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We have studied the effect of chirality of the magnetization precession on the emission and scattering of spin waves from interfaces between ferromagnets with antiparallel magnetization. The need to match the chirality of the magnetization precessions at such interfaces promotes coupling between propagating modes on one side of the interface and evanescent modes on the other. This leads to the following two major effects: (i) an asymmetrical (ultimately, unidirectional) emission of spin waves from such interfaces when they are driven by an elliptically polarized magnetic field, and (ii) a strong (ultimately, complete) suppression of the transmission of spin waves incident upon such interfaces. Our results are relevant to the construction of spin-wave devices and more generally to the interpretation of measurements and numerical simulations in the field of chiral magnonics.

Bright extreme ultraviolet (XUV) sources with elliptical polarization are powerful tools for investigating the electronic and magnetic properties of materials. Here we show that in the regime of relativistic electrons spring, it is possible to generate a source of elliptically polarized attosecond XUV pulses by a circularly polarized laser pulse interacting with near-critical density plasmas. Particle-in-cell simulations indicate that compared with a conventional overdense plasma regime, the attosecond pulse intensity may be increased by up to one order of magnitude in a near-critical density plasma system.

The theory of the ion cyclotron (IC) electrostatic parametric instabilities of plasma, which are driven by the elliptically polarized fast wave (FW) of the finite wavelength, is developed. This theory provides the analytical treatment of the parametric instabilities with wavelengths comparable with the displacements of ions relative to electrons in the FW. The numerical solution of the dispersion equation for a three wave system that contains the IC mode and two beat waves with frequencies equal to the difference of the IC mode frequency and harmonics of the FW is performed. It reveals the parametric IC instability for this wave system with the maximum growth rate for the IC waves with wavelengths comparable with the thermal ion Larmor radius. The anomalous heating rates of ions resulting from the interactions of ions with parametric IC turbulence are determined employing the developed quasilinear theory for the IC quasimode decay instability. The derived results reveal that the experimentally observed anisotropic heating of cold scrape-off layer (SOL) ions may be the result of the interaction of the SOL ions with IC parametric turbulence. However, the IC parametric turbulence is unlikely to be responsible for the experimentally observed bursts of poorly confined suprathermal ions in the SOL of tokamak plasmas.

The polarization control and conversion of electromagnetic waves is of vital importance in many practical applications and experimental systems. For terahertz waves that cover a broad frequency range of 0.3–10 THz, an operation with high spectral tunability is essential, especially for spectroscopic applications. In this paper, we propose a very simple yet efficient experimental apparatus to convert a linearly polarized beam into a circularly polarized or even an elliptically polarized beam, with high efficiency (>90%) and ultrabroad bandwidth (0.3–10 THz) tunability in the terahertz region. The proposed polarization converter, consisting of only a wire-grid polarizer and a mirror, is convenient and flexible to use in the experimental setup in the laboratory. We expect that it can find broad applications in advanced spectroscopy systems like terahertz ellipsometry where an elliptically polarized beam is needed.

Spin-to-orbital angular momentum conversion and orbital angular momentum conservation in the harmonic generation process have been extensively investigated. However, very few studies have focused on the spin angular momentum (SAM) conservation in the nonlinear optical process. Herein, we investigate the SAM characteristics of the second-harmonic waves with weakly focused elliptically polarized vortex beams (EPVBs). It is shown that the chirality of the second-harmonic wave is always opposite to that of the fundamental wave. Moreover, the absolute value of SAM satisfies the conservation law in the second-harmonic process generated by weakly focused EPVBs. The results are in good agreement with the experimental observations.Spin-to-orbital angular momentum conversion and orbital angular momentum conservation in the harmonic generation process have been extensively investigated. However, very few studies have focused on the spin angular momentum (SAM) conservation in the nonlinear optical process. Herein, we investigate the SAM characteristics of the second-harmonic waves with weakly focused elliptically polarized vortex beams (EPVBs). It is shown that the chirality of the second-harmonic wave is always opposite to that of the fundamental wave. Moreover, the absolute value of SAM satisfies the conservation law in the second-harmonic process generated by weakly focused EPVBs. The results are in good agreement with the experimental observations.

