WorldWideScience

Sample records for optical polarization monitoring

  1. General demonstration of principal states of polarization and real-time monitoring of polarization mode dispersion in optical fibres

    Institute of Scientific and Technical Information of China (English)

    Dong Hui; Wu Chong-Qing; Fu Song-Nian

    2004-01-01

    We investigated the general properties of polarization effects in optical fibres and demonstrated the existence of socalled principal states of polarization (PSP), which mean the fixed points in mathematics, in different polarization effects,such as birefringence and polarization mode dispersion, by using fixed point theory. Furthermore, a time evolution vector is defined to describe the time evolution of polarization state in optical fibres, which is used to investigate the time evolution of polarization mode dispersion vector (PDV), including differential group delay and PSP. The experimentalresults of real-time monitoring of PDV by using this method are reported. To our knowledge, this is the first report on monitoring PSP evolution in optical fibres.

  2. Longitudinal monitoring of demineralization peripheral to orthodontic brackets using cross polarization optical coherence tomography.

    Science.gov (United States)

    Nee, Alexander; Chan, Kenneth; Kang, Hobin; Staninec, Michal; Darling, Cynthia L; Fried, Daniel

    2014-05-01

    The aim of this study was to test the hypothesis that cross-polarization optical coherence tomography (CP-OCT) can be used to longitudinally monitor demineralization peripheral to orthodontic brackets in an extended clinical study. A high-speed CP-OCT system was used to acquire 3D volumetric images of the area at the base of orthodontic brackets over a period of 12 months after placement. The reflectivity was measured at 3-month intervals for 12 months to determine if there was increased demineralization. Two teeth were monitored on 20 test subjects and the brackets were bonded using two types of adhesives. This was a randomized controlled clinical study with a split mouth design such that each subject served as his or her own control. On one side, the control premolar was bonded with a bonding agent (Adper Scotchbond from 3M ESPE, St. Paul, MN) and composite (Transbond XT from 3M Unitek, Monrovia, CA) that lacked fluoride. On the other side, the experimental premolar was bonded with a fluoride releasing glass ionomer cement (GC Fuji Ortho LC from GC America, Alsip, IL). There was a small but significant increase in the calculated lesion depth and integrated reflectivity over that depth (ΔR) for both adhesive types (pfluoride releasing glass ionomer cement and the conventional composite. CP-OCT was able to measure a significant increase in demineralization (p<0.0001) at the base of orthodontic brackets over a period of 12 months. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Evidence for anomalous optical transition radiation linear polarization effects in beam-profile monitors

    Directory of Open Access Journals (Sweden)

    A. H. Lumpkin

    2013-10-01

    Full Text Available Investigations of the effects of optical transition radiation (OTR polarization components on beam profiles are presented. The transverse profiles are examined using the OTR perpendicular and parallel polarization components with respect to the dimension of interest. We observed ∼15% projected profile size reductions with the perpendicularly polarized components on a 65-μm beam image size case at 14 MeV, a 150-μm beam image size at 4.5 GeV, and a 1100-μm beam image size at 7 GeV. These effects are all several times larger than expected (and anomalous in this sense when compared to the standard OTR point-spread function calculations. We propose the time-averaged induced-current distribution which generates the OTR represents the actual beam size more faithfully with the perpendicular polarization component and recommend its routine use and subsequent deconvolution.

  4. Variability and stability in blazar jets on time scales of years: Optical polarization monitoring of OJ287 in 2005-2009

    OpenAIRE

    Villforth, C.; Nilsson, K.; Heidt, J.; Takalo, L. O.; Pursimo, T.; Berdyugin, A.; Lindfors, E.; Pasanen, M.; Winiarski, M.; Drozdz, M.; Ogloza, W.; Kurpinska-Winiarska, M.; Siwak, M.; Koziel-Wierzbowska, D.; Porowski, C.

    2009-01-01

    (Abridged) OJ287 is a BL Lac object that has shown double-peaked bursts at regular intervals of ~12 yr during the last ~40 yr. We analyse optical photopolarimetric monitoring data from 2005-2009, during which the latest double-peaked outburst occurred. The aim of this study is twofold: firstly, we aim to analyse variability patterns and statistical properties of the optical polarization light-curve. We find a strong preferred position angle in optical polarization. The preferred position angl...

