modulator, building an interferometer, and performing polarimetry measurements. We present the apparatus for doing the experiments, detailed alignment instructions, and lower-cost alternatives. [ABSTRACT FROM AUTHOR]

Multipactor effect is studied in a hollow elliptical waveguide carrying two orthogonal polarization modes, i.e., the fundamental (TEc11) and the second (TEs11) elliptical waveguide modes. The introduction of a modal equivalent voltage allows defining the standard axial ratio, which characterizes each polarization state of the problem. The RF breakdown threshold is determined as a function of the axial ratio, for various amplitudes, and phases of the two elliptical modes. In particular, the effect of second mode on the RF breakdown threshold of the fundamental mode is studied. The simulations are carried out for different values of the ellipse eccentricity. [ABSTRACT FROM AUTHOR]

Specific features of the acousto-optic diffraction of Bessel light beams propagating in the vicinity of the optical axis of a uniaxial gyrotropic crystal have been investigated. The dependences of the diffraction efficiency on the acousto-optic interaction length, ultrasound power, and polarization state of the incident Bessel light beam have been analyzed using the coupled-wave equations and the overlap-integral method. It is shown that polarization-independent diffraction of Bessel light beams is observed in paratellurite crystals, when the Bragg diffraction efficiency is independent of the polarization state of the incident beam. The physical reason for this diffraction has been established (both theoretically and experimentally) to be simultaneous implementation of two processes of anisotropic scattering, at which the Bragg synchronism conditions are satisfied for orthogonal polarized Bessel beams with elliptical polarization. [ABSTRACT FROM AUTHOR]

Photopolarimetry is the spatial characterization of light polarization. Unlike intensity or wavelength, we are largely insensitive to polarization and therefore find it hard to explore the multidimensional data that photopolarimetry produces (two spatial dimensions plus four polarization dimensions). Many different ways for presenting and exploring this modality of light have been suggested. Most of these ignore circular polarization, include multiple image panes that make correlating structure with polarization difficult, and obscure the main trends with overly detailed information and often misleading colour maps. Here, we suggest a novel way for presenting the main results from photopolarimetric analyses. By superimposing a grid of polarization ellipses onto the RGB image, the full polarization state of each cell is intuitively conveyed to the reader. This method presents linear and circular polarization as well as ellipticity in a graphical manner, does not require multiple panes, facilitates the correlation between structure and polarization, and requires the addition of only three novel colours. We demonstrate its usefulness in a biological context where we believe it would be most relevant. [ABSTRACT FROM AUTHOR]

The effect of an APPLE II-type elliptically polarized undulator (EPU) on the beam dynamics were investigated using active and passive methods. To reduce the tune shift and improve the injection efficiency, dynamic multipole errors were compensated using L-shaped iron shims, which resulted in stable top-up operation for a minimum gap. The skew quadrupole error was compensated using a multipole corrector, which was located downstream of the EPU for minimizing betatron coupling, and it ensured the enhancement of the synchrotron radiation brightness. The investigation methods, a numerical simulation algorithm, a multipole error correction method, and the beam-based measurement results are discussed. [ABSTRACT FROM AUTHOR]

Polarization gating is a popular and widely used technique in biomedical optics to sense superficial tissues (colinear detection), deeper volumes (crosslinear detection), and also selectively probe subsuperficial volumes (using elliptically polarized light). As opposed to the conventional linearly polarized illumination, we propose a new protocol of polarization gating that combines coelliptical and counter-elliptical measurements to selectively enhance the contrast of the images. This new method of eliminating multiple-scattered components from the images shows that it is possible to retrieve a greater signal and a better contrast for subsurface structures. In vivo experiments were performed on skin abnormalities of volunteers to confirm the results of the subtraction method and access subsurface information. [ABSTRACT FROM AUTHOR]

The nonsequential double ionization (NSDI) of atom is revisited by elliptically polarized few-cycle laser pulse with the classical ensemble method. We focus on the events that both electrons emit into the same direction along the long and short axis of the laser polarization plane, and how do the correlated electron momentum spectra of these two events depends on the carrier-envelope-phase (CEP). We first exhibit that the double-ionization probability has a negligible dependence on CEP. Back analysis shows that the ionization dynamics of the second electron are strongly depend on the CEP, which is significantly responsible for the CEP-dependent correlated electron momentum spectra. Besides, the correlated electron momentum spectrum along the long axis of the laser polarization plane reproduces the so-called V-like structure (also called the figurelike structure) observed in experiments [A. Staudte, et al., Phys. Rev. Lett. 99, 263002 (2007); A. Rudenko, et al., Phys. Rev. Lett. 99, 263003 (2007)]. We sort the V-like shape into two regions and find that the different regions exhibit significantly different dynamics behaviors. Simultaneously, we demonstrate that the electron pairs emitted into the same direction along the short axis of the laser polarization plane is a result of the nuclear–electron attraction, and both the nuclear–electron attraction and e–e repulsion significantly contribute to the V-like structure. [ABSTRACT FROM AUTHOR]