We study the storage and flow of energy in a homogeneous magnetized quantum electron plasma that occurs when an elliptically polarized extraordinary electromagnetic wave propagates in the system. Expressions for the stored energy, energy flow, and energy velocity of extraordinary electromagnetic waves are derived by means of the quantum magnetohydrodynamics theory in conjunction with the Maxwell equations. Numerical results show that the energy flow of the high-frequency mode of extraordinary wave is modified only due to the Bohm potential in the short wavelength limit.

The anisotropic optical properties and polarization filtering are investigated for strained M-plane GaN films as a function of the angle of the in-plane polarization vector. Since the c axis of the underlying wurtzite crystal structure lies in the film plane, its symmetry is reduced in comparison to conventional C-plane films, giving rise to an in-plane polarization anisotropy. This anisotropy is further enhanced by the anisotropic compressive in-plane strain, which occurs due to the lattice mismatch between the GaN film and the substrate LiAlO2. In addition to linear birefringence, the film also exhibits linear dichroism, resulting in a polarization filtering of an incident, linearly polarized light beam after transmission. This filtering manifests itself as a rotation of the polarization vector towards the c axis and can be as large as 80°. We compare the measured polarization rotation with calculated values taking into account the birefringence of the GaN film. In the energy range where the filtering i...

The transformation of a circularly polarized electromagnetic source wave in a suddenly created cold magnetized and weakly nonlinear plasma is considered. For the case of longitudinal propagation (a source wave propagating along an external static magnetic field) when the ion motion is neglected, a circularly polarized source wave splits into four longitudinal oscillating modes. In the case of a linearly polarized source wave due to the interaction between its right and left circularly polarized components additional stationary and traveling electron wave modes are created. Amplitude distributions of all created modes are determined in closed form and presented in corresponding diagrams for different values of source wave and electron cyclotron frequencies.

The National Synchrotron Light Source X13 straight section houses two insertion devices: a small-gap undulator (IVUN) and an elliptically polarized wiggler. The low vertical β function at the center of the straight section, where IVUN is located, produces an extremely small vertical source size [full width at half maximum (FWHM)=15.5 μm]. To take advantage of the small source size for a wide range of x-ray microbeam applications, a Kirkpatrick–Baez pair of 10 cm long elliptically figured mirrors, fabricated using a differential-deposition technique, was designed and implemented. A FWHM focused spot size of 3 μm (vertical) by 9 μm (horizontal) was achieved. The performance of this microfocusing system and selected applications are reported.

A 4-m-long elliptically polarizing undulator (EPU5.6) device with an Apple-II structure is installed in the Synchrotron Radiation Research Center storage ring. This is the longest EPU device with an Apple-II structure worldwide. The errors of the magnet construction and the assembly process are among the several factors that can degrade the spectral performance. This study describes the mechanical design concept and construction that reduce magnetic field errors to keep high performance of the magnet. The electron orbit distortion in various polarization radiation modes is discussed with reference to a global feedback system and a feed forward table with following gap and phase. The beam dynamic effects are also investigated when the phase and magnetic gap are changed.

Metasurfaces have opened an effective way to handle the polarization states of electromagnetic waves due to their intrinsic parameters which could be flexibly tailored. In this paper, we present a simple anisotropic metasurface to realize the polarization manipulation of circularly polarized waves with high conversion efficiency in a wide frequency range. The presented simple metasurface can keep the handedness of the reflected waves for circularly polarized incident waves. Both the simulated and experimental results show that the bandwidth of the polarization conversion ratio more than 90% is 7.16 GHz (8.16–15.32 GHz), and the polarization extinction ratio is larger than 15 dB in this frequency range. Because of the simple design and easy fabrication, the designed metasurface can be an excellent candidate for reflection circular polarization conversion.

Based on the theory of the Pancharatnam-Berry phase, we propose a method for simultaneously measuring polarization and the phase of arbitrarily polarized beams by utilizing digital holography. This method requires merely a single-exposure imaging of interference fringes without changing any optical elements and thus greatly simplifies the operation of the measurement process. This method is more suitable for multiple measurements, especially for measuring the time-changing polarization. The conclusion is expected to provide a reference in polarization holography.

