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Sample records for degree polarization rotator

  1. Detection of degree-scale B-mode polarization and studying cosmic polarization rotation with the BICEP1 and BICEP2 telescopes

    NASA Astrophysics Data System (ADS)

    Kaufman, Jonathan Philip

    The BICEP1 and BICEP2 telescopes studied the temperature and polarization of the Cosmic Microwave Background (CMB) from 2006 -- 2008 and 2010 -- 2012, respectively, producing the deepest maps of polarization created to date. From BICEP2 three-year data, we detect B-mode polarization at the degree-scale above the expectation from lensed-ΛCDM to greater than 5sigma significance, consistent with that expected from gravitational waves created during Inflation. Instrumental systematic effects have been characterized and ruled out, and galactic foreground contamination is disfavored by the data. Additionally, correlations between temperature and B-mode polarization and between E-mode and B-mode polarization show evidence of polarization rotation of --1° to 5sigma significance; however, adding systematic uncertainty reduces this significance to ˜ 2sigma. These measurements, combined with other CMB and astrophysical measurements, point to possible parity violating physics like cosmic birefringence, but more precise calibration techniques are required to break the degeneracy between cosmic polarization rotation and systematic effects. Improved calibration is possible with current generation technology and may be achieved within the next few years. In this work, I present experimental and analysis techniques employed for BICEP1 and BICEP2 to measure B-mode polarization and temperature and polarization correlations, as well as the scientific motivation, results, and a path forward for future measurements.

  2. A Translational Polarization Rotator

    NASA Technical Reports Server (NTRS)

    Chuss, David T.; Wollack, Edward J.; Pisano, Giampaolo; Ackiss, Sheridan; U-Yen, Kongpop; Ng, Ming wah

    2012-01-01

    We explore a free-space polarization modulator in which a variable phase introduction between right- and left-handed circular polarization components is used to rotate the linear polarization of the outgoing beam relative to that of the incoming beam. In this device, the polarization states are separated by a circular polarizer that consists of a quarter-wave plate in combination with a wire grid. A movable mirror is positioned behind and parallel to the circular polarizer. As the polarizer-mirror distance is separated, an incident liear polarization will be rotated through an angle that is proportional to the introduced phase delay. We demonstrate a prototype device that modulates Stokes Q and U over a 20% bandwidth.

  3. Polarizance of a synthetic mica crystal polarizer and the degree of linear polarization of an undulator beamline at 880 eV evaluated by the rotating-analyzer method

    SciTech Connect

    Imazono, Takashi; Hirono, Toko; Kimura, Hiroaki; Saitoh, Yuji; Ishino, Masahiko; Muramatsu, Yasuji; Koike, Masato; Sano, Kazuo

    2005-12-15

    The polarization performance of a reflection-type polarizer made with a synthetic mica (fluorophlogopite) single crystal (002) in symmetric Bragg geometry was evaluated at the photon energy of 880 eV by means of the rotating-analyzer method. An experiment was performed at the undulator beamline at the SPring-8. The reflectance in the s-polarization configuration was 2.6% at an incidence angle of around 45 deg. As the result of the analysis based on the rotating-analyzer method, the polarizance of the polarizer and the degree of linear polarization of the incident light at 880 eV were found to be 0.997{+-}0.002 and 0.993{+-}0.004, respectively.

  4. Linear polarization of rapidly rotating ultracool dwarfs

    NASA Astrophysics Data System (ADS)

    Miles-Páez, P. A.; Zapatero Osorio, M. R.; Pallé, E.; Peña Ramírez, K.

    2013-08-01

    Aims: We aim to study the near-infrared linear polarization signal of rapidly rotating ultracool dwarfs with spectral types ranging from M7 through T2 and projected rotational velocities of v sin i ≳ 30 km s-1. These dwarfs are believed to have dusty atmospheres and oblate shapes, which is an appropriate scenario to produce measurable linear polarization of the continuum light. Methods: Linear polarimetric images were collected in the J-band for a sample of 18 fast-rotating ultracool dwarfs, of which five were also observed in the Z-band using the Long-slit Intermediate Resolution Infrared Spectrograph (LIRIS) on the Cassegrain focus of the 4.2-m William Herschel Telescope. The measured median uncertainty in the linear polarization degree is ±0.13% for our sample, which allowed us to detect polarization signatures above ~0.39% with a confidence interval of ≥3σ. Results: About 40 ± 15% of the sample is linearly polarized in the Z- and J-bands. All positive detections have linear polarization degrees ranging from 0.4% to 0.8% in both filters independent of spectral type and spectroscopic rotational velocity. However, simple statistics point at the fastest rotators (v sin i ≳ 60 km s-1) having a larger fraction of positive detections and a larger averaged linear polarization degree than the moderately rotating dwarfs (v sin i = 30-60 km s-1). Our data suggest little linear polarimetric variability on short timescales (i.e., observations separated by a few ten rotation periods), and significant variability on long timescales (i.e., hundred to thousand rotation cycles), supporting the presence of long-term weather in ultracool dwarf atmospheres.

  5. Detection of endometrial lesions by degree of linear polarization maps

    NASA Astrophysics Data System (ADS)

    Kim, Jihoon; Fazleabas, Asgerally; Walsh, Joseph T.

    2010-02-01

    Endometriosis is one of the most common causes of chronic pelvic pain and infertility and is characterized by the presence of endometrial glands and stroma outside of the uterine cavity. A novel laparoscopic polarization imaging system was designed to detect endometriosis by imaging endometrial lesions. Linearly polarized light with varying incident polarization angles illuminated endometrial lesions. Degree of linear polarization image maps of endometrial lesions were constructed by using remitted polarized light. The image maps were compared with regular laparoscopy image. The degree of linear polarization map contributed to the detection of endometriosis by revealing structures inside the lesion. The utilization of rotating incident polarization angle (IPA) for the linearly polarized light provides extended understanding of endometrial lesions. The developed polarization system with varying IPA and the collected image maps could provide improved characterization of endometrial lesions via higher visibility of the structure of the lesions and thereby improve diagnosis of endometriosis.

  6. Cosmic polarization rotation: An astrophysical test of fundamental physics

    NASA Astrophysics Data System (ADS)

    di Serego Alighieri, Sperello

    2015-02-01

    Possible violations of fundamental physical principles, e.g. the Einstein equivalence principle on which all metric theories of gravity are based, including general relativity (GR), would lead to a rotation of the plane of polarization for linearly polarized radiation traveling over cosmological distances, the so-called cosmic polarization rotation (CPR). We review here the astrophysical tests which have been carried out so far to check if CPR exists. These are using the radio and ultraviolet polarization of radio galaxies and the polarization of the cosmic microwave background (both E-mode and B-mode). These tests so far have been negative, leading to upper limits of the order of one degree on any CPR angle, thereby increasing our confidence in those physical principles, including GR. We also discuss future prospects in detecting CPR or improving the constraints on it.

  7. Spectral degree of polarization uniformity for polarization-sensitive OCT

    PubMed Central

    Baumann, Bernhard; Zotter, Stefan; Pircher, Michael; Götzinger, Erich; Rauscher, Sabine; Glösmann, Martin; Lammer, Jan; Schmidt-Erfurth, Ursula; Gröger, Marion; Hitzenberger, Christoph K.

    2015-01-01

    Depolarization of light can be measured by polarization-sensitive optical coherence tomography (PS-OCT) and has been used to improve tissue discrimination as well as segmentation of pigmented structures. Most approaches to depolarization assessment for PS-OCT – such as the degree of polarization uniformity (DOPU) – rely on measuring the uniformity of polarization states using spatial evaluation kernels. In this article, we present a different approach which exploits the spectral dimension. We introduce the spectral DOPU for the pixelwise analysis of polarization state variations between sub-bands of the broadband light source spectrum. Alongside a comparison with conventional spatial and temporal DOPU algorithms, we demonstrate imaging in the healthy human retina, and apply the technique for contrasting hard exudates in diabetic retinopathy and investigating the pigment epithelium of the rat iris. PMID:26689829

  8. Spectral degree of polarization uniformity for polarization-sensitive OCT

    NASA Astrophysics Data System (ADS)

    Baumann, Bernhard; Zotter, Stefan; Pircher, Michael; Götzinger, Erich; Rauscher, Sabine; Glösmann, Martin; Lammer, Jan; Schmidt-Erfurth, Ursula; Gröger, Marion; Hitzenberger, Christoph K.

    2015-12-01

    Depolarization of light can be measured by polarization-sensitive optical coherence tomography (PS-OCT) and has been used to improve tissue discrimination as well as segmentation of pigmented structures. Most approaches to depolarization assessment for PS-OCT - such as the degree of polarization uniformity (DOPU) - rely on measuring the uniformity of polarization states using spatial evaluation kernels. In this article, we present a different approach which exploits the spectral dimension. We introduce the spectral DOPU for the pixelwise analysis of polarization state variations between sub-bands of the broadband light source spectrum. Alongside a comparison with conventional spatial and temporal DOPU algorithms, we demonstrate imaging in the healthy human retina, and apply the technique for contrasting hard exudates in diabetic retinopathy and investigating the pigment epithelium of the rat iris.

  9. Electrically rotating suspended films of polar liquids

    NASA Astrophysics Data System (ADS)

    Shirsavar, R.; Amjadi, A.; Tonddast-Navaei, A.; Ejtehadi, M. R.

    2011-02-01

    Controlled rotation of a suspended soap water film, simply generated by applying an electric field, has been reported recently. The film rotates when the applied electric field exceeds a certain threshold. In this study, we investigate the phenomenon in films made of a number of other liquids with various physical and chemical properties. Our measurements show that the intrinsic electrical dipole moments of the liquid molecules seems to be vital for the corresponding film rotation. All the investigated rotating liquids have a molecular electric dipole moment of above 1 Debye, while weakly polar liquids do not rotate. However, the liquids investigated here cover a wide range of physical parameters (e.g. viscosity, density, conductivity, etc.). So far, no significant correlation has been observed between the electric field thresholds and macroscopic properties of the liquids.

  10. Toroidal rotation driven by the polarization drift.

    PubMed

    McDevitt, C J; Diamond, P H; Gürcan, O D; Hahm, T S

    2009-11-13

    Starting from a phase space conserving gyrokinetic formulation, a systematic derivation of parallel momentum conservation uncovers a novel mechanism by which microturbulence may drive intrinsic rotation. This mechanism, which appears in the gyrokinetic formulation through the parallel nonlinearity, emerges due to charge separation induced by the polarization drift. The derivation and physical discussion of this mechanism will be pursued throughout this Letter. PMID:20365987

  11. Renormalized vacuum polarization of rotating black holes

    NASA Astrophysics Data System (ADS)

    Ferreira, Hugo R. C.

    2015-04-01

    Quantum field theory on rotating black hole spacetimes is plagued with technical difficulties. Here, we describe a general method to renormalize and compute the vacuum polarization of a quantum field in the Hartle-Hawking state on rotating black holes. We exemplify the technique with a massive scalar field on the warped AdS3 black hole solution to topologically massive gravity, a deformation of (2 + 1)-dimensional Einstein gravity. We use a "quasi-Euclidean" technique, which generalizes the Euclidean techniques used for static spacetimes, and we subtract the divergences by matching to a sum over mode solutions on Minkowski spacetime. This allows us, for the first time, to have a general method to compute the renormalized vacuum polarization, for a given quantum state, on a rotating black hole, such as the physically relevant case of the Kerr black hole in four dimensions.

  12. Polarization Properties of Rotation Powered Pulsars

    NASA Technical Reports Server (NTRS)

    Harding Alice K.

    2009-01-01

    Polarization measurements of rotation-powered pulsars and their nebulae have unique diagnostic potential. The polarization position angle of the pulsar wind nebula, as is know for the Crab pulsar, can tell us the orientation of the spin axis. Phase-resolved polarimetry of pulsars has had enormous diagnostic capability at radio and optical wavelengths and could also be a powerful diagnostic in the X-ray range. Measurement of the polarization properties as a function of pulse phase can therefore provide a multidimensional mapping of the pulsar emission. In the 'rotating vector' model, radiation originating near a magnetic pole is expected to show a characteristic S-shaped swing of the position angle vs. pulse phase. In this case it is possible to determine the magnetic inclination and viewing angles. Radiation originating further from the poles or further above the neutron star surface will have a more complex polarization signature, as a result of relativistic effects of aberration and time-of-flight delays and may also cause depolarization of the signal. I will discuss predicted polarization properties of pulsed emission in polar cap models, where radiation originates near the neutron star surface at the magnetic poles, and in slot gap and outer gap models, where radiation originates over a range of altitudes out to the speed-of-light cylinder.

  13. Optical polarization plane rotation for the blazar PG 1553+113

    NASA Astrophysics Data System (ADS)

    Blinov, D.; Casadi, C.

    2016-09-01

    We report about RoboPol observations of the ongoing rotation of the optical polarization angle for the blazar PG 1553+113 (RA=15h55m43s; Dec=+11d11m24s). The rotation began around August, 19. So far the total amplitude of the rotation is ~130 degrees with an average rate of ~8 deg/day.

  14. Developments in Coherent Perfect Polarization Rotation

    NASA Astrophysics Data System (ADS)

    Crescimanno, Michael; Andrews, James; Zhou, Chaunhong; Baker, Michael

    2015-05-01

    Coherent Perfect Polarization Rotation (CPR) is a useful technique akin to Coherent Perfect Absorption (CPA, also known as the anti-laser) but that results in very high efficiency optical mode conversion. We describe the analysis of recent experimental data from our CPR testbed, the use of CPR in miniaturizing optical isolators and CPR phenomena in non-linear optics. Work supported by the N.S.F. under Grant No. ECCS-1360725.

  15. Evolution of the polarization of the He-Ne-laser radiation in a rotating insulator

    NASA Astrophysics Data System (ADS)

    Gladyshev, V. O.; Portnov, D. I.

    2015-04-01

    The propagation of the polarized coherent radiation of a He-Ne laser in a rotating insulator is experimentally studied. The reversible transient process of the rotation of the polarization plane and variations in the degree of ellipticity, depolarization, and deflection of the laser beam with a relaxation time of τ = 102-103 s are observed at an insulator rotation frequency of f = 2-250 Hz.

  16. Macroscopic rotation of photon polarization induced by a single spin

    PubMed Central

    Arnold, Christophe; Demory, Justin; Loo, Vivien; Lemaître, Aristide; Sagnes, Isabelle; Glazov, Mikhaïl; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loïc

    2015-01-01

    Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10−3 degrees due to poor spin–photon coupling. Here we report the enhancement by three orders of magnitude of the spin–photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ±6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network. PMID:25687134

  17. Macroscopic rotation of photon polarization induced by a single spin.

    PubMed

    Arnold, Christophe; Demory, Justin; Loo, Vivien; Lemaître, Aristide; Sagnes, Isabelle; Glazov, Mikhaïl; Krebs, Olivier; Voisin, Paul; Senellart, Pascale; Lanco, Loïc

    2015-01-01

    Entangling a single spin to the polarization of a single incoming photon, generated by an external source, would open new paradigms in quantum optics such as delayed-photon entanglement, deterministic logic gates or fault-tolerant quantum computing. These perspectives rely on the possibility that a single spin induces a macroscopic rotation of a photon polarization. Such polarization rotations induced by single spins were recently observed, yet limited to a few 10(-3) degrees due to poor spin-photon coupling. Here we report the enhancement by three orders of magnitude of the spin-photon interaction, using a cavity quantum electrodynamics device. A single hole spin in a semiconductor quantum dot is deterministically coupled to a micropillar cavity. The cavity-enhanced coupling between the incoming photons and the solid-state spin results in a polarization rotation by ± 6° when the spin is optically initialized in the up or down state. These results open the way towards a spin-based quantum network. PMID:25687134

  18. Degree of Polarization at Simultaneous Transmit: Theoretical Aspects

    SciTech Connect

    Galletti M.; Zrnic, D. S.

    2012-05-01

    We consider weather radar measurements at simultaneous transmission and simultaneous reception of horizontal and vertical polarizations and show that the degree of polarization at simultaneous transmit (p{sub s}) is related to differential reflectivity and copolar correlation coefficient at simultaneous transmit (namely, Z{sub DR}s and {rho}{sub hy}s). We evaluate the potential of degree of polarization at simultaneous transmit for weather radar applications. Ultimately, we explore the consequences of adjusting the transmit polarization state of dual-polarization weather radars to circular polarization.

  19. Ultra-thin, single-layer polarization rotator

    NASA Astrophysics Data System (ADS)

    Son, T. V.; Truong, V. V.; Do, P. A.; Haché, A.

    2016-08-01

    We demonstrate light polarization control over a broad spectral range by a uniform layer of vanadium dioxide as it undergoes a phase transition from insulator to metal. Changes in refractive indices create unequal phase shifts on s- and p-polarization components of incident light, and rotation of linear polarization shows intensity modulation by a factor of 103 when transmitted through polarizers. This makes possible polarization rotation devices as thin as 50 nm that would be activated thermally, optically or electrically.

  20. Polarization-Rotating Sensors Connected To Optical Fibers

    NASA Technical Reports Server (NTRS)

    Frazer, Robert E.

    1992-01-01

    Proposed optoelectronic sensor system includes polarization-rotating sensing elements interrogated by polarized light transmitted to and from sensing elements along optical fibers. Polarization of light altered by combinations of inherent birefringence, stress-induced birefrigence, and Faraday rotation. Advantages include: light weight, fast response, immunity to electromagnetic interference at radio and lower frequencies, and no need to supply electrical power to sensing elements.

  1. Freely tunable broadband polarization rotator for terahertz waves.

    PubMed

    Fan, Ren-Hao; Zhou, Yu; Ren, Xiao-Ping; Peng, Ru-Wen; Jiang, Shang-Chi; Xu, Di-Hu; Xiong, Xiang; Huang, Xian-Rong; Wang, Mu

    2015-02-18

    A freely tunable polarization rotator for broadband terahertz waves is demonstrated using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized terahertz wave to any desired direction with nearly perfect conversion efficiency. This low-cost, high-efficiency, and freely tunable device has potential applications as material analysis, wireless communication, and THz imaging. PMID:25545177

  2. Polarization rotator-splitters in standard active silicon photonics platforms.

    PubMed

    Sacher, Wesley D; Barwicz, Tymon; Taylor, Benjamin J F; Poon, Joyce K S

    2014-02-24

    We demonstrate various silicon-on-insulator polarization management structures based on a polarization rotator-splitter that uses a bi-level taper TM0-TE1 mode converter. The designs are fully compatible with standard active silicon photonics platforms with no new levels required and were implemented in the IME baseline and IME-OpSIS silicon photonics processes. We demonstrate a polarization rotator-splitter with polarization crosstalk < -13 dB over a bandwidth of 50 nm. Then, we improve the crosstalk to < -22 dB over a bandwidth of 80 nm by integrating the polarization rotator-splitter with directional coupler polarization filters. Finally, we demonstrate a polarization controller by integrating the polarization rotator-splitters with directional couplers, thermal tuners, and PIN diode phase shifters. PMID:24663698

  3. Dynamic rotation and stretch tensors from a dynamic polar decomposition

    NASA Astrophysics Data System (ADS)

    Haller, George

    2016-01-01

    The local rigid-body component of continuum deformation is typically characterized by the rotation tensor, obtained from the polar decomposition of the deformation gradient. Beyond its well-known merits, the polar rotation tensor also has a lesser known dynamical inconsistency: it does not satisfy the fundamental superposition principle of rigid-body rotations over adjacent time intervals. As a consequence, the polar rotation diverts from the observed mean material rotation of fibers in fluids, and introduces a purely kinematic memory effect into computed material rotation. Here we derive a generalized polar decomposition for linear processes that yields a unique, dynamically consistent rotation component, the dynamic rotation tensor, for the deformation gradient. The left dynamic stretch tensor is objective, and shares the principal strain values and axes with its classic polar counterpart. Unlike its classic polar counterpart, however, the dynamic stretch tensor evolves in time without spin. The dynamic rotation tensor further decomposes into a spatially constant mean rotation tensor and a dynamically consistent relative rotation tensor that is objective for planar deformations. We also obtain simple expressions for dynamic analogues of Cauchy's mean rotation angle that characterize a deforming body objectively.

  4. Polarization Rotation by Multilayered Chiral Metamaterial

    NASA Astrophysics Data System (ADS)

    Zhang, Yumin; Nathan Burford Collaboration

    2013-03-01

    Traditionally, negative permittivity was realized by plasma resonance of the metallic structures, and negative permeability was achieved by a resonant LC circuit. Chiral metamaterial is another route to achieve negative permittivity and permeability, and such structures were investigated at different frequency domains. Recently, it was demonstrated that a two-dimensional lattice of three-dimensional gold spirals can effectively block circular polarized light with the same handedness for a frequency range exceeding one octave. From the point of view of applications, metamaterials must be fabricated easily and cheaply, and one way to achieve this goal is planarization. We designed a multiple-layer quasi-helix PCB structure and had it fabricated. The sample was tested with automated free space microwave material measurement system at X-band. These layers of PCB can be arranged in two different configurations: left-handed or right- handed helix. We found that the polarization plane is rotated in the opposite direction for the left- and right-handed samples, and the measured S-parameters agree with the simulation result relatively well. The authors would like to acknowledge the support from GRFC grant from Southeast Missouri State University.

  5. Freely-tunable broadband polarization rotator for terahertz waves

    NASA Astrophysics Data System (ADS)

    Peng, Ru-Wen; Fan, Ren-Hao; Zhou, Yu; Jiang, Shang-Chi; Xiong, Xiang; Huang, Xian-Rong; Wang, Mu

    It is known that commercially-available terahertz (THz) emitters usually generate linearly polarized waves only along certain directions, but in practice, a polarization rotator that is capable of rotating the polarization of THz waves to any direction is particularly desirable and it will have various important applications. In this work, we demonstrate a freely tunable polarization rotator for broadband THz waves using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized THz wave to any desired direction with nearly perfect conversion efficiency. The device performance has been experimentally demonstrated by both THz transmission spectra and direct imaging. The polarization rotation originates from multi wave interference in the three-layer grating structure based on the scattering-matrix analysis. We can expect that this active broadband polarization rotator has wide applications in analytical chemistry, biology, communication technology, imaging, etc.. Reference: R. H. Fan, Y. Zhou, X. P. Ren, R. W. Peng, S. C. Jiang, D. H. Xu, X. Xiong, X. R. Huang, and Mu Wang, Advanced Materials 27,1201(2015). Freely-tunable broadband polarization rotator for terahertz waves.

  6. Spirit 360-Degree View, Sol 388 (polar)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 388th martian day, or sol (Feb. 4, 2005). Spirit had driven about 13 meters (43 feet) uphill toward 'Cumberland Ridge' on this sol. This location is catalogued as Spirit's Site 102, Position 513. The view is presented in a cylindrical projection with geometric and brightness seam correction.

  7. Apodised aperture using rotation of plane of polarization

    DOEpatents

    Simmons, W.W.; Leppelmeier, G.W.; Johnson, B.C.

    1975-09-01

    An apodised aperture based on the rotation of plane of polarization producing desirable characteristics on a transmitted light beam such as beam profiling in high flux laser amplifier chains is described. The apodised aperture is made with a lossless element by using one or more polarizers and/or analyzers and magneto-optical Faraday means for selectively rotating the plane of polarized radiation over the cross section to effect the desired apodisation. (auth)

  8. Laser scanning by rotating polarization gratings.

    PubMed

    Zhou, Yuan; Fan, Dapeng; Fan, Shixun; Chen, Ying; Liu, Guangcan

    2016-07-01

    Laser beam scanning can be realized using two independently rotating, inline polarization gratings, termed Risley gratings, in a fashion similar to Risley prisms. The analytical formulas of pointing position as well as their inverse solutions are described. On this basis, the beam scanning is investigated and the performance of scanning imaging is evaluated. It is shown that the scanning function in 1D scanning evolves from a sinusoidal to triangular scan and the duty cycle increases rapidly as the ratio of grating period to wavelength is reduced toward 2. The scan pattern in 2D scanning is determined by the ratio k of the gratings' rotatory frequency. In imaging applications, when k tends toward 1 or -1, the scan pattern becomes dense and is inclined to be spiral or rose-like, respectively, which is desirable for the purpose of enhancing spatial resolution. There is a direct trade-off between spatial resolution and frame rate. The spiral and rose scanning enable multiresolution imaging, providing a preview of the scanned area in a fraction of the overall scan time, which is extremely useful for fast, real-time imaging applications. PMID:27409203

  9. Measurement of Small Optical Polarization Rotations

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2009-01-01

    When data with and without an optically active sample are acquired simultaneously while one manually rotates the analyser, the graph of the first signal versus the second one is an ellipse whose shape shows the phase shift between the two signals; this shift is twice the optical rotation. There is no need to measure the rotation of the analyser or…

  10. Polarization rotation under two-photon Raman resonance for magnetometry

    SciTech Connect

    Pradhan, S.; Behera, R.; Das, A. K.

    2012-04-23

    The polarization rotation and coherent population trapping signal arising due to two photon process using linearly polarized light are found to be significantly enhanced for a Zeeman degenerate system. The zero crossing of the dispersive profile is found to be shifting proportional to the applied magnetic field, albeit the absorptive profile position remains invariant for a slightly imbalanced orthogonal circular polarization component. It provides an alternative method for precise measurement of vector magnetic field without requirement of a bias field. The use of polarization rotation signal for magnetic field measurement offers added advantage due to improved signal to noise ratio.

  11. On the Rotation of Sunspots and Their Magnetic Polarity

    NASA Astrophysics Data System (ADS)

    Zheng, Jianchuan; Yang, Zhiliang; Guo, Kaiming; Wang, Haimin; Wang, Shuo

    2016-07-01

    The rotation of sunspots of 2 yr in two different solar cycles is studied with the data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observataory. We choose the α sunspot groups and the relatively large and stable sunspots of complex active regions in our sample. In the year of 2003, the α sunspot groups and the preceding sunspots tend to rotate counterclockwise and have positive magnetic polarity in the northern hemisphere. In the southern hemisphere, the magnetic polarity and rotational tendency of the α sunspot groups and the preceding sunspots are opposite to the northern hemisphere. The average rotational speed of these sunspots in 2003 is about 0.°65 hr‑1. From 2014 January to 2015 February, the α sunspot groups and the preceding sunspots tend to rotate clockwise and have negative magnetic polarity in the northern hemisphere. The patterns of rotation and magnetic polarity of the southern hemisphere are also opposite to those of the northern hemisphere. The average rotational speed of these sunspots in 2014/2015 is about 1.°49 hr‑1. The rotation of the relatively large and stable preceding sunspots and that of the α sunspot groups located in the same hemisphere have opposite rotational direction in 2003 and 2014/2015.

  12. Integrated polarization rotator/converter by stimulated Raman adiabatic passage.

    PubMed

    Xiong, Xiao; Zou, Chang-Ling; Ren, Xi-Feng; Guo, Guang-Can

    2013-07-15

    We proposed a polarization rotator inspired by stimulated Raman adiabatic passage model from quantum optics, which is composed of a signal waveguide and an ancillary waveguide. The two orthogonal modes in signal waveguide and the oblique mode in ancillary waveguide form a Λ-type three-level system. By controlling the width of signal waveguide and the gap between two waveguides, adiabatic conversion between two orthogonal modes can be realized in the signal waveguide. With such adiabatic passage, polarization conversion is completed within 150 μm length, with the efficiencies over 99% for both conversions between horizontal polarization and vertical polarization. In addition, such a polarization rotator is quite robust against fabrication error, allowing a wide range of tolerances for the rotator geometric parameters. Our work is not only significative to photonic simulations of coherent quantum phenomena with engineered photonic waveguides, but also enlightens the practical applications of these phenomena in optical device designs. PMID:23938558

  13. New Constraints on Cosmic Polarization Rotation from B-Mode Polarization in the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    di Serego Alighieri, Sperello; Ni, Wei-Tou; Pan, Wei-Ping

    2014-09-01

    SPTpol, POLARBEAR, and BICEP2 have recently measured the cosmic microwave background (CMB) B-mode polarization in various sky regions of several tens of square degrees and obtained BB power spectra in the multipole range 20-3000, detecting the components due to gravitational lensing and to inflationary gravitational waves. We analyze jointly the results of these three experiments and propose modifications to their analyses of the spectra to include in the model, in addition to the gravitational lensing and the inflationary gravitational wave components, and also the effects induced by the cosmic polarization rotation (CPR), if it exists within current upper limits. Although in principle our analysis would also lead to new constraints on CPR, in practice these can only be given on its fluctuations langδα2rang, since constraints on its mean angle are inhibited by the derotation which is applied by current CMB polarization experiments, in order to cope with the insufficient calibration of the polarization angle. The combined data fits from all three experiments (with 29% CPR-SPTpol correlation, depending on the theoretical model) gives the constraint langδα2rang1/2 < 27.3 mrad (1.°56), with r = 0.194 ± 0.033. These results show that the present data are consistent with no CPR detection and the constraint on CPR fluctuation is about 1.°5. This method of constraining the CPR is new, is complementary to previous tests, which use the radio and optical/UV polarization of radio galaxies and the CMB E-mode polarization, and adds a new constraint for the sky areas observed by SPTpol, POLARBEAR, and BICEP2.

  14. New constraints on cosmic polarization rotation from B-mode polarization in the cosmic microwave background

    SciTech Connect

    Alighieri, Sperello di Serego; Ni, Wei-Tou; Pan, Wei-Ping E-mail: weitou@gmail.com

    2014-09-01

    SPTpol, POLARBEAR, and BICEP2 have recently measured the cosmic microwave background (CMB) B-mode polarization in various sky regions of several tens of square degrees and obtained BB power spectra in the multipole range 20-3000, detecting the components due to gravitational lensing and to inflationary gravitational waves. We analyze jointly the results of these three experiments and propose modifications to their analyses of the spectra to include in the model, in addition to the gravitational lensing and the inflationary gravitational wave components, and also the effects induced by the cosmic polarization rotation (CPR), if it exists within current upper limits. Although in principle our analysis would also lead to new constraints on CPR, in practice these can only be given on its fluctuations (δα{sup 2}), since constraints on its mean angle are inhibited by the derotation which is applied by current CMB polarization experiments, in order to cope with the insufficient calibration of the polarization angle. The combined data fits from all three experiments (with 29% CPR-SPTpol correlation, depending on the theoretical model) gives the constraint (δα{sup 2}){sup 1/2} < 27.3 mrad (1.°56), with r = 0.194 ± 0.033. These results show that the present data are consistent with no CPR detection and the constraint on CPR fluctuation is about 1.°5. This method of constraining the CPR is new, is complementary to previous tests, which use the radio and optical/UV polarization of radio galaxies and the CMB E-mode polarization, and adds a new constraint for the sky areas observed by SPTpol, POLARBEAR, and BICEP2.

  15. Traceability study of optical fiber degree of polarization (DOP) measurement

    NASA Astrophysics Data System (ADS)

    Xu, Nan; Li, Jianwei; Li, Jian; Zhang, Zhixin

    2013-09-01

    Degree of polarization (DOP) is an important physical quantity for describing the optical polarization effect and is widely applied in optical fiber communication, optical fiber gyro and the related technologies. Currently, the optical polarization degree tester for the purpose of communication uses mainly two kinds of measurement methods: Stokes vector method and extremum method. At present, there isn't a standard to measure the accuracy and consistency of DOP parameter measurement by the devices listed above, affecting seriously the application of DOP parameter measurement in the fields of optical fiber gyro and optical fiber communication. So, it is urgent to table the accurate guarantees to trace the source of quantitative values of the DOP measuring devices and testers. In this paper, the polarization beam combination method is raised to research and manufacture the standard optical fiber light source device with the variable DOP, and an indicated error measurement has been conducted for a DOP meter. A kind of standard optical fiber light source device that uses a single light source to realize the variable DOP is put forward. It is used to provide the accurate and variable optical fiber polarization degree light with a scope of 0~100%. It is used to calibrate the DOP meters and widely applied in the field of national defense and optical communication fields. By using the standard optical power meter, DOP value by which the optical power meter calculates the optical signal can be measured, which will be used ultimately for calibration of the DOP meter. A measurement uncertainty of 0.5% is obtained using the polarization beam combination method.

