Showing papers on "Polarization rotator published in 2009"
TL;DR: The net effect of the polarization field strength on the resultant nuclear spin states is shown to be predictable but complex.
Abstract: When parahydrogen adds to a metal template containing a substrate of interest, the substrate and parahydrogen become coupled, and polarization is shared between the two without the incorporation of the parahydrogen into the substrate. A mechanism for this polarization transfer is presented in which the transfer is propagated through the scalar couplings. At zero field, polarization is transferred between two-, three-, and four-spin zero quantum states, but no single spin magnetization is created. The interplay between the chemical shift evolution and the evolution under scalar coupling at non-zero field generates additional longitudinal spin order and now includes single spin longitudinal z-magnetization. The additional chemical shift interaction introduces a field dependency to the nuclear spin states of the polarized substrate. The net effect of the polarization field strength on the resultant nuclear spin states is shown to be predictable but complex.
183 citations
TL;DR: It is shown here that the plasma-emitted half-cycle THz radiation directly reflects the two-dimensional trajectories of the electrons through polarization sensitive THz emission spectroscopy, providing a new means of coherently controlling the polarization of light at THz frequencies.
Abstract: The dynamics of ionized electrons in a plasma can be controlled by synthetic optical fields composed of the fundamental and the second harmonic of femtosecond optical pulses with an arbitrary phase and polarization. We show here that the plasma-emitted half-cycle THz radiation directly reflects the two-dimensional trajectories of the electrons through polarization sensitive THz emission spectroscopy. As a result, we find that the THz polarization smoothly rotates through 2pi radians as the relative phase between the two pulses is adjusted, providing a new means of coherently controlling the polarization of light at THz frequencies.
144 citations
TL;DR: In this article, the Stokes parameters from the last scattering surface for an oscillating and a monotonic decreasing pseudoscalar field were computed analytically and numerically.
Abstract: We discuss the rotation of the linear polarization plane and the production of circular polarization generated by a cosmological pseudoscalar field. We compute analytically and numerically the propagation of the Stokes parameters from the last scattering surface for an oscillating and a monotonic decreasing pseudoscalar field. For the models studied in this paper, we show the comparison between the widely used approximation in which the linear polarization rotation angle is constant in time and the exact result.
114 citations
TL;DR: The possibility of transformation of the spatial polarization distribution in the measured spatial intensity distribution for determining the degree of correlation of superposing waves, linearly polarized in the plane of incidence, is shown.
Abstract: A new approach is proposed for estimating the degree of coherence of optical waves. The possibility of transformation of the spatial polarization distribution in the measured spatial intensity distribution for determining the degree of correlation of superposing waves, linearly polarized in the plane of incidence, is shown.
92 citations
TL;DR: The condition for obtaining polarization pulling by exploiting the stimulated Raman scattering is investigated, which is most suitable for optical communications thanks to its large gain bandwidth.
Abstract: The interest towards passive control of the light polarization through nonlinear effects has been stimulated by recent works: in particular a polarization pulling effect has been obtained by means of stimulated Brillouin scattering. Here we investigate the condition for obtaining polarization pulling by exploiting the stimulated Raman scattering, which is most suitable for optical communications thanks to its large gain bandwidth. The role of the polarization-dependent Raman amplification and of the random fiber birefringence is clarified by theoretical considerations and numerical simulations starting from the vector theory of the Raman effect in optical fiber. Experiments carried out with a 1571-nm signal and high-power 1486-nm pump evidence the Raman-induced polarization pulling.
89 citations
TL;DR: In this article, the authors reported the results of parsec-scale, multifrequency Very Long Baseline Array observations of the core region of 3C-279 in Stokes I, linear polarization, and circular polarization.
Abstract: We report the results of parsec-scale, multifrequency Very Long Baseline Array observations of the core region of 3C 279 in Stokes I, linear polarization, and circular polarization. These full polarization spectra are modeled by radiative transfer simulations to constrain the magnetic field and particle properties of the parsec-scale jet in 3C 279. We find that the polarization properties of the core region, including the amount of linear polarization, the amount and sign of Faraday rotation, and the amount and sign of circular polarization can be explained by a consistent physical picture. The base of the jet, component D, is modeled as an inhomogeneous Blandford-Konigl style conical jet dominated by a vector-ordered poloidal magnetic field along the jet axis, and we estimate its net magnetic flux. This poloidal field is responsible for the linear and circular polarization from this inhomogeneous component. Farther down the jet, the magnetic field in two homogeneous features is dominated by local shocks and a smaller fraction of vector-ordered poloidal field remains along the jet axis. This remaining poloidal field provides internal Faraday rotation which drives Faraday conversion of linear polarization into circular polarization from these components. In this picture, we find the jet to be kinetically dominated by protons with the radiating particles being dominated by electrons at an approximate fraction of 75%, still allowing the potential for a significant admixture of positrons. Based on the amounts of Faraday conversion deduced for the homogeneous components, we find a plausible range for the lower cutoff in the relativistic particle energy spectrum to be 5 γ l 35. The physical picture described here is not unique if the observed Faraday rotation and depolarization occur in screens external to the jet; however, we find the joint explanation of linear and circular polarization observations from a single set of magnetic fields and particle properties internal to the jet to be compelling evidence for this picture.