The influence of relativistic correction on the propagation properties of a high-frequency range of the elliptically polarized extraordinary electromagnetic (EP-X-EM) waves in the magnetized spin quantum plasma (MSQP) is investigated by a quantum magneto hydrodynamics model. In such a situation, the relativistic effect becomes particularly noticeable in the presence of a very strong external magnetic field B 0 ≥ B Q ≡ 4.4138 × 10 9 T and a highly dense plasma n 0 ≫ n Q ≃ 10 32 m − 3 where BQ and nQ are the quantum critical magnetic field strength and electron density, respectively. For comparing with a non-relativistic regime, a new dispersion relation that extends the classical EP-X-EM waves to the quantum relativistic context is derived. Furthermore, the cut-off and resonance frequencies of this type of waves are also obtained, allowing us to define the pass and stop bands where waves can propagate in the plasma. As a new result of our work, it is found that the relativistic effect can lead to reduc...

Electron cyclotron emission (ECE) can be used to determine the electron temperature profile in magnetized plasmas. The complex structure of the magnetic field configuration in the Large Helical Device (LHD) [M. Fujiwara et al., J. Fusion Energy 15, 7 (1996)] complicates the analysis of the ECE spectrum. The magnetic field is a nonmonotonous function of the radius and has a very large shear. The effects of the magnetic-field shear on the polarization of the ECE spectrum have been numerically and experimentally analyzed. For a high enough density (ne>1.0×1019 m−3) the polarization is found to rotate with the sheared magnetic field, yielding only a negligible mode conversion. Experiments on the polarization have been carried out at LHD. X-mode emission was detected under a specific angle, in agreement with the numerical predictions. The elliptically polarized ECE emission showed a very strong O-mode component (70% of X-mode), that can be attributed to the effect of wall reflections.

We experimentally observe polarization-locked vector solitons in optical fiber. Polarization locked-vector solitons use nonlinearity to preserve their polarization state despite the presence of birefringence. To achieve conditions where the delicate balance between nonlinearity and birefringence can survive, we studied the polarization evolution of the pulses circulating in a laser constructed entirely of optical fiber. We observe two distinct states with fixed polarization. This first state occurs for very small values birefringence and is elliptically polarized. We measure the relative phase between orthogonal components along the two principal axes to be +/-pi/2. The relative amplitude varies linearly with the magnitude of the birefringence. This state is a polarization locked vector soliton. The second, linearly polarized, state occurs for larger values of birefringence. The second state is due to the fast axis instability. We provide complete characterization of these states, and present a physical explanation of both of these states and the stability of the polarization locked vector solitons. (c) 2000 American Institute of Physics.

The absolute flux, polarization properties, and spatial dependence of the intensity of figure-8-undulator radiation were measured by a gas-scattering method. Absolute-flux measurements were in good agreement with calculated values and the angular divergence measured at 6.6 keV was also close to expected value. Polarization measurements showed oscillations of the degree of linear polarization which varied with photon energy, indicating that both horizontal and vertical polarizations were included. In addition, the polarization plane was found to rotate when the vertical observation angle was changed. These polarization characteristics are not observed in other conventional-undulator radiation and thus unique to figure-8-undulator radiation.

The state of polarization of radiation scattered from hot plasma for any given input polarization is obtained by a relativistic derivation. Approximate analytical expressions are obtained for electron temperatures below about 10 keV. The characteristics of the scattered polarization are presented in detail for fully and linearly polarized incident radiation and their implications for the design of experiments are discussed.

The effects of the rotational degrees of freedom in the photodissociation dynamics of diatomic molecules by a chirped laser pulse is studied. In general, the inclusion of rotational degrees of freedom reduces the efficiency of the chirping excitations relative to that found for nonrotating molecules. However, using classical 2D and 3D rotating Morse oscillator models we demonstrate that field polarization can cause dramatic enhancements of the dissociation probabilities, with circularly polarized chirped pulses inducing dissociation in rotating molecules almost as efficiently as that previously seen for nonrotating Morse oscillators. We suggest reasons for such improvement in efficiency and discuss the validity of the bucket dynamics model for rotating Morse oscillators.

The tunneling dynamics of a dissipative two-level system that is strongly driven by elliptically polarized electric fields is investigated. The dissipative dynamics is governed within the noninteracting-blip-approximation for the stochastic forces by a generalized master equation (GME). With the focus being on viscous friction, we compare exact numerical solutions of the GME with analytical approximations to both the transient and the asymptotic, long-time periodic dynamics. Novel phenomena are identified: These are a selective control on localization (or, as well, on delocalization) of the tunneling dynamics, or the inversion of an initially induced localization by a static bias via multiphoton-assisted tunneling. These effects can be selectively tuned as a function of the eccentricity parameter p=E????/E???? of corresponding field amplitudes. In particular, the case of a circularly polarized driving field with p=±1 yields a dramatic enhancement of the relaxation rate at resonances, when an integer multiple of the angular driving frequency matches the asymmetry energy induced by a static bias.