  16. Primordial gravitational waves measurements and anisotropies of CMB polarization rotation

    NASA Astrophysics Data System (ADS)

    Li, Si-Yu; Xia, Jun-Qing; Li, Mingzhe; Li, Hong; Zhang, Xinmin

    2015-12-01

    Searching for the signal of primordial gravitational waves in the B-modes (BB) power spectrum is one of the key scientific aims of the cosmic microwave background (CMB) polarization experiments. However, this could be easily contaminated by several foreground issues, such as the interstellar dust grains and the galactic cyclotron electrons. In this paper we study another mechanism, the cosmic birefringence, which can be introduced by a CPT-violating interaction between CMB photons and an external scalar field. Such kind of interaction could give rise to the rotation of the linear polarization state of CMB photons, and consequently induce the CMB BB power spectrum, which could mimic the signal of primordial gravitational waves at large scales. With the recently released polarization data of BICEP2 and the joint analysis data of BICEP2/Keck Array and Planck, we perform a global fitting analysis on constraining the tensor-to-scalar ratio r by considering the polarization rotation angle [ α (n ˆ)] which can be separated into a background isotropic part [ α bar ] and a small anisotropic part [ Δα (n ˆ)]. Since the data of BICEP2 and Keck Array experiments have already been corrected by using the "self-calibration" method, here we mainly focus on the effects from the anisotropies of CMB polarization rotation angle. We find that including Δα (n ˆ) in the analysis could slightly weaken the constraints on the tensor-to-scalar ratio r, when using current CMB polarization measurements. We also simulate the mock CMB data with the BICEP3-like sensitivity. Very interestingly, we find that if the effects of the anisotropic polarization rotation angle could not be taken into account properly in the analysis, the constraints on r will be dramatically biased. This implies that we need to break the degeneracy between the anisotropies of the CMB polarization rotation angle and the CMB primordial tensor perturbations, in order to measure the signal of primordial gravitational

  17. Magnetic-Field-Induced Rotation of Polarized Light Emission from Monolayer WS2

    NASA Astrophysics Data System (ADS)

    Schmidt, Robert; Arora, Ashish; Plechinger, Gerd; Nagler, Philipp; Granados del Águila, Andrés; Ballottin, Mariana V.; Christianen, Peter C. M.; Michaelis de Vasconcellos, Steffen; Schüller, Christian; Korn, Tobias; Bratschitsch, Rudolf

    2016-08-01

    We control the linear polarization of emission from the coherently emitting K+ and K- valleys (valley coherence) in monolayer WS2 with an out-of-plane magnetic field of up to 25 T. The magnetic-field-induced valley Zeeman splitting causes a rotation of the emission polarization with respect to the excitation by up to 35° and reduces the polarization degree by up to 16%. We explain both of these phenomena with a model based on two noninteracting coherent two-level systems. We deduce that the coherent light emission from the valleys decays with a time constant of τc=260 fs .

  18. Changes in the earth's rotation and low-degree gravitational field induced by earthquakes

    NASA Technical Reports Server (NTRS)

    Chao, B. Fong; Gross, Richard S.

    1987-01-01

    Analytical formulas based on the normal-mode theory are used together with a spherically symmetric earth model and the centroid-moment tensor solutions for earthquake sources to compute the earthquake-induced changes in the earth's rotation and low-degree harmonics of the gravitational field for the period 1977-1985. Spectral and statistical analyses are conducted on these changes. It is found that the earthquake-induced changes are two orders of magnitude smaller than those observed; most of these changes show strong evidence of nonrandomness either in their polarity or in their directions.

  19. Polarization of Directly Imaged Young Giant Planets as a Probe of Mass, Rotation, and Clouds

    NASA Technical Reports Server (NTRS)

    Marley, Mark Scott; Sengupta, Sujan

    2012-01-01

    Young, hot gas giant planets at large separations from their primaries have been directly imaged around several nearby stars. More such planets will likely be detected by ongoing and new imaging surveys with instruments such as the Gemini Planet Imager (GPI). Efforts continue to model the spectra of these planets in order to constrain their masses, effective temperatures, composition, and cloud structure. One potential tool for analyzing these objects, which has received relatively less attention, is polarization. Linear polarization of gas giant exoplanets can arise from the combined influences of light scattering by atmospheric dust and a rotationally distorted shape. The oblateness of gas giant planet increases of course with rotation rate and for fixed rotation also rises with decreasing gravity. Thus young, lower mass gas giant planets with youthful inflated radii could easily have oblateness greater than that of Saturn s 10%. We find that polarizations of over 1% may easily be produced in the near-infrared in such cases. This magnitude of polarization may be measurable by GPI and other instruments. Thus if detected, polarization of a young Jupiter places constraints on the combination of its gravity, rotation rate, and degree of cloudiness. We will present results of our multiple scattering analysis coupled with a self-consistent dusty atmospheric models to demonstrate the range of polarizations that might be expected from resolved exoplanets and the range of parameter space that such observations may inform.

  20. Measurement of polarization with the Degree Angular Scale Interferometer.

    PubMed

    Leitch, E M; Kovac, J M; Pryke, C; Carlstrom, J E; Halverson, N W; Holzapfel, W L; Dragovan, M; Reddall, B; Sandberg, E S

    Measurements of the cosmic microwave background (CMB) radiation can reveal with remarkable precision the conditions of the Universe when it was approximately 400,000 years old. The three most fundamental properties of the CMB are its frequency spectrum (which determines the temperature), and the fluctuations in both the temperature and polarization across a range of angular scales. The frequency spectrum has been well determined, and considerable progress has been made in measuring the power spectrum of the temperature fluctuations. But despite many efforts to measure the polarization, detection of this property of the CMB has hitherto been beyond the reach of even the most sensitive observations. Here we describe the Degree Angular Scale Interferometer (DASI), an array of radio telescopes, which for the past two years has conducted polarization-sensitive observations of the CMB from the Amundsen-Scott South Pole research station. PMID:12490940

  1. Degree of polarization of light diffracted from resting striated muscle.

    PubMed

    Leung, A F

    1987-04-01

    A laser light diffractometer has been developed to measure directly the total degree of polarization of (alpha t) of light diffracted and randomly scattered from striated muscle fibers. From alpha t the degree of polarization (alpha d) of light diffracted from the periodically arranged contractile filaments is determined. Measurements on single muscle fibers and small fiber bundles indicate that both alpha t and alpha d of the first-order diffraction decrease monotonically with sarcomere length. For the second-order diffraction, alpha t and alpha d exhibit a peak at sarcomere length of about 3.0 micron. A proposed theory based on the anisotropic light scattering efficiencies of the thick and thin filaments can account for the measurements. The comparison between the theory and measurements indicates that the A-band, as well as the I-band, are optically anisotropic. PMID:2443248

  2. Ultracompact silicon-on-insulator polarization rotator for polarization-diversified circuits.

    PubMed

    Guan, Hang; Ma, Yangjin; Shi, Ruizhi; Novack, Ari; Tao, Jingcheng; Fang, Qing; Lim, Andy Eu-Jin; Lo, Guo-Qiang; Baehr-Jones, Tom; Hochberg, Michael

    2014-08-15

    We present an ultracompact (15.3 μm long) and high-efficiency silicon-on-insulator polarization rotator designed for polarization-diversified circuits. The rotator is comprised of a bilevel-tapered TM0-to-TE1 mode converter and a novel bent-tapered TE1-to-TE0 mode converter. The rotator has a simulated polarization conversion loss lower than 0.2 dB and a polarization-extinction ratio larger than 25 dB over a wavelength range of 80 nm around 1550 nm. The rotator has a SiO2 top-cladding and can be fabricated in a CMOS-compatible process. PMID:25121853

  3. Polarization Shaping for Unidirectional Rotational Motion of Molecules

    NASA Astrophysics Data System (ADS)

    Karras, G.; Ndong, M.; Hertz, E.; Sugny, D.; Billard, F.; Lavorel, B.; Faucher, O.

    2015-03-01

    Control of the orientation of the angular momentum of linear molecules is demonstrated by means of laser polarization shaping. For this purpose, we combine two orthogonally polarized and partially time-overlapped femtosecond laser pulses so as to produce a spinning linear polarization which in turn induces unidirectional rotation of N2 molecules. The evolution of the rotational response is probed by a third laser beam that can be either linearly or circularly polarized. The physical observable is the frequency shift imparted to the probe beam as a manifestation of the angular Doppler effect. Our experimental results are confirmed by theoretical computations, which allow one to gain a deep physical insight into the laser-molecule interaction.

  4. Polarization shaping for unidirectional rotational motion of molecules.

    PubMed

    Karras, G; Ndong, M; Hertz, E; Sugny, D; Billard, F; Lavorel, B; Faucher, O

    2015-03-13

    Control of the orientation of the angular momentum of linear molecules is demonstrated by means of laser polarization shaping. For this purpose, we combine two orthogonally polarized and partially time-overlapped femtosecond laser pulses so as to produce a spinning linear polarization which in turn induces unidirectional rotation of N2 molecules. The evolution of the rotational response is probed by a third laser beam that can be either linearly or circularly polarized. The physical observable is the frequency shift imparted to the probe beam as a manifestation of the angular Doppler effect. Our experimental results are confirmed by theoretical computations, which allow one to gain a deep physical insight into the laser-molecule interaction. PMID:25815926

  5. Ultrasmall polarization rotation measurements via weak value amplification

    NASA Astrophysics Data System (ADS)

    de Lima Bernardo, Bertúlio; Azevedo, Sérgio; Rosas, Alexandre

    2014-06-01

    We propose a framework to analyze weak measurements based on an angular version of the von Neumann measurement scheme, where the coupling between the system and the meter causes rotation of the measuring variable. We also discuss an experimental application of this theory in which measurements of weak optical activity and reflection-induced polarization rotation could be amplified in nearly two orders of magnitude. It can shed a new light on a great variety of physical chemistry, molecular biology and nanotechnology studies.

  6. Increase of spin dephasing times in a 2D electron system with degree of initial spin polarization

    NASA Astrophysics Data System (ADS)

    Stich, D.; Korn, T.; Schulz, R.; Schuh, D.; Wegscheider, W.; Schüller, C.

    2008-03-01

    We report on time-resolved Faraday/Kerr rotation measurements on a high-mobility 2D electron system. A variable initial spin polarization is created in the sample by a circularly polarized pump pulse, and the spin polarization is tracked by measuring the Faraday/Kerr rotation of a time-delayed probe pulse. By varying the pump intensity, the initial spin polarization is changed from the low-polarization limit to a polarization degree of several percent. The observed spin dephasing time increases from less than 20 ps to more than 200 ps as the initial spin polarization is increased. To exclude sample heating effects, additional measurements with constant pump intensity and variable degree of circular polarization are performed. The results confirm the theoretical prediction by Weng and Wu [Phys. Rev. B 68 (2003) 075312] that the spin dephasing strongly depends on the initial spin polarization degree. The microscopic origin for this is the Hartree-Fock term in the Coulomb interaction, which acts as an effective out-of plane magnetic field.

  7. Searching for Faraday rotation in cosmic microwave background polarization

    NASA Astrophysics Data System (ADS)

    Ruiz-Granados, B.; Battaner, E.; Florido, E.

    2016-08-01

    We use the Wilkinson Microwave Anisotropy Probe (WMAP) 9th-year foreground reduced data at 33, 41 and 61 GHz to derive a Faraday rotation at map and at angular power spectrum levels taking into account their observational errors. A processing mask provided by WMAP is used to avoid contamination from the disc of our Galaxy and local spurs. We have found a Faraday rotation component at both, map and power spectrum levels. The lack of correlation of the Faraday rotation with Galactic Faraday rotation, synchrotron and dust polarization from our Galaxy or with cosmic microwave background anisotropies or lensing suggests that it could be originated at reionization (ℓ ≲ 12). Even if the detected Faraday rotation signal is weak, the present study could contribute to establish magnetic fields strengths of B0 ˜ 10-8 G at reionization.

  8. Zeno inhibition of polarization rotation in an optically active medium

    NASA Astrophysics Data System (ADS)

    Gonzalo, Isabel; Porras, Miguel A.; Luis, Alfredo

    2015-07-01

    We describe an experiment in which the rotation of the polarization of light propagating in an optically active water solution of D-fructose tends to be inhibited by frequent monitoring whether the polarization remains unchanged. This is an example of the Zeno effect that has remarkable pedagogical interest because of its conceptual simplicity, easy implementation, low cost, and because the same the Zeno effect holds at classical and quantum levels. An added value is the demonstration of the Zeno effect beyond typical idealized assumptions in a practical setting with real polarizers.

  9. Comparison of 180-degree and 90-degree needle rotation to reduce wound size in PIT-injected juvenile Chinook salmon

    SciTech Connect

    Bryson, Amanda J.; Woodley, Christa M.; Karls, Rhonda K.; Hall, Kathleen D.; Weiland, Mark A.; Deng, Zhiqun; Carlson, Thomas J.; Eppard, Matthew B.

    2013-04-30

    Animal telemetry, which requires the implantation of passive transponders or active transmitters, is used to monitor and assess fish stock and conservation to gain an understanding of fish movement and behavior. As new telemetry technologies become available, studies of their effects on species of interest are imperative as is development of implantation techniques. In this study, we investigated the effects of bevel rotation (0-, 90-, 180-degree axis rotation) on wound extent, tag loss, and wound healing rates in juvenile Chinook salmon injected with an 8-gauge needle, which is required for implantation of the novel injectable Juvenile Salmon Acoustic Telemetry Systems (JSATS) acoustic transmitter or large passive integrated transponder (PIT) tags. Although the injection sites were not closed after injection (e.g., with sutures or glue), there were no mortalities, dropped tags, or indications of fungus, ulceration, and/or redness around the wound. On Day 0 and post-implantation Day 7, the 90-degree bevel rotation produced smaller wound extent than the 180-degree bevel rotation. No axis rotation (0-degrees) resulted in the PIT tag frequently misleading or falling out upon injection. The results of this study indicated the 90-degree bevel rotation was the more efficient technique, produced less wound extent. Given the wound extent compared to size of fish, we recommend researchers should consider a 90-degree rotation over the 180-degree rotation in telemetry studies. Highlights •Three degrees of needle rotation were examined for effects in Chinook salmon. •Mortality, tag loss, wound extent, healing, and infection indicators were measured. •There were no mortalities, tag loss, or indications of infection. •The 90-degree needle rotation through Day 7 produced the smallest wound extent.

  10. Nonlinear polarization rotation and orthogonal polarization generation experienced in a single-beam configuration

    NASA Astrophysics Data System (ADS)

    Minkovski, N.; Petrov, G. I.; Saltiel, S. M.; Albert, O.; Etchepare, J.

    2004-09-01

    Nonlinear polarization rotation and generation of a polarization component orthogonal to the input beam were observed along fourfold axes of YVO4 and BaF2 crystals. We demonstrate experimentally that in both crystals the angle of rotation is proportional, at low intensities, to the square of the product of the input intensity and the crystal length and is the result of simultaneous action of two third-order processes. This type of nonlinear polarization rotation is driven by the real part of the cubic susceptibility. The recorded energy exchange between the two orthogonal components can exceed 10%. It is to our knowledge the highest energy-conversion efficiency achieved in a single beam nonresonant χ(3) interaction. A simple theoretical model is elaborated to describe the dependence of nonlinear polarization rotation and orthogonal polarization generation on the intensity of the input beam at both low- and high-intensity levels. It reveals the potential contributions from the real and the imaginary parts of the susceptibility tensor. Moreover, this kind of measurement is designed to permit the determination of the magnitude and the sign of the anisotropy of the real part of third-order nonlinearity in crystals with cubic or tetragonal symmetry on the basis of polarization-rotation measurements. The χxxxx(3) component of the third-order susceptibility tensor and its anisotropy sign and amplitude value for BaF2 and YVO4 crystals are estimated and discussed.

  11. Process and apparatus for measuring degree of polarization and angle of major axis of polarized beam of light

    DOEpatents

    Decker, Derek E.; Toeppen, John S.

    1994-01-01

    Apparatus and process are disclosed for calibrating measurements of the phase of the polarization of a polarized beam and the angle of the polarized optical beam's major axis of polarization at a diagnostic point with measurements of the same parameters at a point of interest along the polarized beam path prior to the diagnostic point. The process is carried out by measuring the phase angle of the polarization of the beam and angle of the major axis at the point of interest, using a rotatable polarizer and a detector, and then measuring these parameters again at a diagnostic point where a compensation apparatus, including a partial polarizer, which may comprise a stack of glass plates, is disposed normal to the beam path between a rotatable polarizer and a detector. The partial polarizer is then rotated both normal to the beam path and around the axis of the beam path until the detected phase of the beam polarization equals the phase measured at the point of interest. The rotatable polarizer at the diagnostic point may then be rotated manually to determine the angle of the major axis of the beam and this is compared with the measured angle of the major axis of the beam at the point of interest during calibration. Thereafter, changes in the polarization phase, and in the angle of the major axis, at the point of interest can be monitored by measuring the changes in these same parameters at the diagnostic point.

  12. Optimization of polarizer angles for measurements of the degree and angle of linear polarization for linear polarizer-based polarimeters

    NASA Astrophysics Data System (ADS)

    Xia, Run-Qiu; Wang, Xia; Jin, Wei-Qi; Liang, Jian-An

    2015-10-01

    Linear polarizer-based polarimeters that measure the degree of linear polarization (DoLP) and the angle of polarization (AoP) were considered in this study. Variances of DoLP and AoP of the region of interest (ROI) to be measured were analyzed using a statistical method. To simplify the calculation, only additive noise and shot noise were considered. Optimized combinations of the polarizers that can minimize the variances of DoLP and AoP were determined by investigating the variances of different polarizer combinations. Several regularities were found when analyzing the data obtained from the optimized combinations. Some variables in the combinations are inversely proportional to the cube or square root of the signal-to-noise ratio of the output signals from sensors without polarizer filtering, and these variables are functions of the DoLP of the ROI to be measured.

  13. Spirit 360-Degree View on Sol 409 (polar)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on Spirit's 409th martian day, or sol (Feb. 26, 2005). Spirit had driven 2 meters (7 feet) on this sol to get in position on 'Cumberland Ridge' for looking into 'Tennessee Valley' to the east. This location is catalogued as Spirit's Site 108. Rover-wheel tracks from climbing the ridge are visible on the right. The summit of 'Husband Hill' is at the center, to the south. This view is presented in a polar projection with geometric and brightness seam correction.

  14. ON THE RELIABILITY OF POLARIZATION ESTIMATION USING ROTATION MEASURE SYNTHESIS

    SciTech Connect

    Macquart, J.-P.; Ekers, R. D.; Johnston-Hollitt, M.

    2012-05-10

    We benchmark the reliability of the rotation measure (RM) synthesis algorithm using the 1005 Centaurus A field sources of Feain et al. The RM synthesis solutions are compared with estimates of the polarization parameters using traditional methods. This analysis provides verification of the reliability of RM synthesis estimates. We show that estimates of the polarization parameters can be made at lower signal-to-noise ratio (S/N) if the range of RMs is bounded, but reliable estimates of individual sources with unusual RMs require unconstrained solutions and higher S/N. We derive from first principles the statistical properties of the polarization amplitude associated with RM synthesis in the presence of noise. The amplitude distribution depends explicitly on the amplitude of the underlying (intrinsic) polarization signal. Hence, it is necessary to model the underlying polarization signal distribution in order to estimate the reliability and errors in polarization parameter estimates. We introduce a Bayesian method to derive the distribution of intrinsic amplitudes based on the distribution of measured amplitudes. The theoretically derived distribution is compared with the empirical data to provide quantitative estimates of the probability that an RM synthesis solution is correct as a function of S/N. We provide quantitative estimates of the probability that any given RM synthesis solution is correct as a function of measured polarized amplitude and the intrinsic polarization amplitude compared to the noise.

  15. Compact polarization rotators for integrated polarization diversity in InP-based waveguides.

    PubMed

    Beggs, Daryl M; Midrio, Michele; Krauss, Thomas F

    2007-08-01

    We present the design, fabrication, and operation of a polarization converter based on angled waveguides in the InP/InGaAsP material system. By combining design elements from mode evolution and birefringent devices, the total device length is kept short (less than 50 microm) and the insertion efficiency high at 81%+/-19%, which corresponds to an insertion loss of 1 dB. Devices operate broadband, i.e., the polarization conversion exceeds 15 dB over a 100 nm wavelength range. A polarization rotator with these specifications is a prime candidate for use in an integrated polarization diversity scheme. PMID:17671575

  16. Compact polarization rotators for integrated polarization diversity in InP-based waveguides

    NASA Astrophysics Data System (ADS)

    Beggs, Daryl M.; Midrio, Michele; Krauss, Thomas F.

    2007-08-01

    We present the design, fabrication, and operation of a polarization converter based on angled waveguides in the InP/InGaAsP material system. By combining design elements from mode evolution and birefringent devices, the total device length is kept short (less than 50μm) and the insertion efficiency high at 81%+/-19%, which corresponds to an insertion loss of 1dB. Devices operate broadband, i.e., the polarization conversion exceeds 15dB over a 100nm wavelength range. A polarization rotator with these specifications is a prime candidate for use in an integrated polarization diversity scheme.

  17. Protein rotational motion in solution measured by polarized fluorescence depletion.

    PubMed Central

    Yoshida, T M; Barisas, B G

    1986-01-01

    A microscope-based system is described for directly measuring protein rotational motion in viscous environments such as cell membranes by polarized fluorescence depletion (PFD). Proteins labeled with fluorophores having a high quantum yield for triplet formation, such as eosin isothiocyanate (EITC), are examined anaerobically in a fluorescence microscope. An acousto-optic modulator generates a several-microsecond pulse of linearly polarized light which produces an orientationally-asymmetric depletion of ground state fluorescence in the sample. When the sample is then probed with light polarized parallel to the excitation pulse, fluorescence recovers over 0-1,000 microseconds as the sum of two exponentials. One exponential corresponds to triplet decay and the other to the rotational relaxation. An exciting pulse perpendicular to the probe beam is then applied. Fluorescence recovery following this pulse is the difference of the same two exponentials. Equations for fluorescence recovery kinetics to be expected in various experimentally significant cases are derived. Least-squares analysis using these equations then permits the triplet lifetime and rotational correlation time to be determined directly from PFD data. Instrumentation for PFD measurements is discussed that permits photobleaching recovery measurements of lateral diffusion coefficients using the same microscope system. With this apparatus, both rotational and translational diffusion coefficients (Dr, Dt) were measured for EITC-labeled bovine serum albumin in glycerol solutions. Values obtained for Dr and Dt are discussed in light of both the PFD models and the experimental system. PMID:3730506

  18. Rotational polarities of sudden impulses in the magnetotail lobe

    NASA Technical Reports Server (NTRS)

    Kawano, H.; Yamamoto, T.; Kokubun, S.; Lepping, R. P.

    1992-01-01

    A sudden impulse (SI) is a sudden change in the magnetic field strength which is caused by a change in the solar wind pressure and is observed throughout the magnetosphere. In this report we have examined the rotations of the magnetic field vectors at times of SIs in the magnetotail lobe, by using IMP 6, 7, and 8 magnetometer data. The following properties have been found: (1) at the time of SI the arrowhead of the magnetic vector tends to rotate in one plane; (2) the plane of rotation tends to include the unperturbed magnetic field vector; (3) the plane of rotation tends to be aligned with the radial direction from the magnetotail axis; and (4) the magnetic vectors have a particular rotational polarity: when the plane of rotation is viewed so that the Sun is to the right of the viewed plane and the magnetotail axis is to the bottom, the arrowhead of the vector tends to rotate counterclockwise in this plane. These magnetic vector properties are consistent with those expected when part of an increase in solar wind lateral pressure squeezes the magnetotail axisymmetrically while moving tailward.

  19. Earth rotation and polar motion - Measurements and implications

    NASA Technical Reports Server (NTRS)

    Dickey, J. O.; Eubanks, T. M.

    1985-01-01

    Several methods used to measure earth rotation and polar motion are discussed. The development of techniques for combining smoothing, and intercomparing geodetic measurements is described. Emphasis is given to measurements obtained since 1980 using VLBI, lunar laser ranging (LLR) and satellite laser ranging (SLR) techniques. The calculation of atmospheric angular momentum (AAM) excitation functions is outlined, and a comparison of AAM excitation functions with variations in the length of day (LOD) and polar motion data is presented. The geophysical implications of geodetic measurements are addressed.

  20. NON-ZEEMAN CIRCULAR POLARIZATION OF MOLECULAR ROTATIONAL SPECTRAL LINES

    SciTech Connect

    Houde, Martin; Jones, Scott; Rajabi, Fereshte; Hezareh, Talayeh

    2013-02-10

    We present measurements of circular polarization from rotational spectral lines of molecular species in Orion KL, most notably {sup 12}CO (J = 2 {yields} 1), obtained at the Caltech Submillimeter Observatory with the Four-Stokes-Parameter Spectral Line Polarimeter. We find levels of polarization of up to 1%-2% in general; for {sup 12}CO (J = 2 {yields} 1) this level is comparable to that of linear polarization also measured for that line. We present a physical model based on resonant scattering in an attempt to explain our observations. We discuss how slight differences in scattering amplitudes for radiation polarized parallel and perpendicular to the ambient magnetic field, responsible for the alignment of the scattering molecules, can lead to the observed circular polarization. We also show that the effect is proportional to the square of the magnitude of the plane of the sky component of the magnetic field and therefore opens up the possibility of measuring this parameter from circular polarization measurements of Zeeman insensitive molecules.

  1. Ultra-wideband and high-efficiency polarization rotator based on metasurface

    NASA Astrophysics Data System (ADS)

    Jia, Yongtao; Liu, Ying; Zhang, Wenbo; Gong, Shuxi

    2016-08-01

    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.

  2. Type Synthesis of Two-Degrees-of-Freedom Rotational Parallel Mechanism with Two Continuous Rotational Axes

    NASA Astrophysics Data System (ADS)

    Xu, Yundou; Zhang, Dongsheng; Wang, Min; Yao, Jiantao; Zhao, Yongsheng

    2016-04-01

    The two-rotational-degrees-of-freedom(2R) parallel mechanism(PM) with two continuous rotational axes(CRAs) has a simple kinematic model. It is therefore easy to implement trajectory planning, parameter calibration, and motion control, which allows for a variety of application prospects. However, no systematic analysis on structural constraints of the 2R-PM with two CRAs has been performed, and there are only a few types of 2R-PM with two CRAs. Thus, a theory regarding the type synthesis of the 2R-PM with two CRAs is systematically established. First, combining the theories of reciprocal screw and space geometry, the spatial arrangement relationships of the constraint forces applied to the moving platform by the branches are explored, which give the 2R-PM two CRAs. The different distributions of the constraint forces in each branch are also studied. On the basis of the obtained structural constraints of branches, and considering the geometric relationships of constraint forces in each branch, the appropriate kinematic chains are constructed. Through the reasonable configuration of branch kinematic chains corresponding to every structural constraint, a series of new 2R-PMs with two CRAs are finally obtained.

  3. Role of rotational degrees of freedom in heavy-ion collisions

    SciTech Connect

    Moretto, L.G.

    1982-04-01

    The degrees of freedom affected by the angular momentum are identified. The relevance of the equilibrium fluctuations in a diffusive evolution of the system is discussed. The statistical limit is described and chosen as a reference for comparing with experiment. The rigid rotation regime is shown to be reached in a variety of reactions. The fragment spin alignment is measured from ..gamma..-ray multiplicities and anisotropies as well as from sequential fission angular distributions. Good agreement is obtained with the statistical model for the P/sub zz/ component of the polarization tensor. The P/sub xy/ component seems also to reach the statistical limit at large Q-value. The effect of shells on the angular momentum transferred to the fragments and on its misalignment is discussed theoretically and specific predictions are made.

  4. The role of rotation and polar-cap currents on pulsar radio emission and polarization

    SciTech Connect

    Kumar, D.; Gangadhara, R. T. E-mail: ganga@iiap.res.in

    2013-06-01

    Perturbations such as rotation and polar-cap current (PC-current) have been believed to greatly affect the pulsar radio emission and polarization. The two effects have not been considered simultaneously in the literature; each one of these has been considered separately, and a picture has been deduced by simply superposing them, but such an approach can lead to spurious results. Hence, by considering pulsar rotation and PC-current perturbations together instead of one at a time, we have developed a single particle curvature radiation model, which is expected to be much more realistic. By simulating a set of typical pulse profiles, we have made an attempt to explain most of the observational results of pulsar radio emission and polarization. The model predicts that due to the perturbations the leading side component can become either stronger or weaker than the corresponding trailing one in any given cone, depending on the passage of the sight line and modulation (nonuniform source distribution). Further, we find that the phase delay of the polarization angle inflection point with respect to the core component greatly depends on the viewing geometry. The correlation between the sign reversal of circular polarization and the polarization angle swing in the case of core-dominated pulsars becomes obscure once the perturbations and modulation become significant. However, the correlation between the negative circular polarization and the increasing polarization angle and vice versa is very clear in the case of conal-double pulsars. The 'kinky'-type distortions in polarization angle swing could be due to the incoherent superposition of modulated emission in the presence of strong perturbations.

  5. A method to polarize stored antiprotons to a high degree.

    PubMed

    Rathmann, F; Lenisa, P; Steffens, E; Contalbrigo, M; Dalpiaz, P F; Kacharava, A; Lehrach, A; Lorentz, B; Maier, R; Prasuhn, D; Ströher, H

    2005-01-14

    Polarized antiprotons can be produced in a storage ring by spin-dependent interaction in a purely electron-polarized hydrogen gas target. The polarizing process is based on spin transfer from the polarized electrons of the target atoms to the orbiting antiprotons. After spin filtering for about two beam lifetimes at energies T approximately equal 40-170 MeV using a dedicated large acceptance ring, the antiproton beam polarization would reach P=0.2-0.4. Polarized antiprotons would open new and unique research opportunities for spin-physics experiments in p(-) p interactions. PMID:15698088

  6. Magnetic-Field-Induced Rotation of Polarized Light Emission from Monolayer WS_{2}.

    PubMed

    Schmidt, Robert; Arora, Ashish; Plechinger, Gerd; Nagler, Philipp; Granados Del Águila, Andrés; Ballottin, Mariana V; Christianen, Peter C M; Michaelis de Vasconcellos, Steffen; Schüller, Christian; Korn, Tobias; Bratschitsch, Rudolf

    2016-08-12

    We control the linear polarization of emission from the coherently emitting K^{+} and K^{-} valleys (valley coherence) in monolayer WS_{2} with an out-of-plane magnetic field of up to 25 T. The magnetic-field-induced valley Zeeman splitting causes a rotation of the emission polarization with respect to the excitation by up to 35° and reduces the polarization degree by up to 16%. We explain both of these phenomena with a model based on two noninteracting coherent two-level systems. We deduce that the coherent light emission from the valleys decays with a time constant of τ_{c}=260  fs. PMID:27563997

  7. Ultrashort polarization rotator based on cross-symmetry waveguide

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Dong, Jianji

    2016-05-01

    An ultrashort polarization rotator (PR) based on cross-symmetry waveguide is proposed and discussed. At the operating wavelength of 1 . 55 μ m , the presented PR has a small conversion length of 3 . 3 μ m . The polarization conversion efficiency (PCE) is 99 . 8 % (TE-TM) and 99 . 97 % (TM-TE). The PR can achieve rather high conversion efficiency (> 97 %) over a broad bandwidth (1450 - 1700 nm). The cross-symmetry structure can significantly improve the extinction ratio. The extinction ratio is 27 . 7 dB (TE-TM) and 35 . 9 dB (TM-TE) with the insertion loss of 0 . 28 dB . The fabrication tolerances for the waveguide for both transverse and horizontal directions are also studied.

  8. Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements.