87 citations
TL;DR: The utility of the method uses a Sagnac interferometer that incorporates a spatial light modulator to combine beams that possess oppositely charged phase vortices in order to achieve the desired polarization vortex is demonstrated.
Abstract: We present a method for producing laser beams of nonuniform polarization where the polarization direction rotates on a trajectory about the beam propagation direction. Our method uses a Sagnac interferometer that incorporates a spatial light modulator to combine beams that possess oppositely charged phase vortices in order to achieve the desired polarization vortex. We demonstrate the utility of our method by producing polarization vortices characterized by a fractional index, and we compare the results with calculations of the expected fields.
55 citations
TL;DR: In this paper, a polarization sensitive terahertz detection method was proposed to measure both orthogonal components of the teraspectral electric field of the material and allow for the study of polarization dependent properties of materials.
Abstract: We present a polarization sensitive terahertz detection method which is able to measure both orthogonal components of the terahertz electric field. It allows for the study of polarization dependent properties of materials. Azimuthal angle dependent transmittance in 0.2–2.6 THz frequency region for crystalline quartz is measured. Polarized terahertz transmission spectroscopy shows that birefringence can result in transmission minima. This work suggests that polarization sensitive detection is effective for removing fake absorption features caused by material birefringence.
51 citations
TL;DR: In this article, a vertical cavity surface-emitting laser (VCSEL) is shown to support spatially localized structures with linear polarization, orthogonal to the principal polarization.
Abstract: We show that a $40\text{\ensuremath{-}}\ensuremath{\mu}\mathrm{m}$-diameter vertical-cavity surface-emitting laser (VCSEL) is capable of supporting spatially localized structures with linear polarization, orthogonal to the principal polarization. The VCSEL is biased above the lasing threshold and emits a well-defined linear polarization (principal polarization). A holding beam with orthogonal polarization is injected into the cavity, and a localized structure is spontaneously switched on. The orthogonally polarized localized structure is shown to be bistable when the injection current is varied. Numerical results based on a rate equation model support the experimental findings.
50 citations
TL;DR: In this paper, the spontaneous formation of a stochastic polarization in exciton-polariton Bose-Einstein condensates in planar microcavities under pulsed excitation was demonstrated.
Abstract: We demonstrate theoretically the spontaneous formation of a stochastic polarization in exciton-polariton Bose-Einstein condensates in planar microcavities under pulsed excitation. Below the threshold pumping intensity (dependent on the polariton lifetime), the average polarization degree is close to zero, while above threshold the condensate acquires a polarization described by a (pseudospin) vector with random orientation, in general. It is shown that the polariton-polariton interaction leads to suppression of the linear polarization degree of the condensate due to the self-induced Larmor precession of the pseudospin. We establish the link between the second-order coherence of the polariton condensate and the distribution function of its polarization. We examine also the mechanisms of polarization dephasing and relaxation.
49 citations
Patent•
09 Feb 2009TL;DR: In this article, the authors present a model of a stereoscopic digital image projector with a plurality of light modulation assemblies, each comprising at least one solid-state light source energizable to provide illumination having a first polarization axis; a polarization rotator disposed in the path of the polarized illumination from the solid state light source(s) and actuable to controllably rotate the polarization axis from one solid state to a second polarized axis.
Abstract: A stereoscopic digital image projector includes (a) a plurality of light modulation assemblies, each comprising: (i) at least one solid-state light source energizable to provide illumination having a first polarization axis; (ii) a polarization rotator disposed in the path of the polarized illumination from the solid-state light source(s) and actuable to controllably rotate the polarization axis from the solid-state light source(s) to a second polarized axis; (iii) a micro-electromechanical spatial light modulator in the path of the polarized illumination and energizable to modulate the polarized illumination to form a first modulated light from illumination of the first polarization state and to form a second modulated light from illumination of the second polarization state; and (b) a synchronizing means to temporally control the polarization rotation to match the appropriate image data on the spatial light modulator; and (c) projection optics for directing the first and second modulated light toward a display surface.