Chirality may provide the coupling, and hence the conversion, between two eigen polarization modes: TE and TM modes. In this paper an analysis of mode interaction in chirowaveguides is realized, taking into account longitudinal components of polarization currents. Special consideration is given to so‐called induced polarization effects which are caused by abrupt discontinuities of longitudinal polarization currents on the boundary of chiral–nonchiral media. Because of induced polarization effects, an asymmetry in mode coupling may take place. The method of investigation may be a powerful tool for the analysis of mode interactions due to both material and geometric effects.

An elliptically polarized pump-probe spectroscopy is developed. A theoretical model is derived from the rate equations of two-level system with small signal approximation to describe the experimental signal of the spectroscopy. The spectroscopy eliminates the systematic errors between theories and experimental results in present circularly polarized pump-probe spectroscopy, and is implemented easily in experiments. The initial degree of spin polarization of carriers in an excited state can be extracted by means of the spectroscopy, which is an important parameter in the investigation of spatial transport of spin polarization. The electron-spin relaxation in GaAs quantum wells is studied by using this spectroscopy.

Femtosecond optical pump-probe experiments were performed upon a Ni(720 A)/Si(100) sample in the polar geometry with the pump beam close to normal incidence. A signal due to the ultrafast demagnetization effect was observed when the pump pulse was linearly polarized. When the pump was elliptically polarized, additional peaks were observed at zero time delay, resulting from the specular inverse Faraday effect (SIFE) and the specular optical Kerr effect (SOKE). By comparing measurements made with different pump helicities, the SIFE and SOKE peaks and the demagnetization signal were found to superpose in a linear fashion. From the dependence of the peak height upon the pump polarization, values of χxxyy=(1−3i)×10−10 rad cm3 erg−1 and χxyyx=(−9+2i)×10−12 rad cm3 erg−1 were deduced for the nonvanishing components of the local cubic susceptibility tensor. For applied fields less than the saturation value, the sudden reduction of the thin film demagnetizing field leads to an imbalance of the torques acting upon ...

A practical procedure is described to measure photofragment μ‐v‐j correlations using polarized 1+n′ resonance‐enhanced multiphoton ionization with a time‐of‐flight mass spectrometer detector. Following the theory of Dixon [R. N. Dixon, J. Chem. Phys. 85, 1866 (1986)], the correlations are expressed as the moments of a bipolar harmonic expansion of the correlated angular distribution of photofragment velocity and angular momentum (v and j) about the parent molecule transition dipole, μ. At a fixed detection geometry and on a single rotational transition, polarization control of the dissociating or probing light permits selective determination of targeted moments of the bipolar harmonic expansion. The velocity‐dependent spherical tensor moments of the angular momentum distribution depend upon these bipolar moments and are given for a general experimental geometry and for general elliptical polarization of the probing light. Several practical experimental geometries are described that isolate and measure tar...

An ultra-wideband and high-efficiency polarization rotator based on a metasurface is proposed in this paper. The unit cell of the proposed polarization rotator consists of two pairs of L-shaped metallic patches printed on a substrate, which is backed by a metallic ground and covered by a superstrate. The superstrate is composed of a dielectric layer and a pair of L-shaped metallic patches printed on the dielectric layer. The proposed polarization rotator can rotate the polarization of linearly polarized electromagnetic (EM) wave to its orthogonal counterpart after reflection when the incident EM wave is y-/x-polarized. Simulated results show that the polarization rotator can perform 90° polarization rotation with very high efficiency at seven different frequencies and achieve a polarization conversion ratio higher than 0.9 in the frequency range of 7.8–34.7 GHz at normal incidence. Good agreement between the experimental results and simulated ones has been obtained.