    PubMed

    Olivier, Michel; Gagnon, Marc-Daniel; Habel, Joé

    2016-01-01

    When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques. PMID:26967924

  9. Three-parameter error analysis method based on rotating coordinates in rotating birefringent polarizer system

    SciTech Connect

    Cao, Junjie; Jia, Hongzhi

    2015-11-15

    We propose error analysis using a rotating coordinate system with three parameters of linearly polarized light—incidence angle, azimuth angle on the front surface, and angle between the incidence and vibration planes—and demonstrate the method on a rotating birefringent prism system. The transmittance and angles are calculated plane-by-plane using a birefringence ellipsoid model and the final transmitted intensity equation is deduced. The effects of oblique incidence, light interference, beam convergence, and misalignment of the rotation and prism axes are discussed. We simulate the entire error model using MATLAB and conduct experiments based on a built polarimeter. The simulation and experimental results are consistent and demonstrate the rationality and validity of this method.

  10. Three-parameter error analysis method based on rotating coordinates in rotating birefringent polarizer system.

    PubMed

    Cao, Junjie; Jia, Hongzhi

    2015-11-01

    We propose error analysis using a rotating coordinate system with three parameters of linearly polarized light--incidence angle, azimuth angle on the front surface, and angle between the incidence and vibration planes--and demonstrate the method on a rotating birefringent prism system. The transmittance and angles are calculated plane-by-plane using a birefringence ellipsoid model and the final transmitted intensity equation is deduced. The effects of oblique incidence, light interference, beam convergence, and misalignment of the rotation and prism axes are discussed. We simulate the entire error model using MATLAB and conduct experiments based on a built polarimeter. The simulation and experimental results are consistent and demonstrate the rationality and validity of this method. PMID:26628116

  11. 360-degree table-top display with rotating transmissive screen

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Soo; Jeon, Hosung; Lee, Sang Kil; Kim, Hwi; Hahn, Joonku

    2015-03-01

    Three-dimensional (3D) display usually provides binocular disparity to observer. To construct 360degree table-top display, lots of views are required. In order to display a large amount of views to observer, time-multiplexing technique is applied. We suggest a new structure for view-sequential 360-degree table-top display system. In my system, a transmissive screen is used and digital micromirror device (DMD) image is projected on it. This system defines the direction of bundle of rays to configure the sequential view. It has some advantages resulting from the transmissive flat screen. When the transmissive screen is used instead of the reflective one, the light power efficiency is improved. Moreover, the arrangement of the pixel is more uniform when the screen is flat instead of a static conic screen. We construct a table-top display with about 288views around 360degree and its feasibilities are confirmed.

  12. Continuum estimates of rotational dielectric friction and polar solvation

    SciTech Connect

    Maroncelli, M.

    1997-01-01

    Dynamical solvation data recently obtained with the probe solute coumarin 153 are used to test the reliability of dielectric continuum models for estimating dielectric friction effects. In particular, the predictions of the Nee{endash}Zwanzig theory of rotational dielectric friction are examined in some detail. The analysis undertaken here uncovers an error made in virtually all previous applications of the Nee{endash}Zwanzig formalism. The error involves neglect of the solvent{close_quote}s electronic polarizability when calculating dielectric friction constants. In highly polar solvents the effect of this neglect is shown to be minor, so that the results of past studies should not be appreciably altered. However, in weakly polar and especially in nondipolar solvents, the proper inclusion of electronic polarizability terms is essential. The equivalence between the Nee{endash}Zwanzig theory of dielectric friction and more general continuum treatments of polar solvation dynamics is also demonstrated. This equivalence enables the use of solvation data to test the reliability of the Nee{endash}Zwanzig description of electrical interactions between a solute and solvent that form the core of this and related continuum theories of dielectric friction. Comparisons to experimental data show that, with the important exception of nondipolar solvents, such continuum treatments provide reasonably accurate ({plus_minus}40{percent}) predictors of time-dependent solvation and/or dielectric friction. {copyright} {ital 1997 American Institute of Physics.}

  13. RoboPol: optical polarization-plane rotations and flaring activity in blazars

    NASA Astrophysics Data System (ADS)

    Blinov, D.; Pavlidou, V.; Papadakis, I. E.; Hovatta, T.; Pearson, T. J.; Liodakis, I.; Panopoulou, G. V.; Angelakis, E.; Baloković, M.; Das, H.; Khodade, P.; Kiehlmann, S.; King, O. G.; Kus, A.; Kylafis, N.; Mahabal, A.; Marecki, A.; Modi, D.; Myserlis, I.; Paleologou, E.; Papamastorakis, I.; Pazderska, B.; Pazderski, E.; Rajarshi, C.; Ramaprakash, A.; Readhead, A. C. S.; Reig, P.; Tassis, K.; Zensus, J. A.

    2016-04-01

    We present measurements of rotations of the optical polarization of blazars during the second year of operation of RoboPol, a monitoring programme of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events, and we analyse the large set of rotation events discovered in two years of observation. We investigate patterns of variability in the polarization parameters and total flux density during the rotation events and compare them to the behaviour in a non-rotating state. We have searched for possible correlations between average parameters of the polarization-plane rotations and average parameters of polarization, with the following results: (1) there is no statistical association of the rotations with contemporaneous optical flares; (2) the average fractional polarization during the rotations tends to be lower than that in a non-rotating state; (3) the average fractional polarization during rotations is correlated with the rotation rate of the polarization plane in the jet rest frame; (4) it is likely that distributions of amplitudes and durations of the rotations have physical upper bounds, so arbitrarily long rotations are not realized in nature.

  14. THE ROTATION PROFILE OF SOLAR MAGNETIC FIELDS BETWEEN {+-}60 Degree-Sign LATITUDES

    SciTech Connect

    Shi, X. J.; Xie, J. L.

    2013-08-10

    Through a cross-correlation analysis of the Carrington synoptic maps of solar photospheric magnetic fields from Carrington Rotation Nos. 1625 to 2129 (from 1975 February to 2012 October), the sidereal rotation rates of solar magnetic fields between {+-}60 Degree-Sign latitudes are investigated. It seems that the temporal variation of rotation rates should be related to the solar cycle phase. The rotation profile of magnetic fields is obtained: the sidereal rotation rates decrease from the equator to mid-latitude and reach their minimum values of about 13.16 deg day{sup -1} (13.17 deg day{sup -1}) at 53 Degree-Sign (54 Degree-Sign ) latitude in the northern (southern) hemisphere, then increase toward higher latitudes. This rotation profile is different from the differential rotation law obtained by Snodgrass from a cross-correlation analysis of daily magnetograms, in which the rotation rates show a steep decrease from the equator to the poles. However, it is much closer to the quasi-rigid rotation law derived by Stenflo from an auto-correlation analysis of daily magnetograms. Some possible interpretations are discussed for the resulting rotation profile.

  15. Laser Oscillator Incorporating a Wedged Polarization Rotator and a Porro Prism as Cavity Mirror

    NASA Technical Reports Server (NTRS)

    Li, Steven

    2011-01-01

    A laser cavity was designed and implemented by using a wedged polarization rotator and a Porro prism in order to reduce the parts count, and to improve the laser reliability. In this invention, a z-cut quartz polarization rotator is used to compensate the wavelength retardance introduced by the Porro prism. The polarization rotator rotates the polarization of the linear polarized beam with a designed angle that is independent of the orientation of the rotator. This unique property was used to combine the retardance compensation and a Risley prism to a single optical component: a wedged polarization rotator. This greatly simplifies the laser alignment procedure and reduces the number of the laser optical components.

  16. Arc-Polarized, Nonlinear Alfven Waves and Rotational Discontinuities: Directions of Propogation?

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Ho, C. M.; Sakurai, R.; Arballo, J. K.; Riley, P.; Balogh, A.

    1996-01-01

    Large amplitude, noncompressive Alfven waves and rotational discontinuities are shown to be arc-polarized. The slowly rotating Alfven wave portion plus the fast rotating discontinuity comprise 360(deg) in phase rotation. The magnetic field vector perturbation lies in a plane. There are two (or more) possible interpretations to the observations.

  17. Influence of neglected covariances on the estimation of Earth rotation parameters, geophysical excitation functions and second degree gravity field coefficients

    NASA Astrophysics Data System (ADS)

    Heiker, Andrea; Kutterer, Hansjörg

    2010-05-01

    The Earth rotation variability is redundantly described by the combination of Earth rotation parameters (polar motion and length of day), geophysical excitation functions and second degree gravity field coefficients. There exist some publications regarding the comparison of the Earth rotation parameters and excitation functions. However, most authors do not make use of the redundancy. In addition, existing covariances between the input parameters are not considered. As shown in previous publications we use the redundancy for the independent mutual validation of the Earth rotation parameters, excitation functions and second degree gravity field coefficients based on an extended Gauss-Markov model and least-squares adjustment. The work regarding the mutual validation is performed within the project P9 "Combined analysis and validation of Earth rotation models and observations" of the research Unit FOR 584 ("Earth rotation and global dynamic processes") which is funded by the German Research Unit (DFG); see also abstract "Combined Analysis and Validation of Earth Rotation Models and Observations". The adjustment model is determined at first by the joint functional relations between the parameters and second by the stochastic model of the input data. A variance-covariance component estimation is included in the adjustment model. The functional model is based on the linearized Euler-Liouville equation. The construction of an appropriate stochastic model is prevented in practice by insufficient knowledge on variances and covariances. However, some numerical results derived from arbitrarily chosen stochastic models indicate that the stochastic model may be crucial for a correct estimation. The missing information is approximated by analyzing the input data. Synthetic variance-covariance matrices are constructed by considering empirical auto- and cross-correlation functions. The influence of neglected covariances is quantified and discussed by comparing the results derived

  18. General relativistic x ray (UV) polarization rotations as a quantitative test for black holes

    NASA Technical Reports Server (NTRS)

    Stark, Richard F.

    1989-01-01

    It is now 11 years since a potentially easily observable and quantitative test for black holes using general relativistic polarization rotations was proposed (Stark and Connors 1977, and Connors and Stark 1977). General relativistic rotations of the x ray polarization plane of 10 to 100 degrees with x ray energy (between 1 and 100 keV) are predicted for black hole x ray binaries. (Classically, by symmetry, there is no rotation.) Unfortunately, x ray polarimetry has not been taken sufficiently seriously during this period, and this test has not yet been performed. A similar (though probably less clean) effect is expected in the UV for supermassive black holes in some quasars active galactic nuclei. Summarizing: (1) a quantitative test (proposed in 1977) for black holes exists; (2) x ray polarimetry of galactic x ray binaries sensitive to at least 1/2 percent between 1 keV and 100 keV is needed (polarimetry in the UV of quasars and AGN will also be of interest); and (3) proportional counters using timerise discrimination were shown in laboratory experiments able to perform x ray polarimetry and this and other methods need to be developed.

  19. Rotational inertia of continents: A proposed link between polar wandering and plate tectonics

    USGS Publications Warehouse

    Kane, M.F.

    1972-01-01

    A mechanism is proposed whereby displacement between continents and the earth's pole of rotation (polar wandering) gives rise to latitudinal transport of continental plates (continental drift) because of their relatively greater rotational inertia. When extended to short-term polar wobble, the hypothesis predicts an energy change nearly equivalent to the seismic energy rate.

  20. A technique for measuring vertically and horizontally polarized microwave brightness temperatures using electronic polarization-basis rotation

    NASA Technical Reports Server (NTRS)

    Gasiewski, Albin J.

    1992-01-01

    This technique for electronically rotating the polarization basis of an orthogonal-linear polarization radiometer is based on the measurement of the first three feedhorn Stokes parameters, along with the subsequent transformation of this measured Stokes vector into a rotated coordinate frame. The technique requires an accurate measurement of the cross-correlation between the two orthogonal feedhorn modes, for which an innovative polarized calibration load was developed. The experimental portion of this investigation consisted of a proof of concept demonstration of the technique of electronic polarization basis rotation (EPBR) using a ground based 90-GHz dual orthogonal-linear polarization radiometer. Practical calibration algorithms for ground-, aircraft-, and space-based instruments were identified and tested. The theoretical effort consisted of radiative transfer modeling using the planar-stratified numerical model described in Gasiewski and Staelin (1990).

  1. Degree of polarization and source counts of faint radio sources from Stacking Polarized intensity

    SciTech Connect

    Stil, J. M.; George, S. J.; Keller, B. W.; Taylor, A. R.

    2014-06-01

    We present stacking polarized intensity as a means to study the polarization of sources that are too faint to be detected individually in surveys of polarized radio sources. Stacking offers not only high sensitivity to the median signal of a class of radio sources, but also avoids a detection threshold in polarized intensity, and therefore an arbitrary exclusion of sources with a low percentage of polarization. Correction for polarization bias is done through a Monte Carlo analysis and tested on a simulated survey. We show that the nonlinear relation between the real polarized signal and the detected signal requires knowledge of the shape of the distribution of fractional polarization, which we constrain using the ratio of the upper quartile to the lower quartile of the distribution of stacked polarized intensities. Stacking polarized intensity for NRAO VLA Sky Survey (NVSS) sources down to the detection limit in Stokes I, we find a gradual increase in median fractional polarization that is consistent with a trend that was noticed before for bright NVSS sources, but is much more gradual than found by previous deep surveys of radio polarization. Consequently, the polarized radio source counts derived from our stacking experiment predict fewer polarized radio sources for future surveys with the Square Kilometre Array and its pathfinders.

  2. The tidal-rotational shape of the Moon and evidence for polar wander.

    PubMed

    Garrick-Bethell, Ian; Perera, Viranga; Nimmo, Francis; Zuber, Maria T

    2014-08-14

    The origin of the Moon's large-scale topography is important for understanding lunar geology, lunar orbital evolution and the Moon's orientation in the sky. Previous hypotheses for its origin have included late accretion events, large impacts, tidal effects and convection processes. However, testing these hypotheses and quantifying the Moon's topography is complicated by the large basins that have formed since the crust crystallized. Here we estimate the large-scale lunar topography and gravity spherical harmonics outside these basins and show that the bulk of the spherical harmonic degree-2 topography is consistent with a crust-building process controlled by early tidal heating throughout the Moon. The remainder of the degree-2 topography is consistent with a frozen tidal-rotational bulge that formed later, at a semi-major axis of about 32 Earth radii. The probability of the degree-2 shape having both tidal-heating and frozen shape characteristics by chance is less than 1%. We also infer that internal density contrasts eventually reoriented the Moon's polar axis by 36 ± 4°, to the configuration we observe today. Together, these results link the geology of the near and far sides, and resolve long-standing questions about the Moon's large-scale shape, gravity and history of polar wander. PMID:25079322

  3. Femtosecond Raman induced polarization spectroscopy studies of coherent rotational dynamics in molecular fluids

    SciTech Connect

    Morgen, M M

    1997-05-01

    We develop a polarization-sensitive femtosecond pump probe technique, Raman induced polarization spectroscopy (RIPS), to study coherent rotation in molecular fluids. By observing the collisional dephasing of the coherently prepared rotational states, we are able to extract information concerning the effects of molecular interactions on the rotational motion. The technique is quite sensitive because of the zero background detection method, and is also versatile due to its nonresonant nature.

  4. Direct formulation of a 4-node hybrid shell element with rotational degrees of freedom

    NASA Technical Reports Server (NTRS)

    Aminpour, Mohammad A.

    1990-01-01

    A simple 4-node assumed-stress hybrid quadrilateral shell element with rotational or drilling degrees of freedom is formulated. The element formulation is based directly on a 4-node element. This direct formulation requires fewer computations than a similar element that is derived from an internal 8-node isoparametric element in which the midside degrees of freedom are eliminated in favor of rotational degree of freedom at the corner nodes. The formulation is based on the principle of minimum complementary energy. The membrane part of the element has 12 degrees of freedom including rotational degrees of freedom. The bending part of the element also has 12 degrees of freedom. The bending part of the quadratic variations for both in-plane and out-of-plane displacement fields and linear variations for both in-plane and out-of-plane rotation fields are assumed along the edges of the element. The element Cartesian-coordinate system is chosen such as to make the stress field invariant with respect to node numbering. The membrane part of the stress field is based on a 9-parameter equilibrating stress field, while the bending part is based on a 13-parameter equilibrating stress field. The element passes the patch test, is nearly insensitive to mesh distortion, does not lock, possesses the desirable invariance properties, has no spurious modes, and produces accurate and reliable results.

  5. Realization of a compact polarization splitter-rotator on silicon.

    PubMed

    Dai, Daoxin; Wu, Hao

    2016-05-15

    A novel compact polarization splitter-rotator (PSR) is proposed and realized with silicon-on-insulator nanowires. The present PSR consists of an adiabatic taper, an asymmetric directional coupler (ADC), and a multimode interference (MMI) mode filter. The adiabatic taper enables an efficient mode conversion from the launched TM0 mode to the TE1 mode in a wide waveguide, which is then coupled to the TE0 mode of a narrow waveguide through the ADC. Meanwhile, the launched TE0 mode does not have mode conversion and outputs from the through port directly. The MMI mode filter is cascaded at the through port to filter out the residual power of the TE1 mode so that the extinction ratio of the PSR is improved greatly. The total length of the PSR is ∼70  μm and the fabricated PSR has an extinction ratio of ∼20  dB over a broadband ranging from 1547 to 1597 nm. PMID:27176999

  6. Soliton polarization rotation and switching in type II second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Mollame, Riccardo; Trillo, Stefano; Assanto, Gaetano

    1996-12-01

    We predict that solitary waves of dispersive type II second-harmonic generation may experience large uniform nonlinear polarization rotations. The nonlinear medium followed by a polarization analyzer permits undistorted all-optical switching of pulses controlled by the input polarization.

  7. Experimentally determined characteristics of the degree of polarization of backscattered light from polystyrene sphere suspensions

    NASA Astrophysics Data System (ADS)

    Sun, Ping; Ma, Yongchao; Liu, Wei; Xu, Chengwei; Sun, Xiaochun

    2013-05-01

    The degree of polarization (DOP) can be used to characterize the polarization-maintaining ability of a beam of polarized light propagating through a turbid medium. Experiments on polystyrene (PST) sphere suspensions show that, the linearly polarized light propagating through the PST sphere suspension of Rayleigh scatterers has better polarization-maintaining ability, whereas the circularly polarized light propagating through the PST sphere suspension of Mie scatterers has better polarization-maintaining ability. Moreover, helicity flipping occurs to the circularly polarized light propagating in the extremely weak PST sphere suspensions or on the surface of suspensions. In addition, the DOP is dependent on the wavelength of incident light. The results can be helpful to image in turbid media by use of diffuse backscattered light.

  8. Dual-channel chaos synchronization and communication based on unidirectionally coupled VCSELs with polarization-rotated optical feedback and polarization-rotated optical injection.

    PubMed

    Liu, Jiao; Wu, Zheng-Mao; Xia, Guang-Qiong

    2009-07-20

    A novel dual-channel chaotic synchronization configuration is proposed. This system is constructed on the basis of two unidirectionally coupled vertical-cavity surface-emitting lasers (VCSELs), where a VCSEL subjected to polarization-rotated optical feedback is used as a transmitter and the other VCSEL subjected to polarization-rotated optical injection is used as a receiver. The synchronization and communication performances of such a system are numerically investigated. The results show that, similar to polarization-preserved coupled system with polarization-preserved optical feedback at the T-VCSEL port and polarization-preserved optical injection at the R-VCSEL port, such polarization-rotated coupled system can also realize complete synchronization between each pair of linear polarization (LP) modes and the total output of T-VCSEL and R-VCSEL. Compared with the polarization-preserved coupled system, this proposed system has higher tolerance to mismatched parameters. Furthermore, the average intensities of two orthogonal LP modes are almost the same so that this framework may be used to realize dual-channel chaos communication. Under the additive chaos modulation (ACM) encryption scheme, the encoded messages can be successfully extracted for both of orthogonal LP modes. PMID:19654666

  9. Transient stability enhancement of electric power generating systems by 120-degree phase rotation

    DOEpatents

    Cresap, Richard L.; Taylor, Carson W.; Kreipe, Michael J.

    1982-01-01

    A method and system for enhancing the transient stability of an intertied three-phase electric power generating system. A set of power exporting generators (10) is connected to a set of power importing generators (20). When a transient cannot be controlled by conventional stability controls, and imminent loss of synchronism is detected (such as when the equivalent rotor angle difference between the two generator sets exceeds a predetermined value, such as 150 degrees), the intertie is disconnected by circuit breakers. Then a switch (30) having a 120-degree phase rotation, or a circuit breaker having a 120-degree phase rotation is placed in the intertie. The intertie is then reconnected. This results in a 120-degree reduction in the equivalent rotor angle difference between the two generator sets, making the system more stable and allowing more time for the conventional controls to stabilize the transient.

  10. A near-transparent 90∘ polarization rotator with an array of L-shaped holes inside a glass cube

    NASA Astrophysics Data System (ADS)

    Liao, Yan-Lin; Zhao, Yan; Lu, He-Ping

    2016-07-01

    We report a near-transparent 90∘ polarization rotator by using a single-layer microstructure. The co-polarization light has been suppressed by using destructive interference. At the same time, the transmission of cross-polarization light has been improved with inference effect between surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs). This efficient polarization rotation mechanism may be very useful in designing polarization rotators.

  11. A white-light amplitude interferometer with 180-degree rotational shear

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.

    1978-01-01

    The paper reports on the fabrication, alignment, and test techniques of an equal-path, wave-front, folding amplitude interferometer with 180-degree rotational shear. The device may be used for measuring atmospheric phase-perturbing properties and designing optical filters used in processing spatial information. The instrument has been used to photograph the Michelson Stellar interferometer fringes.

  12. Degree of polarization fading of light passing through birefringent medium with optical axis variation

    NASA Astrophysics Data System (ADS)

    Makowski, Piotr L.; Domański, Andrzej W.

    2010-09-01

    Numerical implementation of Mueller-Stokes matrix calculus for polychromatic light is used to analyze and plainly illustrate polarization properties of multi-section linearly birefringent systems illuminated by the light of any spectrum profile. Numerical investigations are preceded by a detailed review of known concepts for modeling the depolarization phenomenon in anisotropic media. The numerical study examines efficiency of the Lyot depolarizer system undergoing variations from the optimal configuration. In addition, the power spectrum density profile and intrinsic polarization state of light passing through the system are considered as interesting degrees of freedom. The comparative analysis makes use of the degree of polarization and the depolarization index diagrams.

  13. Rotation of the polarization vector from distant radio galaxies in the perturbed FRW metric

    NASA Astrophysics Data System (ADS)

    Chakrabarty, Sankha Subhra

    2016-06-01

    Analysis of the correlation between the angular positions of distant radio galaxies on the sky and the orientations of their polarization vectors with respect to their major axes indicates a dipolar anisotropy in the large scale. We consider a single mode of large-scale scalar perturbation to the FRW metric. Using Newman-Penrose formalism, we calculate the rotation of the galaxy major axis with respect to the polarization vector as the elliptic image and the polarization vector are carried through the perturbed spacetime. The dependence of the rotation on the polar angular coordinate of the galaxy is qualitatively similar to the claimed dipole pattern.

  14. Measurement of the degree of polarization of the spectra from laser produced recombining Al plasmas.

    PubMed

    Kim, Jaehoon; Kim, Dong-Eon

    2002-07-01

    Using a polarization-resolved UV-visible spectrometer, the degree of polarization of the spectra from laser produced Al plasmas was measured. The polarization resolution was achieved by using either a dichroic polarizer or a calcite crystal. The degree of polarization of Al III 4s(2)S(1/2)-4p(2)P(o)(3/2) transition at 569.66 nm was measured at different positions from a target surface. The degree of polarization was observed to be 2.1+/-0.13% at a distance of 220 microm from the target and decreased as the distance from the target increased, vanishing at a distance of about 1.3 mm from the target. To avoid the possible error due to the shot-to-shot variation of the line intensity, a calcite crystal was used to simultaneously observe the two polarization components, obtaining a similar result. The electron temperature of about 3 eV and the density of 2 x 10(17) cm(-3) measured spectroscopically indicates that the plasma was in the recombining phase. This is a report on the observation of the polarization of a transition in a laser-produced recombining Al plasma. PMID:12241524

  15. Correction for nonlinearity and polarization-dependent sensitivity in the detection system of rotating analyzer ellipsometers.

    PubMed

    Russev, S H

    1989-04-15

    Systematic errors due to nonlinearity and polarization-dependent sensitivity in the detection system of rotating analyzer ellipsometers are described. Post Fourier analysis procedures for detection and correction of these effects are presented. PMID:20548687

  16. Progress Towards the Detection of Faraday Rotation on Spin Polarized 3He

    NASA Astrophysics Data System (ADS)

    Abney, Josh; Broering, Mark; Korsch, Wolfgang

    2016-03-01

    Off-resonance Faraday rotation can offer a new method to monitor the nuclear spin polarization of a dense 3He target and gain access to new information about the magnetic polarizability of the 3He nucleus. The interaction of the polarization state of light with the nuclear spin of the helium atom is very weak and has never been detected. A sensitive triple modulation technique has been developed which can detect the expected rotation angle on the order of 100 nrad. Once a Faraday rotation signal is observed, the next step is to separate the magnetic and electric contributions to the rotation by utilizing their different frequency dependencies. Recent studies involved optimizing several parameters which impact 3He target polarization. Progress towards detecting nuclear spin optical rotation on 3He will be reported. This research is supported by DOE Grant DE-FG02-99ER41101.

  17. Progress Towards the Detection of Faraday Rotation on Spin Polarized 3He

    NASA Astrophysics Data System (ADS)

    Abney, Joshua; Broering, Mark; Korsch, Wolfgang

    2016-05-01

    Off-resonance Faraday rotation can offer a method to measure the nuclear spin optical rotation of the 3 He nucleus and gain access to new information about the atomic polarizability of the Helium atom. The interaction of the polarization state of light with the nuclear spin of the helium atom is very weak and has never been detected. A sensitive triple modulation technique has been developed which can detect the expected rotation angle on the order of 100 nrad. Once a Faraday rotation signal is observed, the next step is to separate the magnetic and electric contributions to the rotation by utilizing their different frequency dependencies. Recent studies involved optimizing several parameters which impact 3 He target polarization. Progress towards detecting nuclear spin optical rotation on 3 He will be reported. This research is supported by DOE Grant DE-FG02-99ER41101.

  18. Long-axis rotation: a missing degree of freedom in avian bipedal locomotion.

    PubMed

    Kambic, Robert E; Roberts, Thomas J; Gatesy, Stephen M

    2014-08-01

    Ground-dwelling birds are typically characterized as erect bipeds having hind limbs that operate parasagittally. Consequently, most previous research has emphasized flexion/extension angles and moments as calculated from a lateral perspective. Three-dimensional (3D) motion analyses have documented non-planar limb movements, but the skeletal kinematics underlying changes in foot orientation and transverse position remain unclear. In particular, long-axis rotation of the proximal limb segments is extremely difficult to measure with topical markers. Here, we present six degree of freedom skeletal kinematic data from maneuvering guineafowl acquired by marker-based XROMM (X-ray Reconstruction of Moving Morphology). Translations and rotations of the hips, knees, ankles and pelvis were derived from animated bone models using explicit joint coordinate systems. We distinguished sidesteps, sidestep yaws, crossover yaws, sidestep turns and crossover turns, but birds often performed a sequence of blended partial maneuvers. Long-axis rotation of the femur (up to 38 deg) modulated the foot's transverse position. Long-axis rotation of the tibiotarsus (up to 65 deg) also affected medio-lateral positioning, but primarily served to either re-orient a swing phase foot or yaw the body about a stance phase foot. Tarsometatarsal long-axis rotation was minimal, as was hip, knee and ankle abduction/adduction. Despite having superficially hinge-like joints, birds coordinate substantial long-axis rotations of the hips and knees to execute complex 3D maneuvers while striking a diversity of non-planar poses. PMID:24855675

  19. Polar flagella rotation in Vibrio parahaemolyticus confers resistance to bacteriophage infection.

    PubMed

    Zhang, Hui; Li, Lu; Zhao, Zhe; Peng, Daxin; Zhou, Xiaohui

    2016-01-01

    Bacteriophage has been recognized as a novel approach to treat bacterial infectious diseases. However, phage resistance may reduce the efficacy of phage therapy. Here, we described a mechanism of bacterial resistance to phage infections. In Gram-negative enteric pathogen Vibrio parahaemolyticus, we found that polar flagella can reduce the phage infectivity. Deletion of polar flagella, but not the lateral flagella, can dramatically promote the adsorption of phage to the bacteria and enhances the phage infectivity to V. parahaemolyticus, indicating that polar flagella play an inhibitory role in the phage infection. Notably, it is the rotation, not the physical presence, of polar flagella that inhibits the phage infection of V. parahaemolyticus. Strikingly, phage dramatically reduces the virulence of V. parahaemolyticus only when polar flagella were absent both in vitro and in vivo. These results indicated that polar flagella rotation is a previously unidentified mechanism that confers bacteriophage resistance. PMID:27189325

  20. Polar flagella rotation in Vibrio parahaemolyticus confers resistance to bacteriophage infection

    PubMed Central

    Zhang, Hui; Li, Lu; Zhao, Zhe; Peng, Daxin; Zhou, Xiaohui

    2016-01-01

    Bacteriophage has been recognized as a novel approach to treat bacterial infectious diseases. However, phage resistance may reduce the efficacy of phage therapy. Here, we described a mechanism of bacterial resistance to phage infections. In Gram-negative enteric pathogen Vibrio parahaemolyticus, we found that polar flagella can reduce the phage infectivity. Deletion of polar flagella, but not the lateral flagella, can dramatically promote the adsorption of phage to the bacteria and enhances the phage infectivity to V. parahaemolyticus, indicating that polar flagella play an inhibitory role in the phage infection. Notably, it is the rotation, not the physical presence, of polar flagella that inhibits the phage infection of V. parahaemolyticus. Strikingly, phage dramatically reduces the virulence of V. parahaemolyticus only when polar flagella were absent both in vitro and in vivo. These results indicated that polar flagella rotation is a previously unidentified mechanism that confers bacteriophage resistance. PMID:27189325

  1. Long-Lived Hole Spin/Valley Polarization Probed by Kerr Rotation in Monolayer WSe2.

    PubMed

    Song, Xinlin; Xie, Saien; Kang, Kibum; Park, Jiwoong; Sih, Vanessa

    2016-08-10

    Time-resolved Kerr rotation and photoluminescence measurements are performed on MOCVD-grown monolayer tungsten diselenide (WSe2). We observe a surprisingly long-lived Kerr rotation signal (∼80 ns) at 10 K, which is attributed to spin/valley polarization of the resident holes. This polarization is robust to transverse magnetic field (up to 0.3 T). Wavelength-dependent measurements reveal that only excitation near the free exciton energy generates this long-lived spin/valley polarization. PMID:27466727

  2. Interesting polarization-independent SERS detection performance induced by the rotation symmetry of multiparticle nanostructures.

    PubMed

    Feng, Chao; Zhao, Yan; Jiang, Yijian

    2016-01-29

    In this work, on the basis of finite difference time domain simulations and group theory, by employing regular nanosphere trimers as the main examples, we analyse and discuss the polarization-independent surface enhanced Raman scattering (SERS) phenomenon arising from the rotation symmetry of coined metallic nanomultimers. The results demonstrate why the rotationally symmetrical nanomultimers can show polarization-independent SERS performance. Because of the dramatically hybridized polarization-independent SERS performance over the whole 360° range, rotationally symmetrical coined metal nanomultimers, such as regular trimers, regular triangular tetramers and regular pentamers, are reliable and reproducible SERS substrates, which have the potential for convenient and flexible practical SERS detection without the need for optimally incident polarization outside the laboratory setting. PMID:26655083

  3. Interesting polarization-independent SERS detection performance induced by the rotation symmetry of multiparticle nanostructures

    NASA Astrophysics Data System (ADS)

    Feng, Chao; Zhao, Yan; Jiang, Yijian

    2016-01-01

    In this work, on the basis of finite difference time domain simulations and group theory, by employing regular nanosphere trimers as the main examples, we analyse and discuss the polarization-independent surface enhanced Raman scattering (SERS) phenomenon arising from the rotation symmetry of coined metallic nanomultimers. The results demonstrate why the rotationally symmetrical nanomultimers can show polarization-independent SERS performance. Because of the dramatically hybridized polarization-independent SERS performance over the whole 360° range, rotationally symmetrical coined metal nanomultimers, such as regular trimers, regular triangular tetramers and regular pentamers, are reliable and reproducible SERS substrates, which have the potential for convenient and flexible practical SERS detection without the need for optimally incident polarization outside the laboratory setting.

