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Sample records for birefringence pvlas achievements

  1. The PVLAS experiment: detecting vacuum magnetic birefringence

    NASA Astrophysics Data System (ADS)

    Zavattini, G.; Della Valle, F.; Gastaldi, U.; Messineo, G.; Milotti, E.; Pengo, R.; Piemontese, L.; Ruoso, G.

    2013-06-01

    The PVLAS collaboration is presently assembling a new apparatus to detect vacuum magnetic birefringence. This property is related to the structure of the QED vacuum and is predicted by the Euler-Heisenberg-Weisskopf effective Lagrangian. It can be detected by measuring the ellipticity acquired by a linearly polarised light beam propagating through a strong magnetic field. Here we report results of a scaled-down test setup and briefly describe the new PVLAS apparatus. This latter one is in construction and is based on a high-sensitivity ellipsometer with a high-finesse Fabry-Perot cavity (> 4×105) and two 0.8 m long 2.5 T rotating permanent dipole magnets. Measurements with the test setup have improved by a factor 2 the previous upper bound on the parameter Ae, which determines the strength of the nonlinear terms in the QED Lagrangian: Ae(PVLAS) < 3.3 × 10-21 T-2 95% c.l.

  2. Measurements of vacuum magnetic birefringence using permanent dipole magnets: the PVLAS experiment

    NASA Astrophysics Data System (ADS)

    Della Valle, F.; Gastaldi, U.; Messineo, G.; Milotti, E.; Pengo, R.; Piemontese, L.; Ruoso, G.; Zavattini, G.

    2013-05-01

    The PVLAS collaboration is presently assembling a new apparatus (at the INFN section of Ferrara, Italy) to detect vacuum magnetic birefringence (VMB). VMB is related to the structure of the quantum electrodynamics (QED) vacuum and is predicted by the Euler-Heisenberg-Weisskopf effective Lagrangian. It can be detected by measuring the ellipticity acquired by a linearly polarized light beam propagating through a strong magnetic field. Using the very same optical technique it is also possible to search for hypothetical low-mass particles interacting with two photons, such as axion-like (ALP) or millicharged particles. Here we report the results of a scaled-down test setup and describe the new PVLAS apparatus. This latter is in construction and is based on a high-sensitivity ellipsometer with a high-finesse Fabry-Perot cavity (>4 × 105) and two 0.8 m long 2.5 T rotating permanent dipole magnets. Measurements with the test setup have improved, by a factor 2, the previous upper bound on the parameter Ae, which determines the strength of the nonlinear terms in the QED Lagrangian: A(PVLAS)e < 3.3 × 10-21 T-2 at 95% c.l. Furthermore, new laboratory limits have been put on the inverse coupling constant of ALPs to two photons and confirmation of previous limits on the fractional charge of millicharged particles is given.

  3. A simple structure of all circular-air-holes photonic crystal fiber for achieving high birefringence and low confinement loss

    SciTech Connect

    Chou Chau, Yuan-Fong Lim, Chee Ming; Yoong, Voo Nyuk; Syafi'ie Idris, Muhammad Nur

    2015-12-28

    We propose a simple structure of photonic crystal fibers (PCFs) with high birefringence and low confinement loss based on one rectangular centric ring of smaller circular air holes (CAHs) in the fiber core, and three rings of larger CAHs in the fiber cladding. This simple geometry (using all CAHs with two different air hole sizes) is capable of achieving a flexible control of the birefringence, B = 5.501 × 10{sup −3}, and ultra-low confinement loss, 7.30 × 10{sup −5 }dB/km, at an excitation wavelength of λ = 1550 nm. The birefringence value is ∼5.0 times greater than that obtained for conventional CAH PCF. This simple structure has the added advantage from the view point of easy fabrication, robustness, and cost. A full-vector finite element method combined with anisotropic perfectly matched layers was used to analyze the various fiber structures. We have analyzed four cases of CAH PCFs, focusing on the core asymmetry design as opposed to the conventional approach of CAHs or elliptical air holes on the cladding and core. The robustness against manufacturing inaccuracies of the proposed structure has also been further investigated in this work.

  4. A simple structure of all circular-air-holes photonic crystal fiber for achieving high birefringence and low confinement loss

    NASA Astrophysics Data System (ADS)

    Chou Chau, Yuan-Fong; Lim, Chee Ming; Yoong, Voo Nyuk; Syafi'ie Idris, Muhammad Nur

    2015-12-01

    We propose a simple structure of photonic crystal fibers (PCFs) with high birefringence and low confinement loss based on one rectangular centric ring of smaller circular air holes (CAHs) in the fiber core, and three rings of larger CAHs in the fiber cladding. This simple geometry (using all CAHs with two different air hole sizes) is capable of achieving a flexible control of the birefringence, B = 5.501 × 10-3, and ultra-low confinement loss, 7.30 × 10-5 dB/km, at an excitation wavelength of λ = 1550 nm. The birefringence value is ˜5.0 times greater than that obtained for conventional CAH PCF. This simple structure has the added advantage from the view point of easy fabrication, robustness, and cost. A full-vector finite element method combined with anisotropic perfectly matched layers was used to analyze the various fiber structures. We have analyzed four cases of CAH PCFs, focusing on the core asymmetry design as opposed to the conventional approach of CAHs or elliptical air holes on the cladding and core. The robustness against manufacturing inaccuracies of the proposed structure has also been further investigated in this work.

  5. Controlling birefringence in dielectrics

    NASA Astrophysics Data System (ADS)

    Danner, Aaron J.; Tyc, Tomáš; Leonhardt, Ulf

    2011-06-01

    Birefringence, from the very essence of the word itself, refers to the splitting of light rays into two parts. In natural birefringent materials, this splitting is a beautiful phenomenon, resulting in the perception of a double image. In optical metamaterials, birefringence is often an unwanted side effect of forcing a device designed through transformation optics to operate in dielectrics. One polarization is usually implemented in dielectrics, and the other is sacrificed. Here we show, with techniques beyond transformation optics, that this need not be the case, that both polarizations can be controlled to perform useful tasks in dielectrics, and that rays, at all incident angles, can even follow different trajectories through a device and emerge together as if the birefringence did not exist at all. A number of examples are shown, including a combination Maxwell fisheye/Luneburg lens that performs a useful task and is achievable with current fabrication materials.

  6. Transparent zero-birefringence copolymer and its optical properties.

    PubMed

    Iwata, S; Tsukahara, H; Nihei, E; Koike, Y

    1997-07-01

    Birefringence is caused by both orientation of polymer chains and photoelasticity. These birefringences were compensated by random copolymerization of negative birefringent methyl methacrylate and positive birefringent benzyl methacrylate, but orientational and photoelastic zero birefringences were achieved with quite different compositions of the copolymers. Note that the birefringence of the copolymer that occurred in the process of injection molding was almost completely eliminated with a composition for orientational zero birefringence. The orientational and photoelastic zero-birefringence copolymers possessed enough transparency as optical materials that the total scattering losses were 30.4 and 19.5 dB/km, respectively, competing with the transparency of homopolymers. PMID:18259249

  7. Highly birefringent optical microfibers.

    PubMed

    Xuan, Haifeng; Ju, Jian; Jin, Wei

    2010-02-15

    Highly birefringent (Hi-Bi) air-clad silica microfibers (MFs) with wavelength and sub-wavelength scale transverse dimensions are studied theoretically and experimentally. Hi-Bi MFs are taper-drawn from the standard SMF-28 single mode fibers that are "pre-processed" by "cutting away" parts of the silica cladding on opposite sides of the fiber with a femtosecond infrared laser. Such Hi-Bi MFs have approximately elliptical cross-sections and are approximated by a three-layer model comprising a small central Ge-doped region surrounded by an elliptical silica region and an air-cladding. Theoretical modeling shows that phase and group birefringence of the order 10(-2) can be achieved with such air-clad Hi-Bi MFs. Experiments with an air-clad elliptical fiber with a major diameter of 0.9 microm and a minor/major diameter ratio of 0.9 demonstrated a group birefringence of approximately 0.015, agreeing well with the theoretical predictions. The Hi-Bi MFs are useful for micron/nanoscale polarization maintaining transmission and phase-sensitive interferometric sensors. PMID:20389393

  8. Coherent control of optically induced birefringence in azoaromatic molecules

    SciTech Connect

    Mendonca, C. R.; Neves, U. M.; Guedes, I.; Zilio, S. C.; Misoguti, L.

    2006-08-15

    Here we present the coherent control of two-photon induced birefringence in polymeric films containing Disperse Red 13 (DR13) azoaromatic molecules. Such control is achieved by enhancing and reducing the azochromophor cis-trans photoisomerization rate, which leads to the molecular orientation, inducing the birefringence. The dependence on chirp and phase mask of the birefringence signal was studied and modeled.

  9. New PVLAS results and limits on magnetically induced optical rotation and ellipticity in vacuum

    SciTech Connect

    Zavattini, E.; Raiteri, G.; Milotti, E.; Lozza, V.; Karuza, M.; Della Valle, F.; Cantatore, G.; Bregant, M.; Zavattini, G.; Di Domenico, G.; Ruoso, G.; Gastaldi, U.; Polacco, E.; Carusotto, S.; Cimino, R.

    2008-02-01

    In 2006 the PVLAS collaboration reported the observation of an optical rotation generated in vacuum by a magnetic field. To further check against possible instrumental artifacts, several upgrades to the PVLAS apparatus have been made during the past year. Two data taking runs, at the wavelength of 1064 nm, have been performed in the new configuration with magnetic field strengths of 2.3 and 5 T. The 2.3 T field value was chosen in order to avoid stray fields. The new observations do not show the presence of a rotation signal down to the levels of 1.2x10{sup -8} rad at 5 T and 1.0x10{sup -8} rad at 2.3 T (at 95% C.L.) with 45 000 passes in the magnetic field zone. In the same conditions no ellipticity signal was detected down to 1.4x10{sup -8} at 2.3 T (at 95% C.L.), whereas at 5 T a signal is still present. The physical nature of this ellipticity as due to an effect depending on B{sup 2} can be excluded by the measurement at 2.3 T. These new results completely exclude the previously published magnetically induced vacuum dichroism results, indicating that they were instrumental artifacts. These new results therefore also exclude the particle interpretation of the previous PVLAS results as due to a spin-zero boson. The background ellipticity at 2.3 T can be used to determine a new limit on the total photon-photon scattering cross section of {sigma}{sub {gamma}}{sub {gamma}}<4.5x10{sup -34} barn at 95% C.L.

  10. PVLAS experiment, star cooling and big bang nucleosynthesis constraints: Possible interpretation with temperature dependent gauge symmetry breaking

    SciTech Connect

    Kim, Jihn E.

    2007-09-01

    It is known that the kinetic mixing of a photon and another U(1){sub ex} gauge boson can introduce millicharged particles. Millicharged particles f of mass 0.1 eV can explain the PVLAS experiment. I suggest a temperature dependent gauge symmetry breaking of U(1){sub ex} for this idea to be consistent with astrophysical and cosmological constraints.

  11. Negative birefringent polyimide films

    NASA Technical Reports Server (NTRS)

    Harris, Frank W. (Inventor); Cheng, Stephen Z. D. (Inventor)

    1994-01-01

    A negative birefringent film, useful in liquid crystal displays, and a method for controlling the negative birefringence of a polyimide film is disclosed which allows the matching of an application to a targeted amount of birefringence by controlling the degree of in-plane orientation of the polyimide by the selection of functional groups within both the diamine and dianhydride segments of the polyimide which affect the polyimide backbone chain rigidity, linearity, and symmetry. The higher the rigidity, linearity and symmetry of the polyimide backbone, the larger the value of the negative birefringence of the polyimide film.

  12. Birefringence measurement of the cellophane film

    NASA Astrophysics Data System (ADS)

    Juárez-Ramírez, Julio César; Ortiz-Gutiérrez, Mauricio; Salgado-Verduzco, Marco Antonio; Pérez-Cortés, Mario; Olivares-Pérez, Arturo; Ordoñez-Padilla, Manuel Jorge; Ibarra-Torres, Juan Carlos

    2014-02-01

    In this work we describe an experimental technique to measure the birefringence of the cellophane film that has good behavior as half wave retarder. This technique is achieved when the film is placed in a polariscope that consists of a light source and properly arranged polarizing elements and a system of fringes is observed. Using Jones formalism for the system the birefringence appears in the phase term of harmonic functions. Some experimental results are shown.

  13. Birefringent filter design by use of a modified genetic algorithm.

    PubMed

    Wen, Mengtao; Yao, Jianping

    2006-06-10

    A modified genetic algorithm is proposed for the optimization of fiber birefringent filters. The orientation angles and the element lengths are determined by the genetic algorithm to minimize the sidelobe levels of the filters. Being different from the normal genetic algorithm, the algorithm proposed reduces the problem space of the birefringent filter design to achieve faster speed and better performance. The design of 4-, 8-, and 14-section birefringent filters with an improved sidelobe suppression ratio is realized. A 4-section birefringent filter designed with the algorithm is experimentally realized. PMID:16761031

  14. Phase and birefringence aberration correction

    DOEpatents

    Bowers, M.; Hankla, A.

    1996-07-09

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90{degree} such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system. 5 figs.

  15. Phase and birefringence aberration correction

    DOEpatents

    Bowers, Mark; Hankla, Allen

    1996-01-01

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90.degree. such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system.

  16. Dual function microscope for quantitative DIC and birefringence imaging

    NASA Astrophysics Data System (ADS)

    Li, Chengshuai; Zhu, Yizheng

    2016-03-01

    A spectral multiplexing interferometry (SXI) method is presented for integrated birefringence and phase gradient measurement on label-free biological specimens. With SXI, the retardation and orientation of sample birefringence are simultaneously encoded onto two separate spectral carrier waves, generated by a crystal retarder oriented at a specific angle. Thus sufficient information for birefringence determination can be obtained from a single interference spectrum, eliminating the need for multiple acquisitions with mechanical rotation or electrical modulation. In addition, with the insertion of a Nomarski prism, the setup can then acquire quantitative differential interference contrast images. Red blood cells infected by malaria parasites are imaged for birefringence retardation as well as phase gradient. The results demonstrate that the SXI approach can achieve both quantitative phase imaging and birefringence imaging with a single, high-sensitivity system.

  17. Birefringence determination in turbid media.

    PubMed

    Baravian, Christophe; Dillet, Jérôme; Decruppe, Jean-Paul

    2007-03-01

    We study the influence of birefringence on incoherent polarized light transport in turbid media. In particular, Mueller matrices backscattered by a diffusing medium are modified by the birefringence of the suspending phase. We study this effect both theoretically, through Monte Carlo simulations, and experimentally with a highly birefringent xanthane solution in which particles are added at various concentrations to modify its turbidity. Comparisons between experiments on flow-induced birefringence of the xanthane solution with or without particles are in good agreement and show the capability of measuring birefringence in turbid media through analysis of Mueller matrices. PMID:17500742

  18. Birefringence determination in turbid media

    NASA Astrophysics Data System (ADS)

    Baravian, Christophe; Dillet, Jérôme; Decruppe, Jean-Paul

    2007-03-01

    We study the influence of birefringence on incoherent polarized light transport in turbid media. In particular, Mueller matrices backscattered by a diffusing medium are modified by the birefringence of the suspending phase. We study this effect both theoretically, through Monte Carlo simulations, and experimentally with a highly birefringent xanthane solution in which particles are added at various concentrations to modify its turbidity. Comparisons between experiments on flow-induced birefringence of the xanthane solution with or without particles are in good agreement and show the capability of measuring birefringence in turbid media through analysis of Mueller matrices.

  19. Magnetic birefringence of minerals.

    PubMed

    Jennings, Barry R; Wilson, Stephen R; Ridler, Peter J

    2005-01-15

    The earliest reports of magnetically induced optical birefringence included data for liquids, magnetic fluids and colloidal suspensions. Recent work has shown that with relatively straightforward apparatus, when carefully designed and aligned, measurable effects can be recorded even for suspensions of relatively weak diamagnetic materials, including mineral particles. By recording the magnitude of the birefringence induced in magnetic fields of up to two Tesla, a method for the analysis of the magnetic and optical characteristics of these diamagnetic colloids is evidenced. The principles, apparatus and methodology involved are described and novel data reported for the minerals attapulgite, bentonite, hectorite, kaolinite, montmorillonite and vermiculite. Preliminary experiments using pulsed fields on vermiculite sols show that, in favourable circumstances, estimates of particle size can be made by analysing signal response rates. PMID:15571692

  20. Holodiagrams in birefringent media.

    PubMed

    Rabal, Héctor; Cap, Nelly; Gottschalk, Karin V; Simon, María C

    2003-10-10

    The modifications to the holodiagram concept to describe free propagation (the extraordinary ray) inside birefringent materials are described. Holodiagrams are graphs showing the loci where the sum or the difference in the optical path from a generic point to two foci is the same. The holodiagrams obtained in this way give the shape of the surfaces that satisfy Fermat's principle, conjugate by reflection of one focus into the other, and represent the interference fringes obtained if both points are coherent sources. The reflection law in birefringent media is investigated in relation to this diagram. One direction for the optical axis is considered: parallel to the line joining the source and the observation point. Quartz-type and calcite-type crystals are studied. PMID:14577535

  1. Birefringent phononic structures

    SciTech Connect

    Psarobas, I. E. Exarchos, D. A.; Matikas, T. E.

    2014-12-15

    Within the framework of elastic anisotropy, caused in a phononic crystal due to low crystallographic symmetry, we adopt a model structure, already introduced in the case of photonic metamaterials, and by analogy, we study the effect of birefringence and acoustical activity in a phononic crystal. In particular, we investigate its low-frequency behavior and comment on the factors which determine chirality by reference to this model.

  2. Multichannel birefringent filter

    NASA Technical Reports Server (NTRS)

    Gouxiang, A.; Huefeng, H.

    1985-01-01

    A birefringent filter with a large field of view and no additional polarization is discussed. It plays an important role in observing the solar monochromatic image and the solar vector magnetic field. It has only one channel. For simultaneous multichannel observations, the solar spectrograph is better than the birefringent filter. A suggestion was proposed to try to obtain a multichannel birefringent filter which will be used in a new telescope at the Huairou reservoir station of Beijing Observatory. By means of N polarizing beam splitters, (N+1) channels can be divided. In principle, any number of limitless channels can be obtained, thereby subdividing the whole solar spectrum. But since the space in a telescope is limited, the channels to be used are also limited. For the new telescope, 5 and 9 channels are being considered, and the spectral range is from lambda 3800A to lambda 7000A. Many lines are included in this range, for example, H, K, H beta, lambda lambda 5324A, 5250A, 6302A, H alpha, etc., and some of the lines are suited to measure solar velocity fields. According to the character of these lines, the half width of each channel is determined. Moreover, in some channels the solid polarizing Michelson interferometer is considered for measuring velocity field with a lm/s accuracy. The advantages of the filter and problems to be solved are listed.

  3. Optical birefringence of aorta tissues

    NASA Astrophysics Data System (ADS)

    Tang, G. C.; Wang, W. B.; Pu, Y.; Alfano, R. R.

    2010-02-01

    The optical birefringence of porcine aortic tissues including heated and non-heated tissues was studied using polarization technique. The measurements show that a whole piece of aortic tissue has birefringence properties like a uniaxial crystal. The experiment results indicate that the birefringence status of tissue have a potential application for monitoring changes of tissue structure due to burning, plastic surgery, laser tissue welding and wound healing.

  4. Tunable optofluidic birefringent lens.

    PubMed

    Wee, D; Hwang, S H; Song, Y S; Youn, J R

    2016-05-01

    An optofluidic birefringent lens is demonstrated using hydrodynamic liquid-liquid (L(2)) interfaces in a microchannel. The L(2) lens comprises a nematic liquid crystal (NLC) phase and an optically isotropic phase for the main stream and the surrounding sub-stream, respectively. When the optofluidic device is subjected to a sufficiently strong electric field perpendicular to the flow direction, NLCs are allowed to orient along the external field rather than the flow direction overcoming fluidic viscous stress. The characteristics of the optofluidic birefringence lens are investigated by experimental and numerical analyses. The difference between the refractive indices of the main stream and the sub-stream changes according to the polarization direction of incident light, which determines the optical behaviour of the lens. The incidence of s-polarized light leads to a short focal point, while p-polarized light has a relatively long focal distance from the same L(2) interface. The curvatures and focal lengths of the lens are successfully evaluated by a hydrodynamic theory of NLCs and a simple ray-tracing model. PMID:27035877

  5. Birefringence insensitive optical coherence domain reflectometry system

    DOEpatents

    Everett, Matthew J.; Davis, Joseph G.

    2002-01-01

    A birefringence insensitive fiber optic optical coherence domain reflectometry (OCDR) system is provided containing non-polarization maintaining (non-PM) fiber in the sample arm and the reference arm without suffering from signal degradation caused by birefringence. The use of non-PM fiber significantly reduces the cost of the OCDR system and provides a disposable or multiplexed section of the sample arm. The dispersion in the reference arm and sample arm of the OCDR system are matched to achieve high resolution imaging. This system is useful in medical applications or for non-medical in situ probes. The disposable section of non-PM fiber in the sample arm can be conveniently replaced when contaminated by a sample or a patient.

  6. Circular birefringence of banded spherulites.

    PubMed

    Cui, Xiaoyan; Shtukenberg, Alexander G; Freudenthal, John; Nichols, Shane; Kahr, Bart

    2014-04-01

    Crystal optical properties of banded spherulites of 21 different compounds--molecular crystals, polymers, and minerals--with helically twisted fibers were analyzed with Mueller matrix polarimetry. The well-established radial oscillations in linear birefringence of many polycrystalline ensembles is accompanied by oscillations in circular birefringence that cannot be explained by the natural optical activity of corresponding compounds, some of which are centrosymmetric in the crystalline state. The circular birefringence is shown to be a consequence of misoriented, overlapping anisotropic lamellae, a kind of optical activity associated with the mesoscale stereochemistry of the refracting components. Lamellae splay as a consequence of space constraints related to simultaneous twisting of anisometric lamellae. This mechanism is supported by quantitative simulations of circular birefringence arising from crystallite twisting and splaying under confinement. PMID:24625095

  7. Birefringence measurements on crystalline silicon

    NASA Astrophysics Data System (ADS)

    Krüger, Christoph; Heinert, Daniel; Khalaidovski, Alexander; Steinlechner, Jessica; Nawrodt, Ronny; Schnabel, Roman; Lück, Harald

    2016-01-01

    Crystalline silicon has been proposed as a new test mass material in third generation gravitational wave detectors such as the Einstein telescope (ET). Birefringence can reduce the interferometric contrast and can produce dynamical disturbances in interferometers. In this work we use the method of polarization-dependent resonance-frequency analysis of Fabry-Perot-cavities containing silicon as a birefringent medium. Our measurements show a birefringence of silicon along the (111) axis of the order of {{Δ }} n≈ {10}-7 at a laser wavelength of 1550 nm and room temperature. A model is presented that explains the results of different settings of our measurements as a superposition of elastic strains caused by external stresses in the sample and plastic strains possibly generated during the production process. An application of our theory on the proposed ET test mass geometry suggests no critical effect on birefringence due to elastic strains.

  8. Birefringent corrugated waveguide

    DOEpatents

    Moeller, Charles P.

    1990-01-01

    A corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations, provides birefringence for rotation of polarization in the HE.sub.11 mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminum of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R.sub.0 from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R.sub.1 less than R.sub.0 at centers +b and -b from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric corrugations. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

  9. Birefringent corrugated waveguide

    SciTech Connect

    Moeller, C.P.

    1989-02-15

    A corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations, provides birefringence for rotation of polarization in the HE{sub 11} mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminium of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R{sub 0} from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R{sub 1} less than R{sub 0} at centers +b and {minus}b from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric waveguides. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

  10. Birefringent corrugated waveguide

    SciTech Connect

    Moeller, C.P.

    1990-03-06

    This patent describes a corrugated waveguide having a circular bore and noncircularly symmetric corrugations, and preferably elliptical corrugations which provides birefringence for rotation of polarization in the HE{sub 11} mode. The corrugated waveguide may be fabricated by cutting circular grooves on a lathe in a cylindrical tube or rod of aluminum of a diameter suitable for the bore of the waveguide, and then cutting an approximation to ellipses for the corrugations using a cutting radius R{sub 0} from the bore axis that is greater than the bore radius, and then making two circular cuts using a radius R{sub 1} less than R{sub 0} at centers + b and {minus} B from the axis of the waveguide bore. Alternatively, stock for the mandrel may be formed with an elliptical transverse cross section, and then only the circular grooves need be cut on a lathe, leaving elliptical corrugations between the grooves. In either case, the mandrel is first electroplated and then dissolved leaving a corrugated waveguide with noncircularly symmetric corrugations. A transition waveguide is used that gradually varies from circular to elliptical corrugations to couple a circularly corrugated waveguide to an elliptically corrugated waveguide.

  11. Synthesis of optical birefringent networks.

    NASA Technical Reports Server (NTRS)

    Ammann, E. O.

    1971-01-01

    Outline of synthesis procedures, with description of the birefringent networks which result from their use. Optical compensators are employed in synthesis procedures in two different ways. The first role is simply the practical one of compensating for slightly incorrect crystal lengths. The second role occurs because some synthesis procedures require different fractional retardations for the stages of the network. Lyot and Solc filters are described, and an attempt is made to show how birefringent networks function. Experimental results are presented, and the application of synthesis procedures to electrooptic networks is discussed.

  12. Fiber gyroscope with birefringence modulation

    NASA Astrophysics Data System (ADS)

    Carrara, S. L. A.; Kim, B. Y.; Shaw, H. J.

    1987-03-01

    A theoretical analysis of the nonreciprocal phase error in a highly-birefringent fiber gyroscope is presented, characterizing the different types of errors and their sources in a general form. These error terms are due to polarization cross coupling in the fiber and in the fiber components and can be reduced by modulating the magnitude of the fiber birefringence at appropriate locations in the optical circuit and by balancing the optical power between the two polarization eigenmodes of the fiber at the input of the interferometer. Experimental results demonstrating these techniques show a 20 dB relief on the performance requirements of the polarizer usually employed for drift reduction.

  13. Long range surface plasmons in birefringent media

    NASA Technical Reports Server (NTRS)

    Stegeman, G. I.

    1983-01-01

    The propagation properties of surface plasmon polaritons guided by thin metal films bounded by birefringent media are investigated. For the very thin (less than or equal to 150 A) films required to produce long propagation distances, the effects of birefringence on the dispersion relations are found to be minimal. A small effect of the birefringence on the mode attenuation is found.

  14. Birefringence characterization using transmission ellipsometry

    NASA Astrophysics Data System (ADS)

    Nee, Soe-Mie F.

    1992-12-01

    Birefringence can be obtained from the phase difference (Delta) between the ordinary and the extraordinary rays for normal transmission through a birefringent slab. Rotating analyzer ellipsometry (RAE) and null ellipsometry (NE) were used to measure (Delta) . NE gives accurate phase spectrum which shows linear dependence of phase on wave-number. The phase spectrum by RAE looks like a damped oscillatory curve. The calibration of RAE against NE shows that the extrema of RAE phase spectrum correspond to (Delta) equals m(pi) of NE spectrum, where m equals integer; the phases near m (pi) + (pi) /2 are about the same from both methods. Error caused by partially coherent interference of the multiple reflected waves within the slab consists basically of the sinusoidal functions of (Delta) and its harmonics, and is zero at (Delta) equals m(pi) . These errors can be suppressed by the least-square fit of m to a quadratic function of 1/(lambda) . The birefringence spectrum measured for a sapphire sample in the 0.4 to 0.9 micrometers wavelength region agrees with the handbook values.

  15. Simple method for locking birefringent resonators.

    PubMed

    Libson, Adam; Brown, Nicolas; Buikema, Aaron; López, Camilo Cela; Dordevic, Tamara; Heising, Matthew; Evans, Matthew

    2015-02-01

    We report on a simple method of locking a laser to a birefringent cavity using polarization spectroscopy. The birefringence of the resonator permits the simple extraction of an error signal by using one polarization state as a phase reference for another state. No modulation of the light or the resonator is required, reducing the complexity of the laser locking setup. This method of producing an error signal can be used on most birefringent optical resonators, even if the details of birefringence and eigenpolarizations are not known. This technique is particularly well suited for fiber ring resonators due to the inherent birefringence of the fiber and the unknown nature of that birefringence. We present an experimental demonstration of this technique using a fiber ring. PMID:25836232

  16. Control and design of fiber birefringence characteristics based on selective-filled hybrid photonic crystal fibers.

    PubMed

    Han, Tingting; Liu, Yan-Ge; Wang, Zhi; Guo, Junqi; Wu, Zhifang; Luo, Mingming; Li, Shuo; Wang, Jing; Wang, Wei

    2014-06-16

    We demonstrated a kind of birefringence-controllable hybrid photonic crystal fibers (HPCFs) by selectively infiltrating air holes of PCFs with index-tunable liquids processing higher index than silica background. Detailed theoretical investigations on mode couplings from fundamental core mode to high-index-liquid-rod modes and birefringence properties of several HPCFs were presented. Strong wavelength dependence of phase and group birefringence was found, and HPCFs with different arrangements of high index liquid rods possess distinct birefringence characteristics. Then, the Sagnac interferometers (SIs) based on two typical HPCFs with different liquid-rod arrangements were theoretically and experimentally studied. The results indicated the SIs exhibit different transmission spectra and temperature responses due to the distinct birefringence features of HPCFs. A temperature sensitivity of -45.8 nm/°C at 56.5 °C was achieved using one HPCF, and a sensitivity of -11.6 nm/°C from 65 °C to 85 °C was achieved using the other HPCF. The thermal tunable HPCFs with birefringence-controllable properties will provide great potential for a variety of tunable optical devices and sensors. PMID:24977594

  17. Hydrostatic Pressure Sensing with High Birefringence Photonic Crystal Fibers

    PubMed Central

    Fávero, Fernando C.; Quintero, Sully M. M.; Martelli, Cicero; Braga, Arthur M.B.; Silva, Vinícius V.; Carvalho, Isabel C. S.; Llerena, Roberth W. A.; Valente, Luiz C. G.

    2010-01-01

    The effect of hydrostatic pressure on the waveguiding properties of high birefringence photonic crystal fibers (HiBi PCF) is evaluated both numerically and experimentally. A fiber design presenting form birefringence induced by two enlarged holes in the innermost ring defining the fiber core is investigated. Numerical results show that modal sensitivity to the applied pressure depends on the diameters of the holes, and can be tailored by independently varying the sizes of the large or small holes. Numerical and experimental results are compared showing excellent agreement. A hydrostatic pressure sensor is proposed and demonstrated using an in-fiber modal interferometer where the two orthogonally polarized modes of a HiBi PCF generate fringes over the optical spectrum of a broad band source. From the analysis of experimental results, it is concluded that, in principle, an operating limit of 92 MPa in pressure could be achieved with 0.0003% of full scale resolution. PMID:22163435

  18. Constraints on cosmological birefringence energy dependence from CMB polarization data

    SciTech Connect

    Gubitosi, G.; Paci, F. E-mail: fpaci@sissa.it

    2013-02-01

    We study the possibility of constraining the energy dependence of cosmological birefringence by using CMB polarization data. We consider four possible behaviors, characteristic of different theoretical scenarios: energy-independent birefringence motivated by Chern-Simons interactions of the electromagnetic field, linear energy dependence motivated by a 'Weyl' interaction of the electromagnetic field, quadratic energy dependence, motivated by quantum gravity modifications of low-energy electrodynamics, and inverse quadratic dependence, motivated by Faraday rotation generated by primordial magnetic fields. We constrain the parameters associated to each kind of dependence and use our results to give constraints on the models mentioned. We forecast the sensitivity that Planck data will be able to achieve in this respect.

  19. Glue-induced birefringence in surface-attached FBG strain sensors

    NASA Astrophysics Data System (ADS)

    Helminger, Dominik; Daitche, Alexej; Roths, Johannes

    2014-05-01

    The influence of the gluing process on the birefringence of surface-glued FBGs that were inscribed in highly birefringence (HiBi) optical fibers of type Panda was studied by monitoring the variation of the birefringence during the gluing procedure. The isothermal curing process at 100°C of the epoxy-based adhesive is characterized by the reduction of birefringence during curing. Significant transversal strain is introduced into the fiber during the cool down period, which is due to different thermal expansion coefficients of the silica and the glue. When the slow axis of the HiBi fiber is oriented parallel to the surface, the glue-induced transversal strain reduces the birefringence of the fiber by ΔB = -6.6 10-5 and when it is perpendicular to the surface, it is increased by ΔB = 1.1 10-5. It can be estimated that for conventional FBGs in single mode fibers a glue-induced birefringence in the order of ΔB = 3.4 10-5 can be expected, which has to be taken into account if in surface-mounted FBG-based strain measurements a high accuracy has to be achieved.

  20. Birefringence in time-dependent moving media

    NASA Astrophysics Data System (ADS)

    Lin, Shirong; Zhang, Ruoyang; Zhai, Yanwang; Wei, Jianye; Zhao, Qing

    2016-08-01

    Electromagnetic wave propagation in one- and two-dimensional time-dependent moving media is investigated in this paper. We identify another origin of linear birefringence caused by the component of the flow perpendicular to the wave vector. Previously, birefringence is induced by applying external electric and magnetic fields to non-crystalline material. Here it is shown that the time-varying velocity field also contributes to such a phenomenon. Our results indicate that the parallel component, time-dependent or not, will not yield birefringence. Furthermore, the time-dependent flow also results in a frequency shift. One-dimensional simulation is conducted to demonstrate these effects.

  1. Optical temperature sensor utilizing birefringent crystals

    NASA Technical Reports Server (NTRS)

    Quick, William H. (Inventor); James, Kenneth A. (Inventor); Strahan, Virgil H. (Inventor)

    1980-01-01

    A temperature sensor comprising an optical transducer member having an array of birefringent crystals. The length and, accordingly, the sensitivity to temperature change of successive birefringent crystals varies according to a particular relationship. The transducer is interconnected with a fiber optic transmission and detecting system. Respective optical output signals that are transmitted from the birefringent crystals via the fiber optic transmission system are detected and decoded so as to correspond to digits of a numbering system, whereby an accurate digital representation of temperature can ultimately be provided.

  2. Spectral contents readout of birefringent sensor

    NASA Technical Reports Server (NTRS)

    Redner, Alex S.

    1989-01-01

    The technical objective of this research program was to develop a birefringent sensor, capable of measuring strain/stress up to 2000 F and a readout system based on Spectral Contents analysis. As a result of the research work, a data acquisition system was developed, capable of measuring strain birefringence in a sensor at 2000 F, with multi-point static and dynamic capabilities. The system uses a dedicated spectral analyzer for evaluation of stress-birefringence and a PC-based readout. Several sensor methods were evaluated. Fused silica was found most satisfactory. In the final evaluation, measurements were performed up to 2000 F and the system performance exceeded expectations.

  3. Measurement of 2D birefringence distribution

    NASA Astrophysics Data System (ADS)

    Noguchi, Masato; Ishikawa, Tsuyoshi; Ohno, Masahiro; Tachihara, Satoru

    1992-10-01

    A new measuring method of 2-D birefringence distribution has been developed. It has not been an easy job to get a birefringence distribution in an optical element with conventional ellipsometry because of its lack of scanning means. Finding an analogy between the rotating analyzer method in ellipsometry and the phase-shifting method in recently developed digital interferometry, we have applied the phase-shifting algorithm to ellipsometry, and have developed a new method that makes the measurement of 2-D birefringence distribution easy and possible. The system contains few moving parts, assuring reliability, and measures a large area of a sample at one time, making the measuring time very short.

  4. Photon pair generation in birefringent optical fibers

    NASA Astrophysics Data System (ADS)

    Smith, Brian J.; Mahou, P.; Cohen, Offir; Lundeen, J. S.; Walmsley, I. A.

    2009-12-01

    We study both experimentally and theoretically the generation of photon pairs by spontaneous four-wave mixing (SFWM) in standard birefringent optical fibers. The ability to produce a range of two-photon spectral states, from highly correlated (entangled) to completely factorable, by means of cross-polarized birefringent phase matching, is explored. A simple model is developed to predict the spectral state of the photon pair which shows how this can be adjusted by choosing the appropriate pump bandwidth, fiber length and birefringence. Spontaneous Raman scattering is modeled to determine the tradeoff between SFWM and background Raman noise, and the predicted results are shown to agree with experimental data.

  5. Spun optical fibres: A helical structure of linear birefringence or circular birefringence?

    SciTech Connect

    Morshnev, Sergey K; Gubin, Vladimir P; Vorob'ev, I P; Starostin, I I; Sazonov, Aleksandr I; Chamorovsky, Yury K; Korotkov, N M

    2009-03-31

    An experiment has been proposed, theoretically substantiated and accomplished which has provided conclusive evidence in favour of one of two models for the behaviour of polarised light in optical fibres fabricated by spinning preforms with a high built-in linear birefringence (spun fibres): a helical structure of the built-in linear birefringence axes and circular birefringence. The experiment, carried out with a reflective fibreoptic dual-polarisation interferometer, has shown that the behaviour of polarisation states in spun fibres can be understood in terms of a helical structure of the built-in linear birefringence axes. (optical fibres)

  6. Spectral contents readout of birefringent sensors

    NASA Technical Reports Server (NTRS)

    Redner, Alex S.; Voloshin, Arkady S.

    1988-01-01

    The objective of the research performed was to establish the feasibility of using spectral contents analysis to measure accurately, strains and retardation in birefringent sensors, and more generally, on transparent materials.

  7. Shock Induced Birefringence in Lithium Fluoride

    SciTech Connect

    Holmes, N C

    2001-06-01

    We have used an ellipsometer to measure the birefringence of lithium fluoride in shock compression experiments. In previous x-ray diffraction experiments, single crystal [100] LiF has been reported to remain cubic at moderate pressures.

  8. Birefringence, the Lost and Forgotten Optical Property

    NASA Astrophysics Data System (ADS)

    Nicholls, J.

    2009-05-01

    Petrologists and mineralogists could more effectively exploit birefringence and its derivative properties, retardation and interference color, to characterize minerals in thin section. Mineralogy texts and courses largely confine their treatments to the principal birefringences: γ - α, β - α, and γ - β in biaxial crystals and |ɛ - ω| in uniaxial crystals. Each section through a biaxial or uniaxial crystal has a birefringence and the birefringences range from zero to a maximum value for the substance under examination. The distribution of birefringence values on the indicatrix is not random; rather it follows a regular pattern. The pattern reveals itself in stereographic projection and it can be quantitatively depicted if the principal refractive indices are known. This pattern, when combined with the optical orientation of the crystal, places limits on the crystallographic orientation of the crystal plate in thin section. Birefringence can be used to estimate the composition of binary solid solutions displaying moderate to high interference colors if the optical orientation can be established. Computer color management techniques provide estimation of retardation values derived from interference colors to within a few nanometres in the range 250 to 1650 nanometres. These color management techniques can also be used to create charts and diagrams with retardation values as one variable and other mineral properties and compositions as the other variable. On such diagrams, interference colors can be painted, the color bands normal to the retardation axis like Michel-Levy charts.

  9. Correction of Birefringence and Thermal Lensing in Nonreciprocal Resonators by use of a Dynamic Imaging Mirror

    NASA Astrophysics Data System (ADS)

    Moshe, Inon; Jackel, Steven

    2000-08-01

    Enhanced correction of thermally induced birefringence in the presence of strong single-pass, azimuthally dependent bipolar focusing was achieved in single-rod laser oscillators by use of an adaptive optic rear mirror with image relay and aberration correction capabilities. Together with a Faraday rotator, the imaging variable radius mirror was successfully tested in stable and unstable Nd:Cr:GSGG power oscillators under variable pump power conditions from 0 to 800 W. Birefringence correction in the absence of ray retracing was achieved.

  10. Correction of birefringence and thermal lensing in nonreciprocal resonators by use of a dynamic imaging mirror.

    PubMed

    Moshe, I; Jackel, S

    2000-08-20

    Enhanced correction of thermally induced birefringence in the presence of strong single-pass, azimuthally dependent bipolar focusing was achieved in single-rod laser oscillators by use of an adaptive optic rear mirror with image relay and aberration correction capabilities. Together with a Faraday rotator, the imaging variable radius mirror was successfully tested in stable and unstable Nd:Cr:GSGG power oscillators under variable pump power conditions from 0 to 800 W. Birefringence correction in the absence of ray retracing was achieved. PMID:18350015

  11. PCTFE as a solution to birefringence in atom trap viewports

    SciTech Connect

    Warner, C. L.; Behr, J. A.; Gorelov, A.

    2014-11-15

    We have developed and characterized optical viewports with the glass-to-metal seal made by the plastic PCTFE (polychlorotrifluoroethylene). The goal is to reduce stress-induced birefringence while maintaining ultra-high vacuum compatibility. We have maintained a Stokes parameter S{sub 3} of 0.9986, and achieved <5 × 10{sup −11} Torr partial pressure of air. We have also measured the diffusion and permeation of helium through PCTFE and placed upper limits on nitrogen, oxygen, and argon permeation, as PCTFE has been suggested as an o-ring for transport of environmental noble gas samples, though we know of no other noble gas measurements.

  12. Polarized fiber optical parametric amplification in randomly birefringent fibers.

    PubMed

    Wang, S H; Xu, Xinchuan; Wai, P K A

    2015-12-14

    A comprehensive theoretical model to investigate phase matching in degenerate polarized fiber optical parametric amplifiers (FOPAs) in randomly birefringent fibers is developed. We show that in the small signal region, simulation results from the proposed model agree well with the experimental results. It was also shown that four waves mixing (FWM) effect could compensate polarization mode dispersion (PMD) induced phase mismatch. Similar to counter-propagating fiber Raman amplifiers (FRAs), the degree of polarization of FOPAs approaches unity exponentially with the gain but at a larger rate 1/Γ. Thus larger polarization-pulling can be achieved in FOPAs than the counter-propagating FRAs for the same gain. PMID:26699064

  13. Dichroic Bragg reflectors based on birefringent porous silicon

    SciTech Connect

    Diener, J.; Kunzner, N.; Kovalev, D.; Gross, E.; Timoshenko, V. Yu.; Polisski, G.; Koch, F.

    2001-06-11

    Multilayers of anisotropically nanostructured silicon (Si) have been fabricated and studied by polarization-resolved reflection measurements. Alternating layers having different refractive indices exhibit additionally a strong in-plane anisotropy of their refractive index (birefringence). Therefore, a stack of layers, acting as a distributed Bragg reflector, has two distinct reflection bands, depending on the polarization of the incident linearly polarized light. This effect is governed by a three-dimensional (in-plane and in-depth) variation of the refractive index. These structures can yield optical effects which are difficult to achieve with conventional Bragg reflectors. {copyright} 2001 American Institute of Physics.

  14. PCTFE as a solution to birefringence in atom trap viewports

    NASA Astrophysics Data System (ADS)

    Warner, C. L.; Behr, J. A.; Gorelov, A.

    2014-11-01

    We have developed and characterized optical viewports with the glass-to-metal seal made by the plastic PCTFE (polychlorotrifluoroethylene). The goal is to reduce stress-induced birefringence while maintaining ultra-high vacuum compatibility. We have maintained a Stokes parameter S3 of 0.9986, and achieved <5 × 10-11 Torr partial pressure of air. We have also measured the diffusion and permeation of helium through PCTFE and placed upper limits on nitrogen, oxygen, and argon permeation, as PCTFE has been suggested as an o-ring for transport of environmental noble gas samples, though we know of no other noble gas measurements.

  15. Crystal chemistry of birefringent hydrogrossular

    NASA Astrophysics Data System (ADS)

    Antao, Sytle M.

    2015-06-01

    Crystal structure refinements of two fine-grained, massive, birefringent hydrogarnet samples from South Africa [1. green "jade" and 2. pink "jade"] were carried out with the Rietveld method, cubic space group and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Electron-microprobe analysis (EMPA) gave bulk compositions as follows: (1) (Ca2.997Mg0.003)Σ3{Al1.794Fe{0.196/3+}Cr{0.004/3+}Mn{0.003/3+}Ti{0.002/4+}}Σ2[(SiO4)2.851(O4H4)0.151]Σ3 and (2) (Ca2.993Mg0.007)Σ3{Al1.977Fe{0.020/3+}Mn{0.003/3+}Cr{0.001/3+}}Σ2[(SiO4)2.272(O4H4)0.730]Σ3. Their crystal structure was modeled well as indicated by the Rietveld refinement statistical indicators where the reduced χ2 and overall R ( F 2) values are 1.133 and 0.0467, respectively, for sample 1 and 1.308 and 0.0342 for sample 2. Two cubic phases are contained in each sample. For phase 1a in sample 1, the weight fraction (%), unit-cell parameter (Å), and O-H bond distance (Å) are as follows: 74.4(1), a = 11.88874(4), and O-H = 0.98(9); the corresponding data for phase 1b are 25.6(1), a = 11.9280(5), and O-H = 0.91(9). For phase 2a in sample 2, the corresponding data are 52.0(1), a = 12.0591(1), and O-H = 0.90(6); the corresponding data for phase 2b are 48.0(1), a = 11.9340(2), and O-H = 0.90(7). The anisotropic displacement ellipsoids for the O atoms show no unusual features and are not elongated along the "Si-O" bond direction, which is written as Z-O, because of the general formula, X3Y2Z3O12, for garnet. Phase 1a is near end-member grossular, ideally Ca3Al2Si3O12. The deficiencies of the site occupancy factors ( sofs) for the Si (=Z) site indicate that there are significant [O4H4]4- replacing [SiO4]4-. The Z-O distance is large in phase 1b, phases 2a, and 2b compared to a typical Z-O distance in anhydrous grossular or phase 1a. The H atoms occur in different environments around the vacant Z site in the two samples, and they may also bond to the O atoms surrounding the X and Y sites

  16. Birefringent Polarization Ray Tracing: Theory and Applications

    NASA Astrophysics Data System (ADS)

    McClain, Stephen Charles

    Birefringent polarization ray tracing is an extension of geometric ray tracing. In addition to calculating ray paths and phases, it also analyzes the state of polarization through birefringent devices. Some systems containing birefringent elements include optical computers, radiometers, optical isolators, bar code scanners, and optical data storage systems. This dissertation derives explicit algorithms for polarization ray tracing through anisotropic media, optically active media, and anisotropic optically active media, such as quartz. The objective was to go beyond the electromagnetic relations to establish algorithms in standard ray tracing format, ready for direct inclusion into lens design software. The algorithms, derived from Maxwell's equations, constitutive relations, and boundary conditions, calculate the wavevector, ray vector, optical path length, refractive index, and polarization state of a ray. Generalized Fresnel relations govern the division of energy at each interface into two transmitted and two reflected modes. The algorithms are applied to calculate the polarization aberrations of a variety of birefringent devices. In particular, it is established that the polarization properties of quartz vary significantly (>20%) over angles of only 5 degrees. This limits the useful field of view of quartz devices. Field of view aberrations of birefringent elements can critically affect the performance of optical systems. Also, design guidelines are presented for pseudodepolarizers. These devices spatially scramble the polarization. Inserted into an instrument, a depolarizer negates the polarization sensitivity of the elements which follow it. Presented in detail is the design and analysis of a depolarizer for use in a spectrometer on NASA's Earth Observing System (EOS).

  17. Birefringent polarization ray tracing: Theory and applications

    NASA Astrophysics Data System (ADS)

    McClain, Stephen Charles

    1992-06-01

    Birefringent polarization ray tracing is an extension of geometric ray tracing. In addition to calculating ray paths and phases, it also analyzes the state of polarization through birefringent devices. Some systems containing birefringent elements include optical computers, radiometers, optical isolators, bar code scanners, and optical data storage systems. This dissertation derives explicit algorithms for polarization ray tracing through anisotropic media, optically active media, and anisotropic optically active media, such as quartz. The objective was to go beyond the electromagnetic relations to establish algorithms in standard ray tracing format, ready for direct inclusion into lens design software. The algorithms, derived from Maxwell's equations, constitutive relations, and boundary conditions, calculate the wavevector, ray vector, optical path length, refractive index, and polarization state of a ray. Generalized Fresnel relations govern the division of energy at each interface into two transmitted and two reflected modes. The algorithms are applied to calculate the polarization aberrations of a variety of birefringent devices. In particular, it is established that the polarization properties of quartz vary significantly (greater than 20 percent) over angles of only 5 degrees. This limits the useful field of view of quartz devices. Field of view aberrations of birefringent elements can critically affect the performance of optical systems. Also, design guidelines are presented for pseudodepolarizers. These devices spatially scramble the polarization. Inserted into an instrument, a depolarizer negates the polarization sensitivity of the elements which follow it. Presented in detail is the design and analysis of a depolarizer for use in a spectrometer on NASA's Earth Observing System (EOS).

  18. Highly birefringent suspended-core photonic microcells for refractive-index sensing

    SciTech Connect

    Wang, Chao; Jin, Wa; Ma, Jun; Jin, Wei Yang, Fan; Ho, Hoi Lut; Liao, Changrui; Wang, Yiping

    2014-08-11

    An in-line photonic microcell with a highly birefringent suspended microfiber core is fabricated by locally heating and pressurizing selected air-holes of an endless single mode photonic crystal fiber. The microfiber core has rhombus-like cross-sectional geometry and could achieve a high birefringence of up to 10{sup −2}. The microfiber core is fixed at the center of the microcell by thin struts attached to an outer jacket tube, which protects and isolates the microfiber from environmental contaminations. Highly sensitive and robust refractive index sensors based on such microcells are experimentally demonstrated.

  19. Structural design for birefringent holey fiber with a beat length insensitive to wavelength.

    PubMed

    Lin, Jian-Qiang; Shi, Zhi-Dong; Li, Ming-Jia; Chen, Hua

    2009-09-01

    By combination of two defect structures with positive and negative birefringence, we design a holey fiber with a beat length that is less sensitive to wavelength. The influence of different structural parameters on birefringence of holey fiber is calculated by the finite-difference beam propagation method. A stable beat length can be achieved at some given wavelength window by adjusting the parameters. An almost uniform beat length with a greater than 180 nm bandwidth at 1310 and 1550 nm wavelength windows is obtained, which is useful for the design and fabrication of fiber-optic wave plates with a wide band. PMID:19724314

  20. Electro-optical tunable birefringent filter

    SciTech Connect

    Levinton, Fred M.

    2012-01-31

    An electrically tunable Lyot type filter is a Lyot that include one or more filter elements. Each filter element may have a planar, solid crystal comprised of a material that exhibits birefringence and is electro-optically active. Transparent electrodes may be coated on each face of the crystal. An input linear light polarizer may be located on one side of the crystal and oriented at 45 degrees to the optical axis of the birefringent crystal. An output linear light polarizer may be located on the other side of the crystal and oriented at -45 degrees with respect to the optical axis of the birefringent crystal. When an electric voltage is applied between the electrodes, the retardation of the crystal changes and so does the spectral transmission of the optical filter.

  1. Highly birefringent polymer side-hole fiber for hydrostatic pressure sensing.

    PubMed

    Martynkien, Tadeusz; Wojcik, Grzegorz; Mergo, Pawel; Urbanczyk, Waclaw

    2015-07-01

    We report on the fabrication of a birefringent side-hole polymer optical fiber with an elliptical core made of polymethyl metacrylate-polystyrene (PMMA/PS) copolymer and pure PMMA cladding. The fiber core is located in a narrow PMMA bridge separating the holes. Two fibers with different bridge thickness were fabricated and characterized. We demonstrate, experimentally and numerically, that, by narrowing the bridge between the holes, one can increase simultaneously the fiber birefringence and the polarimetric sensitivity to hydrostatic pressure. In the fiber with the bridge as narrow as 5 μm, we achieved a record-high polarimetric sensitivity to hydrostatic pressure ranging between 175 and 140 rad/MPa/m in the spectral range of 600-830 nm. The phase modal birefringence in this fiber is also high and exceeds 3×10(-5) at 600 nm, which results in small polarization cross talk. PMID:26125360

  2. Electrically tunable birefringence of a polymer composite with long-range orientational ordering of liquid crystals.

    PubMed

    Choi, Byeongdae; Song, Seongkyu; Jeong, Soon Moon; Chung, Seok-Hwan; Glushchenko, Anatoliy

    2014-07-28

    We report an optical film with electrically tunable birefringence in which the liquid crystals (LCs), mixed with the host polymer, form long-range ordering. The film was prepared through polymerization without phase separation between the LCs and polymers. Driving voltage below 30 V for full switching of birefringence is achieved in a 6 μm-thick film. Electro-optical investigations for the film suggest that the long-range ordering of the LCs mixed in the film caused by polymerization lead to rotations of the LCs as well as optical anisotropy in the film. These films with electrically tunable birefringence could have applications as flexible light modulators and phase retardation films for 2D-3D image switching. PMID:25089422

  3. Optical stress sensor based on electro-optic compensation for photoelastic birefringence in a single crystal

    SciTech Connect

    Li Changsheng

    2011-09-20

    An optical stress sensor is proposed by using a single crystal with both electro-optic and photoelastic effects. Different from previous crystal-based stress sensors, the proposed sensor is based on electro-optic compensation for stress-induced birefringence and does not need an additional quarter-wave plate or modulator, because the stress-sensing element is simultaneously used as an electro-optic compensator. Candidate sensing materials include electro-optic crystals of the 3 m symmetry group and all glass with large Kerr coefficients. A primary experiment has demonstrated that the stress-induced birefringence in lithium niobate crystal can be compensated by its electro-optic birefringence. The proposed stress sensor is compact and low cost, and it is possible to achieve closed-loop stress measurement.

  4. Research on spectroscopic imaging. Volume 1: Technical discussion. [birefringent filters

    NASA Technical Reports Server (NTRS)

    Title, A.; Rosenberg, W.

    1979-01-01

    The principals of operation and the capabilities of birefringent filters systems are examined. Topics covered include: Lyot, Solc, and partial polarizer filters; transmission profile management; tuning birefringent filters; field of view; bandpass control; engineering considerations; and recommendations. Improvements for field of view effects, and the development of birefringent filters for spaceflight are discussed in appendices.

  5. Vacuum birefringence by Compton backscattering through a strong field

    NASA Astrophysics Data System (ADS)

    Wistisen, Tobias N.; Uggerhøj, Ulrik I.

    2013-09-01

    We propose a novel scheme to measure nonlinear effects in electrodynamics arising from QED corrections. Our theoretical starting point is the Heisenberg-Euler-Schwinger effective Lagrangian which predicts that a vacuum with a strong static electromagnetic field turns birefringent. We propose to employ a pulsed laser to create Compton backscattered photons off a high energy electron beam. These photons will pass through a strong static magnetic field, which according to the QED prediction changes the state of polarization of the radiation—an effect proportional to the photon energy. This change will be measured by using an aligned single crystal, since a large difference in the pair production cross sections at high energies can be achieved with proper orientation of the crystal. As an example we will consider the machine, LHeC, under consideration at CERN as the source of these electrons, and an LHC dipole magnet as the source of the strong static magnetic field. In the proposed experimental setup the birefringence effect will be manifested in a difference in the number of pairs created in the polarizer crystal as the initial laser light has a varying state of polarization, achieved with a rotating quarter wave plate. This will be seen as a clear peak in the Fourier transform spectrum of the pair-production rate signal, which can be obtained with 3 hours of measurement. We also comment on the sensitivity of the experiment, to the existence of an axion, a hypothetical spin-0 particle that couples to two photons.

  6. Modeling and minimizing interference from corneal birefringence in retinal birefringence scanning for foveal fixation detection

    PubMed Central

    Irsch, Kristina; Gramatikov, Boris; Wu, Yi-Kai; Guyton, David

    2011-01-01

    Utilizing the measured corneal birefringence from a data set of 150 eyes of 75 human subjects, an algorithm and related computer program, based on Müller-Stokes matrix calculus, were developed in MATLAB for assessing the influence of corneal birefringence on retinal birefringence scanning (RBS) and for converging upon an optical/mechanical design using wave plates (“wave-plate-enhanced RBS”) that allows foveal fixation detection essentially independently of corneal birefringence. The RBS computer model, and in particular the optimization algorithm, were verified with experimental human data using an available monocular RBS-based eye fixation monitor. Fixation detection using wave-plate-enhanced RBS is adaptable to less cooperative subjects, including young children at risk for developing amblyopia. PMID:21750772

  7. Polarized light in birefringent samples (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Chue-Sang, Joseph; Bai, Yuqiang; Ramella-Roman, Jessica

    2016-02-01

    Full-field polarized light imaging provides the capability of investigating the alignment and density of birefringent tissue such as collagen abundantly found in scars, the cervix, and other sites of connective tissue. These can be indicators of disease and conditions affecting a patient. Two-dimensional polarized light Monte Carlo simulations which allow the input of an optical axis of a birefringent sample relative to a detector have been created and validated using optically anisotropic samples such as tendon yet, unlike tendon, most collagen-based tissues is significantly less directional and anisotropic. Most important is the incorporation of three-dimensional structures for polarized light to interact with in order to simulate more realistic biological environments. Here we describe the development of a new polarization sensitive Monte Carlo capable to handle birefringent materials with any spatial distribution. The new computational platform is based on tissue digitization and classification including tissue birefringence and principle axis of polarization. Validation of the system was conducted both numerically and experimentally.

  8. Modeling, simulation, and analysis of birefringent effects in plastic optics

    NASA Astrophysics Data System (ADS)

    Adhikari, Achyut; Asundi, Anand

    2015-09-01

    Plastic optics has been widely used in different application. They have been facing birefringent effects during manufacturing or during certain application. Finite element modeling of plastic optics in CAD interface is done along with experimental and theoretical comparison of the specimen with the help of solid mechanics and image processing. Low birefringence plastic optics is chosen for the experiment and varying load is applied to observe the characteristics both in experiment and simulation. Low birefringence polariscope was used to measure the birefringence in the plastic specimen. Birefringence is caused due to many effects like stress induced birefringence temperature induced due to thermal gradient and pressure during manufacturing. Here stress is induced on low birefringence specimen by two point compression loading and is compared on the base of solid mechanics, finite element modeling and image processing. The results were found to be similar and convincing.

  9. CMB polarization systematics, cosmological birefringence, and the gravitational waves background

    SciTech Connect

    Pagano, Luca; Bernardis, Paolo de; Gubitosi, Giulia; Masi, Silvia; Melchiorri, Alessandro; Piacentini, Francesco; De Troia, Grazia; Natoli, Paolo; Polenta, Gianluca

    2009-08-15

    Cosmic microwave background experiments must achieve very accurate calibration of their polarization reference frame to avoid biasing the cosmological parameters. In particular, a wrong or inaccurate calibration might mimic the presence of a gravitational wave background, or a signal from cosmological birefringence, a phenomenon characteristic of several nonstandard, symmetry breaking theories of electrodynamics that allow for in vacuo rotation of the polarization direction of the photon. Noteworthly, several authors have claimed that the BOOMERanG 2003 (B2K) published polarized power spectra of the cosmic microwave background may hint at cosmological birefringence. Such analyses, however, do not take into account the reported calibration uncertainties of the BOOMERanG focal plane. We develop a formalism to include this effect and apply it to the BOOMERanG dataset, finding a cosmological rotation angle {alpha}=-4.3 deg. {+-}4.1 deg. We also investigate the expected performances of future space borne experiment, finding that an overall miscalibration larger then 1 deg. for Planck and 0.2 deg. for the Experimental Probe of Inflationary Cosmology, if not properly taken into account, will produce a bias on the constraints on the cosmological parameters and could misleadingly suggest the presence of a gravitational waves background.

  10. Investigations on birefringence effects in polymer optical fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Hu, X.; Sáez-Rodríguez, D.; Bang, O.; Webb, D. J.; Caucheteur, C.

    2014-05-01

    Step-index polymer optical fiber Bragg gratings (POFBGs) and microstructured polymer optical fiber Bragg gratings (mPOFBGs) present several attractive features, especially for sensing purposes. In comparison to FBGs written in silica fibers, they are more sensitive to temperature and pressure because of the larger thermo-optic coefficient and smaller Young's modulus of polymer materials. (M)POFBGs are most often photowritten in poly(methylmethacrylate) (PMMA) materials using a continuous-wave 325 nm HeCd laser. For the first time to the best of our knowledge, we study photoinduced birefringence effects in (m)POFBGs. To achieve this, highly reflective gratings were inscribed with the phase mask technique. They were then monitored in transmission with polarized light. For this, (m)POF sections a few cm in length containing the gratings were glued to angled silica fibers. Polarization dependent loss (PDL) and differential group delay (DGD) were computed from the Jones matrix eigenanalysis using an optical vector analyser. Maximum values exceeding several dB and a few picoseconds were obtained for the PDL and DGD, respectively. The response to lateral force was finally investigated. As it induces birefringence in addition to the photo-induced one, an increase of the PDL and DGD values were noticed.