TL;DR: In this article, a distributed stress sensor with a white-light scanning interferometer is used to detect stress distribution by analyzing polarization mode coupling caused by forces exerted on PMFs (polarization maintaining fibers).
TL;DR: In this paper, a SiGe-based light emitting diode from the remanent state of a perpendicularly magnetized ferromagnetic contact was used for electrical spin injection into an alumina tunnel barrier from a Co/Pt thin film exhibiting strong out-of-plane anisotropy.
Abstract: In this letter, we show efficient electrical spin injection into a SiGe based \textit{p-i-n} light emitting diode from the remanent state of a perpendicularly magnetized ferromagnetic contact. Electron spin injection is carried out through an alumina tunnel barrier from a Co/Pt thin film exhibiting a strong out-of-plane anisotropy. The electrons spin polarization is then analysed through the circular polarization of emitted light. All the light polarization measurements are performed without an external applied magnetic field \textit{i.e.} in remanent magnetic states. The light polarization as a function of the magnetic field closely traces the out-of-plane magnetization of the Co/Pt injector. We could achieve a circular polarization degree of the emitted light of 3 % at 5 K. Moreover this light polarization remains almost constant at least up to 200 K.
TL;DR: A liquid-crystal voltage-controlled linear polarizer is demonstrated using two LC retarders stacked with two quarter-wave plates and an intermediate linear absorptive polarizer that has a potential application in high-dynamic-range polarimetric imaging.
Abstract: A liquid-crystal (LC) voltage-controlled linear polarizer is demonstrated using two LC retarders stacked with two quarter-wave plates and an intermediate linear absorptive polarizer. The device was examined experimentally using unpolarized light and was found to be in accordance with the theoretical prediction. Under certain conditions the device acts as a polarization rotator with possibility for simultaneous amplitude modulation. Hence it has a potential application in high-dynamic-range polarimetric imaging.
TL;DR: The supercontinuum generated with a linearly polarized near-IR pump in rotated calcium fluoride is shown to have intrinsic intensity and polarization modulations and is extended deep into the ultraviolet with a frequency doubled pump to serve as an new source to probe the region where most molecular photochemistry occurs.
Abstract: The supercontinuum generated with a linearly polarized near-IR (775 nm) pump in rotated calcium fluoride is shown to have intrinsic intensity and polarization modulations. To mask the rotation of the crystal plate, we circularly polarize the pump and find greatly improved output parameters for the generated white light: intensity fluctuations of 0.5% limited only by pump laser stability, and a circular polarization state-matching that of the pump-over the entire visible spectrum. This polarization conservation allows the return of the supercontinuum to a linear polarization state or to a pair of linearly polarized beams with correlated intensity fluctuations. We were also able to extend the supercontinuum source deep into the ultraviolet with a frequency doubled (387 nm) pump, to serve as an new source to probe the region where most molecular photochemistry occurs.
TL;DR: In this article, an analysis of the polarization of terahertz (THz) radiation from a laser-induced plasma source is presented, where the main focus lies on the dependence of THz polarization on the polarization and relative phase of the incident fundamental and second-harmonic pulses.
Abstract: An analysis of the polarization of terahertz (THz) radiation from a laser-induced plasma source is presented. THz emission is achieved by mixing a laser pulse with its second harmonic after focusing through a β-BaB2O4 (β-BBO) crystal. Numerical calculations, based on the nonlinear four-wave mixing model and the microscopic polarization model, are compared with experimental results. The main focus lies on the study of the dependence of THz polarization on the polarization and relative phase of the incident fundamental and second-harmonic pulses. We show that the modulation of the fundamental pulse by the BBO crystal has to be taken into account in order to describe experimental observations. By including the finite extension of the plasma and considering cross- and self-phase modulation of the two-color pump pulse, we are able to explain the observed ellipticity of the THz pulse as well as the orientation of the polarization axis.
TL;DR: In this paper, the authors demonstrate optical control of the polarization eigenstates of a neutral quantum dot exciton without any external fields by varying the excitation power of a circularly polarized laser in microphotoluminescence experiments on individual InGaAs quantum dots.
Abstract: We demonstrate optical control of the polarization eigenstates of a neutral quantum dot exciton without any external fields. By varying the excitation power of a circularly polarized laser in microphotoluminescence experiments on individual InGaAs quantum dots we control the magnitude and direction of an effective internal magnetic field created via optical pumping of nuclear spins. The adjustable nuclear magnetic field allows us to tune the linear and circular polarization degree of the neutral exciton emission. The quantum dot can thus act as a tunable light polarization converter.