  4. Self-Calibration of BICEP1 Three-Year Data and Constraints on Astrophysical Polarization Rotation

    NASA Technical Reports Server (NTRS)

    Kaufman, J. P.; Miller, N. J.; Shimon, M.; Barkats, D.; Bischoff, C.; Buder, I.; Keating, B. G.; Kovac, J. M.; Ade, P. A. R.; Aikin, R.; Battle, J. O.; Bierman, E. M.; Bock, J. J.; Chiang, H. C.; Dowell, C. D.; Duband, L.; Filippini, J.; Hivon, E. F.; Holzapfel, W. L.; Hristov, V. V.; Jones, W. C.; Kernasovskiy, S. S.; Kuo, C. L.; Leitch, E. M.; Mason, P. V.

    2014-01-01

    Cosmic microwave background (CMB) polarimeters aspire to measure the faint B-mode signature predicted to arise from inflationary gravitational waves. They also have the potential to constrain cosmic birefringence, rotation of the polarization of the CMB arising from parity-violating physics, which would produce nonzero expectation values for the CMB's temperature to B-mode correlation (TB) and E-mode to B-mode correlation (EB) spectra. However, instrumental systematic effects can also cause these TB and EB correlations to be nonzero. In particular, an overall miscalibration of the polarization orientation of the detectors produces TB and EB spectra which are degenerate with isotropic cosmological birefringence, while also introducing a small but predictable bias on the BB spectrum. We find that BICEP1 three-year spectra, which use our standard calibration of detector polarization angles from a dielectric sheet, are consistent with a polarization rotation of alpha = -2.77deg +/- 0.86deg (statistical) +/- 1.3deg (systematic). We have revised the estimate of systematic error on the polarization rotation angle from the two-year analysis by comparing multiple calibration methods. We also account for the (negligible) impact of measured beam systematic effects. We investigate the polarization rotation for the BICEP1 100 GHz and 150 GHz bands separately to investigate theoretical models that produce frequency-dependent cosmic birefringence. We find no evidence in the data supporting either of these models or Faraday rotation of the CMB polarization by the Milky Way galaxy's magnetic field. If we assume that there is no cosmic birefringence, we can use the TB and EB spectra to calibrate detector polarization orientations, thus reducing bias of the cosmological B-mode spectrum from leaked E-modes due to possible polarization orientation miscalibration. After applying this "self-calibration" process, we find that the upper limit on the tensor-to-scalar ratio decreases

  5. Alignment, rotation, and spinning of single plasmonic nanoparticles and nanowires using polarization dependent optical forces.

    PubMed

    Tong, Lianming; Miljković, Vladimir D; Käll, Mikael

    2010-01-01

    We demonstrate optical alignment and rotation of individual plasmonic nanostructures with lengths from tens of nanometers to several micrometers using a single beam of linearly polarized near-infrared laser light. Silver nanorods and dimers of gold nanoparticles align parallel to the laser polarization because of the high long-axis dipole polarizability. Silver nanowires, in contrast, spontaneously turn perpendicular to the incident polarization and predominantly attach at the wire ends, in agreement with electrodynamics simulations. Wires, rods, and dimers all rotate if the incident polarization is turned. In the case of nanowires, we demonstrate spinning at an angular frequency of approximately 1 Hz due to transfer of spin angular momentum from circularly polarized light. PMID:20030391

  6. Birefringence and polarization rotator induced by electromagnetically induced transparency in rare earth ion-doped crystals

    NASA Astrophysics Data System (ADS)

    Li, Zhixiang; Liu, Jianji; Yu, Ping; Zhang, Guoquan

    2016-05-01

    The birefringence induced by the electromagnetically induced transparency effect in a {Pr}^{3+}:{Y}_2 {SiO}_5 crystal was studied by using a balanced polarimeter technique. The results show that it is possible to control the polarization state of the output probe beam by adjusting the experimental conditions. Particularly, the coherently prepared {Pr}^{3+}:{Y}_2 {SiO}_5 crystal can serve as a polarization rotator for a linearly polarized input probe beam at the two-photon resonant condition. Such coherent control on the polarization of light should be useful for polarization-based classical and quantum information processing such as all-optical switching, polarization preserving light pulse memory and polarization qubits based on rare earth ion-doped solids.

  7. Rotation-Enabled 7-Degree of Freedom Seismometer for Geothermal Resource Development. Phase 1 Final Report

    SciTech Connect

    Pierson, Bob; Laughlin, Darren

    2013-10-29

    Under this Department of Energy (DOE) grant, A-Tech Corporation d.b.a. Applied Technology Associates (ATA), seeks to develop a seven-degree-of-freedom (7-DOF) seismic measurement tool for high-temperature geothermal applications. The Rotational-Enabled 7-DOF Seismometer includes a conventional tri-axial accelerometer, a conventional pressure sensor or hydrophone, and a tri-axial rotational sensor. The rotational sensing capability is novel, based upon ATA's innovative research in rotational sensing technologies. The geothermal industry requires tools for high-precision seismic monitoring of crack formation associated with Enhanced Geothermal System (EGS) stimulation activity. Currently, microseismic monitoring is conducted by deploying many seismic tools at different depth levels along a 'string' within drilled observation wells. Costs per string can be hundreds of thousands of dollars. Processing data from the spatial arrays of linear seismometers allows back-projection of seismic wave states. In contrast, a Rotational-Enabled 7-DOF Seismometer would simultaneously measure p-wave velocity, s-wave velocity, and incident seismic wave direction all from a single point measurement. In addition, the Rotational-Enabled 7-DOF Seismometer will, by its nature, separate p- and s-waves into different data streams, simplifying signal processing and facilitating analysis of seismic source signatures and geological characterization. By adding measurements of three additional degrees-of-freedom at each level and leveraging the information from this new seismic observable, it is likely that an equally accurate picture of subsurface seismic activity could be garnered with fewer levels per hole. The key cost savings would come from better siting of the well due to increased information content and a decrease in the number of confirmation wells drilled, also due to the increase in information per well. Improved seismic tools may also increase knowledge, understanding, and confidence

  8. Rotation of the cosmic microwave background polarization from weak gravitational lensing.

    PubMed

    Dai, Liang

    2014-01-31

    When a cosmic microwave background (CMB) photon travels from the surface of last scatter through spacetime metric perturbations, the polarization vector may rotate about its direction of propagation. This gravitational rotation is distinct from, and occurs in addition to, the lensing deflection of the photon trajectory. This rotation can be sourced by linear vector or tensor metric perturbations and is fully coherent with the curl deflection field. Therefore, lensing corrections to the CMB polarization power spectra as well as the temperature-polarization cross correlations due to nonscalar perturbations are modified. The rotation does not affect lensing by linear scalar perturbations, but needs to be included when calculations go to higher orders. We present complete results for weak lensing of the full-sky CMB power spectra by general linear metric perturbations, taking into account both deflection of the photon trajectory and rotation of the polarization. For the case of lensing by gravitational waves, we show that the B modes induced by the rotation largely cancel those induced by the curl component of deflection. PMID:24580435

  9. Photoelectron spectroscopic studies of polyatomic molecules: Degree of orientation and ionization of rotationally state selected, oriented molecules

    NASA Astrophysics Data System (ADS)

    Chandra, N.; Chakraborty, M.

    1991-11-01

    In this paper we report theoretical studies of angle-resolved photoelectron spectroscopy (ARPES) and of circular dichroism in photoelectron angular distribution (CDAD) for ionization in molecules oriented in a single ‖JKJMJ> rotational eigenstate. These processes have been investigated also as two of the possible alternatives to photodissociation to determine orientational distribution function of rotationally state selected, oriented molecules. Expressions are derived which can be used to calculate ARPES and CDAD for such molecular species from ab initio methods or to analyze these experimentally observed spectra for extracting information about the degree of orientation of the molecular framework. These formulas are put in their simplest possible forms using the transformation properties of the molecular point group to their full advantage. The ionization amplitude is thus shown to decompose into a sum of transitions each involving the final state wave function belonging to an irreducible representation of the point group of the target molecule. It is found that, similar to the case of photodissociation, one can determine the rotational quantum number J purely from experimental photoionization data. Expressions developed herein are used to study ARPES and CDAD for ionization in a1 orbital of those rotationally state selected and oriented spherical top molecules which transform according to the Td point symmetry group. In this case, the detection-integrated cross section, singly differential in molecular orientation, is found to be independent of the photoionization dynamics and directly gives the molecular orientational function. The other ARPES and CDAD formulas are shown to depend upon the dynamics through the integrated partial cross section σ¯, the angularly asymmetry parameter β¯, the phase shift of the continuum waves representing the photoelectron, and the phase of the dipole transition amplitudes. The formulation presented in this paper sets a

  10. Deterministic Polarization Entanglement Purification of W State in Multiple Degrees of Freedom with Hyper-Entanglement

    NASA Astrophysics Data System (ADS)

    Kuang, Hongyan; Guo, Ying

    2015-01-01

    We present two deterministic entanglement purification protocols for distilling W state in polarization entanglement in a one-step fashion. The three parties can obtain a maximally entangled W polarization state with success probability 100 % from the hyper-entangled W state in multiple degrees of freedom (DOFs), and they do not require the quantum system to be entangled in polarization DOF but in spatial DOF. The former protocol is implemented with the passive linear optics, which is feasible with current experiments. The later one is implemented with cross-Kerr-nonlinearities, which can achieve higher efficiency of the entanglement transformation among different DOFs since it does not require the sophisticated single-photon detector. The present protocols are both suitable for polarization entanglement purification of multi-photon-entangled W state in quantum computation network because they need less operations and classical communications in the practical implementation.

  11. Tools for detecting entanglement between different degrees of freedom in quadrature squeezed cylindrically polarized modes

    NASA Astrophysics Data System (ADS)

    Gabriel, C.; Aiello, A.; Berg-Johansen, S.; Marquardt, Ch.; Leuchs, G.

    2012-07-01

    Quadrature squeezed cylindrically polarized modes contain entanglement not only in the polarization and spatial electric field variables but also between these two degrees of freedom [C. Gabriel et al., Phys. Rev. Lett. 106, 060502 (2011)]. In this paper we present tools to generate and detect this entanglement. Experimentally we demonstrate the generation of quadrature squeezing in cylindrically polarized modes by mode transforming a squeezed Gaussian mode. Specifically, -1.2 dB ± 0.1 dB of amplitude squeezing are achieved in the radially and azimuthally polarized mode. Furthermore, theoretically it is shown how the entanglement contained within these modes can be measured and how strong the quantum correlations are, depending on the measurement scheme.

  12. Differential Rotation and Magnetic Polarity Patterns on AB Doradus

    NASA Astrophysics Data System (ADS)

    Donati, J.-F.; Collier Cameron, A.; Hussain, G. A. J.; Semel, M.

    We report new Zeeman-Doppler imaging observations of the rapidly rotating young K0 dwarf AB Doradus, obtained with the Anglo-Australian Telescope in 1996 December. We show simultaneous brightness and magnetic images of the stellar photosphere, reconstructed at three different epochs over the course of a seven-night observing run. Latitude-by-latitude cross-correlation of the resulting images confirms the form and amplitude of the surface differential pattern found in the previous year's observations by Donati & Cameron (1997), with the pole rotating slower than the equator by about one part in 220. We also present dynamic spectra showing the distribution of H alpha-absorbing clouds in the stellar corona at the same epoch.

  13. Demanding response time requirements on coherent receivers due to fast polarization rotations caused by lightning events.

    PubMed

    Krummrich, Peter M; Ronnenberg, David; Schairer, Wolfgang; Wienold, Daniel; Jenau, Frank; Herrmann, Maximilian

    2016-05-30

    Lightning events can cause fast polarization rotations and phase changes in optical transmission fibers due to strong electrical currents and magnetic fields. Whereas these are unlikely to affect legacy transmission systems with direct detection, different mechanisms have to be considered in systems with local oscillator based coherent receivers and digital signal processing. A theoretical analysis reveals that lightning events can result in polarization rotations with speeds as fast as a few hundred kRad/s. We discuss possible mechanisms how such lightning events can affect coherent receivers with digital signal processing. In experimental investigations with a high current pulse generator and transponder prototypes, we observed post FEC errors after polarization rotation events which can be expected from lightning strikes. PMID:27410158

  14. Analysis of the polarization rotation effect in the inversely tapered spot size converter.

    PubMed

    Jia, Lianxi; Zhou, Haifeng; Liow, Tsung-Yang; Song, Junfeng; Huang, Ying; Tu, Xiaoguang; Luo, Xianshu; Li, Chao; Fang, Qing; Yu, Mingbin; Lo, Guoqiang

    2015-10-19

    Inversely tapered spot size converter (SSC) is widely used to connect silicon waveguide with fiber in silicon photonics. However, the tapered structure may cause polarization rotation and further generate interference fluctuation in the transmission spectrum even of a straight waveguide. We analyzed the light propagation in a straight waveguide with SSC at the both ends with coupling matrix and transmission matrix methods. The analysis results matched with the phenomena we observed in the transmission spectrum. Combining the analysis with the measurement results, we calculated the polarization rotation efficiency of the SSC in different samples and analyzed the origin of the polarization rotation effect. Finally, we discussed the influence of the effect to the DP-QPSK signal and proposed several methods to release the impact. PMID:26480439

  15. Rotations of molecular photoelectron angular distributions with intense ultrashort circularly polarized attosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Yuan, Kai-Jun; Chelkowski, Szczepan; Bandrauk, André D.

    2013-04-01

    Molecular photoelectron angular distributions (MPADs) by intense (I0 ⩾ 1014 W/cm2) circularly polarized ultrashort, few cycle (attosecond) ultraviolet laser pulses are presented from numerical solutions of time dependent Schrödinger equations. For the aligned molecular ion H_2^+, the MPADs exhibit rotations with respect to the polarization and molecular symmetry axes which are determined by the symmetry of the initial electronics states. It is also found that the rotation angle of MPADs is insensitive to the pulse intensity. We attribute these effects to the asymmetry between the parallel and perpendicular (to the molecular axis) polarization photoionization. Influence of the molecular alignment and ionizing pulse ellipticity on the rotation of MPADs is also shown to allow control of the nonsymmetric ionization.

  16. Band gap engineering strategy via polarization rotation in perovskite ferroelectrics

    SciTech Connect

    Wang, Fenggong Grinberg, Ilya; Rappe, Andrew M.

    2014-04-14

    We propose a strategy to engineer the band gaps of perovskite oxide ferroelectrics, supported by first principles calculations. We find that the band gaps of perovskites can be substantially reduced by as much as 1.2 eV through local rhombohedral-to-tetragonal structural transition. Furthermore, the strong polarization of the rhombohedral perovskite is largely preserved by its tetragonal counterpart. The B-cation off-center displacements and the resulting enhancement of the antibonding character in the conduction band give rise to the wider band gaps of the rhombohedral perovskites. The correlation between the structure, polarization orientation, and electronic structure lays a good foundation for understanding the physics of more complex perovskite solid solutions and provides a route for the design of photovoltaic perovskite ferroelectrics.

  17. Cross polarization with long delayed contact in rotating solids

    NASA Astrophysics Data System (ADS)

    Ding, Shangwu; McDowell, Charles A.

    1996-06-01

    The cross polarization NMR spectra and cross relaxation rates of polycrystalline hexamethylbenzene and adamantane were obtained by employing a long delay before contact for samples spinning at, and off, the magic angle with respect to the static magnetic field. The results are compared with those obtained by using the conventional cross polarization pulse sequence. The results support the memory effect explanation of origin of the SPEDA spectra in contrast with the assumptions that the high resolution SPEDA spectra arising either, from the nearly isotropic motion of a very small fraction, or a pool of highly thermo-activated molecules, or from special spin pairs within the crystallites which are orientated at the magic angle with respect to the static magnetic field.

  18. Polarization rotation and coupling between silicon waveguide and hybrid plasmonic waveguide

    PubMed Central

    Kim, Sangsik; Qi, Minghao

    2015-01-01

    We present a polarization rotation and coupling scheme that rotates a TE0 mode in a silicon waveguide and simultaneously couples the rotated mode to a hybrid plasmonic (HP0) waveguide mode. Such a polarization rotation can be realized with a partially etched asymmetric hybrid plasmonic waveguide consisting of a silicon strip waveguide, a thin oxide spacer, and a metal cap made from copper, gold, silver or aluminum. Two implementations, one with and one without the tapering of the metal cap are presented, and different taper shapes (linear and exponential) are also analyzed. The devices have large 3 dB conversion bandwidths (over 200 nm at near infrared) and short length (< 5 μm), and achieve a maximum coupling factor of ∼ 78% with a linearly tapered silver metal cap. PMID:25969038

  19. Second-harmonic generation polarization microscopy by rotation of excitation light

    NASA Astrophysics Data System (ADS)

    Fwu, Peter Tramyeon; Chou, Chen-Kuan; Chen, Wei-Liang; Dong, Chen-Yuan

    2007-02-01

    When imaging anisotropic samples with a laser scanning optical microscope, the results are often affected by the polarization of the excitation light source. Quantifying the polarization dependence of biological fibrous material such as muscle and collagen allows us to gain molecular information at length scale below the resolution of optical microscopes. One problem associated with rotating the direction of linearly polarized excitation light for an epi-illuminated laser scanning microscope is due to the reflective properties of the main dichroic mirror. Depending on the direction of the incident polarization, the dichroic mirror can induce different amount of phase retardation, thus altering the desired output polarization. In this work, we theoretically determined the needed combination of wave plates and their angular positions to compensate for the effect of the dichroic mirror, thus achieving any arbitrary linear polarization angle for the excitation incident on sample.

  20. Real-time image difference detection using a polarization rotation spacial light modulator

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin (Inventor); Liu, Hua-Kuang (Inventor)

    1990-01-01

    An image difference detection system is described, of the type wherein two created image representations such as transparencies representing the images to be compared lie coplanar, while light passes through the two transparencies and is formed into coincident images at the image plane for comparison. The two transparencies are formed by portions of a polarization rotation spacial light modulator display such as a multi-pixel liquid crystal display or a magneto optical rotation type. In a system where light passing through the two transparencies is polarized in transverse directions to enable the use of a Wollaston prism to bring the images into coincidence, a liquid crystal display can be used which is devoid of polarizing sheets that would interfere with transverse polarizing of the light passing through the two transparencies.

  1. Real-time image difference detection using a polarization rotation spacial light modulator

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin (Inventor); Liu, Hua-Kuang (Inventor)

    1988-01-01

    An image difference detection system is described, of the type wherein two created image representations such as transparencies representing the images to be compared lie coplanar, while light passes through the two transparencies and is formed into coincident images at the image plane for comparison. The two transparencies are formed by portions of a polarization-rotation spatial light modulator display such as a multi-pixel liquid crystal display or a magnetooptical rotation type display. In a system where light passing through the two transparencies is polarized in transverse directions to enable the use of a Wollaston prism to bring the images into coincidence, a liquid crystal display can be used which is devoid of polarizing sheets that would interfere with transverse polarizing of the light passing through the two transparencies.

  2. Magneto-optical polarization rotation in a ladder-type atomic system for tunable offset locking

    NASA Astrophysics Data System (ADS)

    Parniak, Michał; Leszczyński, Adam; Wasilewski, Wojciech

    2016-04-01

    We demonstrate an easily tunable locking scheme for stabilizing frequency-sum of two lasers on a two-photon ladder transition based on polarization rotation in warm rubidium vapors induced by magnetic field and circularly polarized drive field. Unprecedented tunability of the two-photon offset frequency is due to strong splitting and shifting of magnetic states in external field. In our experimental setup, we achieve two-photon detuning of up to 700 MHz.

  3. Fast passage dynamic nuclear polarization on rotating solids

    NASA Astrophysics Data System (ADS)

    Mentink-Vigier, Frederic; Akbey, Ümit; Hovav, Yonatan; Vega, Shimon; Oschkinat, Hartmut; Feintuch, Akiva

    2012-11-01

    Magic Angle Spinning (MAS) Dynamic Nuclear Polarization (DNP) has proven to be a very powerful way to improve the signal to noise ratio of NMR experiments on solids. The experiments have in general been interpreted considering the Solid-Effect (SE) and Cross-Effect (CE) DNP mechanisms while ignoring the influence of sample spinning. In this paper, we show experimental data of MAS-DNP enhancements of 1H and 13C in proline and SH3 protein in glass forming water/glycerol solvent containing TOTAPOL. We also introduce a theoretical model that aims at explaining how the nuclear polarization is built in MAS-DNP experiments. By using Liouville space based simulations to include relaxation on two simple spin models, {electron-nucleus} and {electron-electron-nucleus}, we explain how the basic MAS-SE-DNP and MAS-CE-DNP processes work. The importance of fast energy passages and short level anti-crossing is emphasized and the differences between static DNP and MAS-DNP is explained. During a single rotor cycle the enhancement in the {electron-electron-nucleus} system arises from MAS-CE-DNP involving at least three kinds of two-level fast passages: an electron-electron dipolar anti-crossing, a single quantum electron MW encounter and an anti-crossing at the CE condition inducing nuclear polarization in- or decrements. Numerical, powder-averaged, simulations were performed in order to check the influence of the experimental parameters on the enhancement efficiencies. In particular we show that the spinning frequency dependence of the theoretical MAS-CE-DNP enhancement compares favorably with the experimental 1H and 13C MAS-DNP enhancements of proline and SH3.

  4. Rotation of the optical polarization angle associated with the 2008 γ-ray flare of blazar W Comae

    SciTech Connect

    Sorcia, Marco; Benítez, Erika; Cabrera, José I.; Hiriart, David; López, José M.; Mújica, Raúl

    2014-10-10

    An R-band photopolarimetric variability analysis of the TeV bright blazar W Comae between 2008 February 28 and 2013 May 17 is presented. The source showed a gradual tendency to decrease its mean flux level with a total change of 3 mJy. A maximum and minimum brightness states in the R band of 14.25 ± 0.04 and 16.52 ± 0.1 mag, respectively, were observed, corresponding to a maximum variation of ΔF = 5.40 mJy. We estimated a minimum variability timescale of Δt = 3.3 days. A maximum polarization degree P = 33.8% ± 1.6%, with a maximum variation of ΔP = 33.2%, was found. One of our main results is the detection of a large rotation of the polarization angle from 78° to 315° (Δθ ∼ 237°) that coincides in time with the γ-ray flare observed in 2008 June. This result indicates that both optical and γ-ray emission regions could be co-spatial. During this flare, a correlation between the R-band flux and polarization degree was found with a correlation coefficient of r {sub F} {sub –} {sub p} = 0.93 ± 0.11. From the Stokes parameters, we infer the existence of two optically thin synchrotron components that contribute to the polarized flux. One of them is stable with a constant polarization degree of 11%. Assuming a shock-in jet model during the 2008 flare, we estimated a maximum Doppler factor δ {sub D} ∼ 27 and a minimum of δ {sub D} ∼ 16; a minimum viewing angle of the jet ∼2.°0; and a magnetic field B ∼ 0.12 G.

  5. Enhancement of optical polarization degree of AlGaN quantum wells by using staggered structure.

    PubMed

    Wang, Weiying; Lu, Huimin; Fu, Lei; He, Chenguang; Wang, Mingxing; Tang, Ning; Xu, Fujun; Yu, Tongjun; Ge, Weikun; Shen, Bo

    2016-08-01

    Staggered AlGaN quantum wells (QWs) are designed to enhance the transverse-electric (TE) polarized optical emission in deep ultraviolet (DUV) light- emitting diodes (LED). The optical polarization properties of the conventional and staggered AlGaN QWs are investigated by a theoretical model based on the k·p method as well as polarized photoluminescence (PL) measurements. Based on an analysis of the valence subbands and momentum matrix elements, it is found that AlGaN QWs with step-function-like Al content in QWs offers much stronger TE polarized emission in comparison to that from conventional AlGaN QWs. Experimental results show that the degree of the PL polarization at room temperature can be enhanced from 20.8% of conventional AlGaN QWs to 40.2% of staggered AlGaN QWs grown by MOCVD, which is in good agreement with the theoretical simulation. It suggests that polarization band engineering via staggered AlGaN QWs can be well applied in high efficiency AlGaN-based DUV LEDs. PMID:27505782

  6. Degree and plane of polarization of multiple scattered light. 2: Earth's atmosphere with aerosols

    NASA Technical Reports Server (NTRS)

    Plass, G. N.; Kattawar, G. W.

    1972-01-01

    The degree of polarization, as well as the direction of the plane of polarization, were calculated by a Monte Carlo method for the reflected and transmitted photons from the earth's atmosphere. The solar photons were observed during multiple collisions with aerosols and the Rayleigh scattering centers in the atmosphere. The aerosol number density, as well as the ratio of aerosol to Rayleigh scattering, varies with height. The proportion of aerosol to Rayleigh scattering was appropriately chosen at each wavelength 0.4 microns and 0.7 microns; ozone absorption was included where appropriate. Three different aerosol number densities were used to study the effects of aerosol variations. Results are given for a solar zenith angle of 81.37 deg and a surface albedo of zero. The polarization of the reflected and transmitted photons was found to be sensitive to the amount of aerosols in the atmosphere at certain angles of observation.

  7. Demonstration of integrated polarization rotator based on an asymmetric silicon waveguide with a trench

    NASA Astrophysics Data System (ADS)

    Kim, Yudeuk; Kim, Dong Wook; Lee, Moon-Hyeok; Lee, Min Hee; Yoo, Dong Eun; Kim, Ki Nam; Jeon, Sang Chul; Kim, Kyong Hon

    2016-09-01

    An integrated polarization rotator is demonstrated experimentally by forming a strip waveguide with an asymmetric trench on a silicon-on-insulator wafer. The trench is located asymmetrically in the strip waveguide. It induces the evolution of an orthogonal polarization mode upon a linearly polarized beam input, and thus causes polarization rotation. The device is fabricated using a conventional complementary metal oxide semiconductor process with a single dry etching step. The fabricated device shows a maximum transverse electric (TE)-to-transverse magnetic (TM) polarization conversion efficiency of 21.3 dB and an insertion loss of ‑0.95 dB at a 1550 nm wavelength with a device length of 67 μm. The device exhibits a polarization conversion efficiency and insertion loss of 21.1 dB and ‑2.12 dB, respectively, for the TM-to-TE polarization conversion. The optimum parameters for the waveguide size and trench size are investigated by performing numerical simulations, and by demonstrating experimental fabrication and measurement.

  8. Detection of polarization in the cosmic microwave background using DASI. Degree Angular Scale Interferometer.

    PubMed

    Kovac, J M; Leitch, E M; Pryke, C; Carlstrom, J E; Halverson, N W; Holzapfel, W L

    The past several years have seen the emergence of a standard cosmological model, in which small temperature differences in the cosmic microwave background (CMB) radiation on angular scales of the order of a degree are understood to arise from acoustic oscillations in the hot plasma of the early Universe, arising from primordial density fluctuations. Within the context of this model, recent measurements of the temperature fluctuations have led to profound conclusions about the origin, evolution and composition of the Universe. Using the measured temperature fluctuations, the theoretical framework predicts the level of polarization of the CMB with essentially no free parameters. Therefore, a measurement of the polarization is a critical test of the theory and thus of the validity of the cosmological parameters derived from the CMB measurements. Here we report the detection of polarization of the CMB with the Degree Angular Scale Interferometer (DASI). The polarization is deteced with high confidence, and its level and spatial distribution are in excellent agreement with the predictions of the standard theory. PMID:12490941

  9. Rotation of the optical polarization plane for the blazar 4C +38.41

    NASA Astrophysics Data System (ADS)

    Panopoulou, G. V.; Maragkakis, G. M.; Xexakis, K.

    2016-08-01

    We report on the ongoing rotation of the optical polarization angle (R-band) seen in the monitored blazar 4C +38.41 (RA=16:35:15.5, DEC=38:08:05, J2000) as recorded within the framework of the RoboPol program.

  10. Fiber laser modelocked by nonlinear polarization rotation in a fiber loop

    NASA Astrophysics Data System (ADS)

    Kuzin, Evgueni A.; Ibarra-Escamilla, Baldeamr; Gomez-Garcia, D. E.; Haus, Joseph W.

    2002-07-01

    We present the experimental demonstration of a new fiber laser configuration based on the nonlinear optical loop mirror with a symmetrical coupler, and highly twisted low- birefringent fiber in the loop. The nonlinear optical loop mirror configuration operates by nonlinear polarization rotation.

  11. The rotation of scissioning nucleus considered trajectory calculations for ternary fission induced by cold polarized neutrons

    NASA Astrophysics Data System (ADS)

    Guseva, I.; Gusev, Yu.

    2009-10-01

    On the base of modified trajectory calculations the shift of angular distribution of α-particles accompanied the reaction 235U(n,f) induced by cold polarized neutrons is evaluated. It was supposed that angular distribution shift is caused by the rotation of nuclear system before scission. The orientation of a rotation motion is determined by the neutron spin polarization along and opposite to the beam direction. For the first time the estimation was done in the frame of trajectory calculations assuming the rotation motion of scissioning nucleus [1]. The result of the calculation is in a good agreement with experimental data of paper [2], where this new phenomenon was named as ROT-effect.

  12. Degree-scale Cosmic Microwave Background Polarization Measurements from Three Years of BICEP1 Data

    NASA Astrophysics Data System (ADS)

    Barkats, D.; Aikin, R.; Bischoff, C.; Buder, I.; Kaufman, J. P.; Keating, B. G.; Kovac, J. M.; Su, M.; Ade, P. A. R.; Battle, J. O.; Bierman, E. M.; Bock, J. J.; Chiang, H. C.; Dowell, C. D.; Duband, L.; Filippini, J.; Hivon, E. F.; Holzapfel, W. L.; Hristov, V. V.; Jones, W. C.; Kuo, C. L.; Leitch, E. M.; Mason, P. V.; Matsumura, T.; Nguyen, H. T.; Ponthieu, N.; Pryke, C.; Richter, S.; Rocha, G.; Sheehy, C.; Kernasovskiy, S. S.; Takahashi, Y. D.; Tolan, J. E.; Yoon, K. W.

    2014-03-01

    BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B-mode polarization of the cosmic microwave background at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (2006-2008). This work extends the two-year result published in Chiang et al., with additional data from the third season and relaxed detector-selection criteria. This analysis also introduces a more comprehensive estimation of band power window functions, improved likelihood estimation methods, and a new technique for deprojecting monopole temperature-to-polarization leakage that reduces this class of systematic uncertainty to a negligible level. We present maps of temperature, E- and B-mode polarization, and their associated angular power spectra. The improvement in the map noise level and polarization spectra error bars are consistent with the 52% increase in integration time relative to Chiang et al. We confirm both self-consistency of the polarization data and consistency with the two-year results. We measure the angular power spectra at 21 <= l <= 335 and find that the EE spectrum is consistent with Lambda cold dark matter cosmology, with the first acoustic peak of the EE spectrum now detected at 15σ. The BB spectrum remains consistent with zero. From B-modes only, we constrain the tensor-to-scalar ratio to r = 0.03^{+0.27}_{-0.23}, or r < 0.70 at 95% confidence level.

  13. Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect

    NASA Astrophysics Data System (ADS)

    Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang

    2014-05-01

    The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.

  14. Circular Polarizations of Gravitational Waves from Core-Collapse Supernovae: A Clear Indication of Rapid Rotation.

    PubMed

    Hayama, Kazuhiro; Kuroda, Takami; Nakamura, Ko; Yamada, Shoichi

    2016-04-15

    We propose to employ the circular polarization of gravitational waves emitted by core-collapse supernovae as an unequivocal indication of rapid rotation deep in their cores just prior to collapse. It has been demonstrated by three dimensional simulations that nonaxisymmetric accretion flows may develop spontaneously via hydrodynamical instabilities in the postbounce cores. It is not surprising, then, that the gravitational waves emitted by such fluid motions are circularly polarized. We show, in this Letter, that a network of the second generation detectors of gravitational waves worldwide may be able to detect such polarizations up to the opposite side of the Galaxy as long as the rotation period of the core is shorter than a few seconds prior to collapse. PMID:27127951

  15. Semiconductor sensor for optically measuring polarization rotation of optical wavefronts using rare earth iron garnets

    DOEpatents

    Duncan, Paul G.