The dispersion properties of elliptically polarized electromagnetic (EM) waves in a magnetized electron-positron-pair (EP-pair) plasma are studied with the effects of particle dispersion associated with the Bohm potential, the Fermi degenerate pressure, and the exchange-correlation force. Two possible modes of the extraordinary or X wave, modified by these quantum effects, are identified and their propagation characteristics are investigated numerically. It is shown that the upper-hybrid frequency, and the cutoff and resonance frequencies are no longer constants but are dispersive due to these quantum effects. It is found that the particle dispersion and the exchange-correlation force can have different dominating roles on each other depending on whether the X waves are of short or long wavelengths (in comparison with the Fermi Debye length). The present investigation should be useful for understanding the collective behaviors of EP plasma oscillations and the propagation of extraordinary waves in magnetized dense EP-pair plasmas., Comment: 7 pages, 4 figures

We investigate magnetization states of a canted antiferromagnetic YFeO3 by using terahertz (THz) time-domain spectroscopy under a variation of an external magnetic field. As a quasi-ferromagnetic mode near 0.3 THz is excited by the magnetic field of the THz pulse, a precession of the magnetic moment and its induction decay radiate the THz wave. Since oppositely aligned magnetic domains emit the circularly/elliptically polarized THz waves with opposite helicities, a detection of specific polarization of the THz wave shows a clear hysteresis behavior in good agreement with a magnetization curve obtained as a function of the applied magnetic field. Furthermore, time-domain measurement of excited magnetic moment can provide direct information about the magnetization decay dynamics.

We made a new polarization analyzing system for measuring a rotation of major axis of elliptical polarization in x‐ray magnetic resonant scattering. This system, based on a two‐axis diffractometer, is characterized by introducing a 45° linearly polarized x‐ray incident beam. Design and performance of the system are described. The rotation can be measured with precision of 0.2°–0.3° at the vicinity of Gd L3‐absorption edge where the maximum rotation is about −2°.

We present a unique method for converting circularly polarized light into radially and azimuthally polarized beams. The method is based on the use of computer-generated space-variant subwavelength metal stripe gratings. The elements were realized on GaAs substrates and produced beams with high polarization purity at a wavelength of 10.6 μm. As a result of the conversion, the beams also undergo space-variant phase modification, which has an effect on their propagation. We demonstrate the effect experimentally, and calculate it using full space-variant polarization and phase analysis based on rigorous coupled-wave analysis and Jones calculus.

The photoionization process NO A 2Σ+ (v=0, N=22)→NO+ X 1Σ+ (v+=0, N+)+e− is studied with sufficient photoelectron energy resolution that the photoelectron angular distributions (PADs) associated with individual rotational levels N+ of the ion are determined. By ionizing with left and right circularly polarized light and observing the change in the rotationally resolved PADs, we can deduce all dynamical information, including the signs of the relative phase shifts of the photoelectron partial waves. This information constitutes the first complete description of the photoionization of a molecule. We discuss the consistency of our dynamical parameters with the Rydberg series of NO. We present a general formalism for (1+1’) resonance‐enhanced multiphoton ionization (REMPI) PADs for rotationally resolved ion states using linearly polarized light for excitation and elliptically polarized light for ionization. Based on the dynamical parameters determined from our fit, we use this formalism to predict the total s...

Interaction of elliptically polarized laser radiation with plasma produced from a solid target generates magnetic fields simultaneously along axial and transverse directions. The axial magnetic field induces the plane of polarization of the incident laser beam to rotate due to the Faraday effect. Numerically the Faraday rotation has been calculated for interaction of Nd glass laser (λ=1.06 μm) in the subdense plasma in which the plasma density, temperature, and self‐generated magnetic field vary in the axial direction.

This paper extends the McClain formulation of two‐photon absorption to show what observables can be independently determined in an emission experiment for which incident and scattered photon polarizations are resolved. Interelectronic state coupling contributions and quantum interference can be extracted from the polarized emission spectrum by determining the three linearly independent contributions to the scattering intensity. This enhances the value of polarized emission spectroscopy as a tool for understanding transitions between coupled electronic states that occur during dissociation dynamics. We demonstrate that the three linearly independent contributions to the polarized emission spectrum can be determined by performing three polarization experiments, at least one of which must involve circularly polarized light. Furthermore, the three polarization experiments must be performed at a scattering angle other than π/2. We also present sample calculations on a model of the methyl iodide system which se...