  11. Vacuum birefringence in strong inhomogeneous electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Karbstein, Felix; Gies, Holger; Reuter, Maria; Zepf, Matt

    2015-10-01

    Birefringence is one of the fascinating properties of the vacuum of quantum electrodynamics (QED) in strong electromagnetic fields. The scattering of linearly polarized incident probe photons into a perpendicularly polarized mode provides a distinct signature of the optical activity of the quantum vacuum and thus offers an excellent opportunity for a precision test of nonlinear QED. Precision tests require accurate predictions and thus a theoretical framework that is capable of taking the detailed experimental geometry into account. We derive analytical solutions for vacuum birefringence which include the spatio-temporal field structure of a strong optical pump laser field and an x-ray probe. We show that the angular distribution of the scattered photons depends strongly on the interaction geometry and find that scattering of the perpendicularly polarized scattered photons out of the cone of the incident probe x-ray beam is the key to making the phenomenon experimentally accessible with the current generation of FEL/high-field laser facilities.

  12. Spectral characterization of nanostructured birefringent porous silicon.

    PubMed

    Hakshur, Keren; Yifat, Yuval; Levin, Amit; Ruschin, Shlomo

    2015-12-20

    We present measurements and analysis of the reflection spectrum of white light from a highly birefringent porous silicon layer at different polarization states. We report an anomalous pattern in the spectrum of linearly polarized light at 45° with respect to the principal axes of the layer. This spectrum comprises a combination of two interference effects, namely the Fabry-Perot-type multiple-beam interference present in a simple thin film, and a two-wave interference caused by the beat of two combined orthogonally polarized waves propagating in the birefringent medium. We perform a Fourier analysis of the measured reflected spectra. This analysis furnishes a powerful tool in order to separate the two interference mechanisms and determine the degree of coherence of their superposition. PMID:26837030

  13. Compact snapshot birefringent imaging Fourier transform spectrometer

    NASA Astrophysics Data System (ADS)

    Kudenov, Michael W.; Dereniak, Eustace L.

    2010-08-01

    The design and implementation of a compact multiple-image Fourier transform spectrometer (FTS) is presented. Based on the multiple-image FTS originally developed by A. Hirai, the presented device offers significant advantages over his original implementation. Namely, its birefringent nature results in a common-path interferometer which makes the spectrometer insensitive to vibration. Furthermore, it enables the potential of making the instrument ultra-compact, thereby improving the portability of the sensor. The theory of the birefringent FTS is provided, followed by details of its specific embodiment. A laboratory proof of concept of the sensor, designed and developed at the Optical Detection Lab, is also presented. Spectral measurements of laboratory sources are provided, including measurements of light-emitting diodes and gas-discharge lamps. These spectra are verified against a calibrated Ocean Optics USB2000 spectrometer. Other data were collected outdoors, demonstrating the sensor's ability to resolve spectral signatures in standard outdoor lighting and environmental conditions.

  14. Polarimetric characterization of birefringent filter components.

    PubMed

    Mudge, Jason; Mitchell, Keith; Tarbell, Theodore

    2015-01-10

    Over the past 75 years, birefringent filter technology has evolved significantly. For nearly that same period of time, these filters have been designed and used by solar scientists to study the Sun. Prior to assembling these types of filters, each component, e.g., polarizers and wave plates, is characterized to determine its polarimetric parameters to ensure the desired filter design performance. With time and cost becoming an ever increasing issue, it is imperative to test components designated for a birefringent filter efficiently. This article addresses a shift to increased efficiency when testing components of very low volume (<5 units) solar research filters that minimizes high-priced hardware expenditures, i.e., Mueller matrix spectropolarimeter. PMID:25967624

  15. Performance analysis of intracavity birefringence sensing

    SciTech Connect

    Yoshino, Toshihiko

    2008-05-10

    The performance of intracavity birefringence sensing by use of a standing-wave laser is theoretically analyzed when the cavity involves internal reflection. On the three-mirror compound cavity model, the condition for converting an optical path length into a laser frequency or a retardation into an optical beat frequency with good linearity and little uncertainty is derived as a function of the cavity parameters and is numerically analyzed.

  16. Coherent control of birefringence and optical activity

    NASA Astrophysics Data System (ADS)

    Mousavi, Seyedmohammad A.; Plum, Eric; Shi, Jinhui; Zheludev, Nikolay I.

    2014-07-01

    We show that polarization effects due to anisotropy and chirality affecting a wave propagating through a thin slab of material can be controlled by another electromagnetic wave. No nonlinearity of the metamaterial slab is required and the control can be exercised at arbitrarily low intensities. In proof-of-principle experiments with anisotropic and chiral microwave metamaterials, we show that manifestations of linear and circular birefringence and dichroism can be modulated by the control wave from their maximum value to zero.

  17. Reconsidering the origins of Forsbergh birefringence patterns

    NASA Astrophysics Data System (ADS)

    Schilling, A.; Kumar, A.; McQuaid, R. G. P.; Glazer, A. M.; Thomas, P. A.; Gregg, J. M.

    2016-07-01

    In 1949, Forsbergh, Jr. reported spontaneous spatial ordering in the birefringence patterns seen in flux-grown BaTi O3 crystals under the transmission polarized light microscope [Phys. Rev. 76, 1187 (1949), 10.1103/PhysRev.76.1187]. Stunningly regular square-net arrays were often only found within a finite temperature window and could be induced on both heating and cooling, suggesting genuine thermodynamic stability. At the time, Forsbergh rationalized the patterns to have resulted from the impingement of ferroelastic domains, creating a complex tessellation of variously shaped domain packets. However, no direct evidence for the intricate microstructural arrangement proposed by Forsbergh has subsequently been found. Moreover, there are no robust thermodynamic arguments to explain the finite region of thermal stability, its occurrence just below the Curie temperature, and the apparent increase in entropy associated with the loss of the Forsbergh pattern on cooling. Despite decades of research on ferroelectrics, this ordering phenomenon and its thermodynamic origin have hence remained a mystery. In this paper, we reexamine the microstructure of flux-grown BaTi O3 crystals, which show Forsbergh birefringence patterns. Given an absence of any obvious arrays of domain polyhedra or even regular shapes of domain packets, we suggest an alternative origin for the Forsbergh pattern in which sheets of orthogonally oriented ferroelastic stripe domains simply overlay one another. We show explicitly that the Forsbergh birefringence pattern occurs if the periodicity of the stripe domains is above a critical value. Moreover, by considering well-established semiempirical models, we show that the significant domain coarsening needed to generate the Forsbergh birefringence is fully expected in a finite window below the Curie temperature. We hence present a much more straightforward rationalization of the Forsbergh pattern than that originally proposed in which exotic thermodynamic

  18. Spectral-Content Readout Of Birefringent Sensor

    NASA Technical Reports Server (NTRS)

    Redner, Alex S.

    1993-01-01

    Stresses and strains measured optically at temperatures up to 2,000 degrees F. Spectrum of light processed through polarizer, sensor, analyzer, and associated optical components measured and processed to extract amount of retardation and, equivalently, stress-induced birefringence in sensor. Method offers same advantages as electrical strain sensors, including acquisition of data from multiple locations and under dynamic conditions. Additional advantage: immunity of fiber-optic transmission to interference by electromagnetic interference at radio and lower frequencies.

  19. Periodic femtosecond filamentation in birefringent media

    NASA Astrophysics Data System (ADS)

    Blonskyi, I.; Kadan, V.; Shynkarenko, Y.; Yarusevych, O.; Korenyuk, P.; Puzikov, V.; Grin', L.

    2015-09-01

    We report on the experimental observation of periodic modulation of the axial luminescence intensity along the femtosecond filament track in sapphire and crystal quartz. The physical reason for the modulation is a cyclic transformation of the polarization state of the light pulse traveling in birefringent medium, caused by the phase raid between the ordinary and extraordinary rays, and different cross sections of multiphoton absorption for linear and circular polarizations.

  20. High-birefringence, low-loss porous fiber for single-mode terahertz-wave guidance.

    PubMed

    Chen, Na-na; Liang, Jian; Ren, Li-yong

    2013-07-20

    A new kind of polymer porous fiber with elliptical air-holes is designed for obtaining high birefringence in the terahertz (THz) frequency range in this paper. Using the finite element method, the properties of this kind of fiber are simulated in detail including the single-mode propagation condition, the birefringence, and the loss. Theoretical results indicate that the single-mode THz wave in the frequency range from 0.73 to 1.22 THz can be guided in the fiber; the birefringence can be enhanced by rotating the major axis of the elliptical air-hole and there exists an optimal rotating angle at 30°. At this optimal angle a birefringence as high as 0.0445 can be obtained in a wide frequency range. Low-loss THz guidance can be achieved owing to the effective reduction of the material absorption in such a porous fiber. This research is useful for polarization-maintaining THz-wave guidance. PMID:23872779

  1. Femtosecond laser pulse induced birefringence in optically isotropic glass.

    SciTech Connect

    Vawter, Gregory Allen; Luk, Ting Shan; Guo, Junpeng; Yang, Pin; Burns, George Robert

    2003-07-01

    We used a regeneratively amplified Ti:sapphire femtosecond laser to create optical birefringence in an isotropic glass medium. Between two crossed polarizers, regions modified by the femtosecond laser show bright transmission with respect to the dark background of the isotropic glass. This observation immediately suggests that these regions possess optical birefringence. The angular dependence of transmission through the laser-modified region is consistent with that of an optically birefringent material. Laser-induced birefringence is demonstrated in different glasses, including fused silica and borosilicate glass. Experimental results indicate that the optical axes of laser-induced birefringence can be controlled by the polarization direction of the femtosecond laser. The amount of laser-induced birefringence depends on the pulse energy level and number of accumulated pulses.

  2. Highly birefringent low-mode-asymmetry microstructured optical fibres

    SciTech Connect

    Denisov, A N; Levchenko, A E; Semenov, S L; Dianov, Evgenii M

    2011-03-31

    A novel birefringent microstructured fibre (BMF) design is proposed, and its birefringence and dispersion characteristics are analysed using the finite element method. The results indicate that the proposed BMF design ensures high birefringence ({approx}5x10{sup -3}) at a low mode asymmetry. At a certain core ellipticity, the BMF configurations considered may have equal mode field sizes along two orthogonal axes. (fibre optics)

  3. Using cellophane tape to experience interference birefringent filters

    NASA Astrophysics Data System (ADS)

    Puerto, D.; Velásquez, P.; Sánchez-López, M. M.; Moreno, I.; Mateos, F.

    2005-10-01

    In this work we propose and demonstrate a very simple method to fabricate interference multilayer birefringent filters. We employ the birefringence properties of common cellophane. Cellophane tape layers can be very easily superimposed with different orientations in order to generate different spectral responses. We experimentally demonstrate this behaviour with the aid of a portable spectrophotometer. This technique represents a simple and inexpensive way of experimentally investigating the optical properties of birefringent filters.

  4. Detecting strain in birefringent materials using spectral polarimetry

    NASA Technical Reports Server (NTRS)

    Ragucci, Anthony J. (Inventor); Cisar, Alan J. (Inventor); Huebschman, Michael L. (Inventor); Garner, Harold R. (Inventor)

    2010-01-01

    A method, computer program product and system for analyzing multispectral images from a plurality of regions of birefringent material, such as a polymer film, using polarized light and a corresponding polar analyzer to identify differential strain in the birefringent material. For example, the birefringement material may be low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinylidene chloride, polyester, nylon, or cellophane film. Optionally, the method includes generating a real-time quantitative strain map.

  5. Transfer matrix for treating stratified media including birefringent crystals.

    PubMed

    Essinger-Hileman, Thomas

    2013-01-10

    Birefringent crystals are extensively used to manipulate polarized light. The generalized transfer matrix developed allows efficient calculation of the full polarization state of light transmitted through and reflected by a stack of arbitrarily many discrete layers of isotropic and birefringent materials at any frequency and angle of incidence. The matrix of a uniaxial birefringent crystal with arbitrary rotation is calculated, along with its reduction to the matrix of an isotropic medium. This method is of great practical importance where tight control of systematic effects is needed in optical systems employing birefringent crystals, one example being wave plates used by cosmic microwave background polarimetry with wide field-of-view telescopes. PMID:23314637

  6. Electric birefringence spectroscopy of montmorillonite particles.

    PubMed

    Arenas-Guerrero, Paloma; Iglesias, Guillermo R; Delgado, Ángel V; Jiménez, María L

    2016-06-14

    Electric birefringence (EB) of suspensions of anisotropic particles can be considered an electrokinetic phenomenon in a wide sense, as both liquid motions and polarization of the electrical double layer (EDL) of the particles participate in the process of particle orientation under the applied field. The EB spectrum can be exploited for obtaining information on the dimensions, average value and anisotropy of the surface conductivity of the particles, and the concentration and Maxwell-Wagner polarization of the EDLs. It is thus a highly informative technique, applicable to non-spherical particles. In this paper, we investigate the birefringent response of plate-like montmorillonite particles as a function of the frequency and amplitude of the applied AC electric field, for different compositions (pH, ionic strength, particle concentration) of the suspensions. The transient electric birefringence (i.e., the decay of the refractive index anisotropy with time when the field is switched off) is used for estimating the average dimensions of the particle axes, by modeling it as an oblate spheroid. The obtained values are very similar to those deduced from electron microscopy determinations. The frequency spectra show a very distinct behaviour at low (on the order of a few Hz) and high (up to several MHz) frequencies: the α and Maxwell-Wagner-O'Konski relaxations, characteristic of EDLs, are detected at frequencies above 10 kHz, and they can be well explained using electrokinetic models for the polarization of EDLs. At low frequencies, in contrast, the birefringence changes to negative, an anomalous response meaning that the particles tend to orient with their symmetry axis parallel to the field. This anomaly is weaker at basic pH values, high ionic strengths and low concentrations. The results can be explained by considering the polydispersity of real samples: the fastest particles redistribute around the slowest ones, inducing a hydrodynamic torque opposite to that of

  7. Linear birefringence in split-ring resonators.

    PubMed

    Iyer, Srinivasan; Popov, Sergei; Friberg, Ari T

    2012-06-01

    We study polarization-dependent transmission of light through arrays of single-slit split-ring resonator (SSRR) based systems at normal incidence using finite integration time domain (FITD) and finite element methods (FEM). It is found that a conventional planar array of SSRRs acts as an effective optical wave plate at certain polarizations of incident light. The effect is attributed to the intrinsic linear birefringence of individual SSRRs. A comparison is made with other split-ring resonator-based systems exhibiting wave-plate-like properties due to inter-SSRR coupling. PMID:22660115

  8. Experiment to measure vacuum birefringence: Conceptual design

    NASA Astrophysics Data System (ADS)

    Mueller, Guido; Tanner, David; Doebrich, Babette; Poeld, Jan; Lindner, Axel; Willke, Benno

    2016-03-01

    Vacuum birefringence is another lingering challenge which will soon become accessible to experimental verification. The effect was first calculated by Euler and Heisenberg in 1936 and is these days described as a one-loop correction to the differential index of refraction between light which is polarized parallel and perpendicular to an external magnetic field. Our plan is to realize (and slightly modify) an idea which was originally published by Hall, Ye, and Ma using advanced LIGO and LISA technology and the infrastructure of the ALPS light-shining-through-walls experiment following the ALPS IIc science run. This work is supported by the Deutsche Forschungsgemeinschaft and the Heising-Simons Foundation.

  9. Superluminal group velocity in a birefringent crystal

    SciTech Connect

    Halvorsen, Tore Gunnar; Leinaas, Jon Magne

    2008-02-15

    We examine the effect of superluminal signal propagation through a birefringent crystal, where the effect is not due to absorption or reflection, but to the filtration of a special polarization component. We first examine the effect by a stationary phase analysis, with results consistent with those of an earlier analysis of the system. We supplement this analysis by considering the transit of a Gaussian wave and find bounds for the validity of the stationary phase result. The propagation of the Gaussian wave is illustrated by figures.

  10. Method and apparatus for measuring birefringent particles

    DOEpatents

    Bishop, James K.; Guay, Christopher K.

    2006-04-18

    A method and apparatus for measuring birefringent particles is provided comprising a source lamp, a grating, a first polarizer having a first transmission axis, a sample cell and a second polarizer having a second polarization axis. The second polarizer has a second polarization axis that is set to be perpendicular to the first polarization axis, and thereby blocks linearly polarized light with the orientation of the beam of light passing through the first polarizer. The beam of light passing through the second polarizer is measured using a detector.

  11. Measurement of birefringence inside a filament

    SciTech Connect

    Yuan Shuai; Wang, Tie-Jun; Chin, See Leang; Kosareva, Olga; Panov, Nikolay; Makarov, Vladimir; Zeng Heping

    2011-07-15

    We quantified the ultrafast birefringence induced in the filament in an atomic gas by measuring the filament-induced polarization rotation of a probe pulse. Based on the dephasing of the probe's orthogonal polarization components in argon, the experiment was done at 1 atm by copropagating a linearly polarized 400-nm probe pulse with an 800-nm pump pulse which generated the filament. The probe's elliptical polarization states were shown under various initial pump-probe polarization schemes. These states were verified by comparing the filament-induced probe polarization rotation angle and the ellipticity of the probe polarization.

  12. Smectic A Filled Birefringent Elements and Fast Switching Twisted Dual Frequency Nematic Cells Used for Digital Light Deflection

    NASA Technical Reports Server (NTRS)

    Pishnyak, Oleg; Golovin, Andrii; Kreminskia, Liubov; Pouch, John J.; Miranda, Felix A.; Winker, Bruce K.; Lavrentovich, Oleg D.

    2006-01-01

    We describe the application of smectic A (SmA) liquid crystals for beam deflection. SmA materials can be used in digital beam deflectors (DBDs) as fillers for passive birefringent prisms. 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. Fast rotation of the incident light polarization in DBDs is achieved by an electrically switched 90 twisted nematic (TN) cell.

  13. Direct measurement of birefringence in ion-exchanged planar waveguides

    NASA Astrophysics Data System (ADS)

    Fazio, E.; Ramadan, W. A.; Bertolotti, M.; Righini, G. C.

    1996-08-01

    A direct measurement of the birefringence of a planar waveguide obtained by Na+ - K + ion exchange was performed with a double Lloyd interferometer. The results are compared with those obtained by a round-robin test involving the same sample. Birefringence of as much as Delta n=(2.0+/-0.2) \\times 10-3 was measured.

  14. Special Temperature Features of the Birefringence of Lithium Tetraborate Crystals

    NASA Astrophysics Data System (ADS)

    Kushnir, O. S.; Burak, Ya. V.; Bevz, A. A.; Shopa, Ya. I.

    2000-05-01

    Using the Senarmont polarimetric method, the optical birefringence of lithium tetraborate crystals Li2B4O7 in the 290 480 K range was measured. The steplike temperature dependence of birefringence, the thermal hysteresis, and the thermooptic memory effect were observed, which are most likely associated with the presence of incommensurate phase modulation in lithium tetraborate.

  15. Form birefringence in porous semiconductors and dielectrics: A review

    SciTech Connect

    Golovan', L. A. Kashkarov, P. K.; Timoshenko, V. Yu.

    2007-07-15

    The phenomenon of optical anisotropy in porous semiconductors and dielectrics (porous silicon, gallium phosphide, and alumina) and photonic crystal structures formed on their basis is reviewed. It is shown that anisotropic nanostructuring of initially isotropic media leads to the occurrence of strong birefringence. Applicability of the effective-medium model to description of the form birefringence in porous semiconductors and dielectrics is discussed.

  16. Correction for losses in optical birefringent networks, a concept

    NASA Technical Reports Server (NTRS)

    Amman, E. O.

    1968-01-01

    Technique determines the effects of losses upon the performance of a birefringent network and shows how the desired amplitude transmittance of the network may be corrected /or predistorted/, prior to synthesizing the birefringent network, to prevent the effects of crystal losses.

  17. Interference birefringent filters fabricated with low cost commercial polymers

    NASA Astrophysics Data System (ADS)

    Velasquez, Pablo; del Mar Sánchez-López, María; Moreno, Ignacio; Puerto, Daniel; Mateos, Felipe

    2005-04-01

    We discuss a simple method for fabricating interference birefringent filters using common cellophane tape layers. Cellophane tape layers can be superimposed with different orientations to generate different spectral responses. We demonstrate this behavior with a portable spectrophotometer. This technique is a simple and inexpensive way of investigating the optical properties of birefringent filters.

  18. Study of stress birefringence for 193-nm immersion photomasks

    NASA Astrophysics Data System (ADS)

    Cotte, Eric; Selle, Michael; Bubke, Karsten; Teuber, Silvio

    2005-06-01

    The goal of the present study was to investigate and quantify reticle stress birefringence in exposure conditions. Birefringence can arise in fused silica photomask substrates due to their state of stress, and cause optical effects such as phase front distortion, ray bifurcation, and polarization changes. These effects potentially produce image blurring and illumination non-uniformity, leading to lower resolution and CD variations, respectively. The main sources of substrate stress studied were the absorber stack, the mounting of a pellicle, and the impact of initial reticle bow when chucking in an exposure tool. Jones calculus was used to relate birefringence at discrete locations in the reticle, derived from the state of stress, to the net birefringence experienced by light passing through the mask. Experimentally-obtained birefringence data as well as analytical calculations of stress birefringence caused by known states of stress were used to validate the models. These results can then be compared to photomask birefringence specifications or employed in optical simulations to determine the precise impact of this substrate stress birefringence.

  19. Carrier and chain formation dependence of birefringence in magnetic fluids

    NASA Astrophysics Data System (ADS)

    Abu-Safia, H.; Abu-Aljarayesh, I.; El-Ghanem, H. M.; Yusuf, N. A.

    1992-01-01

    Measurements of the birefringence in Fe 3O 4 magnetic fluids were undertaken in the temperature range 190-313 K in magnetic fields up to 0.7 kOe. Our results show that the birefringence increases with temperature exhibiting a maximum near the melting point, Tm, of the liquid carrier (kerosene, decalin and Isopar M). For T > Tm the birefringence follows a generalized Curie-Weiss law yielding positive ordering temperatures for the three samples. Moreover, our results show that the birefringence behaves irreversibly with temperature, in the decalin based sample. The results also show that the magnitude of the birefringence and the shape of the maximum change with the applied magnetic fields.

  20. Nematic liquid crystals exhibiting high birefringence

    NASA Astrophysics Data System (ADS)

    Thingujam, Kiranmala; Bhattacharjee, Ayon; Choudhury, Basana; Dabrowski, Roman

    2016-06-01

    Two fluorinated isothiocyanato nematic liquid crystalline compounds, 4'-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4'-pentylcyclohexyl-3, 5-difluoro-4-isothiocynatobiphenyl are studied in detail to obtain their different physical parameters. Optical polarizing microscopy, differential scanning calorimetry, density and dielectric studies have been carried out for the two samples. Both the samples were found to have high clearing temperature (>100 °C) and exhibit small enthalpy of transition. The two samples exhibit high optical birefringence (Δ n > 0.2). The values of order parameters for the two samples were obtained using different approaches, namely, Vuks', Neugebauer's, modified Vuks' and direct extrapolation method from birefringence data. Experimentally obtained values of order parameters have also been compared with theoretical Maier-Saupe values. The parallel and perpendicular components of dielectric permittivity values of the two compounds were also calculated and their anisotropy values were found to be small. The effect of temperature on the molecular dipole moment μ and the angle of inclination β of the dipole axis with the director have also been investigated in this work.

  1. Stokes parameters modulator for birefringent filters

    NASA Technical Reports Server (NTRS)

    Dollfus, A.

    1985-01-01

    The Solar Birefringent Filter (Filter Polarisiant Solaire Selectif FPSS) of Meudon Observatory is presently located at the focus of a solar refractor with a 28 cm lens directly pointed at the Sun. It produces a diffraction limited image without instrumental polarization and with a spectral resolution of 46,000 in a field of 6 arc min. diameter. The instrument is calibrated for absolute Doppler velocity measurements and is presently used for quantitative imagery of the radial velocity motions in the photosphere. The short period oscillations are recorded. Work of adapting the instrument for the imagery of the solar surface in the Stokes parameters is discussed. The first polarizer of the birefringent filter, with a reference position angle 0 deg, is associated with a fixed quarter wave plate at +45 deg. A rotating quarter wave plate is set at 0 deg and can be turned by incremented steps of exactly +45 deg. Another quarter wave plate also initially set at 0 deg is simultaneously incremented by -45 deg but only on each even step of the first plate. A complete cycle of increments produces images for each of the 6 parameters I + or - Q, I + or - U and I + or - V. These images are then subtracted by pairs to produce a full image in the three Stokes parameters Q, U and V. With proper retardation tolerance and positioning accuracy of the quarter wave plates, the cross talk between the Stokes parameters was calculated and checked to be minimal.

  2. 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.

  3. Induced birefringence and dichroism in azo polymers. Comparison between amorphous and liquid crystalline polymers

    SciTech Connect

    Natansohn, A.; Brown, D.; Rochon, P.

    1993-12-31

    Macroscopic order can be induced in amorphous high-Tg azo polymers (usually containing electron-donor - electron-acceptor substituted azobenzene moieties) by exposure to polarized light. The phenomenon is based on a series of trans-cis-trans isomerization cycles and the induced birefringence is typically of 2x10{sup {minus}2}. The ordered domains can be returned to randomness ({open_quotes}erased{close_quotes}) using circularly polarized light. This paper will present a comparison between amorphous and liquid crystalline azo polymers. The most significant difference between these two types of polymers is that any other type of concert with the azo moiety. Consequently the dichroism and birefringence induced in the liquid crystalline polymers can be one order of magnitude higher than in the amorphous polymers. At the same time, however, the time required to achieve saturation also increases by at least one order of magnitude.

  4. Compact real-time birefringent imaging spectrometer.

    PubMed

    Kudenov, Michael W; Dereniak, Eustace L

    2012-07-30

    The design and experimental demonstration of a snapshot hyperspectral imaging Fourier transform (SHIFT) spectrometer is presented. The sensor, which is based on a multiple-image FTS (MFTS), offers significant advantages over previous implementations using Michelson interferometers. Specifically, its use of birefringent interferometry creates a vibration insensitive and ultra-compact (15x15x10 mm(3)) common-path interferometer while offering rapid reconstruction rates through the graphics processing unit. The SHIFT spectrometer's theory and experimental prototype are described in detail. Included are reconstruction and spectral calibration procedures, followed by the spectrometer's validation using measurements of gas-discharge lamps. Lastly, outdoor measurements demonstrate the sensor's ability to resolve spectral signatures in typical outdoor lighting and environmental conditions. PMID:23038346

  5. Detection of birefringent microcrystals in bile

    DOEpatents

    Darrow, Chris; Mirhej, Andrew; Seger, Tino

    2003-09-30

    A transparent flow channel fluidly communicates a fluid source and a collection reservoir. A light beam passes through a first polarizer having a first plane of polarization. The flow channel is orthogonal to the light beam. The light beam passes through a fluid sample as it flows through the flow channel. The light beam is then filtered through a second polarizer having a second plane of polarization rotated 90.degree. from the first plane of polarization. The birefringence of certain crystalline materials present in the fluid sample rotates the plane of polarization of the light beam. The presence of these microcrystals thus causes a component of the beam to pass through the second polarizer and impinge an electronic photo-detector located in the path of the beam. The photo-detector signals the presence of the microcrystals by generating voltage pulses. A display device visually presents the quantitative results of the assay.

  6. Development of birefringent filters for spaceflight

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Pope, T. P.; Ramsey, H. E.; Schoolman, S. A.

    1976-01-01

    The critical problem for flight of a birefringent filter is the shock mounting of the calcite. The design presented here bonds the calcite block with silicon rubbers to the calcite holder. The calcite together with its all necessary polarizers and rotating achromatic plates are mounted together in units called a filter module. By using a set of modules containing calcite crystals of differing lengths, a filter can be produced. A description of the modules is given. Also described is a container for the filter modules, which can be used both to hermetically seal the system or contain an index matching oil. The response of a filter element while being controlled by the Lockheed Temperature Control is described and the determination of the wavelength sensitivity to temperature of calcite is explained. Operation of the filter using a software control algorithm instead of a hardware temperature controller is shown. Some radiation considerations of filter systems are given.

  7. Note: Ultra-low birefringence dodecagonal vacuum glass cell

    NASA Astrophysics Data System (ADS)

    Brakhane, Stefan; Alt, Wolfgang; Meschede, Dieter; Robens, Carsten; Moon, Geol; Alberti, Andrea

    2015-12-01

    We report on an ultra-low birefringence dodecagonal glass cell for ultra-high vacuum applications. The epoxy-bonded trapezoidal windows of the cell are made of SF57 glass, which exhibits a very low stress-induced birefringence. We characterize the birefringence Δn of each window with the cell under vacuum conditions, obtaining values around 10-8. After baking the cell at 150 °C, we reach a pressure below 10-10 mbar. In addition, each window is antireflection coated on both sides, which is highly desirable for quantum optics experiments and precision measurements.

  8. Integrated-optic polarization controllers incorporating polymer waveguide birefringence modulators.

    PubMed

    Kim, Jun-Whee; Park, Su-Hyun; Chu, Woo-Sung; Oh, Min-Cheol

    2012-05-21

    Polarization controllers based on polymer waveguide technology are demonstrated by incorporating thermo-optic birefringence modulators (BMs) and thin-film wave plates. Highly birefringent polymer materials are used to increase the efficiency of birefringence modulation in proportion to the heating power. Thin-film quarter-wave plates are fabricated by using a crosslinkable liquid crystal, reactive mesogen, and inserted between the BMs to produce static phase retardation and polarization coupling. By applying a triangular AC signal to one BM and a DC signal to another, the polarization states of the output light are modulated to cover the entire surface of the Poincaré sphere. PMID:22714231

  9. The Curie-Weiss behavior of birefringence in ferrofluids

    NASA Astrophysics Data System (ADS)

    Yusuf, N. A.; Abu-Safia, H.; Abu-Aljarayesh, I.

    1993-05-01

    Measurements of birefringence in an Fe3O4 magnetic fluid with isopar-M as a liquid carrier were undertaken as a function of temperature for 100birefringence increases with temperature exhibiting a maximum at a certain temperature Tm. The position of Tm decreases with increasing field intensity. For T≳Tm the birefringence follows a Curie-Weiss-type behavior. The ordering temperature changes not only in magnitude but also in sign with increasing field intensity, being negative for H≳500 Oe.

  10. Note: Ultra-low birefringence dodecagonal vacuum glass cell

    SciTech Connect

    Brakhane, Stefan Alt, Wolfgang; Meschede, Dieter; Robens, Carsten; Moon, Geol; Alberti, Andrea

    2015-12-15

    We report on an ultra-low birefringence dodecagonal glass cell for ultra-high vacuum applications. The epoxy-bonded trapezoidal windows of the cell are made of SF57 glass, which exhibits a very low stress-induced birefringence. We characterize the birefringence Δn of each window with the cell under vacuum conditions, obtaining values around 10{sup −8}. After baking the cell at 150 °C, we reach a pressure below 10{sup −10} mbar. In addition, each window is antireflection coated on both sides, which is highly desirable for quantum optics experiments and precision measurements.

  11. Photonic quasi-crystal fiber with high birefringence

    NASA Astrophysics Data System (ADS)

    Liu, Hongfei; Xiao, Wei; Cai, Weicheng; Liu, Exian; Feng, Bo; Wang, Ziming; Liang, Taiyuan; Wang, Shuo; Liu, Jianjun

    2016-03-01

    A high-birefringence photonic quasi-crystal fiber (HB-PQF) based on SiO2 is proposed. The relationships between birefringence and structure parameters and between beat length and structure parameters are researched by finite difference beam propagation method. With the optimization of fiber structure parameters, the birefringence is 1.4207×10-2, which is two orders of magnitude higher than the normally used fiber when the wavelength is 1.55 μm. The radius of the fiber is 6.5 μm. The HB-PQF in a communication sensor will have important application prospects.

  12. Novel laser machining of optical fibers for long cavities with low birefringence.

    PubMed

    Takahashi, Hiroki; Morphew, Jack; Oručević, Fedja; Noguchi, Atsushi; Kassa, Ezra; Keller, Matthias

    2014-12-15

    We present a novel method of machining optical fiber surfaces with a CO₂ laser for use in Fiber-based Fabry-Perot Cavities (FFPCs). Previously FFPCs were prone to large birefringence and limited to relatively short cavity lengths (≤ 200 μm). These characteristics hinder their use in some applications such as cavity quantum electrodynamics with trapped ions. We optimized the laser machining process to produce large, uniform surface structures. This enables the cavities to achieve high finesse even for long cavity lengths. By rotating the fibers around their axis during the laser machining process the asymmetry resulting from the laser's transverse mode profile is eliminated. Consequently we are able to fabricate fiber mirrors with a high degree of rotational symmetry, leading to remarkably low birefringence. Through measurements of the cavity finesse over a range of cavity lengths and the polarization dependence of the cavity linewidth, we confirmed the quality of the produced fiber mirrors for use in low-birefringence FFPCs. PMID:25607080

  13. Angular tuning of the magnetic birefringence in rippled cobalt films

    SciTech Connect

    Arranz, Miguel A.; Colino, José M.

    2015-06-22

    We report the measurement of magnetically induced birefringence in rippled Co films. For this purpose, the magneto-optical properties of ion beam eroded ferromagnetic films were studied using Kerr magnetometry and magnetic birefringence in the transmitted light intensity. Upon sufficient ion sculpting, these ripple surface nanostructures developed a defined uniaxial anisotropy in the in-plane magnetization, finely tuning the magnetic birefringence effect. We have studied its dependence on the relative orientation between the ripple direction and the magnetic field, and found this effect to be dramatically correlated with the capability to neatly distinguish the mechanisms for the in-plane magnetization reversal, i.e., rotation and nucleation. This double refraction corresponds univocally to the two magnetization axes, parallel and perpendicular to the ripples direction. We have also observed that tuned birefringence in stack assemblies of rippled Co films, which enables us to technically manipulate the number and direction of refraction axes.

  14. Luminescence from oriented emitting dipoles in a birefringent medium.

    PubMed

    Moon, Chang-Ki; Kim, Sei-Yong; Lee, Jeong-Hwan; Kim, Jang-Joo

    2015-04-01

    We present an optical model to describe the luminescence from oriented emitting dipoles in a birefringent medium and validate the theoretical model through its applications to a dye doped organic thin film and organic light emitting diodes (OLEDs). We demonstrate that the optical birefringence affects not only far-field radiation characteristics such as the angle-dependent emission spectrum and intensity from the thin film and OLEDs, but also the outcoupling efficiency of OLEDs. The orientation of emitting dipoles in a birefringent medium is successfully analyzed from the far-field radiation pattern of a thin film using the model. In addition, the birefringent model presented here provides a precise analysis of the angle-dependent EL spectra and efficiencies of OLEDs with the determined emitting dipole orientation. PMID:25968793

  15. Form birefringence in Kerr media: analytical formulation and rigorous theory.

    PubMed

    Bej, Subhajit; Tervo, Jani; Svirko, Yuri P; Turunen, Jari

    2015-06-15

    Employing the first-order effective medium theory, we develop an analytical model that governs light propagation inside a form birefringent medium with isotropic dielectric Kerr nonlinear material. This analytical model is found to be in excellent agreement with the recently developed rigorous Fourier modal method for Kerr nonlinear material [J. Opt. Soc. Am. B31, 2371 (2014)JOSAAH0030-394110.1364/JOSAB.31.002371]. Theoretical results demonstrate that form birefringent linear gratings with Kerr nonlinear materials behave like uniaxial crystals. However, the magnitude of birefringence can be tuned with a change of the incident light intensity. This paves the way toward all-optical control of form birefringence by exploiting optical nonlinearities in subwavelength structures. PMID:26076294

  16. Angular tuning of the magnetic birefringence in rippled cobalt films

    NASA Astrophysics Data System (ADS)

    Arranz, Miguel A.; Colino, José M.

    2015-06-01

    We report the measurement of magnetically induced birefringence in rippled Co films. For this purpose, the magneto-optical properties of ion beam eroded ferromagnetic films were studied using Kerr magnetometry and magnetic birefringence in the transmitted light intensity. Upon sufficient ion sculpting, these ripple surface nanostructures developed a defined uniaxial anisotropy in the in-plane magnetization, finely tuning the magnetic birefringence effect. We have studied its dependence on the relative orientation between the ripple direction and the magnetic field, and found this effect to be dramatically correlated with the capability to neatly distinguish the mechanisms for the in-plane magnetization reversal, i.e., rotation and nucleation. This double refraction corresponds univocally to the two magnetization axes, parallel and perpendicular to the ripples direction. We have also observed that tuned birefringence in stack assemblies of rippled Co films, which enables us to technically manipulate the number and direction of refraction axes.

  17. Anomalously temperature-independent birefringence in biaxial optical crystals

    SciTech Connect

    Grechin, Sergei G; Dmitriev, Valentin G; Dyakov, Vladimir A; Pryalkin, Vladimir I

    2000-01-31

    Temperature-independent birefringence in a biaxial crystal was predicted theoretically and observed experimentally for the first time. The width of the plot against temperature (the range corresponding to the temperature independence of the birefringence) at a fundamental radiation wavelength of 632.8 nm in a KTP crystal 5.9 mm long was more than 160{sup 0}C. (letters to the editor)

  18. Modulation instabilities in birefringent two-core optical fibres

    NASA Astrophysics Data System (ADS)

    Li, J. H.; Chiang, K. S.; Malomed, B. A.; Chow, K. W.

    2012-08-01

    Previous studies of the modulation instability (MI) of continuous waves (CWs) in a two-core fibre (TCF) did not consider effects caused by co-propagation of the two polarized modes in a TCF that possesses birefringence, such as cross-phase modulation (XPM), polarization-mode dispersion (PMD) and polarization-dependent coupling (PDC) between the cores. This paper reports an analysis of these effects on the MI by considering a linear-birefringence TCF and a circular-birefringence TCF, which feature different XPM coefficients. The analysis focuses on the MI of the asymmetric CW states in the TCFs, which have no counterparts in single-core fibres. We find that the asymmetric CW state exists when its total power exceeds a threshold (minimum) value, which is sensitive to the value of the XPM coefficient. We consider, in particular, a class of asymmetric CW states that admit analytical solutions. In the anomalous dispersion regime, without taking the PMD and PDC into account, the MI gain spectra of the birefringent TCF, if scaled by the threshold power, are almost identical to those of the zero-birefringence TCF. However, in the normal dispersion regime, the power-scaled MI gain spectra of the birefringent TCFs are distinctly different from their zero-birefringence counterparts, and the difference is particularly significant for the circular-birefringence TCF, which takes a larger XPM coefficient. On the other hand, the PMD and PDC only exert weak effects on the MI gain spectra. We also simulate the nonlinear evolution of the MI of the CW inputs in the TCFs and obtain good agreement with the analytical solutions.

  19. Form Birefringence in Thin Films with Oblique Columnar Structures

    NASA Astrophysics Data System (ADS)

    Wang, Jian-Guo; Shao, Jian-Da; Wang, Su-Mei; He, Hong-Bo; Fan, Zheng-Xiu

    2005-08-01

    Effective medium theory is useful for designing optical elements with form birefringent subwavelength structures. Thin films fabricated by oblique deposition are similar to the two-dimensional surface relief subwavelength gratings. We use the effective medium theory to calculate the anisotropic optical properties of the thin films with oblique columnar structures. The effective refractive indices and the directions are calculated from effective medium theory. It is shown that optical thin films with predetermined refractive indices and birefringence may be engineered.

  20. Time Circular Birefringence in Time-Dependent Magnetoelectric Media.

    PubMed

    Zhang, Ruo-Yang; Zhai, Yan-Wang; Lin, Shi-Rong; Zhao, Qing; Wen, Weijia; Ge, Mo-Lin

    2015-01-01

    Light traveling in time-dependent media has many extraordinary properties which can be utilized to convert frequency, achieve temporal cloaking, and simulate cosmological phenomena. In this paper, we focus on time-dependent axion-type magnetoelectric (ME) media, and prove that light in these media always has two degenerate modes with opposite circular polarizations corresponding to one wave vector , and name this effect "time circular birefringence" (TCB). By interchanging the status of space and time, the pair of TCB modes can appear simultaneously via "time refraction" and "time reflection" of a linear polarized incident wave at a time interface of ME media. The superposition of the two TCB modes causes the "time Faraday effect", namely the globally unified polarization axes rotate with time. A circularly polarized Gaussian pulse traversing a time interface is also studied. If the wave-vector spectrum of a pulse mainly concentrates in the non-traveling-wave band, the pulse will be trapped with nearly fixed center while its intensity will grow rapidly. In addition, we propose an experimental scheme of using molecular fluid with external time-varying electric and magnetic fields both parallel to the direction of light to realize these phenomena in practice. PMID:26329928

  1. Validating Laser-Induced Birefringence Theory with Plasma Interferometry

    SciTech Connect

    Chen, Cecilia

    2015-09-02

    Intense laser beams crossing paths in plasma is theorized to induce birefringence in the medium, resulting from density and refractive index modulations that affect the polarization of incoming light. The goal of the associated experiment, conducted on Janus at Lawrence Livermore’s Jupiter Laser Facility, was to create a tunable laser-plasma waveplate to verify the relationship between dephasing angle and beam intensity, plasma density, plasma temperature, and interaction length. Interferometry analysis of the plasma channel was performed to obtain a density map and to constrain temperature measured from Thomson scattering. Various analysis techniques, including Fast Fourier transform (FFT) and two variations of fringe-counting, were tried because interferograms captured in this experiment contained unusual features such as fringe discontinuity at channel edges, saddle points, and islands. The chosen method is flexible, semi-automated, and uses a fringe tracking algorithm on a reduced image of pre-traced synthetic fringes. Ultimately, a maximum dephasing angle of 49.6° was achieved using a 1200 μm interaction length, and the experimental results appear to agree with predictions.

  2. Comparison of birefringent electric split-ring resonator and meanderline structures as quarter-wave plates at terahertz frequencies.

    PubMed

    Strikwerda, Andrew C; Fan, Kebin; Tao, Hu; Pilon, Daniel V; Zhang, Xin; Averitt, Richard D

    2009-01-01

    We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The me-anderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 - 743 GHz, while the ELC achieves 99% from 626 - 660 GHz. However, both are broad enough for use with CW sources making ELCs a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70 microm for the meanderline structure and a mere 20 microm for the ELC highlighting the large degree of birefringence exhibited with metamaterial structures. PMID:19129881

  3. Birefringence gradient development during drying of solution cast functional films and their mechanical, optical and gas barrier properties

    NASA Astrophysics Data System (ADS)

    Yucel, Orcun

    shown by TEM images and WAXS. This is in agreement with the out-of-plane anisotropy development observed during drying. Beyond a critical solid wt%, out-of-plane birefringence started to increase earlier with organoclay addition. In the case of multi-layer organoclay reinforced PAI films, the drying behavior of each individual layer was tracked and a complementary drying model is proposed. Planar orientation of nanoplatelets resulted in excellent helium-barrier properties. Mechanical properties were optimized at 3wt% clay content. In a similar way, multifunctional nanocomposite films exhibiting flexibility, high modulus and high gas barrier properties were developed using a soluble polyamide-imide (PAI) in dimethylacetamide (DMAc) with graphene-oxide nanosheets (GO). Addition of GO content resulted in increase in evaporation rate of solvent. This was attributed to increase in hydrophobicity of the films with increased GO content as shown by contact angle measurements. Overall He permeability of dried hybrid films decreased over 40% even with very small GO content. Multi-layered optical retarder film exhibiting low birefringence dispersion and high optical clarity was developed using a solutions of polysulfone (PSF), polycarbonate-co-polymer (PCC) and atactic polystyrene (PS) in N-methyl pyrrolidone (NMP). The uniaxial and biaxial deformation behavior and associated anisotropy development were determined real-time, using a newly developed real-time measurement system. Higher deformation rates generated lower out-of-plane birefringence with higher in-plane birefringence. Machine Direction (MD) stretching resulted in negative retardation values at high deformation rates. This behavior was reversed upon inception of Transverse Direction (TD) stretching. Optimum R th and R0 values were achieved at 1mm/sec stretch rate to compensate ECB-LCDs. Birefringence dispersion of multi-layer films was found to be flattened.

  4. Laser Induced Birefringence in Pure Liquids

    NASA Astrophysics Data System (ADS)

    Harrison, Neil J.

    1991-01-01

    Available from UMI in association with The British Library. Laser induced birefringence or the Optical Kerr effect is a subject that has undergone much research over previous years and is an established technique for the study of many classes of materials. To date the measurements on various media have been characterized by the substantial time required to obtain results and the generally poor sensitivity of the apparatus used. This work describes the development of a new apparatus which is the first in the field to automate the signal capture and analysis utilizing a 1 Gigasample/second digitizing oscilloscope connected to a microcomputer to provide fast, accurate transient analysis. Careful design of the apparatus enabled operation at two inducing wavelengths of 532nm and 1064nm. The sensitivity and accuracy of the apparatus coupled with the rapid transient evaluation was tested on a number of well characterized samples including benzene, nitrobenzene, toluene and benzoyl chloride and was found to give excellent agreement with other workers. The apparatus was used to investigate the properties of the organic pure liquid series the n-alkanes before making the first measurements on the 1-alkenes, 1-alkynes, alcohols, carboxylic acids and three alkdienes. Results from these experiments were used to evaluate the contributions of sigma and pi bonds to the Optical Kerr effect in simple organic molecules. A review of all previously published Optical Kerr effect results for pure liquids was also carried out and the first comprehensive table of results complied.

  5. Polarization properties of fiber lasers with twist-induced circular birefringence

    SciTech Connect

    Kim, Ho Young; Lee, El Hang Kim, Byoung Yoon

    1997-09-01

    We have experimentally observed and theoretically analyzed the polarization properties of fiber lasers with twist-induced birefringence. Twisting a fiber induces the circular birefringence of a fiber laser cavity, and this birefringence reduces the effects of intrinsic linear birefringence on the polarization properties of fiber lasers. The frequencies of their polarization eigenmodes coincide with each other gradually as the twist rate increases, and the directions of polarization eigenmodes deviate from the birefringence axis at a much larger twist rate than the magnitude of intrinsic linear birefringence. We describe the successful experimental results for Nd and Er fiber lasers. {copyright} 1997 Optical Society of America

  6. Phase matching of four-wave interactions of SRS components in birefringent SRS-active crystals

    SciTech Connect

    Smetanin, Sergei N; Basiev, Tasoltan T

    2012-03-31

    A new method has been proposed for achieving wave vector matching in four-wave interactions of frequency components upon SRS in birefringent SRS-active crystals. The method ensures anti-Stokes wave generation and enables a substantial reduction in higher order Stokes SRS generation thresholds. Phase matching directions in BaWO{sub 4} SRS-active negative uniaxial crystals and SrWO{sub 4} SRS-active positive uniaxial crystals have been found in the wavelength range 0.4 - 0.7 {mu}m.

  7. Direct UV written planar Bragg gratings that feature zero fluence induced birefringence

    NASA Astrophysics Data System (ADS)

    Holmes, Christopher; Cooper, Peter A.; Fernando, Harendra N. J.; Stroll, Andreas; Gates, James C.; Krishnan, Chirenjeevi; Haynes, Roger; Mennea, Paolo L.; Carpenter, Lewis G.; Gawith, Corin B. E.; Roth, Martin M.; Charlton, Martin D.; Smith, Peter G. R.

    2015-12-01

    Direct UV writing is a planar fabrication process capable of simultaneously defining waveguides and Bragg gratings. The technique is fully computer controlled and uniquely uses a small focused spot ~7 μm in diameter for direct writing exposure. This work investigates its use to achieve phase trimming and Bragg grating definition in silica-on-silicon lithographic waveguides. It is observed that birefringence control using direct UV writing can be made independent of exposure fluence with this technique through tailoring substrate stress. The result is demonstrated experimentally and supported theoretically using finite element analysis.

  8. Dynamics of creation photoinduced birefringence on (PAH/PAZO)n layer-by-layer films: Analysis of consecutive cycles

    NASA Astrophysics Data System (ADS)

    Timóteo, Ana Rita Monteiro; Ribeiro, Jorge H. F.; Ribeiro, Paulo A.; Raposo, Maria

    2016-01-01

    Reproducibility and reliability of data is an important subject in the development of organic devices for photonics applications. This work reports the analysis of successive photoinduced birefringence creation curves in layer-by-layer films of poly(allylamine hydrochloride) (PAH) and poly{1-(4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido)-1,2-ethanediyl, sodium salt} (PAZO) with different number of bilayers. The birefringence creation or writing curves are described by two processes: a faster one referring the contribution of trans-cis-trans photoisomerization cycles to the birefringence; and a slower one associated to the contribution of motion of the polymer chain to the birefringence. As the number of write-erase cycles increases, the characteristic times of these processes decreases, respectively, to values of 18 and 212 s independently of the number of bilayers of films while for the magnitudes the fast process prevailed relatively to the slow, by 70% against 30%. The observed behavior is explained by the thermal treatment given by the laser beam in the irradiated area with increase of free volume which contributes for the chromophore mobility. This conclusion was achieved by measuring the surface temperature during and after irradiation and analyzing by optical microscopy the film surface where an increase of holes and aggregation as a result of irradiation was observed. Infrared spectra of films after and before irradiation showed changes in the Cdbnd C absorbance indicating aggregation of azobenzene groups while changes in the protonated and deprotonated carboxylic acid groups are consistent with ionization degree diminishing which is explained by the removal of water molecules by heating caused by laser. The results presented in this paper indicates that an increase in the number of write-erase cycles contributes to reliable and reproducible birefringence characteristics of PAH/PAZO films - a good new from point of view of possible applications.

  9. Birefringence and Enhanced Stability in Stable Organic Glasses

    NASA Astrophysics Data System (ADS)

    Liu, Tianyi; Exarhos, Annemarie; Cheng, Kevin; Jia, Tiezheng; Walsh, Patrick; Kikkawa, Jay; Fakhraai, Zahra

    Stable glasses can be prepared by physical vapor depositing organic molecules onto a cold substrate at slow rates. These glasses have many exceptional properties such as high thermal stability, high density, and birefringence. Regardless of the molecular shape or intermolecular interactions, birefringence has been observed in various stable glasses produced at low temperatures (below 80% of the molecule's glass transition temperature, Tg) . Here we prepare stable glasses of an organic molecule, 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene, that possesses a nearly isotropic shape and intrinsic fluorescence. Ellipsometry is used to show that all stable glasses prepared in the temperature range from 73% Tg to 97% Tgshow positive birefringence. Angle- and polarization- dependent photoluminescence measurements show isotropic molecular orientation in these optically birefringent glasses. Furthermore, the values of birefringence are strongly correlated with the enhanced density, implying a general origin of the observed anisotropy in stable glasses. This correlation can elucidate the role of packing in the formation of such high-density glasses. The authors would like to acknowledge Ethan Alguire and Joe Subotnik for simulation. Z.F. acknowledges funding from NSF CAREER (DMR-1350044). P.J.W. acknowledges funding from NSF (CHE-1152488). J.M.K acknowledges funding from NSF (DMR-1206270).

  10. Birefringence simulation of annealed ingot of calcium fluoride single crystal

    NASA Astrophysics Data System (ADS)

    Ogino, H.; Miyazaki, N.; Mabuchi, T.; Nawata, T.

    2008-01-01

    We developed a method for simulating birefringence of an annealed ingot of calcium fluoride single crystal caused by the residual stress after annealing process. The method comprises the heat conduction analysis that provides the temperature distribution during the ingot annealing, the elastic thermal stress analysis using the assumption of the stress-free temperature that provides the residual stress after annealing, and the birefringence analysis of an annealed ingot induced by the residual stress. The finite element method was applied to the heat conduction analysis and the elastic thermal stress analysis. In these analyses, the temperature dependence of material properties and the crystal anisotropy were taken into account. In the birefringence analysis, the photoelastic effect gives the change of refractive indices, from which the optical path difference in the annealed ingot is calculated by the Jones calculus. The relation between the Jones calculus and the approximate method using the stress components averaged along the optical path is discussed theoretically. It is found that the result of the approximate method agrees very well with that of the Jones calculus in birefringence analysis. The distribution pattern of the optical path difference in the annealed ingot obtained from the present birefringence calculation methods agrees reasonably well with that of the experiment. The calculated values also agree reasonably well with those of the experiment, when a stress-free temperature is adequately selected.

  11. Influence of birefringence splitting on ultrafast polarization oscillations in VCSELs

    NASA Astrophysics Data System (ADS)

    Lindemann, Markus; Gerhardt, Nils C.; Hofmann, Martin R.; Pusch, Tobias; Michalzik, Rainer

    2016-03-01

    Spin-VCSELs offer numerous advantages over conventional lasers like reduced threshold, spin amplification and ultrafast polarization dynamics. The latter have the potential to generate polarization modulation frequencies far above the conventional intensity relaxation oscillation frequency of one and the same device and thus can be an interesting basis for ultrafast optical data transmission. We have shown that fast polarization oscillations can be generated by pulsed spin injection. Furthermore the oscillation frequency can be tuned via modification of the VCSEL's cavity strain. Using this technique, oscillation frequencies with a tuning range from nearly zero up to 40 GHz can be demonstrated. In the device under study, this is more than six times the intensity relaxation oscillation frequency, which is nearly independent of the strain. Now we demonstrate the influence of the strain-induced birefringence splitting on the oscillation frequency. We find that the polarization oscillation frequency is directly corresponding to the birefringence splitting. The reason is that the polarization oscillates according to the beating frequency of the two orthogonal linearly polarized cavity modes in the VCSEL. In the case of spin-pumping, those two modes form the circular polarization output of the laser by superposition. Their frequencies are shifted by birefringence manipulation and form the basis of birefringence splitting. The measurement results are compared with simulations employing the spin-flip model. Our results show that high-frequency polarization oscillations can not only be generated with the help of external strain but with high birefringence splitting in general.

  12. Birefringence enhancement in annealed TiO2 thin films

    NASA Astrophysics Data System (ADS)

    van Popta, Andy C.; Cheng, June; Sit, Jeremy C.; Brett, Michael J.

    2007-07-01

    Postdeposition thermal annealing is used to enhance the form birefringence of nanostructured TiO2 thin films grown by electron-beam evaporation using the serial bideposition technique. Thin films were grown on fused silica substrates using oblique deposition angles between 60° and 75° and repetitive 180° substrate rotations to produce birefringent thin films that are structurally anisotropic. Postdeposition annealing in air, between 200 and 900°C, was used to increase the form birefringence of the films by changing the TiO2 phase from the as-deposited amorphous state to a polycrystalline state that exhibits a greater inherent density and larger bulk refractive index. The optical properties, microstructure, and crystallinity were characterized by Mueller matrix ellipsometry, scanning electron microscopy, atomic force microscopy, and x-ray diffraction. It was found that the in-plane birefringence increased significantly upon thermal annealing, in some cases yielding birefringence values that doubled in magnitude, from 0.11 to 0.22 at a wavelength of 550nm for films annealed at 400°C.

  13. Deposition, Characterization, And Simulation Of Thin Films With Form Birefringence

    NASA Astrophysics Data System (ADS)

    Jacobson, M. R.; Horowitz, F.; Liao, Bangjun

    1984-12-01

    Birefringence in optical thin films due to structure on a scale large compared to atoms but small compared to optical wavelengths, known as form birefringence (FB), was observed almost a century ago. More recently, studies of obliquely deposited metal films stimulated new interest in birefringent films. The link between structure, which is predominantly columnar in evaporated thin films, and birefringence has been conclusively demonstrated through ellipsometric measurement and modeling. Direct measurements of form birefringence are especially tedious in tilted films, since essentially four quantities must be derived: three indices of refraction and the film thickness. Clearly, four measurements are required; Horowitz' used an ellipsometric method to perform such measurements on a zirconium oxide (Zr02) film. Later, a 4.6-μm-thick film of Zr02 was obliquely deposited; spectrophotometric measurements revealed its utility as a half-wave plate. A parallel effort directed at understanding FB films through computer simulations has been undertaken by Sikkens and Liao. These simulations can be specialized to include defects, epitaxy, and anisotropic surface mobility. Applications of obliquely deposited FB films of familiar thin film materials can be anticipated if their structure and performance can be more thoroughly understood.

  14. Synthesis and surface modification of birefringent vaterite microspheres.

    PubMed

    Vogel, Robert; Persson, Martin; Feng, Chao; Parkin, Simon J; Nieminen, Timo A; Wood, Barry; Heckenberg, Norman R; Rubinsztein-Dunlop, Halina

    2009-10-01

    This paper reports on the synthesis of birefringent vaterite microspheres with narrow size distribution using a seeded growth method. In a post-treatment the microspheres were stabilized and functionalized through coating with a combination of organosilica and silica. The coating vastly enhanced the stability of the vaterite microspheres in biological buffers and allowed the attachment of biomolecules such as DNA or proteins. As an example, streptavidin was attached to the surface of the functionalized microspheres. These results pave the way for the use of birefringent vaterite particles for the micromanipulation of single biological molecules such as DNA or specific proteins in an optical trap capable of exerting and measuring torques. The stabilized birefringent microspheres may also find use for biosensor and biological screening applications. PMID:19788220

  15. Birefringent neutron prisms for spin echo scattering angle measurement

    NASA Astrophysics Data System (ADS)

    Pynn, Roger; Fitzsimmons, M. R.; Lee, W. T.; Stonaha, P.; Shah, V. R.; Washington, A. L.; Kirby, B. J.; Majkrzak, C. F.; Maranville, B. B.

    2009-09-01

    In the first decade of the 19th century, an English chemist, William Wollaston, invented an arrangement of birefringent prisms that splits a beam of light into two spatially separated beams with orthogonal polarizations. We have constructed similar devices for neutrons using triangular cross-section solenoids and employed them for Spin Echo Scattering Angle Measurement (SESAME). A key difference between birefringent neutron prisms and their optical analogues is that it is hard to embed the former in a medium which has absolutely no birefringence because this implies the removal of all magnetic fields. We have overcome this problem by using the symmetry properties of the Wollaston neutron prisms and of the overall spin echo arrangement. These symmetries cause a cancellation of Larmor phase aberrations and provide robust coding of neutron scattering angles with simple equipment.

  16. Plasmonic gold nanodiscs using piezoelectric substrate birefringence for liquid sensing

    NASA Astrophysics Data System (ADS)

    Hao, Danni; Kenney, Mitchell G.; Cumming, David R. S.

    2016-06-01

    This article presents the simulation, fabrication, and experimental characterization of a surface plasmonic resonance (SPR) sensor integrated with an acoustic sensing compatible substrate. The SPR sensor is designed to work in the visible region with gold nanodisc arrays fabricated on LiNbO3, which is both piezoelectric and birefringent. A linear relationship between resonance wavelength and varying liquid refractive indices were observed in experiments, and a sensitivity of 165 nm/refractive index unit was obtained. Polarization effects of the birefringent property of the Y-cut LiNbO3 substrate have been investigated, which can also be applied to X-cut LiNbO3. Our study demonstrates the feasibility of an SPR sensor device utilizing a birefringent substrate, which has acoustic wave compatibility and can pave the way toward much more robust and flexible biosensing devices.

  17. Distributed birefringence, strain and temperature measurement by homodyne BOTDR

    NASA Astrophysics Data System (ADS)

    Lu, Yuangang; Bao, Xiaoyi; Chen, Liang

    A novel distributed fiber birefringence, strain and temperature measurement based on homodyne Brillouin optical time domain reflectometry (BOTDR) is proposed. Birefringence measurement is based on the beat period detection of Brillouin beat of the same acoustic mode. Strain and temperature are obtained by measuring the power changes of Brillouin beat spectrum (BBS), which corresponds to the optical interaction of different acoustic modes in a complex profile fiber. The birefringence of a 4.3 km large-effective-area fiber (LEAF) was measured with 0.6-m spatial resolution, and strain and temperature at the end of a 4.5 km LEAF were measured at 1.5-m resolution in 140s.