    2002-01-01

    Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.

  16. Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect.

    PubMed

    Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang

    2014-01-01

    The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved. PMID:24784778

  17. Circular Polarizations of Gravitational Waves from Core-Collapse Supernovae: A Clear Indication of Rapid Rotation

    NASA Astrophysics Data System (ADS)

    Hayama, Kazuhiro; Kuroda, Takami; Nakamura, Ko; Yamada, Shoichi

    2016-04-01

    We propose to employ the circular polarization of gravitational waves emitted by core-collapse supernovae as an unequivocal indication of rapid rotation deep in their cores just prior to collapse. It has been demonstrated by three dimensional simulations that nonaxisymmetric accretion flows may develop spontaneously via hydrodynamical instabilities in the postbounce cores. It is not surprising, then, that the gravitational waves emitted by such fluid motions are circularly polarized. We show, in this Letter, that a network of the second generation detectors of gravitational waves worldwide may be able to detect such polarizations up to the opposite side of the Galaxy as long as the rotation period of the core is shorter than a few seconds prior to collapse.

  18. Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect

    PubMed Central

    Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang

    2014-01-01

    The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved. PMID:24784778

  19. Self-calibration of BICEP1 three-year data and constraints on astrophysical polarization rotation

    NASA Astrophysics Data System (ADS)

    Kaufman, J. P.; Miller, N. J.; Shimon, M.; Barkats, D.; Bischoff, C.; Buder, I.; Keating, B. G.; Kovac, J. M.; Ade, P. A. R.; Aikin, R.; Battle, J. O.; Bierman, E. M.; Bock, J. J.; Chiang, H. C.; Dowell, C. D.; Duband, L.; Filippini, J.; Hivon, E. F.; Holzapfel, W. L.; Hristov, V. V.; Jones, W. C.; Kernasovskiy, S. S.; Kuo, C. L.; Leitch, E. M.; Mason, P. V.; Matsumura, T.; Nguyen, H. T.; Ponthieu, N.; Pryke, C.; Richter, S.; Rocha, G.; Sheehy, C.; Su, M.; Takahashi, Y. D.; Tolan, J. E.; Yoon, K. W.

    2014-03-01

    Cosmic microwave background (CMB) polarimeters aspire to measure the faint B-mode signature predicted to arise from inflationary gravitational waves. They also have the potential to constrain cosmic birefringence, rotation of the polarization of the CMB arising from parity-violating physics, which would produce nonzero expectation values for the CMB's temperature to B-mode correlation (TB) and E-mode to B-mode correlation (EB) spectra. However, instrumental systematic effects can also cause these TB and EB correlations to be nonzero. In particular, an overall miscalibration of the polarization orientation of the detectors produces TB and EB spectra which are degenerate with isotropic cosmological birefringence, while also introducing a small but predictable bias on the BB spectrum. We find that Bicep1 three-year spectra, which use our standard calibration of detector polarization angles from a dielectric sheet, are consistent with a polarization rotation of α =-2.77°±0.86°(statistical)±1.3°(systematic). We have revised the estimate of systematic error on the polarization rotation angle from the two-year analysis by comparing multiple calibration methods. We also account for the (negligible) impact of measured beam systematic effects. We investigate the polarization rotation for the Bicep1 100 GHz and 150 GHz bands separately to investigate theoretical models that produce frequency-dependent cosmic birefringence. We find no evidence in the data supporting either of these models or Faraday rotation of the CMB polarization by the Milky Way galaxy's magnetic field. If we assume that there is no cosmic birefringence, we can use the TB and EB spectra to calibrate detector polarization orientations, thus reducing bias of the cosmological B-mode spectrum from leaked E-modes due to possible polarization orientation miscalibration. After applying this "self-calibration" process, we find that the upper limit on the tensor-to-scalar ratio decreases slightly, from r<0

  20. High-Frequency Dynamic Nuclear Polarization in the Nuclear Rotating Frame

    NASA Astrophysics Data System (ADS)

    Farrar, C. T.; Hall, D. A.; Gerfen, G. J.; Rosay, M.; Ardenkjær-Larsen, J.-H.; Griffin, R. G.

    2000-05-01

    A proton dynamic nuclear polarization (DNP) NMR signal enhancement (ɛ) close to thermal equilibrium, ɛ = 0.89, has been obtained at high field (B0 = 5 T, νepr = 139.5 GHz) using 15 mM trityl radical in a 40:60 water/glycerol frozen solution at 11 K. The electron-nuclear polarization transfer is performed in the nuclear rotating frame with microwave irradiation during a nuclear spin-lock pulse. The growth of the signal enhancement is governed by the rotating frame nuclear spin-lattice relaxation time (T1ρ), which is four orders of magnitude shorter than the nuclear spin-lattice relaxation time (T1n). Due to the rapid polarization transfer in the nuclear rotating frame the experiment can be recycled at a rate of 1/T1ρ and is not limited by the much slower lab frame nuclear spin-lattice relaxation rate (1/T1n). The increased repetition rate allowed in the nuclear rotating frame provides an effective enhancement per unit time1/2 of ɛt = 197. The nuclear rotating frame-DNP experiment does not require high microwave power; significant signal enhancements were obtained with a low-power (20 mW) Gunn diode microwave source and no microwave resonant structure. The symmetric trityl radical used as the polarization source is water-soluble and has a narrow EPR linewidth of 10 G at 139.5 GHz making it an ideal polarization source for high-field DNP/NMR studies of biological systems.

  1. Omni-directional and holonomic rolling platform with decoupled rotational and translational degrees of freedom

    DOEpatents

    Pin, Francois G.; Killough, Stephen M.

    1994-01-01

    A wheel assembly includes a support, a cage rotatably mounted on the support and having a longitudinal rotation axis, a first ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis of the cage, and a second ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis or the cage and to the rotation axis of the first ball wheel. A control circuit includes a photodetector signal which indicates ground contact for each ball wheel, and a tachometer which indicates actual drive shaft velocity.

  2. Omni-directional and holonomic rolling platform with decoupled rotational and translational degrees of freedom

    DOEpatents

    Pin, F.G.; Killough, S.M.

    1994-12-20

    A wheel assembly includes a support, a cage rotatably mounted on the support and having a longitudinal rotation axis, a first ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis of the cage, and a second ball wheel rotatably mounted in the cage and having a rotation axis orthogonal to the rotation axis or the cage and to the rotation axis of the first ball wheel. A control circuit includes a photodetector signal which indicates ground contact for each ball wheel, and a tachometer which indicates actual drive shaft velocity. 6 figures.

  3. Design of polarization rotators in TE-TM mode conversion optical isolator with Ce:YIG guiding layer

    NASA Astrophysics Data System (ADS)

    Okada, Yukihiro; Tamura, Daisuke; Kobayashi, Kouya; Yokoi, Hideki

    2015-09-01

    An optical isolator with a (CeY)3Fe5O12 guiding layer employing TE-TM mode conversion was investigated. The optical isolator consisted of a nonreciprocal polarization rotator and a reciprocal polarization rotator. The reciprocal polarization rotator was realized by inserting a polyimide half-wave plate into a groove in the magnetooptic waveguide. Propagation distances required for the nonreciprocal polarization rotator were calculated at a wavelength of 1.55 µm. Diffraction loss due to the insertion of the half-wave plate was also calculated. The reciprocal polarization rotator integrated with a spot-size converter was proposed for suppressing the diffraction loss. By introducing the spot-size converter for an input facet and an output facet of the half-wave plate, a calculated total insertion loss was reduced to 0.22 dB.

  4. Polarized fluorescence photobleaching recovery for measuring rotational diffusion in solutions and membranes.

    PubMed Central

    Velez, M; Axelrod, D

    1988-01-01

    A variation of fluorescence photobleaching recovery (FPR) suitable for measuring the rate of rotational molecular diffusion in solution and cell membranes is presented in theory and experimental practice for epi-illumination microscopy. In this technique, a brief flash of polarized laser light creates an anisotropic distribution of unbleached fluorophores which relaxes by rotational diffusion, leading to a time-dependent postbleach fluorescence. Polarized FPR (PFPR) is applicable to any time scales from seconds to microseconds. However, at fast (microsecond) time scales, a partial recovery independent of molecular orientation tends to obscure rotational effects. The theory here presents a method for overcoming this reversible photobleaching, and includes explicit results for practical geometries, fast wobble of fluorophores, and arbitrary bleaching depth. This variation of a polarized luminescence "pump-and-probe" technique is compared with prior ones and with "pump-only" time-resolved luminescence anisotropy decay methods. The technique is experimentally verified on small latex beads with a variety of diameters, common fluorophore labels, and solvent viscosities. Preliminary measurements on a protein (acetylcholine receptor) in the membrane of nondeoxygenated cells in live culture (rat myotubes) show a difference in rotational diffusion between clustered and nonclustered receptors. In most experiments, signal averaging, high laser power, and automated sample translation must be employed to achieve adequate statistical accuracy. PMID:3382712

  5. Evaluation of polarization rotation in the scattering responses from individual semiconducting oxide nanorods

    PubMed Central

    Choi, Daniel S.; Singh, Manpreet; Zhou, Hebing; Milchak, Marissa; Monahan, Brian; Hahm, Jong-in

    2016-01-01

    We investigate the interaction of visible light with the solid matters of semiconducting oxide nanorods (NRs) of zinc oxide (ZnO), indium tin oxide (ITO), and zinc tin oxide (ZTO) at the single nanomaterial level. We subsequently identify an intriguing, material-dependent phenomenon of optical rotation in the electric field oscillation direction of the scattered light by systematically controlling the wavelength and polarization direction of the incident light, the NR tilt angle, and the analyzer angle. This polarization rotation effect in the scattered light is repeatedly observed from the chemically pure and highly crystalline ZnO NRs, but absent on the chemically doped NR variants of ITO and ZTO under all measurement circumstances. We further elucidate that the phenomenon of polarization rotation detected from single ZnO NRs is affected by the NR tilt angle, while the phenomenon itself occurs irrespective of the wavelength and incident polarization direction of the visible light. Combined with the widespread optical and optoelectronic use of the semiconducting oxide nanomaterials, these efforts may provide much warranted fundamental bases to tailor material-specific, single nanomaterial-driven, optically modulating functionalities which, in turn, can be beneficial for the realization of high-performance integrated photonic circuits and miniaturized bio-optical sensing devices. PMID:27158560

  6. Evaluation of polarization rotation in the scattering responses from individual semiconducting oxide nanorods

    NASA Astrophysics Data System (ADS)

    Choi, Daniel S.; Singh, Manpreet; Zhou, Hebing; Milchak, Marissa; Monahan, Brian; Hahm, Jong-in

    2016-04-01

    We investigate the interaction of visible light with the solid matters of semiconducting oxide nanorods (NRs) of zinc oxide (ZnO), indium tin oxide (ITO), and zinc tin oxide (ZTO) at the single nanomaterial level. We subsequently identify an intriguing, material-dependent phenomenon of optical rotation in the electric field oscillation direction of the scattered light by systematically controlling the wavelength and polarization direction of the incident light, the NR tilt angle, and the analyzer angle. This polarization rotation effect in the scattered light is repeatedly observed from the chemically pure and highly crystalline ZnO NRs, but absent on the chemically doped NR variants of ITO and ZTO under all measurement circumstances. We further elucidate that the phenomenon of polarization rotation detected from single ZnO NRs is affected by the NR tilt angle, while the phenomenon itself occurs irrespective of the wavelength and incident polarization direction of the visible light. Combined with the widespread optical and optoelectronic use of the semiconducting oxide nanomaterials, these efforts may provide much warranted fundamental bases to tailor material-specific, single nanomaterial-driven, optically modulating functionalities which, in turn, can be beneficial for the realization of high-performance integrated photonic circuits and miniaturized bio-optical sensing devices.

  7. Design of 45-degree Linearly Polarized Substrate Integrated Waveguide-fed Slot Array Antennas

    NASA Astrophysics Data System (ADS)

    Zhang, Qingfeng; Lu, Yilong

    2008-11-01

    This paper presents a method of designing substrate integrated waveguide-fed (SIW-fed) slot array antennas. The design theory is based on the circuit model of slot and via as well as the reflection canceling. To prove the feasibility of this method, a 10-element K-band SIW-fed 45-degree linearly polarized slot array antenna with uniform power distribution is designed. By full-wave simulation, the antenna has a good impedance bandwidth of 7.5% and uniform power distribution. Besides, a maximum gain of 15.3dBi is obtained in the broadside and the cross polarization is suppressed below -23.5dB in the boresight. This type of SIW-fed slot array antennas can be a good candidate for microwave and millimeter-wave applications, especially for auto-motive collision-avoidance radar systems.

  8. Degradation in the degree of polarization in human retinal nerve fiber layer

    NASA Astrophysics Data System (ADS)

    Yin, Biwei; Wang, Bingqing; Rylander, Henry G.; Milner, Thomas E.

    2014-01-01

    Using a fiber-based swept-source (SS) polarization-sensitive optical coherence tomography (PS-OCT) system, we investigate the degree of polarization (DOP) of light backscattered from the retinal nerve fiber layer (RNFL) in normal human subjects. Algorithms for processing data were developed to analyze the deviation in phase retardation and intensity of backscattered light in directions parallel and perpendicular to the nerve fiber axis (fast and slow axes of RNFL). Considering superior, inferior, and nasal quadrants, we observe the strongest degradation in the DOP with increasing RNFL depth in the temporal quadrant. Retinal ganglion cell axons in normal human subjects are known to have the smallest diameter in the temporal quadrant, and the greater degradation observed in the DOP suggests that higher polarimetric noise may be associated with neural structure in the temporal RNFL. The association between depth degradation in the DOP and RNFL structural properties may broaden the utility of PS-OCT as a functional imaging technique.

  9. Earth rotation and polar motion from laser ranging to the moon and artificial satellites

    NASA Technical Reports Server (NTRS)

    Aardoom, L.

    1978-01-01

    Earth-based laser ranging to artificial satellites and to the moon is considered as a technique for monitoring the Earth's polar motion and diurnal rotation. The kinematics of Earth rotation as related to laser ranging is outlined. The current status of laser ranging as regards its measuring capabilities is reviewed. The relative merits of artificial satellite and lunar laser ranging are pointed out. It appears that multistation combined artificial satellite and lunar laser ranging is likely to ultimately meet a 0.002 arcseconds in pole position and 0.1 msec in UT1 daily precision requirement.

  10. Polarized Electronic Absorption Spectrum at 300 Degree K and 77 Degree K: A Physical Chemistry Laboratory Experiment.

    ERIC Educational Resources Information Center

    Johnson, L. W.; Wong, K.

    1979-01-01

    This experiment demonstrates the polarization properties of the transition moment, vibronic activity in an excited state, cyrogenic techniques, crystal site splitting, and the use of mixed crystals. (BB)

  11. Deterministic Polarization Entanglement Purification of Cluster State in Multiple Degrees of Freedom

    NASA Astrophysics Data System (ADS)

    Zhao, Zhisheng; Guo, Ying; Shi, Ronghua; Huang, Dazu

    2015-04-01

    We propose a deterministic polarization entanglement purification protocol (EPP) towards four-photon Cluster state, resorting to linear optic technology and multiple degrees of freedom (DOF). All of the participants can jointedly distill the maximally entangled states from the mixed states after transmission through a noisy channel with success probability 100 % in principle. The proposed protocol can be employed for the purification of any other multi-partite maximally entangled states, such as the Greenberger-Horne-Zeilinger (GHZ) state and W state, which is actually an universally feasible entanglement purification scheme towards multi-photon entanglement system.

  12. Degree-scale cosmic microwave background polarization measurements from three years of BICEP1 data

    SciTech Connect

    Barkats, D.; Aikin, R.; Bock, J. J.; Filippini, J.; Hristov, V. V.; Bischoff, C.; Buder, I.; Kovac, J. M.; Kaufman, J. P.; Keating, B. G.; Bierman, E. M.; Su, M.; Ade, P. A. R.; Battle, J. O.; Dowell, C. D.; Chiang, H. C.; Duband, L.; Hivon, E. F.; Holzapfel, W. L.; Jones, W. C.; and others

    2014-03-10

    BICEP1 is a millimeter-wavelength telescope designed specifically to measure the inflationary B-mode polarization of the cosmic microwave background at degree angular scales. We present results from an analysis of the data acquired during three seasons of observations at the South Pole (2006-2008). This work extends the two-year result published in Chiang et al., with additional data from the third season and relaxed detector-selection criteria. This analysis also introduces a more comprehensive estimation of band power window functions, improved likelihood estimation methods, and a new technique for deprojecting monopole temperature-to-polarization leakage that reduces this class of systematic uncertainty to a negligible level. We present maps of temperature, E- and B-mode polarization, and their associated angular power spectra. The improvement in the map noise level and polarization spectra error bars are consistent with the 52% increase in integration time relative to Chiang et al. We confirm both self-consistency of the polarization data and consistency with the two-year results. We measure the angular power spectra at 21 ≤ ℓ ≤ 335 and find that the EE spectrum is consistent with Lambda cold dark matter cosmology, with the first acoustic peak of the EE spectrum now detected at 15σ. The BB spectrum remains consistent with zero. From B-modes only, we constrain the tensor-to-scalar ratio to r=0.03{sub −0.23}{sup +0.27}, or r < 0.70 at 95% confidence level.

  13. Algal fluorescence: impact and potential for retrieval from measurements of the underwater degree of polarization

    NASA Astrophysics Data System (ADS)

    Ahmed, S.; Tonizzo, A.; Ibrahim, A.; Gilerson, A.; Gross, B.; Moshary, F.

    2012-09-01

    Algorithms for retrieving inherent optical properties (IOPs) in coastal waters from remote sensing of water leaving reflectance spectra, are increasingly focused on red and near infrared (NIR) spectral bands, since the simple blue - green ratio approaches, valid in open oceans, fail when in coastal waters with strongly scattering inorganic particles and colored dissolved organic matter (CDOM). NIR spectra can however be significantly impacted by overlapping chlorophyll a fluorescence, and considerable progress has been made to quantify its contribution, and hence achieve more accurate [Chl] retrievals. Recently we have been studying multiangular hyperspectral polarization characteristics of underwater scattered light, using our recently developed Stokes vector polarimeter to fully measure Stokes parameters. From these studies, information on IOPs, in particular the characteristics of non - algal particles (NAP), which are the primary source of underwater polarized elastic scattering, can be obtained. Multiangular hyperspectral polarization measurements, combined with those of IOPs collected in eutrophic waters of Chesapeake/Virginia and New York Harbor/Hudson River areas, showed that chlorophyll a fluorescence markedly impacts (reduces) the underwater degree of polarization (DOP) in the 650 - 700 nm spectral region. By noting the unpolarized nature of algal fluorescence and the partially polarized properties of elastic scattering, we are able to separate the chlorophyll a fluorescence signal from the total reflectance. The analysis is based on comparisons of experimental measurements with vector/scalar radiative transfer computations using measured IOPs as inputs. Relationships between change in observed DOP and fluorescence contributions are examined, and the possibility of using DOP measurements for underwater fluorescence retrieval is evaluated for different scattering geometries.

  14. Polarization Rotation and Circular Dichroism Near the Potassium D2 Lines

    NASA Astrophysics Data System (ADS)

    Conover, Charles; Thiha, Htet; Dahnke, Jennifer

    2010-03-01

    We have experimentally measured the Faraday rotation and the differential absorption of the two circular polarizations for light tuned near the D2 line in potassium (766.7 nm). In particular we have explored the vapor temperature and magnetic field dependence of the frequency of the zero crossings of the lineshapes from the circular analyzer and the balanced polarimeter used in the measurements. These signals are routinely used as frequency references for laser locking and we discuss the sensitivity to experimental parameters.

  15. The dynamics of plus end polarization and microtubule assembly during Xenopus cortical rotation.

    PubMed

    Olson, David J; Oh, Denise; Houston, Douglas W

    2015-05-15

    The self-organization of dorsally-directed microtubules during cortical rotation in the Xenopus egg is essential for dorsal axis formation. The mechanisms controlling this process have been problematic to analyze, owing to difficulties in visualizing microtubules in living egg. Also, the order of events occurring at the onset of cortical rotation have not been satisfactorily visualized in vivo and have been inferred from staged fixed samples. To address these issues, we have characterized the dynamics of total microtubule and plus end behavior continuously throughout cortical rotation, as well as in oocytes and unfertilized eggs. Here, we show that the nascent microtubule network forms in the cortex but associates with the deep cytoplasm at the start of rotation. Importantly, plus ends remain cortical and become increasingly more numerous and active prior to rotation, with dorsal polarization occurring rapidly after the onset of rotation. Additionally, we show that vegetally localized Trim36 is required to attenuate dynamic plus end growth, suggesting that vegetal factors are needed to locally coordinate growth in the cortex. PMID:25753733

  16. Rotation measure synthesis study and polarized properties of PSR J1745-2900 at 7 mm

    NASA Astrophysics Data System (ADS)

    Kravchenko, E. V.; Cotton, W. D.; Yusef-Zadeh, F.; Kovalev, Y. Y.

    2016-06-01

    We present results of interferometric polarization observations of the recently discovered magnetar J1745-2900 in the vicinity of the Galactic Centre. The observations were made with the Karl G. Jansky Very Large Array (VLA) on 2014 February 21 in the range 40-48 GHz. The full polarization mode and A configuration of the array were used. The average total and linearly polarized flux density of the pulsar amounts to 2.3 ± 0.31 and 1.5 ± 0.2 mJy beam-1, respectively. Analysis shows a rotation measure (RM) of (-67 ± 3) × 103 rad m-2, which is in good agreement with previous measurements at longer wavelengths. These high-frequency observations are sensitive to RM values of up to ˜2 × 107 rad m-2. However, application of the Faraday RM synthesis technique did not reveal other significant RM components in the pulsar emission. This supports an external nature of a single thin Faraday-rotating screen which should be located close to the Galactic Centre. The Faraday-corrected intrinsic electric vector position angle is 16 ± 9 deg east of north, and coincides with the position angle of the pulsar's transverse velocity. All measurements of the pulsar's RM value to date, including the one presented here, well agree within errors, which points towards a steady nature of the Faraday-rotating medium.

  17. Digital Beam Steering Device Based on Decoupled Birefringent Prism Deflector and Polarization Rotator

    NASA Technical Reports Server (NTRS)

    Pishnyak, Oleg; Kreminska, Lyubov; Laventovich, Oleg D.; Pouch, John J.; Miranda, Felix A.; Winker, Bruce K.

    2004-01-01

    We describe digital beam deflectors (DBDs) based on liquid crystals. Each stage of the device comprises a polarization rotator and a birefringent prism deflector. The birefringent prism deflects the beam by an angle that depends on polarization of the incident beam. The prism can be made of the uniaxial smectic A (SmA) liquid crystal (LC) or a solid crystal such as yttrium orthovanadate (YVO4). SmA prisms have high birefringence and can be constructed in a variety of shapes, including single prisms and prismatic blazed gratings of different angles and profiles. We address the challenges of uniform alignment of SmA, such as elimination of focal conic domains. Rotation of linear polarization is achieved by an electrically switched twisted nematic (TN) cell. A DBD composed of N rotator-deflector pairs steers the beam into 2(sup N) directions. As an example, we describe a four-stage DBD deflecting normally incident laser beam within the range of +/- 56 mrad with 8 mrad steps. Redirection of the beam is achieved by switching the TN cells.

  18. Polarization rotator of arbitrary angle based on simple slot-array

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Cao, Xiaohang; Yu, Junsheng; Chen, Xiaodong; Yao, Yuan; Qi, Limei; Chen, Zhijiao; Zhou, Jun

    2015-12-01

    A novel polarization rotator of arbitrary angle was proposed and realized based on simple slot arrays. To achieve the rotation of an arbitrary angle α, the slots on the first layer have to be at an angle of α to the slots on the second layer. Consequently, 90° rotation can be realized using two perpendicularly oriented slot arrays, which overturns the conventional notion of that perpendicular slot arrays are not possible to pass electromagnetic wave. In addition, such structure provides the same bandwidth comparing to its counterpart utilized for frequency selective surface (FSS). Furthermore, such structure is much easier to be fabricated compared to the substrate integrated waveguide (SIW) array. Moreover, low insertion loss can be achieved based on metallic material.

  19. Renormalized vacuum polarization on rotating warped AdS3 black holes

    NASA Astrophysics Data System (ADS)

    Ferreira, Hugo R. C.; Louko, Jorma

    2015-01-01

    We compute the renormalized vacuum polarization of a massive scalar field in the Hartle-Hawking state on (2 +1 )-dimensional rotating, spacelike stretched black hole solutions to topologically massive gravity, surrounded by a Dirichlet mirror that makes the state well defined. The Feynman propagator is written as a mode sum on the complex Riemannian section of the spacetime, and a Hadamard renormalization procedure is implemented by matching to a mode sum on the complex Riemannian section of a rotating Minkowski spacetime. No analytic continuation in the angular momentum parameter is invoked. Selected numerical results are given, demonstrating the numerical efficacy of the method. We anticipate that this method can be extended to wider classes of rotating black hole spacetimes, in particular to the Kerr spacetime in four dimensions.

  20. VCSEL-powered and polarization-maintaining fiber-optic grating vector rotation sensor.

    PubMed

    Guo, Tuan; Liu, Fu; Du, Fa; Zhang, Zhaochuan; Li, Chunjie; Guan, Bai-Ou; Albert, Jacques

    2013-08-12

    A compact fiber-optic vector rotation sensor in which a short section of polarization-maintaining (PM) fiber stub containing a straight fiber Bragg grating (FBG) is spliced to another single mode fiber without any lateral offset is proposed and experimentally demonstrated. Due to the intrinsic birefringence of the PM fiber, two well-defined resonances (i.e. orthogonally polarized FBG core modes) with wavelength separation of 0.5 nm have been achieved in reflection, and they exhibit a high sensitivity to fiber rotation. Both the orientation and the angle of rotation can be determined unambiguously via simple power detection of the relative amplitudes of the orthogonal core reflections. Meanwhile, instead of using a broadband source (BBS), the sensor is powered by a commercial vertical cavity surface emitting laser (VCSEL) with the laser wavelength matched to the PM-FBG core modes, which enables the sensor to work at much higher power levels (~15 dB better than BBS). This improves the signal-to-noise ratio considerably (~50 dB), and makes a demodulation filter unnecessary. Vector rotation measurement with a sensitivity of 0.09 dB/deg has been achieved via cost-effective single detector real time power measurement, and the unwanted power fluctuations and temperature perturbations can be effectively referenced out. PMID:23938824

  1. Rotating-frame perspective on high-order-harmonic generation of circularly polarized light

    NASA Astrophysics Data System (ADS)

    Reich, Daniel M.; Madsen, Lars Bojer

    2016-04-01

    We employ a rotating frame of reference to elucidate high-order-harmonic generation of circularly polarized light by bicircular driving fields. In particular, we show how the experimentally observed circular components of the high-order-harmonic spectrum can be directly related to the corresponding quantities in the rotating frame. Supported by numerical simulations of the time-dependent Schrödinger equation, we deduce an optimal strategy for maximizing the cutoff in the high-order-harmonic plateau while keeping the two circular components of the emitted light spectrally distinct. Moreover, we show how the rotating-frame picture can be more generally employed for elliptical drivers. Finally, we point out how circular and elliptical driving fields show a near-duality to static electric and magnetic fields in a rotating-frame description. This demonstrates how high-order-harmonic generation of circularly polarized light under static electromagnetic fields can be emulated in practice even at static field strengths beyond current experimental capabilities.

  2. SCIENTIFIC VERIFICATION OF FARADAY ROTATION MODULATORS: DETECTION OF DIFFUSE POLARIZED GALACTIC EMISSION

    SciTech Connect

    Moyerman, S.; Bierman, E.; Kaufman, J.; Keating, B. G.; Ade, P. A. R.; Aiken, R.; Hristov, V. V.; Jones, W. C.; Mason, P. V.; Barkats, D.; Bischoff, C.; Kovac, J. M.; Bock, J. J.; Dowell, C. D.; Chiang, H. C.; Duband, L.; Hivon, E. F.; Holzapfel, W. L.; Kuo, C. L.; Leitch, E. M.; and others

    2013-03-01

    The design and performance of a wide bandwidth linear polarization modulator based on the Faraday effect is described. Faraday Rotation Modulators (FRMs) are solid-state polarization switches that are capable of modulation up to 10 kHz. Six FRMs were utilized during the 2006 observing season in the Background Imaging of Cosmic Extragalactic Polarization (BICEP) experiment; three FRMs were used at each of BICEP's 100 and 150 GHz frequency bands. The technology was verified through high signal-to-noise detection of Galactic polarization using two of the six FRMs during four observing runs in 2006. The features exhibit strong agreement with BICEP's measurements of the Galaxy using non-FRM pixels and with the Galactic polarization models. This marks the first detection of high signal-to-noise mm-wave celestial polarization using fast, active optical modulation. The performance of the FRMs during periods when they were not modulated was also analyzed and compared to results from BICEP's 43 pixels without FRMs.

  3. Error motion compensating tracking interferometer for the position measurement of objects with rotational degree of freedom

    NASA Astrophysics Data System (ADS)

    Holler, Mirko; Raabe, Jörg

    2015-05-01

    The nonaxial interferometric position measurement of rotating objects can be performed by imaging the laser beam of the interferometer to a rotating mirror which can be a sphere or a cylinder. This, however, requires such rotating mirrors to be centered on the axis of rotation as a wobble would result in loss of the interference signal. We present a tracking-type interferometer that performs such measurement in a general case where the rotating mirror may wobble on the axis of rotation, or even where the axis of rotation may be translating in space. Aside from tracking, meaning to measure and follow the position of the rotating mirror, the interferometric measurement errors induced by the tracking motion of the interferometer itself are optically compensated, preserving nanometric measurement accuracy. As an example, we show the application of this interferometer in a scanning x-ray tomography instrument.

  4. Rotatable spin-polarized electron source for inverse-photoemission experiments

    SciTech Connect

    Stolwijk, S. D. Wortelen, H.; Schmidt, A. B.; Donath, M.

    2014-01-15

    We present a ROtatable Spin-polarized Electron source (ROSE) for the use in spin- and angle-resolved inverse-photoemission (SR-IPE) experiments. A key feature of the ROSE is a variable direction of the transversal electron beam polarization. As a result, the inverse-photoemission experiment becomes sensitive to two orthogonal in-plane polarization directions, and, for nonnormal electron incidence, to the out-of-plane polarization component. We characterize the ROSE and test its performance on the basis of SR-IPE experiments. Measurements on magnetized Ni films on W(110) serve as a reference to demonstrate the variable spin sensitivity. Moreover, investigations of the unoccupied spin-dependent surface electronic structure of Tl/Si(111) highlight the capability to analyze complex phenomena like spin rotations in momentum space. Essentially, the ROSE opens the way to further studies on complex spin-dependent effects in the field of surface magnetism and spin-orbit interaction at surfaces.

  5. ROTATIONAL VARIABILITY OF EARTH'S POLAR REGIONS: IMPLICATIONS FOR DETECTING SNOWBALL PLANETS

    SciTech Connect

    Cowan, Nicolas B.; Robinson, Tyler; Agol, Eric; Meadows, Victoria S.; Shields, Aomawa L.; Livengood, Timothy A.; Deming, Drake; A'Hearn, Michael F.; Wellnitz, Dennis D.; Charbonneau, David; Lisse, Carey M.