A polarizing undulator has been constructed utilizing crossed and retarded magnetic fields that can provide arbitrary polarized radiation. The absolute brightness and polarization characteristics have been studied in the visible region from 350–700 nm at 230 MeV of stored electron energy by varying the observation angle θ. Any desired elliptically polarized radiation was obtainable by adjusting the retardation between the two pairs of magnet arrays.

A complete polarization analysis has been successfully achieved for synchrotron radiation beams in the vacuum ultraviolet and soft x‐ray regions using a reflection polarimeter. The Stokes parameters, which provide a full description of the polarization state of light, were experimentally determined along with three polarizing quantities of the polarimeter. The present result indicates the possibility of a simultaneous determination of the optical constants of mirror materials through polarization analyses.

A theory is presented to describe quantitatively how nuclear spin polarization can be induced in a metal by a dc electric bias current driven through the sample. The bias current is spin polarized by passing through a thin ferromagnetic film in interfacial contact with the sample, with the polarization axis determined by the magnetization orientation of the ferromagnetic layer. The nuclear spins are polarized due to spin angular momentum transfer from the electrons to the nuclei mediated by the contact hyperfine interaction. Upon reversing the polarity of the bias current, the sign of the nuclear polarization is reversed. Unlike other methods of dynamic nuclear polarization, spin-injected dynamic nuclear polarization is a zero frequency technique that in principle does not require an applied magnetic field.

It is shown that elliptically polarized short laser pulses in a magnetized plasma can generate upper-hybrid wakefields. The potential profiles of the latter are obtained for given laser beam envelopes. The upper-hybrid wakefields can accelerate electrons to high energy due to the surfatron process.

A linear stability analysis of the collective Raman interaction in a free‐electron laser with combined planar wiggler and axial guide magnetic fields is presented. The analysis involves a perturbation of the cold‐fluid model of the interaction about the single‐particle trajectories in the combined external fields, and the complete dispersion equation for a monoenergetic beam is obtained. In contrast to the case of a helical wiggler field in which the interaction excites a right‐hand circularly polarized wave, the interaction for a planar wiggler and an axial guide field is with an elliptically polarized wave that contains both the left‐ and right‐hand circular components. However, the results indicate that many facets of the interaction are analogous to those found with helical wiggler. In particular, both the transverse velocity and the growth rate of the instability tend to increase near the resonance at which the Larmor and wiggle periods coincide. In addition, a negative‐mass regime is found in which the axial electron velocity increases with decreasing beam energy, which drives the beam space‐charge modes unstable.

We demonstrate an all-optical (4)He atomic magnetometer experimental scheme based on an original Bell-Bloom configuration. A single intensity-modulated linearly polarized laser beam is used both for generating spin polarization within a single (4)He vapor and probing the spin precessing under a static magnetic field. The transmitted light signal from the vapor is then phase-sensitively detected at the modulation frequency and its harmonics, which lead to the atomic magnetic resonance signals. Based on this structure, a liquid crystal is added in our magnetometer system and constitutes a polarization rotator. By controlling the voltage applied on the liquid crystal, the light linear polarization vector can be kept perpendicular with the ambient magnetic field direction, which in turn provides the maximum resonance signal amplitude. Moreover, the system exhibits a magnetic-field noise floor of about 2pT/√Hz, which is not degraded due to the presence of the liquid crystal and varying magnetic field direction. The experiment results prove that our method can eliminate the dead-zone effect, improve the system spatial isotropy, and thus be suitable in mobile applications.

In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal monochromator is used upstream from the sample to select the appropriate photon energy, and a horizontally deflecting X-ray polarization analyzer, consisting of a perfect single crystal with a Bragg reflection at Bragg angle of approximately 45°, is placed downstream from the sample to measure the resulting rotation of the X-ray polarization. However, if the experiment is performed on a synchrotron bending-magnet beamline, then the elliptical polarization of the X-rays out of the electron orbit plane affects the shape of the output beam. Also, because the monochromator introduces a correlation between vertical position and photon energy to the X-ray beam, the polarization analyzer does not select the entire beam, but instead selects a diagonal stripe, the slope of which depends on the Bragg angles of the monochromator and the polarization analyzer. In the present work, the final background intensity distribution is calculated analytically because the phase space sampling methods normally used in ray traces are too inefficient for this setup. X-ray Birefringence Imaging data measured at the Diamond Light Source beamline B16 agree well with the theory developed here.