  18. Mechanical phase matching of birefringent non-linear crystals.

    PubMed

    Deyra, Loïc; Balembois, François; Guilbaud, André; Villeval, Philippe; Georges, Patrick

    2014-09-22

    Second-order nonlinear processes such as second harmonic generation or parametric amplification have found numerous applications in the scientific and industrial world, from micromachining to petawatt laser facilities. These nonlinear interactions are mostly carried out in birefringent crystals because of their low cost and the possibility to operate at high powers Phase-matching configurations in birefringent crystals are determined by their refractive indexes. Here, we show that an important mechanical stress can be used to significantly change the phase-matching properties of a birefringent crystal. As an example, we demonstrate the shift of second harmonic non-critical phase matching wavelength of LiB3O5 (LBO) crystal at room temperature from 1200 nm to 1120 nm by applying compressive forces up to 100 MPa. We believe that this mechanical phase matching can be used as an additional degree of freedom to optimize nonlinear optical frequency mixing geometries. PMID:25321800

  19. Electric birefringence anomaly of solutions of ionically charged anisometric particles.

    PubMed

    Hoffmann, H; Gräbner, Dieter

    2015-02-01

    The term "electric birefringence anomaly" is known as the electric birefringence (EB) signal that occurs in solutions of ionically charged anisometric particles in a narrow concentration region. The signal is of opposite sign to the normal birefringence that occurs below and above this narrow concentration region. The normal electric birefringence signals in the dilute and more concentrated regions are due to the orientation of the particles in the direction of the applied electric field. The origin for the anomalous signal was not completely understood until now. The article summarises previous results in which the anomalous results had been observed but not well understood. It shows that the birefringence anomaly occurs in systems as diverse as micellar solutions, polyelectrolytes, solutions of clays, viruses and fibres. In all these systems the anomaly signals are present at the concentration when the length of the colloidal particles including the thickness of the electric double layer are about the same as the mean distance between the colloidal particles. Under these conditions the electric double layers of the particles overlap along the main axis of the particles but not in the direction across the particles. As a consequence of this situation a dipole is built up across the particles by the migration of the counter-ions of the particles in the electric field and this dipole leads to an orientation of the particles perpendicular to the electric field. The anomalous signal can usually be observed simultaneously with the normal signal. The amplitude of the anomalous signal can be larger than the amplitude of the normal signal. As a consequence the total birefringence changes its sign in the anomalous concentration region. The anomaly signal of the clays can also be explained by a fluctuating dipole around the particles, which is due to the fact that the centre of the ionic charges of the particles does not fall on the centre of the ionic charge of the counter

  20. Measurement of high-birefringent spun fiber parameters using short-length fiber Bragg gratings.

    PubMed

    Vasiliev, S A; Przhiyalkovsky, Ya V; Gnusin, P I; Medvedkov, O I; Dianov, E M

    2016-05-30

    Spectral polarization characteristics of short-length fiber Bragg gratings UV-written in a highly-birefringent spun-fiber have been investigated. Based on the analysis of the characteristics the technique for measuring the built-in linear phase birefringence as well as the spin period in this fiber type has been suggested. In this method the birefringence dispersion is excluded and therefore the built-in linear phase birefringence can be measured with an improved accuracy. PMID:27410060

  1. Photonic variable delay devices based on optical birefringence

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor)

    2005-01-01

    Optical variable delay devices for providing variable true time delay to multiple optical beams simultaneously. A ladder-structured variable delay device comprises multiple basic building blocks stacked on top of each other resembling a ladder. Each basic building block has two polarization beamsplitters and a polarization rotator array arranged to form a trihedron; Controlling an array element of the polarization rotator array causes a beam passing through the array element either going up to a basic building block above it or reflect back towards a block below it. The beams going higher on the ladder experience longer optical path delay. An index-switched optical variable delay device comprises of many birefringent crystal segments connected with one another, with a polarization rotator array sandwiched between any two adjacent crystal segments. An array element in the polarization rotator array controls the polarization state of a beam passing through the element, causing the beam experience different refractive indices or path delays in the following crystal segment. By independently control each element in each polarization rotator array, variable optical path delays of each beam can be achieved. Finally, an index-switched variable delay device and a ladder-structured variable device are cascaded to form a new device which combines the advantages of the two individual devices. This programmable optic device has the properties of high packing density, low loss, easy fabrication, and virtually infinite bandwidth. The device is inherently two dimensional and has a packing density exceeding 25 lines/cm2. The delay resolution of the device is on the order of a femtosecond (one micron in space) and the total delay exceeds 10 nanosecond. In addition, the delay is reversible so that the same delay device can be used for both antenna transmitting and receiving.

  2. Giant spatial-dispersion-induced birefringence in metamaterials

    NASA Astrophysics Data System (ADS)

    Gorlach, Maxim A.; Glybovski, Stanislav B.; Hurshkainen, Anna A.; Belov, Pavel A.

    2016-05-01

    We demonstrate experimentally giant spatial-dispersion-induced birefringence in metamaterials. The difference between the reflection coefficients for (1 ,1 ¯,0 ) - and (0 ,0 ,1 ) -polarized light reflected from the [1 ,1 ,0 ] surface of a metamaterial reaches 78 % . The magnitude of spatial-dispersion-induced birefringence in the transparency windows of the structure reaches n1 1 ¯0-n001=-0.13 , which is at least three orders of magnitude larger than the typical values reported for natural crystals. Our results elucidate the important role of spatial dispersion effects in a wide class of metamaterials.

  3. Birefringent reflectarray metasurface for beam engineering in infrared.

    PubMed

    Farmahini-Farahani, Mohsen; Mosallaei, Hossein

    2013-02-15

    An infrared reflectarray metasurface with engineered birefringent behavior is demonstrated. The array reradiates incoming light into two orthogonal, linearly polarized reflections. The reflectarray is composed of rectangular metallic patch nanoantennas placed on top of a grounded dielectric stand-off layer. The patches are designed to locally manipulate the phase front of the incoming wave. They tailor the reflection phase to transform the phase front on the surface to the one desired for both orthogonal polarizations at the same time. The proposed nanoantenna metasurface can find applications in many optical devices, such as birefringent modulators, waveplates, polarizers, and splitters. PMID:23455103

  4. Mirror Birefringence in a Fabry-Perot Cavity and the Detection of Vacuum Birefringence in a Magnetic Field

    NASA Technical Reports Server (NTRS)

    Chui, T. C. P.; Shao, M.; Redding, D.; Gursel, Y.; Boden, A.

    1995-01-01

    We discuss the effect of mirror birefringence in two optical schemes designed to detect the quantum-electrodynamics (QED) predictions of vacuum birefringence under the influence of a strong magnetic field, B. Both schemes make use of a high finesse Fabry-Perot cavity (F-P) to increase the average path length of the light in the magnetic field. The first scheme, which we called the frequency scheme, is based on measurement of the beat frequency of two orthogonal polarized laser beams in the cavity. We show that mirror birefringence contributes to the detection uncertainties in first order, resulting in a high susceptibility to small thermal disturbances. We estimate that an unreasonably high thermal stability of 10-9 K is required to resolve the effect to 0.1%. In the second scheme, which we called the polarization rotation scheme, laser polarized at 45 relative to the B field is injected into the cavity.

  5. Temporal laser pulse shaping for RF photocathode guns : the cheap and easy way using UV birefringent crystals.

    SciTech Connect

    Power, J. G.; Jing, C.; High Energy Physics; Euclid Techlabs, LLC

    2009-01-01

    We report experimental investigations into a new technique for achieving temporal laser pulse shaping for RF photocathode gun applications using inexpensive UV birefringent crystals. Exploiting the group velocity mismatch between the two different polarizations of a birefringent crystal, a stack of UV pulses can be assembled into the desired temporal pulse shape. The scheme is capable of generating a variety of temporal pulse shapes including: (i) flat-top pulses with fast rise-time and variable pulse duration. (ii) microbunch trains, and (iii) ramped pulse generation. We will consider two applications for beam generation at the Argonne Wakefield Accelerator (AWA) including a flat-top laser pulse for low emittance production and matched bunch length for enhanced transformer ratio production. Streak camera measurements of the temporal profiles generated with a 2-crystal set and a 4-crystal set are presented.

  6. Electrically switchable polymer liquid crystal and polymer birefringent flake in fluid host systems and optical devices utilizing same

    SciTech Connect

    Marshall, Kenneth L.; Kosc, Tanya Z.; Jacobs, Stephen D.; Faris, Sadeg M.; Li, Le

    2003-12-16

    Flakes or platelets of polymer liquid crystals (PLC) or other birefringent polymers (BP) suspended in a fluid host medium constitute a system that can function as the active element in an electrically switchable optical device when the suspension is either contained between a pair of rigid substrates bearing transparent conductive coatings or dispersed as microcapsules within the body of a flexible host polymer. Optical properties of these flake materials include large effective optical path length, different polarization states and high angular sensitivity in their selective reflection or birefringence. The flakes or platelets of these devices need only a 3-20.degree. rotation about the normal to the cell surface to achieve switching characteristics obtainable with prior devices using particle rotation or translation.

  7. Temporal Laser Pulse Shaping for RF Photocathode Guns: The Cheap and Easy way using UV Birefringent Crystals

    SciTech Connect

    Power, John G.; Jing Chunguang

    2009-01-22

    We report experimental investigations into a new technique for achieving temporal laser pulse shaping for RF photocathode gun applications using inexpensive UV birefringent crystals. Exploiting the group velocity mismatch between the two different polarizations of a birefringent crystal, a stack of UV pulses can be assembled into the desired temporal pulse shape. The scheme is capable of generating a variety of temporal pulse shapes including: (i) flat-top pulses with fast rise-time and variable pulse duration. (ii) microbunch trains, and (iii) ramped pulse generation. We will consider two applications for beam generation at the Argonne Wakefield Accelerator (AWA) including a flat-top laser pulse for low emittance production and matched bunch length for enhanced transformer ratio production. Streak camera measurements of the temporal profiles generated with a 2-crystal set and a 4-crystal set are presented.

  8. A Kind of Double-Cladding Photonic Crystal Fiber with High Birefringence and Two Zero-Dispersion Wavelengths

    NASA Astrophysics Data System (ADS)

    Zhou, Hong-Song; Li, Shu-Guang; Fu, Bo; Yao, Yan-Yan; Zhang, Lei

    2010-01-01

    A kind of double-cladding photonic crystal fiber (DC-PCF) with high birefringence and two zero-dispersion wavelengths is proposed. It is found that the birefringence of DC-PCF with inner cladding air holes pitch 1.0 μm and diameter 0.8 μm is 1.001 × 10-2 in the optical communication band at wavelength 1.55 μm by the multipole method. It is demonstrated that two zero dispersion wavelengths can be achieved in the optical communication band between 0.8 μm and 1.7 μm, and the first zero-dispersion wavelength is in the working wave band of the Ti:sapphire oscillator, which contributes to the frequency conversion of the Ti:sapphire femtosecond laser. PCF with two zero-dispersion wavelengths can make strong power supercontinuum spectral in the near infrared band.

  9. Numerical simulation of laser focusing properties inside birefringent crystal.

    PubMed

    Deng, Leimin; Liu, Peng; Duan, Jun; Zeng, Xiaoyan; Wu, Baoye; Wang, Xizhao

    2016-02-01

    The transmission properties of a focused laser inside anisotropic material are complex due to the birefringent effect, which has remarkable influence on the light distribution and frequency multiplication efficiency of crystals. Meanwhile, it will also affect the laser micromachining precision of birefringent materials with random polarization. In this study, ray tracing and diffraction integral methods were proposed to develop the mathematical model of a laser focused through an isotropic medium into a KDP crystal. Using these models, the focusing properties and 3D light intensity distribution of a focused laser inside a KDP crystal at different orientations were investigated. The research shows that the size and shape of the E-ray focus will distort, and its peak power density decreases rapidly with the decrease of the angle between the optical axis and the crystal surface. Meanwhile, the focal position of the E-ray will also move with the change of optical axis orientation. Based on the simulated results, an approximate 3D light intensity equation of a laser focused into birefringent material was also proposed, which is in good agreement with the theoretical analysis. The related simulated results have an important engineering value for nonlinear optics and laser processing of birefringent materials. PMID:26836091

  10. Fabrication of Multi-Ply Birefringent Fibrous Composite Laminates

    NASA Technical Reports Server (NTRS)

    Daniel, I.; Niiro, T.

    1984-01-01

    Fabrication method produces unidirectional, multi-ply, transparent birefringent fibrous composite laminates for use in macromechanical stress analysis conducted by means of anisotropic photoelasticity. New laminates glass-fiber-reinforced plastics for which matrix and fibers have same index of refraction. Method utilized in structural applications of composites.

  11. Sprayable birefringent coating enables strain measurements on large surfaces

    NASA Technical Reports Server (NTRS)

    Humphrey, F. T.; Mcgee, W. M.

    1966-01-01

    Birefringent coating for strain measurements on large surfaces contains constituents that can be premixed and sprayed as a single component with conventional paint spray equipment. Elevated temperatures are not required for spraying or curing of the coating material which has long pot life.

  12. Birefringence of the antiferromagnetic crystals linear in a magnetic field

    NASA Astrophysics Data System (ADS)

    Eremenko, V. V.; Kharchenko, N. F.; Beliy, L. I.; Tutakina, O. P.

    1980-01-01

    The new linear magneto-optical effect-birefringence-of a linear polarized light which is directly proportional to the magnetic field strength has been observed. This effect is permitted in crystals which allow piezo-magnetic properties. One was studied in antiferromagnet CoF 2 and CoCO 3 for the longitudinal geometry of an experiment.

  13. Chirped optical solitons in single-mode birefringent fibers

    NASA Astrophysics Data System (ADS)

    Mahmood, M. F.

    1996-12-01

    The trapping behavior of two chirped solitons forming a bound state in a single-mode birefringent fiber is investigated on the basis of a model of coupled nonlinear Schroedinger equations. The positive initial chirp plays an important role in controlling the threshold amplitude for soliton trapping without causing excessive pulse broadening.

  14. Zero-birefringent polyimide for polymer optical waveguide

    NASA Astrophysics Data System (ADS)

    Baek, Sung-Ho; Kang, Jae-Wook; Li, Xiangdan; Lee, Myong-Hoon; Kim, Jang-Joo

    2003-07-01

    A novel zero birefringent and photosensitive polyimide was synthesized. The polymer is soluble in solvents and contains a chalcone group for photo-crosslinking by UV exposure. The glass transition and decomposition temperature of the polymer were 254°C and 430°C before cross-linking. Evolution of the absorption spectra upon UV exposure indicated that the cross-linking reaction is related to the cycloaddition of the double bonds in the chalcone group to form cyclobutane. The photo-crosslinking reaction not only increased the thermal stability, but also induced a refractive index change of the films. The refractive index of the film was reduced upon UV exposure from 1.5862 to 1.5697 for TE mode and from 1.5807 to 1.5697 for TM mode, respectively, resulting in zero birefringence after curing. Loss of p-conjugation in the chalcone group by the crosslinking reaction is supposed to induce the reduction of the refractive indices and orbital change from sp2 to sp3 makes the polymer chain be kinked, resulting in decrease of birefringence. The polymer film showed optical loss of 0.41 dB/cm at 1.3 mm and 0.54 dB/cm at 1.55 mm. Zero birefringence and low optical loss combined with photo-processibility of the material are making it an excellent candidate for the high performance waveguide materials.

  15. Dispersion characterization of group birefringence in polarization-maintaining fiber using a Kerr phase-interrogator

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Baker, Chams; Bao, Xiaoyi

    2015-07-01

    We present a new approach to characterize dispersion of group birefringence in a long polarization-maintaining fiber (PMF). Two sinusoidal optical signals are respectively launched into fast and slow axes of a PMF under test. Wavelength dependent group-delay difference between two sinusoidal optical signals induced by group birefringence in the PMF is measured using a Kerr phase-interrogator, and dispersion of group birefringence is characterized from the group-delay difference. Measurements of wavelength dependent group birefringence and group birefringence dispersion for a 459.4-m Panda PMF are experimentally demonstrated.

  16. Large Flow-Birefringence of Nematogenic Bent-Core Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Bailey, Christopher; Fodor-Csorba, Katalin; Verduzco, Rafael; Gleeson, James; Sprunt, Samuel; Jakli, Antal

    2009-03-01

    We have found that bent-core liquid crystalline materials show exceptionally large flow birefringence in their isotropic liquid phase. The flow birefringence is over two orders of magnitude larger than usual for low molecular weight liquid crystals. Comparing the flow birefringence per unit viscosity, the observed values are an order of magnitude larger than low molecular weight and side-chain polymeric calamitic liquid crystals. This large flow birefringence is attributed to the nanostructure of these materials that contain temporary smectic clusters of a few smectic layers, which exist even in their isotropic phase. These smectic clusters appear to shear align resulting in the observed flow birefringence behavior.

  17. Detecting axial heterogeneity of birefringence in layered turbid media using polarized light imaging

    PubMed Central

    Alali, Sanaz; Wang, Yuting; Vitkin, I. Alex

    2012-01-01

    The structural anisotropy of biological tissues can be quantified using polarized light imaging in terms of birefringence; however, birefringence varies axially in anisotropic layered tissues. This may present ambiguity in result interpretation for techniques whose birefringence results are averaged over the sampling volume. To explore this issue, we extended the polarization sensitive Monte Carlo code to model bi-layered turbid media with varying uniaxial birefringence in the two layers. Our findings demonstrate that the asymmetry degree (ASD) between the off-diagonal Mueller matrix elements of heterogeneously birefringent samples is higher than the homogenously birefringent (uniaxial) samples with the same effective retardance (magnitude and orientation). We experimentally verified the validity of ASD as a birefringence heterogeneity measure by performing polarized light measurements of bi-layered elastic and scattering polyacrylamide phantoms. PMID:23243575

  18. Electrical induction and optical erasure of birefringence in the isotropic liquid phase of a dichiral azobenzene liquid-crystalline compound (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Yamamoto, Takahiro; Nishiyama, Isa

    2015-10-01

    Liquid crystal is a representative soft matter, which has physical properties between those of conventional liquid and those of crystal in a temperature range above a melting point. A liquid-crystal display (LCD) employs the response of the liquid-crystal alignment to the electric field and is a key device of an information display. For common LCDs, the precise control of the initial alignment of LC molecules is needed so that a good dark state, thus a high contrast ratio, can be obtained. If the birefringence can be induced in the liquid phase by the application of electric field, it is of great use as a material for the LCD application. In this study, we will report a unique property of dichiral azobenzene liquid crystals: an electric induction of birefringence in a liquid phase of an antiferroelectric dichiral azobenzene liquid crystal. The optically isotropic texture changes into the homogenous birefringent texture by the application of the in-plane electric field above the clearing temperature of the liquid crystal. We find that one of the possible reasons of the induction of the birefringence in the isotropic phase is the electrically-induced increase of the phase transition temperature between the antiferroelectric liquid-crystalline and "liquid" phases, i.e., increase in the clearing temperature. The resulting birefringence can be disappeared by the irradiation of UV light, due to the photoinduced isomerization of the azobenzene compound, thus dual control of the birefringent structure, by the irradiation of light and/or by the application of the electric field, is achieved.

  19. Development of an angular displacement measurement technique through birefringence heterodyne interferometry.

    PubMed

    Hsieh, Hung-Lin; Lee, Ju-Yi; Chen, Lin-Yu; Yang, Yang

    2016-04-01

    An angular displacement measurement sensor with high resolution for large range measurement is presented. The design concept of the proposed method is based on the birefringence effect and phase detection of heterodyne interferometry. High system symmetry and simple operation can be easily achieved by employing an innovative sandwich optical design for the angular sensor. To evaluate the feasibility and performance of the proposed method, several experiments were performed. The experimental results demonstrate that our angular displacement measurement sensor can achieve a measurement range greater than 26°. Considering the high-frequency noise, the measurement resolution of the system is approximately 1.2° × 10-4. Because of the common-path arrangement, our proposed method can provide superior immunity against environmental disturbances. PMID:27136979

  20. Annealing of linear birefringence in single-mode fiber coils - Application to optical fiber current sensors

    NASA Technical Reports Server (NTRS)

    Tang, Dingding; Rose, A. H.; Day, G. W.; Etzel, Shelley M.

    1991-01-01

    Annealing procedures that greatly reduce linear birefringence in single-mode fiber coils are described. These procedures have been successfully applied to coils ranging from 5 mm to 10 cm in diameter and up to 200 or more turns. They involve temperature cycles that last 3-4 days and reach maximum temperatures of about 850 C. The residual birefringence and induced loss are minimized by proper selection of fiber. The primary application of these coils is optical fiber current sensors, where they yield small sensors that are more stable than those achieved by other techniques. A current sensor with a temperature stability of 8.4 x 10 to the -5th/K over the range from -75 to 145 C has been demonstrated. This is approximately 20 percent greater than the temperature dependence of the Verdet constant. Packaging degrades the stability, but a packaged sensor coil with a temperature stability of about 1.6 + 10 to the -4th/K over the range from -20 to 120 C has also been demonstrated.

  1. Optical activity of a single MnAs cluster: Birefringence or Kerr effect

    NASA Astrophysics Data System (ADS)

    Leuschner, M.; Klar, P. J.; Heimbrodt, W.; Rühle, W. W.; Hara, S.; Stolz, W.; Volz, K.; Kurz, T.; Loidl, A.; Krug von Nidda, H.-A.

    2006-06-01

    We have grown In 0.54Ga 0.46As:Mn/MnAs granular paramagnetic-ferromagnetic hybrid structures by metal-organic vapor-phase epitaxy. The MnAs clusters have a Curie temperature of about 320 K. We have studied the optical activity of individual ferromagnetic MnAs clusters embedded in the paramagnetic In 0.54Ga 0.46As:Mn matrix at room temperature by far-field depolarization measurements. A scanning near-field optical microscopy set-up in constant height mode ( ≈100 nm above the sample surface) was used to achieve a high spatial resolution. Individual MnAs clusters rotate the linear polarization of the incoming light by almost 2∘ in this reflection geometry. This optical activity was analyzed in terms of birefringence and polar Kerr effect and correlated with the structural and magnetic properties of the MnAs clusters as determined by ferromagnetic resonance measurements. The optical activity of the MnAs clusters turns out to be dominated by linear birefringence caused by the uniaxial symmetry of the hexagonal crystal structure of MnAs. The polar Kerr effect plays a minor role in this experiment.

  2. A scatterometry based CD metrology solution for advanced nodes, including capability of handling birefringent layers with uniaxial anisotropy

    NASA Astrophysics Data System (ADS)

    Ke, Chih-Ming; Hu, Jimmy; Wang, Willie; Huang, Jacky; Chung, H. L.; Liang, C. R.; Shih, Victor; Liu, H. H.; Lee, H. J.; Lin, John; Fan, Y. D.; Yen, Tony; Wright, Noelle; Alvarez Sanchez, Ruben; Coene, Wim; Noot, Marc; Yuan, Kiwi; Wang, Vivien; Bhattacharyya, Kaustuve; van der Mast, Karel

    2009-03-01

    A brand new CD metrology technique that can address the need for accuracy, precision and speed in near future lithography is probably one of the most challenging items. CDSEMs have served this need for a long time, however, a change of or an addition to this traditional approach is inevitable as the increase in the need for better precision (tight CDU budget) and speed (driven by the demand for increase in sampling) continues to drive the need for advanced nodes. The success of CD measurement with scatterometry remains in the capability to model the resist grating, such as, CD and shape (side wall angle), as well as the under-lying layers (thickness and material property). Things are relatively easier for the cases with isotropic under-lying layers (that consists of single refractive or absorption indices). However, a real challenge to such a technique becomes evident when one or more of the under-lying layers are anisotropic. In this technical presentation the authors would like to evaluate such CD reconstruction technology, a new scatterometry based platform under development at ASML, which can handle bi-refringent non-patterned layers with uniaxial anisotropy in the underlying stack. In the RCWA code for the bi-refringent case, the elegant formalism of the enhanced transmittance matrix can still be used. In this paper, measurement methods and data will be discussed from several complex production stacks (layers). With inclusion of the bi-refringent modeling, the in-plane and perpendicular n and k values can be treated as floating parameters for the bi-refringent layer, so that very robust CD-reconstruction is achieved with low reconstruction residuals. As a function of position over the wafer, significant variations of the perpendicular n and k values are observed, with a typical radial fingerprint on the wafer, whereas the variations in the in-plane n and k values are seen to be considerably lower.

  3. Influence of birefringence in the instability spectra of oppositely directed coupler with negative index material channel

    NASA Astrophysics Data System (ADS)

    Shafeeque Ali, A. K.; Nithyanandan, K.; Porsezian, K.; Maimistov, Andrei I.

    2016-02-01

    A theoretical investigation on the influence of birefringence in the modulational instability (MI) spectra of an oppositely directed coupler (ODC) with a negative index material (NIM) channel is presented. We study the effect of birefringence on MI in linear and circular birefringent ODCs for both normal and anomalous dispersion regimes. It is found that besides the instability band due to nonlinear positive index material (PIM) and negative index material (NIM) channels, new symmetric instability regions are observed as a result of birefringent effects. Also defocusing nonlinearity suppresses the NIM band in the normal dispersion regime, but in the anomalous dispersion regime the defocusing nonlinearity enhances the gain of the NIM band. In contrast to the case of linear birefringence, in terms of MI gain from circular birefringence, only two birefringent bands dominate: the inherently PIM and NIM bands. This preponderance is attributed to the fact that the cross-phase modulation effect for the case of circular birefringence is stronger, thus allowing a better coupling between the beams, which results in the enhancement of the gain. Therefore, the manipulation of MI and solitons in an ODC is better performed when the birefringence is circular rather than linear. Here we report how to generate and manipulate MI and solitons in birefringent ODCs with a particular emphasis on a NIM channel.

  4. Birefringence Measurements of Spherulites formed in β-Lactoglobulin

    NASA Astrophysics Data System (ADS)

    Hardin, Eric; Kirkwood, Brad; Loman, Jazmine; Herat, Athula; Mahmood, Rizwan; Domike, Kristin

    2009-03-01

    Many proteins have a propensity to aggregate into amyloid fibril containing spherulite-like structures. In some instances these spherulitic protein aggregates have been observed in people suffering from a number of neurodegenerative diseases, including Alzheimer's, Parkinson's, and Creutzfeldt-Jakob's. However, the exact role these aggregates play in the body, their internal structure, and the aggregation mechanism still remains a mystery. The model protein used in our study, β-lactoglobulin (BLG), produce spherulites under low pH and high temperature conditions. We report birefringence measurement on BLG using phase retardation method as a function of temperature. Birefringence (˜0.0022 ± 0.0002) data suggest very weak ordering within the spherulites. These spherulites seem to disappear when we added an extensively studied thermotropic liquid crystal [4'-pentyl-4-cyanobiphenyl (5CB)] in β-Lactoglobulin + water+ hydrochloric acid. Our preliminary data suggests that the strong interaction energy between the two systems may lead to the destruction of spherulites.

  5. Ultraviolet-induced birefringence in hydrogen-loaded optical fiber

    SciTech Connect

    Canning, J.; Deyerl, H.J.; Soerensen, H.R.; Kristensen, M.

    2005-03-01

    A precision phase-shifting approach to fabricate various phase-shifted gratings using different combinations of polarized ultraviolet (UV) light is demonstrated. In doing so, the difference between s- and p-polarized light reported by others is confirmed. However, we reveal added complexity for the role of hydrogen and deuterium in the UV-induced process. Previous arguments for the origins are systematically ruled out by reviewing existing literature. We note that the birefringence is made up of at least two components with different thermal stabilities, one consistent simply with molecular hydrogen being present in the system. Overall the birefringence, by deduction, is associated with anisotropy in hydrogen reactions within the fiber. As a result they lead, through known mechanisms of dilation in glass, to anisotropic stress relaxation that can be annealed out, with or without hydrogen remaining, at low temperatures close to 125 deg. C.

  6. Dichroism and birefringence of natural violet diamond crystals

    SciTech Connect

    Konstantinova, A. F. Titkov, S. V.; Imangazieva, K. B.; Evdishchenko, E. A.; Sergeev, A. M.; Zudin, N. G.; Orekhova, V. P.

    2006-05-15

    Investigation of the optical properties of natural violet diamonds from the Yakutian kimberlites is performed. A red shift of the absorption edge is revealed in the absorption spectra of these crystals. This shift is indicative of the presence of a high concentration of nitrogen in the diamonds studied. Along with the strong band at 0.550 {mu}m, weaker bands at 0.390, 0.456 and 0.496 {mu}m are revealed. It is shown that violet diamond crystals have birefringence and dichroism of about 10{sup -5} and 10{sup -6}, respectively. When a light beam propagates perpendicularly to colored lamellas, the dichroism is much larger and the birefringence is smaller than in the case where the beam direction is parallel to lamellas.

  7. Large Flow Birefringence of Nematogenic Bent-Core Liquid Crystals

    SciTech Connect

    Bailey, C.; Fodor-Csorba, K; Verduzco, R; Gleeson, J; Sprunt, S; Jakli, A

    2009-01-01

    We have found that bent-core liquid crystalline materials show exceptionally large intrinsic flow birefringence in their isotropic liquid phase. This effect is more than 100 times larger than typical values measured for low molecular weight liquid crystals. The specific flow birefringence (i.e., normalized by the flow viscosity) is an order of magnitude larger than in both side-chain polymeric as well as low molecular weight liquid crystals. We propose that this large enhancement for bent-core compounds may be attributed to nanoscale smecticlike clusters that persist above the nematic-isotropic transition temperature, and shear align under shear flow; however, this mechanism has not yet been definitively confirmed.

  8. Reducing Birefringence Uncertainty in the Design of ATST Polarization Components

    NASA Astrophysics Data System (ADS)

    Sueoka, S. R.

    2014-10-01

    Scientific requirements for the Advanced Technology Solar Telescope push the limits of polarimetric calibration and modulation components. The super achromatic retarder and poly chromatic modulator designs comprise of a stack of wave plates with fast axes at different orientations. In order to design these elements over a broad wavelength range it is imperative to know the fundamental properties of the materials. Crystalline quartz, sapphire, and MgF2 have been selected as candidate materials due to their hardness, transmission, and unique birefringence properties. Previously published dispersion models for these crystals do not agree in areas of the design wavelength range. We performed a series of measurements to determine the birefringence from 0.38 μm to 5.0 μm in order to improve our design capabilities.

  9. Tuning micropillar cavity birefringence by laser induced surface defects

    SciTech Connect

    Bonato, Cristian; Ding Dapeng; Gudat, Jan; Exter, Martin P. van; Thon, Susanna; Kim, Hyochul; Petroff, Pierre M.; Bouwmeester, Dirk

    2009-12-21

    We demonstrate a technique to tune the optical properties of micropillar cavities by creating small defects on the sample surface near the cavity region with an intense focused laser beam. Such defects modify strain in the structure, changing the birefringence in a controllable way. We apply the technique to make the fundamental cavity mode polarization-degenerate and to fine tune the overall mode frequencies, as needed for applications in quantum information science.

  10. Use of Cosserat birefringence to measurement couple stresses by photoelasticity

    SciTech Connect

    Marek, Sikoń

    2014-05-27

    The quantum analysis of the polar atom under the action of a mechanical load is presented in this work. The obtained solution can be used to describe the optical properties of the Cosserat medium in the form of the gyro-birefringence. Rayleigh scattering of laser light coming towards the Cosserat medium head is analysed to measure the rotation of the azimuth of polarisation associated with couple stresses.

  11. Spectral-Content Readout Of Stress-Induced Birefringence

    NASA Technical Reports Server (NTRS)

    Redner, Alex S.; Voloshin, Arkady S.

    1992-01-01

    Spectrum of transmitted light indicates stress in sensor or specimen. Photoelastic apparatus demonstrates feasibility of analysis of spectrum of transmitted light to quantify birefringence in transparent specimen. By augmenting conventional photoelastic analysis with spectral sensors and automating it with computer control and processing of data, technique made more versatile and useful. Potential uses include measurement of stresses in optical fibers and transparent materials in general.

  12. Fourier polarimetry of the birefringence distribution of myocardium tissue

    NASA Astrophysics Data System (ADS)

    Ushenko, O. G.; Dubolazov, O. V.; Ushenko, V. O.; Gorsky, M. P.; Soltys, I. V.; Olar, O. V.

    2015-11-01

    The results of optical modeling of biological tissues polycrystalline multilayer networks have been presented. Algorithms of reconstruction of parameter distributions were determined that describe the linear and circular birefringence. For the separation of the manifestations of these mechanisms we propose a method of space-frequency filtering. Criteria for differentiation of causes of death due to coronary heart disease (CHD) and acute coronary insufficiency (ACI) were found.

  13. Leaky Dyakonov surface plasmon polaritons for birefringent crystals

    NASA Astrophysics Data System (ADS)

    Loot, Ardi; Hizhnyakov, Vladimir

    2016-04-01

    The surface waves propagating at the interface of a metal-birefringent crystal, usually called Dyakonov surface plasmon polaritons (DSPPs), have been theoretically investigated. It was shown that at special conditions the extraordinarily polarized component of DSPPs could become leaky. The properties of such half-leaky waves were theoretically investigated, and it was shown that these surface waves could be excited without any prism or grating. This is especially beneficial in the experiments of nonlinear optics where a field enhancement is required.

  14. Diffraction properties of highly birefringent liquid-crystal composite gratings.

    PubMed

    Butler, J J; Malcuit, M S

    2000-03-15

    We have fabricated electrically switchable holographic gratings, using Polaroid Corporation's DMP-128 photopolymer filled with the nematic liquid crystal E7. It is shown that a coupled-wave theory that includes the effects of the birefringence of the liquid crystal must be used to explain the diffraction properties of these anisotropic volume gratings. Furthermore, a detailed comparison of theory and experiment provides information about the alignment of the liquid crystal within the polymer host. PMID:18059899

  15. POLARBEAR constraints on cosmic birefringence and primordial magnetic fields

    NASA Astrophysics Data System (ADS)

    Ade, Peter A. R.; Arnold, Kam; Atlas, Matt; Baccigalupi, Carlo; Barron, Darcy; Boettger, David; Borrill, Julian; Chapman, Scott; Chinone, Yuji; Cukierman, Ari; Dobbs, Matt; Ducout, Anne; Dunner, Rolando; Elleflot, Tucker; Errard, Josquin; Fabbian, Giulio; Feeney, Stephen; Feng, Chang; Gilbert, Adam; Goeckner-Wald, Neil; Groh, John; Hall, Grantland; Halverson, Nils W.; Hasegawa, Masaya; Hattori, Kaori; Hazumi, Masashi; Hill, Charles; Holzapfel, William L.; Hori, Yasuto; Howe, Logan; Inoue, Yuki; Jaehnig, Gregory C.; Jaffe, Andrew H.; Jeong, Oliver; Katayama, Nobuhiko; Kaufman, Jonathan P.; Keating, Brian; Kermish, Zigmund; Keskitalo, Reijo; Kisner, Theodore; Kusaka, Akito; Le Jeune, Maude; Lee, Adrian T.; Leitch, Erik M.; Leon, David; Li, Yun; Linder, Eric; Lowry, Lindsay; Matsuda, Frederick; Matsumura, Tomotake; Miller, Nathan; Montgomery, Josh; Myers, Michael J.; Navaroli, Martin; Nishino, Haruki; Okamura, Takahiro; Paar, Hans; Peloton, Julien; Pogosian, Levon; Poletti, Davide; Puglisi, Giuseppe; Raum, Christopher; Rebeiz, Gabriel; Reichardt, Christian L.; Richards, Paul L.; Ross, Colin; Rotermund, Kaja M.; Schenck, David E.; Sherwin, Blake D.; Shimon, Meir; Shirley, Ian; Siritanasak, Praween; Smecher, Graeme; Stebor, Nathan; Steinbach, Bryan; Suzuki, Aritoki; Suzuki, Jun-ichi; Tajima, Osamu; Takakura, Satoru; Tikhomirov, Alexei; Tomaru, Takayuki; Whitehorn, Nathan; Wilson, Brandon; Yadav, Amit; Zahn, Alex; Zahn, Oliver; Polarbear Collaboration

    2015-12-01

    We constrain anisotropic cosmic birefringence using four-point correlations of even-parity E -mode and odd-parity B -mode polarization in the cosmic microwave background measurements made by the POLARization of the Background Radiation (POLARBEAR) experiment in its first season of observations. We find that the anisotropic cosmic birefringence signal from any parity-violating processes is consistent with zero. The Faraday rotation from anisotropic cosmic birefringence can be compared with the equivalent quantity generated by primordial magnetic fields if they existed. The POLARBEAR nondetection translates into a 95% confidence level (C.L.) upper limit of 93 nanogauss (nG) on the amplitude of an equivalent primordial magnetic field inclusive of systematic uncertainties. This four-point correlation constraint on Faraday rotation is about 15 times tighter than the upper limit of 1380 nG inferred from constraining the contribution of Faraday rotation to two-point correlations of B -modes measured by Planck in 2015. Metric perturbations sourced by primordial magnetic fields would also contribute to the B -mode power spectrum. Using the POLARBEAR measurements of the B -mode power spectrum (two-point correlation), we set a 95% C.L. upper limit of 3.9 nG on primordial magnetic fields assuming a flat prior on the field amplitude. This limit is comparable to what was found in the Planck 2015 two-point correlation analysis with both temperature and polarization. We perform a set of systematic error tests and find no evidence for contamination. This work marks the first time that anisotropic cosmic birefringence or primordial magnetic fields have been constrained from the ground at subdegree scales.

  16. Computational study to evaluate the birefringence of uniaxially oriented film of cellulose triacetate.

    PubMed

    Hayakawa, Daichi; Ueda, Kazuyoshi

    2015-01-30

    The intrinsic birefringence of a cellulose triacetate (CTA) film is evaluated using the polarizability of the monomer model of the CTA repeating unit, which is calculated using the density functional theory (DFT). Since the CTA monomer is known to have three rotational isomers, referred to as gg, gt, and tg, the intrinsic birefringence of these isomers is evaluated separately. The calculation indicates that the monomer CTA with gg and gt structures shows a negative intrinsic birefringence, whereas the monomer unit with a tg structure shows a positive intrinsic birefringence. By using these values, a model of the uniaxially elongated CTA film is constructed with a molecular dynamics simulation, and the orientation birefringence of the film model was evaluated. The result indicates that the film has negative orientation birefringence and that its value is in good agreement with experimental results. PMID:25498014

  17. Dual-beam-scan Doppler optical coherence angiography for birefringence-artifact-free vasculature imaging.

    PubMed

    Makita, Shuichi; Jaillon, Franck; Yamanari, Masahiro; Yasuno, Yoshiaki

    2012-01-30

    Dual-beam-scan Doppler optical coherence angiography (DB-OCA) enables high-speed, high-sensitivity blood flow imaging. However, birefringence of biological tissues is an obstacle to vasculature imaging. Here, the influence of polarization and birefringence on DB-OCA imaging was analyzed. A DB-OCA system without birefringence artifact has been developed by introducing a Faraday rotator. The performance was confirmed in vitro using chicken muscle and in vivo using the human eye. Birefringence artifacts due to birefringent tissues were suppressed. Micro-vasculatures in the lamina cribrosa and nerve fiber layer of human eyes were visualized in vivo. High-speed and high-sensitivity micro-vasculature imaging involving birefringent tissues is available with polarization multiplexing DB-OCA. PMID:22330505

  18. Neural network calibration of a snapshot birefringent Fourier transform spectrometer with periodic phase errors.

    PubMed

    Luo, David; Kudenov, Michael W

    2016-05-16

    Systematic phase errors in Fourier transform spectroscopy can severely degrade the calculated spectra. Compensation of these errors is typically accomplished using post-processing techniques, such as Fourier deconvolution, linear unmixing, or iterative solvers. This results in increased computational complexity when reconstructing and calibrating many parallel interference patterns. In this paper, we describe a new method of calibrating a Fourier transform spectrometer based on the use of artificial neural networks (ANNs). In this way, it is demonstrated that a simpler and more straightforward reconstruction process can be achieved at the cost of additional calibration equipment. To this end, we provide a theoretical model for general systematic phase errors in a polarization birefringent interferometer. This is followed by a discussion of our experimental setup and a demonstration of our technique, as applied to data with and without phase error. The technique's utility is then supported by comparison to alternative reconstruction techniques using fast Fourier transforms (FFTs) and linear unmixing. PMID:27409947

  19. Semiconductor optical amplifier direct modulation with double-stage birefringent fiber loop

    NASA Astrophysics Data System (ADS)

    Engel, Thomas; Rizou, Zoe V.; Zoiros, Kyriakos E.; Morel, Pascal

    2016-06-01

    The feasibility of cascading two birefringent fiber loops (BFLs) for directly modulating a conventional semiconductor optical amplifier (SOA) at a faster data rate than that being possible by its limited electrical bandwidth is demonstrated for the first time. The experimental results reveal the improvements in the quality characteristics of the encoded signal compared to those achieved with a single-stage BFL. The observed trends are complemented by numerical simulations, which allow to investigate the impact of the double-stage BFL detuning and specify how this critical parameter must be selected for enhanced performance. Provided that it is properly tailored, the proposed optical notch filtering scheme efficiently compensates for the pattern-dependent SOA response and enables this element to be employed as intensity modulator with improved performance at enhanced data speeds.

  20. Electrodynamics of a rotating body; Relativistic theory of circular and axial birefringence

    SciTech Connect

    Evans, M.W. . Dept. of Physics)

    1992-09-20

    In this paper, the theory of the electrodynamics of a rotating body is used to show that there exists: circular birefringence purely relativistic origin, composed of dispersive aether drag and residual, ensemble averaged, magnetization; non-relativistic circular birefringence due to the angular velocity of the body in the observer frame; non-relativistic axial birefringence in chiral media due to the angular velocity of the body; second order, relativistic equivalents.

  1. Influence of filler metal on birefringent optical properties of photonic crystal fiber with integrated electrodes

    NASA Astrophysics Data System (ADS)

    Reyes-Vera, Erick; Torres, Pedro

    2016-08-01

    We present a comprehensive study of the influence of the filler metal on the birefringent optical properties of a photonic crystal fiber containing two integrated electrodes. Bismuth and indium were used to examine the effects of the electrode composition on the temperature sensitivity of this special microstructured fiber. We found that the fiber microstructure significantly influences the metal-induced sensitivity of the wavelength dependent birefringence, making the behavior of the birefringence change strongly with the electrode material. By modeling the anisotropic changes induced by the metal expansion in the refractive index within the fiber we examine the essential features of the fiber birefringence.

  2. Birefringence properties of a polarization maintaining Panda fibre during Bragg grating regeneration

    NASA Astrophysics Data System (ADS)

    Polz, Leonhard; Jarsen, Andreas; Bartelt, Hartmut; Roths, Johannes

    2015-09-01

    Regeneration of fibre Bragg gratings under application of a high temperature annealing process in a high birefringent polarisation maintaining fibre of type Panda was investigated. During the annealing process, a distinct nonlinearity and hysteresis of the birefringence with temperature was observed. After the temperature process, the birefringence between slow and fast axis at room temperature was nearly doubled, which is in agreement with observations of other researchers. The hysteresis in birefringence might be explained by the crossing of the transition temperature of the stress applying parts and the relief of in-frozen mechanical and thermal stresses.

  3. Coupled-mode equation of polarization modes of twisted birefringent fibers in a unified coordinate.

    PubMed

    Fang, Zujie; Yang, Fei; Cai, Haiwen; Qu, Ronghui

    2013-01-20

    A coupled-mode equation (CME) of twisted birefringent fiber is presented in this paper, which uses the degenerate polarization modes of single-mode fibers as eigenmodes in a unified coordinate. The inconsistency between the coordinate and the rotating principal axis, existing in the previous CME, is solved by conversion to the lab coordinate. The CME gives self-consistent results for fibers with high birefringence or low birefringence and for single-mode fibers as well. Analyses and simulations show the CME gives characteristics of twisted birefringent fiber coincident with the property of polarization-maintaining fibers. PMID:23338204

  4. Shot-noise-limited measurement of sub-parts-per-trillion birefringence phase shift in a high-finesse cavity

    SciTech Connect

    Durand, Mathieu; Morville, Jerome; Romanini, Daniele

    2010-09-15

    We report on a promising approach to high-sensitivity anisotropy measurements using a high-finesse cavity locked by optical feedback to a diode laser. We provide a simple and effective way to decouple the weak anisotropy of interest from the inherent mirror's birefringence whose drift may be identified as the key limiting parameter in cavity-based techniques. We demonstrate a shot-noise-limited phase shift resolution previously inaccessible in an optical cavity, readily achieving the state-of-the-art level of 3x10{sup -13} rad.

  5. Thermally induced birefringence in Nd:YAG slab lasers

    SciTech Connect

    Ostermeyer, Martin; Mudge, Damien; Veitch, Peter J.; Munch, Jesper

    2006-07-20

    We study thermally induced birefringence in crystalline Nd:YAG zigzag slab lasers and the associated depolarization losses. The optimum crystallographic orientation of the zigzag slab within the Nd:YAG boule and photoelastic effects in crystalline Nd:YAG slabs are briefly discussed. The depolarization is evaluated using the temperature and stress distributions, calculated using a finite element model, for realistically pumped and cooled slabs of finite dimensions. Jones matrices are then used to calculate the depolarization of the zigzag laser mode. We compare the predictions with measurements of depolarization, and suggest useful criteria for the design of the gain media for such lasers.

  6. Birefringent Fourier transform imaging spectrometer with a rotating retroreflector.

    PubMed

    Bai, Caixun; Li, Jianxin; Shen, Yan; Zhou, Jianqiang

    2016-08-01

    A birefringent Fourier transform imaging spectrometer with a new lateral shearing interferometer is presented. The interferometer includes a Wollaston prism and a retroreflector. It splits an incident light beam into two shearing parallel parts to obtain interference fringe patterns of an imaging target, which is well established as an aid in reducing problems associated with optical alignment and manufacturing precision. Continuously rotating the retroreflector enables the spectrometer to acquire two-dimensional spectral images without spatial scanning. This technology, with a high work efficiency and low complexity, is inherently compact and robust. The effectiveness of the proposed method is demonstrated by the experimental results. PMID:27472640

  7. X-ray natural birefringence in reflection from graphene

    NASA Astrophysics Data System (ADS)

    Jansing, C.; Mertins, H.-Ch.; Gilbert, M.; Wahab, H.; Timmers, H.; Choi, S.-H.; Gaupp, A.; Krivenkov, M.; Varykhalov, A.; Rader, O.; Legut, D.; Oppeneer, P. M.

    2016-07-01

    The existence of natural birefringence in x-ray reflection on graphene is demonstrated at energies spanning the carbon 1 s absorption edge. This new x-ray effect has been discovered with precision measurements of the polarization-plane rotation and the polarization-ellipticity changes that occur upon reflection of linearly polarized synchrotron radiation on monolayer graphene. Extraordinarily large polarization-plane rotations of up to 30∘, accompanied by a change from linearly to circularly polarized radiation have been measured for graphene on copper. Graphene on single crystalline cobalt, grown on tungsten, exhibits rotation values of up to 17∘. Both graphene systems show resonantly enhanced effects at the π* and σ* energies. The results are referenced against those obtained for polycrystalline carbon and highly oriented pyrolytic graphite (HOPG), respectively. As expected, polycrystalline carbon shows negligible rotation, whereas a huge maximum rotation of 140∘ has been observed for HOPG that may be considered a graphene multilayer system. HOPG is found to exhibit such large rotation values over a broad energy range, even well beyond the π* resonance energy due to the contributions of numerous graphene layers. To explain the origin of the observed natural birefringence of graphene, the Stokes parameters as well as the x-ray natural linear dichroism in reflection have been determined. It is shown that the birefringence directly results from the optical anisotropy related to the orthogonal alignment of π* and σ* bonds in the graphene layer. Our polarization analysis reveals a strong bonding of graphene on Co with a reduced σ* excitation energy and a strong tilt of 50 % of the pz orbitals towards diagonal orientation. In contrast, graphene on Cu is weakly bound with an orthogonal orientation of the pz orbitals. Exhibiting such a large natural birefringence that can be controlled through substrate choice, and because of excellent heat conductivity

  8. Automated Detection of Ocular Alignment with Binocular Retinal Birefringence Scanning

    NASA Astrophysics Data System (ADS)

    Hunter, David G.; Shah, Ankoor S.; Sau, Soma; Nassif, Deborah; Guyton, David L.

    2003-06-01

    We previously developed a retinal birefringence scanning (RBS) device to detect eye fixation. The purpose of this study was to determine whether a new binocular RBS (BRBS) instrument can detect simultaneous fixation of both eyes. Control (nonmyopic and myopic) and strabismic subjects were studied by use of BRBS at a fixation distance of 45 cm. Binocularity (the percentage of measurements with bilateral fixation) was determined from the BRBS output. All nonstrabismic subjects with good quality signals had binocularity >75%. Binocularity averaged 5% in four subjects with strabismus (range of 0 -20%). BRBS may potentially be used to screen individuals for abnormal eye alignment.

  9. Compensation for thermally induced birefringence in polycrystalline ceramic active elements

    SciTech Connect

    Kagan, M A; Khazanov, E A

    2003-10-31

    Polycrystalline ceramics differ significantly from single crystals in that the crystallographic axes (and hence of the axes of thermally induced birefringence) are oriented randomly in each granule of the ceramic. The quaternion formalism is employed to calculate the depolarisation in the ceramics and the efficiency of its compensation. The obtained analytic expressions are in good agreement with the numerical relations. It is shown that the larger the ratio of the sample length to the granule size, the closer the properties of the ceramics to those of a single crystal with the [111] orientation (in particular, the uncompensated depolarisation is inversely proportional to this ratio). (active media)

  10. Variable bandwidth birefringent filter for tunable femtosecond lasers

    SciTech Connect

    Naganuma, K.; Lenz, G.; Ippen, E.P. )

    1992-10-01

    A design for a birefringent filter is described, which is suitable for tunable femtosecond lasers. Using a single plate, which has a steeply diving optic axis, two-octave tunability is attained with negligible deterioration of the stopband rejection. For a specific wavelength region, it means that the filter's bandwidth can be changed by a factor of four. Another characteristic of the design is that, for the same bandwidth, the proposed plate is five times thicker than a conventional plate in which the optic axis is parallel to the surface. Thus, etalon effects can be avoided. Tuning characteristics of color center lasers utilizing the new filter are also presented. 18 refs.

  11. High-speed polarization-sensitive optical coherence tomography for the investigation of tissue birefringence

    NASA Astrophysics Data System (ADS)

    Gulsen, Gultekin; Nalcioglu, Orhan

    2005-04-01

    Polarization-sensitive optical coherence tomography (PSOCT) is an optical imaging modality that is sensitive to the birefringence properties of tissues. Birefringence is related to various biological components and therefore, polarization can provide novel contrast mechanisms for imaging. In this work, we will describe the design of a high-speed polarization sensitive optical coherence tomography system. A broadband source centered at 1310nm with 35nm bandwidth was utilized as the light source. The output power of the source and the resolution of the system were around 20mW and ~20 micrometers, respectively. To achieve high-speed scan, a rapid scan optical delay line (RSOD) was utilized in the reference arm. It provided depth scanning up to 1000 A-scan/s and controlled the carrier frequency of the interference of fridge pattern. Two galvo-mounted mirrors were used for lateral scanning of the beam. The polarization state of the incident light was altered between horizontal and vertical states by using a fast polarization rotator. The combined light from the reference and the sample arms was split into two orthogonal polarization components by a polarizing beam splitter and coupled into two single-mode optical fibers that are connected to the photodiodes. The roundtrip Jones matrix of the sample arm was measured and used to calibrate the measurements of polarization properties of the sample. The elements of the Jones matrix of the sample were calculated by the using the output Jones vectors for the incident polarization states. The performance of the system was evaluated with standard samples such as a quarter-wave plate. The animal studies are currently undertaken to assess the performance of the system in-vivo.

  12. Temperature-independent zero-birefringence polymer for liquid crystal displays

    NASA Astrophysics Data System (ADS)

    Shikanai, M. D.; Tagaya, A.; Koike, Y.

    2016-03-01

    A polymer film that shows almost no orientational birefringence even when the polymer main chain is in an oriented state and almost no temperature dependence of orientational birefringence in the temperature range from around -40 to 85 °C was prepared. This temperature range is important because it is where in-car liquid crystal displays (LCDs) are generally used; therefore, it is desirable to have constant orientational birefringence over this range. We suggest a method to compensate for the intrinsic birefringence and temperature coefficient of intrinsic birefringence of individual polymers by copolymerizing monomers of homopolymers that display opposite signs of the two parameters described above. Analysis of four types of polymers, methyl methacrylate (MMA), 2,2,2-trifluoroethyl methacrylate, benzyl methacrylate (BzMA), and phenyl methacrylate (PhMA), reveal that they possess both positive and negative signs of their temperature coefficient of intrinsic birefringence. Using this approach, we prepare P(MMA/PhMA/BzMA) (39:23:38 wt. %), which exhibits almost no intrinsic birefringence and almost no temperature dependence of intrinsic birefringence. The retardation of this polymer film when drawn uniaxially scarcely changed (between 0.3 and 0.8 nm) between 12 and 70 °C, which is small enough not to cause image degradation in LCDs.

  13. Experimental studies of polarization properties of supercontinua generated in a birefringent photonic crystal fiber.

    PubMed

    Zhu, Zhaoming; Brown, Thomas

    2004-03-01

    Besides coherence degradations, supercontinuum spectra generated in birefringent photonic crystal fibers also suffer from polarization fluctuations because of noise in the input pump pulse. This paper describes an experimental study of polarization properties of supercontinuum spectra generated in a birefringent photonic crystal fiber, validating previous numerical simulations. PMID:19474887

  14. Birefringence-Directed Raman Selection Rules in 2D Black Phosphorus Crystals.

    PubMed

    Mao, Nannan; Wu, Juanxia; Han, Bowen; Lin, Jingjing; Tong, Lianming; Zhang, Jin

    2016-05-01

    The incident and scattered light engaged in the Raman scattering process of low symmetry crystals always suffer from the birefringence-induced depolarization. Therefore, for anisotropic crystals, the classical Raman selection rules should be corrected by taking the birefringence effect into consideration. The appearance of the 2D anisotropic materials provides an excellent platform to explore the birefringence-directed Raman selection rules, due to its controllable thickness at the nanoscale that greatly simplifies the situation comparing with bulk materials. Herein, a theoretical and experimental investigation on the birefringence-directed Raman selection rules in the anisotropic black phosphorus (BP) crystals is presented. The abnormal angle-dependent polarized Raman scattering of the Ag modes in thin BP crystal, which deviates from the normal Raman selection rules, is successfully interpreted by the theoretical model based on birefringence. It is further confirmed by the examination of different Raman modes using different laser lines and BP samples of different thicknesses. PMID:27030911

  15. On the birefringence of healthy and malaria-infected red blood cells

    NASA Astrophysics Data System (ADS)

    Dharmadhikari, Aditya K.; Basu, Himanish; Dharmadhikari, Jayashree A.; Sharma, Shobhona; Mathur, Deepak

    2013-12-01

    The birefringence of a red blood cell (RBC) is quantitatively monitored as it becomes infected by a malarial parasite. Large changes occur in the cell's refractive index at different stages of malarial infection. The observed rotation of an optically trapped, malaria-infected RBC is not a simple function of shape distortion: the malarial parasite is found to itself exercise a profound influence on the rotational dynamics by inducing stage-specific birefringence. Our measurements shed new light on the competition between shape- and form-birefringence in RBCs. We demonstrate the possibility of using birefringence to establish very early stages of infected parasites and of assessing various factors that contribute to birefringence in normal and infected cells. Our results have implications for the development and use of noninvasive techniques of quantifying changes in cell properties induced by malaria disease pathology.

  16. Spectral-Domain Measurements of Birefringence and Sensing Characteristics of a Side-Hole Microstructured Fiber

    PubMed Central

    Hlubina, Petr; Martynkien, Tadeusz; Olszewski, Jacek; Mergo, Pawel; Makara, Mariusz; Poturaj, Krzysztof; Urbańczyk, Waclaw

    2013-01-01

    We experimentally characterized a birefringent side-hole microstructured fiber in the visible wavelength region. The spectral dependence of the group and phase modal birefringence was measured using the methods of spectral interferometry. The phase modal birefringence of the investigated fiber increases with wavelength, but its positive sign is opposite to the sign of the group modal birefringence. We also measured the sensing characteristics of the fiber using a method of tandem spectral interferometry. Spectral interferograms corresponding to different values of a physical parameter were processed to retrieve the spectral phase functions and to determine the spectral dependence of polarimetric sensitivity to strain, temperature and hydrostatic pressure. A negative sign of the polarimetric sensitivity was deduced from the simulation results utilizing the known modal birefringence dispersion of the fiber. Our experimental results show that the investigated fiber has a very high polarimetric sensitivity to hydrostatic pressure, reaching −200 rad × MPa−1× m−1 at 750 nm. PMID:23989824

  17. Development and characterization of orthotropic-birefringent materials

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Koller, G. M.; Niiro, T.

    1984-01-01

    Materials were selected and fabrication procedures developed for orthotropic birefringent materials. An epoxy resin (Maraset 658/558 system) was selected as the matrix material. Fibers obtained from style 3733 glass cloth and type 1062 glass roving were used as reinforcement. Two different fabrication procedures were used. In the first one, layers of unidirectional fibers removed from the glass cloth were stacked, impregnated with resin, bagged and cured in the autoclave at an elevated temperature. In the second procedure, the glass roving was drywound over metal frames, impregnated with resin and cured at room temperature under pressure and vacuum in an autoclave. Unidirectional, angle-ply and quasi-isotropic laminates of two thicknesses and with embedded flaws were fabricated. The matrix and the unidirectional glass/epoxy material were fully characterized. The density, fiber volume ratio, mechanical, and optical properties were determined. The fiber volume ratio was over 0.50. Birefringent properties were in good agreement with predictions based on a stress proportioning concept and also, with one exception, with properties predicted by a finite element analysis. Previously announced in STAR as N81-26183

  18. Magnetic birefringence studies of dilute purple membrane suspensions.

    PubMed Central

    Lewis, B A; Rosenblatt, C; Griffin, R G; Courtemanche, J; Herzfeld, J

    1985-01-01

    We have observed the magnetically induced orientation of purple membrane suspensions by measuring the birefringence as a function of concentration and temperature at fields up to 10.5 Tesla (T). At these fields, the orientation approaches saturation even in dilute solutions; therefore, the birefringence data, together with an estimate of the membrane size distribution obtained from electron microscopy, permits one to determine the diamagnetic susceptibility anisotropy. We find delta chi mole = 1.2 +/- 0.3 X 10(-3) erg G-2mol-1 of bacteriorhodopsin. If delta chi were due only to the oriented peptide bonds of the transmembrane alpha helices, this experimental value would indicate that delta K, the anisotropy per mole of peptide bonds, is considerably larger than previously suggested. On the other hand, the large value for delta chi mole of bacteriorhodopsin can also be explained by a net orientation of the aromatic amino acid side chains of bacteriorhodopsin with their planes perpendicular to the membrane surface. In addition, the present data analysis demonstrates the critical dependence of the calculated delta chi value on the values for the membrane size distribution. PMID:3978196

  19. Electrically induced birefringence in nanoparticle dispersions for electrorheological applications

    NASA Astrophysics Data System (ADS)

    Pochylski, Mikolaj; Calandra, Pietro; Aliotta, Francesco; Ponterio, Rosina C.

    2014-11-01

    Recently, the observation of an anomalously large electrorheological effect in the dispersion of nanosized particles of titania in octanoid acid has been reported. Such an enhanced effect was not observed in the similar dispersion of micrometric particles or in more conventional suspensions of silica in silicon oil. It was suggested that this effect could be promoted by the formation of a thin layer of solvent molecules on the surface of the titania particles. We propose the measurement of electrically induced optical birefringence as a suitable independent method for testing this working hypothesis. In this paper, we report the results from the investigations of the dilute dispersions of 32 nm TiO2 particles in two insulating fluids: silicone oil and octanoic acid. A comparison of the experimental birefringence data with the theoretical predictions suggests that TiO2 nanoparticles behave like permanent electric dipoles, although induced dipoles are expected in the case of the titania material. The source of such behaviour has been individuated at the particle/solvent interface and the different possibilities of the permanent dipole origin are discussed. The lower value of the dipole moment observed in octanoic acid dispersion is explained in terms of a specific particle/solvent interaction leading to the formation of a solvent coating around the particle. The results highlight that electro-optical properties are related to electrorheological performance and that both methods can be considered as supportive for testing electrically driven phenomena in complex fluids.