    2011-04-10

    We have obtained the first time-resolved, disk-integrated observations of Earth's poles with the Deep Impact spacecraft as part of the EPOXI mission of opportunity. These data mimic what we will see when we point next-generation space telescopes at nearby exoplanets. We use principal component analysis (PCA) and rotational light curve inversion to characterize color inhomogeneities and map their spatial distribution from these unusual vantage points, as a complement to the equatorial views presented by Cowan et al. in 2009. We also perform the same PCA on a suite of simulated rotational multi-band light curves from NASA's Virtual Planetary Laboratory three-dimensional spectral Earth model. This numerical experiment allows us to understand what sorts of surface features PCA can robustly identify. We find that the EPOXI polar observations have similar broadband colors as the equatorial Earth, but with 20%-30% greater apparent albedo. This is because the polar observations are most sensitive to mid-latitudes, which tend to be more cloudy than the equatorial latitudes emphasized by the original EPOXI Earth observations. The cloudiness of the mid-latitudes also manifests itself in the form of increased variability at short wavelengths in the polar observations and as a dominant gray eigencolor in the south polar observation. We construct a simple reflectance model for a snowball Earth. By construction, our model has a higher Bond albedo than the modern Earth; its surface albedo is so high that Rayleigh scattering does not noticeably affect its spectrum. The rotational color variations occur at short wavelengths due to the large contrast between glacier ice and bare land in those wavebands. Thus, we find that both the broadband colors and diurnal color variations of such a planet would be easily distinguishable from the modern-day Earth, regardless of viewing angle.

  6. Rotational Variability of Earth's Polar Regions: Implications for Detecting Snowball Planets

    NASA Astrophysics Data System (ADS)

    Cowan, Nicolas B.; Robinson, Tyler; Livengood, Timothy A.; Deming, Drake; Agol, Eric; A'Hearn, Michael F.; Charbonneau, David; Lisse, Carey M.; Meadows, Victoria S.; Seager, Sara; Shields, Aomawa L.; Wellnitz, Dennis D.

    2011-04-01

    We have obtained the first time-resolved, disk-integrated observations of Earth's poles with the Deep Impact spacecraft as part of the EPOXI mission of opportunity. These data mimic what we will see when we point next-generation space telescopes at nearby exoplanets. We use principal component analysis (PCA) and rotational light curve inversion to characterize color inhomogeneities and map their spatial distribution from these unusual vantage points, as a complement to the equatorial views presented by Cowan et al. in 2009. We also perform the same PCA on a suite of simulated rotational multi-band light curves from NASA's Virtual Planetary Laboratory three-dimensional spectral Earth model. This numerical experiment allows us to understand what sorts of surface features PCA can robustly identify. We find that the EPOXI polar observations have similar broadband colors as the equatorial Earth, but with 20%-30% greater apparent albedo. This is because the polar observations are most sensitive to mid-latitudes, which tend to be more cloudy than the equatorial latitudes emphasized by the original EPOXI Earth observations. The cloudiness of the mid-latitudes also manifests itself in the form of increased variability at short wavelengths in the polar observations and as a dominant gray eigencolor in the south polar observation. We construct a simple reflectance model for a snowball Earth. By construction, our model has a higher Bond albedo than the modern Earth; its surface albedo is so high that Rayleigh scattering does not noticeably affect its spectrum. The rotational color variations occur at short wavelengths due to the large contrast between glacier ice and bare land in those wavebands. Thus, we find that both the broadband colors and diurnal color variations of such a planet would be easily distinguishable from the modern-day Earth, regardless of viewing angle.

  7. Polarization rotator based on augmented low-index-guiding waveguide on silicon nitride/silicon-on-insulator platform.

    PubMed

    Sun, X; Alam, M Z; Aitchison, J S; Mojahedi, M

    2016-07-15

    Using a newly proposed augmented low-index-guiding scheme with silicon nitride/silicon dual-core waveguide, we have designed, fabricated, and characterized a transverse electric (TE) to transverse magnetic (TM) and TM-to-TE compact polarization rotator. The polarization rotation is realized in an asymmetric directional coupler. The measured peak conversion efficiencies for the TE-to-TM and TM-to-TE rotations are approximately 97%. The measured polarization extinction ratio for the TE-to-TM rotation is greater than 20 dB over 50-nm bandwidth, while for the TM-to-TE rotation it is greater than 15 dB over the C-band. PMID:27420502

  8. New kind of polarotaxis governed by degree of polarization: attraction of tabanid flies to differently polarizing host animals and water surfaces

    NASA Astrophysics Data System (ADS)

    Egri, Ádám; Blahó, Miklós; Sándor, András; Kriska, György; Gyurkovszky, Mónika; Farkas, Róbert; Horváth, Gábor

    2012-05-01

    Aquatic insects find their habitat from a remote distance by means of horizontal polarization of light reflected from the water surface. This kind of positive polarotaxis is governed by the horizontal direction of polarization (E-vector). Tabanid flies also detect water by this kind of polarotaxis. The host choice of blood-sucking female tabanids is partly governed by the linear polarization of light reflected from the host's coat. Since the coat-reflected light is not always horizontally polarized, host finding by female tabanids may be different from the established horizontal E-vector polarotaxis. To reveal the optical cue of the former polarotaxis, we performed choice experiments in the field with tabanid flies using aerial and ground-based visual targets with different degrees and directions of polarization. We observed a new kind of polarotaxis being governed by the degree of polarization rather than the E-vector direction of reflected light. We show here that female and male tabanids use polarotaxis governed by the horizontal E-vector to find water, while polarotaxis based on the degree of polarization serves host finding by female tabanids. As a practical by-product of our studies, we explain the enigmatic attractiveness of shiny black spheres used in canopy traps to catch tabanids.

  9. New kind of polarotaxis governed by degree of polarization: attraction of tabanid flies to differently polarizing host animals and water surfaces.

    PubMed

    Egri, Ádám; Blahó, Miklós; Sándor, András; Kriska, György; Gyurkovszky, Mónika; Farkas, Róbert; Horváth, Gábor

    2012-05-01

    Aquatic insects find their habitat from a remote distance by means of horizontal polarization of light reflected from the water surface. This kind of positive polarotaxis is governed by the horizontal direction of polarization (E-vector). Tabanid flies also detect water by this kind of polarotaxis. The host choice of blood-sucking female tabanids is partly governed by the linear polarization of light reflected from the host's coat. Since the coat-reflected light is not always horizontally polarized, host finding by female tabanids may be different from the established horizontal E-vector polarotaxis. To reveal the optical cue of the former polarotaxis, we performed choice experiments in the field with tabanid flies using aerial and ground-based visual targets with different degrees and directions of polarization. We observed a new kind of polarotaxis being governed by the degree of polarization rather than the E-vector direction of reflected light. We show here that female and male tabanids use polarotaxis governed by the horizontal E-vector to find water, while polarotaxis based on the degree of polarization serves host finding by female tabanids. As a practical by-product of our studies, we explain the enigmatic attractiveness of shiny black spheres used in canopy traps to catch tabanids. PMID:22580753

  10. Mode-evolution-based polarization rotator-splitter design via simple fabrication process.

    PubMed

    Yuan, Wangqing; Kojima, Keisuke; Wang, Bingnan; Koike-Akino, Toshiaki; Parsons, Kieran; Nishikawa, Satoshi; Yagyu, Eiji

    2012-04-23

    A mode-evolution-based polarization rotator-splitter built on InP substrate is proposed by combining a mode converter and an adiabatic asymmetric Y-coupler. The mode converter, consisting of a bi-level taper and a width taper, effectively converts the fundamental TM mode into the second order TE mode without changing the polarization of the fundamental TE mode. The following adiabatic asymmetric Y-coupler splits the fundamental and the second order TE modes and also converts the second order TE mode into the fundamental TE mode. A shallow etched structure is proposed for the width taper to enhance the polarization conversion efficiency. The device has a total length of 1350 µm, a polarization extinction ratio over 25 dB and an insertion loss below 0.5 dB both for TE and TM modes, over the wavelength range from 1528 to 1612 nm covering all C + L band. Because the device is designed based on mode evolution principle, it has a large fabrication tolerance. The insertion loss remains below 1 dB and the polarization extinction ratio remains over 17 dB with respect to a width variation of +/- 0.12 µm at the wavelength of 1570 nm, or +/- 0.08 µm over the entire C + L band. PMID:22535107

  11. Stable multi-wavelength fiber laser based on a compounded nonlinear polarization rotation effect

    NASA Astrophysics Data System (ADS)

    Zou, Hui; Lou, Shuqin; Ma, Jianli; Su, Wei; Han, Bolin; Shen, Xiao

    2014-11-01

    A stable multi-wavelength polarization-maintaining erbium-doped fiber (PM-EDF) laser with high signal-to-noise ratio (SNR) based on a compounded nonlinear polarization rotation effect (CNPRE) is proposed and demonstrated. In order to effectively reduce homogeneous broadening of EDF and then to the alleviate mode competition, two sandwich configurations formed by a polarization dependent isolator (PDI) or a segment of single-mode fiber sandwiched between two polarization controllers (PC), are introduced into the ring cavity to generate the CNPRE. A home-made asymmetry twin-core fiber (ATCF) is also incorporated in the ring cavity as a comb filter. With only 150 mW pump power, there are up to 45-wavelengths lasing with the approximate amplitude in a 3 dB bandwidth generated at room temperature. The wavelength spacing between the adjacent peaks is 0.29 nm and the highest SNRs reach 41.5 dB by optimizing the state of polarization of PCs. The power fluctuation and wavelength shift for each lasing wavelength are less than 0.05 dB and 0.02 nm, respectively. This indicates that the proposed multi-wavelength fiber laser can be stably operated at room temperature.

  12. Angular momentum transfer and polarization degree of ions with one-valence electron by electron impact

    NASA Astrophysics Data System (ADS)

    Akita, Kenichi; Kai, Takeshi; Nakazaki, Shinobu; Igarashi, Akinori

    2009-04-01

    We carry out the R-matrix calculations for electron-impact excitations of ions with one valence electron. The integral cross sections and polarization degree are obtained for the excitation process from the ground state to the first 2P° state of Li2+, B2+ and Al2+ as functions of electron incident energy. The differential cross sections and angular momentum transfer are also shown at non-resonant low-energy points. As for the angular momentum transfer (L⊥) at small scattering angles, they are negative for B2+ and Al2+, while it is positive for Li2+. Thus L⊥ of doubly charged ions with one-valence electron is not simple.

  13. Where are the BTZ black hole degrees of freedom? The rotating case

    NASA Astrophysics Data System (ADS)

    Mitchell, Joseph M.

    2016-07-01

    Recent work has shown that the entropy of the non-rotating BTZ black hole can be derived from a dual conformal description at any spatial location. In this followup it is shown that a dual conformal description exists at any spatial location for the rotating BTZ black hole as well. As in the non-rotating case, two copies of the central charge {c}+/- =3{\\ell }/2G are recovered and the microcanonical Cardy formula yields the correct Bekenstein–Hawking entropy.

  14. In-line polarization rotator based on the quantum-optical analogy.

    PubMed

    Chen, Lei; Qu, Ke-Nan; Shen, Heng; Zhang, Wei-Gang; Chou, Keng C; Liu, Qian; Yan, Tie-Yi; Wang, Biao; Wang, Song

    2016-05-01

    An in-line polarization rotator (PR) is proposed based on the quantum-optical analogy (QOA). The proposed PR possesses an auxiliary E7 liquid crystal (LC) waveguide in the vicinity of the single-mode fiber (SMF) core. Because of the matched core size, the PR demonstrates good compatibility with the established backbone networks which are composed of conventional SMFs. With optimized parameters for the auxiliary waveguide, the PR offers a near 100% polarization conversion efficiency at the 1550 nm band with a bandwidth of ∼30  nm, a length of ∼4625.9  μm with a large tolerance of ∼550  μm, and a tolerance of the input light polarization angle and rotation angle of the E7 LC of ∼π/30 and ∼π/36  rad, respectively. The performance was verified by the full-vector finite-element method. The proposed PR can be easily fabricated based on the existing photonics crystal fiber manufacturing process, making it a potentially inexpensive device for applications in modern communication systems. Moreover, the QOA, compared with the previous supermode-theory design method, allows a designer to consider several waveguides separately. Therefore, various unique characteristics can be met simultaneously which is consistent with the trend of modern fiber design. PMID:27128087

  15. Realization of Hadamard, Pauli-X and rotation gate for polarization-encoded qubits on chip

    NASA Astrophysics Data System (ADS)

    Heilmann, Rene; Graefe, Markus; Nolte, Stefan; Szameit, Alexander

    2014-05-01

    The implementation of quantum operations in photonic devices plays a central role towards quantum computing, as light is a logical choice when low decoherence and stability is of interest. Particular interest is thereby given to polarization-encoded photonic qubits on chip that are superior in terms of stability and size. However, to date waveguide-based modulating polarization states was beyond technological capabilities, preventing from the implementation of universal quantum computing algorithms on chip. In our work we close this gap and present integrated Hadamard, Pauli-X and rotation gates of high fidelity for photonic polarization qubits by employing a reorientation of the birefringent waveguide's optical axis. To this end, we employ laser-written waveguides and use several of their unique features. Due to the impact of an artificial stress field created by an additional defect close to the waveguide, its optical axis is rotated. Further on, by adjusting the length of the defect, the retardation between ordinary and extraordinary field components is precisely tunable including half-wave plate and quarter-wave plate operations. A theoretical treatment as well as characterization of the implemented gates by classical and quantum light are presented.

  16. Triaxial Earth's rotation: Chandler wobble, free core nutation and diurnal polar motion (Abstract)

    NASA Astrophysics Data System (ADS)

    Sun, R.; Shen, W.-B.

    2015-08-01

    In this study, we formulate two-layered triaxial Earth rotation theory, focusing on the influence of the triaxiality on the Chandler wobble (CW), free core nutation (FCN) and diurnal polar motion. We estimate the frequencies of the normal modes CW and FCN, and results show that though the influence of two-layer triaxiality on the CW and FCN frequencies are very small, there appear some new natures. The response of the Earth's polar motion to the excitation consists of two parts. One is in response to the same frequency excitation and the other is in response to the opposite frequency excitation. For an Earth model with triaxial mantle and core, both of these two parts have four resonant frequencies rather than two that are suggested by rotational symmetric Earth model. However, due to the small strength of these new resonances, the effects of these resonances are only significant when the excitation frequencies are very near to these resonance frequencies. In addition, compared to the biaxial case, the influences of the triaxiality on the prograde and retrograde diurnal polar motions excited by ocean tide component K1 are estimated as - 1.4 μas and - 0.9 μas respectively, which should be taken into account in theory. This study is supported by National 973 Project China (grant No. 2013CB733305), NSFC (grant Nos. 41174011, 41210006, 41128003, 41021061).

  17. Inducing self-rotation of cells with natural and artificial melanin in a linearly polarized alternating current electric field

    PubMed Central

    Ouyang, Mengxing; Ki Cheung, Wing; Liang, Wenfeng; Mai, John D.; Keung Liu, Wing; Jung Li, Wen

    2013-01-01

    The phenomenon of self-rotation observed in naturally and artificially pigmented cells under an applied linearly polarized alternating current (non-rotating) electrical field has been investigated. The repeatable and controllable rotation speeds of the cells were quantified and their dependence on dielectrophoretic parameters such as frequency, voltage, and waveform was studied. Moreover, the rotation behavior of the pigmented cells with different melanin content was compared to quantify the correlation between self-rotation and the presence of melanin. Most importantly, macrophages, which did not originally rotate in the applied non-rotating electric field, began to exhibit self-rotation that was very similar to that of the pigmented cells, after ingesting foreign particles (e.g., synthetic melanin or latex beads). We envision the discovery presented in this paper will enable the development of a rapid, non-intrusive, and automated process to obtain the electrical conductivities and permittivities of cellular membrane and cytoplasm in the near future. PMID:24404075

  18. Polarization rotator-splitters and controllers in a Si3N4-on-SOI integrated photonics platform.

    PubMed

    Sacher, Wesley D; Huang, Ying; Ding, Liang; Barwicz, Tymon; Mikkelsen, Jared C; Taylor, Benjamin J F; Lo, Guo-Qiang; Poon, Joyce K S

    2014-05-01

    We demonstrate novel polarization management devices in a custom-designed silicon nitride (Si(3)N(4)) on silicon-on-insulator (SOI) integrated photonics platform. In the platform, Si(3)N(4) waveguides are defined atop silicon waveguides. A broadband polarization rotator-splitter using a TM0-TE1 mode converter in a composite Si(3)N(4)-silicon waveguide is demonstrated. The polarization crosstalk, insertion loss, and polarization dependent loss are less than -19 dB, 1.5 dB, and 1.0 dB, respectively, over a bandwidth of 80 nm. A polarization controller composed of polarization rotator-splitters, multimode interference couplers, and thin film heaters is also demonstrated. PMID:24921814

  19. Polar studies of the sphericity degree of V/HTR nuclear fuel particles

    SciTech Connect

    Robert-Inacio, F. . E-mail: frederique.robert@isen.fr; Boschet, C.; Charollais, F.

    2006-06-15

    Advanced nuclear power reactor designs such as (Very) High Temperature Reactors (V/HTR) employ TRISO fuel particles that typically have a sub-millimetre U-based fuel kernel coated with three isotropic ceramic layers-a layer of silicon carbide sandwiched between pyrocarbon layers of different density. Evaluation of the ceramic layer thickness and of the degree of sphericity of these typical nuclear fuel particles is required at each step of the fabrication, in order to estimate future fuel performance under irradiation conditions. This study is based on the image processing of polished cross-sections, realized near the equatorial plane. From these 2D images, some measurements are carried out, giving an estimation of the diameter values for a sample of particles at each step of the coating process. These values are then statistically extended to the third dimension in order to obtain the thickness of each layer and the degree of sphericity of each particle. A representation of diameter and layer thickness in polar coordinates enables one to identify steps for which the coating process is defective or deviating from nominal objectives.

  20. New Atmospheric and Oceanic Angular Momentum Datasets for Predictions of Earth Rotation/Polar Motion

    NASA Astrophysics Data System (ADS)

    Salstein, D. A.; Stamatakos, N.

    2014-12-01

    We are reviewing the state of the art in available datasets for both atmospheric angular momentum (AAM) and oceanic angular momentum (OAM) for the purposes of analysis and prediction of both polar motion and length of day series. Both analyses and forecasts of these quantities have been used separately and in combination to aid in short and medium range predictions of Earth rotation parameters. The AAM and OAM combination, with the possible addition of hydrospheric angular momentum can form a proxy index for the Earth rotation parameters themselves due to the conservation of angular momentum in the Earth system. Such a combination of angular momentum of the geophysical fluids has helped in forecasts within periods up to about 10 days, due to the dynamic models, and together with extended statistical predictions of Earth rotation parameters out even as far as 90 days, according to Dill et al. (2013). We assess other dataset combinations that can be used in such analysis and prediction efforts for the Earth rotation parameters, and demonstrate the corresponding skill levels in doing so.

  1. Photonic crystal fiber polarization rotator based on the topological Zeeman effect.

    PubMed

    Chen, Lei; Zhang, Wei-Gang; Yan, Tie-Yi; Wang, Li; Sieg, Jonathan; Wang, Biao; Zhou, Quan; Zhang, Li-Yu

    2015-08-01

    A photonic crystal fiber polarization rotator (PR) is proposed based on the topological Zeeman effect. The proposed PR is achieved by permanently twisting a segment of sixfold symmetric photonic crystal fiber with a matched length, and under the optimized parameters, the PR can offer an almost 100% polarization conversion ratio in the wavelength of 1.55-μm band (∼200  nm bandwidth) and a compact length of about 157 μm based on the numerical simulation result of the full-vector finite-element method. The proposed in-line PCF PR can be easily fabricated based on state-of-art PCF manufacturing, and it is a potential inexpensive candidate in the application of modern communication systems. PMID:26258329

  2. Quasiequilibrium nonlinearities in Faraday and Kerr rotation from spin-polarized carriers in GaAs

    NASA Astrophysics Data System (ADS)

    Joshua, Arjun; Venkataraman, V.

    2010-01-01

    Semiconductor Bloch equations (SBEs), which microscopically describe optical properties in terms of the dynamics of a Coulomb interacting, spin-unpolarized electron-hole plasma, can be solved in two limits: the coherent and the quasiequilibrium regimes. Recently, Nemec et al. [1] reported circularly polarized pump-probe absorption spectra in the quasiequilibrium regime for carrier spin-polarized bulk GaAs at room temperature, which lacked a suitable microscopic theoretical understanding. We have very recently explained their results by solving the spin-SBEs in the quasiequilibrium regime (spin-Bethe-Salpeter equation), and accounted for spin-dependent mechanisms of optical nonlinearity [2]. Here, we extend our theory to the microscopic calculation of Kerr and Faraday rotation in the quasiequilibrium regime, for which there are no experimental or theoretical results available.

  3. Anomalous incident-angle and elliptical-polarization rotation of an elastically refracted P-wave

    PubMed Central

    Fa, Lin; Fa, Yuxiao; Zhang, Yandong; Ding, Pengfei; Gong, Jiamin; Li, Guohui; Li, Lijun; Tang, Shaojie; Zhao, Meishan

    2015-01-01

    We report a newly discovered anomalous incident-angle of an elastically refracted P-wave, arising from a P-wave impinging on an interface between two VTI media with strong anisotropy. This anomalous incident-angle is found to be located in the post-critical incident-angle region corresponding to a refracted P-wave. Invoking Snell’s law for a refracted P-wave provides two distinctive solutions before and after the anomalous incident-angle. For an inhomogeneously refracted and elliptically polarized P-wave at the anomalous incident-angle, its rotational direction experiences an acute variation, from left-hand elliptical to right-hand elliptical polarization. The new findings provide us an enhanced understanding of acoustical-wave scattering and lead potentially to widespread and novel applications. PMID:26244284

  4. Evaluation of diseased coronary arterial branches by polar representations of thallium-201 rotational myocardial imaging

    SciTech Connect

    Iino, T.; Toyosaki, N.; Katsuki, T.; Noda, T.; Natsume, T.; Yaginuma, T.; Hosoda, S.; Furuse, M.

    1987-09-01

    The perfusion territories in polar representations of stress Tl-201 rotational myocardial imaging in patients with angina pectoris who had one diseased coronary segment were analyzed. The lesions proximal or distal to the first major septal perforator in left anterior descending arteries were detected by the presence or absence of defects at the base of the anterior septum. Right coronary artery lesions were detected by the presence of defects at the basal posterior septum, in contrast to the preservation of myocardial uptake at this portion in lesions of the left circumflex artery. The specific defect patterns were detected in cases with lesions at the first diagonal, obtuse marginal, and posterolateral branches. Recognition of these defects in the polar maps allows detailed detection of diseased coronary arterial branches.

  5. Vector carrier frequency by interfering the kth harmonic of two rulings rotated polarly

    NASA Astrophysics Data System (ADS)

    Meneses-Fabian, Cruz; Kantun-Montiel, Rosaura; Lemus-Alonso, Gildardo-Pablo

    2015-03-01

    This paper presents a method for introducing carrier fringes inclined at any angle into an interferogram. The setup is built on a 4f optical system consisting of two apertures in the input plane and a Ronchi ruling in the Fourier plane. Additionally, a Ronchi ruling rotated on polar direction is placed at each aperture and two passband filters are placed in the Fourier plane for filtering the kth harmonic of their spectra. We demonstrated that the magnitude and direction of the vector carrier frequency depend on the grating period at the input plane, the polar angles, and the kth harmonic, which gives this method the ability to modulate its magnitude only, or its direction only, or both in a wide range. The theoretical model and experimental results are shown in this paper.

  6. Reconstruction of polar magnetic field from single axis tomography of Faraday rotation in plasmas

    SciTech Connect

    Flacco, A.; Rax, J.-M.; Malka, V.

    2012-10-15

    An integral back-transform has been developed to retrieve the polar magnetic component in a cylindrically symmetric plasma from a single projection. The formula is derived from parallel forward Radon transform (Abel transform) of a source-free vector field. Two numerical schemes are proposed to solve the backward transform. These schemes have been tested successfully with predefined plasma parameters. The practical application to the analysis of experimental Faraday rotation measurements is also presented, leading to the reconstruction of the transverse profile of the magnetic field.

  7. High frequency optical pulse generation by frequency doubling using polarization rotation

    NASA Astrophysics Data System (ADS)

    Liu, Yang

    2016-05-01

    In this work, we propose and experimentally characterize a stable 40 GHz optical pulse generation by frequency doubling using polarization rotation in a phase modulator (PM). Only half the electrical driving frequency is required (i.e. 20 GHz); hence the deployment cost can be reduced. Besides, precise control of the bias of the PM is not required. The generated optical pulses have a high center-mode-suppression-ratio (CMSR) of  >  28 dB. The single sideband (SSB) noise spectrum is also measured, and the time-domain waveforms under different CMSRs are also analyzed and discussed.

  8. Analysis of High-Speed Rotating Flow in 2D Polar (r - θ)Coordinate

    NASA Astrophysics Data System (ADS)

    Pradhan, S.

    2016-03-01

    The generalized analytical model for the radial boundary layer in a high-speed rotating cylinder is formulated for studying the gas flow field due to insertion of mass, momentum and energy into the rotating cylinder in the polar (r - θ) plane. The analytical solution includes the sixth order differential equation for the radial boundary layer at the cylindrical curved surface in terms of master potential (χ) , which is derived from the equations of motion in a polar (r - θ) plane. The linearization approximation (Wood & Morton, J. Fluid Mech-1980; Pradhan & Kumaran, J. Fluid Mech-2011; Kumaran & Pradhan, J. Fluid Mech-2014) is used, where the equations of motion are truncated at linear order in the velocity and pressure disturbances to the base flow, which is a solid-body rotation. Additional assumptions in the analytical model include constant temperature in the base state (isothermal condition), and high Reynolds number, but there is no limitation on the stratification parameter. In this limit, the gas flow is restricted to a boundary layer of thickness (Re (1 / 3) R) at the wall of the cylinder. Here, the stratification parameter A = √ ((mΩ 2R2) / (2kB T)) . This parameter Ais the ratio of the peripheral speed, ΩR , to the most probable molecular speed, √(2 k_B T/m), the Reynolds number Re = (ρ _w ΩR2 / μ) , where m is the molecular mass, Ω and R are the rotational speed and radius of the cylinder, k_B is the Boltzmann constant, T is the gas temperature, ρ_w is the gas density at wall, and μ is the gas viscosity. The analytical solutions are then compared with direct simulation Monte Carlo (DSMC) simulations.

  9. INTEGRATED POLARIZATION OF SOURCES AT {lambda} {approx} 1 m AND NEW ROTATION MEASURE AMBIGUITIES

    SciTech Connect

    Farnsworth, Damon; Rudnick, Lawrence; Brown, Shea

    2011-06-15

    We present an analysis of the polarization of compact radio sources from six pointings of the Westerbork Synthesis Radio Telescope at 350 MHz with 35% coverage in {lambda}{sup 2}. After correcting for the off-axis instrumental polarization with a simple analytical model, only a small number of 585 strong sources have significant polarizations at these wavelengths. The median depolarization ratio from 1.4 GHz for the strongest sources is <0.2, reinforcing the likelihood that radio galaxies are found in magnetized environments, even outside of rich clusters. Seven sources with significant 350 MHz polarization were selected for a more in-depth Faraday structure analysis. We fit the observed values Q/I and U/I as a function of {lambda}{sup 2} using both a depolarizing screen and two-component models. We also performed rotation measure (RM) Synthesis/Clean and standard fitting of polarization angle versus {lambda}{sup 2}. We find that a single RM, as found using polarization angle fitting or simple screen models, commonly provides a poor fit when the solutions are translated back into Q, U space. Thus, although a single 'characteristic' RM may be found using these techniques, the Faraday structure of the source may not be adequately represented. We also demonstrate that RM Synthesis may yield an erroneous Faraday structure in the presence of multiple, interfering RM components, even when cleaning of the Faraday spectrum is performed. We briefly explore the conditions under which RMs and Faraday structure results can be reliable. Many measurements in the literature do not meet these criteria; we discuss how these influence the resulting scientific conclusions and offer a prescription for obtaining reliable RMs.

  10. Mode-locked fiber laser using the Sagnac interferometer and the nonlinear polarization rotation

    NASA Astrophysics Data System (ADS)

    Ibarra-Escamilla, Baldeamr; Kuzin, Evgueni A.; Haus, Joseph W.; Pottiez, Olivier; Gomez-Garcia, Dario E.; Gutierrez-Zainos, Francisco; Mendoza-Vazquez, Sergio; Grajales-Coutico, Ruben

    2003-07-01

    In figure-eight lasers (F8L) mode locking is achieved through a nonlinear fiber amplifier loop mirror (NALM) or an asymmetrical nonlinear optical loop mirror (NOLM). Recently, we have theoretically shown that the symmetrical NOLM with a twisted fiber is useful for passive mode locking of fiber lasers. In this work we experimentally demonstrate the operation of a F8L based on the symmetrical NOLM with a twisted low-birefringence fiber in the loop. The modelocking operation is achieved by nonlinear polarization rotation. We found that the counter-propagating beams accumulate a differential nonlinear phase shift when they have different As (where As is the Stokes parameter). At the input NOLM, we used a polarizer controller to adjust the clockwise beam to be circularly polarized, As=1. In the loop of the NOLM, we used a quarter-wave retarder to transform the counter-clockwise beam to linear polarization, As=0. The quarter-wave retarder was the only element that we adjust to achieve modelocking. The pulse repetition frequency was 0.8 MHz. The FWHM of the autocorrelation function was 0.7 ps. We used a pump power of 80 mW to get the modelocking operation. The modelocked laser ran in stable operation for hours. Even in this first experiments the laser shown several advantages. The adjustment procedure was straightforward. The laser shows stable operation and exhibits high pulse energy. We achieved stable generation of subpicosecond pulses with milliwatts of average output power.

  11. NMR Properties of the Polar Phase of Superfluid ^3He in Anisotropic Aerogel Under Rotation

    NASA Astrophysics Data System (ADS)

    Mineev, V. P.

    2016-09-01

    The polar phase of superfluid ^3He is stable in "nematically ordered" densed aerogel. A rotating vessel with the polar superfluid can be filled either by an array of the single quantum vortices or by an array of the half-quantum vortices. It is shown that the inhomogeneous distribution of the spin part of the order parameter arising in an array of half-quantum vortices in strong enough magnetic field tilted to the average direction of aerogel strands leads to the appearance of a satellite in the NMR signal shifted in the negative direction with respect to the Larmor frequency. The satellite is absent in the case of an array of single quantum vortices which allows to distinguish these two configurations. The polar state in the anisotropic aerogel with lower density transforms at lower temperatures to the axipolar state. The array of half-quantum vortices created in the polar phase keeps its structure under transition to the axipolar state. The temperature dependence of the vortex-satellite NMR frequency is found to be slower below the transition temperature to the axipolar state.

  12. Polar octahedral rotations, cation displacement and ferroelectricity in multiferroic SmCrO3

    NASA Astrophysics Data System (ADS)

    Ghosh, A.; Dey, K.; Chakraborty, M.; Majumdar, S.; Giri, S.

    2014-08-01

    Our thorough synchrotron diffraction studies provide a clue on the origin of ferroelectricity in SmCrO3. Careful observation demonstrates that polar order develops in the paramagnetic state. Rietveld refinement of the diffraction data confirms that emergence of polar order is correlated with the structural transformation from centrosymmetric Pbnm to non-centrosymmetric Pna21 space group of the distorted orthorhombic structure. Rotations of polar CrO6 octahedra and Sm displacement are proposed to be correlated with the emergence of polar order, which is extended over a wide temperature range and increases gradually with decreasing temperature. This is consistent with the relaxor behavior as evident from the frequency-dependent dielectric response satisfying the Vogel-Fulcher law. A non-collinear to collinear spin transformation is suggested well below the spin reorientation transition. Appearance of ferroelectricity without any correlation to the antiferromagnetic order in SmCrO3 suggests a new class of ferroelectricity. All-electron full-potential first-principles calculation demonstrates significant Sm-Cr hybridization near the Fermi level, which substantiates the experimental findings.

  13. NMR Properties of the Polar Phase of Superfluid ^3 He in Anisotropic Aerogel Under Rotation

    NASA Astrophysics Data System (ADS)

    Mineev, V. P.

    2016-04-01

    The polar phase of superfluid ^3 He is stable in "nematically ordered" densed aerogel. A rotating vessel with the polar superfluid can be filled either by an array of the single quantum vortices or by an array of the half-quantum vortices. It is shown that the inhomogeneous distribution of the spin part of the order parameter arising in an array of half-quantum vortices in strong enough magnetic field tilted to the average direction of aerogel strands leads to the appearance of a satellite in the NMR signal shifted in the negative direction with respect to the Larmor frequency. The satellite is absent in the case of an array of single quantum vortices which allows to distinguish these two configurations. The polar state in the anisotropic aerogel with lower density transforms at lower temperatures to the axipolar state. The array of half-quantum vortices created in the polar phase keeps its structure under transition to the axipolar state. The temperature dependence of the vortex-satellite NMR frequency is found to be slower below the transition temperature to the axipolar state.