TL;DR: In this paper, the authors theoretically and experimentally investigated polarization insensitive all-optical wavelength conversion for polarization multiplexing signal based on orthogonal pump four-wave mixing in nonlinear optical fiber.
Abstract: We have theoretically and experimentally investigated polarization insensitive all-optical wavelength conversion for polarization multiplexing signal based on orthogonal pump four-wave mixing in nonlinear optical fiber. After wavelength conversion based on 1 km high-nonlinear optical fiber with polarization insensitivity, the power penalties of 2.5 Gbit/s optical OOK intensity and 10 Gbit/s differential phase-shift keying orthogonal signals are less than 0.5 and 0.8 dB, respectively.
TL;DR: It is shown that, for 3D random electromagnetic fields that are created by optical systems from a partially polarized plane wave, two different definitions of the 3D degree of polarization proposed in literature have a monotonic one-to-one correspondence, thus providing the same information about the field's polarization state.
Abstract: We show that, for 3D random electromagnetic fields that are created by optical systems from a partially polarized plane wave, two different definitions of the 3D degree of polarization proposed in literature have a monotonic one-to-one correspondence, thus providing the same information about the field's polarization state. Examples of 3D fields obeying this result are the evanescent wave generated in total internal reflection, the tightly focused beam, and the far field scattered from an electric point dipole.
TL;DR: The results suggest that the polarization vortex evaluates the global polarization property of the closed-loop electron that plays an important role in the quantum correlation phenomena such as the Aharonov-Bohm effect.
Abstract: We evaluate the quasi-one-dimensional (1D) electron dynamics in a NbSe3 ring crystal using polarization vortex pulses with various azimuthal distributions. The single particle relaxation component reveals a large anisotropy on the crystal, indicating that the electrons in the ring maintain their 1D character. The results also suggest that the polarization vortex evaluates the global polarization property of the closed-loop electron that plays an important role in the quantum correlation phenomena such as the Aharonov-Bohm effect.
TL;DR: The time-domain degree of polarization of a stationary, random optical beam, in general, differs from that in the frequency domain and the origin of their differences is elucidated.
Abstract: The time-domain degree of polarization of a stationary, random optical beam, in general, differs from that in the frequency domain. We elucidate the origin of their differences and consider several examples in which the two degrees of polarization either are or are not the same.
TL;DR: In this paper, the authors derived a statistical quantity that describes the rate at which the field intensity in the beam, on average, is redistributed between the beam's polarization state at any time and the state orthogonal to it.
Abstract: Two stationary, partially polarized electromagnetic beams with equal degrees of polarization may exhibit completely different time evolutions of the instantaneous polarization state. In this work, we derive a statistical quantity that describes the rate at which the field intensity in the beam, on average, is redistributed between the beam's polarization state at any time and the state orthogonal to it. This method allows one to treat the dynamical properties of the polarization fluctuations both theoretically and experimentally. We demonstrate the method by applying it to important special cases, such as fields obeying Gaussian statistics, black-body radiation pencils and depolarized laser beams. We also prove that a geometric approach introduced earlier is closely connected with the present model.
TL;DR: Based on the unified theory of coherence and polarization, the sufficient condition for Gaussian Schell-model (GSM) beam to keep the SOP unchanged is derived, and it is found that when the three spectral correlation widths are equal to each other and sigma(x) = s Sigma(y), the GSM beam maintains the Sop on propagation.
Abstract: In the free space optical communication system with circle polarization shift keying (CPolSK) modulation, the changes of polarization state of light beam have significant influence on the system performance. Keeping the state of polarization (SOP) unchanged on propagation can reduce the bit error rate. Based on the unified theory of coherence and polarization, we derive the sufficient condition for Gaussian Schell-model (GSM) beam to keep the SOP unchanged. We found that when the three spectral correlation widths (δxx, δyy and δxy) equal to each other and σx=σy, the GSM beam maintains the SOP on propagation. This conclusion can be helpful for the design of the transmitter in the CPolSK system.
TL;DR: The results to the oblique incidence case are extended and experimentally the optimal parameters for generation of a single charge on-axis optical vortex are confirmed, including spectrally resolved measurements for the white-light beams.
Abstract: We report on the experimental and theoretical investigation of polarization conversion of linearly polarized Gaussian beam propagating in perpendicularly cut homogeneous uniaxial crystals. We derive analytical expressions, in good agreement with experimental data, for power transfer between components at normal incidence accompanied by the generation of a topological quadrupole. We extend the results to the oblique incidence case and confirm experimentally the optimal parameters for generation of a single charge on-axis optical vortex, including spectrally resolved measurements for the white-light beams.