  20. Development of orthotropic birefringent materials for photoelastic stress analysis

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Niiro, T.; Koller, G. M.

    1981-01-01

    Materials were selected and fabrication procedures developed for orthotropic birefringent materials. An epoxy resin (Maraset 658/558 system) was selected as the matrix material. Fibers obtained from style 3733 glass cloth and type 1062 glass roving were used as reinforcement. Two different fabrication procedures were used. In the first one, layers of unidirectional fibers removed from the glass cloth were stacked, impregnated with resin, bagged and cured in the autoclave at an elevated temperature. In the second procedure, the glass roving was drywound over metal frames, impregnated with resin and cured at room temperature under pressure and vacuum in an autoclave. Unidirectional, angle-ply and quasi-isotropic laminates of two thicknesses and with embedded flaws were fabricated. The matrix and the unidirectional glass/epoxy material were fully characterized. The density, fiber volume ratio, mechanical, and optical properties were determined. The fiber volume ratio was over 0.50. Birefringent properties were in good agreement with predictions based on a stress proportioning concept and also, with one exception, with properties predicted by a finite element analysis.

  1. Anisotropic Transverse Stress in Calcite and Sapphire Measured Using Birefringence

    NASA Astrophysics Data System (ADS)

    Tear, Gareth R.; Chapman, David J.; Eakins, Daniel E.; Proud, William G.

    2015-06-01

    Many significant geological minerals have anisotropic crystal structures leading to material properties that are anisotropic, including compressive elastic behaviour. A non-invasive approach to investigate the directional dependence of transverse stress in these materials during shock compression would supplement current understanding. As many geological minerals are transparent and hence optically anisotropic, measuring the change in birefringence induced by transverse stress in the material offers the possibility of a fast, non-invasive approach to probe transverse behaviour. Shock compression experiments have been performed on a-cut calcite and a-cut sapphire for strain rates of order 105 s-1 and up to longitudinal stresses of 2 GPa for calcite and 12 GPa for sapphire. We present measured changes in birefringence for these materials under shock compression, comparing with current and past literature as well as an in house optical model. The authors would like to thank Mr Steve Johnson and Mr David Pittman for technical support. The Institute of Shock Physics acknowledges the continued support of AWE and Imperial College London.

  2. Bright and black paired soliton states in birefringent optical fibers

    NASA Astrophysics Data System (ADS)

    Chen, Yijiang

    1996-08-01

    It is shown that a bright stationary light pulse evolving along the slow axis of a birefringent fiber in the anomalous dispersion regime can be locked to move in the same group velocity together with a black-soliton pulse trapped along the fast axis in the normal dispersion regime despite each individual pulse's, in the absence of the other, propagating at different group velocities. Such a stationary copropagation of the bright and the black soliton pulses with the same group velocity in coherent trapping can sustain up to a finite distance owing to polarization modulation instability of the black-pulse background that breaks the stationary evolution into radiation. In incoherent trapping the bright-black paired soliton state also disintegrates with propagation distance, and the disintegration is accompanied by emission of bright and gray solitons that has potential for ultrafast optical switching. On the other hand, it is found that the two black-soliton pulses polarized along the principal axes of the birefringent fiber in the normal dispersion regime can evolve stably, in contrast to the paired spatial black solitons of different frequencies and parametric black solitons that break up with propagation distance owing to modulational instability of the cw backgrounds.

  3. Group-Velocity-Matched Three Wave Mixing in Birefringent Crystals

    SciTech Connect

    SMITH,ARLEE V.

    2000-12-12

    We show that the combination of pulse-front slant, k-vector tilt, and crystal birefringence often permits exact matching of both phase and group velocities in three wave mixing in birefringent crystals. This makes possible more efficient mixing of short light pulses, and it permits efficient mixing of chirped or broad bandwidth light. We analyze this process and present examples. Differences in the group velocities of the three interacting waves in a nonlinear crystal often limits the effective interaction length. For example, in mixing very short pulses, temporal walk off can stretch the pulses in time unless the crystal is very short. Efficient mixing with such short crystals requires high irradiances, but the irradiances are limited by higher order nonlinear effects such as intensity-dependent refractive index and two-photon absorption. Improved matching of the group velocities can alleviate this problem, allowing longer crystal and lower irradiances. Similarly, for high energy pulses, practical limits on crystal apertures mandate temporally stretching the pulses to reduce irradiances. For the resulting chirped pulses, temporal walk off restricts the chirp range unless the group velocities are well matched. In addition to perfectly matching the group velocities of all three waves, it is sometimes useful to match two velocities, such as the signal and idler in parametric amplification, permitting broadband parametric amplification, or to arrange the velocities of two inputs to bracket the generated sum frequency pulse, giving pulse compression under suitable circumstances.

  4. Including birefringence into time evolution of CMB: current and future constraints

    SciTech Connect

    Gubitosi, G.; Pagano, L.; Martinelli, M. E-mail: martinelli@thphys.uni-heidelberg.de

    2014-12-01

    We introduce birefringence effects within the propagation history of CMB, considering the two cases of a constant effect and of an effect that increases linearly in time, as the rotation of polarization induced by birefringence accumulates during photon propagation. Both cases result into a mixing of E and B modes before lensing effects take place, thus leading to the fact that lensing is acting on spectra that are already mixed because of birefringence. Moreover, if the polarization rotation angle increases during propagation, birefringence affects more the large scales that the small scales. We put constraints on the two cases using data from WMAP 9yr and BICEP 2013 and compare these results with the constraints obtained when the usual procedure of rotating the final power spectra is adopted, finding that this dataset combination is unable to distinguish between effects, but it nevertheless hints for a non vanishing value of the polarization rotation angle. We also forecast the sensitivity that will be obtained using data from Planck and PolarBear, highlighting how this combination is capable to rule out a vanishing birefringence angle, but still unable to distinguish the different scenarios. Nevertheless, we find that the combination of Planck and PolarBear is sensitive enough to highlight the existence of degeneracies between birefringence rotation and gravitational lensing of CMB photons, possibly leading to false detection of non standard lensing effects if birefringence is neglected.

  5. Single-mode fibre optic Bragg grating sensing on the base of birefringence in surface-mounting and embedding applications

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ryul; Tsuda, Hiroshi; Koo, Bon-Yong

    2007-02-01

    Birefringence effects in the two typical installation techniques of fibre Bragg grating(FBG) sensor are investigated: surface-mounting and embedding configurations. When the FBG is bonded on a host material, the sensitivity loss in ultrasonic measurement caused by glue-induced low-birefringence is first reported. Next, the transverse stress-induced high birefringence when the FBG is embedded into a fabric composite laminate is measured as 3.6×10 -4. Such induced-birefringence effects are experimentally analysed in mechanical applications. Simple and effective solutions with respect to the respective installation configurations for removing the birefringence effect are proposed and the obtained zero-birefringence cases are compared with the birefringent cases.

  6. Two-dimensional electronic spectroscopy with birefringent wedges

    NASA Astrophysics Data System (ADS)

    Réhault, Julien; Maiuri, Margherita; Oriana, Aurelio; Cerullo, Giulio

    2014-12-01

    We present a simple experimental setup for performing two-dimensional (2D) electronic spectroscopy in the partially collinear pump-probe geometry. The setup uses a sequence of birefringent wedges to create and delay a pair of phase-locked, collinear pump pulses, with extremely high phase stability and reproducibility. Continuous delay scanning is possible without any active stabilization or position tracking, and allows to record rapidly and easily 2D spectra. The setup works over a broad spectral range from the ultraviolet to the near-IR, it is compatible with few-optical-cycle pulses and can be easily reconfigured to two-colour operation. A simple method for scattering suppression is also introduced. As a proof of principle, we present degenerate and two-color 2D spectra of the light-harvesting complex 1 of purple bacteria.

  7. Birefringence effects of short probe pulses of electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Parshkov, Oleg M.; Kochetkova, Anastasia E.; Budyak, Victoria V.

    2016-04-01

    The numerical simulation results of radiations evolution in the presence of electromagnetically induced transparency for J=0-->J=1-->J=2 scheme of degenerate quantum transitions are presented. The pulse regime of wave interaction with Doppler broadening spectral lines was investigated. It was indicated that when the control field is linear polarized, the input circular polarized probe pulse breaks up in the medium into pulses with mutually perpendicular linear polarizations. Polarization direction of one of these pulses coincides with the polarization direction of control fields. The distance, which probe pulse passes in the medium to its full separation, decreases, when input probe pulse duration or control field intensity decreases. The input probe pulse intensity variation almost does not influence separation distance and speed of the linear polarized probe pulses in the medium. The effects, described above, may be interpreted as the birefringence effects of electromagnetically induced transparency in the case of short probe pulse.

  8. Birefringent breakup of Dirac fermions on a square optical lattice

    SciTech Connect

    Kennett, Malcolm P.; Komeilizadeh, Nazanin; Kaveh, Kamran; Smith, Peter M.

    2011-05-15

    We introduce a lattice model for fermions in a spatially periodic magnetic field that also has spatially periodic hopping amplitudes. We discuss how this model might be realized with cold atoms in an artificial magnetic field on a square optical lattice. When there is an average flux of half a flux quantum per plaquette, the spectrum of low-energy excitations can be described by massless Dirac fermions in which the usually doubly degenerate Dirac cones split into cones with different ''speeds of light.'' These gapless birefringent Dirac fermions arise because of broken chiral symmetry in the kinetic energy term of the effective low-energy Hamiltonian. We characterize the effects of various perturbations to the low-energy spectrum, including staggered potentials, interactions, and domain-wall topological defects.

  9. Birefringence and anisotropic optical absorption in porous silicon

    SciTech Connect

    Efimova, A. I. Krutkova, E. Yu.; Golovan', L. A.; Fomenko, M. A.; Kashkarov, P. K.; Timoshenko, V. Yu.

    2007-10-15

    The refractive indices and the coefficients of optical absorption by free charge carriers and local vibrations in porous silicon (por-Si) films, comprising nanometer-sized silicon residues (nanocrystals) separated by nanometer-sized pores (nanopores) formed in the course of electrochemical etching of the initial single crystal silicon, have been studied by polarization-resolved IR absorption spectroscopy techniques. It is shown that the birefringence observed in por-Si is related to the anisotropic shapes of nanocrystals and nanopores, while the anisotropy (dichroism) of absorption by the local vibrational modes is determined predominantly by the microrelief of the surface of nanocrystals. It is demonstrated that silicon-hydrogen surface bonds in nanocrystals can be restored by means of selective hydrogen thermodesorption with the formation of a considerable number of H-terminated surface Si-Si dimers.

  10. Dynamics of photoinduced dichroism and birefringence in optically thick azopolymers

    SciTech Connect

    Ponomarev, Yu V; Ivanov, Yu V; Rumyantsev, Yu A; Gromchenko, A A

    2009-01-31

    Dynamics of photoinduced dichroism and birefringence have been studied experimentally and theoretically (with the help of the Dumont model) by using some comb-shaped azopolymers. It is shown that the dynamics of trans-isomer concentration and their angular distribution anisotropy can be restored from the experimentally found dichroism dynamics, with the concentration and anisotropy being averaged over the thickness for optically thick samples. At the initial stage of photoinduced anisotropy when the active role of the polymer matrix can be neglected, the experimental time dependence of dichroism is shown to comply well with the Dumont model even if the orientation memory is neglected, provided that only a part of trans-isomers participates in trans-isomerisation. (nonlinear optical phenomena)

  11. Birefringence, CMB polarization, and magnetized B-mode

    SciTech Connect

    Giovannini, Massimo; Kunze, Kerstin E.

    2009-04-15

    Even in the absence of a sizable tensor contribution, a B-mode polarization can be generated because of the competition between a pseudoscalar background and predecoupling magnetic fields. By investigating the dispersion relations of a magnetoactive plasma supplemented by a pseudoscalar interaction, the total B-mode polarization is shown to depend not only upon the plasma and Larmor frequencies but also on the pseudoscalar rotation rate. If the (angular) frequency channels of a given experiment are larger than the pseudoscalar rotation rate, the only possible source of (frequency-dependent) B-mode autocorrelations must be attributed to Faraday rotation. In the opposite case the pseudoscalar contribution dominates and the total rate becomes, in practice, frequency independent. The B-mode cross correlations can be used, under certain conditions, to break the degeneracy by disentangling the two birefringent contributions.

  12. Two-dimensional electronic spectroscopy with birefringent wedges

    SciTech Connect

    Réhault, Julien; Maiuri, Margherita; Oriana, Aurelio; Cerullo, Giulio

    2014-12-15

    We present a simple experimental setup for performing two-dimensional (2D) electronic spectroscopy in the partially collinear pump-probe geometry. The setup uses a sequence of birefringent wedges to create and delay a pair of phase-locked, collinear pump pulses, with extremely high phase stability and reproducibility. Continuous delay scanning is possible without any active stabilization or position tracking, and allows to record rapidly and easily 2D spectra. The setup works over a broad spectral range from the ultraviolet to the near-IR, it is compatible with few-optical-cycle pulses and can be easily reconfigured to two-colour operation. A simple method for scattering suppression is also introduced. As a proof of principle, we present degenerate and two-color 2D spectra of the light-harvesting complex 1 of purple bacteria.

  13. Refractive index and birefringence of 2H silicon carbide

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1972-01-01

    The refractive indices of 2H SiC were measured over the wavelength range 435.8 to 650.9 nm by the method of minimum deviation. At the wavelength lambda = 546.1 nm, the ordinary index n sub 0 was 2.6480 and the extraordinary index n sub e was 2.7237. The estimated error (standard deviation) in the measured values is 0.0006 for n sub 0 and 0.0009 for n sub e. The experimental data were curve fitted to the Cauchy equation for the index of refraction as a function of wavelength. The birefringence of 2H SiC was found to vary from 0.0719 at lambda = 650.9 nm to 0.0846 at lambda = 435.8 nm.

  14. Two-dimensional electronic spectroscopy with birefringent wedges.

    PubMed

    Réhault, Julien; Maiuri, Margherita; Oriana, Aurelio; Cerullo, Giulio

    2014-12-01

    We present a simple experimental setup for performing two-dimensional (2D) electronic spectroscopy in the partially collinear pump-probe geometry. The setup uses a sequence of birefringent wedges to create and delay a pair of phase-locked, collinear pump pulses, with extremely high phase stability and reproducibility. Continuous delay scanning is possible without any active stabilization or position tracking, and allows to record rapidly and easily 2D spectra. The setup works over a broad spectral range from the ultraviolet to the near-IR, it is compatible with few-optical-cycle pulses and can be easily reconfigured to two-colour operation. A simple method for scattering suppression is also introduced. As a proof of principle, we present degenerate and two-color 2D spectra of the light-harvesting complex 1 of purple bacteria. PMID:25554272

  15. Improvement in birefringent filters. IV - The alternate partial polarizer filter

    NASA Technical Reports Server (NTRS)

    Title, A. M.

    1976-01-01

    The design and performance of a birefringent filter with alternate partial polarizers are analyzed. The properties of several filter configurations with imperfect intermediate polarizers are examined. It is shown that such filters have significant advantages in transmission and profile shape over both the standard Lyot and the contrast element Lyot filters. These theoretical advantages are demonstrated by the measured properties of an actual filter using the alternate partial polarizer (APP) design. This filter is a four-module eight-crystal APP device which has been built using Polaroid HN-38 for the perfect polarizers and two laminated sheets of HN-55 for the partial polarizers. The measured characteristics of the filter are found to be in good agreement with theory.

  16. Integrated polarizers based on tapered highly birefringent photonic crystal fibers.

    PubMed

    Romagnoli, Priscila; Biazoli, Claudecir R; Franco, Marcos A R; Cordeiro, Cristiano M B; de Matos, Christiano J S

    2014-07-28

    This paper proposes and demonstrates the creation of sections with a high polarization dependent loss (PDL) in a commercial highly birefringent (polarization maintaining) photonic crystal fiber (PCF), via tapering with pressure applied to the holes. The tapers had a 1-cm-long uniform section with a 66% scale reduction, in which the original microstructure aspect ratio was kept by the pressure application. The resulting waveguides show polarizing action across the entire tested wavelength range, 1510-1600 nm, with a peak PDL of 35.3 dB/cm (c.f. ~1 dB/cm for a typical commercial polarizing fiber). The resulting structure, as well as its production, is extremely simple, and enable a small section with a high PDL to be obtained in a polarization maintaining PCF, meaning that the polarization axes in the polarizing and polarization maintaining sections are automatically aligned. PMID:25089397

  17. The Double Jones Birefringence in Magneto-electric Medium

    PubMed Central

    Mahmood, Waqas; Zhao, Qing

    2015-01-01

    In this paper, the Maxwell’s equations for a tensorial magneto-electric (ME) medium are solved, which is an extension to the work on the uniaxial anisotropic nonmagnetic medium. The coefficients of the dielectric permittivity, magnetic permeability, and of the magneto-electric effect are considered as tensors. The polarization is shown lying in the plane of two perpendicular independent vectors, and the relationship for the transverse polarization is given. The propagation of an electromagnetic wave through a ME medium gives rise to double Jones birefringence. Besides, the condition for an independent phenomenon of D’yakonov surface wave in a magneto-isotropic but with magneto-electric medium is given, which is measurable experimentally when the incident angle is . Lastly, it is shown that the parameter for the magneto-electric effect plays a role in the damping of the wave. PMID:26354609

  18. Quantification of fatigue state in CFRP using ultrasonic birefringence

    NASA Astrophysics Data System (ADS)

    Fey, Peter; Kreutzbruck, Marc

    2016-02-01

    Fiber reinforced plastics are widely used in high performance application areas such as aerospace, automotive and wind energy. They are preferred over classic materials such as metals because of their superior weight to stiffness ratio. When subjected to cyclic or static loading, micro-cracks develop and hence their stiffness degrades. The rate of stiffness degradation depends on the angle between the fibers and the applied load. Because commonly used fiber reinforced composites consist of multiple layers with different fiber directions to cope with different loads applied to the material, the stiffness degradation has to be analyzed for each fiber direction. One method to analyze the stiffness degradation in fiber reinforced materials is ultrasonic birefringence. A birefringent effect as it is known for light in optics is also observed for ultrasonic shear waves in fiber reinforced composites because of their elastic anisotropy. The role of the polarization dependent refractive index is taken by the propagation velocity of shear waves. If polarized parallel to the fiber direction they have a higher velocity than polarized perpendicularly to the fiber direction. The velocity depends on shear stiffness of the material. A model to predict the behavior of shear waves in multi-ply layups has been presented previously by Rheinfurth, Fey, Allinger and Busse[1]. That model was used to manually match measured and simulated phase and amplitude curves for waves that traversed the material under different angles between polarization direction of the emitting transducer and fiber direction in the first ply. Here another mode of interpreting the simulated results is used: amplitude and phase for each transducer orientation angle are combined to a complex number. Displaying them in the complex plane for one half rotation of the transducer yields an ellipse. Semi axis lengths and orientation can be obtained by Fourier transform and are used to compare the simulation to measured

  19. Birefringence and DNA Condensation of Liquid Crystalline Chromosomes ▿

    PubMed Central

    Chow, Man H.; Yan, Kosmo T. H.; Bennett, Michael J.; Wong, Joseph T. Y.

    2010-01-01

    DNA can self-assemble in vitro into several liquid crystalline phases at high concentrations. The largest known genomes are encoded by the cholesteric liquid crystalline chromosomes (LCCs) of the dinoflagellates, a diverse group of protists related to the malarial parasites. Very little is known about how the liquid crystalline packaging strategy is employed to organize these genomes, the largest among living eukaryotes—up to 80 times the size of the human genome. Comparative measurements using a semiautomatic polarizing microscope demonstrated that there is a large variation in the birefringence, an optical property of anisotropic materials, of the chromosomes from different dinoflagellate species, despite their apparently similar ultrastructural patterns of bands and arches. There is a large variation in the chromosomal arrangements in the nuclei and individual karyotypes. Our data suggest that both macroscopic and ultrastructural arrangements affect the apparent birefringence of the liquid crystalline chromosomes. Positive correlations are demonstrated for the first time between the level of absolute retardance and both the DNA content and the observed helical pitch measured from transmission electron microscopy (TEM) photomicrographs. Experiments that induced disassembly of the chromosomes revealed multiple orders of organization in the dinoflagellate chromosomes. With the low protein-to-DNA ratio, we propose that a highly regulated use of entropy-driven force must be involved in the assembly of these LCCs. Knowledge of the mechanism of packaging and arranging these largest known DNAs into different shapes and different formats in the nuclei would be of great value in the use of DNA as nanostructural material. PMID:20400466

  20. Birefringence in anisotropic optical fibres studied by polarised light Brillouin reflectometry

    SciTech Connect

    Smirnov, A S; Burdin, V V; Konstantinov, Yu A; Petukhov, A S; Drozdov, I R; Kuz'minykh, Ya S; Besprozvannykh, V G

    2015-01-31

    Modal birefringence (the difference between the effective refractive indices of orthogonal polarisation modes) is one of the key parameters of anisotropic single-mode fibres, characterising their ability to preserve a linearly polarised state of input light. This parameter is commonly measured using short pieces of fibre, but such procedures are destructive and allow the birefringence to be determined only at the ends of long fibres. In this study, polarised light Brillouin reflectometry is used to assess birefringence uniformity throughout the length of an anisotropic fibre. (optical fibres)

  1. Development of birefringence imaging analysis method for observing cubic crystals in various phase transitions.

    PubMed

    Manaka, Hirotaka; Yagi, Genta; Miura, Yoko

    2016-07-01

    Optical birefringence imaging systems demonstrate a high potential for comprehensively investigating various phase transitions. To completely demonstrate such abilities, the temperature dependence of birefringence (Δn) was measured in Δn ≃ 0 materials (i.e., cubic crystals with imperfect crystallization) via a background subtraction method. As a result, highly accurate birefringence imaging at 384 × 288 pixels was obtained using phase transition processes as well as varying temperatures visually characterized by the spatial distribution of not only the retardance level but also the optical fast-axis azimuth. PMID:27475562

  2. Low-level birefringence measurement by cyclic-path polarization interferometer.

    PubMed

    Chakraborty, Sonali; Bhattacharya, K

    2016-07-20

    A modified cyclic-path interferometer is employed for complete measurement of spatially varying birefringence. An expanded and collimated laser beam intercepted by a birefringent specimen is incident on a polarization-masked cube beam splitter, resulting in two mutually orthogonal polarization components propagating along clockwise and counterclockwise directions in the interferometer. These two wavefronts are made to interfere for four specific orientations of an analyzer. Suitable combinations of the interferograms result in determination of the direction of birefringence and its magnitude. Experimental results are presented. PMID:27463918

  3. Dielectric relaxation and birefringence study of 7.O5O.7 dimeric liquid crystal compound

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Debanjan; Paul-Choudhury, Sandip; Alapati, Parameswara Rao; Bhattacharjee, Ayon

    2016-05-01

    Measurement of dielectric relaxation and birefringence phenomenon of dimeric liquid crystal compound with the dependence of temperature was reported in this paper. Homogeneous (HG) and homeotropic (HT) alignment of the cell are introduced to investigate the dielectric relaxation, activation energy and birefringence. Cole-Cole plots analyzed the dielectric relaxation of the dimeric compound. The observed Cole-Cole plots were semi-circular, and the relaxation mechanism obeys the non-Debye type of relaxation behaviour. Slater's perturbation equations have been used to analysis the activation energy of the compound. The birefringence of the compound has positively anisotropy and thin prism mechanism was used to study the anisotropy of the compound.

  4. Birefringence of solid-state laser media: broadband tuning discontinuities and application to laser line narrowing

    SciTech Connect

    Krasinski, J.S.; Band, Y.B.; Chin, T.; Heller, D.F.; Morris, R.C.; Papanestor, P.

    1989-04-15

    Spectral consequences that result from using birefringent media with broadband gain inside of laser cavities containing polarizing elements are described. We show that the laser intensity is modulated as a function of the output frequency unless the cavity elements are carefully aligned so that their polarization axis coincides with a principal optical axis of the gain medium. Analysis of the tuning characteristics of a birefringent polarization-dependent gain medium is exploited to provide a simple method for line narrowing the laser output. By introduction of an intracavity birefringent compensator the narrow-band output can be continuously tuned. Experimental results for alexandrite lasers are presented.

  5. Development of birefringence imaging analysis method for observing cubic crystals in various phase transitions

    NASA Astrophysics Data System (ADS)

    Manaka, Hirotaka; Yagi, Genta; Miura, Yoko

    2016-07-01

    Optical birefringence imaging systems demonstrate a high potential for comprehensively investigating various phase transitions. To completely demonstrate such abilities, the temperature dependence of birefringence (Δn) was measured in Δn ≃ 0 materials (i.e., cubic crystals with imperfect crystallization) via a background subtraction method. As a result, highly accurate birefringence imaging at 384 × 288 pixels was obtained using phase transition processes as well as varying temperatures visually characterized by the spatial distribution of not only the retardance level but also the optical fast-axis azimuth.

  6. Determination of the Dispersion of the Principal Refractive Indices for Birefringent Polypropylene Films

    NASA Astrophysics Data System (ADS)

    Bezruchenko, V. S.; Murauski, An. A.; Muravsky, Al. A.

    2014-07-01

    We present a novel method for determining the dispersion of the refractive indices of birefringent films, based on treatment of transmission spectra, in which we observe interference of light. The dispersion curves n x (λ) and n y (λ) were determined by treatment of transmission spectra obtained for normal incidence of radiation on a P2-25 birefringent fi lm, and n z (λ) was determined for oblique incidence of radiation. From the results of determination of the dispersions of the principal refractive indices of a birefringent P2-25 polypropylene film (Mogilevkhimvolokno OAO, Belarus), we established that the sample is a negative biaxial retarder with N z = 2.9.

  7. Birefringence changes associated with isometric contraction and rapid shortening steps in frog skeletal muscle fibres.

    PubMed Central

    Irving, M

    1993-01-01

    1. Muscle birefringence, the difference between the refractive indices of light polarized parallel and perpendicular to the muscle fibre axis, was measured at 3 degrees C in intact single fibres isolated from frog muscle. Resting birefringence was 2.20 +/- 0.02 x 10(-3) (mean +/- S.E.M., n = 44) at sarcomere length 2.4-2.7 microns and 2.35 +/- 0.03 x 10(-3) (n = 19) at 3.5-3.8 microns. 2. Birefringence decreased during isometric twitch or tetanic contractions. The peak change in a twitch at sarcomere length 2.6 microns, determined by two independent methods, was 0.150 +/- 0.017 x 10(-3) (mean +/- S.E.M., n = 6). The corresponding value after 0.4 s of tetanic stimulation was 0.167 +/- 0.012 x 10(-3) (n = 6). 3. The birefringence change had a shorter latency than tension and reached its half-maximum value earlier than tension. The difference in time to half-maximum in tetani was 11.5 +/- 1.3 ms (mean +/- S.E.M., n = 6) at 3 degrees C. After stimulation birefringence recovered to its pre-stimulus baseline more slowly than tension. 4. The birefringence decrease after 0.4 s of tetanic stimulation was linearly related to the expected degree of overlap between actin and myosin filaments in the sarcomere length range 2.6-3.6 microns. The amplitude of the birefringence decrease at full filament overlap (sarcomere length 2.2 microns) was estimated to be 0.235 +/- 0.015 x 10(-3). 5. Birefringence changes associated with shortening steps of 0.9% fibre length at sarcomere length 2.6 microns exhibited four phases corresponding to those of the tension transient. There was no consistent birefringence change during the length step itself. During the rapid tension recovery birefringence increased by 0.014 +/- 0.001 x 10(-3) (n = 3), measured from the end of the length step to 2 ms later. Birefringence continued to increase as tension recovery slowed, reaching a peak about 10 ms after the step, then recovered with a rate similar to that of the final tension recovery. 6. These

  8. Temperature dependences of phase and group birefringence in spun fibres

    SciTech Connect

    Morshnev, S K; Gubin, V P; Przhiyalkovsky, Y V; Starostin, N I

    2013-12-31

    We consider the application of the spectral method for measuring the beat length of birefringence in spun fibre. We have found that the beat length measured in spun fibres is the geometric mean of phase and group birefringence beat lengths. Temperature measurements of beat lengths and shifts of the entire spectrum as a whole make it possible to separate types of birefringence and to determine their dispersion. We have performed an experiment on a spun fibre and a linear polarisation maintaining fibre, drawn from the same preform. The experimental results confirm the theory. (fiber and integrated optics)

  9. Multimode Brillouin spectrum in a long tapered birefringent photonic crystal fiber.

    PubMed

    Tchahame, Joël Cabrel; Beugnot, Jean-Charles; Kudlinski, Alexandre; Sylvestre, Thibaut

    2015-09-15

    We investigate the stimulated Brillouin scattering (SBS) in a long tapered birefringent solid-core photonic crystal fiber (PCF) and compare our results with a similar but untapered PCF. It is shown that the taper generates a broadband and multipeaked Brillouin spectrum, while significantly increasing the threshold power. Furthermore, we observe that the strong fiber birefringence gives rise to a frequency shift of the Brillouin spectrum which increases along the fiber. Numerical simulations are also presented to account for the taper effect and the birefringence. Our findings open a new means to control or inhibit the SBS by tapering photonic crystal fibers. PMID:26371916

  10. Dynamic compensation of thermal lensing and birefringence in a high-brightness Nd:Cr:GSGG oscillator

    NASA Astrophysics Data System (ADS)

    Moshe, Inon; Jackel, Steven M.; Lallouz, Raphael; Tzuk, I.

    1997-09-01

    In this work, five fundamental concepts were combined to a low development of high efficiency, low divergence, narrow bandwidth, flashlamp pumped oscillators capable of operation over a broad operating range. These concepts were: flashlamp pumped Nd:Cr:GSGG to achieve high efficiency, a 'Reentrant Cavity' to eliminate birefringence losses, a variable radius back mirror in a hemispherical cavity to achieve maximum Gaussian beam fill factor, a very high damage threshold, spectrum narrowing output coupler fabricated using a stack of uncoated etalons to form a resonant reflector, a cylindrical zoom lens to completely eliminate astigmatism. The results were successful, and yielded an oscillator that produced 10 mJ, TEM00 300 MHz bandwidth, 75 ns pulses, over a repetition rate of 1-20 Hz, and at a slope efficiency of 2 percent. These techniques were also successfully applied to a YLF oscillator. They may, in part, be adapted for use to unstable resonators.

  11. Hong-Ou-Mandel interference experiment of two independent heralded single photon sources in an optical fiber with birefringence

    NASA Astrophysics Data System (ADS)

    Ma, Tianyi; Zhou, Qiang; Zhang, Wei; Huang, Yidong; Cui, Xiaowei; Lu, Mingquan; Feng, Zhenming

    2012-11-01

    Single photon sources (SPSs) play important roles in quantum communication and quantum information processing. Spontaneous four wave mixing (SFWM) in optical fibers provides a promising way to realize practical heralded single photon sources (HSPSs), since it is compatible with current techniques of optical communications. In this paper, two independent HSPSs at 1.5μm band are realized in one polarization maintaining dispersion shifted fiber (PM-DSF) utilizing its large birefringence. When pulsed pump light passes through an optical fiber, two kinds of SFWM will take place simultaneously. One is scalar processes, in which two annihilated pump photons and generated photon pair are all polarized along the same fiber polarization axis. The other is vector processes, in which two annihilated pump photons are polarized along different fiber polarization axes, either for the two photons of the generated pair. In the PM-DSF, the large birefringence generates obvious walk-off effect on the two pump polarization components, which leads to an effective suppression of the vector processes. Hence, by proper pump polarization, correlated photon pairs (CPPs) with different polarization directions can be generated independently by the two scalar processes, which can be used to realize two independent HSPSs. The indistinguishability of the heralded photons generated by the two independent sources is demonstrated by an experiment of Hong-Ou-Mandel (HOM) interference. Using a fiber coupler as the beam splitter, a visibility of HOM dip of 76% is achieved, showing their potential on quantum information.

  12. Wide-field imaging of birefringent synovial fluid crystals using lens-free polarized microscopy for gout diagnosis

    PubMed Central

    Zhang, Yibo; Lee, Seung Yoon Celine; Zhang, Yun; Furst, Daniel; Fitzgerald, John; Ozcan, Aydogan

    2016-01-01

    Gout is a form of crystal arthropathy where monosodium urate (MSU) crystals deposit and elicit inflammation in a joint. Diagnosis of gout relies on identification of MSU crystals under a compensated polarized light microscope (CPLM) in synovial fluid aspirated from the patient’s joint. The detection of MSU crystals by optical microscopy is enhanced by their birefringent properties. However, CPLM partially suffers from the high-cost and bulkiness of conventional lens-based microscopy, and its relatively small field-of-view (FOV) limits the efficiency and accuracy of gout diagnosis. Here we present a lens-free polarized microscope which adopts a novel differential and angle-mismatched polarizing optical design achieving wide-field and high-resolution holographic imaging of birefringent objects with a color contrast similar to that of a standard CPLM. The performance of this computational polarization microscope is validated by imaging MSU crystals made from a gout patient’s tophus and steroid crystals used as negative control. This lens-free polarized microscope, with its wide FOV (>20 mm2), cost-effectiveness and field-portability, can significantly improve the efficiency and accuracy of gout diagnosis, reduce costs, and can be deployed even at the point-of-care and in resource-limited clinical settings. PMID:27356625

  13. Wide-field imaging of birefringent synovial fluid crystals using lens-free polarized microscopy for gout diagnosis

    NASA Astrophysics Data System (ADS)

    Zhang, Yibo; Lee, Seung Yoon Celine; Zhang, Yun; Furst, Daniel; Fitzgerald, John; Ozcan, Aydogan

    2016-06-01

    Gout is a form of crystal arthropathy where monosodium urate (MSU) crystals deposit and elicit inflammation in a joint. Diagnosis of gout relies on identification of MSU crystals under a compensated polarized light microscope (CPLM) in synovial fluid aspirated from the patient’s joint. The detection of MSU crystals by optical microscopy is enhanced by their birefringent properties. However, CPLM partially suffers from the high-cost and bulkiness of conventional lens-based microscopy, and its relatively small field-of-view (FOV) limits the efficiency and accuracy of gout diagnosis. Here we present a lens-free polarized microscope which adopts a novel differential and angle-mismatched polarizing optical design achieving wide-field and high-resolution holographic imaging of birefringent objects with a color contrast similar to that of a standard CPLM. The performance of this computational polarization microscope is validated by imaging MSU crystals made from a gout patient’s tophus and steroid crystals used as negative control. This lens-free polarized microscope, with its wide FOV (>20 mm2), cost-effectiveness and field-portability, can significantly improve the efficiency and accuracy of gout diagnosis, reduce costs, and can be deployed even at the point-of-care and in resource-limited clinical settings.

  14. Wide-field imaging of birefringent synovial fluid crystals using lens-free polarized microscopy for gout diagnosis.

    PubMed

    Zhang, Yibo; Lee, Seung Yoon Celine; Zhang, Yun; Furst, Daniel; Fitzgerald, John; Ozcan, Aydogan

    2016-01-01

    Gout is a form of crystal arthropathy where monosodium urate (MSU) crystals deposit and elicit inflammation in a joint. Diagnosis of gout relies on identification of MSU crystals under a compensated polarized light microscope (CPLM) in synovial fluid aspirated from the patient's joint. The detection of MSU crystals by optical microscopy is enhanced by their birefringent properties. However, CPLM partially suffers from the high-cost and bulkiness of conventional lens-based microscopy, and its relatively small field-of-view (FOV) limits the efficiency and accuracy of gout diagnosis. Here we present a lens-free polarized microscope which adopts a novel differential and angle-mismatched polarizing optical design achieving wide-field and high-resolution holographic imaging of birefringent objects with a color contrast similar to that of a standard CPLM. The performance of this computational polarization microscope is validated by imaging MSU crystals made from a gout patient's tophus and steroid crystals used as negative control. This lens-free polarized microscope, with its wide FOV (>20 mm(2)), cost-effectiveness and field-portability, can significantly improve the efficiency and accuracy of gout diagnosis, reduce costs, and can be deployed even at the point-of-care and in resource-limited clinical settings. PMID:27356625

  15. A novel micro-processing of waveguide coupler in birefringent crystal by twin tracks of single-scan femtosecond laser writing

    NASA Astrophysics Data System (ADS)

    Cheng, Chen; Vázquez de Aldana, J. R.; Chen, Feng

    2015-07-01

    Through a novel micro-processing mechanism in birefringent crystals proposed in this work, a coupler containing twin depressed cladding waveguides have been achieved in Nd:GdVO4 laser crystals. By employing single-scan of femtosecond laser writing, twin tracks with different depths separated by a distance of 70μm were produced due to the birefringence of Nd:GdVO4 crystal. The adjacent 30μm-diameter cladding waveguides, which consist of a 2×2 coupler with a separation of 70μm in a 4-mm-long crystal sample, were inscribed simultaneously. The ratio of output power division from both waveguides was approximately 10.5:1 at 633nm. Continuous-wave lasing was realized in the waveguide coupler platform under the direct optical pump at 808nm. This work indicates a great potential for femtosecond laser inscribed symmetry structures such as waveguide couplers in birefringent crystals based on the proposed micro-processing mechanism.

  16. A polarisation modulation scheme for measuring vacuum magnetic birefringence with static fields

    NASA Astrophysics Data System (ADS)

    Zavattini, G.; Della Valle, F.; Ejlli, A.; Ruoso, G.

    2016-05-01

    A novel polarisation modulation scheme for polarimeters based on Fabry-Perot cavities is presented. The application to the measurement of the magnetic birefringence of vacuum with the HERA superconducting magnets in the ALPS-II configuration is discussed.

  17. Note: In situ measurement of vacuum window birefringence by atomic spectroscopy.

    PubMed

    Steffen, Andreas; Alt, Wolfgang; Genske, Maximilian; Meschede, Dieter; Robens, Carsten; Alberti, Andrea

    2013-12-01

    We present an in situ method to measure the birefringence of a single vacuum window by means of microwave spectroscopy on an ensemble of cold atoms. Stress-induced birefringence can cause an ellipticity in the polarization of an initially linearly polarized laser beam. The amount of ellipticity can be reconstructed by measuring the differential vector light shift of an atomic hyperfine transition. Measuring the ellipticity as a function of the linear polarization angle allows us to infer the amount of birefringence Δn at the level of 10(-8) and identify the orientation of the optical axes. The key benefit of this method is the ability to separately characterize each vacuum window, allowing the birefringence to be precisely compensated in existing vacuum apparatuses. PMID:24387479

  18. Dispersion of the temperature-noncritical frequency conversion and birefringence in biaxial optical crystals

    SciTech Connect

    Grechin, Sergei G; Dmitriev, Valentin G; Dyakov, Vladimir A; Pryalkin, Vladimir I

    2004-05-31

    Dispersion of the temperature-noncritical frequency conversion (phase matching) and birefringence in biaxial crystals is considered. The possibility of simultaneous realisation of these processes during SHG in a KTP crystal is discussed. (nonlinear optical phenomena)

  19. Note: In situ measurement of vacuum window birefringence by atomic spectroscopy

    SciTech Connect

    Steffen, Andreas; Alt, Wolfgang; Genske, Maximilian; Meschede, Dieter; Robens, Carsten; Alberti, Andrea

    2013-12-15

    We present an in situ method to measure the birefringence of a single vacuum window by means of microwave spectroscopy on an ensemble of cold atoms. Stress-induced birefringence can cause an ellipticity in the polarization of an initially linearly polarized laser beam. The amount of ellipticity can be reconstructed by measuring the differential vector light shift of an atomic hyperfine transition. Measuring the ellipticity as a function of the linear polarization angle allows us to infer the amount of birefringence Δn at the level of 10{sup −8} and identify the orientation of the optical axes. The key benefit of this method is the ability to separately characterize each vacuum window, allowing the birefringence to be precisely compensated in existing vacuum apparatuses.

  20. Proposal for high-birefringent terahertz photonic crystal fiber with all circle air holes

    NASA Astrophysics Data System (ADS)

    Wu, Zhiqing; Zhou, Xiaoyan; Shi, Zhaohua; Xia, Handing; Huang, Jin; Jiang, Xiaodong; Wu, Weidong

    2016-03-01

    A type of high-birefringent terahertz (THz) photonic crystal fiber (PCF) with all circle air holes is proposed. The characteristics including birefringence, dispersion, and confinement loss are numerically analyzed in detail by using the finite element methods. Simulation results show that the proposed THz PCFs exhibit high birefringence on the level of 10-2 in the frequency range of 2 to 4 THz, which is realized by the minor position adjustment of air holes in the first ring of the cladding. We believe that the proposed THz PCFs can be fabricated without complications due to their simple structure. In addition, two porous-core THz PCFs are proposed and the birefringence property is investigated.

  1. Birefringence analysis of a two elliptical cores hollow fiber based on finite element method

    NASA Astrophysics Data System (ADS)

    Tian, Fengjun; Yuan, Libo; Dai, Qian; Liu, Zhihai; Zhang, Jianzhong

    2012-02-01

    We design and fabricate a two elliptical cores hollow optical fiber, which has an about 60μm diameter hollow air hole centrally, a 125μm diameter cladding, two 8μm/4μm (major axis/minor axis) elliptical cores, and a 2μm thickness silica cladding between core layer and air hole. Its mode birefringence is consisted of geometry birefringence and self-stress birefringence. Based on the finite element method the birefringence characteristics are analyzed numerically at 200nm- 1800nm wavelength. We expect that the two elliptical cores hollow fiber has some potential applications in in-fiber interferometers with polarization maintaining, poling fiber and Bio-sensor based on evanescent wave field.

  2. Design of Topas photonic bandgap fiber with high birefringence and low confinement loss

    NASA Astrophysics Data System (ADS)

    Wang, Doudou; Wang, Lili

    2010-09-01

    A highly birefringent hollow-core photonic bandgap fiber based on Topas cyclic olefin copolymer is designed. The rhombic hollow-core with rounded corners is formed by omitting four central air holes of the cladding structure. The guided modes, birefringence and confinement loss of the fiber are investigated by using the full-vector finite element method. A high phase birefringence of the order of 10 -3, a group birefringence of the order of 10 -2 and confinement loss less than 0.1 dB/km are obtained at the central wavelength (1.55 μm) range of the bandgap for fiber with seven rings of air holes in the cladding region.

  3. Analysis of a highly birefringent asymmetric photonic crystal fibre based on a surface plasmon resonance sensor

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Wang, Famei; Zheng, Shijie; Sun, Tao; Lv, Jingwei; Liu, Qiang; Yang, Lin; Mu, Haiwei; Chu, Paul K.

    2016-07-01

    A highly birefringent photonic crystal fibre is proposed and characterized based on a surface plasmon resonance sensor. The birefringence of the sensor is numerically analyzed by the finite-element method. In the numerical simulation, the resonance wavelength can be directly positioned at this birefringence abrupt change point and the depth of the abrupt change of birefringence reflects the intensity of excited surface plasmon. Consequently, the novel approach can accurately locate the resonance peak of the system without analyzing the loss spectrum. Simulated average sensitivity is as high as 1131 nm/RIU, corresponding to a resolution of 1 × 10-4 RIU in this sensor. Therefore, results obtained via the approach not only show polarization independence and less noble metal consumption, but also reveal better performance in terms of accuracy and computation efficiency.

  4. Synthesis and photo-induced birefringence of pyrazoline substituted azo-dyes in PMMA films

    NASA Astrophysics Data System (ADS)

    Jin, Ming; Xin Yang, Qing; Lu, Ran; Yun Pan, Ling; Chong Xue, Peng; Zhao, YingYing

    2003-12-01

    Three push-pull type azo dyes, 4 '-{[(2-hydroxylethyl)methyl]amino}-4-nitroazobenzene (compound I), 1-[4-(4 '-nitrophenyl)-azophenyl]-3,5-biphenyl-2-pyrazoline (compound II) and 1-[4-(4 '-nitrophenyl)-azophenyl]-3-(3 '-trifluoromethyl)-phenyl-5-phenyl-2-pyrazoline (compound III) were synthesized. The cis- trans isomerization process and polarized photoinduced birefringence of those azo dyes doped PMMA films were investigated. It was found that the rise and relaxation process of birefringence signals were fit with biexponential functions and the molecular structures have effects on their photo-induced birefringence. This suggests that the three films have similar storage speed when the laser intensity is high enough. Compound III, which has the biggest substituent, has the largest long-term storage ability and can even keep 90% of its saturated birefringence.

  5. Electric Birefringence: A Simple Apparatus for Determining Physical Parameters of Macromolecules and Colloids.

    ERIC Educational Resources Information Center

    Trimm, Harold H.; And Others

    1984-01-01

    Describes a birefringence apparatus that can be assembled for less than $100 and can be used to measure both the dimensions and dipole moments of many macromolecules. Details are given of the construction and manipulation of the apparatus. (JN)

  6. Quantum-electrodynamical birefringence vanishing in a thermal relativistic pair plasma.

    PubMed

    Huang, Y S

    2015-01-01

    Quantum electrodynamical (QED) birefringence in a thermal relativistic pair plasma with the presence of the strong crossed field: E0 ⊥ B0, is proposed and investigated. We clarify the coupling relationship and competition between the QED effect and the plasma collective effect and find the critical condition that makes the birefringence vanish. In a relative weak electromagnetic field, the birefringence is dominated by the coupling of the QED-effect, the collective effect and the E0 × B0 drift effect. In a relative strong electromagnetic field, we obtain the formulations stating the competition between the QED effect and the collective effect and then the critical conditions so that they are canceled with each other and the birefringence vanishes. With our results, a new possible scheme is proposed to estimate the thickness of the magnetosphere in a millisecond pulsar and the plasma density of a pulsar, if the magnetic field is known beforehand. PMID:26522493

  7. Quantum-electrodynamical birefringence vanishing in a thermal relativistic pair plasma

    PubMed Central

    Huang, Y. S.

    2015-01-01

    Quantum electrodynamical (QED) birefringence in a thermal relativistic pair plasma with the presence of the strong crossed field: , is proposed and investigated. We clarify the coupling relationship and competition between the QED effect and the plasma collective effect and find the critical condition that makes the birefringence vanish. In a relative weak electromagnetic field, the birefringence is dominated by the coupling of the QED-effect, the collective effect and the drift effect. In a relative strong electromagnetic field, we obtain the formulations stating the competition between the QED effect and the collective effect and then the critical conditions so that they are canceled with each other and the birefringence vanishes. With our results, a new possible scheme is proposed to estimate the thickness of the magnetosphere in a millisecond pulsar and the plasma density of a pulsar, if the magnetic field is known beforehand. PMID:26522493

  8. Planar Poincare Chart for predicting the change of polarization state in the elliptical birefringent material

    NASA Technical Reports Server (NTRS)

    Tedjojuwono, Ken K.; Hunter, William W., Jr.; Ocheltree, Stewart L.

    1989-01-01

    The Planar Poincare Chart has been developed as a complete planar equivalence of the Poincare sphere. The four main parameters of the light wave represented by the chart are drawn separately on two parts, so that any orientation of the optical component can be shown on the chart. The Planar Poincare Chart can be used to graphically design and analyze the polarization dependent components, e.g. to predict the polarization change in the birefringent material. Depending on how the chart is projected, different types of birefringent materials can be investigated. Previously, the chart for linear and circular birefringent materials has been reported. In a more general case, a chart for elliptical birefringent material is developed where the linear and circular cases can be considered as special cases.

  9. Planar Poincare Chart for predicting the change of polarization state in the elliptical birefringent material

    NASA Technical Reports Server (NTRS)

    Hunter, William W., Jr.; Ocheltree, Stewart L.; Tedjojuwono, Ken K.

    1988-01-01

    The Planar Poincare Chart has been developed as a complete planar equivalence of the Poincare sphere. The four main parameters of the light wave represented by the chart are drawn separately on two parts, so that any orientation of the optical component can be shown on the chart. The Planar Poincare Chart can be used to graphically design and analyze the polarization dependent components, e.g. to predict the polarization change in the birefringent material. Depending on how the chart is projected, different types of birefringent materials can be investigated. The chart for linear and circular birefringent materials has been reported previously. In a more general case, a chart for elliptical birefringent material is developed where the linear and circular cases can be considered as special cases.

  10. Mode-splitting cloning in birefringent fiber Bragg grating ring resonators.

    PubMed

    Campanella, C E; Malara, P; Campanella, C M; Giove, F; Dunai, M; Passaro, V M N; Gagliardi, G

    2016-06-15

    In this Letter, we report the theoretical model and the experimental evidence of a mode-splitting cloning effect due to the resonant coupling between modes having different polarizations in weakly birefringent fiber Bragg grating (FBG) ring resonators. This modal coupling depends on the fiber birefringence and the FBG reflectivity. In the ideal case of the absence of birefringence, a single split-mode resonant structure can be observed in the resonator transmission spectrum due to the degeneracy removal of the two counter-propagating modes. In the presence of FBG birefringence, a secondary split doublet resulting in a clone of the initial one is generated. The described effect can be exploited for spectroscopic-sensing applications based on more complex split-mode dynamics. PMID:27304260

  11. Quantitative Assessment of Birefringent Skin Structures in Scattered Light Confocal Imaging Using Radially Polarized Light

    PubMed Central

    Varghese, Babu; Verhagen, Rieko; Hussain, Altaf; Boudot, Clemence; Tai, Qiangqiang; Ding, Siqi; Holz, Jasmin Alexandra; Uzunbajakava, Natallia Eduarda

    2013-01-01

    The polarization characteristics of birefringent tissues could be only partially obtained using linearly polarized light in polarization sensitive optical imaging. Here we analyze the change in polarization of backscattered light from birefringent structures versus the orientations of the incident polarizations using linearly, circularly and radially polarized light in a cross-polarized confocal microscope. A spatially variable retardation plate composed of eight sectors of λ/2 wave plates was used to transform linearly polarized light into a radially polarized light. Based on the experimental data obtained from ex-vivo measurements on human scalp hairs and in-vivo measurements on hair and skin, we exemplify that the underestimation of the birefringence content resulting from the orientation related effects associated with the use of linearly polarized light for imaging tissues containing wavy birefringent structures could be minimized by using radially polarized light. PMID:24048342

  12. Accurate and quantitative polarization-sensitive OCT by unbiased birefringence estimator with noise-stochastic correction

    NASA Astrophysics Data System (ADS)

    Kasaragod, Deepa; Sugiyama, Satoshi; Ikuno, Yasushi; Alonso-Caneiro, David; Yamanari, Masahiro; Fukuda, Shinichi; Oshika, Tetsuro; Hong, Young-Joo; Li, En; Makita, Shuichi; Miura, Masahiro; Yasuno, Yoshiaki

    2016-03-01

    Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT that contrasts the polarization properties of tissues. It has been applied to ophthalmology, cardiology, etc. Proper quantitative imaging is required for a widespread clinical utility. However, the conventional method of averaging to improve the signal to noise ratio (SNR) and the contrast of the phase retardation (or birefringence) images introduce a noise bias offset from the true value. This bias reduces the effectiveness of birefringence contrast for a quantitative study. Although coherent averaging of Jones matrix tomography has been widely utilized and has improved the image quality, the fundamental limitation of nonlinear dependency of phase retardation and birefringence to the SNR was not overcome. So the birefringence obtained by PS-OCT was still not accurate for a quantitative imaging. The nonlinear effect of SNR to phase retardation and birefringence measurement was previously formulated in detail for a Jones matrix OCT (JM-OCT) [1]. Based on this, we had developed a maximum a-posteriori (MAP) estimator and quantitative birefringence imaging was demonstrated [2]. However, this first version of estimator had a theoretical shortcoming. It did not take into account the stochastic nature of SNR of OCT signal. In this paper, we present an improved version of the MAP estimator which takes into account the stochastic property of SNR. This estimator uses a probability distribution function (PDF) of true local retardation, which is proportional to birefringence, under a specific set of measurements of the birefringence and SNR. The PDF was pre-computed by a Monte-Carlo (MC) simulation based on the mathematical model of JM-OCT before the measurement. A comparison between this new MAP estimator, our previous MAP estimator [2], and the standard mean estimator is presented. The comparisons are performed both by numerical simulation and in vivo measurements of anterior and

  13. Interaction of neutrons with a birefringent medium moving with an acceleration

    NASA Astrophysics Data System (ADS)

    Frank, A. I.

    2016-04-01

    Recent experiments demonstrated that the energy of a neutron traversing an accelerated sample of a refractive medium changes. Later, it was realized that such an accelerated-medium effect (AME) is quite a general phenomenon. This paper discusses some special features of the effect for a birefringent medium. In this case, AME shows quite new features. In neutron optics, where birefringence is due to the spin dependence of the refractive index, AME results in a nonstationary state with a precessing spin.

  14. Light-induced rotations of chiral birefringent microparticles in optical tweezers.

    PubMed

    Donato, M G; Mazzulla, A; Pagliusi, P; Magazzù, A; Hernandez, R J; Provenzano, C; Gucciardi, P G; Maragò, O M; Cipparrone, G

    2016-01-01

    We study the rotational dynamics of solid chiral and birefringent microparticles induced by elliptically polarized laser light in optical tweezers. We find that both reflection of left circularly polarized light and residual linear retardance affect the particle dynamics. The degree of ellipticity of laser light needed to induce rotations is found. The experimental results are compared with analytical calculations of the transfer of angular moment from elliptically polarized light to chiral birefringent particles. PMID:27601200

  15. Investigating compression failure mechanisms in composite laminates with a transparent fiberglass-epoxy birefringent materials

    NASA Technical Reports Server (NTRS)

    Shuart, M. J.; Williams, J. G.

    1984-01-01

    The response and failure of a + or - 45s class laminate was studied by transparent fiberglass epoxy composite birefringent material. The birefringency property allows the laminate stress distribution to be observed during the test and also after the test if permanent residual stresses occur. The location of initial laminate failure and of the subsequent failure propagation are observed through its transparency characteristics. Experimental results are presented.

  16. Light-induced rotations of chiral birefringent microparticles in optical tweezers

    PubMed Central

    Donato, M. G.; Mazzulla, A.; Pagliusi, P.; Magazzù, A.; Hernandez, R. J.; Provenzano, C.; Gucciardi, P. G.; Maragò, O. M.; Cipparrone, G.

    2016-01-01

    We study the rotational dynamics of solid chiral and birefringent microparticles induced by elliptically polarized laser light in optical tweezers. We find that both reflection of left circularly polarized light and residual linear retardance affect the particle dynamics. The degree of ellipticity of laser light needed to induce rotations is found. The experimental results are compared with analytical calculations of the transfer of angular moment from elliptically polarized light to chiral birefringent particles. PMID:27601200

  17. Birefringence of the central cornea in children assessed with scanning laser polarimetry

    NASA Astrophysics Data System (ADS)

    Irsch, Kristina; Shah, Ashesh A.

    2012-08-01

    Corneal birefringence is a well-known confounding factor with all polarization-sensitive technology used for retinal scanning and other intraocular assessment. It has been studied extensively in adults, but little is known regarding age-related differences. Specifically, no information is available concerning corneal birefringence in children. For applications that are geared towards children, such as retinal birefringence scanning for strabismus screening purposes, it is important to know the expected range of both corneal retardance and azimuth in pediatric populations. This study investigated central corneal birefringence in children (ages three and above), by means of scanning laser polarimetry (GDx-VCC™, Carl Zeiss Meditec, Inc.). Children's measures of corneal retardance and azimuth were compared with those obtained in adults. As with previous studies in adults, corneal birefringence was found to vary widely in children, with corneal retardance ranging from 10 to 77 nm, and azimuth (slow axis) ranging from -11° to 71° (measured nasally downward). No significant differences in central corneal birefringence were found between children and adults, nor were significant age-related differences found in general. In conclusion, establishing knowledge of the polarization properties of the central cornea in children allows better understanding, exploitation, or bypassing of these effects in new polarization-sensitive pediatric ophthalmic applications.

  18. Classification of birefringence in mode-locked fiber lasers using machine learning and sparse representation.

    PubMed

    Fu, Xing; Brunton, Steven L; Nathan Kutz, J

    2014-04-01

    It has been observed that changes in the birefringence, which are difficult or impossible to directly measure, can significantly affect mode-locking in a fiber laser. In this work we develop techniques to estimate the effective birefringence by comparing a test measurement of a given objective function against a learned library. In particular, a toroidal search algorithm is applied to the laser cavity for various birefringence values by varying the waveplate and polarizer angles at incommensurate angular frequencies, thus producing a time-series of the objective function. The resulting time series, which is converted to a spectrogram and then dimensionally reduced with a singular value decomposition, is then labelled with the corresponding effective birefringence and concatenated into a library of modes. A sparse search algorithm (L(1)-norm optimization) is then applied to a test measurement in order to classify the birefringence of the fiber laser. Simulations show that the sparse search algorithm performs very well in recognizing cavity birefringence even in the presence of noise and/or noisy measurements. Once classified, the wave plates and polarizers can be adjusted using servo-control motors to the optimal positions obtained from the toroidal search. The result is an efficient, self-tuning laser. PMID:24718230

  19. Quantification of birefringence readily measures the level of muscle damage in zebrafish

    SciTech Connect

    Berger, Joachim; Sztal, Tamar; Currie, Peter D.

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer Report of an unbiased quantification of the birefringence of muscle of fish larvae. Black-Right-Pointing-Pointer Quantification method readily identifies level of overall muscle damage. Black-Right-Pointing-Pointer Compare zebrafish muscle mutants for level of phenotype severity. Black-Right-Pointing-Pointer Proposed tool to survey treatments that aim to ameliorate muscular dystrophy. -- Abstract: Muscular dystrophies are a group of genetic disorders that progressively weaken and degenerate muscle. Many zebrafish models for human muscular dystrophies have been generated and analysed, including dystrophin-deficient zebrafish mutants dmd that model Duchenne Muscular Dystrophy. Under polarised light the zebrafish muscle can be detected as a bright area in an otherwise dark background. This light effect, called birefringence, results from the diffraction of polarised light through the pseudo-crystalline array of the muscle sarcomeres. Muscle damage, as seen in zebrafish models for muscular dystrophies, can readily be detected by a reduction in the birefringence. Therefore, birefringence is a very sensitive indicator of overall muscle integrity within larval zebrafish. Unbiased documentation of the birefringence followed by densitometric measurement enables the quantification of the birefringence of zebrafish larvae. Thereby, the overall level of muscle integrity can be detected, allowing the identification and categorisation of zebrafish muscle mutants. In addition, we propose that the establish protocol can be used to analyse treatments aimed at ameliorating dystrophic zebrafish models.

  20. Interrogation and mitigation of polarization effects for standard and birefringent FBGs

    NASA Astrophysics Data System (ADS)

    Ibrahim, Selwan K.; Van Roosbroeck, Jan; O'Dowd, John A.; Van Hoe, Bram; Lindner, Eric; Vlekken, Johan; Farnan, Martin; Karabacak, Devrez M.; Singer, Johannes M.

    2016-05-01

    Optical sensors based on Fiber Bragg Gratings (FBGs) are used in several applications and industries. Several inscription techniques and type of fibers can be used. However, depending on the writing process, type of fiber used and the packaging of the sensor a Polarization Dependent Frequency Shift (PDFS) can often be observed with polarized tunable laser based optical interrogators. Here we study the PDFS of the FBG peak for the different FBG types. A PDFS of <1pm up to >20pm was observed across the FBGs. To mitigate and reduce this effect we propose a polarization mitigation technique which relies on a synchronous polarization switch to reduce the effect typically by a factor greater than 4. In other scenarios the sensor itself is designed to be birefringent (Bi-FBG) to allow pressure and/or simultaneous temperature and strain measurements. Using the same polarization switch we demonstrate how we can interrogate the Bi-FBGs with high accuracy to enable high performance of such sensors to be achievable.