In spite of the importance of anisotropic circular dichroism, in practice, it is difficult to get rid of the artifacts that arise from the imperfection of the circular polarization. Undesirable linear dichroism, interference of two orthogonal polarization states, and linear birefringence prevent us from making accurate measurements. We propose a theoretical method for evaluating the contributions of the first two, which are thought to be the main artifacts when specimens are not thick enough. Using the time-dependent perturbation theory and taking into account the direction of light propagation toward an orientationally fixed molecule, we formulated the transition probability of systems perturbed by arbitrarily polarized light and the absorption difference associated with two kinds of polarized light. We also formulated, as an extension of the dissymmetry factor of circular dichroism, a newly defined dissymmetry factor associated with two arbitrary polarization states. Furthermore, we considered a mixed-state of photon ensemble in which polarization states distribute at a certain width around a certain average. Although the purity of polarization and ellipticity does not correspond immediately, by considering the mixed state it is possible to treat them consistently. We used quantum statistical mechanics to describe the absorption difference for two kinds of photon ensembles and applied the consequent formula to examine the reported experimental results of single-molecule chiroptical responses under discussion in the recent past. The artifacts are theoretically suggested to be sensitive to the incident direction of elliptically polarized light and to the oriented systems, the ellipticity, and the orientation of ellipse. The mixed state has little, if any, effect when the polarization state distribution is narrow.

Analyzing the polarization of a circularly polarized light is a critical issue. We have fabricated a spiral nano-structure on the Au film by using focused ion beam etching technique. The fabricated structure can be used as a plasmonic circular polarization analyzer. By designing the relative orientation of two nano-apertures in the spiral structural unit, the propagation direction of the surface plasmon polaritons excited by circularly polarized light of opposite handedness can be controlled. Therefore, the spiral structure could be used to accurately determine the helicity of the excited circularly polarized light. Based on the results of scanning near-field optical microscopy, the obtained circular polarization extinction ratio of this structure was above 500. This structure can be used for a flexible detecting size and a very wide spectrum.

An analytical theory is developed for studying the phenomenon of generation of harmonics by the propagation of an obliquely incident, circularly polarized laser beam in homogeneous, underdense plasma. The amplitudes of second and third harmonic radiation as well as detuning distance have been obtained and their variation with the angle of incidence is analyzed. The amplitude of harmonic radiation increases with the angle of incidence while the detuning distance decreases, for a given plasma electron density. It is observed that the generated second and third harmonic radiation is linearly and elliptically polarized, respectively. The harmonic radiation vanishes at normal incidence of the circularly polarized laser beam.

The THz-radiation power from bulk InAs irradiated with femtosecond optical pulses is significantly enhanced and reaches 650 μW in a 1.7-T magnetic field with 1.5-W excitation power. The THz-radiation power is related almost quadratically both to the magnetic field and excitation laser power. We have also found that the power of the THz-radiation from an InAs sample in a magnetic field is over one order of magnitude higher than that from GaAs. Additionally, a dramatic change of ellipticity is observed, and the spectra of the horizontal and vertical polarization components are found to differ.

Linearly polarized soft x-rays are converted to elliptical polarization at the Fe L3 line (707 eV) using magnetic circular dichroism (MCD) on transmission through thin Fe films. A linear polarizer measured the transmitted polarization at different incidence angles to vary as expected from a model for in-plane magnetization, and also to exhibit a weak MCD effect at normal incidence interpreted to originate from perpendicular interface anisotropy. An MCD signal from a downstream Fe film was produced by switching the helicity of x-rays transmitted through an upstream circular polarizer. Practical considerations for optimizing the production of circular polarization are discussed, and synchrotron radiation applications using these circular polarizing filters are suggested.

A system of diffracting perfect crystals for the generation of variable, elliptically polarized x rays was tested at the Cornell High Energy Synchrotron Source under the conditions of a standard undulator source. The phase retarding optical component was a 4‐bounce, Ge(220) Bragg reflection channel‐cut crystal. The full polarization state of the output beam, including the circular polarization purity P3, was determined using the multiple‐beam Bragg diffraction technique. In addition to measuring the optics’ efficiency, the ability to scan the system in energy, while frequently reversing the circular helicity, was demonstrated at the vicinity of the Fe K edge at 7.1 keV. The setup was applied to a circular magnetic x‐ray dichroism measurement.