The dependence of multiply charged ions on laser ellipticity in methyl iodide clusters with 532 nm nanosecond laser was measured using a time-of-flight mass spectrometer. The intensities of multiply charged ions Iq+(q= 2–4) with circularly polarised laser pulse were clearly higher than those with linearly polarised laser pulse but the intensity of single charged ions I+was inverse. And the dependences of ions on the optical polarisation state were investigated and a flower petal and square distribution for single charged ions (I+, C+) and multiply charged ions (I2+, I3+, I4+, C2+) were observed, respectively. A theoretical calculation was also proposed to simulate the distributions of ions and theoretical results fitted well with the experimental ones. It indicated that the high multiphoton ionisation probability in the initial stage would result in the disintegration of big clusters into small ones and suppress the production of multiply charged ions. [ABSTRACT FROM AUTHOR]

Because of its geophysical interpretation, Earth's polar motion excitation is generally decomposed into prograde (counter-clockwise) and retrograde (clockwise) circular terms at fixed frequency. Yet, these later are commonly considered as specific to the frequency and to the underlying geophysical process, and no study has raised the possibility that they could share features independent from frequency. Complex Fourier Transform permits to determine retrograde and prograde circular terms of the observed excitation and of its atmospheric, oceanic and hydrological counterparts. The total prograde and retrograde parts of these excitations are reconstructed in time domain. Then, complex linear correlation between retrograde and conjugate prograde parts is observed for both the geodetic excitation and the matter term of the hydro-atmospheric excitation. In frequency domain, the ratio of the retrograde circular terms with their corresponding conjugate prograde terms favours specific values: the amplitude ratio follows a probabilistic gamma distribution centred around 1.5 (maximum for 1), and the argument ratio obeys a distribution close to a normal law centred around $$2 \alpha = 160^{\circ }$$ . These frequency and time domain characteristics mean an elliptical polarisation towards $$\alpha ={\sim } 80^{\circ }$$ East with an ellipticity of 0.8, mostly resulting from the matter term of the hydro-atmospheric excitation. Whatsoever the frequency band above 0.4 cpd, the hydro-atmospheric matter term tends to be maximal in the geographic areas surrounding the great meridian circle of longitude $${\sim }80^{\circ }$$ or $${\sim } 260^{\circ }$$ East. The favoured retrograde/prograde amplitude ratio around 1.5 or equivalently the ellipticity of 0.8 can result from the amplification of pressure waves propagating towards the west by the normal atmospheric mode $$\Psi _3^1$$ around 10 days. [ABSTRACT FROM AUTHOR]

ABSTRACT In this letter, L-T slots-loaded dual-band elliptical polarized antenna etched on a single layer substrate is proposed. This antenna is composed from four T-shaped slots near patch boundary and two pair of L-shaped slots etched at patch corner with a rectangular slot located at the center. These combination slots are found out to produce two different frequency bands for LTE and wireless local area network application. The lower band of 2.5-2.69 GHz and the upper band of 5.725-5.85 GHz are controlled by the T-shaped slots and L-shaped slots, respectively. By symmetrically slots and properly positioning the feed position, the proposed antenna exhibits high gain of 6.91 dBi and 7.22 dBi at 2.6 GHz and 5.8 GHz, respectively, even with the compact dimensions of 44 × 44 × 1.6 mm3. Due to the orthogonal surface currents at first and third resonant modes, the proposed antenna gives an elliptical polarization with axial ratios of 7.536 dB at 2.656 GHz and 5.76 dB at 5.8 GHz. The simulation and measurement results of reflection coefficient, gain, and radiation pattern are comparable. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:184-188, 2016 [ABSTRACT FROM AUTHOR]

The two-dimensional optimal velocity model has potential applications to pedestrian dynamics and the collective motion of animals. In this paper, we extend the linear stability analysis presented in a previous paper [A Nakayama et al., Phys. Rev. E. 77, 016105 (2008)] and investigate the effects of particle configuration on the stability of several wave modes of collective oscillations of moving particles. We find that, when a particle moves without interacting with particles that are positioned in a diagonally forward or backward direction, the stable region of the particle flow is completely removed by the elliptically polarized mode. [ABSTRACT FROM AUTHOR]

The effects of the magnetic field and impurity position on the electronic states and nonlinear light absorption in a GaAs pyramidal quantum dot are investigated. The calculations were performed by using the total optical susceptibility for an incident light elliptically polarized along the pyramid growth axis. We proved that: (i) the optical susceptibility can be considerably modified by moving the impurity along the pyramid height; (ii) the enhancement of the magnetic field blueshifts the transition energies and increases the magnitude of the absorption coefficient; (iii) the light dispersion and absorption, as well as the group velocity can be controlled by changing the light intensity and its ellipticity parameter, without supplementary geometrical manipulations. [ABSTRACT FROM AUTHOR]