  1. Research on the detection system of liquid concentration base on birefringence light transmission method

    NASA Astrophysics Data System (ADS)

    Li, Tianze; Zhang, Xia; Hou, Luan; Jiang, Chuan

    2010-10-01

    The characteristics of the beam transmitting in the optical fiber and the liquid medium are analyzed in this paper. On this basis, a new type of semiconductor optical position sensitive detector is used for a receiving device, a light transmission method of birefringence is presented,and a set of opto-electrical detection system which is applied to detect liquid concentration is designed. The system is mainly composed of semiconductor lasers,optical systems, Psd signal conditioning circuit, Single-chip System, A/D conversion circuit and display circuit. Through theoretical analysis and experimental simulations, the accuracy of this system has been verified. Some main factors affecting the test results are analyzed detailedly in this paper. The experiments show that the temperature drift and the light intensity have a very small impact on this system. The system has some advantages, such as the simple structure, high sensitivity, good stability, fast response time, high degree of automation, and so on. It also can achieve the real-time detection of liquid concentration conveniently and accurately. The system can be widely applied in chemical, food, pharmacy and many other industries. It has broad prospects of application.

  2. Analysis on the effect of extinction ratio in birefringent measurement by phase-stepping method

    NASA Astrophysics Data System (ADS)

    Zhang, Xusheng; Wang, Haoyu; He, Chuan

    2012-11-01

    The theoretical and experimental analysis on the effects of extinction ratios of linear polarizer and analyzer in the measurement of birefringent retardance by a five-step phase-shifting method based on the plane polariscope is presented. Stokes vector and Mueller matrix are the tools used to perform this theoretical analysis. The theoretical analysis show that the coefficients of extinction ratios of linear polarizer and analyzer in plane polariscopic configuration can be eliminated by phase shifting and will not introduce errors with our proposed five-step method. A mica quarter waveplate with previously given phase retardation is tested and evaluated. The experimental comparison has been made between the calcite Glan-Thompson based system with extremely high extinction ratios and plastic Polaroid film based system with relatively lower extinction ratios. The experimental results show that there is no significant difference between the measured values from these two systems, which agrees well with the conclusion of theoretical analysis. Also, good experimental accuracy and repeatability are achieved as well by the proposed five-step phase-shifting method.

  3. Localization-length calculations in alternating metamaterial-birefringent disordered layered stacks

    NASA Astrophysics Data System (ADS)

    del Barco, O.; Gasparian, V.; Gevorkian, Zh.

    2015-06-01

    A detailed theoretical and numerical analysis of the localization length in alternating metamaterial-birefringent random layered stacks, under uncorrelated thickness disorder, has been performed. Similar structures have recently been reported to suppress the Brewster delocalization for p -polarized light when "standard" isotropic layers (with a positive index of refraction) are considered instead of metamaterial layers, providing a generic means to produce polarization-insensitive, broadband reflections. However, this enhancement of localization is valid for short wavelengths λ compared to the mean layer thickness a0. At higher wavelengths, we recover the Brewster anomalies for p -polarized states impeding a remarkable localization of light. To achieve a better localization for a wider range of wavelengths, we replaced the conventional isotropic layers by negative-index metamaterials presenting low losses and constant index of refraction over the near-infrared range. As a result, our numerical calculations exhibit a linear dependence of the localization length on λ (in the region 5 <λ /a0<60 ), reducing the Brewster anomalies by more than two orders of magnitude with respect to the standard isotropic scheme at oblique incidence. This enhancement of localization is practically independent of the thickness disorder kind and is also held under weak refractive-index disorder.

  4. Optimization of particle size for high birefringence and fast switching time in electro-optical switching of graphene oxide dispersions.

    PubMed

    Ahmad, R T M; Hong, Seung-Ho; Shen, Tian-Zi; Song, Jang-Kun

    2015-02-23

    In order to use graphene oxide (GO) dispersions for electro-optical applications, both a high GO concentration and a high electrical sensitivity are essential; however, these have not been achieved to date. Here, we report that by optimizing the mean size of GO particles to approximately 0.5 μm, one can obtain a high GO concentration of up to 2 wt% and high electrical sensitivity simultaneously. By reducing the mean GO-particle size, the interparticle interaction and the rotational viscosity can be significantly reduced, and a high-concentration isotropic phase can be obtained. As a result, the maximum birefringence increases and the dynamic response becomes faster. However, further decrease of the mean size below 0.1 μm causes a decrease in the anisotropy of electrical polarizability, resulting in the reduction of the electrical sensitivity of GO dispersions. PMID:25836480

  5. Extension of the hole-drilling method to birefringent composites

    NASA Technical Reports Server (NTRS)

    Prabhakaran, R.

    1982-01-01

    A complete stress analysis and reliable failure criteria are essential for important structural applications of composites in order to fully utilize their unique properties. The inhomogeneity, anisotropy and inelasticity of many composites make the use of experimental methods indispensable. Among the experimental techniques, transmission photoelasticity has been extended to birefringent composites in recent years. The extension is not straight-forward, in view of the complex nature of the photoelastic response of such model materials. This paper very briefly reviews the important developments in the subject and then describes the theoretical basis for a new method of determining the individual values of principal stresses in composite models. The method consists in drilling very small holes at points where the state of stress has to be determined. Experiments are then described which verify the theoretical predictions. The limitations of the method are pointed out and it is concluded that valuable information concerning the state of stress in a composite model can be obtained through the suggested method.

  6. Strain-induced birefringence in GaAs

    SciTech Connect

    Raynolds, J.E.; Levine, Z.H.; Wilkins, J.W.

    1995-04-15

    We present the results of density-functional calculations of the dielectric function and the photoelastic tensor---the susceptibility for strain-induced birefringence---in GaAs for photon frequencies below the direct band gap. These calculations were performed in the Kohn-Sham local-density approximation in a pseudopotential/plane-wave scheme which includes local-field effects and self-energy corrections. We find that traditional special-points integration methods are inadequate for performing the Brillouin-zone integrals involved in computing the photoelastic tensor. Very high resolution of the critical point at {ital k}=0 is needed to obtain even the correct {ital qualitative} behavior of the photoelastic tensor. Accurate expansions of the integrand in spherical harmonics for small {ital k} and plane waves elsewhere in the Brillouin zone were obtained and an integration approach which correctly integrates the expansions was used. Dramatic improvement in the qualitative frequency dispersion of the photoelastic tensor, in comparison with experiments, is obtained despite a large (50%) shift of the static value away from the measurement. We also present the result of a calculation of the internal strain relaxation associated with strains along the bonding [111] direction. These results are in excellent agreement with two previous {ital ab} {ital initio} calculations and with recent measurements.

  7. Measurement of birefringence for optical recording disk substrates

    NASA Technical Reports Server (NTRS)

    Fu, Hong; Sugaya, S.; Erwin, J. K.; Goodman, T.; Yan, Z.; Tang, W. J.; Mansuripur, M.

    1993-01-01

    The birefringence of bare and coated substrates for magneto-optical recording is experimentally investigated using ellipsometry at the wavelengths of 632.8 nm and 780 nm. The rotation and ellipticity of the polarization state of the reflected or transmitted light is measured for different incident angles and different orientations of the incident linear polarization. The measured data is then fitted by a computer program which solves the Maxwell equations for the plane-wave propagation in a multilayer structure and minimizes the error between the measured and calculated data by adjusting the unknown parameters of the multilayer. This approach enables us to determine orientations of the three principal axes in the substrate and the corresponding refractive indices. A special feature of our ellipsometers is that a glass hemisphere is placed in contact with the substrate, which eliminates the refraction of the incident light and enables a maximum propagation angle of 70 degrees (with respect to the normal) in the substrate. This increases the sensitivity of the measurement. Certain anomalies were observed, which we believe are associated with the presence of grooves on these substrates.

  8. Imaging linear birefringence and dichroism in cerebral amyloid pathologies

    PubMed Central

    Jin, Lee-Way; Claborn, Kacey A.; Kurimoto, Miki; Geday, Morten A.; Maezawa, Izumi; Sohraby, Faranak; Estrada, Marcus; Kaminksy, Werner; Kahr, Bart

    2003-01-01

    New advances in polarized light microscopy were used to image Congo red-stained cerebral amyloidosis in sharp relief. The rotating-polarizer method was used to separate the optical effects of transmission, linear birefringence, extinction, linear dichroism, and orientation of the electric dipole transition moments and to display them as false-color maps. These effects are typically convolved in an ordinary polarized light microscope. In this way, we show that the amyloid deposits in Alzheimer's disease plaques contain structurally disordered centers, providing clues to mechanisms of crystallization of amyloid in vivo. Comparisons are made with plaques from tissues of subjects having Down's syndrome and a prion disease. In plaques characteristic of each disease, the Congo red molecules are oriented radially. The optical orientation in amyloid deposited in blood vessels from subjects having cerebral amyloid angiopathy was 90° out of phase from that in the plaques, suggesting that the fibrils run tangentially with respect to the circumference of the blood vessels. Our result supports an early model in which Congo red molecules are aligned along the long fiber axis and is in contrast to the most recent binding models that are based on computation. This investigation illustrates that the latest methods for the optical analysis of heterogeneous substances are useful for in situ study of amyloid. PMID:14668440

  9. Contribution of lone-pairs to birefringence affected by the Pb(II) coordination environment: a DFT investigation.

    PubMed

    Jing, Qun; Yang, Zhihua; Pan, Shilie; Xue, Dongfeng

    2015-09-14

    Pb(II) cations have long been associated with lone-pairs which can help to enhance the optical anisotropic birefringence. In this paper, the contribution of lead cations to birefringence has been investigated using first-principles and real-space atom-cutting methods. The results show that the contribution of lead cations to birefringence is determined by the degree of stereochemical activity, which is affected by the coordination environment of lead cations. PMID:26234398

  10. Analysis of birefringence in magneto-optical waveguides based on nanoparticles doped sol-gel matrix with an optimized substrate

    NASA Astrophysics Data System (ADS)

    Lebbal, M. R.; Boumaza, T.; Bouchemat, M.

    2015-01-01

    The elimination of birefringence remains a key challenge in integrated optical systems. In this work, we present birefringence study based on the controlling of layer thickness of planar waveguides, using deposited layers based on magnetic nanoparticles. The birefringence can be reduced with a planar device, depending on a glass substrate. The simulation carried out by MATLAB allowed us to deduce the conditions to decrease the phase mismatch and increase the conversion ratio of modes.

  11. Photonic approach for microwave frequency measurement with adjustable measurement range and resolution using birefringence effect in highly non-linear fiber.

    PubMed

    Feng, Danqi; Xie, Heng; Qian, Lifen; Bai, Qinhong; Sun, Junqiang

    2015-06-29

    We experimentally demonstrate a novel approach for microwave frequency measurement utilizing birefringence effect in the highly non-linear fiber (HNLF). A detailed theoretical analysis is presented to implement the adjustable measurement range and resolution. By stimulating a complementary polarization-domain interferometer pair in the HNLF, a mathematical expression that relates the microwave frequency and amplitude comparison function is developed. We carry out a proof-to-concept experiment. A frequency measurement range of 2.5-30 GHz with a measurement error within 0.5 GHz is achieved except 16-17.5 GHz. This method is all-optical and requires no high-speed electronic components. PMID:26191769

  12. Structural Design Parameters for Highly Birefringent Coordination Polymers.

    PubMed

    Thompson, John R; Katz, Michael J; Williams, Vance E; Leznoff, Daniel B

    2015-07-01

    A series of coordination polymer materials incorporating the highly anisotropic 2-(2-pyridyl)-1,10-phenanthroline (phenpy) building block have been synthesized and structurally characterized. M(phenpy)[Au(CN)2]2 (M = Cd, Mn) are isostructural and form a 1-D chain through bridging [Au(CN)2](-) units and extend into a 2-D sheet through aurophilic interactions. M(phenpy)(H2O)[Au(CN)2]2·2H2O (M = Cd, Mn, and Zn) are also isostructural but differ from the first set via the inclusion of a water molecule into the coordination sphere, resulting in a 1-D topology through aurophilic interactions. In(phenpy)(Cl)2[Au(CN)2]·0.5H2O forms a dimer through bridging chlorides and contains a free [Au(CN)2](-) unit. In the plane of the primary crystal growth direction, the birefringence values (Δn) of 0.37(2) (Cd(phenpy)[Au(CN)2]2), 0.50(3) (In(phenpy)(Cl)2[Au(CN)2]·0.5H2O), 0.56(3) and 0.59(6) (M(phenpy)(H2O)[Au(CN)2]2·2H2O M = Cd and Zn, respectively) were determined. β, a structural parameter defined by phenpy units rotated in the A-C plane relative to the light propagation (C) direction, was found to correlate to Δn magnitudes. The addition of a carbon-carbon double bond to terpy has increased the molecular polarizability anisotropy of the building block, and all structures have reduced deviation from planarity in comparison to terpy and terpy derivative structures, leading to these higher Δn values, which are among the highest reported for crystalline solids. PMID:26098267

  13. Birefringence imaging of posterior eye by multi-functional Jones matrix optical coherence tomography.

    PubMed

    Sugiyama, Satoshi; Hong, Young-Joo; Kasaragod, Deepa; Makita, Shuichi; Uematsu, Sato; Ikuno, Yasushi; Miura, Masahiro; Yasuno, Yoshiaki

    2015-12-01

    A clinical grade prototype of posterior multifunctional Jones matrix optical coherence tomography (JM-OCT) is presented. This JM-OCT visualized depth-localized birefringence in addition to conventional cumulative phase retardation imaging through local Jones matrix analysis. In addition, it simultaneously provides a sensitivity enhanced scattering OCT, a quantitative polarization uniformity contrast, and OCT-based angiography. The probe beam is at 1-μm wavelength band. The measurement speed and the depth-resolution were 100,000 A-lines/s, and 6.6 μm in tissue, respectively. Normal and pathologic eyes are examined and several clinical features are revealed, which includes high birefringence in the choroid and lamina cribrosa, and birefringent layered structure of the sclera. The theoretical details of the depth-localized birefringence imaging and conventional phase retardation imaging are formulated. This formulation indicates that the birefringence imaging correctly measures a depth-localized single-trip phase retardation of a tissue, while the conventional phase retardation can provide correct single-trip phase retardation only for some specific types of samples. PMID:26713208

  14. Modeling the corneal birefringence of the eye toward the development of a polarimetric glucose sensor

    NASA Astrophysics Data System (ADS)

    Malik, Bilal H.; Coté, Gerard L.

    2010-05-01

    Optical polarimetry for monitoring glucose concentration in the aqueous humor of the eye as a potential noninvasive means of assessing blood glucose has promise, but the realization of such an approach has been limited by noise from time-varying corneal birefringence due to motion artifact. Modeling the corneal birefringence of the eye is critically important toward understanding the overall effect of this noise source compared to other changes in the signal, and can aid in design of the polarimetric system. To this end, an eye model is introduced in this work that includes spatially varying birefringence properties of the cornea. The degree of birefringence and the fast axis orientation is calculated as a function of beam position on the anterior chamber. It is shown that the minimum change in polarization vector orientation occurs for beam position near the midpoint between the corneal apex and limbus. In addition, the relative wavelength independence of motion artifact is shown in the same region. The direct consequence of these findings are that a multiwavelength polarimetric system can potentially be utilized to eliminate the effect of time-varying corneal birefringence, and that eye coupling is optimal at the midpoint between the apex and limbus.

  15. Orientation birefringence of cross-linked rubber containing low-mass compound

    NASA Astrophysics Data System (ADS)

    Kiyama, Ayumi; Nobukawa, Shogo; Yamauchi, Masayuki

    2015-05-01

    Molecular orientation of low-mass compounds (LMCs) in a cross-linked rubber is studied in order to obtain the basic information on the dynamics of LMC molecules in a polymer beyond the glass transition temperature. A small amount of LMCs such as 4-cyano-4'-pentylbiphenyl (5CB), tricresylphosphate (TCP), and styrene-based tackifier (TF) is added into polybutadiene rubber (BR). After cross-linking reaction, the sheet samples are used to evaluate the orientation birefringence during stretching and stress relaxation. The rectangular films, cut out from the cross-linked sheets, are set in a uniaxial stretching machine equipped with an optical system to measure both birefringence and tensile stress simultaneously. It is confirmed that orientation birefringence is proportional to the stress for not only pure cross-linked BR, but also cross-linked BR containing an LMC in a wide range of strain. Even after stretching, the birefringence does not change as far as the sample is kept at a constant strain. The results suggest that the LMC molecules are forced to orient with polymer chains by the strong intermolecular orientation correlation. Because of the LMC orientation, the stress-optical coefficient CR is enhanced by the addition of 5CB and TCP, but depressed by TF. Therefore, the LMC doping can be used to control the birefringence of a retardation film.

  16. At-sea Validation of a Birefringence Method for Determining PIC Concentrations in Seawater

    NASA Astrophysics Data System (ADS)

    Guay, C. K.; Bishop, J. K.

    2001-12-01

    We have previously described a spectrophotometer-based method for making optical measurements of particulate inorganic carbon (PIC) in seawater. This method, based on the extreme birefringence of calcium carbonate (CaCO3) relative to other major components of marine particulate matter, was developed in the laboratory using sample suspensions prepared from calcareous marine sediment material and varying amounts of non-birefringent diatomaceous earth. Here we report the first successful measurements of birefringence signals in natural seawater samples, which were obtained during a recent cruise to the North Pacific off the California coast. The spectrophotometer-based method was used onboard to measure PIC in samples collected from Niskin bottle casts in a variety of environments (nearshore to open ocean, eutrophic to oligotrophic). These samples contained a diverse mixture of particles, including calcareous, siliceous and organic material. Birefringence signals clearly above the detection level were observed in several samples, with the strongest signals occurring in productive surface waters off Point Concepcion. The spectrophotometer-based method was validated against PIC concentrations determined by chemical analysis of particulate matter collected by filtration of the Niskin bottle samples and from large-volume (1000's of L) in situ filtration performed immediately after the Niskin casts. In addition, these data were compared with in situ birefringence measurements made using a prototype profiling PIC sensor deployed on the rosette during the Niskin casts.

  17. Channelled spectrum method for birefringence dispersion measurement of anisotropic Mylar film

    NASA Astrophysics Data System (ADS)

    Sanaâ, F.; Palierne, J. F.; Gharbia, M.

    2016-07-01

    A convenient and accurate interferometric technique for measuring the birefringence dispersion of anisotropic Mylar film according to a continuous spectral range of wavelengths in the ultraviolet, visible and near infrared region, using the so called "Channelled Spectrum" method is described. The technique proposed here consists of considering all the experimental data, not only the minima of the transmitted light obtained after recording the transmitted light that travelled a Mylar film sandwiched between two crossed polarizers. Furthermore, we are able to measure the transmission coefficients of the polarizers, the absorption of the Mylar sheet, and other parameters involved in the experiment by using a spectroscopic detection. Thus, the transmission of the Mylar sheet vs wavelength is deduced. Using the dispersion of the optical birefringence given by the birefringence dispersion theory for uniaxial organic compounds ie the one band, three-band, and Cauchy models, and by applying a nonlinear fitting procedure on the recorded experimental data, we have obtained the parameters involved in the expressions of the optical birefringence and we have computed the optical birefringence of the Mylar film vs wavelengths. In the visible and near-infrared regions, all models give excellent fits to the experimental data. In the UV region, the three-band model considers the resonance effect. Thus, in the near-resonance region the results from the three-band model are more accurate.

  18. In-vivo depth-resolved birefringence measurements of the human retina

    NASA Astrophysics Data System (ADS)

    Cense, Barry; Chen, Teresa; Park, Boris H.; Pierce, Mark C.; de Boer, Johannes F.

    2002-06-01

    Glaucoma causes irreversible damage to nerves in the retinal nerve fiber layer. A technique that could measure both the condition and thickness of the retinal nerve fiber layer (RNFL) would be very useful for the early detection and treatment of glaucoma. Polarization Sensitive Optical Coherence Tomography (PS-OCT) is a modality that measures the depth resolved optical birefringence of biological tissue. Since damage to the nerve fiber layer could decrease its birefringence, PS-OCT has the potential to enhance specificity in determining RNFL thickness and integrity in OCT images. In order to measure the RNFL birefringence on humans in vivo, a fiber-based PS-OCT set-up was built with which quasi real time images of the human retina were made. Preliminary measurements on a healthy retina show that the birefringence of the RNFL around the optic nerve head was equal to 34+/- 3 degree(s)/100 micrometers . In conclusion, to our knowledge, we present the first depth resolved birefringence measurements of the human RNFL in vivo.

  19. Birefringence imaging of posterior eye by multi-functional Jones matrix optical coherence tomography

    PubMed Central

    Sugiyama, Satoshi; Hong, Young-Joo; Kasaragod, Deepa; Makita, Shuichi; Uematsu, Sato; Ikuno, Yasushi; Miura, Masahiro; Yasuno, Yoshiaki

    2015-01-01

    A clinical grade prototype of posterior multifunctional Jones matrix optical coherence tomography (JM-OCT) is presented. This JM-OCT visualized depth-localized birefringence in addition to conventional cumulative phase retardation imaging through local Jones matrix analysis. In addition, it simultaneously provides a sensitivity enhanced scattering OCT, a quantitative polarization uniformity contrast, and OCT-based angiography. The probe beam is at 1-μm wavelength band. The measurement speed and the depth-resolution were 100,000 A-lines/s, and 6.6 μm in tissue, respectively. Normal and pathologic eyes are examined and several clinical features are revealed, which includes high birefringence in the choroid and lamina cribrosa, and birefringent layered structure of the sclera. The theoretical details of the depth-localized birefringence imaging and conventional phase retardation imaging are formulated. This formulation indicates that the birefringence imaging correctly measures a depth-localized single-trip phase retardation of a tissue, while the conventional phase retardation can provide correct single-trip phase retardation only for some specific types of samples. PMID:26713208

  20. Temperature sensibility of the birefringence properties in side-hole photonic crystal fiber filled with Indium

    SciTech Connect

    Reyes-Vera, Erick Gómez-Cardona, Nelson D.; Chesini, Giancarlo; Cordeiro, Cristiano M. B.; Torres, Pedro

    2014-11-17

    We report on the temperature sensitivity of the birefringence properties of a special kind of photonic crystal fiber containing two side holes filled with Indium metal. The modulation of the fiber birefringence is accomplished through the stress field induced by the expansion of the metal. Although the fiber was made at low gas pressures during the indium infiltration process, the birefringence showed anomalous property at a relatively low temperature value, which is completely different from those reported in conventional-like fibers with two holes filled with metal. By modeling the anisotropic changes induced by the metal expansion to the refractive index within the fiber, we are able to reproduce the experimental results. Our results have practical relevance for the design of devices based on this technology.

  1. Cosmic birefringence fluctuations and cosmic microwave background B-mode polarization

    NASA Astrophysics Data System (ADS)

    Lee, Seokcheon; Liu, Guo-Chin; Ng, Kin-Wang

    2015-06-01

    Recently, BICEP2 measurements of the cosmic microwave background (CMB) B-mode polarization has indicated the presence of primordial gravitational waves at degree angular scales, inferring the tensor-to-scalar ratio of r = 0.2 and a running scalar spectral index, provided that dust contamination is low. In this Letter, we show that the existence of the fluctuations of cosmological birefringence can give rise to CMB B-mode polarization that fits BICEP2 data with r < 0.11 and no running of the scalar spectral index. When dust contribution is taken into account, we derive an upper limit on the cosmological birefringence, Aβ2 < 0.0075, where A is the amplitude of birefringence fluctuations that couple to electromagnetism with a coupling strength β.

  2. Birefringence imaging in biological tissue using polarization sensitive optical coherent tomography

    DOEpatents

    De Boer, Johannes F.; Milner, Thomas E.; Nelson, J. Stuart

    2001-01-01

    Employing a low coherence Michelson interferometer, two dimensional images of optical birefringence in turbid samples as a function of depth are measured. Polarization sensitive detection of the signal formed by interference of backscattered light from the sample and a mirror or reference plane in the reference arm which defines a reference optical path length, give the optical phase delay between light propagating along the fast and slow axes of the birefringence sample. Images showing the change in birefringence in response to irradiation of the sample are produced as an example of the detection apparatus and methodology. The technique allow rapid, noncontact investigation of tissue or sample diagnostic imaging for various medical or materials procedures.

  3. Birefringence imaging of biological tissue by spectral domain polarization sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Jing, Zhijun; Fan, Chuanmao; Jiang, Jingying; Gong, Qiang; Ma, Zhenhe; Zhang, Fan; Yao, Jianquan; Wang, R. K.

    2007-02-01

    A spectral domain Polarization sensitive optical coherence tomography (SDPS-OCT) system has been developed to acquire depth images of biological tissues such as porcine tendon, rabbit eye. The Stocks vectors (I, Q, U, and V) of the backscattered light from the biological tissues have been reconstructed. Further, the phase retardation and polarization degree between the two orthogonal polarizing states have been computed. Reconstructed images, i.e. birefringence images, from Stokes parameters, retardation and polarization degree of biological tissues show significant local variations in the polarization state. And the birefringence contrast of biological tissue possibly changes by some outside force. In addition, the local thickness of the birefringence layer determined with our system is significant. The results presented show SDPS-OCT is a potentially powerful technique to investigate tissue structural properties on the basis of the fact that any fibrous structure with biological tissues can influence the polarization state of light.

  4. A promising birefringent crystal Ba2Na3(B3O6)2F

    NASA Astrophysics Data System (ADS)

    Wang, Xing; Xia, Mingjun; Li, R. K.

    2014-12-01

    Bulk crystals of Ba2Na3(B3O6)2F (BNBF) have been successfully grown by top-seeded solution growth (TSSG) technique. Its transmittance spectra show a wide transparency range from 186 nm to 3000 nm. The refractive indices in 13 wavelengths were measured with high accuracy and the Sellmeier equations were obtained, which demonstrated that the title crystal displayed a birefringence (Δn = 0.1030 at 588 nm) comparable to that of the commercial birefringent crystal α-BBO (the high temperature form of BaB2O4). A prototype Glan-Taylor polarizer made of BNBF prisms was fabricated, which showed high transparency and large optical extinction ratio similar to the commercial polarizer made of α-BBO. In addition, BNBF crystal is less moisture sensitive than that of α-BBO, thus BNBF can be a potential new birefringent crystal.

  5. Form birefringence induced in multicomponent glass by femtosecond laser direct writing.

    PubMed

    Cao, Jing; Mazerolles, Léo; Lancry, Matthieu; Solas, Denis; Brisset, François; Poumellec, Bertrand

    2016-06-15

    We demonstrate a new kind of form birefringence in lithium niobium silicate glass induced by femtosecond laser direct writing. By combining electron backscatter diffraction and transmission electron microscopy, we reveal a self-assembled nanostructure consisting of periodic phase change: nonlinear optical nanocrystals embedded in a network of "walls" in a vitreous phase. These "walls" are aligned perpendicular to the laser polarization direction. This self-organized nanostructure may successfully explain the origin of the laser-induced birefringence in this multicomponent glass quite differently from pure silica. These findings highlight a spectacular modification of glass, and enable construction of a high contrast three-dimensional refractive index and birefringent structures at the micrometer scale in multicomponent glasses. PMID:27304277

  6. En face parametric imaging of tissue birefringence using polarization-sensitive optical coherence tomography.

    PubMed

    Chin, Lixin; Yang, Xiaojie; McLaughlin, Robert A; Noble, Peter B; Sampson, David D

    2013-06-01

    A technique for generating en face parametric images of tissue birefringence from scans acquired using a fiber-based polarization-sensitive optical coherence tomography (PS-OCT) system utilizing only a single-incident polarization state is presented. The value of birefringence is calculated for each A-scan in the PS-OCT volume using a quadrature demodulation and phase unwrapping algorithm. The algorithm additionally uses weighted spatial averaging and weighted least squares regression to account for the variation in phase accuracies due to varying OCT signal-to-noise-ratio. The utility of this technique is demonstrated using a model of thermally induced damage in porcine tendon and validated against histology. The resulting en face images of tissue birefringence are more useful than conventional PS-OCT B-scans in assessing the severity of tissue damage and in localizing the spatial extent of damage. PMID:23733021

  7. A bifunctional amorphous polymer exhibiting equal linear and circular photoinduced birefringences.

    PubMed

    Royes, Jorge; Provenzano, Clementina; Pagliusi, Pasquale; Tejedor, Rosa M; Piñol, Milagros; Oriol, Luis

    2014-11-01

    The large and reversible photoinduced linear and circular birefringences in azo-compounds are at the basis of the interest in these materials, which are potentially useful for several applications. Since the onset of the linear and circular anisotropies relies on orientational processes, which typically occur on the molecular and supramolecular length scale, respectively, a circular birefringence at least one order of magnitude lower than the linear one is usually observed. Here, the synthesis and characterization of an amorphous polymer with a dimeric repeating unit containing a cyanoazobenzene and a cyanobiphenyl moiety are reported, in which identical optical linear and circular birefringences are induced for proper light dose and ellipticity. A pump-probe technique and an analytical method based on the Stokes-Mueller formalism are used to investigate the photoinduced effects and to evaluate the anisotropies. The peculiar photoresponse of the polymer makes it a good candidate for applications in smart functional devices. PMID:25257542

  8. Novel technique for distributed fibre sensing based on coherent Rayleigh scattering measurements of birefringence

    NASA Astrophysics Data System (ADS)

    Lu, Xin; Soto, Marcelo A.; Thévenaz, Luc

    2016-05-01

    A novel distributed fibre sensing technique is described and experimentally validated, based on birefringence measurements using coherent Rayleigh scattering. It natively provides distributed measurements of temperature and strain with more than an order of magnitude higher sensitivity than Brillouin sensing, and requiring access to a single fibre-end. Unlike the traditional Rayleigh-based coherent optical time-domain reflectometry, this new method provides absolute measurements of the measurand and may lead to a robust discrimination between temperature and strain in combination with another technique. Since birefringence is purposely induced in the fibre by design, large degrees of freedom are offered to optimize and scale the sensitivity to a given quantity. The technique has been validated in 2 radically different types of birefringent fibres - elliptical-core and Panda polarization-maintaining fibres - with a good repeatability.

  9. Magnetic field fiber sensor based on the magneto-birefringence effect of magnetic fluid

    NASA Astrophysics Data System (ADS)

    Lei, Xueqin; Chen, Jiajia; Shi, Fuquan; Chen, Daru; Ren, Zhijun; Peng, Baojin

    2016-09-01

    In this study, the magneto-birefringence effect of magnetic fluid (MF) is adopted to form an innovative fiber optic magnetic field sensor. The sensitive section is fabricated via a D-shaped microstructure inscribed in a high-birefringence fiber Sagnac loop with a femtosecond laser. The D-shaped microstructure facilitates good combination of the optical-fiber Sagnac interferometer with the magneto-birefringence effect of MF without suffering from absorption loss and manual alignment. Experimental results show the good performance of the magnetic field fiver sensor, particularly its high stable extinction ratio. Preliminary results are provided, and the magnetic field sensitivity of 0.0823 nm/mT can be further improved by increasing the depth and length of the D-shaped microstructure.

  10. Influence of temperature on dynamics of birefringence switching in photochromic nematic phase

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Czajkowski, Maciej; Bartkiewicz, Stanislaw; Zygadlo, Krystian; Galewski, Zbigniew; Sahraoui, Bouchta

    2011-12-01

    We present results of dynamic and fast switching of birefringence in a photochromic liquid-crystalline system as a function of the sample temperature. The system consists of photochromic molecules of 4-heptyl-4'-methoxyazobenzene showing a liquid-crystalline nematic state close to room temperature. An experiment of dynamic birefringence switching was done in optical Kerr-effect set-up, where for the sample excitation, a picosecond-pulsed laser was used. Measurements were done for different temperatures of the sample in the liquid-crystalline nematic phase. We have proposed a mathematical model of dynamic, fast, and fully reversible birefringence changes. Theoretical estimations and experimental results have shown very good agreement.

  11. Development of a noninvasive corneal birefringence-compensated glucose-sensing polarimeter

    NASA Astrophysics Data System (ADS)

    Anumula, Harini; Nezhuvingal, Ajaina A.; Li, Yanfang; Cameron, Brent D.

    2003-07-01

    In the recent past, optical polarimetry has been shown as a potential method for noninvasive physiologic glucose sensing in the eye. Although the necessary sensitivity and accuracy have been demonstrated experimentally through in vitro studies using a range of media from simplistic glucose doped-water to more complex media such as aqueous humor, the main problem currently hindering long-term in vivo measurements is corneal birefringence coupled with motion artifact. This is due to the inability to distinguish E-field rotation due to glucose from the effects of time varying corneal birefringence. In this investigation, the effect of corneal birefringence will be discussed and a potential method to overcome this problem will be presented with supporting results.

  12. Design of Topas microstructured fiber with ultra-flattened chromatic dispersion and high birefringence

    NASA Astrophysics Data System (ADS)

    Wang, Doudou; Wang, Lili

    2011-12-01

    A microstructured polymer optical fiber (mPOF) with both ultra-flattened near-zero chromatic dispersion and high birefringence based on Topas cyclic olefin copolymer is designed. Three rings of uniform elliptical air holes are arranged in triangular lattice in the cladding and an extra small defected hole is introduced in the fiber core. Guided modes, dispersion, birefringence and mode confinement properties of the designed mPOF are investigated by using the full-vector finite element method. Dispersion values between ± 0.5 ps/km/nm over the wavelength 1.1-1.7 μm and high birefringence of the order of 10 -3 are obtained for the optimized fiber structure. Low confinement losses and small effective mode area are obtained at the same time. The relatively simple architecture of the proposed Topas mPOF can be fabricated by our extrusion-stretching techniques.

  13. High average power pulsed phase conjugate laser with birefringence correction. Revision 1

    SciTech Connect

    Bowers, M.W.; Hankla, A.K.; Jacobson, G.F.

    1994-05-01

    Nd:YAG rod lasers have been plagued with the inability to go to high average powers because of thermally induced birefringence and focusing. Several methods have been employed to correct for the birefringence and the thermal aberrations of such systems, but place stringent constraints on the laser heads and/or the system alignment. They have developed a scalable Nd: YAG master oscillator/power amplifier (MOPA) laser system which employs a novel phase conjugation scheme to correct both for the material and thermal distortions as well as the thermal birefringence in double pass amplifier systems. This method reduces the double pass depolarization from 42% to less than 2% and is easy to align.

  14. Effect of dimerization on the field-induced birefringence in ferrofluids.

    PubMed

    Szczytko, Jacek; Vaupotič, Nataša; Osipov, Mihail A; Madrak, Karolina; Górecka, Ewa

    2013-06-01

    The magnetic-field-induced birefringence in a ferrofluid composed of spherical cobalt nanoparticles has been studied both experimentally and theoretically. The considerable induced birefringence determined experimentally has been attributed to the formation of chains of nanoparticles. The birefringence has been measured as a function of the external magnetic field and the volume fraction (f) of nanoparticles. It is quadratic in f as opposed to the Faraday effect, which is linear in f. Experimental results agree well with the theoretical model based on a simple density functional approach. For dilute solutions the experimental results can be explained by assuming that only dimers of nanoparticles are formed while the concentration of longer chains is negligible. PMID:23848690

  15. Design and analysis of surface plasmon resonance sensor based on high-birefringent microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Nancy Meng Ying; Juan Juan Hu, Dora; Shum, Perry Ping; Wu, Zhifang; Li, Kaiwei; Huang, Tianye; Wei, Lei

    2016-06-01

    Optical fiber based surface plasmon resonance (SPR) sensors are favored by their high sensitivity, compactness, remote and in situ sensing capabilities. Microstructured optical fibers (MOFs) possess microfluidic channels extended along the entire length right next to the fiber core, thereby enabling the infiltrated biochemical analyte to access the evanescent field of guided light. Since SPR can only be excited by the polarization vertical to metal surface, external perturbation could induce the polarization crosstalk in fiber core, thus leading to the instability of sensor output. Therefore for the first time we analyze how the large birefringence suppresses the impact of polarization crosstalk. We propose a high-birefringent MOF based SPR sensor with birefringence larger than 4 × 10‑4 as well as easy infiltration of microfluidic analyte, while maintaining sensitivity as high as 3100 nm/RIU.

  16. Collinear mixing of orthogonally polarized waves via polarization hole burning in birefringent Er-doped fiber

    NASA Astrophysics Data System (ADS)

    Stepanov, S.; Hernández, E.; Plata, M.

    2005-01-01

    We report on experimental observation of transient mixing of two mutually coherent waves of orthogonal polarizations collinearly propagating through birefringent Er-doped fiber. The dynamic grating responsible for this two-wave mixing (TWM) process is formed via effect of polarization hole burning (PHB) and has spatial period equal to the beat length of the fiber birefringence. Experiments were performed at the laser wavelength 1549 nm in 2-m long Er-doped fiber with 2-cm birefringence beat length without optical pumping. We observed that the transient collinear TWM has amplitude and characteristic relaxation time close to those of transient PHB effect measured for linearly polarized light and similar to corresponding characteristics of transient TWM observed for counter-propagating orthogonally polarized waves in the same fiber.

  17. Probing vacuum birefringence using x-ray free electron and optical high-intensity lasers

    NASA Astrophysics Data System (ADS)

    Karbstein, Felix; Sundqvist, Chantal

    2016-07-01

    Vacuum birefringence is one of the most striking predictions of strong field quantum electrodynamics: Probe photons traversing a strong field region can indirectly sense the applied "pump" electromagnetic field via quantum fluctuations of virtual charged particles which couple to both pump and probe fields. This coupling is sensitive to the field alignment and can effectively result in two different indices of refraction for the probe photon polarization modes giving rise to a birefringence phenomenon. In this article, we perform a dedicated theoretical analysis of the proposed discovery experiment of vacuum birefringence at an x-ray free electron laser/optical high-intensity laser facility. Describing both pump and probe laser pulses realistically in terms of their macroscopic electromagnetic fields, we go beyond previous analyses by accounting for various effects not considered before in this context. Our study facilitates stringent quantitative predictions and optimizations of the signal in an actual experiment.

  18. Binding of biological effectors on magnetic nanoparticles measured by a magnetically induced transient birefringence experiment

    NASA Astrophysics Data System (ADS)

    Wilhelm, C.; Gazeau, F.; Roger, J.; Pons, J. N.; Salis, M. F.; Perzynski, R.; Bacri, J. C.

    2002-03-01

    We have investigated the relaxation of the magnetically induced birefringence in a suspension of magnetic nanoparticles in order to detect the binding reaction of polyclonal antibodies on the particle surface. The birefringence relaxation is driven by the rotational diffusion of the complex formed by the magnetic nanoparticles bound to the antibody and thus is directly related to the hydrodynamic size of this complex. Birefringence relaxations are well described by stretched exponential laws revealing a polydisperse distribution of hydrodynamic diameters. Comparing the size distribution of samples with different initial ratios of immunoglobuline added per magnetic nanoparticles, we evidence the graft of an antibody on particle and eventually the onset of particles agregation. Measurements on samples separated in size by gel filtration demonstrate the robustness of our experiment for the determination of size distribution and its modification due to the adsorption of a macromolecule. The immunoglobuline binding assay is performed comparatively for ionic magnetic nanoparticles with different coatings.

  19. En face parametric imaging of tissue birefringence using polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Chin, Lixin; Yang, Xiaojie; McLaughlin, Robert A.; Noble, Peter B.; Sampson, David D.

    2013-06-01

    A technique for generating en face parametric images of tissue birefringence from scans acquired using a fiber-based polarization-sensitive optical coherence tomography (PS-OCT) system utilizing only a single-incident polarization state is presented. The value of birefringence is calculated for each A-scan in the PS-OCT volume using a quadrature demodulation and phase unwrapping algorithm. The algorithm additionally uses weighted spatial averaging and weighted least squares regression to account for the variation in phase accuracies due to varying OCT signal-to-noise-ratio. The utility of this technique is demonstrated using a model of thermally induced damage in porcine tendon and validated against histology. The resulting en face images of tissue birefringence are more useful than conventional PS-OCT B-scans in assessing the severity of tissue damage and in localizing the spatial extent of damage.

  20. Determination of the refractive index difference caused by the birefringence of FA (II) centers in KCl:Li

    NASA Astrophysics Data System (ADS)

    Silfsten, Pertti; Ketolainen, Pertti

    1991-11-01

    A method is described for determining the refractive index difference caused by the birefringence of oriented FA (II) centers in KCl:Li crystals. It is shown that the portion induced by the birefringence can be separated from an absorption spectrum measured through a polarizer-analyzer system. From this portion the refractive index difference can then be calculated with ease.

  1. Flow-induced birefringence: the hidden PSF killer in high performance injection-molded plastic optics

    NASA Astrophysics Data System (ADS)

    Chidley, Matthew D.; Tkaczyk, Tomasz; Kester, Robert; Descour, Michael R.

    2006-02-01

    A 7-mm OD, NA = 1 water immersion injection-molded plastic endoscope objective has been fabricated for a laser scanning fiber confocal reflectance microscope (FCRM) system specifically designed for in vivo detection of cervical and oral pre-cancers. Injection-molded optics was selected for the ability to incorporate aspheric surfaces into the optical design and its high volume capabilities. Our goal is high performance disposable endoscope probes. This objective has been built and tested as a stand-alone optical system, a Strehl ratio greater than 0.6 has been obtained. One of the limiting factors of optical performance is believed to be flow-induced birefringence. We have investigated different configurations for birefringence visualization and believe the circular polariscope is most useful for inspection of injection-molded plastic optics. In an effort to decrease birefringence effects, two experiments were conducted. They included: (1) annealing of the optics after fabrication and (2) modifying the injection molding prameters (packing pressures, injection rates, and hold time). While the second technique showed improvement, the annealing process could not improve quality without physically warping the lenses. Therefore, to effectively reduce flow-induced birefringence, molding conditions have to be carefully selected. These parameters are strongly connected to the physical part geometry. Both optical design and fabrication technology have to be considered together to deliver low birefringence while maintaining the required manufacturing tolerances. In this paper we present some of our current results that illustrate how flow-induced birefringence can degrade high performance injection-molded plastic optical systems.

  2. Supramolecular assembly of bis(benzimidazole)pyridine: an extended anisotropic ligand for highly birefringent materials.

    PubMed

    Thompson, John R; Ovens, Jeffrey S; Williams, Vance E; Leznoff, Daniel B

    2013-12-01

    Four new bis(benzimidazole)pyridine (BBP)-containing compounds Zn(BBP)Cl[Au(CN)2], Mn(BBP)[Au(CN)2]2·H2O, Mn(BBP)Br2(MeOH) and Mn(BBP)Cl2(MeOH)·MeOH have been synthesized and structurally characterized and their birefringence values (Δn) determined. The structure of Zn(BBP)Cl[Au(CN)2] contains a hydrogen-bonded dimer of Zn(BBP)Cl[Au(CN)2] units which propagate into a 1D chain through Au-Au interactions, although the crystals are of poor optical quality. The supramolecular structure of Mn(BBP)[Au(CN)2]2·H2 O forms a 1D coordination polymer through chains of Mn(BBP)[Au(CN)2]2 units, each containing one bridging Au(CN)2 and one forming a 2D sheet through Au-Au interactions. The supramolecular structures of Mn(BBP)Br2(MeOH) and Mn(BBP)Cl2(MeOH)·MeOH are very similar, consisting of a complex hydrogen-bonded network between NH imidazole, methanol and halide groups to align BBP building blocks. In the plane of the primary crystal growth direction, the birefringence values of the three Mn-containing materials were Δn=0.08(1), 0.538(3) and 0.69(3), respectively. The latter two birefringence values are larger than in the related 2,2';6'2''-terpyridine systems, placing them among the most birefringent solids reported. These compounds illustrate the utility of extending the π-system of the building block and incorporating hydrogen-bonding sites as design elements for highly birefringent materials and also illustrates the effect on the measurable birefringence of the crystal quality, growth direction and structural alignment of the anisotropic BBP building blocks. PMID:24281807

  3. Temperature dependence of birefringence in ethanol-filled suspended core fiber.

    PubMed

    Vilas, Jose Luis; Sanchez-Martin, Jose Antonio; Bernabeu, Eusebio

    2016-08-10

    The temperature dependence of the birefringence in a suspended core fiber (SCF) has been experimentally analyzed by using a polarimetric setup. The used configuration consists of two linear polarizers and the SCF as birefringent medium. A theoretical study based on Jones matrices has been carried out to analyze the experimental observed behavior. For this, a polarimetric all-fiber configuration was used whose sensitivity depends on the wavelength variation with temperature. Results obtained show that it is strongly affected when the air holes of SCF are partially filled with ethanol. PMID:27534462

  4. Orientational order of some liquid crystal/dye mixtures obtained from optical birefringence

    NASA Astrophysics Data System (ADS)

    Bielejewska, Natalia

    2016-04-01

    This study presents optical birefringence measurements as a function of temperature for the liquid crystal/dye mixtures. The optical birefringence of the liquid crystals used in liquid crystal displays technology is related to the order parameter , which is crucial from the development point of view. The properties of the dyes (4-dimethylamino-4‧-nitrostilbene and N,N‧-bis(2,5-di-tert-buthylphenyl)-3,4,9,10-perylenedicarboximide) as a guest molecule are tested over the whole region of nematic phase occurrence by three different methods: measurement with use of the plano-convex lens, Berek's compensator and photoelastic modulator.

  5. The effect of vacuum birefringence on the polarization of X-ray binaries and pulsars

    NASA Technical Reports Server (NTRS)

    Novick, R.; Weisskopf, M. C.; Angel, J. R. P.; Sutherland, P. G.

    1977-01-01

    In a strong magnetic field the vacuum becomes birefringent. This effect is especially important for pulsars at X-ray wavelengths. Any polarized X-ray emission from the surface of a magnetic neutron star becomes depolarized as it propagates through the magnetic field. The soft X-ray emission from AM Her, believed to be a magnetic white dwarf, may show about one radian of phase retardation. In this case, circular polarization of the X-ray flux would be a characteristic signature of vacuum birefringence.

  6. Single layer retarder with negative dispersion of birefringence and wide field-of-view.

    PubMed

    Hwang, Jiyong; Yang, Seungbin; Choi, Yu-Jin; Lee, Yumin; Jeong, Kwang-Un; Lee, Ji-Hoon

    2016-08-22

    A single layer retarder possessing negative dispersion (ND) of birefringence as well as wide field-of-view (FOV) was long-term objective in optical science. We synthesized new guest reactive monomers with x-shape and mixed them with the host smectic reactive mesogen. The host-guest molecules formed two dimensionally self-organized nanostructure and showed both the ND of birefringence and wide FOV properties. We simulated the antireflection property of a circular polarizer using the optical properties of the retarder. The average reflectance of the retarder was 0.52% which was much smaller than that of the commercial single layer ND retarder 1.83%. PMID:27557268

  7. Birefringence lens effects of an atom ensemble enhanced by an electromagnetically induced transparency

    SciTech Connect

    Zhang, H. R.; Sun, C. P.; Zhou Lan

    2009-07-15

    We study the optical control for birefringence of a polarized light by an atomic ensemble with a tripod configuration, which is mediated by the electromagnetically induced transparency with a spatially inhomogeneous laser. The atomic ensemble splits the linearly polarized light ray into two orthogonally polarized components, whose polarizations depend on quantum superposition of the initial states of the atomic ensemble. Accompanied with this splitting, the atomic ensemble behaves as a birefringent lens, which allows one polarized light ray passing through straightly while focuses the other light of vertical polarization with finite aberration of focus.

  8. Dark three-sister rogue waves in normally dispersive optical fibers with random birefringence.

    PubMed

    Chen, Shihua; Soto-Crespo, Jose M; Grelu, Philippe

    2014-11-01

    We investigate dark rogue wave dynamics in normally dispersive birefringent optical fibers, based on the exact rational solutions of the coupled nonlinear Schrödinger equations. Analytical solutions are derived up to the second order via a nonrecursive Darboux transformation method. Vector dark "three-sister" rogue waves as well as their existence conditions are demonstrated. The robustness against small perturbations is numerically confirmed in spite of the onset of modulational instability, offering the possibility to observe such extreme events in normal optical fibers with random birefringence, or in other Manakov-type vector nonlinear media. PMID:25401907

  9. Pulsed laser induced switching of birefringence in nematic phase of photochromic molecules

    NASA Astrophysics Data System (ADS)

    Mysliwiec, J.; Czajkowski, M.; Bartkiewicz, S.; Zygadlo, K.; Galewski, Z.; Sahraoui, B.

    2011-02-01

    Fast and dynamic switching of liquid-crystalline photochromic system birefringence induced by pulsed laser has been observed. The system consisted of photochromic molecules of 4-heptyl-4'-methoxyazobenzene showing liquid-crystalline nematic state close to the room temperature. Experiment of dynamic birefringence switching was done in optical Kerr effect (OKE) set-up, where for the sample excitation picosecond pulsed laser was used. Simultaneously, HeNe laser was served as a probe beam source. Measurements were done for different voltages applied to the sample. Rise time constant was in the range of microseconds. Full reversibility of the OKE signal was observed.

  10. Modeling the rabbit's eye with the Mueller matrix for birefringent properties

    NASA Astrophysics Data System (ADS)

    Baba, Justin S.; Cooper, Califf T.; Cote, Gerard L.

    2003-07-01

    The effect of changing corneal birefringence, due to motion artifact, remains a major obstacle to the development of an accurate non-invasive polarimetric glucose sensor for patients with diabetes mellitus. Consequently, there is still a need to characterize fully, and to quantify the relative changes in corneal birefringence to facilitate the optimization of detection algorithms, enabling in vivo accuracy within 10mg/dl. In this paper, we present preliminary results, utilizing a Mueller matrix imaging technique, that demonstrates notable relative changes in the apparent retardance and in the apparent fast axis location of rabbit cornea.

  11. Wide-spectrum reconstruction method for a birefringence interference imaging spectrometer.

    PubMed

    Zhang, Chunmin; Jian, Xiaohua

    2010-02-01

    We present a mathematical method used to determine the spectrum detected by a birefringence interference imaging spectrometer (BIIS). The reconstructed spectrum has good precision over a wide spectral range, 0.4-1.0 microm. This method considers the light intensity as a function of wavelength and avoids the fatal error caused by birefringence effect in the conventional Fourier transform method. The experimental interferogram of the BIIS is processed in this new way, and the interference data and reconstructed spectrum are in good agreement, proving this method to be very exact and useful. Application of this method will greatly improve the instrument performance. PMID:20125723

  12. Integrated optic polarization splitter based on total internal reflection from a birefringent polymer.

    PubMed

    Huang, Guanghao; Park, Tae-Hyun; Chu, Woo-Sung; Oh, Min-Cheol

    2016-09-01

    An integrated optic polarization splitter with large fabrication tolerance and high reliability is required for optical signal processing in quantum-encrypted communication systems. A polarization splitter based on total internal reflection from a highly birefringent polymer-reactive mesogen-is proposed and demonstrated in this work. The device consists of a mode expander for reducing the wave vector distribution of the guided mode, and an interface with a large birefringence. Several polymers with suitable refractive indexes were used for fabricating the device. We obtained a polarization splitter with a low crosstalk (less than -30 dB), and a large fabrication tolerance. PMID:27607704

  13. Method and apparatus for measuring micro structures, anisotropy and birefringence in polymers using laser scattered light

    DOEpatents

    Grek, Boris; Bartolick, Joseph; Kennedy, Alan D.

    2000-01-01

    A method and apparatus for measuring microstructures, anistropy and birefringence in polymers using laser scattered light includes a laser which provides a beam that can be conditioned and is directed at a fiber or film which causes the beam to scatter. Backscatter light is received and processed with detectors and beam splitters to obtain data. The data is directed to a computer where it is processed to obtain information about the fiber or film, such as the birefringence and diameter. This information provides a basis for modifications to the production process to enhance the process.

  14. Investigation of optical and thermal properties of N-(alkyl-substituted) maleimides for use in zero-zero-birefringence polymer.

    PubMed

    Beppu, Shotaro; Hotta, Hikaru; Shafiee, Houran; Tagaya, Akihiro; Koike, Yasuhiro

    2015-02-01

    N-(alkyl-substituted) maleimides (RMIs) were proposed as materials useful for the development of a zero-zero-birefringence polymer that exhibits no birefringence. We analyzed the optical and thermal properties of poly(RMI)s, such as the refractive index, birefringence, and glass transition temperature. The characteristics of the obtained polymers varied significantly because the shift of the density and polarizability derived from the change of the substituent structure influenced the optical properties, and the bulkiness of the substituents influenced the thermal properties. We also designed a zero-zero-birefringence polymer using N-ethyl maleimide (EMI) as a comonomer, and the obtained copolymer had no birefringence, relatively high heat resistance, and high transparency. PMID:25967788

  15. Origin of birefringence in andradite from Arizona, Madagascar, and Iran

    NASA Astrophysics Data System (ADS)

    Antao, Sytle M.; Klincker, Allison M.

    2013-07-01

    The crystal structure of four birefringent andradite samples (two from Arizona, one from Madagascar, and one from Iran) was refined with the Rietveld method, space group Iaoverline{3} d, and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Each sample contains an assemblage of three different cubic phases. From the electron-microprobe (EMPA) results, fine-scale intergrowths in the Arizona-2 and Madagascar samples appear homogeneous with nearly identical compositions of {Ca2.99Mg0.01}Σ3[{{Fe}}_{1.99}^{3 + } {{Mn}}_{0.01}^{3 + }]Σ2(Si2.95Al0.03 {{Fe}}_{0.02}^{3 + })Σ3O12, Adr98 (Arizona-2), and Adr97 (Madagascar). Both samples are near-end-member andradite, ideally {Ca3}[{{Fe}}2^{3 + }](Si3)O12, so cation ordering in the X, Y, or Z sites is not possible. Because of the large-scale intergrowths, the Arizona-1 and Iran samples contain three different compositions. Arizona-1 has compositions Adr97 (phase-1), Adr93Grs4 (phase-2), and Adr87Grs11 (phase-3). Iran sample has compositions Adr86Uv12 (phase-1), Adr69Uv30 (phase-2), and Adr76Uv22 (phase-3). The crystal structure of the three phases within each sample was modeled quite well as indicated by the Rietveld refinement statistics of reduced χ2 and overall R ( F 2) values of, respectively, 1.980 and 0.0291 (Arizona-1); 1.091 and 0.0305 (Arizona-2); 1.362 and 0.0231 (Madagascar); and 1.681 and 0.0304 (Iran). The dominant phase for each sample has the following unit-cell parameters (Å) and weight fractions (%): a = 12.06314(1), 51.93(9) (Arizona-1); 12.04889(1), 52.47(1) (Arizona-2); 12.06276(1), 52.21(8) (Madagascar); and 12.05962(2), 63.3(1) (Iran). For these dominant phases, the distances and site occupancy factors ( sofs) in terms of neutral atoms at the Ca(X), Fe(Y), and Si(Z) sites are as follows: = 2.4348, Fe-O = 2.0121(6), Si-O = 1.6508(6) Å; Ca( sof) = 0.955(2), Fe( sof) = 0.930(2), and Si( sof) = 0.917(2) (Arizona-1); = 2.4288, Fe-O = 2.0148(7), Si-O = 1

  16. Polarization-insensitive all-optical dual pump-phase transmultiplexing from 2 × 10-GBd OOKs to 10-GBd RZ-QPSK using cross-phase modulation in a birefringent nonlinear PCF.

    PubMed

    Mahmood, T; Cannon, B M; Astar, W; Carter, G M

    2014-12-29

    Polarization-insensitive (PI) all-optical dual pump-phase transmultiplexing from 2 × 10-GBd OOKs to 10-GBd RZ-QPSK was successfully demonstrated in a birefringent nonlinear photonic crystal fiber (PCF), by utilizing cross-phase modulation (XPM) and the inherent birefringence of the device, for the first time. PI operation was achieved by launching the probe and one pump off-axis while the state of polarization (SOP) of the other pump was randomized. Optimum pump-probe detuning, all within the C-Band, was also utilized to reduce the polarization-induced power fluctuation. Receiver sensitivity penalty at 10-9 bit-error-rate was < 5.5 dB in PI operation, relative to the FPGA-precoded RZ-DQPSK baseline. PMID:25607146

  17. Elucidating the temporal dynamics of optical birefringence changes in crustacean nerves.

    PubMed

    Badreddine, Ali H; Schoener, Kurt J; Bigio, Irving J

    2015-10-01

    Intrinsic optical properties, such as optical birefringence, may serve as a tool for minimally invasive neuroimaging methods with high spatiotemporal resolution to aid in the study of neuronal activation patterns. To facilitate imaging neuronal activity by sensing dynamic birefringence, temporal characteristics behind the signal must be better understood. We have developed a novel nerve chamber to investigate changes in birefringence at the stimulation site, and at distances ~4-28 mm from that site. Using crustacean nerves with either heterogeneous or homogeneous size distributions of axon diameters, we found that the gradual (slow) recovery of the crossed-polarized signal is not explained by the arrival times of action potentials in smaller axons. Through studying the effects of stimulating current and voltage pulses, we hypothesize that the recovery may be caused by a capacitive-like coupling between firing axons and adjacent tissue structures, and we report data consistent with this hypothesis. This study will aid in the utilization of action-potential-related changes in birefringence to study fast changes in neuronal network activity. PMID:26504663

  18. Estimation of the Intrinsic Birefringence of the A, B and V Crystalline Forms of Amylose

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optical birefringence (Delta n) for A, B, Va, Vh amylose crystals were calculated by vector summation of bond polarizabilities. Orientation of the O-H bond vectors in these amylose crystals is not well understood so results are given for likely O-H conformers. For B amylose, Delta n ranges from 0....

  19. Dynamics of laser-induced radial birefringence in silver-doped glasses.

    PubMed

    Ahangary, Ali Akbar; Bouchard, Frédéric; Santamato, Enrico; Karimi, Ebrahim; Khalesifard, Hamid Reza

    2015-09-01

    Silver ion-exchanged glass exhibits nonlinear optical properties upon interacting with intense light beams. The thermal effect due to the nanoparticles' light-absorption induces radial stress, and consequently, a radial birefringence on the glass surface. The induced birefringence possesses a topological charge of 1 in the transverse plane of the glass, i.e., cylindrical symmetry. Therefore, when the glass is illuminated with a circularly polarized light beam, a portion of the incoming beam flips its polarization handedness, since the plate is birefringent, and gains an orbital angular momentum of ±2 in units of the Planck constant. This is referred to as optical spin-to-orbital angular momentum conversion, and can be understood by means of the Pancharatnam-Berry phase. Here, we design a pump-probe setup to study and observe the dynamics of optical angular momentum coupling in real time. We show that this effect can be permanent or reversible, depending on the power and interaction time of the pump beam. In particular, an intrinsic power-dependent birefringence hysteresis is observed on the sample after interaction with and the relaxation of the irradiated point. PMID:26368712

  20. A novel high-birefringence fiber loop mirror electric current sensor

    NASA Astrophysics Data System (ADS)

    Bo, Dong; Zhao, Qida; Liao, Liubo Tongqing; Li, Shuhong; Zeng, Xiangye; Miao, Yinping; Huang, Guiling

    2007-11-01

    A novel electric current sensor based on a high-birefringence fiber loop mirror(HBFLM) and a kind of magnetostrictive material rod(MMR) is demonstrated theoretically and experimentally. Part of the high-birefringence fiber(HBF) is pasted onto the MMR which is placed in the central part of a solenoid. The HBFLM is used as the sensor head and the linear filter simultaneously. Part of the high-birefringence fiber(HBF) is pasted onto the MMR which is placed in the central part of a solenoid. The rod will have elastic lengthening along the direction of the magnetic field when the uniform magnetic field changes, which will lead to a change of transmission intensity of the HBFLM filter, thus the variation of the electric current can be determined via the laser wavelength within the quasi-linear transmission range of the HBFLM filter. The sensitivity reaches 0.0153/100mA, the resolution reaches 10mA. Comparing with the previous fiber-optic electric current sensor, it has nothing with the linear birefringence based on Faraday effects in the previous fiber-optic electric current sensor. Comparing with the expensive and complex FBG electric current, the sensing signal can be directly detected by a photodiode(PD) and complicated demodulation devices are avoidable. The advantages of the electric current include optical power detection, simple and smart structure, high sensitivity, low cost, and good repeatability, etc.