08 Oct 2009
TL;DR: In this article, the formation of local and statistical polarization structures of laser radiation scattered in phase-inhomogeneous layers of biological tissue was studied, and the distribution of azimuth and eccentricity of boundary field polarization was found to correlate with the orientation-phase structure of phase in homogeneous layers.
Abstract: Specific features of the formation of local and statistical polarization structures of laser radiation scattered in phaseinhomogeneous
layers of biological tissue were studied. The distribution of azimuth and eccentricity of boundary field
polarization was found to correlate with the orientation-phase structure of phase-inhomogeneous layers. A method of
polarization phase reconstruction of biological tissue architectonics was suggested.
TL;DR: The coupling efficiency of the x- and y-polarized fundamental modes between the horizontal and vertical rectangular waveguides is remarkably enhanced with the help of the TE(01) mode in the multimode waveguide.
Abstract: We propose and analyze a 90° polarization rotator based on wave coupling through an intermediate, multimode, axially uniform waveguide. The coupling efficiency of the x- and y-polarized fundamental modes between the horizontal and vertical rectangular waveguides is remarkably enhanced with the help of the TE01 mode in the multimode waveguide. The polarization rotator has a very short (21-μm) conversion length with a 17.22 dB extinction ratio. It also exhibits a 68-nm bandwidth for polarization conversion efficiency above 90%.
TL;DR: Influences of variable-angle polarization-rotated optical feedback on polarization properties of vertical-cavity surface-emitting lasers (VCSELs) are investigated numerically and the complementary properties of intensities between the two polarization modes for both cases are evaluated quantitatively in terms of the defined normalized intensity.
Abstract: Influences of variable-angle polarization-rotated optical feedback on polarization properties of vertical-cavity surface-emitting lasers (VCSELs) are investigated numerically For the so-called case A (x polarization) feedback, only the x mode is selected to pass through the feedback loop As the polarization angle is varied from 0 degrees to 90 degrees, the dominant polarization mode switching can be observed even for fixed feedback strength and bias current For the so-called case B (xy polarization) feedback, the total outputs of the VCSEL pass through the feedback loop The polarization property is much different from case A The dominant polarization mode switching occurs not in the entire range of polarization angles, however, but in the so-called critical angle, from where the intensities of both polarization modes become comparable to each other and keep around constant values, and can be observed In addition, the complementary properties of intensities between the two polarization modes for both cases are evaluated quantitatively in terms of the defined normalized intensity
TL;DR: An in-vacuum double-phase-plate diffractometer for performing polarization scans combined with resonant X-ray diffraction experiments is presented and measurements by means of polarization scans at the uranium M(4) edge on UO(2) enable the contributions of the magnetic and quadrupole ordering in the material to be disentangled.
Abstract: An in-vacuum double-phase-plate diffractometer for performing polarization scans combined with resonant X-ray diffraction experiments is presented. The use of two phase plates enables the correction of some of the aberration effects owing to the divergence of the beam and its energy spread. A higher rate of rotated polarization is thus obtained in comparison with a system with only a single retarder. Consequently, thinner phase plates can be used to obtain the required rotated polarization rate. These results are particularly interesting for applications at low energy (e.g. 4 keV) where the absorption owing to the phase plate(s) plays a key role in the feasibility of these experiments. Measurements by means of polarization scans at the uranium M(4) edge on UO(2) enable the contributions of the magnetic and quadrupole ordering in the material to be disentangled.
TL;DR: In this paper, the spin-dependent repulsive interaction between exciton polaritons with parallel spins has been investigated for GaAs microcavity operating in the strong coupling regime.
Abstract: We report on a pronounced nonlinear optical effect in a GaAs microcavity operating in the strong-coupling regime: cavity transmission in circular polarization is found to be much stronger than in linear polarization. This behavior has its origin in the spin-dependent repulsive interaction between exciton polaritons. Quantitative analysis allows estimating the strength of interaction between polaritons with parallel spins. The observed effect shows the potentiality of microcavities for circular polarization sensing essential for transmission of polarization encoded signals.
TL;DR: Due to a saturation effect, it is found that the output polarization lies on a ring when the polarization is represented onto the Poincaré sphere.
Abstract: We study the influence of Stimulated Brillouin Scattering on the polarization stabilization of a light beam propagating in a highly-birefringent optical fiber. In particular, due to a saturation effect, we find that the output polarization lies on a ring when the polarization is represented onto the Poincare sphere.