In this paper, we present a hybrid method for improving the imaging quality of objects obscured within a scattering environment by combining multiple elliptical polarized speckle contrast projections with the use of optical clearing agents (OCAs). Elliptically polarized light enables the probing of subsurface volumes, where OCAs decrease light scattering while increasing photons׳ penetration depth through the medium. Experiments were conducted on object sample and prostate cancer cells embedded within ex vivo biological samples (chicken breasts) in reflection configuration. After immersion with OCAs, the medium was irradiated with an elliptically polarized laser beam and multiple polarized speckled images obtained from a lens array were first converted to speckled contrast images and then processed using a self-deconvolution shift-and-add algorithm. The conversion to contrast images and multiple perspectives acquisition was found to emphasize contrast. Analysis of image quality indicated improvement in object visualization by the combination of elliptical polarization and OCAs. This enhanced imaging strategy may advance the development of improved methods in biomedicine field, specifically biomedical tomography. [ABSTRACT FROM AUTHOR]

We experimentally characterized an all-fiber microstructure Mach–Zehnder comb-filter (MZ comb-filter), which based on homemade elliptical multilayer-core fibers (EMCF) and consisted of an EMCF–SMF–EMCF (ESE) structure. To the best of our knowledge, the dual-mode elliptical multilayer-core fiber was the first time to produce and apply in MZ comb filer. The EMCF, in which only two modes could be propagated, can be easier to fabricate a filter with clean comb spectrum than many fibers, such as multimode fibers, thin-core fibers, PCFs and et al. A comb-filter with extinction ratio (∼25 dB) was successfully achieved with an EMCF–SMF–EMCF structure. The wavelengths of the lead-out light shifted with the changing of surrounding refractive indexes (SRI) and temperature. Thus, this MZ comb-filter had potential for improving the SRI and temperature measurement resolutions. A maximum sensitivity of 53.744 nm per refractive index unit (RIU) within a linear range of 1.333–1.383 and 59.875 pm/°C within temperature range of 0–80 °C were experimentally achieved, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] An asymmetric elliptical-hole dual-core photonic crystal fiber was proposed. [•] The transmission spectra of the proposed fiber under hydrostatic pressure have been calculated. [•] The pressure sensitivity of the proposed fiber at different elliptical ratios have been calculated. [•] The pressure sensitivity of the propose fiber as high as 50.6 pm/Mpa were achieved. [•] The propose fiber has higher pressure sensitivity than that of conventional dual-core photonic crystal. [ABSTRACT FROM AUTHOR]

Nonlinear optical rotation of elliptically polarized laser pulses (λ = 532 nm, τFWHM ~ 12 ns) in benzene, toluene and binary (toluene+acetonitrile) solutions of fullerene 70-D5h(6) has been investigated experimentally. High-resolution transmission electron microscope studies of 70-solutions showed stable ball-shaped 70-clusters formation in toluene+acetonitrile mixtures. It has been demonstrated, that the 70-clusters sizes depend on initial concentration of 70, as well as volume fraction of acetonitrile in solvent mixture. The most probable model of 70-clusterization in solutions was proposed. Correlations between the processes of nonlinear rotation of polarization ellipse, change of electronic absorption spectra and 70-clusters formation in solutions have been demonstrated. Physical mechanisms of laser-induced optical activity in 70-solutions have been discussed. The values of the nonlinear Kerr coefficient (n2) and nonlinear susceptibility component of 70-solutions in: toluene, benzene with various polarization ellipticity (θ = 0.2-0.8), and toluene+acetonitrile at different concentrations of 70 for various volume fractions of acetonitrile have been determined. [ABSTRACT FROM AUTHOR]

When circularly polarized (CP) microstrip antennas are bent, the polarization becomes elliptical. We present a simple model that describes the phenomenon. The two linear modes present in a CP patch are modeled separately and added together to produce CP. Bending distorts the almost-spherical equiphase surface of a linearly polarized patch, which leads to phase imbalance in the far-field of a CP patch. The model predicts both the frequency shifting of the axial ratio band as well as the narrowing of the axial ratio beam. Uncontrolled bending is a problem associated especially with flexible textile antennas, and wearable antennas should therefore be designed somewhat conformal. [ABSTRACT FROM AUTHOR]

Abstract: The polarization state of light in the nematic liquid crystal with the applied magnetic field is analyzed. Using the dielectric tensor, we study the correlation of E x and E y , and analyse the different polarization station of light in liquid crystal with applied different magnetic strength. The theoretically calculated results show that a beam of inclined elliptically polarized light can propagate when B is small, the elliptically polarized light can transmit in this liquid crystal when the magnetic field strength is very large. For liquid crystal with ɛ y = ɛ x , the left-hand and right-hand circular polarized light passes through this liquid crystal with the applied magnetic field. Especially, it was found that the wave can stop in the liquid crystal when the magnetic field strength arrives at the decided value. [Copyright &y& Elsevier]

Based on the metasurface composed of C-shaped slit (CSS) antennas, a broadband transmitted terahertz (THz) polarization modulator (TPM) is proposed and experimentally verified. By rotating the designed TPM, the amplitudes and phase difference of the two orthogonal electric components can be tuned, and thus the polarization of the transmitted THz beam is modulated. The linear-to-linear and linear-to-elliptical polarization conversion is realized with the proposed TPM. Numerical simulations are also performed and agree well with the experimental measurements. The proposed concept can be applied to other wavebands simply by varying the structure parameters and the material of the substrate. [ABSTRACT FROM AUTHOR]