We propose a novel technique to directly transform a linearly polarized Gaussian beam into vector-vortex beams with various spatial patterns. Full high-quality control of amplitude and phase is implemented via a Digital Micro-mirror Device (DMD) binary holography for generating Laguerre-Gaussian, Bessel-Gaussian, and helical Mathieu–Gaussian modes, while a radial polarization converter (S-waveplate) is employed to effectively convert the optical vortices into cylindrically polarized vortex beams. Additionally, the generated vector-vortex beams maintain their polarization symmetry after arbitrary polarization manipulation. Due to the high frame rates of DMD, rapid switching among a series of vector modes carrying different orbital angular momenta paves the way for optical microscopy, trapping, and communication.

The propagation of an elliptically polarized intense laser pulse in an unmagnetized collisionless uniform plasma is considered. A multiple scale perturbation theory is employed to show that in a weakly relativistic regime, evolution of the components of vector potential is governed by two coherently coupled nonlinear Schrodinger (NLS) equations. A set of equations describing the evolution of Stokes parameters is derived within the continuous wave approximation and the dynamics of components of field amplitude is studied. The polarization dynamics of a pulse is investigated by means of numerical solution of the coupled NLS equations. A detailed analysis of vector modulational instability is presented and the possibility for occurrence of various kinds of vector solitary waves is addressed.

Besides intensity and direction, the polarization of an electromagnetic wave provides characteristic information on the crossed medium. Here, we present two methods for the determination of the polarization state of x rays by polarizers based on anomalous transmission (Borrmann effect). Using a polarizer-analyzer setup, we have measured a polarization purity of less than 1.5 × 10−5, three orders of magnitude better than obtained in earlier work. Using the analyzer crystal in multiple-beam case with slightly detuned azimuth, we show how the first three Stokes parameters can be determined with a single angular scan. Thus, polarization analyzers based on anomalous transmission make it possible to detect changes of the polarization in a range from degrees down to arcseconds.

A merged vector grating, which is holographically fabricated in an anisotropic medium by irradiation with interference light with intensity modulation and polarization modulation, was designed to detect the polarization of light. The merged vector grating is recorded by the interference of two elliptically polarized beams with equal intensities, parallel azimuths, equal ellipticities, and different directions of rotation. We clarified theoretically that the Stokes parameters of the incident light beam are described by the diffraction efficiency of the merged vector grating. Also, to apply this property to formation of a polarimeter without any moving parts or mechanisms, two merged vector gratings with different grating vectors were recorded in a photocrosslinkable polymer liquid crystal film by angle-multiplexed holography. By investigation of the diffraction properties of the gratings obtained, we demonstrated the applicability of the merged vector gratings for use in polarimetry.

Development of quantum electrodynamical (QED) cascades in a standing electromagnetic wave for circular and linear polarizations is simulated numerically with a 3D PIC-MC code. It is demonstrated that for the same laser energy the number of particles produced in a circularly polarized field is greater than in a linearly polarized field, though the acquiring mean energy per particle is larger in the latter case. The qualitative model of laser-assisted QED cascades is extended by including the effect of polarization of the field. It turns out that cascade dynamics is notably more complicated in the case of linearly polarized field, where separation into the qualitatively different “electric” and “magnetic” regions (where the electric field is stronger than the magnetic field and vice versa) becomes essential. In the “magnetic” regions, acceleration is suppressed, and moreover the high-energy electrons are even getting cooled by photon emission. The volumes of the “electric” and “magnetic” regions evolve periodically in time and so does the cascade growth rate. In contrast to the linear polarization, the charged particles can be accelerated by circularly polarized wave even in “magnetic region.” The “electric” and “magnetic” regions do not evolve in time, and cascade growth rate almost does not depend on time for circular polarization.

We demonstrate the generation and control of elliptically polarized terahertz (THz) waves from air plasma produced by circularly polarized few-cycle laser pulses. Experimental and calculated results reveal that electric field asymmetry in rotating directions of the circularly polarized few-cycle laser pulses produces the enhanced broadband transient currents, and the phase difference of perpendicular laser field components is partially inherited in the generation process of THz emission. The ellipticity of the THz emission and its major axis direction are all-optically controlled by the duration and carrier-envelope phase of the laser pulses.