  1. Precision Interferometric Measurements of Mirror Birefringence in High-Finesse Optical Resonators

    PubMed Central

    Fleisher, Adam J.; Long, David A.; Liu, Qingnan; Hodges, Joseph T.

    2016-01-01

    High-finesse optical resonators found in ultrasensitive laser spectrometers utilize supermirrors ideally consisting of isotropic high-reflectivity coatings. Strictly speaking, however, the optical coatings are often non-uniformly stressed during the deposition process and therefore do possess some small amount of birefringence. When physically mounted the cavity mirrors can be additionally stressed in such a way that large optical birefringence is induced. Here we report a direct measurement of optical birefringence in a two-mirror Fabry-Pérot cavity with R = 99.99 % by observing TEM00 mode beating during cavity decays. Experiments were performed at a wavelength of 4.53 μm, with precision limited by both quantum and technical noise sources. We report a splitting of δν = 618(1) Hz, significantly less than the intrinsic cavity linewidth of δcav ≈ 3 kHz. With a cavity free spectral range of 96.9 MHz, the equivalent fractional change in mirror refractive index due to birefringence is therefore Δn/n = 6.38(1) × 10−6. PMID:27088133

  2. Advancement in polarimetric glucose sensing: simulation and measurement of birefringence properties of cornea

    NASA Astrophysics Data System (ADS)

    Malik, Bilal H.; Coté, Gerard L.

    2011-03-01

    Clinical guidelines dictate that frequent blood glucose monitoring in diabetic patients is critical towards proper management of the disease. Although, several different types of glucose monitors are now commercially available, most of these devices are invasive, thereby adversely affecting patient compliance. To this end, optical polarimetric glucose sensing through the eye has been proposed as a potential noninvasive means to aid in the control of diabetes. Arguably, the most critical and limiting factor towards successful application of such a technique is the time varying corneal birefringence due to eye motion artifact. We present a spatially variant uniaxial eye model to serve as a tool towards better understanding of the cornea's birefringence properties. The simulations show that index-unmatched coupling of light is spatially limited to a smaller range when compared to the index-matched situation. Polarimetric measurements on rabbits' eyes indicate relative agreement between the modeled and experimental values of corneal birefringence. In addition, the observed rotation in the plane of polarized light for multiple wavelengths demonstrates the potential for using a dual-wavelength polarimetric approach to overcome the noise due to timevarying corneal birefringence. These results will ultimately aid us in the development of an appropriate eye coupling mechanism for in vivo polarimetric glucose measurements.

  3. Polarization modulational instability in a birefringent optical fiber with fourth order dispersion

    NASA Astrophysics Data System (ADS)

    Ganapathy, R.; Kuriakose, V. C.

    2001-10-01

    We obtain conditions for the occurrence of polarization modulational instability in the anomalous and normal dispersion regimes for the coupled nonlinear Schrödinger equation modelling fourth order dispersion effects when the linearly polarized pump is oriented at arbitrary angles with respect to the slow and fast axes of the birefringent fiber.

  4. The Interplay between Viscoelastic and Thermodynamic Properties Determines the Birefringence of F-Actin Gels

    PubMed Central

    Helfer, Emmanuèle; Panine, Pierre; Carlier, Marie-France; Davidson, Patrick

    2005-01-01

    F-actin gels of increasing concentrations (25–300 μM) display in vitro a progressive onset of birefringence due to orientational ordering of actin filaments. At F-actin concentrations <100 μM, this birefringence can be erased and restored at will by sonication and gentle flow, respectively. Hence, the orientational ordering does not result from a thermodynamic transition to a nematic phase but instead is due to mechanical stresses stored in the gels. In contrast, at F-actin concentrations ≥100 μM, gels display spontaneous birefringence recovery, at rest, which is the sign of true nematic ordering, in good agreement with statistical physics models of the isotropic/nematic transition. Well-aligned samples of F-actin gels could be produced and their small-angle x-ray scattering patterns are quite anisotropic. These patterns show no sign of filament positional short-range order and could be modeled by averaging the form factor with the Maier-Saupe nematic distribution function. The derived nematic order parameter S of the gels ranged from S = 0.7 at 300 μM to S = 0.4 at 25 μM. Both birefringence and small-angle x-ray scattering data indicate that, even in absence of cross-linking proteins, spontaneous cooperative alignment of actin filaments may arise in motile regions of living cells where F-actin concentrations can reach values of a few 100 μM. PMID:15863487

  5. Polarization dependence of the strain sensitivity of fiber Bragg gratings inscribed in highly birefringent optical fibers

    NASA Astrophysics Data System (ADS)

    Singh, Paul; Jülich, Florian; Roths, Johannes

    2012-04-01

    It can be expected that the range of applications for FBG-based strain and temperature sensors would expand if the accuracy of this sensor technique was improved. In this study, polarization effects of FBG sensors, which contribute significantly to the measurement uncertainty of this technique, were investigated. Therefore, FBGs were inscribed into highly birefringent optical fibers. These sensor elements were attached to a specimen with defined orientations of the fiber's slow and fast axes with regard the specimen's surface. We observed a change of the fiber's birefringence in the order of 5 10-5 as a consequence of the gluing process, that was employed to attach the fiber onto the specimen. The strain sensitivities were determined for each polarization mode and for different fiber orientations using a highly accurate strain calibration facility. It was found that in all experiments the strain sensitivity for the slow axis was significantly higher (about 0.8%) than for the fast axis. The strain sensitivity also depends on the orientation of the fiber's birefringent axes with regard to the surface of the specimen. Although the investigations were performed with FBGs inscribed into birefringent fibers, the findings are still of importance for understanding the polarization-dependant accuracy limits of FBGs in standard single-mode fibers.

  6. Elucidating the temporal dynamics of optical birefringence changes in crustacean nerves

    PubMed Central

    Badreddine, Ali H.; Schoener, Kurt J.; Bigio, Irving J.

    2015-01-01

    Intrinsic optical properties, such as optical birefringence, may serve as a tool for minimally invasive neuroimaging methods with high spatiotemporal resolution to aid in the study of neuronal activation patterns. To facilitate imaging neuronal activity by sensing dynamic birefringence, temporal characteristics behind the signal must be better understood. We have developed a novel nerve chamber to investigate changes in birefringence at the stimulation site, and at distances ~4-28 mm from that site. Using crustacean nerves with either heterogeneous or homogeneous size distributions of axon diameters, we found that the gradual (slow) recovery of the crossed-polarized signal is not explained by the arrival times of action potentials in smaller axons. Through studying the effects of stimulating current and voltage pulses, we hypothesize that the recovery may be caused by a capacitive-like coupling between firing axons and adjacent tissue structures, and we report data consistent with this hypothesis. This study will aid in the utilization of action-potential-related changes in birefringence to study fast changes in neuronal network activity. PMID:26504663

  7. Laser diagnostics of anisotropy in birefringent networks of biological tissues in different physiological conditions

    SciTech Connect

    Ushenko, Yu A; Tomka, Yu Ya; Dubolazov, A V

    2011-02-28

    We study the possibility of differentiation of optical anisotropy properties of biological tissues in different physiological conditions by means of statistical analysis of coordinate distributions of a new analytic parameter, namely, the complex degree of mutual anisotropy of extracellular matrix, formed by a network of birefringent filament-like protein crystals. (laser biology)

  8. High-repetition-rate oscillators based on athermal glass rods and on birefringence correction techniques

    NASA Astrophysics Data System (ADS)

    Jackel, Steven M.; Kaufman, Alon; Lallouz, Raphael

    1994-09-01

    A high-repetition-rate oscillator, based on a flashlamp-pumped Q-100- clad athermal phosphate glass rod in a stable cavity, was developed to act as the driver for a high-repetition-rate Nd:glass laser system. Although the athermal properties compensated to a large extent for thermal lensing, birefringence losses in a conventional linear cavity containing a polarizer, as required for Q-switched operation, reduced pulse energy by up to a factor of 3 when the repetition rate was increased from single shot to 50% of fracture-limit pump conditions. Several birefringence compensation techniques were evaluated with the best results obtained in a reentrant (Y-cavity) design, with a Faraday rotator to partially compensate for birefringence and a mirror to reinsert polarizer-rejected light, so that the light quadruple passed the laser head per cavity round-trip and egressed through the output mirror (the only oscillator exit port). Birefringence losses were then reduced to 20%. High-repetition-rate TEM 00 operation was obtained by using a long (223-cm) cavity, and by placing the Faraday rotator/laser head together with a large mode selection aperture next to the curved back mirror.

  9. Precision interferometric measurements of mirror birefringence in high-finesse optical resonators

    NASA Astrophysics Data System (ADS)

    Fleisher, Adam J.; Long, David A.; Liu, Qingnan; Hodges, Joseph T.

    2016-01-01

    High-finesse optical resonators found in ultrasensitive laser spectrometers utilize supermirrors ideally consisting of isotropic high-reflectivity coatings. Strictly speaking, however, the optical coatings are often nonuniformly stressed during the deposition process and therefore do possess some small amount of birefringence. When physically mounted the cavity mirrors can be additionally stressed in such a way that large optical birefringence is induced. Here we report a direct measurement of optical birefringence in a two-mirror Fabry-Pérot cavity with R =99.99 % by observing TEM00 mode beating during cavity decays. Experiments were performed at a wavelength of 4.53 μ m , with precision limited by both quantum and technical noise sources. We report a splitting of δν=618 (1 ) Hz, significantly less than the intrinsic cavity line width of δcav≈3 kHz. With a cavity free spectral range of 96.9 MHz, the equivalent fractional change in mirror refractive index due to birefringence is therefore Δ n /n =6.38 (1 ) ×10-6 .

  10. Critical behavior of a nonpolar smectogen from high-resolution birefringence measurements

    NASA Astrophysics Data System (ADS)

    Erkan, Selen; Çetinkaya, Mehmetcan; Yildiz, Sevtap; Özbek, Haluk

    2012-10-01

    We report high-sensitivity and high-temperature resolution experimental data for the temperature dependence of the optical birefringence of a nonpolar monolayer smectogen 4-butyloxyphenyl-4'-decyloxybenzoate (10¯.O.4¯) liquid crystal by using a rotating-analyzer technique. The birefringence data cover nematic and smectic-A phases of the 10¯.O.4¯ compound. The birefringence data are used to probe the temperature behavior of the nematic order parameter S(T) in the vicinity of both the nematic-isotropic (N-I) and the nematic-smectic-A (N-SmA) transitions. For the N-I transition, from the data sufficiently far away from the smectic-A phase, the average value of the critical exponent β describing the limiting behavior of S(T) is found to be 0.2507±0.0010, which is in accordance with the so-called tricritical hypothesis, which predicts β=0.25 and excludes higher theoretical values. The critical behavior of S(T) at the N-I transition is discussed in detail by comparing our results with the latest reports in the literature and we conclude that by comparing with the previously reported results, the isotropic internal field assumption by the Vuks-Chandrasekhar-Madhusudana model is adequate to extract the critical behavior of S(T) from the optical birefringence data. We observe that there is no discontinuous behavior in the optical birefringence, signaling the second-order nature of the N-SmA transition. The effect of the coupling between the nematic and smectic-A order parameters on the optical birefringence near the N-SmA transition is also discussed. In a temperature range of about 4K above and below the N-SmA transition, the pretransitional evidence for the N-SmA coupling have been detected. From the analysis of the optical birefringence data above and below the N-SmA transition by means of various fitting expressions we test the validity of the scaling relation λ=1-α between the critical exponent λ describing the limiting behavior of the nematic order parameter

  11. A rapid birefringence method for measuring suspended CaCO 3 concentrations in seawater

    NASA Astrophysics Data System (ADS)

    Guay, Christopher K. H.; Bishop, James K. B.

    2002-01-01

    The extreme birefringence of calcium carbonate (CaCO 3) relative to other major components of marine particulate matter provides a basis for making optical in situ measurements of particulate inorganic carbon (PIC) in seawater. This concept was tested with a benchtop spectrophotometer equipped with a 1- and 10-cm path length sample cell and modified with linear polarizers to measure the birefringence of suspended particles. Sample suspensions containing 3-100% CaCO 3 (by weight) were prepared from calcareous marine sediment material and varying amounts of non-birefringent diatomaceous earth. The samples ranged in total suspended material from 0.003 to 249 mg l -1 and PIC from 0.03 to 1820 μmol CaCO 3 l -1. A positive relationship was observed between birefringence and PIC, with response falling off as the total particle concentration and the relative abundance of non-CaCO 3 particles in the sample increased. Sensitivity increased linearly with optical path length, and absolute detection limits of 0.2-0.4 and 0.04-0.08 μmol CaCO 3 l -1, respectively, were determined for path lengths of 1- and 10-cm based on the intrinsic signal noise of the modified spectrophotometer. Conventional (i.e., non-polarized) transmittance measurements were used to correct the birefringence signal for the sensitivity loss due to interference from scattering and absorption. Without further modification, this spectrophotometer-based method can be used (with a 10-cm cell) to quantify PIC in most surface ocean waters—including those influenced by coccolithophore blooms. The spectrophotometer results define performance requirements and design parameters for an in situ instrument capable of operating over the oceanic range of PIC.

  12. The measurement system of birefringence and Verdet constant of optical fiber

    NASA Astrophysics Data System (ADS)

    Huang, Yi; Chen, Li; Guo, Qiang; Pang, Fufei; Wen, Jianxiang; Shang, Yana; Wang, Tingyun

    2013-12-01

    The Faraday magneto-optical effect of optical fiber has many applications in monitoring magnetic field and electric current. When a linearly polarized light propagates in the direction of a magnetic field, the plane of polarization will rotate linearly proportional to the strength of the applied magnetic field, which following the relationship of θF =VBl. θF is the Faraday rotation angle, which is proportional to the magnetic flux density B and the Verdet constant V . However, when the optical fiber contains the effect of linear birefringence, the detection of Faraday rotation angle will depend on the line birefringence. In order to determine the Verdet constant of an optical fiber under a linear birefringence, the fiber birefringence needs to be accurately measured. In this work, a model is applied to analyze the polarization properties of an optical fiber by using the Jones matrix method. A measurement system based on the lock-in amplifier technology is designed to test the Verdet constant and the birefringence of optical fiber. The magnetic field is produced by a solenoid with a DC current. A tunable laser is intensity modulated with a motorized rotating chopper. The actuator supplies a signal as the phase-locked synchronization reference to the signal of the lock-in amplifier. The measurement accuracy is analyzed and the sensitivity of the system is optimized. In this measurement system, the Verdet constant of the SMF-28 fiber was measured to be 0.56±0.02 rad/T·m at 1550nm. This setup is well suitable for measuring the high signal-to-noise ratio (SNR) sensitivity for lock-in amplifier at a low magnetic field strength.

  13. Highly birefringent chalcogenide optical fiber for polarization-maintaining in the 3-8.5 µm mid-IR window.

    PubMed

    Caillaud, Celine; Gilles, Clement; Provino, Laurent; Brilland, Laurent; Jouan, Thierry; Ferre, Simon; Carras, Mathieu; Brun, Mickael; Mechin, David; Adam, Jean-Luc; Troles, Johann

    2016-04-18

    A highly birefringent polarization-maintaining chalcogenide microstructured optical fiber (MOF) covering the 3-8.5 µm wavelength range has been realized for the first time. The fiber cross-section consists of 3 rings of circular air holes with 2 larger holes adjacent to the core. Birefringence properties are calculated by using the vector finite-element method and are compared to the experimental ones. The group birefringence is 1.5x10-3 and fiber losses are equal to 0.8 dB/m at 7.55 µm. PMID:27137239

  14. Large birefringence and polarization holographic gratings formed in photocross-linkable polymer liquid crystals comprising bistolane mesogenic side groups

    SciTech Connect

    Emoto, Akira; Matsumoto, Taro; Shioda, Tatsutoshi; Ono, Hiroshi; Yamashita, Ayumi; Kawatsuki, Nobuhiro

    2009-10-01

    Polarization gratings with large birefringence are formed in photoreactive polymer liquid crystals with bistolane moiety and terminal cinnamic acid moiety by the use of polarized ultraviolet interference light and subsequent annealing. The polarized ultraviolet light causes the axis-selective photoreaction between the cinnamic acid groups and subsequent annealing induce the reorientation of peripheral molecules without cross-linking along the cross-linked groups. Long bistolane mesogenic moiety exhibits large birefringence in comparison with a biphenyl mesogenic moiety, the value of the induced birefringence in the bistolane mesogenic liquid crystalline (LC) polymer is strongly dependent on both the grating constant and the wavelength of the reconstruction light.

  15. Investigations on the SR method growth, etching, birefringence, laser damage threshold and dielectric characterization of sodium acid phthalate single crystals

    NASA Astrophysics Data System (ADS)

    Senthil, A.; Ramasamy, P.; Verma, Sunil

    2011-03-01

    Optically good quality semi-organic single crystal of sodium acid phthalate (NaAP) was successfully grown by Sankaranarayanan-Ramasamy (SR) method. Transparent, colourless <0 0 1> oriented unidirectional bulk single crystals of diameters 10 and 20 mm and length maximum up to 75 mm were grown by the SR method. The grown crystals were subjected to various characterization studies such as etching, birefringence, laser damage threshold, UV-vis spectrum and dielectric measurement. The value of birefringence and quality were ascertained by birefringence studies.

  16. PCF Based Sensor with High Sensitivity, High Birefringence and Low Confinement Losses for Liquid Analyte Sensing Applications

    PubMed Central

    Ademgil, Huseyin; Haxha, Shyqyri

    2015-01-01

    In this paper, we report a design of high sensitivity Photonic Crystal Fiber (PCF) sensor with high birefringence and low confinement losses for liquid analyte sensing applications. The proposed PCF structures are designed with supplementary elliptical air holes in the core region vertically-shaped V-PCF and horizontally-shaped H-PCF. The full vectorial Finite Element Method (FEM) simulations performed to examine the sensitivity, the confinement losses, the effective refractive index and the modal birefringence features of the proposed elliptical air hole PCF structures. We show that the proposed PCF structures exhibit high relative sensitivity, high birefringence and low confinement losses simultaneously for various analytes. PMID:26694408

  17. Polarized light field microscopy: an analytical method using a microlens array to simultaneously capture both conoscopic and orthoscopic views of birefringent objects

    PubMed Central

    Oldenbourg, Rudolf

    2008-01-01

    For the comprehensive analysis of anisotropic materials, a new approach, called “polarized light field microscopy” is introduced. It uses an LC-PolScope to which a microlens array was added at the image plane of the objective lens. The system is patterned after the “light field microscope” that achieves both lateral and axial resolution in thick specimens in a single camera exposure. In polarized light field microscopy, the microlens array generates a hybrid image consisting of an array of small conoscopic images, each sampling a different object area. Analysis of the conoscopic images reveals the birefringence of each object area as a function of the propagation direction of transmitted light rays. The principles and utility of the instrument that we are calling “light field LC-PolScope” are demonstrated with images of a thin, polycrystalline calcite film, revealing the azimuth and inclination angle of the optic axis for many crystals simultaneously, including crystals with diameters as small as 2 µm. Compared to traditional conoscopy and related methods, the vastly improved throughput and quantitative analysis afforded by the light field LC-PolScope make it the instrument of choice for measuring 3-dimensional birefringence parameters of complex structures. PMID:18754996

  18. Determination of birefringence and slow axis distribution using an interferometric measurement system with liquid crystal phase shifter.

    PubMed

    Nose, Toshiaki; Kamata, Keisuke; Takeuchi, Toru; Okano, Keiju; Fujita, Naoko; Muraguchi, Hajime; Ozaki, Noriaki; Honma, Michinori; Ito, Ryouta

    2014-11-01

    It is known that liquid crystal (LC) cells are useful as compact and easy-to-handle phase shifters that are readily coupled into the optics of standard microscope systems. Here, a uniformly aligned molecular LC phase shifter is introduced into a polarization microscope to attain a birefringence imaging system, using the phase-shift interferometric technique. Since the birefringence can be determined accurately only when the optical axis of the sample is parallel or perpendicular to the slow axis (variable axis) of the LC phase shifter, an improved data analysis method is proposed for determining the birefringence independently of the direction; a simple method of determining the slow axis distribution is also demonstrated. Measurements of the birefringence and slow axis distribution properties of a potato starch particle are demonstrated to confirm the novel determination method. PMID:25402881

  19. Spectral-domain measurement of the strain sensitivity of phase modal birefringence of polarization-maintaining optical fibers

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Cezary

    2016-09-01

    The paper presents a new and simple method of measuring the strain sensitivity of phase modal birefringence (dΔn/dε) of polarization maintaining fibers (PMFs). The method is based on measuring the spectral strain sensitivity of a strain sensor in the configuration of a Sagnac interferometer with a PMF. The measured spectral strain sensitivity of the sensor is used to determine the strain sensitivity of phase modal birefringence and the polarimetric strain sensitivity of the PMF. In addition, a new procedure for determining the sign of the strain sensitivity of phase and group modal birefringence of a PMF. Using this method, measurements of the strain sensitivity of modal birefringence of PMFs were performed: a PM-PCF and a Bow-Tie fiber, in the wavelength range 1460-1600 nm. A comparison of the results of these measurements with results obtained using other methods for the same types of fibers is presented.

  20. Universal compensation of the non-reciprocal circular birefringence in a retracing path by a mirrored quarter-wave plate

    NASA Astrophysics Data System (ADS)

    Martinelli, Mario; Martelli, Paolo; Fasiello, Annalaura

    2016-08-01

    A quarter-wave plate combined with a mirror realizes a pure rotator on the reflected beam, hence it realizes the same polarization transformation of a Porro prism, which has been recently demonstrated as a universal compensator for the non-reciprocal circular birefringence present in a retracing path. In the present work, the mirrored quarter-wave plate has been experimentally proved to effectively compensate for the non-reciprocal circular birefringence introduced by a variable Faraday rotator.

  1. Dense arrays of microscopic optical vortex generators from femtosecond direct laser writing of radial birefringence in glass

    NASA Astrophysics Data System (ADS)

    Brasselet, Etienne; Royon, Arnaud; Canioni, Lionel

    2012-04-01

    We report on the generation of permanent singular light mode converters at the microscale using femtosecond direct laser writing in photo-thermo-refractive glass. It relies on the irreversible light-induced radial birefringence in the bulk of the material. The ability of such birefringence pattern to convert the spin angular momentum of light into orbital optical angular momentum is exploited to demonstrate the production of large arrays of optical vortex generators with surface densities up to 104cm-2.

  2. 3-D TECATE/BREW: Thermal, stress, and birefringent ray-tracing codes for solid-state laser design

    SciTech Connect

    Gelinas, R.J.; Doss, S.K.; Nelson, R.G.

    1994-07-20

    This report describes the physics, code formulations, and numerics that are used in the TECATE (totally Eulerian code for anisotropic thermo-elasticity) and BREW (birefringent ray-tracing of electromagnetic waves) codes for laser design. These codes resolve thermal, stress, and birefringent optical effects in 3-D stationary solid-state systems. This suite of three constituent codes is a package referred to as LASRPAK.

  3. A birefringence study of changes in myosin orientation during relaxation of skinned muscle fibers induced by photolytic ATP release.

    PubMed Central

    Peckham, M; Ferenczi, M A; Irving, M

    1994-01-01

    The birefringence of isolated skinned fibers from rabbit psoas muscle was measured continuously during relaxation from rigor produced by photolysis of caged ATP at sarcomere length 2.8-2.9 microns, ionic strength 0.1 M, 15 degrees C. Birefringence, the difference in refractive index between light components polarized parallel and perpendicular to the fiber axis, depends on the average degree of alignment of the myosin head domain with the fiber axis. After ATP release birefringence increased by 5.8 +/- 0.7% (mean +/- SE, n = 6) with two temporal components. A small fast component had an amplitude of 0.9 +/- 0.2% and rate constant of 63 s-1. By the completion of this component, the instantaneous stiffness had decreased to about half the rigor value, and the force response to a step stretch showed a rapid (approximately 1000 s-1) recovery phase. Subsequently a large slow birefringence component with rate constant 5.1 s-1 accompanied isometric force relaxation. Inorganic phosphate (10 mM) did not affect the fast birefringence component but accelerated the slow component and force relaxation. The fast birefringence component was probably caused by formation of myosin.ATP or myosin.ADP.Pi states that are weakly bound to actin. The average myosin head orientation at the end of this component is slightly more parallel to the fiber axis than in rigor. PMID:7811926

  4. 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.

  5. Polarized light imaging of birefringence and diattenuation at high resolution and high sensitivity

    PubMed Central

    Mehta, Shalin B.; Shribak, Michael; Oldenbourg, Rudolf

    2013-01-01

    Polarized light microscopy provides unique opportunities for analyzing the molecular order in man-made and natural materials, including biological structures inside living cells, tissues, and whole organisms. 20 years ago, the LC-PolScope was introduced as a modern version of the traditional polarizing microscope enhanced by liquid crystal devices for the control of polarization, and by electronic imaging and digital image processing for fast and comprehensive image acquisition and analysis. The LCPolScope is commonly used for birefringence imaging, analyzing the spatial and temporal variations of the differential phase delay in ordered and transparent materials. Here we describe an alternative use of the LC-PolScope for imaging the polarization dependent transmittance of dichroic materials. We explain the minor changes needed to convert the instrument between the two imaging modes, discuss the relationship between the quantities measured with either instrument, and touch on the physical connection between refractive index, birefringence, transmittance, diattenuation, and dichroism. PMID:24273640

  6. A novel synthesis approach for birefringent filters having arbitrarily amplitude transmittances

    NASA Astrophysics Data System (ADS)

    Halassi, Abde Rezzaq; Hamdi, Rachid; Bendimerad, Djalal Falih; Benkelfat, Badr-Eddine

    2016-06-01

    In this paper, we present a novel procedure for the synthesis of a filter having an arbitrarily specified amplitude transmittance. The filter configuration consists of N birefringent stages placed between a polarizer and an analyzer, with each stage containing an identical section and a variable section. An additional variable section is placed in front of the analyzer. The synthesis procedure is based on the resolution of a generalized nonlinear equation system directly deducted from the Jones matrix formalism to determine the angles of each stage, the angle of the analyzer and the phase shifts of the variable sections. A typical example of a 6-stage birefringent filter having an arbitrarily non-symmetric amplitude transmittance is shown and the opto-geometrical parameters are given to demonstrate the efficiency of the proposed synthesis procedure. The results obtained show an excellent agreement with those developed in the literature.

  7. Current sensing using circularly birefringent twisted solid-core photonic crystal fiber.

    PubMed

    Beravat, R; Wong, G K L; Xi, X M; Frosz, M H; St J Russell, P

    2016-04-01

    Continuously twisted solid-core photonic crystal fiber (PCF) exhibits pure circular birefringence (optical activity), making it ideal for current sensors based on the Faraday effect. By numerical analysis, we identify the PCF geometry for which the circular birefringence (which scales linearly with twist rate) is a maximum. For silica-air PCF, this occurs at a shape parameter (diameter-to-spacing ratio of the hollow channels) of 0.37 and a scale parameter (spacing-to-wavelength) of 1.51. This result is confirmed experimentally by testing a range of different structures. To demonstrate the effectiveness of twisted PCF as a current sensor, a length of fiber is placed on the axis of a 7.6 cm long solenoid, and the Faraday rotation is measured at different values of dc current. The system is then used to chart the wavelength dependence of the Verdet constant. PMID:27192315

  8. 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

  9. Terahertz-field-induced optical birefringence in common window and substrate materials.

    PubMed

    Sajadi, Mohsen; Wolf, Martin; Kampfrath, Tobias

    2015-11-01

    We apply intense terahertz (THz) electromagnetic pulses with field strengths exceeding 2 MV cm(-1) at ~1 THz to window and substrate materials commonly used in THz spectroscopy and determine the induced optical birefringence. Materials studied are diamond, sapphire, magnesium oxide (MgO), polymethylpentene (TPX), low-density polyethylene (LDPE), silicon nitride membrane (SiN) and crystalline quartz. We observe a Kerr-effect-type transient birefringence in all samples, except in quartz and Si, where, respectively, a linear electrooptic signal and a response beyond the perturbative regime are found. We extract the nonlinear refractive indices and the electrooptic coefficient (in the case of quartz) of these materials and discuss implications for their use as windows or substrates in THz pump-optical probe spectroscopy. PMID:26561167

  10. A Compact Dual-Crystal Modulated Birefringence-Measurement System for Microgravity Applications

    NASA Technical Reports Server (NTRS)

    Mackey, Jeffrey R.; Das, Kamal K.; Anna, Shelley L.; McKinley, Gareth H.

    1999-01-01

    A compact modulated birefringence-measurement system has been developed for use in microgravity fluid physics applications with non-Newtonian fluids such as polymer solutions. This instrument uses a dual-crystal transverse electro-optical modulator capable of modulation frequencies in excess of 100 MHz. The two crystals are modulated 180 deg. out of phase from each other, The theoretical framework governing the development of this instrument using the Mueller-Stokes polarization matrices is discussed. Several ground-based experiments are performed to compare this system with the theoretical results. Results from this transverse electro-optical modulator-based birefringence-measurement system agree well with the theory. The instrument is also very stable and robust, making it suitable for the extreme acceleration environment to be encountered in a NASA Black Brandt sounding rocket.

  11. Thermal dependence of stress-induced birefringence in single mode optical fibers

    NASA Technical Reports Server (NTRS)

    Berthold, J. W., III; Thompson, L. B.

    1984-01-01

    Measurements of the change in stress-induced birefringence with temperature in single mode optical fibers are reported. The fibers examined include those with low residual stress birefringence that have circular and elliptical cores. A section of each fiber was placed under constant load with weights and heated inside a furnace. Polarized light was coupled into and out of the fiber ends outside the furnace. Two mutually perpendicular polarization components were analyzed and detected at the fiber output end. Changes in the detected signal levels were monitored as a function of the temperature of the single mode fiber stressed under constant load. Discussion of results and applications to localized stress measurements at high temperatures are presented.

  12. Birefringence-balanced polarimetric optical fiber sensor for high-temperature measurements

    NASA Technical Reports Server (NTRS)

    Wang, Anbo; Wang, George Z.; Murphy, Kent A.; Claus, Richard O.

    1992-01-01

    A birefringence-balanced polarimetric multimode fiber temperature sensor is proposed and demonstrated. Two single-crystal sapphire rods are incorporated into the sensor head. They are connected end to end in such a way that the slow axis of the first rod is aligned with the fast axis of the second rod, referred to as the referencing rod. Since the lengths of the two rods are chosen to be almost the same, the original birefringence of the first rod is balanced by that of the second rod. A light-emitting diode serves as the light source. This sensor has been experimentally demonstrated for high-temperature measurements as high as 1500 C. A sensitivity of 5 C has been obtained.

  13. Polarization holograms in a bifunctional amorphous polymer exhibiting equal values of photoinduced linear and circular birefringences.

    PubMed

    Provenzano, Clementina; Pagliusi, Pasquale; Cipparrone, Gabriella; Royes, Jorge; Piñol, Milagros; Oriol, Luis

    2014-10-01

    Light-controlled molecular alignment is a flexible and useful strategy introducing novelty in the fields of mechanics, self-organized structuring, mass transport, optics, and photonics and addressing the development of smart optical devices. Azobenzene-containing polymers are well-known photocontrollable materials with large and reversible photoinduced optical anisotropies. The vectorial holography applied to these materials enables peculiar optical devices whose properties strongly depend on the relative values of the photoinduced birefringences. Here is reported a polarization holographic recording based on the interference of two waves with orthogonal linear polarization on a bifunctional amorphous polymer that, exceptionally, exhibits equal values of linear and circular birefringence. The peculiar photoresponse of the material coupled with the holographic technique demonstrates an optical device capable of decomposing the light into a set of orthogonally polarized linear components. The holographic structures are theoretically described by the Jones matrices method and experimentally investigated. PMID:25187982

  14. Characterization of temperature-dependent birefringence in polarization maintaining fibers based on Brillouin dynamic gratings

    NASA Astrophysics Data System (ADS)

    Kim, Yong Hyun; Song, Kwang Yong

    2015-07-01

    Temperature dependence of birefringence in various types of polarization-maintaining fibers (PMF's) is rigorously investigated by the spectral analysis of Brillouin dynamic grating (BDG). PANDA, Bowtie, and PM photonic crystal fibers are tested in the temperature range of -30 to 150 ºC, where nonlinear temperature dependence is quantified for each fiber to an accuracy of ±7.6 × 10-8. It is observed that the amount of deviation from the linearity varies according to the structural parameters of the PMF's and the existence of acrylate jacket. Experimental confirmation of the validity of the BDG-based birefringence measurement is also presented in comparison to the periodic lateral force method.

  15. A note on the birefringence angle estimation in CMB data analysis

    NASA Astrophysics Data System (ADS)

    Gruppuso, A.; Maggio, G.; Molinari, D.; Natoli, P.

    2016-05-01

    Parity violating physics beyond the standard model of particle physics induces a rotation of the linear polarization of photons. This effect, also known as cosmological birefringence (CB), can be tested with the observations of the cosmic microwave background (CMB) anisotropies which are linearly polarized at the level of 5–10%. In particular CB produces non-null CMB cross correlations between temperature and B mode-polarization, and between E- and B-mode polarization. Here we study the properties of the so called D-estimators, often used to constrain such an effect. After deriving the framework of both frequentist and Bayesian analysis, we discuss the interplay between birefringence and weak-lensing, which, albeit parity conserving, modifies pre-existing TB and EB cross correlation.

  16. A complex-polarization-propagator protocol for magneto-chiral axial dichroism and birefringence dispersion.

    PubMed

    Cukras, Janusz; Kauczor, Joanna; Norman, Patrick; Rizzo, Antonio; Rikken, Geert L J A; Coriani, Sonia

    2016-05-21

    A computational protocol for magneto-chiral dichroism and magneto-chiral birefringence dispersion is presented within the framework of damped response theory, also known as complex polarization propagator theory, at the level of time-dependent Hartree-Fock and time-dependent density functional theory. Magneto-chiral dichroism and magneto-chiral birefringence spectra in the (resonant) frequency region below the first ionization threshold of R-methyloxirane and l-alanine are presented and compared with the corresponding results obtained for both the electronic circular dichroism and the magnetic circular dichroism. The additional information content yielded by the magneto-chiral phenomena, as well as their potential experimental detectability for the selected species, is discussed. PMID:27118603

  17. Cross-phase-modulation-instability band gap in a birefringence-engineered photonic-crystal fiber

    NASA Astrophysics Data System (ADS)

    Kibler, B.; Amrani, F.; Morin, P.; Kudlinski, A.

    2016-01-01

    We report the cancellation of the cross-phase-modulation-instability (XPMI) gain over a large spectral window (which we term the XPMI band gap) in a highly birefringent photonic-crystal fiber with zero group birefringence. The XPMI ceases to occur when single-frequency pumping of orthogonally polarized modes takes place in such a spectral band gap whose frequency bandwidth depends on the pump power itself. The suppression of XPMI sidebands is confirmed experimentally when Raman scattering remains negligible. At high powers the Raman Stokes wave, generated by the pump, implies novel dual-frequency pump configurations with large group-velocity mismatch, thus leading to another type of Raman-induced XPMI sidebands. The experimental results are in good agreement with analytical phase-matching calculations and numerical simulations.

  18. Highly birefringent phase-shifted fiber Bragg gratings inscribed with femtosecond laser.

    PubMed

    He, Jun; Wang, Yiping; Liao, Changrui; Wang, Qiaoni; Yang, Kaiming; Sun, Bing; Yin, Guolu; Liu, Shen; Zhou, Jiangtao; Zhao, Jing

    2015-05-01

    We demonstrate a highly birefringent phase-shifted fiber Bragg grating (PS-FBG) inscribed in H2-free fiber with a near-infrared femtosecond Gaussian laser beam and uniform phase mask. The PS-FBG was fabricated from an ordinary fiber Bragg grating (FBG) in a case in which overexposure was applied. The spectral evolution from FBG to FS-FBG was observed experimentally with a decrease in transmission loss at dip wavelength, blueshift of the dip wavelength, decrease in the cladding mode loss, and an increase in the insertion loss. A high birefringence was demonstrated experimentally with the existence of PS-FBG only in TM polarization. The formation of the PS-FBG may be due to a negative index change induced by the higher intensity in the center of the Gaussian laser beam. PMID:25927770

  19. Real-time imaging of action potentials in nerves using changes in birefringence

    PubMed Central

    Badreddine, Ali H.; Jordan, Tomas; Bigio, Irving J.

    2016-01-01

    Polarized light can be used to measure the electrical activity associated with action potential propagation in nerves, as manifested in simultaneous dynamic changes in their intrinsic optical birefringence. These signals may serve as a tool for minimally invasive neuroimaging in various types of neuroscience research, including the study of neuronal activation patterns with high spatiotemporal resolution. A fast linear photodiode array was used to image propagating action potentials in an excised portion of the lobster walking leg nerve. We show that the crossed-polarized signal (XPS) can be reliably imaged over a ≥2 cm span in our custom nerve chamber, by averaging multiple-stimulation signals, and also in single-scan real-time “movies”. This demonstration paves the way toward utilizing changes in the optical birefringence to image more complex neuronal activity in nerve fibers and other organized neuronal tissue. PMID:27231635

  20. Real-time imaging of action potentials in nerves using changes in birefringence.

    PubMed

    Badreddine, Ali H; Jordan, Tomas; Bigio, Irving J

    2016-05-01

    Polarized light can be used to measure the electrical activity associated with action potential propagation in nerves, as manifested in simultaneous dynamic changes in their intrinsic optical birefringence. These signals may serve as a tool for minimally invasive neuroimaging in various types of neuroscience research, including the study of neuronal activation patterns with high spatiotemporal resolution. A fast linear photodiode array was used to image propagating action potentials in an excised portion of the lobster walking leg nerve. We show that the crossed-polarized signal (XPS) can be reliably imaged over a ≥2 cm span in our custom nerve chamber, by averaging multiple-stimulation signals, and also in single-scan real-time "movies". This demonstration paves the way toward utilizing changes in the optical birefringence to image more complex neuronal activity in nerve fibers and other organized neuronal tissue. PMID:27231635

  1. Pulsed laser induced birefringence switching in a biopolymer matrix containing azo-dye molecules

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Ziemienczuk, Marta; Miniewicz, Andrzej

    2011-07-01

    All optical switching has been studied using the Optical Kerr Effect (OKE) configuration in a biopolymer matrix containing an azo-dye: the Disperse Orange 3 (DO3). The biopolymer system consisted of a deoxyribonucleic acid blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride is suitable for optical quality thin film fabrication. The excitation beams inducing birefringence were delivered from a continuous wave laser at 532 nm and another nanosecond pulsed Nd: YAG laser. The birefringence was instantaneously monitored under crossed polarizer system by a weak non-absorbed light from a cw He-Ne laser working at 632.8 nm. Fast all optical switching process (in the range of microseconds) and excellent reversibility have been observed.

  2. The temperature dependence of the optical anisotropy in magnetic fluids: birefringence and dichroism

    NASA Astrophysics Data System (ADS)

    Yusuf, N. A.; Manasrah, D. A.; Abdallah, M. A.; Abu-Safia, H.; Abu-Aljarayesh, I.

    1994-11-01

    The temperature dependence of birefringence, δ, and dichroism, Δ A, in Fe 3O 4 Isopar-M based magnetic fluids have been investigated in the temperature range 100 < T < 320 K and in magnetic fields up to 3 kOe. The results show that birefringence and dichroism for a given concentration and at a given field are zero below a certain temperature Ts, and then both increase with temperature until they reach a maximum at a temperature Tm, and then decrease with temperature for T > Tm. The values of Tm and Ts are found to vary with concentration and the applied field. The results also show that δ- H2 and Δ A-H2 curves deviate from linearity. This deviation is attributed to interparticle interactions, the orientation of pre-existing clusters, and the field-induced chain formation.

  3. Simulation of birefringence effects on the dominant transversal laser resonator mode caused by anisotropic crystals.

    PubMed

    Asoubar, Daniel; Zhang, Site; Wyrowski, Frank

    2015-06-01

    Birefringence effects can have a significant influence on the polarization state as well as on the transversal mode structure of laser resonators. This work introduces a flexible, fast and fully vectorial algorithm for the analysis of resonators containing homogeneous, anisotropic optical components. It is based on a generalization of the Fox and Li algorithm by field tracing, enabling the calculation of the dominant transversal resonator eigenmode. For the simulation of light propagation through the anisotropic media, a fast Fourier Transformation (FFT) based angular spectrum of plane waves approach is introduced. Besides birefringence effects, this technique includes intra-crystal diffraction and interface refraction at crystal surfaces. The combination with numerically efficient eigenvalue solvers, namely vector extrapolation methods, ensures the fast convergence of the method. Furthermore a numerical example is presented which is in good agreement to experimental measurements. PMID:26072756

  4. Zero-birefringence photosensitive poly(arylene ether) for optical waveguides

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Dan; Zhong, Zhen-Xin; Kim, Jang Joo; Lee, Myong-Hoon

    2005-01-01

    Novel photosensitive fluorinated poly(arylene ether) containing chalcone unit (F-PAECh) in the main chain was synthesized from decafluorinated chalcone and fluorinated bisphenol at low temperature for polymer optical waveguide application. Upon UV irradiation on the resulting polymer film, [2+2] cycloaddition of chalocone moiety induced the anisotropic decrease of the refractive indices (nTE and nTM) accompanied with crosslinking of polymer film. The decrease was more significant in in-plane direction than out-of-plane direction, and consequently, zero birefringence was obtained with 4.5 min of exposure. Zero-birefringence as well as its excellent optical properties of F-PAECh makes it a promising candidate material for use in high-performance wavelength division multiplexing components such as polarization-independent arrayed waveguide gratings and Bragg wavelength filters.

  5. Nonlinear temperature dependence of glue-induced birefringence in polarization maintaining FBG sensors

    NASA Astrophysics Data System (ADS)

    Hopf, Barbara; Koch, Alexander W.; Roths, Johannes

    2016-05-01

    Glue-induced stresses decrease the accuracy of surface-mounted fiber Bragg gratings (FBG). Significant temperature dependent glue-induced birefringence was verified when a thermally cured epoxy-based bonding technique had been used. Determining the peak separation of two azimuthally aligned FBGs in PM fibers combined with a polarization resolved measurement set-up in a temperature range between -30°C and 150°C revealed high glue-induced stresses at low temperatures. Peak separations of about 60 pm and a nonlinear temperature dependence of the glue-induced birefringence due to stress relaxation processes and a visco-elastic behavior of the used adhesive have been shown.

  6. Design for birefringent filter with 8-channel for Space Solar Telescope

    NASA Astrophysics Data System (ADS)

    Jiang, Yuesong; Song, Guofeng; Ai, Guoxiang

    2002-03-01

    The principles of birefringent filter (BF) which consists of 8-channel and will be used in Space Solar Telescope (SST) is described in this article. The BF will be the main focus plane instrument of the payload of SST. It is a kind of birefringent filter with Polaroid replaced by polarizing beam splitter. It permits observations of solar vector magnetic field or line-of-sight velocity fields in any Fraunhofer line between the wavelength from 3900 to 6600 Å with half width from 0.03 to 0.12 Å. It can be turned across the spectral line to obtain line profiles of two-dimensional field of view with 8 channels. Because of this, we also call the BF with 8-channel as Two-Dimensional Spectrograph (TDS). This article also describes the analysis of mechanical and thermal control of the TDS. In the final, a new polarimeter of this system is introduced.

  7. Low birefringent magneto-optical waveguides fabricated via organic-inorganic sol-gel process

    NASA Astrophysics Data System (ADS)

    Choueikani, F.; Royer, F.; Douadi, S.; Skora, A.; Jamon, D.; Blanc, D.; Siblini, A.

    2009-09-01

    This paper is devoted to the study and the characterization of novel magneto-optical waveguides prepared via organic-inorganic sol-gel process. Thin silica/zirconia films doped with magnetic nanoparticles were coated on glass substrate using dip-coating technique. After annealing, samples were UV-treated. Two different techniques were used to measure their properties: m-lines spectroscopy and free space ellipsometry. Results evidence low refractive index waveguides that combine a low modal birefringence (2×10-4) with a Faraday rotation around 15 °/cm (φ = 0.1%). The low birefringence is obtained with a soft UV treatment and a graded intrinsic anisotropy is evidenced for films thicker than 5 μm. Therefore, we prove that the organic-inorganic sol-gel approach is very promising to realize magneto-optical waveguides with a non-reciprocal functionality such as TE-TM mode conversion.

  8. Polarization-maintaining fiber pulse compressor by birefringent hollow-core photonic bandgap fiber.

    PubMed

    Shirakawa, Akira; Tanisho, Motoyuki; Ueda, Ken-Ichi

    2006-12-11

    Structural birefringent properties of a hollow-core photonic-bandgap fiber were carefully investigated and applied to all-fiber chirped-pulse amplification as a compressor. The group birefringence of as high as 6.9x10(-4) and the dispersion splitting by as large as 149 ps/nm/km between the two principal polarization modes were observed at 1557 nm. By launching the amplifier output to one of the polarization modes a 17-dB polarization extinction ratio was obtained without any pulse degradation originating from polarization-mode dispersion. A hybrid fiber stretcher effectively compensates the peculiar dispersion of the photonic-bandgap fiber and pedestal-free 440-fs pulses with a 1-W average power and 21-nJ pulse energy were obtained. Polarization-maintaining fiber-pigtail output of high-power femtosecond pulses is useful for various applications. PMID:19529631

  9. First Light for the Near-Infrared Narrow-Band Tunable Birefringent Filter of the Big Bear Solar Observatory

    NASA Astrophysics Data System (ADS)

    Cao, W.; Hartkorn, K.; Ma, J.; Wang, J.; Xu, Y.; Spirock, T.; Denker, C.; Wang, H.

    2005-05-01

    A new near-infrared, narrow-band tunable birefringent filter has been developed by BBSO/NJIT. This filter, one of the first Lyot filters in the near-infrared, has a FWHM of about 2.5 ~Å at the design wavelength of 1.5648 μm and is used to observe the deepest levels of the photosphere. New techniques were employed in the design, including liquid crystal retarders to tune the center wavelength in range of ± 100 ~Å. After finishing the calibration and evaluation of the filter at the Evans Facility of the NSO at Sacramento Peak, high spatial resolution filtergrams and imaging spectroscopy observations were carried out at the Dunn Solar Telescope of NSO in December 2004 with the use of the high-order Adaptive Optics System. For some of these observations, the Lyot filter was combined with a Fabry-Perot Etalon to achieve a much higher spectral resolution. We discuss the calibration methods and present some preliminary observation results.

  10. Birefringence arising from the reorientation of the polarizability anisotropy of molecules in collisionless gases

    NASA Technical Reports Server (NTRS)

    Lin, C. H.; Heritage, J. P.; Gustafson, T. K.; Chiao, R. Y.; Mctague, J. P.

    1976-01-01

    The refractive-index change in a collisionless gas is evaluated from the Stark shifts of the rotational energy levels that arise from the polarizability anisotropy. In the limit of an extremely-short-duration excitation, a multilevel coherent effect results in delayed refractive-index bursts. Both stationary and transient responses of this birefringence to an optical field are considered for symmetric-top molecules, with particular emphasis on the special case of linear molecules.

  11. Semiconductor laser with a birefringent external cavity for information systems with wavelength division multiplexing

    SciTech Connect

    Paranin, V D; Matyunin, S A; Tukmakov, K N

    2013-10-31

    The spectrum of a semiconductor laser with a birefringent external Gires – Tournois cavity is studied. The generation of two main laser modes corresponding to the ordinary and extraordinary wave resonances is found. It is shown that the radiation spectrum is controlled with a high energy efficiency without losses for spectral filtration. The possibility of using two-mode lasing in optical communication systems with wavelength division multiplexing is shown. (control of laser radiation parameters)

  12. Microwave photonic phase shifter based on birefringence effects in a semiconductor optical amplifier.

    PubMed

    Chen, Han; Sun, Mingming; Ding, Yi; Sun, Xiaohan

    2013-09-01

    A continuously tunable microwave photonic (MWP) phase shifter based on birefringence effects in a semiconductor optical amplifier (SOA) is presented and the theoretical fundamentals of the design are explained. This proposed device provides a high efficiency phase-shift tuning range beyond 2π rad by controlling the SOA launch power. A prototype of the MWP phase shifter with a frequency of 10 GHz and 2π rad tuning range is experimentally demonstrated. PMID:23988932

  13. Non-osteoporotic women with low-trauma fracture present altered birefringence in cortical bone.

    PubMed

    Ascenzi, Maria-Grazia; Chin, Jesse; Lappe, Joan; Recker, Robert

    2016-03-01

    Areal bone mineral density (BMD) by DXA, although an important index, does not accurately assess risk of fragility fracture. Another bone structural parameter, the orientation of type I collagen, is known to add to risk determination, independently of BMD. Accordingly, we investigated the Haversian systems of transiliac crest biopsies from non-osteoporotic women with low-trauma fractures, matched to healthy women without fracture by age and BMD. We employed circularly polarized light (CPL) microscopy because 1) each of the extinct and bright birefringent signals of CPL corresponds to a specific collagen arrangement; and 2) CPL can employ magnification suitable to provide data, of manageable size, from the whole cortical component of a section of biopsy. Under CPL, the coaxial layers of osteons, called lamellae, appear either birefringent extinct or bright. On a section transverse to the Haversian system, the extinct lamella comprises mainly collagen forming small angles, and the bright lamella comprises mainly collagen forming large angles, relative to the general orientation of the Haversian system. We performed semi-automatic morphometry for birefringent and structural parameters for which we computed intra- and inter-observer errors. The statistical analysis used a linear mixed model to compare fracturing and non-fracturing groups while addressing pairing of fracturing and non-fracturing subjects, and linear regression to assess differences between matched subjects. We found significant reduction in 1) lamellar width and area for extinct lamella and bright lamella; 2) percentage of extinct birefringence in osteons, and 3) single osteon area; in the fracturing group; and in lamellar width in the fracturing subject of all pairs. Our results evidence the need to investigate, in a larger sample of subjects, the distribution of collagen orientation as a parameter diagnostic of increased fracture risk. PMID:26514952

  14. Electric field induced birefringence in non-aqueous dispersions of mineral nanorods.

    PubMed

    de la Cotte, Alexis; Merzeau, Pascal; Kim, Jong Wook; Lahlil, Khalid; Boilot, Jean-Pierre; Gacoin, Thierry; Grelet, Eric

    2015-09-01

    Lanthanum phosphate (LaPO4) nanorods dispersed in the non-aqueous solvent of ethylene glycol form a system exhibiting large intrinsic birefringence, high colloidal stability and the ability to self-organize into liquid crystalline phases. In order to probe the electro-optical response of these rod dispersions we study here the electric-field-induced birefringence, also called Kerr effect, for a concentrated isotropic liquid state with an in-plane a.c. sinusoidal electric field, in conditions of directly applied (electrodes in contact with the sample) or externally applied (electrodes outside the sample cell) fields. Performing an analysis of the electric polarizability of our rod-like particles in the framework of Maxwell-Wagner-O'Konski theory, we account quantitatively for the coupling between the induced steady-state birefringence and the electric field as a function of the voltage frequency for both sample geometries. The switching time of this non-aqueous transparent system has been measured, and combined with its high Kerr coefficients and its features of optically isotropic "off-state" and athermal phase behavior, this represents a promising proof-of-concept for the integration of anisotropic nanoparticle suspensions into a new generation of electro-optical devices. PMID:26189711

  15. Measurement of birefringence of optical materials using a wedged plate interferometer

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Perera, G. M.; George, M. C.; Venkateswarlu, Putcha

    1990-01-01

    A nondestructive technique for measuring the birefringence of optical materials such as calcite using wedged plate interferometer is presented. The sample needed for measuring the refractive index must be polished in the form of a parallel plate. The method is based on the measurement of the longitudinal displacement of the focus when the parallel plate is inserted in a converging beam of light. The displacement of the focus is a measure of the refractive index of the optical material. In the case of a uniaxial crystal, the displacement of the focus for the extraordinary ray is different from the displacement of the focus for the ordinary ray. Hence the birefringence of the crystal is determined by measuring the difference between the two focii. It is possible to obtain an accuracy up to 0.0002 in the measurement of birefringence depending on the sample thickness. The method should find its application for the characterization of new crystals in various material research and crystal growth laboratories.

  16. X-ray Birefringence Imaging of Materials with Anisotropic Molecular Dynamics.

    PubMed

    Palmer, Benjamin A; Edwards-Gau, Gregory R; Kariuki, Benson M; Harris, Kenneth D M; Dolbnya, Igor P; Collins, Stephen P; Sutter, John P

    2015-02-01

    The X-ray birefringence imaging (XBI) technique, reported very recently, is a sensitive tool for spatially resolved mapping of the local orientational properties of anisotropic materials. In this paper, we report the first XBI measurements on materials that undergo anisotropic molecular dynamics. Using incident linearly polarized X-rays with energy close to the Br K-edge, the X-ray birefringence is dictated by the orientational properties of the C-Br bonds in the material. We focus on two materials (urea inclusion compounds containing 1,8-dibromooctane and 1,10-dibromodecane guest molecules) for which the reorientational dynamics of the brominated guest molecules (and hence the reorientational dynamics of the C-Br bonds) are already well characterized by other experimental techniques. The XBI results demonstrate clearly that, for the anisotropic molecular dynamics in these materials, the effective X-ray optic axis for the X-ray birefringence phenomenon is the time-averaged resultant of the orientational distribution of the C-Br bonds. PMID:26261979

  17. Heterodyne double-channel polarimeter for mapping birefringence and thickness of flat glass panels

    SciTech Connect

    Protopopov, Vladimir V.; Cho, Sunghoon; Kim, Kwangso; Lee, Sukwon; Kim, Hyuk; Kim, Daesuk

    2006-05-15

    A new cross-polarized heterodyne optical technique is developed for two-dimensional (2D) simultaneous mapping of both birefringence and thickness variations in large flat glass panels commonly used in liquid-crystal displays (LCDs). Weak depolarization of a linearly polarized probe beam due to glass birefringence is detected by means of heterodyne mixing of the two cross-polarized and frequency shifted waves generated by Zeeman-type laser. Amplitude variations of the transmitted laser beam due to interference of the partial waves reflected from the both sides of a sample provide information about glass thickness. Measurements are being performed at the intermediate frequency of 2.3 MHz, providing several orders of magnitude higher speed of data acquisition with respect to traditional polarimeters. That high speed of measurements makes it possible to perform quality assessment of LCD glass panels not only in few randomly chosen points as it was in common practice before but to obtain entire 2D maps of both birefringence and thickness variations with millimeter scale spatial resolution. The medium-scale prototype of the LCD glass inspection system is developed and tested. Design and performance of the prototype are described.

  18. Tuning of liquid-crystal birefringence using a square ac variable frequency voltage

    NASA Astrophysics Data System (ADS)

    Hamdi, Rachid; Falih Bendimerad, Djalal; Benkelfat, Badr-Eddine; Vinouze, Bruno

    2015-10-01

    We demonstrate that the birefringence of the liquid-crystal cell (LCC) can be varied by applying different frequency values of a single applied ac square voltage. For the experimental evaluation of the birefringence, associated with a certain wavelength λ, as a function of the frequency F LCC of the electrical signal applied to the LCC, we use, for the first time to our knowledge, what we call here a frequency-dependent transmission technique. It consists in measuring the transmission responses between crossed and parallel polarizers as a function of the frequency F LCC. Experimental tests were carried out using a 7 μm-thick E63 nematic LCC and a laser source emitting at λ = 1.55 μm with a launch power of -3 dBm. The tuning voltage V LCC applied to the LCC is an alternative square wave electrical signal whose frequency ranges from 0.5 to 15 kHz. The peak to peak amplitude of the electrical signal is 5 V. The curve of the measured variations of the optical path difference of the LCC versus the frequency F LCC has a positive slope. Application to the tuning of the center wavelength of the transmission response of a one stage hybrid birefringent filter is shown as a proof-of-principle test.

  19. Simultaneous measurement of refractive index and thickness of birefringent wave plates.

    PubMed

    Yeh, Yen-Liang

    2008-04-01

    A nondestructive measurement system based on a position sensing detector (PSD) and a laser interferometer for determining the thickness and refractive indices of birefringent optical wave plates has been developed. Unlike previous methods presented in the literature, the proposed metrology system allows the refractive index and thickness properties of the optical plate to be measured simultaneously. The experimental results obtained for the e-light and o-light refractive indices of a commercially available birefringent optical wave plate with refractive indices of n(o)=1.542972 and n(e)=1.552033 are found to be accurate to within 0.004132 and 0.000229, respectively. Furthermore, the experimentally derived value of the wave plate thickness deviates by no more than 0.9 microm from the analytically derived value of 453.95 microm. Overall, the experimental results confirm that the proposed metrology system provides a simple yet highly accurate means of obtaining simultaneous measurements of the refractive indices and thickness of birefringent optical wave plates. PMID:18382573

  20. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media.

    PubMed

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

    2012-04-20

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles' performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications. PMID:22456180

  1. Retardance of bilayer anisotropic samples consisting of well-aligned cylindrical scatterers and birefringent media

    NASA Astrophysics Data System (ADS)

    Guo, Yihong; Zeng, Nan; He, Honghui; Liu, Celong; Du, E.; He, Yonghong; Ma, Hui

    2016-05-01

    Both cylindrical scatterers and birefringent media may contribute to the anisotropy of tissue, where anisotropy can be characterized using polarization techniques. Our previous studies have shown that a layer of well-aligned cylindrical scatterers displays anisotropic properties similar to those of a piece of birefringent media, whose equivalent extraordinary axis is along the axial direction of the cylinders. We focused on a sample consisting of two layers of anisotropic media, with each layer having a different orientation; the characteristics of this sample were representative of the properties of multilayer fibrous tissues. Using a Mueller matrix decomposition method, we examined in detail how the total retardance and the equivalent extraordinary axis of the bilayered sample varied with changes in the retardance of the two layers and the direction of the extraordinary axis. The results of this study showed that, in such bilayer samples, a layer of well-aligned cylindrical scatterers generated a retardance that behaved exactly like the retardance generated by a piece of birefringent media. The simulated results were also confirmed by the results of experiments using aligned glass fibers.

  2. Polarization birefringence measurements for characterizing the myocardium, including healthy, infarcted, and stem-cell-regenerated tissues

    NASA Astrophysics Data System (ADS)

    Wood, Michael F. G.; Ghosh, Nirmalya; Wallenburg, Marika A.; Li, Shu-Hong; Weisel, Richard D.; Wilson, Brian C.; Li, Ren-Ke; Vitkin, I. Alex

    2010-07-01

    Myocardial infarction leads to structural remodeling of the myocardium, in particular to the loss of cardiomyocytes due to necrosis and an increase in collagen with scar formation. Stem cell regenerative treatments have been shown to alter this remodeling process, resulting in improved cardiac function. As healthy myocardial tissue is highly fibrous and anisotropic, it exhibits optical linear birefringence due to the different refractive indices parallel and perpendicular to the fibers. Accordingly, changes in myocardial structure associated with infarction and treatment-induced remodeling will alter the anisotropy exhibited by the tissue. Polarization-based linear birefringence is measured on the myocardium of adult rat hearts after myocardial infarction and compared with hearts that had received mesenchymal stem cell treatment. Both point measurement and imaging data show a decrease in birefringence in the region of infarction, with a partial rebound back toward the healthy values following regenerative treatment with stem cells. These results demonstrate the ability of optical polarimetry to characterize the micro-organizational state of the myocardium via its measured anisotropy, and the potential of this approach for monitoring regenerative treatments of myocardial infarction.