  5. Innovative optical spectrometers for ice core sciences and atmospheric monitoring at polar regions

    Science.gov (United States)

    Grilli, Roberto; Alemany, Olivier; Chappellaz, Jérôme; Desbois, Thibault; Faïn, Xavier; Kassi, Samir; Kerstel, Erik; Legrand, Michel; Marrocco, Nicola; Méjean, Guillaume; Preunkert, Suzanne; Romanini, Daniele; Triest, Jack; Ventrillard, Irene

    2015-04-01

    In this talk recent developments accomplished from a collaboration between the Laboratoire Interdisciplinaire de Physique (LIPhy) and the Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) both in Grenoble (France), are discussed, covering atmospheric chemistry of high reactive species in polar regions and employing optical spectrometers for both in situ and laboratory measurements of glacial archives. In the framework of an ANR project, a transportable spectrometer based on the injection of a broadband frequency comb laser into a high-finesse optical cavity for the detection of IO, BrO, NO2 and H2CO has been realized.[1] The robust spectrometer provides shot-noise limited measurements for as long as 10 minutes, reaching detection limits of 0.04, 2, 10 and 200 ppt (2σ) for the four species, respectively. During the austral summer of 2011/12 the instrument has been used for monitoring, for the first time, NO2, IO and BrO at Dumont d'Urville Station at East of Antarctica. The measurements highlighted a different chemistry between East and West coast, with the halogen chemistry being promoted to the West and the OH and NOx chemistry on the East.[2] In the framework of a SUBGLACIOR project, an innovative drilling probe has been realized. The instrument is capable of retrieving in situ real-time vertical profiles of CH4 and δD of H2O trapped inside the ice sheet down to more than 3 km of depth within a single Antarctic season. The drilling probe containing an embedded OFCEAS (optical-feedback cavity-enhanced absorption spectroscopy) spectrometer will be extremely useful for (i) identify potential sites for investigating the oldest ice (aiming 1.5 Myrs BP records for resolving a major climate reorganization called the Mid-Pleistocene transition occurred around 1 Myrs ago) and (ii) providing direct access to past temperatures and climate cycles thanks to the vertical distribution of two key climatic signatures.[3] The spectrometer provides detection

  6. Polar low monitoring

    Science.gov (United States)

    Bobylev, Leonid; Zabolotskikh, Elizaveta; Mitnik, Leonid

    2010-05-01

    passive microwave data make it possible to retrieve several important atmospheric and oceanic parameters inside the polar lows, such as sea surface wind speed, water vapour content in the atmosphere, total liquid water content in the clouds and others, providing not only qualitative image of a vortex, but also quantitative information about these severe events, constituting a promising tool for their study and monitoring. An approach for detection and tracking of polar lows is developed utilizing the data from two sensors: SSM/I onboard DMSP and Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) onboard Aqua satellite. This approach consists of two stages. At the first stage total atmospheric water vapor fields are retrieved from SSM/I and AMSRE-E measurement data using precise Arctic polar algorithms, developed at NIERSC. These algorithms are applicable over open water. They have high retrieval accuracies under a wide range of environmental conditions. Algorithms are based on numerical simulation of brightness temperatures and their inversion by means of Neural Networks. At the second stage the vortex structures are detected in these fields, polar lows are identified and tracked and some of their parameters are calculated. A few case studies are comprehensively conducted based on SSM/I and AMSRE-E measurements and using other satellite data including visible, infrared and SAR images, QuickScat Scatterometer wind fields, surface analysis maps and re-analysis data, which demonstrated the advantages of satellite passive microwave data usage in the polar low studies.

  7. Cylindrically Polarized Nondiffracting Optical Pulses

    CERN Document Server

    Ornigotti, Marco; Szameit, Alexander

    2016-01-01

    We extend the concept of radially and azimuthally polarized optical beams to the polychromatic domain by introducing cylindrically polarized nondiffracting optical pulses. In particular, we discuss in detail the case of cylindrically polarized X-waves, both in the paraxial and nonparaxial regime. The explicit expressions for the electric and magnetic fields of cylindrically polarized X-waves is also reported.

  8. Variability and stability in blazar jets on time scales of years: Optical polarization monitoring of OJ287 in 2005-2009

    CERN Document Server

    Villforth, C; Heidt, J; Takalo, L O; Pursimo, T; Berdyugin, A; Lindfors, E; Pasanen, M; Winiarski, M; Drozdz, M; Ogloza, W; Kurpinska-Winiarska, M; Siwak, M; Koziel-Wierzbowska, D; Porowski, C; Kuzmicz, A; Krzesinski, J; Kundera, T; Wu, J -H; Zhou, X; Efimov, Y; Sadakane, K; Kamada, M; Ohlert, J; Hentunen, V -P; Nissinen, M; Dietrich, M; Assef, R J; Atlee, D W; Bird, J; DePoy, D L; Eastman, J; Peeples, M S; Prieto, J; Watson, L; Yee, J C; Liakos, A; Niarchos, P; Gazeas, K; Dogru, S; Donmez, A; Marchev, D; Coggins-Hill, S A; Mattingly, A; Keel, W C; Haque, S; Aungwerojwit, A; Bergvall, N

    2009-01-01

    (Abridged) OJ287 is a BL Lac object that has shown double-peaked bursts at regular intervals of ~12 yr during the last ~40 yr. We analyse optical photopolarimetric monitoring data from 2005-2009, during which the latest double-peaked outburst occurred. The aim of this study is twofold: firstly, we aim to analyse variability patterns and statistical properties of the optical polarization light-curve. We find a strong preferred position angle in optical polarization. The preferred position angle can be explained by separating the jet emission into two components: an optical polarization core and chaotic jet emission. The optical polarization core is stable on time scales of years and can be explained as emission from an underlying quiescent jet component. The chaotic jet emission sometimes exhibits a circular movement in the Stokes plane. We interpret these events as a shock front moving forwards and backwards in the jet, swiping through a helical magnetic field. Secondly, we use our data to assess different bi...