  14. Polarity mechanisms such as contact inhibition of locomotion regulate persistent rotational motion of mammalian cells on micropatterns

    PubMed Central

    Camley, Brian A.; Zhang, Yunsong; Zhao, Yanxiang; Li, Bo; Ben-Jacob, Eshel; Levine, Herbert; Rappel, Wouter-Jan

    2014-01-01

    Pairs of endothelial cells on adhesive micropatterns rotate persistently, but pairs of fibroblasts do not; coherent rotation is present in normal mammary acini and kidney cells but absent in cancerous cells. Why? To answer this question, we develop a computational model of pairs of mammalian cells on adhesive micropatterns using a phase field method and study the conditions under which persistent rotational motion (PRM) emerges. Our model couples the shape of the cell, the cell’s internal chemical polarity, and interactions between cells such as volume exclusion and adhesion. We show that PRM can emerge from this minimal model and that the cell-cell interface may be influenced by the nucleus. We study the effect of various cell polarity mechanisms on rotational motion, including contact inhibition of locomotion, neighbor alignment, and velocity alignment, where cells align their polarity to their velocity. These polarity mechanisms strongly regulate PRM: Small differences in polarity mechanisms can create significant differences in collective rotation. We argue that the existence or absence of rotation under confinement may lead to insight into the cell’s methods for coordinating collective cell motility. PMID:25258412

  15. Effect of molecular anisotropy on the intensity and degree of polarization of light scattered from model atmospheres

    NASA Technical Reports Server (NTRS)

    Bahethi, O. P.; Fraser, R. S.

    1975-01-01

    Computations of the intensity, flux, degree of polarization, and the positions of neutral points are presented for models of the terrestrial gaseous and hazy atmospheres by incorporating the molecular anisotropy due to air in the Rayleigh scattering optical thickness and phase matrix. Molecular anisotropy causes significant changes in the intensity, flux and the degree of polarization of the scattered light. The positions of neutral points do not change significantly. When the Rayleigh scattering optical thickness is kept constant and the molecular anisotropy factor is included only in the Rayleigh phase matrix, the flux does not change and the intensity and positions of neutron points change by a small amount. The changes in the degree of polarization are still significant.

  16. Subnanosecond polarized fluorescence photobleaching: rotational diffusion of acetylcholine receptors on developing muscle cells.

    PubMed Central

    Yuan, Y; Axelrod, D

    1995-01-01

    Polarized fluorescence recovery after photobleaching (PFRAP) is a technique for measuring the rate of rotational motion of biomolecules on living, nondeoxygenated cells with characteristic times previously ranging from milliseconds to many seconds. Although very broad, that time range excludes the possibility of quantitatively observing freely rotating membrane protein monomers that typically should have a characteristic decay time of only several microseconds. This report describes an extension of the PFRAP technique to a much shorter time scale. With this new system, PFRAP experiments can be conducted with sample time as short as 0.4 microseconds and detection of possible characteristic times of less than 2 microseconds. The system is tested on rhodamine-alpha-bungarotoxin-labeled acetylcholine receptors (AChRs) on myotubes grown in primary cultures of embryonic rat muscle, in both endogenously clustered and nonclustered regions of AChR distribution. It is found that approximately 40% of the AChRs in nonclustered regions undergoes rotational diffusion fast enough to possibly arise from unrestricted monomer Brownian motion. The AChRs in clusters, on the other hand, are almost immobile. The effects of rat embryonic brain extract (which contains AChR aggregating factors) on the myotube AChR were also examined by the fast PFRAP system. Brain extract is known to abolish the presence of endogenous clusters and to induce the formation of new clusters. It is found here that rotational diffusion of AChR in the extract-induced clusters is as slow as that in endogenous clusters on untreated cells but that rotational diffusion in the nonclustered regions of extract-treated myotubes remains rapid. Images FIGURE 3 PMID:8527682

  17. Mode-evolution-based polarization rotation and coupling between silicon and hybrid plasmonic waveguides

    PubMed Central

    Kim, Sangsik; Qi, Minghao

    2015-01-01

    Hybrid plasmonic (HP) modes allow strong optical field confinement and simultaneously low propagation loss, offering a potentially compact and efficient platform for on-chip photonic applications. However, their implementation is hampered by the low coupling efficiency between dielectric guided modes and HP modes, caused by mode mismatch and polarization difference. In this work, we present a mode-evolution-based polarization rotation and coupling structure that adiabatically rotates the TE mode in a silicon waveguide and couples it to the HP mode in a strip silicon-dielectric-metal waveguide. Simulation shows that high coupling factors of 92%, 78%, 75%, and 73% are achievable using Ag, Au, Al, and Cu as the metal cap, respectively, at a conversion length of about 5 μm. For an extremely broad wavelength range of 1300–1800 nm, the coupling factor is >64% with a Ag metal cap, and the total back-reflection power, including all the mode reflections and backscattering, is below −40 dB, due to the adiabatic mode transition. Our device does not require high-resolution lithography and is tolerant to fabrication variations and imperfections. These attributes together make our device suitable for optical transport systems spanning all telecommunication bands. PMID:26680655

  18. Determination of polar motion and earth rotation from laser tracking of satellites

    NASA Technical Reports Server (NTRS)

    Smith, D. E.; Kolenkiewicz, R.; Dunn, P. J.; Torrence, M.

    1979-01-01

    Laser tracking of the Lageos spacecraft has been used to derive the position of the earth's pole of rotation at intervals during October, November and December 1976. The estimated precision of the results is 0.01 to 0.02 arcseconds in both x and y components, although the formal uncertainty is an order of magnitude better, and there is general agreement with the Bureau International de l'Heure smoothed pole path to about 0.02 arcseconds. Present orbit determination capability of Lageos is limited to about 25 cm rms fit to data over periods of 5 days and about 50 cm over 50 days. The present major sources of error in the perturbations of Lageos are earth and ocean tides followed by the earth's gravity field, and solar and earth reflected radiation pressure. Ultimate accuracy for polar motion and earth rotation from Lageos after improved modeling of the perturbing forces appears to be of order + or - 5 cm for polar motion over a period of about one day and about + or - 0.2 to + or - 0.3 milliseconds in UT for periods up to 2 or 3 months.

  19. Effect of molecular anisotropy on the intensity and degree of polarization of light scattered from model atmospheres

    NASA Technical Reports Server (NTRS)

    Bahethi, O. P.; Fraser, R. S.

    1980-01-01

    Computations of the properties of sunlight scattered from models of the earth-atmosphere system are presented to show the effect of molecular anisotropy on the intensity, flux, and degree of polarization of the scattered light. The values of these parameters change significantly when the anisotropy factor is neglected in the molecular optical thickness and scattering phase matrix. However, if the Rayleigh scattering optical thickness is kept constant and the molecular anisotropy factor is included only in the Rayleigh phase matrix, the flux does not change, the intensity changes by a small amount, but the changes in the degree of polarization are still significant.

  20. {100}<100> or 45.degree.-rotated {100}<100>, semiconductor-based, large-area, flexible, electronic devices

    SciTech Connect

    Goyal, Amit

    2012-05-15

    Novel articles and methods to fabricate the same resulting in flexible, {100}<100> or 45.degree.-rotated {100}<100> oriented, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  1. Blastomeres show differential fate changes in 8-cell Xenopus laevis embryos that are rotated 90 degrees before first cleavage

    NASA Technical Reports Server (NTRS)

    Huang, S.; Johnson, K. E.; Wang, H. Z.

    1998-01-01

    To study the mechanisms of dorsal axis specification, the alteration in dorsal cell fate of cleavage stage blastomeres in axis-respecified Xenopus laevis embryos was investigated. Fertilized eggs were rotated 90 degrees with the sperm entry point up or down with respect to the gravitational field. At the 8-cell stage, blastomeres were injected with the lineage tracers, Texas Red- or FITC-Dextran Amines. The distribution of the labeled progeny was mapped at the tail-bud stages (stages 35-38) and compared with the fate map of an 8-cell embryo raised in a normal orientation. As in the normal embryos, each blastomere in the rotated embryos has a characteristic and predictable cell fate. After 90 degrees rotation the blastomeres in the 8-cell stage embryo roughly switched their position by 90 degrees, but the fate of the blastomeres did not simply show a 90 degrees switch appropriate for their new location. Four types of fate change were observed: (i) the normal fate of the blastomere is conserved with little change; (ii) the normal fate is completely changed and a new fate is adopted according to the blastomere's new position: (iii) the normal fate is completely changed, but the new fate is not appropriate for its new position; and (4) the blastomere partially changed its fate and the new fate is a combination of its original fate and a fate appropriate to its new location. According to the changed fates, the blastomeres that adopt dorsal fates were identified in rotated embryos. This identification of dorsal blastomeres provides basic important information for further study of dorsal signaling in Xenopus embryos.

  2. Polar cap models of gamma-ray pulsars: Emision from single poles of nearly aligned rotators

    NASA Technical Reports Server (NTRS)

    Daugherty, Joseph K.; Harding, Alice K.

    1994-01-01

    We compare a new Monte Carlo simulation of polar cap models for gamma-ray pulsars with observations of sources detected above 10 MeV by the Compton Observatory (CGRO). We find that for models in which the inclination of the magnetic axis is comparable to the angular radius of the polar cap, the radiation from a single cap may exhibit a pusle with either a single broad peak as in PSR 1706-44 and PSR 1055-52, or a doubly peaked profile comparable to those observed from the Crab, Vela and Geminga pulsars. In general, double pulses are seen by observers whose line of sight penetrates into the cap interior and are due to enhanced emission near the rim. For cascades induced by culvature radiation, increased rim emission occurs even when electrons are accelerated over the entire cap, since electrons from the interior escape along magnetic field lines with less curvature and hence emit less radiation. However, we obtain better fits to the duty cycles of observed profiles if we make the empirical assumption that acceleration occurs only near the rim. In either case, the model energy spectra are consistent with most of the observed sources. The beaming factors expected from nearly aligned rotators, based on standard estimates for the cap radius, imply that their luminosities need not be as large as in the case of orthogonal rotators. However, small beam angles are also a difficutly with this model because they imply low detection probablities. In either case the polar cap radius is a critical factor, and in this context we point out that plasma loading of the field lines should make the caps larger than the usual estimates based on pure dipole fields.

  3. Correlated polarization switching in the proximity of a 180 degrees domain wall

    SciTech Connect

    Aravind, Vasudeva Rao; Morozovska, A. N.; Bhattacharya, S.; Lee, Dongwa; Jesse, Stephen; Grinberg, I; Li, Y L; Choudhury, S; Wu, P; Seal, Katyayani; Rappe, Andrew M; Rar, Andrei; Svechnikov, S. V.; Eliseev, Eugene; Phillpot, S. R.; Chen, L. Q.; Gopalana, V.; Kalinin, Sergei V

    2010-01-01

    Domain-wall dynamics in ferroic materials underpins functionality of data storage and information technology devices. Using localized electric field of a scanning probe microscopy tip, we experimentally demonstrate a surprisingly rich range of polarization reversal behaviors in the vicinity of the initially flat 180 degrees ferroelectric domain wall. The nucleation bias is found to increase by an order of magnitude from a two-dimensional (2D) nucleus at the wall to three-dimensional nucleus in the bulk. The wall is thus significantly ferroelectrically softer than the bulk. The wall profoundly affects switching on length scales on the order of micrometers. The mechanism of correlated switching is analyzed using analytical theory and phase-field modeling. The long-range effect is ascribed to wall bending under the influence of a tip with bias that is well below the bulk nucleation level at large distances from the wall. These studies provide an experimental link between the macroscopic and mesoscopic physics of domain walls in ferroelectrics and atomistic models of 2D nucleation.

  4. CMOS-compatible polarization rotator design based on asymmetrical periodic loaded waveguide structure

    NASA Astrophysics Data System (ADS)

    Sun, Yao; Ye, Winnie N.

    2016-03-01

    Silicon-on-insulator (SOI) technology has been a promising platform for photonic applications. However, the high index-contrast between silicon and the top cladding (SiO2 or air) of the SOI waveguides makes the modal birefringence hard to control. Consequently, SOI based photonics integrated circuits (PICs) are in general highly polarization-sensitive, making polarization management important. In this paper, a polarization rotator (PR) design on the 220 nm SOI platform is demonstrated through numerical simulations and experiments. The demonstrated PR design is based on asymmetrical periodic loaded waveguide structures. The demonstrated design features compact device footprint and can be fabricated by CMOS compatible process. In addition, no special cladding is required to break the vertical symmetry of the waveguide. The design has shown promising performance over the C-band wavelengths (1530 nm-1565 nm) by simulations. However, the fabrication requirements are stringent for the design, thus the performance of the fabricated devices are limited by the current fabrication technology.

  5. The polarization electric field and its effects in an anisotropic rotating magnetospheric plasma

    NASA Technical Reports Server (NTRS)

    Huang, T. S.; Birmingham, T. J.

    1992-01-01

    Spatial variations of density and temperature along a magnetic field line are evaluated for a plasma undergoing adiabatic motion in a rotating magnetosphere. The effects of centrifugal and gravitational forces are accounted for, as is anisotropy in the pitch angle distribution functions of individual species. A polarization electric field is invoked to eliminate the net electric charge density resulting from the aforementioned mass dependent forces and different anisotropies. The position of maximum density in a two-component, electron-ion plasma is determined both in the absence and in the presence of the polarization effect and compared. A scale height, generalized to include anisotropies, is derived for the density fall-off. The polarization electric field is also included in the parallel guiding center equation; equilibrium points are determined and compared in both individual and average senses with the position of density maximum. Finally a transverse (to magnetic field lines) electric component is deduced as a consequence of dissimilar charge neutralization on adjacent field lines. The E x B velocity resultant from such a 'fringing' electric field is calculated and compared with the magnitude of other drifts.

  6. Climatic impact of glacial cycle polar motion: Coupled oscillations of ice sheet mass and rotation pole position

    USGS Publications Warehouse

    Bills, Bruce G.; James, Thomas S.; Mengel, John G.

    1999-01-01

    Precessional motion of Earth's rotation axis relative to its orbit is a well-known source of long-period climatic variation. It is less well appreciated that growth and decay of polar ice sheets perturb the symmetry of the global mass distribution enough that the geographic location of the rotation axis will change by at least 15 km and possibly as much as 100 km during a single glacial cycle. This motion of the pole will change the seasonal and latitudinal pattern of temperatures. We present calculations, based on a diurnal average energy balance, which compare the summer and winter temperature anomalies due to a 1° decrease in obliquity with those due to a 1° motion of the rotation pole toward Hudson Bay. Both effects result in peak temperature perturbations of about 1° Celsius. The obliquity change primarily influences the amplitude of the seasonal cycle, while the polar motion primarily changes the annual mean temperatures. The polar motion induced temperature anomaly is such that it will act as a powerful negative feedback on ice sheet growth. We also explore the evolution of the coupled system composed of ice sheet mass and pole position. Oscillatory solutions result from the conflicting constraints of rotational and thermal stability. A positive mass anomaly on an otherwise featureless Earth is in rotational equilibrium only at the poles or the equator. The two polar equilibria are rotationally unstable, and the equatorial equilibrium, though rotationally stable, is thermally unstable. We find that with a plausible choice for the strength of coupling between the thermal and rotational systems, relatively modest external forcing can produce significant response at periods of 104–106 years, but it strongly attenuates polar motion at longer periods. We suggest that these coupled oscillations may contribute to the observed dominance of 100 kyr glacial cycles since the mid-Pleistocene and will tend to stabilize geographic patterns that are suitable to

  7. Designing Ferroelectric Field-Effect Transistors Based on the Polarization-Rotation Effect for Low Operating Voltage and Fast Switching

    NASA Astrophysics Data System (ADS)

    Qi, Yubo; Rappe, Andrew M.

    2015-10-01

    The effect of polarization rotation on the performance of metal-oxide-semiconductor field-effect transistors is investigated with a Landau-Ginzburg-Devonshire theory-based model. In this analytical model, the depolarization field, polarization rotations, and electrostatic properties of the doped silicon substrate are considered to illustrate the size effect of ferroelectric oxides and the stability of polarization in each direction. Based on this model, we provide guidance in designing electronic logic devices with low operating voltages and low active-energy consumption: First, we demonstrate that MOSFET operation could be achieved by polarization reorientation with a low operating voltage, if the thickness of the ferroelectric oxide is properly selected. Polarization reorientation can boost the surface potential of the silicon substrate, leading to a subthreshold swing S lower than 60 mV /decade . We also demonstrate that, compared with polarization inversion, polarization rotation offers significant advantages, including a lower energy barrier and a wider range of transferability in nanoelectronic devices.

  8. Influence of third-degree geometric nonlinearities on the vibration and stability of pretwisted, preconed, rotating blades

    NASA Technical Reports Server (NTRS)

    Subrahmanyam, K. B.; Kaza, K. R. V.

    1986-01-01

    The governing coupled flapwise bending, edgewise bending, and torsional equations are derived including third-degree geometric nonlinear elastic terms by making use of the geometric nonlinear theory of elasticity in which the elongations and shears are negligible compared to unity. These equations are specialized for blades of doubly symmetric cross section with linear variation of pretwist over the blade length. The nonlinear steady state equations and the linearized perturbation equations are solved by using the Galerkin method, and by utilizing the nonrotating normal modes for the shape functions. Parametric results obtained for various cases of rotating blades from the present theoretical formulation are compared to those produced from the finite element code MSC/NASTRAN, and also to those produced from an in-house experimental test rig. It is shown that the spurious instabilities, observed for thin, rotating blades when second degree geometric nonlinearities are used, can be eliminated by including the third-degree elastic nonlinear terms. Furthermore, inclusion of third degree terms improves the correlation between the theory and experiment.

  9. Ultra-compact and fabrication-tolerant polarization rotator based on a bend asymmetric-slab waveguide.

    PubMed

    Cao, Tongtong; Chen, Shaowu; Fei, Yonghao; Zhang, Libin; Xu, Qing-Yang

    2013-02-10

    We propose and analyze a polarization rotator based on a bend asymmetric-slab waveguide on the silicon-on-insulator platform. The device can be fabricated using standard complementary metal-oxide-semiconductor process involving only two dry etching steps. Compared with the formerly reported polarization rotators based on two-step etching, our introduced device demonstrates a significant improvement for fabrication tolerance. Furthermore, an ultra compact structure of ~5 μm conversion length, an insertion loss of only 0.5 dB, and an extinction ratio of >40 dB for both TE to TM polarization conversion and TM to TE polarization conversion are exhibited. Operation wavelength and the influence of environmental temperature on our device are also discussed. PMID:23400060

  10. Computational efficiency improvement with Wigner rotation technique in studying atoms in intense few-cycle circularly polarized pulses

    SciTech Connect

    Yuan, Minghu; Feng, Liqiang; Lü, Rui; Chu, Tianshu E-mail: tschu008@163.com

    2014-02-21

    We show that by introducing Wigner rotation technique into the solution of time-dependent Schrödinger equation in length gauge, computational efficiency can be greatly improved in describing atoms in intense few-cycle circularly polarized laser pulses. The methodology with Wigner rotation technique underlying our openMP parallel computational code for circularly polarized laser pulses is described. Results of test calculations to investigate the scaling property of the computational code with the number of the electronic angular basis function l as well as the strong field phenomena are presented and discussed for the hydrogen atom.

  11. Computational efficiency improvement with Wigner rotation technique in studying atoms in intense few-cycle circularly polarized pulses.

    PubMed

    Yuan, Minghu; Lü, Rui; Feng, Liqiang; Chu, Tianshu

    2014-02-21

    We show that by introducing Wigner rotation technique into the solution of time-dependent Schrödinger equation in length gauge, computational efficiency can be greatly improved in describing atoms in intense few-cycle circularly polarized laser pulses. The methodology with Wigner rotation technique underlying our openMP parallel computational code for circularly polarized laser pulses is described. Results of test calculations to investigate the scaling property of the computational code with the number of the electronic angular basis function l as well as the strong field phenomena are presented and discussed for the hydrogen atom. PMID:24559339

  12. Effects of polar ice on the earth's rotation and gravitational potential

    NASA Technical Reports Server (NTRS)

    Trupin, Andrew S.

    1993-01-01

    The contributions of the Antarctic and the Greenland ice sheets to the earth's gravity, displacement, and rotation are estimated using gridded values of the net surface accumulation rates in the ice sheets of these two regions. It is found that the contributions to the low-order zonal harmonic coefficients of the earth's gravitational potential from Antarctica are between 2 and 10 times larger than the uncertainties of the zonal harmonics derived from satellite solutions; for Greenland, the coefficients are within an order of magnitude of the uncertainties of the satellite solutions. Polar contributions to the displacement of the center of mass of the solid earth, as seen in the frame of reference of satellites tracked from the earth surface, range from less than 1 mm to 1.5 cm over a 60-yr period.

  13. All-reflective, highly accurate polarization rotator for high-power short-pulse laser systems.

    PubMed

    Keppler, S; Hornung, M; Bödefeld, R; Kahle, M; Hein, J; Kaluza, M C

    2012-08-27

    We present the setup of a polarization rotating device and its adaption for high-power short-pulse laser systems. Compared to conventional halfwave plates, the all-reflective principle using three zero-phase shift mirrors provides a higher accuracy and a higher damage threshold. Since plan-parallel plates, e.g. these halfwave plates, generate postpulses, which could lead to the generation of prepulses during the subsequent laser chain, the presented device avoids parasitic pulses and is therefore the preferable alternative for high-contrast applications. Moreover the device is easily scalable for large beam diameters and its spectral reflectivity can be adjusted by an appropriate mirror coating to be well suited for ultra-short laser pulses. PMID:23037123

  14. Faraday rotation from magnesium II absorbers toward polarized background radio sources

    SciTech Connect

    Farnes, J. S.; O'Sullivan, S. P.; Corrigan, M. E.; Gaensler, B. M.

    2014-11-01

    Strong singly ionized magnesium (Mg II) absorption lines in quasar spectra typically serve as a proxy for intervening galaxies along the line of sight. Previous studies have found a correlation between the number of these Mg II absorbers and the Faraday rotation measure (RM) at ≈5 GHz. We cross-match a sample of 35,752 optically identified non-intrinsic Mg II absorption systems with 25,649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum and steep-spectrum subsamples. We find that our flat-spectrum sample shows significant (∼3.5σ) evidence for a correlation between Mg II absorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such correlation. We argue that such an effect cannot be explained by either luminosity or other observational effects, by evolution in another confounding variable, by wavelength-dependent polarization structure in an active galactic nucleus, by the Galactic foreground, by cosmological expansion, or by partial coverage models. We conclude that our data are most consistent with intervenors directly contributing to the Faraday rotation along the line of sight, and that the intervening systems must therefore have coherent magnetic fields of substantial strength ( B-bar =1.8±0.4 μG). Nevertheless, the weak nature of the correlation will require future high-resolution and broadband radio observations in order to place it on a much firmer statistical footing.

  15. Influence of collision energy and reagent rotation on the cross sections and product polarizations of the reaction F+ HCl

    NASA Astrophysics Data System (ADS)

    Duan, Zhi Xin; Li, Wen Liang; Qiu, Ming Hui

    2012-04-01

    Quasiclassical trajectory calculations have been carried out for the F+HCl reaction in three dimensions on a recent DHSN PES of the ground 12A' electronic state [M. P. Deskevich, M. Y. Hayes, K. Takahashi, R. T. Skodje, and D. J. Nesbitt, J. Chem. Phys. 124, 224303 (2006)]. The effects of the collision energy and the reagent initial rotational excitation on the cross sections and product polarization are studied for the v = 0 and j ⩽ 10 states of HCl over a wide collision energy range. It has been found that either the collision energy or the HCl rotational excitation increase remarkably reaction cross sections. The QCT-calculated integral cross sections are in good agreement with previous QM results. A detailed study on product polarization for the title reaction is also performed. The calculated results show that the product rotational angular momentum j' is not only aligned, but also oriented along the direction perpendicular to the scattering plane. The orientation of the HF product rotational angular momentum vector j' depends very sensitively on the collision energy and also affected by the reagent rotation. The theoretical findings and especially the roles of the collision energy and initial rotational momentum on the product polarization are discussed and reasonably explained by the HLH mass combination, the property of the PES, as well as the reactive mechanism.

  16. Chaos synchronization in vertical-cavity surface-emitting laser based on rotated polarization-preserved optical feedback

    NASA Astrophysics Data System (ADS)

    Nazhan, Salam; Ghassemlooy, Zabih; Busawon, Krishna

    2016-01-01

    In this paper, the influence of the rotating polarization-preserved optical feedback on the chaos synchronization of a vertical-cavity surface-emitting laser (VCSEL) is investigated experimentally. Two VCSELs' polarization modes (XP) and (YP) are gradually rotated and re-injected back into the VCSEL. The anti-phase dynamics synchronization of the two polarization modes is evaluated using the cross-correlation function. For a fixed optical feedback, a clear relationship is found between the cross-correlation coefficient and the polarization angle θp. It is shown that high-quality anti-phase polarization-resolved chaos synchronization is achieved at higher values of θp. The maximum value of the cross-correlation coefficient achieved is -0.99 with a zero time delay over a wide range of θp beyond 65° with a poor synchronization dynamic at θp less than 65°. Furthermore, it is observed that the antiphase irregular oscillation of the XP and YP modes changes with θp. VCSEL under the rotating polarization optical feedback can be a good candidate as a chaotic synchronization source for a secure communication system.

  17. ROTATING MOTIONS AND MODELING OF THE ERUPTING SOLAR POLAR-CROWN PROMINENCE ON 2010 DECEMBER 6

    SciTech Connect

    Su, Yingna; Van Ballegooijen, Adriaan

    2013-02-10

    A large polar-crown prominence composed of different segments spanning nearly the entire solar disk erupted on 2010 December 6. Prior to the eruption, the filament in the active region part split into two layers: a lower layer and an elevated layer. The eruption occurs in several episodes. Around 14:12 UT, the lower layer of the active region filament breaks apart: One part ejects toward the west, while the other part ejects toward the east, which leads to the explosive eruption of the eastern quiescent filament. During the early rise phase, part of the quiescent filament sheet displays strong rolling motion (observed by STEREO-B) in the clockwise direction (viewed from east to west) around the filament axis. This rolling motion appears to start from the border of the active region, then propagates toward the east. The Atmospheric Imaging Assembly (AIA) observes another type of rotating motion: In some other parts of the erupting quiescent prominence, the vertical threads turn horizontal, then turn upside down. The elevated active region filament does not erupt until 18:00 UT, when the erupting quiescent filament has already reached a very large height. We develop two simplified three-dimensional models that qualitatively reproduce the observed rolling and rotating motions. The prominence in the models is assumed to consist of a collection of discrete blobs that are tied to particular field lines of a helical flux rope. The observed rolling motion is reproduced by continuous twist injection into the flux rope in Model 1 from the active region side. Asymmetric reconnection induced by the asymmetric distribution of the magnetic fields on the two sides of the filament may cause the observed rolling motion. The rotating motion of the prominence threads observed by AIA is consistent with the removal of the field line dips in Model 2 from the top down during the eruption.

  18. Random Forest and Rotation Forest for fully polarized SAR image classification using polarimetric and spatial features

    NASA Astrophysics Data System (ADS)

    Du, Peijun; Samat, Alim; Waske, Björn; Liu, Sicong; Li, Zhenhong

    2015-07-01

    Fully Polarimetric Synthetic Aperture Radar (PolSAR) has the advantages of all-weather, day and night observation and high resolution capabilities. The collected data are usually sorted in Sinclair matrix, coherence or covariance matrices which are directly related to physical properties of natural media and backscattering mechanism. Additional information related to the nature of scattering medium can be exploited through polarimetric decomposition theorems. Accordingly, PolSAR image classification gains increasing attentions from remote sensing communities in recent years. However, the above polarimetric measurements or parameters cannot provide sufficient information for accurate PolSAR image classification in some scenarios, e.g. in complex urban areas where different scattering mediums may exhibit similar PolSAR response due to couples of unavoidable reasons. Inspired by the complementarity between spectral and spatial features bringing remarkable improvements in optical image classification, the complementary information between polarimetric and spatial features may also contribute to PolSAR image classification. Therefore, the roles of textural features such as contrast, dissimilarity, homogeneity and local range, morphological profiles (MPs) in PolSAR image classification are investigated using two advanced ensemble learning (EL) classifiers: Random Forest and Rotation Forest. Supervised Wishart classifier and support vector machines (SVMs) are used as benchmark classifiers for the evaluation and comparison purposes. Experimental results with three Radarsat-2 images in quad polarization mode indicate that classification accuracies could be significantly increased by integrating spatial and polarimetric features using ensemble learning strategies. Rotation Forest can get better accuracy than SVM and Random Forest, in the meantime, Random Forest is much faster than Rotation Forest.

  19. Optically controlled microwave phase shifter based on nonlinear polarization rotation in a highly nonlinear fiber.

    PubMed

    Li, Wei; Sun, Wen Hui; Wang, Wen Ting; Zhu, Ning Hua

    2014-06-01

    This Letter reports an optically controlled microwave phase shifter with an ultra-wideband working bandwidth and a full 360° phase shifting range based on nonlinear polarization rotation (NPR) in a highly nonlinear fiber (HNLF). A continuous wave probe light is modulated by a polarization modulator (PolM) that is driven by a microwave signal to be phase shifted. The optical carrier and the first-order sidebands of the probe light experience different phase shifts due to the NPR induced by the control light in the HNLF. An optical bandpass filter is used to realize single-sideband modulation of the probe light by removing one of the first-order sidebands, as well as to reject the control light. After detecting by a photodetector, the phase of the recovered microwave signal is continuously tunable by adjusting the power of the control light. The proposed approach is theoretically analyzed and experimentally verified. A full 360° tunable phase shift is realized over an ultra-wideband frequency range from 8 to 38 GHz when the power of the control light is tuned from 0 to 570 mW. PMID:24876035

  20. Structured caustic vector vortex optical field: manipulating optical angular momentum flux and polarization rotation

    PubMed Central

    Chen, Rui-Pin; Chen, Zhaozhong; Chew, Khian-Hooi; Li, Pei-Gang; Yu, Zhongliang; Ding, Jianping; He, Sailing

    2015-01-01

    A caustic vector vortex optical field is experimentally generated and demonstrated by a caustic-based approach. The desired caustic with arbitrary acceleration trajectories, as well as the structured states of polarization (SoP) and vortex orders located in different positions in the field cross-section, is generated by imposing the corresponding spatial phase function in a vector vortex optical field. Our study reveals that different spin and orbital angular momentum flux distributions (including opposite directions) in different positions in the cross-section of a caustic vector vortex optical field can be dynamically managed during propagation by intentionally choosing the initial polarization and vortex topological charges, as a result of the modulation of the caustic phase. We find that the SoP in the field cross-section rotates during propagation due to the existence of the vortex. The unique structured feature of the caustic vector vortex optical field opens the possibility of multi-manipulation of optical angular momentum fluxes and SoP, leading to more complex manipulation of the optical field scenarios. Thus this approach further expands the functionality of an optical system. PMID:26024434

  1. High degree of polarization of the near-band-edge photoluminescence in ZnO nanowires

    PubMed Central

    2011-01-01

    We investigated the polarization dependence of the near-band-edge photoluminescence in ZnO strain-free nanowires grown by vapor phase technique. The emission is polarized perpendicular to the nanowire axis with a large polarization ratio (as high as 0.84 at 4.2 K and 0.63 at 300 K). The observed polarization ratio is explained in terms of selection rules for excitonic transitions derived from the k·p theory for ZnO. The temperature dependence of the polarization ratio evidences a gradual activation of the XC excitonic transition. PACS: 78.55.Cr, 77.22.Ej, 81.07.Gf. PMID:21854578

  2. Three-party Quantum Secure Direct Communication with Single Photons in both Polarization and Spatial-mode Degrees of Freedom

    NASA Astrophysics Data System (ADS)

    Wang, LiLi; Ma, WenPing; Wang, MeiLing; Shen, DongSu

    2016-05-01

    We present an efficient three-party quantum secure direct communication (QSDC) protocol with single photos in both polarization and spatial-mode degrees of freedom. The three legal parties' messages can be encoded on the polarization and the spatial-mode states of single photons independently with desired unitary operations. A party can obtain the other two parties' messages simultaneously through a quantum channel. Because no extra public information is transmitted in the classical channels, the drawback of information leakage or classical correlation does not exist in the proposed scheme. Moreover, the comprehensive security analysis shows that the presented QSDC network protocol can defend the outsider eavesdropper's several sorts of attacks. Compared with the single photons with only one degree of freedom, our protocol based on the single photons in two degrees of freedom has higher capacity. Since the preparation and the measurement of single photon quantum states in both the polarization and the spatial-mode degrees of freedom are available with current quantum techniques, the proposed protocol is practical.