  3. Application of field-modulated birefringence and light scattering to biosensing

    NASA Astrophysics Data System (ADS)

    Strong, Louis H.; Hall, Daniel B.; Edson, Clark M.; Nguyen, Hiep-hoa; Whitt, Michael A.; Varadi, Gyula

    2011-03-01

    Superparamagnetic nanoparticles (NPs) coated with surface ligands are shown to be an effective means to impart magnetic field modulation to optical signals from targeted receptor complexes. The modulated signals they produce can be used for a number of important high throughput applications in bio-sensing including: detecting (weaponized) viruses, screening recombinant libraries of proteins, identifying pathogenic conversions of microbes, and monitoring gene amplification. We compare the results of two dynamic methods of measuring target binding to NPs: birefringence and field modulated light scattering (FMLS). These measurements reflect complementary manifestations of NP alignment (orientation) and de-alignment (relaxation) dynamics. Birefringence originates from the specific crystalline properties of a small subset of paramagnetic NPs (for example, maghemite) when oriented in a magnetic field. Upon quenching the field, it decays at a rate exhibiting the Debye-Stokes-Einstein rotational relaxation constant of target-NP complexes. Birefringence relaxation reflects the particle dynamics of the mixed suspension of NPs, with signal components weighted in proportion to the free and complexed NP size distributions. FMLS relaxation signals, on the other hand, originate predominately from the inherent optical anisotropy of the target complexes, show little contribution from non-complexed NPs when the targets are more optically anisotropic than the NPs, and provide a more direct and accurate method for determining target receptor concentrations. Several illustrations of the broad range of applications possible using these dynamic measurements and the kind of information to be derived from each detection modality will be discussed.

  4. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media

    NASA Astrophysics Data System (ADS)

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M.; Luna, Mónica; Briones, Fernando

    2012-04-01

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles’ performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications.

  5. Birefringent dual-frequency laser Doppler velocimeter using a low-frequency lock-in amplifier technique for high-resolution measurements.

    PubMed

    Zhu, Hongbin; Chen, Junbao; Guo, Dongmei; Xia, Wei; Hao, Hui; Wang, Ming

    2016-06-01

    A birefringent dual-frequency laser with a half-intracavity has been used to develop a laser Doppler velocimeter (LDV). The developed LDV utilizes a new signal-processing method based on a lock-in amplifier to achieve high-resolution velocity measurements and the discrimination of positive and negative velocities. Theoretical analysis and simulation results are presented. The velocity measurement experiments by using a high-precision linear stage are performed to verify the performance of the LDV. Compared with the previous dual-frequency LDVs, the average velocity resolution of the developed LDV is improved from 0.31 mm/s to 0.028 mm/s for a target without the rotational velocity. The measurement results show that our new technique can offer a powerful instrument for metrology sciences. PMID:27411198

  6. Contribution of counterions and degree of ionization for birefringence creation and relaxation kinetics parameters of PAH/PAZO films

    SciTech Connect

    Raposo, Maria Monteiro Timóteo, Ana Rita; Ribeiro, Paulo A.; Ferreira, Quirina; Botelho do Rego, Ana Maria

    2015-09-21

    Photo induced birefringent materials can be used to develop optical and conversion energy devices, and consequently, the study of the variables that influences the creation and relaxation of birefringence should be carefully analyzed. In this work, the parameters of birefringence creation and relaxation kinetics curves obtained on layer-by-layer (LBL) films, prepared from azo-polyectrolyte poly[1-[4-(3-carboxy-4 hydroxyphenylazo) benzene sulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and poly(allylamine hydrochloride)(PAH), are related with the presence of counterions and the degree of ionization of the polyelectrolytes. Those kinetics curves obtained on PAH/PAZO LBL films, prepared from PAH solutions with different pHs and maintaining the pH of PAZO solution constant at pH = 9, were analyzed taking into account the films composition which was characterized by X-ray photoelectron spectroscopy. The creation and relaxation birefringence curves are justified by two processes: one associated to local mobility of the azobenzene with a characteristic time 30 s and intensity constant and other associated with polymeric chains mobility with the characteristic time and intensity decreasing with pH. These results allow us to conclude that the birefringence creation process, associated to local mobility of azobenzenes is independent of the degree of ionization and of number of counterions or co-ions present while the birefringence creation process associated to mobility of chains have its characteristic time and intensity dependent of both degree of ionization and number of counterions. The birefringence relaxation processes are dependent of the degree of ionization. The analysis of the films composition revealed, in addition, the presence of a protonated secondary or tertiary amine revealing that PAZO may have positive charges and consequently a zwitterionic behavior.

  7. Time Circular Birefringence in Time-Dependent Magnetoelectric Media

    PubMed Central

    Zhang, Ruo-Yang; Zhai, Yan-Wang; Lin, Shi-Rong; Zhao, Qing; Wen, Weijia; Ge, Mo-Lin

    2015-01-01

    Light traveling in time-dependent media has many extraordinary properties which can be utilized to convert frequency, achieve temporal cloaking, and simulate cosmological phenomena. In this paper, we focus on time-dependent axion-type magnetoelectric (ME) media, and prove that light in these media always has two degenerate modes with opposite circular polarizations corresponding to one wave vector , and name this effect “time circular birefringence” (TCB). By interchanging the status of space and time, the pair of TCB modes can appear simultaneously via “time refraction” and “time reflection” of a linear polarized incident wave at a time interface of ME media. The superposition of the two TCB modes causes the “time Faraday effect”, namely the globally unified polarization axes rotate with time. A circularly polarized Gaussian pulse traversing a time interface is also studied. If the wave-vector spectrum of a pulse mainly concentrates in the non-traveling-wave band, the pulse will be trapped with nearly fixed center while its intensity will grow rapidly. In addition, we propose an experimental scheme of using molecular fluid with external time-varying electric and magnetic fields both parallel to the direction of light to realize these phenomena in practice. PMID:26329928

  8. Corneal birefringence measured by spectrally resolved Mueller matrix ellipsometry and implications for non-invasive glucose monitoring.

    PubMed

    Westphal, Peter; Kaltenbach, Johannes-Maria; Wicker, Kai

    2016-04-01

    A good understanding of the corneal birefringence properties is essential for polarimetric glucose monitoring in the aqueous humor of the eye. Therefore, we have measured complete 16-element Mueller matrices of single-pass transitions through nine porcine corneas in-vitro, spectrally resolved in the range 300…1000 nm. These ellipsometric measurements have been performed at several angles of incidence at the apex and partially at the periphery of the corneas. The Mueller matrices have been decomposed into linear birefringence, circular birefringence (i.e. optical rotation), depolarization, and diattenuation. We found considerable circular birefringence, strongly increasing with decreasing wavelength, for most corneas. Furthermore, the decomposition revealed significant dependence of the linear retardance (in nm) on the wavelength below 500 nm. These findings suggest that uniaxial and biaxial crystals are insufficient models for a general description of the corneal birefringence, especially in the blue and in the UV spectral range. The implications on spectral-polarimetric approaches for glucose monitoring in the eye (for diabetics) are discussed. PMID:27446644

  9. Flow-induced birefringence measurement system using dual-crystal transverse electro-optic modulator for microgravity fluid physics applications

    NASA Technical Reports Server (NTRS)

    Mackey, Jeffrey R.

    1999-01-01

    We have developed a new instrument that can measure fast transient birefringence and polymer chain orientation angle in complex fluids. The instrument uses a dual-crystal transverse electro-optic modulator with the second crystal's modulation voltage applied 180 deg out of phase from that of the first crystal. In this manner, the second crystal compensates for the intrinsic static birefringence of the first crystal, and it doubles the modulation depth. By incorporating a transverse electro-optic modulator with two lithium-niobate (LiNbO3) crystals oriented orthogonal to each other with a custom-designed optical system, we have produced a very small robust instrument capable of fast transient retardation measurements. By measuring the sample thickness or optical path length through the sample, we can calculate the transient birefringence. This system can also measure dichroism. We have compared the calibration results and retardation and orientation angle measurements of this instrument with those of a photoelastic modulator (PEM) based system using a quarter wave plate and a high-precision 1/16-wave plate to simulate a birefringent sample. Transient birefringence measurements on the order of 10(exp -9) can be measured using either modulator.

  10. Optimized retinal nerve fiber layer segmentation based on optical reflectivity and birefringence for polarization-sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wang, Bingqing; Paranjape, Amit S.; Yin, Biwei; Liu, Shuang; Markey, Mia K.; Milner, Thomas E.; Rylander, H. Grady, III

    2011-09-01

    Segmentation of the retinal nerve fiber layer (RNFL) from swept source polarization-sensitive optical coherence tomography (SS-PSOCT) images is required to determine RNFL thickness and calculate birefringence. Traditional RNFL segmentation methods based on image processing and boundary detection algorithms utilize only optical reflectivity contrast information, which is strongly affected by speckle noise. We present a novel approach to segment the retinal nerve fiber layer (RNFL) using SS-PSOCT images including both optical reflectivity and phase retardation information. The RNFL anterior boundary is detected based on optical reflectivity change due to refractive index difference between the vitreous and inner limiting membrane. The posterior boundary of the RNFL is a transition zone composed of birefringent axons extending from retinal ganglion cells and may be detected by a change in birefringence. A posterior boundary detection method is presented that segments the RNFL by minimizing the uncertainty of RNFL birefringence determined by a Levenberg-Marquardt nonlinear fitting algorithm. Clinical results from a healthy volunteer show that the proposed segmentation method estimates RNFL birefringence and phase retardation with lower uncertainty and higher continuity than traditional intensity-based approaches.

  11. Corneal birefringence measured by spectrally resolved Mueller matrix ellipsometry and implications for non-invasive glucose monitoring

    PubMed Central

    Westphal, Peter; Kaltenbach, Johannes-Maria; Wicker, Kai

    2016-01-01

    A good understanding of the corneal birefringence properties is essential for polarimetric glucose monitoring in the aqueous humor of the eye. Therefore, we have measured complete 16-element Mueller matrices of single-pass transitions through nine porcine corneas in-vitro, spectrally resolved in the range 300…1000 nm. These ellipsometric measurements have been performed at several angles of incidence at the apex and partially at the periphery of the corneas. The Mueller matrices have been decomposed into linear birefringence, circular birefringence (i.e. optical rotation), depolarization, and diattenuation. We found considerable circular birefringence, strongly increasing with decreasing wavelength, for most corneas. Furthermore, the decomposition revealed significant dependence of the linear retardance (in nm) on the wavelength below 500 nm. These findings suggest that uniaxial and biaxial crystals are insufficient models for a general description of the corneal birefringence, especially in the blue and in the UV spectral range. The implications on spectral-polarimetric approaches for glucose monitoring in the eye (for diabetics) are discussed. PMID:27446644

  12. Influences of temperature and transport properties on the birefringence of CdGeAs2

    NASA Astrophysics Data System (ADS)

    Fischer, D. W.; Ohmer, M. C.; McCrae, J. E.

    1997-04-01

    We have directly measured the birefringence Δn of CdGeAs2 using polarized light interference spectra obtained in transmittance from 2.4 to 18 μm over a temperature range of 14-450 K. Four different samples, exhibiting a wide range of free carrier concentrations, were studied. It was found that free carriers can have a significant effect on the room-temperature birefringence. At 14 K, however, the data from all samples were virtually identical. The temperature dependence of Δn was obtained from a sample with low carrier concentration (≈1015/cm3) and high resistivity (9 Ω cm). Its temperature derivative d(Δn)/dT was determined at 50 K increments over the entire 14-450 K temperature range, and was found to vary from 2.6×10-5/K at 100 K to 5.1×10-5/K at 400 K. A least-squares fit to the data yielded a temperature coefficient for Δn of 8.2×10-8/K. Hall-effect measurements indicate that the resistivity, mobility, and carrier concentration all exhibit a significant temperature dependence. The resistivity for one sample increased by a factor of 108 when cooled from room temperature to 14 K. Our results suggest that previously published Δn values were probably obtained from samples with relatively high carrier concentrations, and that our results more accurately describe the true intrinsic birefringence of the material. The value of Δn decreases by 0.0004 per 1016 carriers a factor of 10 less than suggested by theory but still significantly large. The heavy to light hole effective mass ratio in the uppermost valence band was found to be 7.1.

  13. Birefringence issues with uniaxial crystals as last lens elements for high-index immersion lithography

    NASA Astrophysics Data System (ADS)

    Burnett, John H.; Benck, Eric C.; Kaplan, Simon G.; Sirat, Gabriel Y.; Mack, Chris

    2009-03-01

    We discuss the birefringence issues associated with use of crystalline sapphire, with uniaxial crystal structure, as a last lens element for high-index 193 nm immersion lithography. Sapphire is a credible high-index lens material candidate because with appropriate orientation and TE polarization the ordinary ray exhibits the required isotropic optical properties. Also, its material properties may give it higher potential to meet the stringent optical requirements compared to the potential of the principal candidate materials, cubic-symmetry LuAG and ceramic spinel. The TE polarization restriction is required anyway for hyper-NA imaging, due to TM-polarization contrast degradation effects. Further, the high uniaxial-structure birefringence of sapphire may offer the advantage that any residual TM polarization results in a relatively-uniform flare instead of contrast degradation. One issue with this concept is that spatial-dispersion-induced effects should cause some index anisotropy of the ordinary rays, in a way similar to the intrinsic birefringence (IBR) effects in cubic crystals, except that there is no ray splitting. We present the theory of this effect for the trigonal crystal structure of sapphire and discuss its implications for lithography optics. For this material the spatial-dispersion-induced effects are characterized by eight material parameters, of which three contribute to index anisotropy of the ordinary rays. Only one gives rise to azimuthal distortions, and may present challenges for correction. To assess the consequences of using sapphire as a last element, neglecting any IBR effects, we use lithography simulations to characterize the lithographic performance for a 1.7 NA design, and compare to that for LuAG.

  14. Chirality measurements using optical fibre long period gratings fabricated in high birefringent fibre

    NASA Astrophysics Data System (ADS)

    Korposh, S.; Tatam, R. P.; James, S. W.; Lee, S.-W.

    2015-07-01

    A Long period grating (LPG) with a period of 111 μm was fabricated in the highly birefringent (Hi-Bi) optical fibre with the aim of developing a sensor for chirality measurements. The LPG sensor was exposed to different concentrations of glucose D(+) and fructose D(-) in water, which have similar structures but exhibit opposite optical rotations, i.e. chirality. The behaviour of the resonance bands of the submodes corresponding to the two orthogonal polarization states was different depending on the chirality of the compound, thus allowing discrimination between two compounds.

  15. Reversible change of birefringence sign by optical and thermal processes in an azobenzene polymethacrylate

    SciTech Connect

    Rodriguez, F.J.; Sanchez, C.; Villacampa, B.; Alcala, R.; Cases, R.; Millaruelo, M.; Oriol, L.

    2005-01-10

    Birefringence ({delta}n) induced in an azobenzene polymethacrylate by combination of biphotonic and thermotropic processes has subsequently been changed in sign by room temperature illumination with linearly polarized blue light. The sign of {delta}n can be reversed again, by simply heating up the film to 100 deg. C. This change of {delta}n between positive and negative values can be repeated several times. Besides, by appropriate choice of film thickness and blue light irradiation conditions the same absolute value for positive and negative {delta}n values can be obtained.

  16. Birefringence images of polycrystalline films of human urine in early diagnostics of kidney pathology.

    PubMed

    Dubolazov, A V; Pashkovskaya, N V; Ushenko, Yu A; Marchuk, Yu F; Ushenko, V A; Novakovskaya, O Yu

    2016-04-20

    We propose an optical model of the Mueller-matrix description of mechanisms of optical anisotropy of polycrystalline films of urine, namely, optical activity and birefringence. The algorithm of reconstruction of distributions of parameters-optical rotation angles and phase shifts of the indicated anisotropy types-are elaborated upon. The objective criteria of differentiation of urine films taken from healthy donors and albuminuria patients by means of statistical analysis of such distributions are determined. The operational characteristics (sensitivity, specificity, and accuracy) of the Mueller-matrix reconstruction method of the optical anisotropy parameters are defined. PMID:27140137

  17. Cross-phase modulational instability induced by Raman scattering in highly birefringent fiber.

    PubMed

    Amrani, Foued; Kibler, Bertrand; Grelu, Philippe; Wabnitz, Stefan; Trillo, Stefano; Millot, Guy

    2013-12-15

    We report experimental and theoretical studies of Raman-induced cross-phase modulational instabilities (XPMI) in a high-birefringence, normally dispersive optical fiber. Experimental results reveal that the Raman-Stokes wave, generated by a quasi-CW pump beam, interacts with the latter to create a novel type of XPMI sidebands. These sidebands are characterized by a narrow gain bandwidth. The sideband frequencies are well reproduced by a linear stability analysis as well as by full numerical solutions of the coupled generalized nonlinear Schrödinger equations. PMID:24322249

  18. Compact static imaging spectrometer combining spectral zooming capability with a birefringent interferometer.

    PubMed

    Li, Jie; Zhu, Jingping; Qi, Chun; Zheng, Chuanlin; Gao, Bo; Zhang, Yunyao; Hou, Xun

    2013-04-22

    A compact static birefringent imaging spectrometer (BIS) with spectral zooming capability is presented. It based on two identical Wollaston prisms and has no slit. The most significant advantage of the BIS is that we can conveniently select spectral resolution to adapt to different application requirements and greatly reduce the size of the spectral image data for capturing, saving, transferring, and processing. Also, we show this configuration blend the advantage of a grating spectrometer and a Michelson interferometer: extremely compact, robust, wide free spectral range and very high throughput. PMID:23609723

  19. Numerical analysis of stress distribution in embedded highly birefringent PANDA fibers

    NASA Astrophysics Data System (ADS)

    Lesiak, Piotr; Woliński, Tomasz

    2015-09-01

    The paper presents numerical analysis compared with experimental data of influence of polymerization shrinkage on highly birefringent (HB) PANDA optical fibers embedded in a composite material. Since polymerization is a chemical process consisting in combining single molecules in a macromolecular compound [1], principal directions of the polymerization shrinkage depend on a number of the composite layers associated with this process. In this paper a detailed analysis of the piezo-optic effects occurring in HB optical fibers before and after the lamination process answers the question to what extent a degree of the material degradation can be properly estimated.

  20. Crystalline perfection, birefringence and laser damage threshold properties of piperidinium p-hydroxybenzoate

    SciTech Connect

    Sudhahar, S.; Zahid, I. MD; Kumar, M. Krishna; Kumar, R. Mohan

    2015-06-24

    Piperidinium p-hydroxybenzoate (PPHB) crystal was grown by slow evaporation method. Single crystal X-ray diffraction studies confirm that PPHB crystallizes in monoclinic crystal system with noncentrosymmetric space group Cc. The crystalline perfection of the grown crystal was evaluated by using high resolution X-ray diffractometry. UV-Visible transmission and birefringence studies were employed on the grown PPHB crystal. The laser induced damage threshold value was estimated using Nd:YAG laser. Thermal behavior of PPHB crystal has been investigated by TG-DTA analyses. Etching studies have been performed to assess the growth pattern of PPHB crystal.

  1. Exploiting cellophane birefringence to generate radially and azimuthally polarised vector beams

    NASA Astrophysics Data System (ADS)

    Kalwe, Johnston; Neugebauer, Martin; Ominde, Calvine; Leuchs, Gerd; Rurimo, Geoffrey; Banzer, Peter

    2015-03-01

    We exploit the birefringence of cellophane to convert a linearly polarised Gaussian beam into either a radially or azimuthally polarised beam. For that, we fabricated a low-cost polarisation mask consisting of four segments of cellophane. The fast axis of each segment is oriented appropriately in order to rotate the polarisation of the incident linearly polarised beam as desired. To ensure the correct operation of the polarisation mask, we tested the polarisation state of the generated beam by measuring the spatial distribution of the Stokes parameters. Such a device is very cost efficient and allows for the generation of cylindrical vector beams of high quality.

  2. Stray magnetic-field response of linear birefringent optical current sensors

    NASA Astrophysics Data System (ADS)

    MacDougall, Trevor W.; Hutchinson, Ted F.

    1995-07-01

    It is well known that the line integral, describing Faraday rotation in an optical medium, reduces to zero at low frequencies for a closed path that does not encircle a current source. If the closed optical path possesses linear birefringence in addition to Faraday rotation, the cumulative effects on the state of polarization result in a response to externally located current-carrying conductors. This effect can induce a measurable error of the order of 0.3% during certain steady-state operating conditions.

  3. Soliton-dark pulse pair formation in birefringent cavity fiber lasers through cross phase coupling.

    PubMed

    Shao, Guodong; Song, Yufeng; Zhao, Luming; Shen, Deyuan; Tang, Dingyuan

    2015-10-01

    We report on the experimental observation of soliton-dark pulse pair formation in a birefringent cavity fiber laser. Temporal cavity solitons are formed in one polarization mode of the cavity. It is observed that associated with each of the cavity solitons a dark pulse is induced on the CW background of the orthogonal polarization mode. We show that the dark pulse formation is a result of the incoherent cross polarization coupling between the soliton and the CW beam and has a mechanism similar to that of the polarization domain formation observed in the fiber lasers. PMID:26480138

  4. Pump Spectral Bandwidth, Birefringence, and Entanglement in Type-II Parametric Down Conversion

    DOE PAGESBeta

    Erenso, Daniel

    2009-01-01

    The twin photons produced by a type-II spontaneous parametric down conversion are well know as a potential source of photons for quantum teleportation due to the strong entanglement in polarization. This strong entanglement in polarization, however, depends on the spectral composition of the pump photon and the nature of optical isotropy of the crystal. By exact numerical calculation of the concurrence, we have shown that how pump photons spectral width and the birefringence nature of the crystal directly affect the degree of polarization entanglement of the twin photons.

  5. Digital polarization holograms with defined magnitude and orientation of each pixel's birefringence.

    PubMed

    Fratz, Markus; Giel, Dominik M; Fischer, Peer

    2009-04-15

    A new form of digital polarization holography is demonstrated that permits both the amplitude and the phase of a diffracted beam to be independently controlled. This permits two independent intensity images to be stored in the same hologram. To fabricate the holograms, a birefringence with defined retardance and orientation of the fast axis is recorded into a photopolymer film. The holograms are selectively read out by choosing the polarization state of the read beam. Polarization holograms of this kind increase the data density in holographic data storage and allow higher quality diffractive optical elements to be written. PMID:19370140

  6. 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.

  7. Vector Breathers in an Averaged Dispersion-Managed Birefringent Fiber System

    NASA Astrophysics Data System (ADS)

    Li, Ji-Tao; Han, Jin-Zhong; Zhang, Xian-Tu

    2015-07-01

    A variable-coefficient coupled nonlinear Schrödinger equation in an averaged dispersion-managed birefringent fiber is investigated. Based on the one-to-one correspondence between variable-coefficient and constant-coefficient equations, an analytical breather solution is derived. As an example to exhibit dynamical behaviors of solution, its controllable excitations including rear excitation, peak excitation and initial excitation are discussed. Supported by the Science and Technology Department of Henan Province under Grant No. 142300410043, and by the Education Department of Henan Province under Grant No. 13A140113

  8. The structural organization of dinucleosomes and oligonucleosomes. Electric dichroism and birefringence study.

    PubMed Central

    Houssier, C; Lasters, I; Muyldermans, S; Wyns, L

    1981-01-01

    The spatial organization of nucleosomes and linker DNA in dinucleosomes and oligonucleosomes of various chain lengths has been investigated through electric dichroism, birefringence and relaxation times measurements at low ionic strengths (0.5 to 2.2 mM). From the negative dichroism observed for all the samples, it is concluded that the nucleosome subunits in the oligonucleosome chain must lie with their disc planes closely parallel to the fibre axis. The large increase of the negative dichroism of dinucleosomes upon Hl removal is interpreted by the unwinding of the DNA tails and the internucleosomal segment. All the samples displayed, under bipolar pulses, a predominantly induced orientation mechanism. PMID:7312629

  9. Further comments on the effects of vacuum birefringence on the polarization of X-rays emitted from magnetic neutron stars

    NASA Technical Reports Server (NTRS)

    Chanan, G. A.; Novick, R.; Silver, E. H.

    1979-01-01

    The birefringence of the vacuum in the presence of strong (of the order of 1 teragauss) magnetic fields will in general affect the polarization of X-rays propagating through these fields. Two of the four Stokes parameters will vary so rapidly with wavelength as to be 'washed out' and unobservable, but the remaining two parameters will be unaffected. These results show that one conclusion of an earlier work is incorrect: Polarized X-ray emission from the surface of a magnetic neutron star will not in general be completely depolarized by the effects of vacuum birefringence. In particular, this birefringence has no effect on the linear polarization of cyclotron emission from the poles of magnetic neutron stars, and a similar result holds for synchrotron emission. More general cases of the propagation of polarized X-rays in magnetic fields are also discussed.

  10. Stress-induced birefringence and fabrication of in-fiber polarization devices by controlled femtosecond laser irradiations.

    PubMed

    Yuan, Lei; Cheng, Baokai; Huang, Jie; Liu, Jie; Wang, Hanzheng; Lan, Xinwei; Xiao, Hai

    2016-01-25

    Optical birefringence was created in a single-mode fiber by introducing a series of symmetric cuboid stress rods on both sides of the fiber core along the fiber axis using a femtosecond laser. The stress-induced birefringence was estimated to be 2.4 × 10(-4) at the wavelength of 1550 nm. By adding the desired numbers of stressed rods, an in-fiber quarter waveplate was fabricated with a insertion loss of 0.19 dB. The stress-induced birefringence was further explored to fabricate in-fiber polarizers based on the polarization-dependent long-period fiber grating (LPFG) structure. A polarization extinction ratio of more than 20 dB was observed at the resonant wavelength of 1523.9 nm. The in-fiber polarization devices may be useful in optical communications and fiber optic sensing applications. PMID:26832490

  11. Effects of Ellipticity Angle on Modulation Instabilities in Birefringent Optical Fibers

    NASA Astrophysics Data System (ADS)

    Jin-Hua, Li; K. W., Chow; Ping, Liu; Yong-Zheng, Hu; Ting-Ting, Sun

    2016-02-01

    Previous studies on modulation instabilities (MIs) in birefringent optical fibers focus on the ordinary linearly and circularly ones. This paper reports an analysis of MIs in the general elliptically birefringent fibers with the emphasis on investigating the effects of ellipticity angle (0° ≤ θ ≤ 90°). Both symmetric and antisymmetric CW states are considered. In the anomalous dispersion regime, for the symmetric (antisymmetric) CW states, we show that MI gain increases dramatically (reduces first and then enhances greatly) as the increment of θ. In the normal dispersion regime, for the both CW states, the distinctive feature is that the gain of the MI bands reduces first, vanishes at θ = 45°, reappears across this ellipticity angle, and quickly increases after then. Supported by the National Natural Science Foundation of China under Grant Nos. 11447113 and 11305031, Natural Science Foundation of Jiangsu Provincial Universities under Grant No. 14KJB140009, and the Startup Foundation for Introducing Talent of Nanjing University of Information Science and Technology under Grant No. 2241131301064

  12. Linear birefringence and dichroism measurement in oil-based Fe3O4 magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lin, Jing-Fung; Wang, Chia-Hung; Lee, Meng-Zhe

    2013-04-01

    To prepare dispersed Fe3O4 magnetic nanoparticles (MNPs), we adopt a co-precipitation method and consider surfactant amount, stirring speed, dispersion mode, and molar ratio of Fe3+/Fe2+. Via transmission electronic microscopy and X-ray diffractometry, we characterize the dispersibility and size of the products and determine the appropriate values of experimental parameters. The stirring speed is 1000 rpm in titration. There is simultaneous ultrasonic vibration and mechanical stirring in the titration and surface coating processes. The surfactant amount of oleic acid is 1.2 ml for molar ratios of Fe3+/Fe2+ as 1.7:1, 1.8:1, and 1.9:1. The average diameters of these Fe3O4 MNPs are 11 nm, and the ratios of saturation magnetization for these MNPs to that of bulk magnetite range from 45% to 65%, with remanent magnetization close to zero and low coercivity. Above all, the linear birefringence and dichroism measurements of the kerosene-based ferrofluid (FF) samples are investigated by a Stokes polarimeter. The influences of particle size distribution and magnetization in the birefringence and dichroism measurements of FFs are discussed.

  13. Periodic reversal of magneto-optic Faraday rotation on uniaxial birefringence crystal with ultrathin magnetic films

    NASA Astrophysics Data System (ADS)

    Su, C. W.; Chang, S. C.; Chang, Y. C.

    2013-07-01

    An experimental approach of inclined incidence magneto-optic Faraday effect observed in the polar plane is applied. Three samples containing ferromagnetic cobalt ultrathin films on a semiconductor zinc oxide (0001) single crystal substrate with in-plane and out-of-plane anisotropy are evaluated. Through the fine adjustment of crossed polarizers in the magneto-optic effect measurement completely recorded the detail optical and magneto-optical responses from the birefringent crystal substrate and the magnetic film, especially for the signal induced from the substrate with uniaxial optical axis. The angle dependency of interference phenomena periodically from the optical and magneto-optical responses is attributed to the birefringence even in the absence of a magnetic field. The new type of observation finds that the transmission Faraday intensity in the oblique incidence includes a combination of polarization rotations, which results from optical compensation from the substrate and magneto-optical Faraday effects from the film. The samples grown at different rates and examined by this method exhibit magnetic structure discriminations. This result can be applied in the advanced polarized-light technologies to enhance the spatial resolution of magnetic surfaces with microstructural information under various magnetic field direction.

  14. Irregular spin angular momentum transfer from light to small birefringent particles

    SciTech Connect

    Rothmayer, M.; Tierney, D.; Schmitzer, H.; Frins, E.; Dultz, W.

    2009-10-15

    The transfer of spin angular momentum from photons to small particles is a key experiment of quantum physics. The particles rotate clockwise or counterclockwise depending on the polarization of the light beam which holds them in an optical trap. We show that even perfectly disk shaped particles will in general not rotate with a constant angular speed. The particles will periodically accelerate and decelerate their rotational motion due to a varying spin angular momentum transfer from the light. Using the Poincare sphere we derive the equation of motion of a birefringent plate and verify the results by measuring the time dependent rotation of small crystals of Hg(I) iodide and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) in the trap of polarized optical tweezers. For small ellipticities of the polarized light in the tweezers the plate stops in a fixed orientation relative to the axes of the light ellipse. We discuss the origin of this halt and propose an application of small birefringent plates as self-adjusting optical retarders in micro-optics.

  15. Multiple scattering of polarized light in turbid birefringent media: a Monte Carlo simulation.

    PubMed

    Otsuki, Soichi

    2016-07-20

    Multiple scattering of polarized light in a birefringent turbid plane medium was studied using a Monte Carlo simulation. The reduced effective scattering Mueller matrix obtained in the simulation was factorized in two dimensions using the Lu-Chipman decomposition, yielding polarization parameters that exhibited dependences on the azimuth and the radial distance around the illumination point. We propose a double-scattering model for the propagation of polarized photons in turbid infinite plane media. When the birefringence slow axis is along the azimuth of 90° on the plane surface, the retardance becomes the largest negative along the azimuth of 0° and the largest positive along the azimuth of 90° and increases with increasing the azimuth from 0° to 90°. This azimuthal dependence may result from the overlap of the contributions from the light propagations vertical to, and lateral along, the plane surface. Thus, the dependences on the azimuth and the radial distance of the polarization parameters, such as the retardance, its orientation, optical rotation, and the depolarization coefficients, are correctly predicted. PMID:27463921

  16. Optical birefringence of liquid crystals for label-free optical biosensing diagnosis

    PubMed Central

    Nguyen, Tan Tai; Han, Gyeo-Re; Jang, Chang-Hyun; Ju, Heongkyu

    2015-01-01

    Purpose We present a polarization-sensitive optical detection platform for label-free quantitative optical biosensing diagnosis using liquid crystals (LCs). This is capable of determining quantitatively the optical birefringence of optical cells containing LCs, whose orientation depends on the immobilized biomolecules. Patients and methods This technique uses a polarization-dependent double-port detection without any polarizer at a single wavelength and removes the need of aligning optical cells of LCs in the azimuthal direction, with respect to the light path through the optical cell. Thus, this technique enables a stand-alone detection in a relatively compact format without an additional optical instrument, such as a retardation compensator, a Michael–Levy chart, and a spectrophotometer, in order to determine the optical birefringence quantitatively. Results We demonstrate that bovine serum albumin immobilized on the gold surface of the cell hybrid interfaces that support both homeotropic and planar anchoring of LCs causes optical phase retardation change which can be determined quantitatively. We also provide estimation of the zenithal orientation of LCs near the gold surface of the hybrid interfaces, based on the phase retardation determined. The estimated limit of bovine serum albumin detection is approximately 2.1 μM. Conclusion This optical technique with LCs can serve an optical platform for label-free quantitative diagnosis of proteins in a real time manner. PMID:26347013

  17. Birefringence and second harmonic generation on tendon collagen following red linearly polarized laser irradiation.

    PubMed

    Silva, Daniela Fátima Teixeira; Gomes, Anderson Stevens Leonidas; de Campos Vidal, Benedicto; Ribeiro, Martha Simões

    2013-04-01

    Regarding the importance of type I collagen in understanding the mechanical properties of a range of tissues, there is still a gap in our knowledge of how proteins perform such work. There is consensus in literature that the mechanical characteristics of a tissue are primarily determined by the organization of its molecules. The purpose of this study was to characterize the organization of non-irradiated and irradiated type I collagen. Irradiation was performed with a linearly polarized HeNe laser (λ = 632.8 nm) and characterization was undertaken using polarized light microscopy to investigate the birefringence and second harmonic generation to analyze nonlinear susceptibility. Rats received laser irradiation (P = 6.0 mW, I = 21.2 mW/cm(2), E ≈ 0.3 J, ED = 1.0 J/cm(2)) on their healthy Achilles tendons, which after were extracted to prepare the specimens. Our results show that irradiated samples present higher birefringence and greater non-linear susceptibility than non-irradiated samples. Under studied conditions, we propose that a red laser with polarization direction aligned in parallel to the tendon long axis promotes further alignment on the ordered healthy collagen fibrils towards the electric field incident. Thus, prospects for biomedical applications for laser polarized radiation on type I collagen are encouraging since it supports greater tissue organization. PMID:23247985

  18. Enhanced solar cell conversion efficiency using birefringent liquid crystal polymer homeotropic films from reactive mesogens.

    PubMed

    Wu, Gwomei; Hsieh, Li-Hang; Chien, How-Wen

    2013-01-01

    Novel birefringent liquid crystal polymer homeotropic films have been coated on semiconductor solar cells to improve the effective incident sunlight angles. The liquid crystal polymer precursor, based on reactive mesogens, is fluidic and flows like liquid. It would distribute uniformly on the solar cell sample surface by any traditional coating technique. The birefringence for light, due to the liquid crystal retardation properties, manipulated the optical length and the deflection of incident light, thus allowed an increase in the energy conversion efficiency. The expensive sunlight tracking systems could be avoided. The processing parameters can be tuned such as different mesogen concentrations and plate speeds of spin-coating. The results showed that the solar cell conversion efficiency was improved from 14.56% to 14.85% at an incident sunlight angle of 15°. It was further improved from 13.40% to 13.81% when the angle was 30°. The interesting angular dependency on solar cell efficiency enhancement has been evaluated. PMID:24232577

  19. Relaxation times and energy barriers of rubbing-induced birefringence in glass-forming polymers

    NASA Astrophysics Data System (ADS)

    Shiu, K. P.; Qin, Zongyi; Yang, Z.

    2008-12-01

    The relaxations of rubbing-induced birefringence (RIB) in several glass-forming polymers, including polycarbonate and polystyrene (PS) derivatives with various modifications to the phenyl ring side group, are studied. Significant relaxations of RIB are observed at temperatures well below the glass transition temperature T g . The relaxation times span a wide range from ˜ 10 s to probably geological time scale. Physical aging effects are absent in the RIB relaxations. The model proposed for the interpretation of RIB in PS describes well the RIB relaxations in all the polymers investigated here. The energy barriers are of the order of a few hundred kJ/mol and decrease with decreasing temperature, in opposition to the trend of Vogel-Fulcher form for polymer segmental relaxations above T g . The relaxation behaviors of different polymers are qualitatively similar but somewhat different in quantitative details, such as in the values of the saturated birefringence, the shape of the initial barrier density distribution functions, the rates of barrier decrease with decreasing temperature, and the dependence of relaxation times on temperature and parameter ξ , etc. The RIB relaxations are different from any of the other relaxations below T g that have been reported in the literature, such as dielectric relaxations or optical probe relaxations. A microscopic model for the relaxations of RIB is much desired.

  20. Birefringence compensation of two tandem-set Nd:YAG rods with different thermally induced features

    NASA Astrophysics Data System (ADS)

    Wang, You; Inoue, Koichi; Kan, Hirofumi; Ogawa, Takayo; Wada, Satoshi

    2009-12-01

    How to reduce the thermally induced effects in a solid-state rod is a critical assignment for the applications of high-powered diode-pumped solid-state lasers (DPSSLs). In this paper, we study the birefringence compensation in a solid-state laser system containing two tandem-set Nd:YAG rods with different thermally induced characteristics. By reason of the uneven emission wavelengths of the pump LDs, the thermal focal length of one Nd:YAG rod is about 1.3 times as much as that of the other in our study. Using a 90° quartz rotator and a pair of coupling lenses, we investigated the depolarization dependence on different laser structures. It has been found that the birefringence in two laser rods with such different thermally induced features can be excellently reduced by adopting an optimized lens configuration which is not a traditional telescope image system as usually adopted by many researchers. Both the theoretical analyses and the experimental results have demonstrated the performance of our approach. The conclusions have been thought to be useful for constructing a high-average-power laser oscillator with a near- TEM00 mode.

  1. Electric birefringence study of an amyloid fibril system: The short end of the length distribution

    NASA Astrophysics Data System (ADS)

    Rogers, S. S.; Venema, P.; van der Ploeg, J. P. M.; Sagis, L. M. C.; Donald, A. M.; van der Linden, E.

    2005-10-01

    In this article, a system of amyloid fibrils, based on the protein β-lactoglobulin, is studied by transient electric birefringence. Single pulses of an electric field were applied to the solution, and the initial rise and subsequent decay of birefringence analysed. The decay takes place on a range of relaxation times, and therefore contains information about the length distribution of fibrils in the system. The information can be extracted using theories of the electric polarisability of polyelectrolyte rods, since the fibrils are an example of these. Despite the long-standing complications of such theories, useful quantitative information about the system can still be obtained. Using the Fixman model of polyelectrolyte polarisability, we obtain a measurement of the short end of the length distribution which shows the fibril concentration as a function of length rising linearly from 0.02-2 μm. The short end of the length distribution was unobtainable in our previous study using rheo-optics (S.S. Rogers et al., Macromolecules 38, 2948 (2005)), but reasonable agreement between the two techniques shows they are complementary.

  2. Structural, optical and dynamical properties of a high birefringence laterally fluorinated terphenyl isothiocyanate

    NASA Astrophysics Data System (ADS)

    Sinha, D.; Mandal, P. K.; Dabrowski, R.

    2015-02-01

    A doubly fluorinated isothiocyanato butyl terphenyl compound exhibiting a broad range of the nematic and a narrow range of smectic phase has been investigated by X-ray, dielectric and optical methods and compared with the properties of singly and doubly fluorinated ethyl homologues to see the effect of fluorination and chain flexibility. Contrary to common perception, weak antiparallel correlation of molecules is observed in each compound both from X-ray and dielectric studies. Observed dielectric anisotropy is strong enough to ensure a driving voltage suitable for thin film transistor-based liquid crystal display. Measured splay elastic constant suggests that the present compound will exhibit the fastest response. Flip-flop mode relaxations are observed in a few hundred kHz to MHz range. All the compounds exhibit high birefringence (0.373-0.331). They also show high order parameters at low temperatures. These compounds are expected to be suitable for formulating high birefringence nematic mixtures for fast switching displays.

  3. Compact snapshot birefringent imaging Fourier transform spectrometer for remote sensing and endoscopy

    NASA Astrophysics Data System (ADS)

    Kudenov, Michael W.; Banerjee, Bhaskar; Chan, Victoria C.; Dereniak, Eustace L.

    2012-09-01

    The design and implementation of a compact multiple-image Fourier transform spectrometer (FTS) is presented. Based on the multiple-image FTS originally developed by A. Hirai, the presented device offers significant advantages over his original implementation. Namely, its birefringent nature results in a common-path interferometer which makes the spectrometer insensitive to vibration. Furthermore, it enables the potential of making the instrument ultra-compact, thereby improving the portability of the sensor. The theory of the birefringent FTS is provided, followed by details of its specific embodiment. A laboratory proof of concept of the sensor, designed and developed at the Optical Detection Lab, is also presented. Spectral measurements of laboratory sources are provided, including measurements of light-emitting diodes and gas-discharge lamps. These spectra are verified against a calibrated Ocean Optics USB2000 spectrometer. Other data were collected outdoors and of a rat esophagus, demonstrating the sensor's ability to resolve spectral signatures in both standard outdoor lighting and environmental conditions, as well as in fluorescence spectroscopy.

  4. Infrared birefringence imaging of residual stress and bulk defects in multicrystalline silicon

    SciTech Connect

    Ganapati, Vidya; Schoenfelder, Stephan; Castellanos, Sergio; Oener, Sebastian; Koepge, Ringo; Sampson, Aaron; Marcus, Matthew A.; Lai, Barry; Morhenn, Humphrey; Hahn, Giso; Bagdahn, Joerg; Buonassisi1, Tonio

    2010-05-05

    This manuscript concerns the application of infrared birefringence imaging (IBI) to quantify macroscopic and microscopic internal stresses in multicrystalline silicon (mc-Si) solar cell materials. We review progress to date, and advance four closely related topics. (1) We present a method to decouple macroscopic thermally-induced residual stresses and microscopic bulk defect related stresses. In contrast to previous reports, thermally-induced residual stresses in wafer-sized samples are generally found to be less than 5 MPa, while defect-related stresses can be several times larger. (2) We describe the unique IR birefringence signatures, including stress magnitudes and directions, of common microdefects in mc-Si solar cell materials including: {beta}-SiC and {beta}-Si{sub 3}N{sub 4} microdefects, twin bands, nontwin grain boundaries, and dislocation bands. In certain defects, local stresses up to 40 MPa can be present. (3) We relate observed stresses to other topics of interest in solar cell manufacturing, including transition metal precipitation, wafer mechanical strength, and minority carrier lifetime. (4) We discuss the potential of IBI as a quality-control technique in industrial solar cell manufacturing.

  5. Enhanced Solar Cell Conversion Efficiency Using Birefringent Liquid Crystal Polymer Homeotropic Films from Reactive Mesogens

    PubMed Central

    Wu, Gwomei; Hsieh, Li-Hang; Chien, How-Wen

    2013-01-01

    Novel birefringent liquid crystal polymer homeotropic films have been coated on semiconductor solar cells to improve the effective incident sunlight angles. The liquid crystal polymer precursor, based on reactive mesogens, is fluidic and flows like liquid. It would distribute uniformly on the solar cell sample surface by any traditional coating technique. The birefringence for light, due to the liquid crystal retardation properties, manipulated the optical length and the deflection of incident light, thus allowed an increase in the energy conversion efficiency. The expensive sunlight tracking systems could be avoided. The processing parameters can be tuned such as different mesogen concentrations and plate speeds of spin-coating. The results showed that the solar cell conversion efficiency was improved from 14.56% to 14.85% at an incident sunlight angle of 15°. It was further improved from 13.40% to 13.81% when the angle was 30°. The interesting angular dependency on solar cell efficiency enhancement has been evaluated. PMID:24232577

  6. Constraints on cosmological birefringence from PLANCK and Bicep2/Keck data

    NASA Astrophysics Data System (ADS)

    Gruppuso, A.; Gerbino, M.; Natoli, P.; Pagano, L.; Mandolesi, N.; Melchiorri, A.; Molinari, D.

    2016-06-01

    The polarization of cosmic microwave background (CMB) can be used to constrain cosmological birefringence, the rotation of the linear polarization of CMB photons potentially induced by parity violating physics beyond the standard model. This effect produces non-null CMB cross correlations between temperature and B mode-polarization, and between E- and B-mode polarization. Both cross-correlations are otherwise null in the standard cosmological model. We use the recently released 2015 PLANCK likelihood in combination with the Bicep2/Keck/Planck (BKP) likelihood to constrain the birefringence angle α. Our findings, that are compatible with no detection, read α = 0.0° ± 1.3° (stat) ± 1° (sys) for PLANCK data and α = 0.30° ± 0.27° (stat) ± 1° (sys) for BKP data. We finally forecast the expected improvements over present constraints when the PLANCK BB, TB and EB spectra at high l will be included in the analysis.

  7. Macroscopic birefringence in liquid crystals from novel cyanobacterial polysaccharide with an extremely high molecular weight

    NASA Astrophysics Data System (ADS)

    Okajima-Kaneko, Maiko; Hayasaka-Kaneko, Daisaku; Miyazato, Shinji; Kaneko, Tatsuo

    2007-05-01

    We report an efficient method for extraction of anionic polysaccharides (PS) from cyanobacteria, Aphanothece sacrum; we used a hot alkaline solution (0.01 N NaOH) as an elution solvent in the first step of the extraction and isopropanol as a precipitation solvent in the last step. Thin fibers of PS were obtained at a high yield (50-80 % to the weight of the raw cyanobacterial sample). The spectroscopy and elemental analyses indicated the PS contains fucose, uronic acids (14.2 % by a carbazole-sulfuric acid method), a sugar unit containing amides. The solution of PS with a concentration of 1 wt% showed a very high viscosity (80 000cps) implying a high molecular weight, and a strong macroscopic birefringence with a texture typical of nematic liquid crystals was confirmed by crossed-polarizing microscopy (more than 0.5 wt%). The PS from A. sacrum may form a special structure rigid-rod enough to show LC phase and macroscopic birefringence.

  8. High Magnetic Field-Induced Birefringence in Lyotropic Chromonic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Ostapenko, T.; Nastishin, Yu.; Gleeson, J. T.; Sprunt, S. N.; Lavrentovich, O. D.; Collings, P. J.

    2009-03-01

    We studied the effect of magnetic-field induced birefringence of a 14% solution of disodium cromoglycate (DSCG) in water at temperatures above the nematic-isotropic coexistence region. According to Landau-deGennes mean field theory, we expect to find a linear relationship between the inverse of the induced birefringence, δn, and the quantity (T-T*), where T* is the stability limit of the isotropic phase. Using the 31 T resistive magnet at the National High Magnetic Field Laboratory, we observed that, as we increase the temperature above the coexistence region, we deviate from this linear dependence. Our data shows that δn goes to zero, whereas Landau-deGennes predicts that δn should decrease asymptotically. This may be due to the lack of isodesmic aggregate formation at a finite temperature above the coexistence region.Supported by NSF (DMR-0710544 and DMR-0606160). Work performed at NHMFL, supported by NSF cooperative agreements DMR-0084173, the State of Florida and the DOE.

  9. The system spatial-frequency filtering of birefringence images of human blood layers

    NASA Astrophysics Data System (ADS)

    Ushenko, A. G.; Boychuk, T. M.; Mincer, O. P.; Angelsky, P. O.; Bodnar, N. B.; Oleinichenko, B. P.; Bizer, L. I.

    2013-09-01

    Among various opticophysical methods [1 - 3] of diagnosing the structure and properties of the optical anisotropic component of various biological objects a specific trend has been singled out - multidimensional laser polarimetry of microscopic images of the biological tissues with the following statistic, correlative and fractal analysis of the coordinate distributions of the azimuths and ellipticity of polarization in approximating of linear birefringence polycrystalline protein networks [4 - 10]. At the same time, in most cases, experimental obtaining of tissue sample is a traumatic biopsy operation. In addition, the mechanisms of transformation of the state of polarization of laser radiation by means of the opticoanisotropic biological structures are more varied (optical dichroism, circular birefringence). Hereat, real polycrystalline networks can be formed by different types, both in size and optical properties of biological crystals. Finally, much more accessible for an experimental investigation are biological fluids such as blood, bile, urine, and others. Thus, further progress of laser polarimetry can be associated with the development of new methods of analysis and processing (selection) of polarization- heterogeneous images of biological tissues and fluids, taking into account a wider set of mechanisms anisotropic mechanisms. Our research is aimed at developing experimental method of the Fourier polarimetry and a spatialfrequency selection for distributions of the azimuth and the ellipticity polarization of blood plasma laser images with a view of diagnosing prostate cancer.

  10. Numerical simulation of polarization-resolved second-harmonic microscopy in birefringent media

    NASA Astrophysics Data System (ADS)

    Gusachenko, Ivan; Schanne-Klein, Marie-Claire

    2013-11-01

    Polarization-resolved second-harmonic microscopy has recently emerged as a valuable technique for in situ imaging of collagen structure in tissues. Nevertheless, collagen-rich tissues such as tendon, ligament, skin dermis, bone, cornea, or artery exhibit a heterogeneous and anisotropic architecture that results in complex optical properties. While experimental evidence of polarization distortions has been reported in various tissues, the physics of second-harmonic imaging within such tissues is not fully understood yet. In this work, we performed numerical simulations of polarization-resolved second-harmonic generation in a strongly focused regime within a birefringent tissue. We show that vectorial components due to strong focusing have a rather small effect on the measurement of the second-harmonic tensorial response, while birefringence and optical dispersion may affect these measurements dramatically. We show indeed that a difference in the focal field distribution for ordinary and extraordinary waves results in different phase-matching conditions, which strongly affects the relative efficacy of second-harmonic generation for different polarizations. These results are of great interest for extracting reliable quantitative parameters from second-harmonic images.

  11. Three-dimensional structural and local birefringence imaging of the bovine meniscus by use of OCT and PSOCT

    NASA Astrophysics Data System (ADS)

    Guo, Shuguang; Xie, Tuqiang; Peavy, George M.; Wong, Brian J. F.; Chen, Zhongping

    2006-02-01

    Menisci are frequently injured. A small meniscus tear may progress to a deeper tear if not treated. We will present the capability of diagnosis of meniscus injuries with OCT and PSOCT and the performance improvement of OCT that benefits from both local birefringence imaging and 3-dimensional reconstructions.

  12. Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour

    NASA Astrophysics Data System (ADS)

    Villiger, Martin; Lorenser, Dirk; McLaughlin, Robert A.; Quirk, Bryden C.; Kirk, Rodney W.; Bouma, Brett E.; Sampson, David D.

    2016-07-01

    Identifying tumour margins during breast-conserving surgeries is a persistent challenge. We have previously developed miniature needle probes that could enable intraoperative volume imaging with optical coherence tomography. In many situations, however, scattering contrast alone is insufficient to clearly identify and delineate malignant regions. Additional polarization-sensitive measurements provide the means to assess birefringence, which is elevated in oriented collagen fibres and may offer an intrinsic biomarker to differentiate tumour from benign tissue. Here, we performed polarization-sensitive optical coherence tomography through miniature imaging needles and developed an algorithm to efficiently reconstruct images of the depth-resolved tissue birefringence free of artefacts. First ex vivo imaging of breast tumour samples revealed excellent contrast between lowly birefringent malignant regions, and stromal tissue, which is rich in oriented collagen and exhibits higher birefringence, as confirmed with co-located histology. The ability to clearly differentiate between tumour and uninvolved stroma based on intrinsic contrast could prove decisive for the intraoperative assessment of tumour margins.

  13. Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour.

    PubMed

    Villiger, Martin; Lorenser, Dirk; McLaughlin, Robert A; Quirk, Bryden C; Kirk, Rodney W; Bouma, Brett E; Sampson, David D

    2016-01-01

    Identifying tumour margins during breast-conserving surgeries is a persistent challenge. We have previously developed miniature needle probes that could enable intraoperative volume imaging with optical coherence tomography. In many situations, however, scattering contrast alone is insufficient to clearly identify and delineate malignant regions. Additional polarization-sensitive measurements provide the means to assess birefringence, which is elevated in oriented collagen fibres and may offer an intrinsic biomarker to differentiate tumour from benign tissue. Here, we performed polarization-sensitive optical coherence tomography through miniature imaging needles and developed an algorithm to efficiently reconstruct images of the depth-resolved tissue birefringence free of artefacts. First ex vivo imaging of breast tumour samples revealed excellent contrast between lowly birefringent malignant regions, and stromal tissue, which is rich in oriented collagen and exhibits higher birefringence, as confirmed with co-located histology. The ability to clearly differentiate between tumour and uninvolved stroma based on intrinsic contrast could prove decisive for the intraoperative assessment of tumour margins. PMID:27364229

  14. Reduction of birefringence in a skin-layer of injection molded polymer strips using CO{sub 2} laser irradiation

    SciTech Connect

    Kurosaki, Yasuo; Satoh, Isao; Saito, Takushi

    1995-12-31

    Injection molding of polymers is currently utilized for numerous industrial applications. Because of high productivity and stable quality of molded products, the injection-molding process makes the production costs lower, and therefore, is expected to spread more widely in the future. This paper deals with a technique for improving the optical quality of injection molded polymer products using radiative heating. The birefringence frozen in a skin-layer of the molded part was reduced by CO{sub 2} laser heating, and the efficiency of this technique was investigated experimentally. Namely, a simple numerical calculation was performed to estimate the heating efficiency of CO{sub 2} laser in the polymer, effects of radiation heating on the skin-layer of the molded polymer were observed by using a mold with transparent windows, and the residual birefringence frozen in the final molded specimen was measured. The results clearly showed that the birefringence in the skin-layer of injection molded polymer strips was reduced with CO{sub 2} laser heating. The authors believe that the proposed method for reducing the birefringence frozen in injection-molded polymer products is suitable for practical molding, because process time required for the injection-molding is only slightly increased with this method.

  15. Influence of static and dynamic bends on the birefringence decay profile of RNA helices: Brownian dynamics simulations.

    PubMed Central

    Zacharias, M; Hagerman, P J

    1997-01-01

    Bends in nucleic acid helices can be quantified in a transient electric birefringence (TEB) experiment from the ratio of the terminal decay times of the bent molecule and its fully duplex counterpart (tau-ratio method). The apparent bend angles can be extracted from the experimental tau-ratios through the application of static (equilibrium-ensemble) hydrodynamic models; however, such models do not properly address the faster component(s) of the birefringence decay profile, which can represent up to 80% of the total birefringence signal for large band angles. To address this latter issue, the relative amplitudes of the components in the birefringence decay profile have been analyzed through a series of Brownian dynamics (BD) simulations. Decay profiles have been simulated for three-, five-, and nine-bead models representing RNA molecules with central bends of 30 degrees, 60 degrees, and 90 degrees, and with various degrees of associated angle dispersion. The BD simulations are in close agreement with experimental results for the fractional amplitudes, suggesting that both amplitudes and terminal tau-ratios can be used as a measure of the magnitudes of bends in the helix axis. Although the current results indicate that it is generally not possible to distinguish between relatively fixed and highly flexible bends from single tau-ratio measurements, because they can lead to similar reductions in terminal decay time and amplitude, measurements of the dependence of the fractional amplitudes on helix length may afford such a distinction. PMID:9199796

  16. Deep tissue volume imaging of birefringence through fibre-optic needle probes for the delineation of breast tumour

    PubMed Central

    Villiger, Martin; Lorenser, Dirk; McLaughlin, Robert A.; Quirk, Bryden C.; Kirk, Rodney W.; Bouma, Brett E.; Sampson, David D.

    2016-01-01

    Identifying tumour margins during breast-conserving surgeries is a persistent challenge. We have previously developed miniature needle probes that could enable intraoperative volume imaging with optical coherence tomography. In many situations, however, scattering contrast alone is insufficient to clearly identify and delineate malignant regions. Additional polarization-sensitive measurements provide the means to assess birefringence, which is elevated in oriented collagen fibres and may offer an intrinsic biomarker to differentiate tumour from benign tissue. Here, we performed polarization-sensitive optical coherence tomography through miniature imaging needles and developed an algorithm to efficiently reconstruct images of the depth-resolved tissue birefringence free of artefacts. First ex vivo imaging of breast tumour samples revealed excellent contrast between lowly birefringent malignant regions, and stromal tissue, which is rich in oriented collagen and exhibits higher birefringence, as confirmed with co-located histology. The ability to clearly differentiate between tumour and uninvolved stroma based on intrinsic contrast could prove decisive for the intraoperative assessment of tumour margins. PMID:27364229

  17. Growth and birefringence studies of semi organic non-linear optical LHB single crystal

    NASA Astrophysics Data System (ADS)

    Jayaramakrishnan, V.; Prasanyaa, T.; Haris, M.; Bhoopathi, G.

    2015-02-01

    In the last few decades nonlinear optical materials are getting attention in the field of optical data storage, telecommunication, second harmonic generation (SHG) and optical signal processing, etc. In the present work we are reporting the single crystal growth of L-Histidine with hydro-bromic acid. The L-Histidine bromide (LHB) single crystals have been harvested from the solution in a span of 34 days by adopting slow cooling solution growth technique. The grown crystals have been subjected to powder X-ray diffraction studies to identify the cell parameters and structure. The crystalline perfection has been defined by rocking curve (HRXRD) analysis. Optical transmission spectra reveal the optical properties of the grown crystals. The Modified channel spectrum (MCS) method has been adopted for the study of spectral dependence of linear birefringence over the wavelength range 480-620 nm. The second harmonic generation efficiency was tested by using Kurtz and Perry method, keeping KDP as reference.

  18. {sup 3}He polarization via optical pumping in a birefringent cell

    SciTech Connect

    Masuda, Y.; Ino, T.; Skoy, V.R.; Jones, G.L.

    2005-08-01

    A sapphire cell was used to obtain a high {sup 3}He nuclear polarization by means of spin-exchange optical pumping. The phase-shift difference between ordinary and extraordinary rays is well controlled using the thickness of the birefringent sapphire window so that a high circular polarization is obtained in the cell. Neutron transmission through the polarized {sup 3}He gas was measured as a function of neutron energy. A large {sup 3}He polarization of 63{+-}1% was obtained at a {sup 3}He pressure of 3.1 atm. Neutron polarizations of 97 and 90 % were obtained with transmission rates of 15 and 22 % at 10 and 20 meV, respectively.

  19. Negative Birefringence in the Higher Homologs of the 5O.m Series of Liquid Crystals.

    PubMed

    Bhattacharjee, Debanjan; Alapati, Parameswara Rao; Bhattacharjee, Ayon

    2016-07-14

    A detailed study of the different parameters of the higher homologs of the 5O.m (m = 14, 16) series of liquid-crystalline compounds is reported. These are interdigitated compounds with unsymmetrical alkyl chain length. The compounds have a unique nature, unlike the other members of the nO.m series. The molecular structure reported in this article is not purely uniaxial; it has a bending tendency. In this article, we report that both the compounds exhibit negative birefringence. For the optical study, the refractive indices, ne and no, of the sample are measured by the thin-prism technique, using a He-Ne laser beam of wavelength 633 nm. A four-parameter model was used for fitting the experimental results. From the experimentally measured refractive indices, it is possible to compare different parameters with those of the theoretical models. PMID:27267484

  20. Anisotropic hybrid organic/inorganic (azopolymer/SiO2 NP) materials with enhanced photoinduced birefringence.

    PubMed

    Nazarova, Dimana; Nedelchev, Lian; Sharlandjiev, Peter; Dragostinova, Violeta

    2013-08-01

    Hybrid materials based on combination of polymers and inorganic nanoparticles (NP) attracted considerable attention in the last decade due to their advantageous electrical, optical, or mechanical properties. Recently, we reported a significant improvement of the photoresponse by doping azopolymers with ZnO NP. To study the influence of the composition of the dopant, in our present work we have synthesized anisotropic organic/inorganic nanocomposite materials by incorporating 5-15 nm sized SiO2 NP in a side-chain azopolymer. As a result we observe an enhancement of the photoinduced birefringence in these composite materials with about 20% compared to the nondoped sample. Additionally, we discuss possible mechanisms leading to this enhancement related with the scattering caused by the NP and the increased mobility of the azochromophores in the vicinity of NP. PMID:23913084

  1. Effect of uniaxial stress on the birefringence of triglycine sulphate crystals doped with L threonine

    NASA Astrophysics Data System (ADS)

    Stadnyk, V. Yo.; Kiryk, Yu. I.

    2012-05-01

    The temperature and spectral dependences of the birefringence Δ n i of triglycine sulphate (TGS) crystals with L-threonine impurity have been investigated. Doping with L-threonine is found to reduce the temperature dependence of Δ n i of TGS crystals. The baric coefficients of shift of the phase-transition (PT) point, ∂ T c /∂σ m, are found to be somewhat smaller than those for pure TGS crystals, which is confirmed by the increase in the hardness of TGS crystals after doping. The temperature and spectral dependences of the combined piezoelectric constants π{/im 0} have been calculated. The stepwise changes in all piezoelectric constants at the PT of doped crystals are found to be much smaller than those for pure crystals.

  2. High-birefringence fiber loop mirror sensor using a WDM fused fiber coupler.

    PubMed

    Passos, D J; Marques, Manuel J; Frazão, Orlando

    2013-08-01

    An intensity-based highly birefringent (Hi-Bi) fiber loop mirror (FLM) sensor is proposed which uses a wavelength-division multiplexing (WDM) fiber coupler. The effect of integrating the WDM coupler in a FLM configuration is first studied. A section of Hi-Bi (bow-tie) fiber of length 0.26 m is then placed in the fiber loop, making the spectral response of the device simultaneously dependent on the Hi-Bi fiber section and WDM coupler characteristics. When strain is applied to the sensing head, the spectral signal is modulated in amplitude, in contrast with the conventional Hi-Bi FLM sensors in which there are wavelength shifts. The sensor was characterized in strain and a sensitivity of (-2.2±0.4)×10(-3) με(-1) for a range of 300 με was attained. The self-referenced character of the sensor is noted. PMID:23903181

  3. Application of Brillouin scattering to the local anisotropy and birefringence measurements of thin layers.

    PubMed

    Matsukawa, Mami; Shintani, Kazuaki; Tomohiro, Shin-ichi; Ohtori, Norikazu

    2006-12-22

    Brillouin scattering is an efficient nondestructive and noncontact measurement method to obtain the wave properties of thin layers at hypersonic frequencies. The reflection induced ThetaA (RIThetaA) scattering geometry enables the simultaneous measurement of the phonons, which propagate in each direction of wave vectors of q(Theta A) (propagation in the film plane) and q(180) (back scattering). Using this scattering geometry, we could observe the refractive indices and birefringence of the piezoelectric poly-vinylidene fluoride (PVDF) film as a function of temperature. By introducing the microscopic technique, the elastic anisotropy and refractive index measurements in the minute area of polycrystalline ZnO films were also performed. PMID:16814836

  4. Scanning Fourier transform spectrometer in the visible range based on birefringent wedges.

    PubMed

    Oriana, Aurelio; Réhault, Julien; Preda, Fabrizio; Polli, Dario; Cerullo, Giulio

    2016-07-01

    We introduce a spectrometer capable of measuring sample absorption spectra in the visible regime, based on a time-domain scanning Fourier transform (FT) approach. While infrared FT spectrometers typically employ a Michelson interferometer to create the two delayed light replicas, the proposed apparatus exploits a compact common-mode passive interferometer that relies on the use of birefringent wedges. This ensures excellent path-length stability (∼λ/300) and accuracy, with no need for active feedback or beam tracking. We demonstrate the robustness of the technique measuring the transmission spectrum of a colored bandpass filter over one octave of bandwidth and compare the results with those obtained with a commercial spectrophotometer. PMID:27409701

  5. Theoretical simulation of a novel birefringent photonic crystal fiber with surface plasmon resonance around 1300 nm

    NASA Astrophysics Data System (ADS)

    Duanming, Li; Guiyao, Zhou

    2016-03-01

    In this paper, a novel birefringent photonic crystal fiber (PCF) with the silver-coated and liquid-filled air-holes along the vertical plane is designed. Simulation results show that the thickness of silver layer, the sizes of holes, and the refractive index of liquid strongly strengthen the gaps between two polarized directions. The surface plasmon resonance peak along y axis can be up to 675.8 dB/cm at 1.33 μm. The proposed PCF has important application in polarization devices, such as filters and beam splitters. Project partly supported by the National Basic Research Development Program of China (Grant No. 2010CB327604), the National Natural Science Foundation of China (Grant No. 61377100), and the Natural Science Foundation of Guangdong Province, China (Grant No. S2013040015665).

  6. LIMITS ON COSMOLOGICAL BIREFRINGENCE FROM THE ULTRAVIOLET POLARIZATION OF DISTANT RADIO GALAXIES

    SciTech Connect

    Alighieri, Sperello di Serego; Finelli, Fabio; Galaverni, Matteo

    2010-05-20

    We report on an update of the test on the rotation of the plane of linear polarization for light traveling over cosmological distances, using a comparison between the measured direction of the UV polarization in eight radio galaxies at z>2 and the direction predicted by the model of scattering of anisotropic nuclear radiation, which explains the polarization. No rotation is detected within a few degrees for each galaxy and, if the rotation does not depend on direction, then the all-sky-average rotation is constrained to be {theta} = -0.{sup 0}8 {+-} 2.{sup 0}2. We discuss the relevance of this result for constraining cosmological birefringence when this is caused by the interaction with a cosmological pseudo-scalar field or by the presence of a Cherns-Simons term.

  7. A quantitative collagen fibers orientation assessment using birefringence measurements: calibration and application to human osteons.

    PubMed

    Spiesz, Ewa M; Kaminsky, Werner; Zysset, Philippe K

    2011-12-01

    Even though mechanical properties depend strongly on the arrangement of collagen fibers in mineralized tissues, it is not yet well resolved. Only a few semi-quantitative evaluations of the fiber arrangement in bone, like spectroscopic techniques or circularly polarized light microscopy methods are available. In this study the out-of-plane collagen arrangement angle was calibrated to the linear birefringence of a longitudinally fibered mineralized turkey leg tendon cut at variety of angles to the main axis. The calibration curve was applied to human cortical bone osteons to quantify the out-of-plane collagen fibers arrangement. The proposed calibration curve is normalized to sample thickness and wavelength of the probing light to enable a universally applicable quantitative assessment. This approach may improve our understanding of the fibrillar structure of bone and its implications on mechanical properties. PMID:21970947

  8. Mueller-matrices polarization selection of two-dimensional linear and circular birefringence images

    NASA Astrophysics Data System (ADS)

    Ushenko, V. A.; Zabolotna, N. I.; Pavlov, S. V.; Burcovets, D. M.; Novakovska, O. Yu.

    2013-12-01

    The work consists of investigation results of diagnostic efficiency of a new azimuthally stable Mueller-matrix method of analysis of laser autofluorescence coordinate distributions of biological tissues histological sections. A new model of generalized optical anisotropy of biological tissues protein networks is proposed in order to define the processes of laser autofluorescence. The influence of complex mechanisms of both phase anisotropy (linear birefringence and optical activity) and linear (circular) dichroism is taken into account. The interconnections between the azimuthally stable Mueller-matrix elements characterizing laser autofluorescence and different mechanisms of optical anisotropy are determined. The complex statistic, correlation and fractal analysis of coordinate distributions of such Mueller-matrix rotation invariants is proposed. Thereupon the quantitative criteria (statistic moments of the 1st to the 4th order, correlation moment, fratal parameters) of differentiation of histological sections of uterus wall tumor - group 1 (polypus) and group 2 (adenocarcinoma) are estimated.

  9. Investigating the permanent electric dipole moment of beta-lactoglobulin fibrils, using transient electric birefringence.

    PubMed

    Rogers, S S; Venema, P; van der Ploeg, J P M; van der Linden, E; Sagis, L M C; Donald, A M

    2006-06-15

    Amyloid fibrils, which are polymeric assemblies of protein molecules, have been intensively studied on a structural level, yet due to complications such as the disorder within the molecules, several aspects of their structure remain mysterious. Similarly, the kinetics of assembly are not well understood. Here we investigate the electric dipole moment of beta-lactoglobulin fibrils, a model amyloid fibril system, by applying the technique of transient electric birefringence. This moment appears to be large, and comparable to the total moment of the constituent protein monomers if they were joined in a chain, head-to-tail, without changing conformation, suggesting an ordered joining of monomers in the fibril. Such an ordered assembly may have implications for the assembly mechanism of beta-lactoglobulin fibrils in particular, and amyloid fibrils in general. PMID:16489587

  10. Microstructured low and high birefringence four core fibers for sensing applications

    NASA Astrophysics Data System (ADS)

    Wójcik, Jan; Makara, Mariusz; Mergo, Paweł; Janoszczyk, Barbara; Klimek, Jacek

    2006-04-01

    Optical fiber strain or bend sensors have been demonstrated for complex monitoring various structures especially in aerospace, marine civil engineering and especially in optical security systems. Optical fiber sensors based on Fabry-Perot interferometers and fiber Bragg gratings are useful for point or slow-multiplied sensor systems. Distributed optical fiber system based on Sagnac interferometers used of low or high-birefringence optical fibers as strain/bend sensing elements. Special optical fibers as four core single mode fibers in Mach-Zehnder interferometer system have been used. In all described cases the high influence of temperature on sensor characteristics is very important disadvantage at measurement systems. In this paper we describe fabrication and characterization of the new four core PCF index guided fiber designed for interferometric bend measurements.

  11. 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.

  12. Techniques for Fast and Sensitive Measurements of Two-Dimensional Birefringence Distributions

    NASA Astrophysics Data System (ADS)

    Shribak, Michael; Oldenbourg, Rudolf

    2003-06-01

    We propose image processing algorithms for measuring two-dimensional distributions of linear birefringence using a pair of variable retarders. Several algorithms that use between two and five recorded frames allow us to optimize measurements for speed, sensitivity, and accuracy. We show images of asters, which consist of radial arrays of microtubule polymers recorded with a polarized light microscope equipped with a universal compensator. Our experimental results confirm our theoretical expectations. The lowest noise level of 0.036 nm was obtained when we used the five-frame technique and four-frame algorithm without extinction setting. The two-frame technique allows us to increase the speed of measurement with acceptable image quality.

  13. Polarization-maintaining, double-clad fiber amplifier employing externally applied stress-induced birefringence

    SciTech Connect

    Koplow, Jeffrey P.; Goldberg, Lew; Moeller, Robert P.; Kliner, Dahv A. V.

    2000-03-15

    We report a new approach to obtaining linear-polarization operation of a rare-earth-doped fiber amplifier in which the gain fiber is coiled under tension to induce birefringence. We demonstrated this method by constructing an Er/Yb-doped, double-clad, single-mode fiber amplifier with an output power of 530 mW and a polarization extinction ratio of >17 dB (when seeded with linearly polarized light) at a wavelength of {approx}1.5 {mu}m . The technique is achromatic, permits single- or multiple-pass operation of the amplifier, requires no additional components in the optical path, leaves the fiber ends unobstructed, and is inexpensive to implement. (c) 2000 Optical Society of America.

  14. Field-Effect Birefringent Spin Lens in Ultrathin Film of Magnetically Doped Topological Insulators

    NASA Astrophysics Data System (ADS)

    Zhao, Lu; Tang, Peizhe; Gu, Bing-Lin; Duan, Wenhui

    2013-09-01

    We investigate the low-energy electron dynamics in two-dimensional ultrathin film of magnetically doped topological insulators in the context of gate-tuned coherent spin manipulation. Our first-principles calculations for such film unambiguously identify its spin-resolved topological band structure arising from spin-orbit coupling and time-reversal symmetry breaking. Exploiting this characteristic, we predict a negative birefraction for chiral electron tunneling through a gate-controlled p-n interface in the film, analogous to optical birefringence. By fine-tuning the gate voltage, a series of unusual phenomena, including electron double focusing, spatial modulation of spin polarizations, and quantum-interference-induced beating patterns, could be efficiently implemented, offering a powerful platform to establish spin-resolved electron optics by all-electrical means.

  15. Polarization effects in birefringent fiber-optic waveguides with an elliptical borosilicate cladding

    NASA Astrophysics Data System (ADS)

    Grigoriants, V. V.; Zalogin, A. N.; Ivanov, G. A.; Isaev, V. A.; Kozel, S. M.

    1986-10-01

    Single-mode fiber-optic waveguides (SFW) with an elliptical borosilicate cladding are developed and their polarization characteristics are studied. It is shown that their mode birefringence, while independent of the radiation frequency, depends linearly on the SFW temperature. The beat length is about 10 mm at a wavelength of 0.85 micron and the dispersion of the polarization modes is about 300 ps/km. The losses amount to 5-10 dB/km at 0.85 micron and the mode coupling parameter is 0.0002/m. Consideration is given to the possibility of using SFW for the depolarization of nonmonochromatic radiation and as tunable delay lines.

  16. Interrogation cradle and insertable containment fixture for detecting birefringent microcrystals in bile

    DOEpatents

    Darrow, Chris; Seger, Tino

    2003-09-30

    A transparent flow channel fluidly communicates a fluid source and a collection reservoir. An interrogating light beam passes through a first polarizer having a first plane of polarization. The flow channel is orthogonal to the light beam. The light beam passes through a fluid sample as it flows through the flow channel, and is then filtered through a second polarizer having a second plane of polarization rotated 90.degree. from the first plane of polarization. An electronic photo-detector is aligned with the light beam, and signals the presence of birefringent microcrystals in the fluid sample by generating voltage pulses. A disposable containment fixture includes the flow channel and the collection reservoir. The fixture is adapted for removable insertion into an interrogation cradle that includes optical and data processing components. The cradle rigidly positions the centerline of the flow channel orthogonal to the light beam.

  17. Measurement of residual birefringence in thin glass plates using digital photoelasticity

    NASA Astrophysics Data System (ADS)

    Tarkes Dora, P.; Ramesh, K.

    2014-06-01

    Residual stresses in glass causes it birefringent, affecting its optical properties. Annealed P-LASF47%trade; glass plates of 75 × 20 × 5 mm are subjected to two different thermal cycles. An automatic polariscope is used to employ Phase Shifting Technique (PST) to determine the residual integrated retardations over the thickness. Smaller field of view of the polariscope necessitates analysing the glass plate separately for the upper and lower regions of the glass plate. A code is developed in MATLAB to stitch the retardation data for the upper and lower region. The integrated retardation for the whole field is plotted as a contour plot using OriginPro software. Maximum retardation is observed in small regions at the free surfaces of the glass plate. It is noted that the nature of the thermal cycle has an influence on the retardation distribution.

  18. Concurrent measurement of linear and circular birefringence using rotating-wave-plate Stokes polarimeter.

    PubMed

    Lin, Jing-Fung

    2008-09-01

    A novel technique is presented for obtaining concurrent measurements of the linear and circular birefringence properties of an optical sample by using a rotating-wave-plate Stokes polarimeter to extract the 2x2 central elements of the corresponding Mueller matrix via two linearly polarized probe lights. For a compound sample comprising a half-wave plate in series with a quarter-wave plate, the measured values of the principal angle and retardance of the quarter-wave plate are found to have average normalized errors of 0.56% and 1.16%, respectively, while the measured value of the rotation angle of the half-wave plate has an error of just 0.39%. When analyzing glucose solutions with concentrations ranging from 0-1.2 g/dl positioned in front of a half-wave plate, the average normalized errors in the principal axis angle and retardance measurements of the half-wave plate are 0.69% and 2.65%, respectively, while the error in the rotation angle measurements of the glucose solutions is 2.13%. The correlation coefficient between the measured rotation angle and the concentration of the glucose solution is determined to be 0.99985, while the standard deviation is just 0.0022 deg. Overall the experimental results demonstrate the ability of the proposed system to obtain highly accurate measurements of the linear and circular birefringence properties of an optical sample and to decouple the relationship between the principal axis angle and the rotation angle. PMID:18758522

  19. Determination of optical birefringence of S-benzylisothiouronium chloride and S-benzylisothiouronium nitrate using Cauchy’s two term model by the channelled spectrum method

    NASA Astrophysics Data System (ADS)

    Hemalatha, P.; Veeravazhuthi, V.; Shashidharan Nair, C. K.

    2009-07-01

    The channelled spectrum method was used for measuring the birefringence of anisotropic organic single crystals S-benzylisothiouronium chloride (SBTC) and S-benzylisothiouronium nitrate (SBTN). Crystals of uniform thickness were placed between crossed polarizers and illuminated with a tungsten source. The resulting pattern was analyzed to deduce the birefringence and its dispersion across the visible spectrum. Cauchy's two term formula was applied to fit the experimental data. The Cauchy's coefficients A and B were obtained by solving the linear equations using MATLAB ®. The wavelength dispersion of birefringence was calculated.

  20. High birefringent rectangular-lattice photonic crystal fibers with low confinement loss employing different sizes of elliptical air holes in the cladding and the core

    NASA Astrophysics Data System (ADS)

    Liao, Jianfei; Sun, Junqiang

    2012-12-01

    Based on the full-vector finite element method with anisotropic perfectly matched layers, modal birefringence and confinement loss for the fundamental mode in rectangular-lattice photonic crystal fibers with different sizes of elliptical air holes in the cladding and the core are investigated numerically. The results show that the modal birefringence in this proposed photonic crystal fibers can be up to 5.64 × 10-2 at the wavelength of 1.55 μm. Moreover, when the birefringence is higher than 4 × 10-2, the confinement loss of x-polarized mode can be kept less than 0.005 dB/km at 1.55 μm. It means that the tradeoff between the high birefringence and the low confinement loss is overcome.

  1. Electric-field-induced linear birefringence in TmAl3(BO3)4.

    PubMed

    Pashchenko, M I; Bedarev, V A; Merenkov, D N; Gnatchenko, S L; Bezmaternykh, L N; Sukhachev, A L; Temerov, V L

    2016-04-20

    The linear birefringence induced by the electric field was first detected in a TmAl3(BO3)4 single crystal. The electric field dependence of the birefringence was investigated. The estimation of the electro-optical coefficient of the material gives ≈1.5×10-10  cm/V for a wavelength 632.8 nm. PMID:27140114

  2. Laser-induced radial birefringence and spin-to-orbital optical angular momentum conversion in silver-doped glasses

    SciTech Connect

    Amjad, Jafar Mostafavi; Khalesifard, Hamid Reza; Slussarenko, Sergei; Karimi, Ebrahim; Santamato, Enrico; Marrucci, Lorenzo

    2011-07-04

    Samples of Ag{sup +}/Na{sup +} ion-exchanged glass that have been subject to intense laser irradiation may develop novel optical properties, as a consequence of the formation of patterns of silver nanoparticles and other structures. Here, we report the observation of a laser-induced permanent transverse birefringence, with the optical axis forming a radial pattern, as revealed by the spin-to-orbital angular momentum conversion occurring in a probe light beam. The birefringence pattern can be modeled well as resulting from thermally-induced stresses arising in the silver-doped glass during laser exposure, although the actual mechanism leading to the permanent anisotropy is probably more complex.

  3. Novel force sensor based on a high-birefringence fiber loop mirror and a freely supported beam

    NASA Astrophysics Data System (ADS)

    Li, Shuhong; Zhao, Qida; Bo, Dong; Liao, Tongqing; Miao, Yinping; Zeng, Xiangye

    2007-11-01

    A novel high-birefringence fiber loop mirror(HBFLM) force sensor based on a freely supported beam(FSB) is demonstrated theoretically and experimentally. Part of the high-birefringence fiber(HBF) is pasted onto the central surface of the FSB. The force is applied to the center of the FSB, which leads to the pre-demarcated wavelength shift of the transmission spectrum of the HBFLM. The sensitivity reaches 8.9N/nm, the resolution is 0.049N, and the linear measurement range is 0.049N~0.392N.There is a good linear relationship between the force and the wavelength shift. The advantages of the sensor include simple structure, high sensitivity, low cost, and good repeatability, etc.

  4. Orientational dynamics of ferrofluids with finite magnetic anisotropy of the particles: relaxation of magneto-birefringence in crossed fields.

    PubMed

    Raikher, Yu L; Stepanov, V I; Bacri, J-C; Perzynski, R

    2002-08-01

    Dynamic birefringence in a ferrofluid subjected to crossed bias (constant) and probing (pulse or ac) fields is considered, assuming that the nanoparticles have finite magnetic anisotropy. This is done on the basis of the general Fokker-Planck equation that takes into account both internal magnetic and external mechanical degrees of freedom of the particle. We describe the orientation dynamics in terms of the integral relaxation time of the macroscopic orientation order parameter. To account for an arbitrary relation between the bias (external) and anisotropy (internal) fields, an interpolation expression for the integral relaxation time is proposed and justified. A developed description is used to interpret the measurements of birefringence relaxation in magnetic fluids with nanoparticles of high (cobalt ferrite) and low (maghemite) anisotropy. The proposed theory appears to be in full qualitative agreement with all the experimental data available. PMID:12241160

  5. Domain switching emission from the mixed-mode crack in ferroelectrics by birefringence measurement and phase field modeling

    NASA Astrophysics Data System (ADS)

    Li, Qun; Pan, Suxin; Liu, Qida; Wang, Jie

    2016-07-01

    The spatial and temporal evolution of domain switching near the tip of a mixed-mode crack (e.g., an inclined crack) is observed in ferroelectrics. The birefringence technique is used to measure the optical quantities to demonstrate the domain switching near the crack tip. The results show an intriguing feature that there appears electrical creep and domain switching emission from the crack tip. The actual time-dependence of domain switching emission and its anisotropic velocity is approximately measured. Moreover, the phase field modeling is developed to simulate polarization distribution and domain switching near the crack tip where the time-dependent Ginzburg–Landau equation is used to describe the change of polarization. The phase field results indicate the same features of domain switching emission from the mixed-mode crack. A good agreement between phase field simulation and birefringence measurement is concluded by setting the appropriate kinetic coefficient in the time-dependent Ginzburg–Landau equation.

  6. Design of hybrid photonic crystal fiber with elliptical and circular air holes analyzed for large flattened dispersion and high birefringence

    NASA Astrophysics Data System (ADS)

    Sharma, Varshali; Sharma, Ritu

    2016-04-01

    A design of two-dimensional hybrid photonic crystal fiber (PCF) with elliptical and circular air holes and its analyses for large flattened dispersion and high birefringence is presented. The PCF has hexagonal layout with triangular lattice. There are five rings around the solid core. The inner three rings around the core have elliptical air holes while the outer two rings have circular air holes. Three such layouts are designed, analyzed, and compared with the layout having only circular air hole using full-vector finite difference time domain method. The layout with hybrid structure having combined elliptical and circular air hole gives a large flattened dispersion of the order of 4.88 ps/nm/km for the wavelength range of 1.2 to 1.8 μm and magnitude of modal birefringence is 1.238×10-3 at 1.55-μm wavelength.

  7. Superior electro-optical properties of electrically controlled birefringence mode using solution-derived La{sub 2}O{sub 3} films

    SciTech Connect

    Jeong, Hae-Chang; Park, Hong-Gyu; Lee, Ju Hwan; Seo, Dae-Shik; Oh, Byeong-Yun

    2015-11-15

    The authors demonstrate a high performance electrically controlled birefringence (ECB) mode with solution-derived La{sub 2}O{sub 3} films at various molar concentrations. Uniform and homogeneous liquid crystal (LC) alignment was spontaneously achieved on the La{sub 2}O{sub 3} films for lanthanum concentrations at ratios greater than and equal to 0.2. A preferred orientation of LC molecules appeared along the filling direction, and the LC alignment was maintained via van der Waals force by nanocrystals of the La{sub 2}O{sub 3} films. The LC alignment mechanism was confirmed by x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis. Superior electro-optical characteristics of the ECB cells constructed with solution-derived La{sub 2}O{sub 3} films were observed, which suggests that the proposed solution-derived La{sub 2}O{sub 3} films have strong potential for use in the production of advanced LC displays.

  8. Structural circular birefringence and dichroism quantified by differential decomposition of spectroscopic transmission Mueller matrices from Cetonia aurata.

    PubMed

    Arwin, H; Mendoza-Galván, A; Magnusson, R; Andersson, A; Landin, J; Järrendahl, K; Garcia-Caurel, E; Ossikovski, R

    2016-07-15

    Transmission Mueller-matrix spectroscopic ellipsometry is applied to the cuticle of the beetle Cetonia aurata in the spectral range 300-1000 nm. The cuticle is optically reciprocal and exhibits circular Bragg filter features for green light. By using differential decomposition of the Mueller matrix, the circular and linear birefringence as well as dichroism of the beetle cuticle are quantified. A maximum value of structural optical activity of 560°/mm is found. PMID:27420518

  9. Modification of birefringence properties of nanostructured silicon with a change in the level of substrate doping with boron

    SciTech Connect

    Piskunov, N. A. Zabotnov, S. V.; Mamichev, D. A.; Golovan', L. A.; Timoshenko, V. Yu.; Kashkarov, P. K.

    2007-07-15

    Birefringence of porous-silicon films prepared by electrochemical etching of boron-doped Si(110) wafers with a resistivity of 25-45 m{theta} cm has been studied. The samples are found to exhibit the properties of a negative uniaxial crystal with the optical axis oriented along the [11-bar0] crystallographic direction. The possibility of using porous-silicon films as phase plates for light-polarization control in the near and mid-IR ranges is demonstrated.

  10. Influence of the strength of polarizing electric field on free relaxation of electric birefringence in poly(butyl-isocyanate) solutions

    NASA Astrophysics Data System (ADS)

    Tsvetkov, N. V.; Mikhailova, M. E.; Lebedeva, E. V.; Lezov, A. A.; Rogozhin, V. B.; Rotinyan, T. A.

    2016-03-01

    Free relaxation of electric birefringence in tetrachloromethane solution of high molecular weight poly(butyl-isocyanate) was studied. The effect of electric field strength on the average relaxation time was observed. The relaxation spectrum was analyzed using the Rouse and Zimm theories. With increase in the electric field strength, the contribution of fast (deformation) relaxation modes also increased significantly. It is assumed that certain changes in intramolecular mobility occur under the influence of electric field.

  11. Soliton Pulse Compression in a Dispersion Decreasing Elliptic Birefringent Fiber with Effective Gain and Effective Phase Modulation

    NASA Astrophysics Data System (ADS)

    Ganapathy, R.; Kuriakose, V. C.

    We have considered soliton pulse compression in a dispersion decreasing ideal elliptical birefringent fiber with phase modulation. We have shown that there is exact balancing between the effective gain and the effective phase modulation and as a result arrive at the fundamental soliton solution. For the various dispersion decreasing profiles we have considered, we have shown that the hyperbolic profile is the best suitable choice for the dispersion decreasing profile as it provides fairly good compression even after compensating for the fiber loss.

  12. A universal compensator for polarization changes induced by non-reciprocal circular birefringence on a retracing beam

    NASA Astrophysics Data System (ADS)

    Martinelli, Mario; Martelli, Paolo; Fasiello, Annalaura

    2016-05-01

    In this communication we recognize that it is possible to cancel out the effects of the non-reciprocal circular birefringence on a retracing beam. The experimental results demonstrate that a linearly polarized beam is returned into an orthogonal state after retracing through a variable Faraday rotator, by exploiting the reflective action of a Porro prism with edge at 45° with respect to the initial polarization axis, for any amount of non-reciprocal Faraday rotation.

  13. Crystal structure of a birefringent andradite-grossular from Crowsnest Pass, Alberta, Canada

    SciTech Connect

    Antao, Sytle M.; Klincker, Allison M.

    2014-02-20

    The structure of a birefringent andradite–grossular sample was refined using single-crystal X-ray diffraction (SCD) and synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Electron-microprobe results indicate a homogeneous composition of {Ca2.88Mn2+ 0.06Mg0.04Fe2+ 0.03}Σ3[Fe3+ 1.29Al0.49Ti4+ 0.17Fe2+ 0.06] Σ2(Si2.89Al0.11) Σ3O12. The Rietveld refinement reduced χ2 = 1.384 and overall R (F2) = 0.0315. The HRPXRD data show that the sample contains three phases. For phase-1, the weight %, unit-cell parameter (Å), distances (Å), and site occupancy factor (sof) are 62.85(7)%, a = 12.000 06(2), average = 2.4196, Fe–O = 1.9882(5), Si–O = 1.6542(6) Å, Ca(sof) = 0.970(2), Fe(sof) = 0.763(1), and Si(sof) = 0.954(2). The corresponding data for phase-2 are 19.14(9)%, a = 12.049 51(2), average = 2.427, Fe–O = 1.999(1), Si–O = 1.665(1) Å, Ca(sof) = 0.928(4), Fe(sof) = 0.825(3), and Si(sof) = 0.964(4). The corresponding data for phase-3 are 18.01(9)%, a = 12.019 68(3), average = 2.424, Fe–O = 1.992(2), Si–O = 1.658(2) Å, Ca(sof) = 0.896(5), Fe(sof) = 0.754(4), and Si(sof) = 0.936(5). The fine-scale coexistence of the three phases causes strain that arises from the unit-cell and bond distances differences, and gives rise to strain-induced birefringence. The results from the SCD are similar to the dominant phase-1 obtained by the HRPXRD, but the SCD misses the minor phases.

  14. Immunoassays for the cancer biomarker CA125 based on a large-birefringence nematic liquid-crystal mixture.

    PubMed

    Sun, Shih-Hung; Lee, Mon-Juan; Lee, Yun-Han; Lee, Wei; Song, Xiaolong; Chen, Chao-Yuan

    2015-01-01

    The use of fluorescence is ubiquitously found in the detection of immunoreaction; though with good sensitivity, this technique requires labeling as well as other time-consuming steps to perform the measurement. An alternative approach involving liquid crystals (LCs) was proposed, based on the fact that an immunocomplex can disturb the orientation of LCs, leading to an optical texture different from the case when only antigen or antibody exists. This method is label-free, easy to manipulate and low-cost. However, its sensitivity was low for practical usage. In this study, we adopted a high-birefringence liquid crystal (LC) to enhance the sensitivity for the immunodetection. Experiments were performed, targeting at the cancer biomarker CA125. We showed that the larger birefringence (Δn = 0.33 at 20 °C) amplifies the detected signal and, in turn, dramatically improves the detection limit. To avoid signal loss from conventional rinsing steps in immunodetection, CA125 antigen and antibody were reacted before immobilized on substrates. We studied the specific binding events and obtained a detection limit as low as 1 ng/ml. The valid temperature ranges were compared by using the typical single-compound LC 5CB and the high-birefringence LC mixture. We further investigated time dependency of the optical textures and affirmed the capability of LC-based immunodetection in distinguishing between specific and nonspecific antibodies. PMID:25657889

  15. Distributed phase birefringence measurements based on polarization correlation in phase-sensitive optical time-domain reflectometers.

    PubMed

    Soto, Marcelo A; Lu, Xin; Martins, Hugo F; Gonzalez-Herraez, Miguel; Thévenaz, Luc

    2015-09-21

    In this paper a technique to measure the distributed birefringence profile along optical fibers is proposed and experimentally validated. The method is based on the spectral correlation between two sets of orthogonally-polarized measurements acquired using a phase-sensitive optical time-domain reflectometer (ϕOTDR). The correlation between the two measured spectra gives a resonance (correlation) peak at a frequency detuning that is proportional to the local refractive index difference between the two orthogonal polarization axes of the fiber. In this way the method enables local phase birefringence measurements at any position along optical fibers, so that any longitudinal fluctuation can be precisely evaluated with metric spatial resolution. The method has been experimentally validated by measuring fibers with low and high birefringence, such as standard single-mode fibers as well as conventional polarization-maintaining fibers. The technique has potential applications in the characterization of optical fibers for telecommunications as well as in distributed optical fiber sensing. PMID:26406692

  16. The influence of the fiber drawing process on intrinsic stress and the resulting birefringence optimization of PM fibers

    NASA Astrophysics Data System (ADS)

    Just, Florian; Spittel, Ron; Bierlich, Jörg; Grimm, Stephan; Jäger, Matthias; Bartelt, Hartmut

    2015-04-01

    The propagation properties of optical fibers can be significantly influenced by intrinsic stress. These effects are often undesired but in some cases essential for certain applications, e.g. in polarization maintaining (PM) fibers. In this paper, we present systematic studies on the influence of the fiber drawing process on the generated stress and demonstrate an approach to significantly increase the stress induced birefringence of PM-fibers. It is shown that the thermal stress caused by the material composition is superimposed with the mechanical stress caused by the fiber fabrication process. This intrinsic stress has a strong effect on the optical and mechanical properties of the glass and thus influences the fiber stability and modal behavior. By applying a thermal annealing step, the mechanical stress due to the fiber drawing process can be canceled. It is shown that this annealing step compensates the stress reducing influence of the drawing process on the birefringence of PM-fibers with panda structure. The comparison of the intrinsic stress states after fabrication with the state after the additional high temperature annealing step clearly shows that it is possible to improve the overall birefringence of panda fibers using appropriate preparation steps.

  17. Exploiting the relationship between birefringence and force to measure airway smooth muscle contraction with PS-OCT (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Adams, David C.; Hariri, Lida P.; Holz, Jasmin A.; Szabari, Margit V.; Harris, R. Scott; Cho, Jocelyn L.; Hamilos, Daniel L.; Luster, Andrew D.; Medoff, Benjamin D.; Suter, Melissa J.

    2016-03-01

    The ability to observe airway dynamics is fundamental to forming a complete understanding of pulmonary diseases such as asthma. We have previously demonstrated that Optical Coherence Tomography (OCT) can be used to observe structural changes in the airway during bronchoconstriction, but standard OCT lacks the contrast to discriminate airway smooth muscle (ASM) bands- ASM being responsible for generating the force that drives airway constriction- from the surrounding tissue. Since ASM in general exhibits a greater degree of birefringence than the surrounding tissue, a potential solution to this problem lies in the implementation of polarization sensitivity (PS) to the OCT system. By modifying the OCT system so that it is sensitive to the birefringence of tissue under inspection, we can visualize the ASM with much greater clarity and definition. In this presentation we show that the force of contraction can be indirectly measured by an associated increase in the birefringence signal of the ASM. We validate this approach by attaching segments of swine trachea to an isometric force transducer and stimulating contraction, while simultaneously measuring the exerted force and imaging the segment with PS-OCT. We then show how our results may be used to extrapolate the force of contraction of closed airways in absence of additional measurement devices. We apply this technique to assess ASM contractility volumetrically and in vivo, in both asthmatic and non-asthmatic human volunteers.

  18. Detecting vacuum birefringence with x-ray free electron lasers and high-power optical lasers: a feasibility study

    NASA Astrophysics Data System (ADS)

    Schlenvoigt, Hans-Peter; Heinzl, Tom; Schramm, Ulrich; Cowan, Thomas E.; Sauerbrey, Roland

    2016-02-01

    We study the feasibility of measuring vacuum birefringence by probing the focus of a high-intensity optical laser with an x-ray free electron laser (XFEL). This amounts to performing a new type of QED precision experiment, employing only laser pulses, hence space- and time-dependent fields. To set the stage, we briefly review the status of QED precision tests and then focus on the example of vacuum birefringence. Adopting a realistic laser beam model in terms of pulsed Gaussian beams we calculate the induced phase shift and translate it into an experimental signal, counting the number of photons with flipped polarization. We carefully design a detailed experiment at the European XFEL operating in self-seeded mode, supplemented by a petawatt class optical laser via the HIBEF project. Assuming all components to represent the current state of the art, in particular the x-ray polarizers, realistic estimates of signal-to-noise ratios plus ensuing acquisition times are provided. This is accompanied by a statistical analysis of the impact of poor laser focus overlap either due to timing and pointing jitter as well as limited alignment accuracy. A number of parasitic effects are analyzed together with appropriate countermeasures. We conclude that vacuum birefringence can indeed be measured upon combining an XFEL with a high-power optical laser if depolarization effects in the x-ray lenses can be controlled.

  19. Optical birefringence and its critical behavior in the vicinity of nematic-smectic A phase transition in a binary mixture

    NASA Astrophysics Data System (ADS)

    Sarkar, Sudipta Kumar; Barman, Purna Chandra; Das, Malay Kumar

    2014-08-01

    Optical birefringence (Δn) measurements as a function of temperature have been performed for binary mixtures of octyloxy cyanobiphenyl (8OCB) and octyl cyanobiphenyl (8CB) liquid crystals by means of a high resolution temperature scanning technique. The temperature dependence of the birefringence (Δn) was determined from the transmitted intensity data for wavelengths λ=532 nm. Using a fitting procedure consistent with the mean field theory and the first order nature of nematic-isotropic (N-I) phase transition, the order parameter critical exponent β has been determined. The critical behavior of the nematic-smectic A (N-SmA) phase transition has been investigated from the high resolution birefringence data and the nature of this transition in the mixtures has been assessed. From the evolution of the critical exponent α, it has been possible to predict the limiting value of the McMillan ratio for the tricritical point (TCP) as well as the 3D-XY universality class.

  20. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    NASA Astrophysics Data System (ADS)

    Sutter, John P.; Dolbnya, Igor P.; Collins, Stephen P.; Harris, Kenneth D. M.; Edwards-Gau, Gregory R.; Palmer, Benjamin A.

    2015-04-01

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

  1. Immunoassays for the cancer biomarker CA125 based on a large-birefringence nematic liquid-crystal mixture

    PubMed Central

    Sun, Shih-Hung; Lee, Mon-Juan; Lee, Yun-Han; Lee, Wei; Song, Xiaolong; Chen, Chao-Yuan

    2014-01-01

    The use of fluorescence is ubiquitously found in the detection of immunoreaction; though with good sensitivity, this technique requires labeling as well as other time-consuming steps to perform the measurement. An alternative approach involving liquid crystals (LCs) was proposed, based on the fact that an immunocomplex can disturb the orientation of LCs, leading to an optical texture different from the case when only antigen or antibody exists. This method is label-free, easy to manipulate and low-cost. However, its sensitivity was low for practical usage. In this study, we adopted a high-birefringence liquid crystal (LC) to enhance the sensitivity for the immunodetection. Experiments were performed, targeting at the cancer biomarker CA125. We showed that the larger birefringence (Δn = 0.33 at 20 °C) amplifies the detected signal and, in turn, dramatically improves the detection limit. To avoid signal loss from conventional rinsing steps in immunodetection, CA125 antigen and antibody were reacted before immobilized on substrates. We studied the specific binding events and obtained a detection limit as low as 1 ng/ml. The valid temperature ranges were compared by using the typical single-compound LC 5CB and the high-birefringence LC mixture. We further investigated time dependency of the optical textures and affirmed the capability of LC-based immunodetection in distinguishing between specific and nonspecific antibodies. PMID:25657889

  2. Use of dome (meniscus) lenses to eliminate birefringence and tensile stresses in spatial filters for the Nova laser

    SciTech Connect

    Pitts, J.H.; Kyrazis, D.T.; Seppala, L.G.; Bumpas, S.E.

    1990-10-22

    We document the concept and the design method for dome lenses that have a compressive pressure applied to the periphery. Dome (meniscus) lenses can eliminate both birefringence and tensile stresses if used in evacuated spatial filters where a pressure difference is present across the lenses. Calculations show that spatial filter birefringence is an insignificant 3 nm within the portion of a 740-mm Nova spatial filter dome lens illuminated by the laser beam. Membrane stresses are everywhere compressive, varying from {minus}1.2 to {minus}2.4 MPa, and are nearly uniform over the illuminated portion of the lens. Eliminating sources of birefringence on the Nova laser could increase the energy on target with Type II/Type II frequency conversion from {approximately}50% to the {approximately}70% level attainable with Type I/Type II frequency conversion. Eliminating tensile stresses may reduce the damage and catastrophic failure that has occurred in some Nova spatial filter input lenses. The major disadvantage of using dome lenses on Nova is the cost of new lenses which could range up to $50,000 per lens for the material and $20,000 per lens for finishing. 15 refs., 7 figs.

  3. Study of Collagen Birefringence in Different Grades of Oral Squamous Cell Carcinoma Using Picrosirius Red and Polarized Light Microscopy

    PubMed Central

    Arun Gopinathan, Pillai; Kokila, Ganganna; Jyothi, Mahadesh; Ananjan, Chatterjee; Pradeep, Linganna; Humaira Nazir, Salroo

    2015-01-01

    Objectives. The present study was done to evaluate birefringence pattern of collagen fibres in different grades of oral squamous cell carcinoma using Picrosirius red stain and polarization microscopy and to determine if there is a change in collagen fibres between different grades of oral squamous cell carcinoma. Materials and Methods. Picrosirius red stained 5 μm thick sections of previously diagnosed different grades of squamous cell carcinoma and normal oral mucosa were studied under polarization microscopy for arrangement as well as birefringence of collagen fibres around tumour islands. Results. It was found that thin collagen fibres increased and thick collagen fibres decreased with dedifferentiation of OSCC (P < 0.0001). It was observed that there was change in polarization colours of thick fibres from yellowish orange to greenish yellow with dedifferentiation of OSCC indicating loosely packed fibres (P < 0.0001). Conclusion. There was a gradual change of birefringence of collagen from yellowish orange to greenish yellow from well to poorly differentiated squamous cell carcinoma, indicating that there is a change from mature form of collagen to immature form as tumour progresses. Studying collagen fibres with Picrosirius red for stromal changes around tumour islands along with routine staining may help in predicting the prognosis of tumour. PMID:26587310

  4. Theoretical analysis of the background intensity distribution in X-ray Birefringence Imaging using synchrotron bending-magnet radiation

    SciTech Connect

    Sutter, John P. Dolbnya, Igor P.; Collins, Stephen P.; Harris, Kenneth D. M.; Edwards-Gau, Gregory R.; Palmer, Benjamin A.

    2015-04-28

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

  5. Photon-pair generation by intermodal spontaneous four-wave mixing in birefringent, weakly guiding optical fibers

    NASA Astrophysics Data System (ADS)

    Garay-Palmett, K.; Cruz-Delgado, D.; Dominguez-Serna, F.; Ortiz-Ricardo, E.; Monroy-Ruz, J.; Cruz-Ramirez, H.; Ramirez-Alarcon, R.; U'Ren, A. B.

    2016-03-01

    We present a theoretical and experimental study of the generation of photon pairs through the process of spontaneous four-wave mixing (SFWM) in a few-mode, birefringent fiber. Under these conditions, multiple SFWM processes are in fact possible, each associated with a different combination of transverse modes for the four waves involved. We show that in the weakly guiding regime, for which the propagation modes may be well approximated by linearly polarized modes, the departure from circular symmetry due to the fiber birefringence translates into conservation rules, which retain elements from azimuthal and rectangular symmetries: both OAM and parity must be conserved for a process to be viable. We have implemented a SFWM source based on a bowtie birefringent fiber, and have measured for a collection of pump wavelengths the SFWM spectra of each of the signal and idler photons in coincidence with its partner photon. We have used this information, together with knowledge of the transverse modes into which the signal and idler photons are emitted, as input for a genetic algorithm, which accomplishes two tasks: (i) the identification of the particular SFWM processes that are present in the source, and (ii) the characterization of the fiber used.

  6. Graded Achievement, Tested Achievement, and Validity

    ERIC Educational Resources Information Center

    Brookhart, Susan M.

    2015-01-01

    Twenty-eight studies of grades, over a century, were reviewed using the argument-based approach to validity suggested by Kane as a theoretical framework. The review draws conclusions about the meaning of graded achievement, its relation to tested achievement, and changes in the construct of graded achievement over time. "Graded…

  7. Intermodal interferometer for strain and temperature sensing fabricated in birefringent boron doped microstructured fiber.

    PubMed

    Statkiewicz-Barabach, G; Carvalho, J P; Frazão, O; Olszewski, J; Mergo, P; Santos, J L; Urbanczyk, W

    2011-07-20

    We present a compact in-line fiber interferometric sensor fabricated in a boron doped two-mode highly birefringent microstructured fiber using a CO(2) laser. The intermodal interference arises at the fiber output due to coupling between the fundamental and the first order modes occurring at two fiber tapers distant by a few millimeters. The visibility of intermodal interference fringes is modulated by a polarimetric differential signal and varies in response to measurand changes. The proposed interferometer was tested for measurements of the strain and temperature, respectively, in the range of 20-700 °C and 0-17 mstrain. The sensitivity coefficients corresponding to fringe displacement and contrast variations are equal respectively for strain -2.51 nm/mstrain and -0.0256 1/mstrain and for temperature 16.7 pm/°C and 5.74×10(-5) 1/°C. This allows for simultaneous measurements of the two parameters by interrogation of the visibility and the displacement of interference fringes. PMID:21772355

  8. Linear birefringence and dichroism in citric acid coated Fe3O4 magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lin, Jing-Fung; Tsai, Chun-Chin; Lee, Meng-Zhe

    2014-12-01

    To prepare highly dispersed water-based Fe3O4 magnetic nanoparticles (MNPs), we adopted the co-precipitation method and used citric acid (CA) as the surfactant. Via transmission electronic microscopy, dynamic light scattering, and X-ray diffractometry, we characterized the dispersibility and size of the products. Through two single-parameter experiments, including the pH value of suspension and the action of double centrifugations, the appropriate parameters' values were determined. Further, to produce CA coated MNPs with good magneto-optical properties as high retardance and low dichroism, the orthogonal design method was used to find the optimal parameters' values, including pH value of suspension after coating was 5, molar ratio of CA to Fe3O4 MNPs was 0.06, volume of CA was 40 ml, and coating temperature was 70 °C. Above all, the linear birefringence and dichroism of the best CA coated ferrofluid we produced were measured by a Stokes polarimeter as 23.6294° and 0.3411 under 64.5 mT, respectively. Thus, the biomedical applications could be performed hereafter.

  9. Low-birefringent and highly tough nanocellulose-reinforced cellulose triacetate.

    PubMed

    Soeta, Hiroto; Fujisawa, Shuji; Saito, Tsuguyuki; Berglund, Lars; Isogai, Akira

    2015-05-27

    Improvement of the mechanical and thermal properties of cellulose triacetate (CTA) films is required without sacrificing their optical properties. Here, poly(ethylene glycol) (PEG)-grafted cellulose nanofibril/CTA nanocomposite films were fabricated by casting and drying methods. The cellulose nanofibrils were prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and amine-terminated PEG chains were grafted onto the surfaces of the TEMPO-oxidized cellulose nanofibrils (TOCNs) by ionic bonds. Because of the nanosize effect of TOCNs with a uniform width of ∼3 nm, the PEG-TOCN/CTA nanocomposite films had high transparency and low birefringence. The grafted PEG chains enhanced the filler-matrix interactions and crystallization of matrix CTA molecules, resulting in the Young's modulus and toughness of CTA film being significantly improved by PEG-grafted TOCN addition. The coefficient of thermal expansion of the original CTA film was mostly preserved even with the addition of PEG-grafted TOCNs. These results suggest that PEG-TOCNs are applicable to the reinforcement for transparent optical films. PMID:25946413

  10. Narrow band pass filter using birefringence film and quarter-wave film

    NASA Astrophysics Data System (ADS)

    Lee, Dong-kun; Song, Jang-Kun

    2016-03-01

    While a pixel in a color image has three colorimetric information of RGB, that in a spectral image contains full spectral information, several tens times more information compared to the color image. Hence, the spectral image is widely applicable in biology, material science, and environmental science. Although several methods for spectral image acquisition have been suggested to date, those methods are expensive, bulky, or slow in actual device. In this work, we designed a novel type of tunable narrow band-pass filter using rotatable polarizer, quarter-wave plate, and birefringence films. Different from the conventional Lyot-Ohman type filter, we do not use a liquid crystal layer. The selection of wavelength is made by rotating the polarizer in our filter set, and adopted a piezoelectric rotational actuator for that. We simulated to find the optimal conditions of the filter set, and finally, fabricated a filter module. The minimum band width was 5 nm, which is suitable for usual spectral imaging and can be reduced further if necessary, and the wavelength of light passing through the filter set was continuously selectable. After setting the filter in a microscope, we obtained a spectral image set for a bio sample that contained full spectrum information in each pixel. Using image processing, we could demonstrate to read out the spectral information for any selected position.

  11. Kinetic Monte Carlo simulations for birefringence relaxation of photo-switchable molecules on a surface

    NASA Astrophysics Data System (ADS)

    Tavarone, Raffaele; Charbonneau, Patrick; Stark, Holger

    2016-03-01

    Recent experiments have demonstrated that in a dense monolayer of photo-switchable dye methyl-red molecules the relaxation of an initial birefringence follows a power-law decay, typical for glass-like dynamics. The slow relaxation can efficiently be controlled and accelerated by illuminating the monolayer with circularly polarized light, which induces trans-cis isomerization cycles. To elucidate the microscopic mechanism, we develop a two-dimensional molecular model in which the trans and cis isomers are represented by straight and bent needles, respectively. As in the experimental system, the needles are allowed to rotate and to form overlaps but they cannot translate. The out-of-equilibrium rotational dynamics of the needles is generated using kinetic Monte Carlo simulations. We demonstrate that, in a regime of high density and low temperature, the power-law relaxation can be traced to the formation of spatio-temporal correlations in the rotational dynamics, i.e., dynamic heterogeneity. We also show that the nearly isotropic cis isomers can prevent dynamic heterogeneity from forming in the monolayer and that the relaxation then becomes exponential.

  12. Nanoparticle-mediated monitoring of carbohydrate-lectin interactions using Transient Magnetic Birefringence.

    PubMed

    Köber, Mariana; Moros, Maria; Franco Fraguas, Laura; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

    2014-12-16

    The development of sensitive and easy-to-use biosensors that allow an adequate characterization of specific weak biological interactions like carbohydrate-lectin interactions still remains challenging today. Nanoparticles functionalized with carbohydrates are one of the most powerful systems for studying carbohydrate-lectin interactions, because they mimic the multivalent presentation of carbohydrates encountered in nature, for example when viruses and bacteria bind to cells. On the basis of the model system glucose-Concanavalin A (ConA), we explore the application of Transient Magnetic Birefringence (TMB) to study these weak interactions, using glucose-functionalized colloidal magnetite nanoparticles (NPs) as probes. We demonstrate that the binding dynamics can be monitored and derive a model to obtain the apparent cooperativity. For our studies, we use nanoparticles of 6 and 8 nm in diameter. The ConA-generated response shows apparent cooperativity, due to the cross-linking of nanoparticles by the ConA tetramer which has four binding sites. Cooperativity is higher for 6 nm NPs, possibly due to a better accessibility of all four ConA binding sites on smaller NPs, enhancing cross-linking. For this system, we find a detection limit of 3-23 nM. PMID:25417550

  13. A static birefringent interferometer for the measurement of upper atmospheric winds

    NASA Astrophysics Data System (ADS)

    Langille, Jeffery A.; Ward, William E.; Gault, William A.; Scott, Alan; Touahri, Driss; Bell, Andrew

    2013-10-01

    An instrument concept called the Birefringent Imaging Doppler Wind Interferometer (BIDWIN) is being validated in the Atmospheric and Space Physics Lab at the University of New Brunswick in collaboration with COM DEV Ltd (Ottawa, Canada) to determine its capabilities for measuring Doppler wind fields in the Earth's nightglow. The instrument is adapted from a similar approach used to obtain two dimensional images of high speed (~1000 m/s) flow fields in plasmas at the Australian National University. For that application the precision of the wind measurements was not explored in detail. With BIDWIN, the intent is to obtain ~ 5 m/s precision on each bin of a CCD image of the wind field. An examination of the instrument concept and sensitivity of the wind measurements made using this approach is undertaken to determine the feasibility of this criterion. The BIDWIN has the advantage over other instruments that can be used for a similar purpose (such as the field widened Michelson interferometer and Fabry-Perot interferometer) in that it has no moving parts, has a large throughput, is light weight and is relatively cheap to construct. In this paper, the instrument concept is presented and the ideal and non-ideal instrument effects are explored. Calibration measurements conducted using a proto-type of the instrument are used to verify the instrument concept and confirm the feasibility of the approach for making atmospheric wind measurements.

  14. Polycyanurate ester resins with low loss and low birefringence for use in integrated optics

    NASA Astrophysics Data System (ADS)

    Dreyer, Christian J.; Bauer, Monika; Bauer, Joerg; Keil, Norbert; Yao, HuiHai; Zawadzki, Crispin

    2001-12-01

    In the age of information society and internet the requirements of fast transfers of large data streams for different applications are growing day by day. Killer-applications like teleconferencing, video-on-demand, online-games, virtual reality etc. are waiting in the wings. The optical network technology using the great bandwidth of glass fibre is the most suitable technology for these demands. Not only glass fibre is required, but also a broad range of optical components, such as multiplexers, demultiplexers, optical switches, optical attenuators, splitters and combiners, which are usually produced in silica technology. Polymeric materials are becoming more and more interesting for these applications, since they promise for instance lower power consumption and a reduction of production costs compared to their silica based pendants. Polycyanurate ester resins are a relatively new class of high-performance polymers with outstanding properties, for example high thermal stability, low optical loss, low dielectric constant, good adhesion and outstanding mechanical properties. This paper focuses on optical loss and birefringence of such materials at 1550 nm. The results lead the way to optimization for use in integrated optics and for the production of embedded waveguides and devices.

  15. A birefringent polarization modulator: Application to phase measurement in conoscopic interference patterns

    NASA Astrophysics Data System (ADS)

    Veiras, F. E.; Garea, M. T.; Perez, L. I.

    2016-04-01

    Conoscopic interferometry for crystal characterization is a very well-known technique with increasing applications in different fields of technology. The advantage of the scheme proposed here is the introduction of a polarization modulator that allows the recovery of the phase information contained in conoscopic interferograms. This represents a real advantage since the most relevant physical information of the sample under study is usually contained in the phase of the fringe pattern. Moreover, this technique works successfully even when there are no visible fringes. The setup employed is a simple conoscopic interferometer where the elements under study correspond to two birefringent crystal slabs and a commercial mica wave plate. It allows the crystals to be characterized and the wave plate retardance to be measured as a function of the angle of incidence. The modulator itself consists of a single tiltable crystal plate which, by means of phase shifting techniques, permits the recovery of a phase map for each sample. It is inexpensive and it can be easily calibrated, so it works with a wide range of phase shifting interferometry algorithms. We show that our scheme is easily adaptable to algorithms that require either a low or high amount of interferograms.

  16. Field-Effect Birefringent Spin Lens in Ultrathin Film of Magnetically Doped Topological Insulators

    NASA Astrophysics Data System (ADS)

    Tang, Peizhe; Zhao, Lu; Gu, Bing-Lin; Duan, Wenhui

    2014-03-01

    We investigate the low-energy electron dynamics in two-dimensional ultrathin film of magnetically doped topological insulators in the context of gate-tuned coherent spin manipulation. Our first-principles calculations for such film unambiguously identify its spin-resolved topological band structure arising from spin-orbit coupling and time-reversal symmetry breaking. Exploiting this characteristic, we predict a negative birefraction for chiral electron tunneling through a gate-controlled p-n interface in the film, analogous to optical birefringence. By fine-tuning the gate voltage, a series of unusual phenomena, including electron double focusing, spatial modulation of spin polarizations, and quantum-interferenceinduced beating patterns, could be efficiently implemented, offering a powerful platform to establish spin-resolved electron optics by all-electrical means. L. Z. and P. T. contributed equally to this work. We acknowledge support from the National Natural Science Foundation of China (Grants No. 11204154 and No. 11074139) and the Ministry of Science and Technology of China (Grants No. 2011CB606405 and No. 2011CB921901).

  17. Vacuum birefringence in strong magnetic fields: (II) Complex refractive index from the lowest Landau level

    SciTech Connect

    Hattori, Koichi; Itakura, Kazunori

    2013-07-15

    We compute the refractive indices of a photon propagating in strong magnetic fields on the basis of the analytic representation of the vacuum polarization tensor obtained in our previous paper. When the external magnetic field is strong enough for the fermion one-loop diagram of the polarization tensor to be approximated by the lowest Landau level, the propagating mode in parallel to the magnetic field is subject to modification: The refractive index deviates from unity and can be very large, and when the photon energy is large enough, the refractive index acquires an imaginary part indicating decay of a photon into a fermion–antifermion pair. We study dependences of the refractive index on the propagating angle and the magnetic-field strength. It is also emphasized that a self-consistent treatment of the equation which defines the refractive index is indispensable for accurate description of the refractive index. This self-consistent treatment physically corresponds to consistently including the effects of back reactions of the distorted Dirac sea in response to the incident photon. -- Highlights: •Vacuum birefringence and photon decay are described by the complex refractive index. •Resummed photon vacuum polarization tensor in the lowest Landau level is used. •Back reactions from the distorted Dirac sea are self-consistently taken into account. •Self-consistent treatment drastically changes structure in photon energy dependence. •Dependences on photon propagation angle and magnetic-field strength are presented.

  18. Collagen birefringence in skin repair in response to red polarized-laser therapy

    NASA Astrophysics Data System (ADS)

    da Silva, Daniela d. F. T.; Vidal, Benedicto d. C.; Zezell, Denise M.; Zorn, Telma M. T.; Núñez, Silvia C.; Ribeiro, Martha S.

    2006-03-01

    We use the optical path difference (OPD) technique to quantify the organization of collagen fibers during skin repair of full-thickness burns following low-intensity polarized laser therapy with two different polarization incidence vectors. Three burns are cryogenerated on the back of rats. Lesion L|| is irradiated using the electric field vector of the polarized laser radiation aligned in parallel with the rat's occipital-caudal direction. Lesion L⊥ is irradiated using the electric field vector of the polarized laser radiation aligned perpendicularly to the aforementioned orientation. Lesion C is untreated. A healthy area labeled H is also evaluated. The tissue samples are collected and processed for polarized light microscopy. The overall finding is that the OPD for collagen fibers depends on the electric field vector of the incident polarized laser radiation. No significant differences in OPDs are observed between L|| and H in the center, sides, and edges of the lesion. Lesions irradiated using the electric field vector of the polarized laser radiation aligned in parallel with the rat's occipital-caudal direction show higher birefringence, indicating that collagen bundles in these lesions are more organized.

  19. An Affordable, Indigenous Polarizer-Analyser System with Inbuilt Retardation Plate Function to Detect Birefringence using 3D Glasses: An Experience

    PubMed Central

    Sudhir, Dange Prasad; Saksena, Annapurna; Khurana, Nita

    2016-01-01

    Introduction Polarizing microscope plays a vital role in few but unique situations. A pair of cross polarizers is used to confirm the presence of birefringent substances. Also, a red retardation plate is needed to evaluate the sign of birefringence. However, a polarizing microscope especially with retardation plate is very expensive. Thus, an affordable yet effective substitute using the 3D Polaroid glasses used for ‘3D movies’ would enable widespread use of the polarizing system. Aim To study the use of 3D polaroid glasses procured from cinema halls in detecting birefringence substances and to study the red retardation plate function in them. Materials and Methods Passive 3D Polaroid glasses were procured from cinema halls. They were arranged in aspecific manner to obtain polarized light. Red retardation plate function can be obtained by changing the arrangement of the glasses. These glasses were used with various available models of different light microscope manufacturers. Various specimens observed included amyloid deposits, woven and lamellar bone, skeletal muscle striations, urate crystals, cholesterol crystals, suture material and glove powder. The comparison was based on subjective interpretation of intensity and quality of birefringence. Sign of birefringence was also determined whenever relevant. Results The birefringence observed by our system was comparable to the commercially available polarizing system with respect to intensity and quality. Also, there were no false positive /negative results when compared with the commercial Polarizing microscope. Moreover, the system had an inbuilt red retardation plate to determine sign of birefringence. Conclusion The system is efficient, cheap, easily accessible, portable and compatible with all models of light microscopes. PMID:26894072

  20. Limits on low energy photon-photon scattering from an experiment on magnetic vacuum birefringence

    SciTech Connect

    Bregant, M.; Cantatore, G.; Della Valle, F.; Lozza, V.; Milotti, E.; Raiteri, G.; Zavattini, E.; Carusotto, S.; Polacco, E.; Cimino, R.; Di Domenico, G.; Zavattini, G.; Gastaldi, U.; Ruoso, G.; Karuza, M.

    2008-08-01

    Experimental bounds on induced vacuum magnetic birefringence can be used to improve present photon-photon scattering limits in the electronvolt energy range. Measurements with the Polarizzazione del Vuoto con Laser apparatus [E. Zavattini et al., Phys. Rev. D 77, 032006 (2008)] at both {lambda}=1064 and 532 nm lead to bounds on the parameter A{sub e}, describing nonlinear effects in QED, of A{sub e}{sup (1064)}<6.6x10{sup -21} T{sup -2}-1064 nm and A{sub e}{sup (532)}<6.3x10{sup -21} T{sup -2}-532 nm, respectively, at 95% confidence level, compared to the predicted value of A{sub e}=1.32x10{sup -24} T{sup -2}. The total photon-photon scattering cross section may also be expressed in terms of A{sub e}, setting bounds for unpolarized light of {sigma}{sub {gamma}}{sub {gamma}}{sup (1064)}<4.6x10{sup -62} m{sup 2} and {sigma}{sub {gamma}}{sub {gamma}}{sup (532)}<2.7x10{sup -60} m{sup 2}. Compared to the expected QED scattering cross section these results are a factor of {approx_equal}2x10{sup 7} higher and represent an improvement of a factor about 500 on previous bounds based on ellipticity measurements and of a factor of about 10{sup 10} on bounds based on direct stimulated scattering measurements.