  3. Measuring cloud droplet effective radius and liquid water content using changes in degree of linear polarization along cloud depth.

    PubMed

    Kim, Dukhyeon; Lee, Jeongsoon

    2014-06-15

    Two important parameters of liquid clouds are the cloud effective size (CES) and liquid water content (LWC). To measure these parameters, we have used two multiple scattering depolarization effects: (1) the slope of the degree of linear polarization (SLDLP) at the cloud base, and (2) the saturated degree of linear polarization (SADLP) at infinite altitude. We used Monte Carlo simulation to validate this method, with the assumption that the water cloud droplet size follows a Gamma distribution. From our calculation, we find that although the SADLP varies with both extinction coefficient (or LWC) and the CES, the SLDLP varies only with the extinction coefficient. After extracting the extinction coefficient using the SLDLP, we can easily obtain the CES using the SADLP. As a result, we found that the CES and the LWC can be extracted from the experimental parameters of SLDLP and SADLP, which can be easily measured using a single wavelength depolarization LIDAR. PMID:24978490

  4. Comparative analysis on arthroscopic sutures of large and extensive rotator cuff injuries in relation to the degree of osteopenia☆

    PubMed Central

    Almeida, Alexandre; Atti, Vinícius; Agostini, Daniel Cecconi; Valin, Márcio Rangel; de Almeida, Nayvaldo Couto; Agostini, Ana Paula

    2015-01-01

    Objective To analyze the results from arthroscopic suturing of large and extensive rotator cuff injuries, according to the patient's degree of osteopenia. Method 138 patients who underwent arthroscopic suturing of large and extensive rotator cuff injuries between 2003 and 2011 were analyzed. Those operated from October 2008 onwards formed a prospective cohort, while the remainder formed a retrospective cohort. Also from October 2008 onwards, bone densitometry evaluation was requested at the time of the surgical treatment. For the patients operated before this date, densitometry examinations performed up to two years before or after the surgical treatment were investigated. The patients were divided into three groups. Those with osteoporosis formed group 1 (n = 16); those with osteopenia, group 2 (n = 33); and normal individuals, group 3 (n = 55). Results In analyzing the University of California at Los Angeles (UCLA) scores of group 3 and comparing them with group 2, no statistically significant difference was seen (p = 0.070). Analysis on group 3 in comparison with group 1 showed a statistically significant difference (p = 0.027). Conclusion The results from arthroscopic suturing of large and extensive rotator cuff injuries seem to be influenced by the patient's bone mineral density, as assessed using bone densitometry. PMID:26229899

  5. Efficient Bidirectional Quantum Secure Direct Communication with Single Photons in Both Polarization and Spatial-Mode Degrees of Freedom

    NASA Astrophysics Data System (ADS)

    Wang, L. L.; Ma, W. P.; Shen, D. S.; Wang, M. L.

    2015-10-01

    With single photos in both polarization and spatial-mode degrees of freedom,we present an efficient bidirectional quantum secure direct communication (QSDC) protocol is proposed. The participants' secret messages can be transmitted directly in a quantum channel through performing different local unitary operations, which are chosen by the two participants separately from the Pauli operations and Hadamard operations, on the polarization states and the spatial-mode states of single photons. Each single photon in two degrees of freedom can carry two bits of information. Thus the capacity of quantum communication of our protocol is improved. Moreover, we discuss the security of our QSDC network protocol comprehensively. It is showed that the proposed scheme not only can defend several outsider eavesdropper's attacks but also can remove the drawback of information leakage, which prevents the secret messages being leaked out to other people through the public information. In addition, our protocol is practical since the preparation and the measurement of single photon quantum states in both the polarization and the spatial-mode degrees of freedom are available with current quantum techniques.

  6. 90-degree polarization switching in BaTiO3 crystals without domain wall motion

    NASA Astrophysics Data System (ADS)

    Li, Y. W.; Scott, J. F.; Fang, D. N.; Li, F. X.

    2013-12-01

    We report 90° polarization switching in a BaTiO3 crystal without domain wall (DW) motion by prefabricating samples with interlocking domains via compression. During electric re-poling of the depoled and aged crystals, 90° domain nucleation still exists, but 90° DW motion is inhibited by the strong constraints from surrounding domains, leading to DW-free 90° polarization switching. The measured coercive field of 500 V/mm for the DW-free 90° switching is close to the intrinsic values and much larger than that of 80 V/mm via 90° DW motion. Compared to the rather difficult domain-free 180° polarization switching in ultrathin films, 90° DW-free switching is easier.

  7. Degrees of polarization of reflected light eliciting polarotaxis in dragonflies (Odonata), mayflies (Ephemeroptera) and tabanid flies (Tabanidae).

    PubMed

    Kriska, György; Bernáth, Balázs; Farkas, Róbert; Horváth, Gábor

    2009-12-01

    With few exceptions insects whose larvae develop in freshwater possess positive polarotaxis, i.e., are attracted to sources of horizontally polarized light, because they detect water by means of the horizontal polarization of light reflected from the water surface. These insects can be deceived by artificial surfaces (e.g. oil lakes, asphalt roads, black plastic sheets, dark-coloured cars, black gravestones, dark glass surfaces, solar panels) reflecting highly and horizontally polarized light. Apart from the surface characteristics, the extent of such a 'polarized light pollution' depends on the illumination conditions, direction of view, and the threshold p* of polarization sensitivity of a given aquatic insect species. p* means the minimum degree of linear polarization p of reflected light that can elicit positive polarotaxis from a given insect species. Earlier there were no quantitative data on p* in aquatic insects. The aim of this work is to provide such data. Using imaging polarimetry in the red, green and blue parts of the spectrum, in multiple-choice field experiments we measured the threshold p* of ventral polarization sensitivity in mayflies, dragonflies and tabanid flies, the positive polarotaxis of which has been shown earlier. In the blue (450nm) spectral range, for example, we obtained the following thresholds: dragonflies: Enallagma cyathigerum (0%

  8. Variation of optical characteristics of polarized laser radiation in dielectric upon its low-frequency rotation and heating

    NASA Astrophysics Data System (ADS)

    Gladyshev, V. O.; Portnov, D. I.; Sadovnikov, S. V.; Kauts, V. L.; Sharandin, E. A.

    2015-08-01

    The results of experiments in which coherent laser radiation with wavelength λ = 0.632991 µm experienced rotation of its plane of polarization, beam deviation, and change of intensity after propagating through an optical disk made of TF3 glass with refractive index n = 1.71250 and glued to a gyromotor, are discussed. The experiments were conducted at angle of incidence of the beam on a flat surface of the optical disk v = 60°. The rotational frequency of the disk was varied from 2 to 10 Hz for two directions of rotation. At low speed of rotation, the main factor causing mechanical deformations and, as a result, changes in optical characteristics of radiation propagated through the optical disk is heating of the metal—glass interface.

  9. Electric field induced critical points and polarization rotations in relaxor ferroelectrics

    NASA Astrophysics Data System (ADS)

    Kutnjak, Zdravko; Blinc, Robert; Ishibashi, Y.

    2007-09-01

    The giant electromechanical response in ferroelectric relaxors such as Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) is of great importance for a number of ultrasonic and medical applications as well as in telecommunications. On the basis of the dielectric, heat capacity, and piezoelectric investigations on PMN-PT crystals of various PT compositions and bias fields, we have recently shown the existence of a line of critical points for the paraelectric to ferroelectric transformations in the composition-temperature-electric field (x-T-E) phase diagram. Here, we show the piezobehavior in more detail and present a theoretical evaluation of the Widom line and the critical line. This line effectively terminates a surface of first order transitions. Above this line, supercritical evolution has been observed. On approaching the critical point, both the enthalpy cost to induce the intermediate monoclinic states and thus the barrier for polarization rotations decrease significantly. The maximum of the piezoelectric response is not at E=0 , but at the critical field values. It is shown that the critical fluctuations in the proximity of the critical points are directly responsible for the observed enhancement of the electromechanical response in the PMN-PT system. In view of the large electric field dependence of the dielectric constant near the critical point, these systems may also be important as electric field tunable elements.

  10. Absolute intensity and polarization of rotational Raman scattering from N2, O2, and CO2

    NASA Technical Reports Server (NTRS)

    Penney, C. M.; St.peters, R. L.; Lapp, M.

    1973-01-01

    An experimental examination of the absolute intensity, polarization, and relative line intensities of rotational Raman scattering (RRS) from N2, O2, and CO2 is reported. The absolute scattering intensity for N2 is characterized by its differential cross section for backscattering of incident light at 647.1 nm, which is calculated from basic measured values. The ratio of the corresponding cross section for O2 to that for N2 is 2.50 plus or minus 5 percent. The intensity recent for N2, O2, and CO2 are shown to compare favorably to values calculated from recent measurements of the depolarization of Rayleigh scattering plus RRS. Measured depolarizations of various RRS lines agree to within a few percent with the theoretical value of 3/4. Detailed error analyses are presented for intensity and depolarization measurements. Finally, extensive RRS spectra at nominal gas temperatures of 23 C, 75 C, and 125 C are presented and shown to compare favorably to theoretical predictions.

  11. All-optical quantization and coding scheme for ultrafast analog-to-digital conversion exploiting polarization switches based on nonlinear polarization rotation in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Wen, Huashun; Wang, Hongxiang; Ji, Yuefeng

    2012-08-01

    A novel all-optical quantization and coding scheme for ultrafast analog-to-digital (A/D) conversion exploiting polarization switches (PSWs) based on nonlinear polarization rotation (NPR) in semiconductor optical amplifiers (SOAs) is proposed. In addition, a theoretical model for the polarization switch based on NPR is presented. Through cascading two PSWs, a 2-period transfer function for 3-bit long all-optical quantization and coding is realized numerically for the first time to the authors' knowledge. The effective number of bits (ENOB), the limitation of bandwidth and conversion speed and the scalability are also investigated. The proposed all-optical quantization and coding scheme, combined with existing all-optical sampling techniques, will enable ultrafast A/D conversion at operating speed of hundreds of Gs/s with at least 3 bit resolution, and allows low optical power requirements, photonic integration, and easy scalability.

  12. Ultracompact and high efficient silicon-based polarization splitter-rotator using a partially-etched subwavelength grating coupler

    PubMed Central

    Xu, Yin; Xiao, Jinbiao

    2016-01-01

    On-chip polarization manipulation is pivotal for silicon-on-insulator material platform to realize polarization-transparent circuits and polarization-division-multiplexing transmissions, where polarization splitters and rotators are fundamental components. In this work, we propose an ultracompact and high efficient silicon-based polarization splitter-rotator (PSR) using a partially-etched subwavelength grating (SWG) coupler. The proposed PSR consists of a taper-integrated SWG coupler combined with a partially-etched waveguide between the input and output strip waveguides to make the input transverse-electric (TE) mode couple and convert to the output transverse-magnetic (TM) mode at the cross port while the input TM mode confine well in the strip waveguide during propagation and directly output from the bar port with nearly neglected coupling. Moreover, to better separate input polarizations, an additional tapered waveguide extended from the partially-etched waveguide is also added. From results, an ultracompact PSR of only 8.2 μm in length is achieved, which is so far the reported shortest one. The polarization conversion loss and efficiency are 0.12 dB and 98.52%, respectively, together with the crosstalk and reflection loss of −31.41/−22.43 dB and −34.74/−33.13 dB for input TE/TM mode at wavelength of 1.55 μm. These attributes make the present device suitable for constructing on-chip compact photonic integrated circuits with polarization-independence. PMID:27306112

  13. Ultracompact and high efficient silicon-based polarization splitter-rotator using a partially-etched subwavelength grating coupler

    NASA Astrophysics Data System (ADS)

    Xu, Yin; Xiao, Jinbiao

    2016-06-01

    On-chip polarization manipulation is pivotal for silicon-on-insulator material platform to realize polarization-transparent circuits and polarization-division-multiplexing transmissions, where polarization splitters and rotators are fundamental components. In this work, we propose an ultracompact and high efficient silicon-based polarization splitter-rotator (PSR) using a partially-etched subwavelength grating (SWG) coupler. The proposed PSR consists of a taper-integrated SWG coupler combined with a partially-etched waveguide between the input and output strip waveguides to make the input transverse-electric (TE) mode couple and convert to the output transverse-magnetic (TM) mode at the cross port while the input TM mode confine well in the strip waveguide during propagation and directly output from the bar port with nearly neglected coupling. Moreover, to better separate input polarizations, an additional tapered waveguide extended from the partially-etched waveguide is also added. From results, an ultracompact PSR of only 8.2 μm in length is achieved, which is so far the reported shortest one. The polarization conversion loss and efficiency are 0.12 dB and 98.52%, respectively, together with the crosstalk and reflection loss of ‑31.41/‑22.43 dB and ‑34.74/‑33.13 dB for input TE/TM mode at wavelength of 1.55 μm. These attributes make the present device suitable for constructing on-chip compact photonic integrated circuits with polarization-independence.

  14. Ultracompact and high efficient silicon-based polarization splitter-rotator using a partially-etched subwavelength grating coupler.

    PubMed

    Xu, Yin; Xiao, Jinbiao

    2016-01-01

    On-chip polarization manipulation is pivotal for silicon-on-insulator material platform to realize polarization-transparent circuits and polarization-division-multiplexing transmissions, where polarization splitters and rotators are fundamental components. In this work, we propose an ultracompact and high efficient silicon-based polarization splitter-rotator (PSR) using a partially-etched subwavelength grating (SWG) coupler. The proposed PSR consists of a taper-integrated SWG coupler combined with a partially-etched waveguide between the input and output strip waveguides to make the input transverse-electric (TE) mode couple and convert to the output transverse-magnetic (TM) mode at the cross port while the input TM mode confine well in the strip waveguide during propagation and directly output from the bar port with nearly neglected coupling. Moreover, to better separate input polarizations, an additional tapered waveguide extended from the partially-etched waveguide is also added. From results, an ultracompact PSR of only 8.2 μm in length is achieved, which is so far the reported shortest one. The polarization conversion loss and efficiency are 0.12 dB and 98.52%, respectively, together with the crosstalk and reflection loss of -31.41/-22.43 dB and -34.74/-33.13 dB for input TE/TM mode at wavelength of 1.55 μm. These attributes make the present device suitable for constructing on-chip compact photonic integrated circuits with polarization-independence. PMID:27306112

  15. Polarized foreground removal at low radio frequencies using rotation measure synthesis: uncovering the signature of hydrogen reionization

    NASA Astrophysics Data System (ADS)

    Geil, Paul M.; Gaensler, B. M.; Wyithe, J. Stuart B.

    2011-11-01

    Measurement of redshifted 21-cm emission from neutral hydrogen promises to be the most effective method for studying the reionization history of hydrogen and, indirectly, the first galaxies. These studies will be limited not by raw sensitivity to the signal, but rather, by bright foreground radiation from Galactic and extragalactic radio sources and the Galactic continuum. In addition, leakage due to gain errors and non-ideal feeds conspire to further contaminate low-frequency radio observations. This leakage leads to a portion of the complex linear polarization signal finding its way into Stokes I, and inhibits the detection of the non-polarized cosmological signal from the epoch of reionization. In this work, we show that rotation measure synthesis can be used to recover the signature of cosmic hydrogen reionization in the presence of contamination by polarized foregrounds. To achieve this, we apply the rotation measure synthesis technique to the Stokes I component of a synthetic data cube containing Galactic foreground emission, the effect of instrumental polarization leakage and redshifted 21-cm emission by neutral hydrogen from the epoch of reionization. This produces an effective Stokes I Faraday dispersion function for each line of sight, from which instrumental polarization leakage can be fitted and subtracted. Our results show that it is possible to recover the signature of reionization in its late stages (z≈ 7) by way of the 21-cm power spectrum, as well as through tomographic imaging of ionized cavities in the intergalactic medium.

  16. Prediction of Heat and Mass Transfer in a Rotating Ribbed Coolant Passage With a 180 Degree Turn

    NASA Technical Reports Server (NTRS)

    Rigby, David L.

    1999-01-01

    Numerical results are presented for flow in a rotating internal passage with a 180 degree turn and ribbed walls. Reynolds numbers ranging from 5200 to 7900, and Rotation numbers of 0.0 and 0.24 were considered. The straight sections of the channel have a square cross section, with square ribs spaced one hydraulic diameter (D) apart on two opposite sides. The ribs have a height of 0.1D and are not staggered from one side to the other. The full three dimensional Reynolds Averaged Navier-Stokes equations are solved combined with the Wilcox k-omega turbulence model. By solving an additional equation for mass transfer, it is possible to isolate the effect of buoyancy in the presence of rotation. That is, heat transfer induced buoyancy effects can be eliminated as in naphthalene sublimation experiments. Heat transfer, mass transfer and flow field results are presented with favorable agreement with available experimental data. It is shown that numerically predicting the reattachment between ribs is essential to achieving an accurate prediction of heat/mass transfer. For the low Reynolds numbers considered, the standard turbulence model did not produce reattachment between ribs. By modifying the wall boundary condition on omega, the turbulent specific dissipation rate, much better agreement with the flow structure and heat/ mass transfer was achieved. It is beyond the scope of the present work to make a general recommendation on the omega wall boundary condition. However, the present results suggest that the omega boundary condition should take into account the proximity to abrupt changes in geometry.

  17. Controlled quantum secure communication protocol with single photons in both polarization and spatial-mode degrees of freedom

    NASA Astrophysics Data System (ADS)

    Wang, Lili; Ma, Wenping

    2016-02-01

    In this paper, we propose a new controlled quantum secure direct communication (CQSDC) protocol with single photons in both polarization and spatial-mode degrees of freedom. Based on the defined local collective unitary operations, the sender’s secret messages can be transmitted directly to the receiver through encoding secret messages on the particles. Only with the help of the third side, the receiver can reconstruct the secret messages. Each single photon in two degrees of freedom can carry two bits of information, so the cost of our protocol is less than others using entangled qubits. Moreover, the security of our QSDC network protocol is discussed comprehensively. It is shown that our new CQSDC protocol cannot only defend the outsider eavesdroppers’ several sorts of attacks but also the inside attacks. Besides, our protocol is feasible since the preparation and the measurement of single photon quantum states in both the polarization and the spatial-mode degrees of freedom are available with current quantum techniques.

  18. Rotation of Nuclei as Observed in Ternary Fission of the Reaction 235U(nth,f) Induced by Polarized Neutron

    NASA Astrophysics Data System (ADS)

    Gönnenwein, F.; Gagarski, A.; Guseva, I.; Petrov, G.; Sokolov, V.; Zavarukhkina, T.; Mutterer, M.; Nesvizhevski, V.; Bunakov, V.; Kadmensky, S.

    2007-05-01

    Ternary fission of the standard reaction 235U(nth,f) induced by cold polarized neutrons has been investigated. Fission fragments and light charged particles were recorded in coincidence. Following cold neutron capture the compound nucleus 236U* has spin 3- or 4-. At the saddle point of the fissioning 236U* nucleus these states are collective. They are expected to retain a sizable collectivity down to the scission point. In fact, a collective rotation has been sensed by the shift in the angular distribution of the light charged particles which depends on the orientation of neutron polarization. Direct observation of the rotation of 236U* excited in a cold neutron reaction is reported here for the first time. It is proposed to call the new phenomenon the "ROT-effect".

  19. Current-induced giant polarization rotation using a ZnO single crystal doped with nitrogen ions

    PubMed Central

    Tate, Naoya; Kawazoe, Tadashi; Nomura, Wataru; Ohtsu, Motoichi

    2015-01-01

    Giant polarization rotation in a ZnO single crystal was experimentally demonstrated based on a novel phenomenon occurring at the nanometric scale. The ZnO crystal was doped with N+ and N2+ ions serving as p-type dopants. By applying an in-plane current using a unique arrangement of electrodes on the device, current-induced polarization rotation of the incident light was observed. From the results of experimental demonstrations and discussions, it was verified that this novel behavior originates from a specific distribution of dopants and the corresponding light–matter interactions in a nanometric space, which are allowed by the existence of such a dopant distribution. PMID:26246456

  20. Rotation of X-ray polarization in the glitches of a silicon crystal monochromator

    PubMed Central

    Sutter, John P.; Boada, Roberto; Bowron, Daniel T.; Stepanov, Sergey A.; Díaz-Moreno, Sofía

    2016-01-01

    EXAFS studies on dilute samples are usually carried out by collecting the fluorescence yield using a large-area multi-element detector. This method is susceptible to the ‘glitches’ produced by all single-crystal monochromators. Glitches are sharp dips or spikes in the diffracted intensity at specific crystal orientations. If incorrectly compensated, they degrade the spectroscopic data. Normalization of the fluorescence signal by the incident flux alone is sometimes insufficient to compensate for the glitches. Measurements performed at the state-of-the-art wiggler beamline I20-scanning at Diamond Light Source have shown that the glitches alter the spatial distribution of the sample’s quasi-elastic X-ray scattering. Because glitches result from additional Bragg reflections, multiple-beam dynamical diffraction theory is necessary to understand their effects. Here, the glitches of the Si(111) four-bounce monochromator of I20-scanning just above the Ni K edge are associated with their Bragg reflections. A fitting procedure that treats coherent and Compton scattering is developed and applied to a sample of an extremely dilute (100 micromolal) aqueous solution of Ni(NO3)2. The depolarization of the wiggler X-ray beam out of the electron orbit is modeled. The fits achieve good agreement with the sample’s quasi-elastic scattering with just a few parameters. The X-ray polarization is rotated up to ±4.3° within the glitches, as predicted by dynamical diffraction. These results will help users normalize EXAFS data at glitches. PMID:27504076

  1. Design of a compact and integrated TM-rotated/TE-through polarization beam splitter for silicon-based slot waveguides.

    PubMed

    Xu, Yin; Xiao, Jinbiao

    2016-01-20

    A compact and integrated TM-rotated/TE-through polarization beam splitter for silicon-based slot waveguides is proposed and characterized. For the input TM mode, it is first transferred into the cross strip waveguide using a tapered directional coupler (DC), and then efficiently rotated to the corresponding TE mode using an L-shaped bending polarization rotator (PR). Finally, the TE mode for slot waveguide at the output end is obtained with the help of a strip-to-slot mode converter. By contrast, for the input TE mode, it almost passes through the slot waveguide directly and outputs at the bar end with nearly neglected coupling due to a large mode mismatch. Moreover, an additional S-bend connecting the tapered DC and bending PR is used to enhance the performance. Results show that a total device length of 19.6 μm is achieved, where the crosstalk (CT) and polarization conversion loss are, respectively -26.09 and 0.54 dB, for the TM mode, and the CT and insertion loss are, respectively, -22.21 and 0.41 dB, for the TE mode, both at 1.55 μm. The optical bandwidth is approximately 50 nm with a CT<-20  dB. In addition, fabrication tolerances and field evolution are also presented. PMID:26835937

  2. Obtaining high degree of circular polarization at x-ray free electron lasers via a reverse undulator taper

    NASA Astrophysics Data System (ADS)

    Schneidmiller, E. A.; Yurkov, M. V.

    2013-11-01

    Baseline design of a typical x-ray free electron laser (FEL) undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at x-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade, one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress the powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of a nontapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering the SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft x-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced. The proposed method is rather universal, i.e., it can be used at SASE FELs and seeded (self-seeded) FELs, with any wavelength of interest, in a wide range of electron beam parameters, and with any repetition rate. It can be used at different x-ray FEL facilities, in particular at Linac Coherent Light Source after installation of the helical afterburner in the near future.

  3. Silicon waveguide polarization rotation Bragg grating with phase shift section and sampled grating scheme

    NASA Astrophysics Data System (ADS)

    Okayama, Hideaki; Onawa, Yosuke; Shimura, Daisuke; Yaegashi, Hiroki; Sasaki, Hironori

    2016-08-01

    We describe a Bragg grating with a phase shift section and a sampled grating scheme that converts input polarization to orthogonal polarization. A very narrow polarization-independent wavelength peak can be generated by phase shift structures and polarization-independent multiple diffraction peaks by sampled gratings. The characteristics of the device were examined by transfer matrix and finite-difference time-domain methods.

  4. Interlocked chiral/polar domain walls and large optical rotation in Ni{sub 3}TeO{sub 6}

    SciTech Connect

    Wang, Xueyun; Huang, Fei-Ting; Yang, Junjie; Oh, Yoon Seok; Cheong, Sang-Wook

    2015-07-01

    Chirality, i.e., handedness, pervades much of modern science from elementary particles, DNA-based biology to molecular chemistry; however, most of the chirality-relevant materials have been based on complex molecules. Here, we report inorganic single-crystalline Ni{sub 3}TeO{sub 6}, forming in a corundum-related R3 structure with both chirality and polarity. These chiral Ni{sub 3}TeO{sub 6} single crystals exhibit a large optical specific rotation (α)—1355° dm{sup −1} cm{sup 3} g{sup −1}. We demonstrate, for the first time, that in Ni{sub 3}TeO{sub 6}, chiral and polar domains form an intriguing domain pattern, resembling a radiation warning sign, which stems from interlocked chiral and polar domain walls through lowering of the wall energy.

  5. A dead-zone free ⁴He atomic magnetometer with intensity-modulated linearly polarized light and a liquid crystal polarization rotator.

    PubMed

    Wu, T; Peng, X; Lin, Z; Guo, H

    2015-10-01

    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. PMID:26520938

  6. Deterministic Polarization Entanglement Purification of χ-type entangled states in Multiple Degrees of Freedom

    NASA Astrophysics Data System (ADS)

    Shi, Ronghua; Liu, Shaorong; Wang, Shuo; Guo, Ying

    2015-02-01

    We present two deterministic entanglement purifications protocols for χ-type entangled states, resorting to multiple degrees of freedom. One protocol is implemented with the spatial entanglement to distill the maximally entangled states from the mixed states, resorting to some linear optical elements. Another one is implemented with the frequency entanglement for the purification. All the parties can jointly distill the maximally entangled states from the mixed states affected by the environmental noise during transmission. Both of the protocols can work in a deterministic way with the success probability 100 %, in principle. The derived features may make the protocols useful in the practical long-distance quantum communication.

  7. Rotational infrared polarization modulator using a MEMS-based air turbine with different types of journal bearing

    NASA Astrophysics Data System (ADS)

    Hara, Motoaki; Tanaka, Shuji; Esashi, Masayoshi

    2003-03-01

    This paper describes rotational infrared polarization modulators using a micro-electromechanical-system-based (MEMS-based) air turbine with different types of journal bearing. Three types of journal bearing, circular, symmetrical two-lobed and asymmetrical seven-lobed journal bearing, were compared. Using an optical displacement meter and a high speed camera, it was confirmed that all turbines exhibit three modes of rotation: (a) low speed mode, (b) intermediate mode and (c) high speed mode in this order, when decreasing N2 flow rate to an aerostatic thrust bearing. In the low speed mode, the rotor is lifted up by excess flow to the thrust bearing, making a contact with an upper layer. In the high speed mode, the rotor is levitated without any contact to the upper and lower layers by balanced flow to the thrust bearing, and the maximum rotational speed of 74000 rpm was achieved using the asymmetrical seven-lobed bearing. The rotation in this mode is, however, discontinuous due to the collision between the rotor and the journal bearing. It was concluded that a journal bearing with sufficient load capacity is necessary for continuous high speed rotation.

  8. BICEP3: a 95GHz refracting telescope for degree-scale CMB polarization

    NASA Astrophysics Data System (ADS)

    Ahmed, Z.; Amiri, M.; Benton, S. J.; Bock, J. J.; Bowens-Rubin, R.; Buder, I.; Bullock, E.; Connors, J.; Filippini, J. P.; Grayson, J. A.; Halpern, M.; Hilton, G. C.; Hristov, V. V.; Hui, H.; Irwin, K. D.; Kang, J.; Karkare, K. S.; Karpel, E.; Kovac, J. M.; Kuo, C. L.; Netterfield, C. B.; Nguyen, H. T.; O'Brient, R.; Ogburn, R. W.; Pryke, C.; Reintsema, C. D.; Richter, S.; Thompson, K. L.; Turner, A. D.; Vieregg, A. G.; Wu, W. L. K.; Yoon, K. W.

    2014-08-01

    Bicep3 is a 550 mm-aperture refracting telescope for polarimetry of radiation in the cosmic microwave background at 95 GHz. It adopts the methodology of Bicep1, Bicep2 and the Keck Array experiments | it possesses sufficient resolution to search for signatures of the inflation-induced cosmic gravitational-wave background while utilizing a compact design for ease of construction and to facilitate the characterization and mitigation of systematics. However, Bicep3 represents a significant breakthrough in per-receiver sensitivity, with a focal plane area 5x larger than a Bicep2/Keck Array receiver and faster optics (f=1:6 vs. f=2:4). Large-aperture infrared-reflective metal-mesh filters and infrared-absorptive cold alumina filters and lenses were developed and implemented for its optics. The camera consists of 1280 dual-polarization pixels; each is a pair of orthogonal antenna arrays coupled to transition-edge sensor bolometers and read out by multiplexed SQUIDs. Upon deployment at the South Pole during the 2014-15 season, Bicep3 will have survey speed comparable to Keck Array 150 GHz (2013), and will signifcantly enhance spectral separation of primordial B-mode power from that of possible galactic dust contamination in the Bicep2 observation patch

  9. Unidirectional cross polarization rotator with enhanced broadband transparency by cascading twisted nanobars

    NASA Astrophysics Data System (ADS)

    Wang, Ying-Hua; Shao, Jian; Li, Jie; Zhu, Ming-Jie; Li, Jiaqi; Dong, Zheng-Gao

    2016-05-01

    We demonstrate the optical activity for linear polarization by twisting cascading multilayer nanobars, for which the x- (y-)polarized light is significantly transformed to a y- (x-)polarized one with enhanced transmittance in a unidirectional manner, and the bandwidth can be broadened by increasing the cascading number of layers. The polarization conversion rate reaches nearly 100% with a maximum cross-polarization transmission coefficient larger than 0.95. This phenomenon is attributed to the chiral structural arrangement and anisotropic resonance of nanobars, which consequently leads to different cross-polarization conversions between forward and backward incident lights, and thus the unidirectional transmission with an extinction ratio up to 103. These characteristics show application potential in optical nano-devices.

  10. A two degree of freedom micro-gripper with grasping and rotating functions for optical fibers assembling.

    PubMed

    Chen, Weihai; Shi, Xiaohui; Chen, Wenjie; Zhang, Jianbin

    2013-11-01

    In this paper, a two degree of freedom flexure-based micro-gripper is proposed and applied in the complicated assembling process of optical fibers. The design concept is modeled on the manipulation of human fingers. Therefore, the two tips of micro-gripper, just like human fingers, can easily grasp the optical fiber with a controllable force and precisely rotate it by the rubbing operation. In addition, some sensors installed on the micro-gripper can enhance the operating accuracy. In the developing process, pseudo-rigid-body model method and virtual work principle are employed to conduct theoretical design. Then the obtained theoretical model is validated and optimized by the finite element analysis. Fabrication of the micro-gripper adopts wire electro discharge machining technology and material of aluminum alloy (AL-7075). Experimental studies are carried out on the prototype to further validate the performance of micro-gripper. Experimental results indicate that the developed micro-gripper can well satisfy the requirements of our mission, which also means that it can be widely used in micro-manipulation field. PMID:24289441