  9. Dense optical and near-infrared monitoring of CTA 102 during high state in 2012 with OISTER: Detection of intra-night "orphan polarized flux flare"

    CERN Document Server

    Itoh, Ryosuke; Tanaka, Yasuyuki T; Abe, Yuhei; Akitaya, Hiroshi; Arai, Akira; Hayashi, Masahiko; Hori, Takafumi; Isogai, Mizuki; Izumiura, Hideyuki; Kawabata, Koji S; Kawai, Nobuyuki; Kuroda, Daisuke; Miyanoshita, Ryo; Moritani, Yuki; Morokuma, Tomoki; Nagayama, Takahiro; Nakamoto, Jumpei; Nakata, Chikako; Oasa, Yumiko; Ohshima, Tomohito; Ohsugi, Takashi; Okumura, Shin-ichiro; Saito, Yoshihiko; Saito, Yu; Sasada, Mahito; Sekiguchi, Kazuhiro; Takagi, Yuhei; Takahashi, Jun; Takahashi, Yukihiro; Takaki, Katsutoshi; Uemura, Makoto; Ueno, Issei; Urakawa, Seitaro; Watanabe, Makoto; Yamanaka, Masayuki; Yonekura, Yoshinori; Yoshida, Michitoshi

    2013-01-01

    CTA 102, classified as a flat spectrum radio quasar at z=1.037, produced exceptionally bright optical flare in 2012 September. Following Fermi-LAT detection of enhanced gamma-ray activity, we densely monitored this source in the optical and near-infrared bands for the subsequent ten nights using twelve telescopes in Japan and South-Africa. On MJD 56197 (2012 September 27, 4-5 days after the peak of bright gamma-ray flare), polarized flux showed a transient increase, while total flux and polarization angle remained almost constant during the "orphan polarized-flux flare". We also detected an intra-night and prominent flare on MJD 56202. The total and polarized fluxes showed quite similar temporal variations, but PA again remained constant during the flare. Interestingly, the polarization angles during the two flares were significantly different from the jet direction. Emergence of a new emission component with high polarization degree (PD) up to 40% would be responsible for the observed two flares, and such a ...

  10. Applying the data fusion method to evaluation of the performance of two control signals in monitoring polarization mode dispersion effects in fiber optic links

    Science.gov (United States)

    Dashtbani Moghari, M.; Rezaei, P.; Habibalahi, A.

    2015-02-01

    With increasing distance and bit rate in fiber optic links the effects of polarization mode dispersion (PMD) have been highlighted. Since PMD has a statistical nature, using a control signal that can provide accurate information to dynamically tune a PMD compensator is of great importance. In this paper, we apply the data fusion method with the aim of introducing a method that can be used to evaluate more accurately the performance of control signals before applying them in a PMD compensation system. Firstly, the minimum and average degree of polarization (DOP_min and DOP_ave respectively) as control signals in monitoring differential group delay (DGD) for a system including all-order PMD are calculated. Then, features including the amounts of sensitivity and ambiguity in DGD monitoring are calculated for NRZ data format as DGD to bit time (DGD/T) varies. It is shown that each of the control signals mentioned has both positive and negative features for efficient DGD monitoring. Therefore, in order to evaluate features concurrently and increase reliability, we employ data fusion to fuse features of each control signal, which makes evaluating and predicting the performance of control signals possible, before applying them in a real PMD compensation system. Finally, the reliability of the results obtained from data fusion is tested in a typical PMD compensator.

  11. Polarizing Filter for Integrated Optics

    Science.gov (United States)

    Ramer, O. G.; Goss, W. C.; Goldstein, R.

    1986-01-01

    Polarizing filter for titanium-doped lithium niobate light waveguide suppresses transverse magnetic (TM) mode of light propagation while allowing transverse electric (TE) mode to continue on its way. Filter - lithium niobate crystal - is expected to find many applications in integrated optical circuits.

  12. Optical tractor Bessel polarized beams

    Science.gov (United States)

    Mitri, F. G.; Li, R. X.; Guo, L. X.; Ding, C. Y.

    2017-01-01

    Axial and transverse radiation force cross-sections of optical tractor Bessel polarized beams are theoretically investigated for a dielectric sphere with particular emphasis on the beam topological charge (or order), half-cone angle and polarization. The angular spectrum decomposition method (ASDM) is used to derive the non-paraxial electromagnetic (EM) field components of the Bessel beams. The multipole expansion method using vector spherical harmonics is utilized and appropriate beam-shape coefficients are derived in order to compute the radiation force cross-sections. The analysis has no limitation to a particular range of frequencies such that the Rayleigh, Mie or geometrical optics regimes can all be considered effectively using the present rigorous formalism. The focus of this investigation is to identify some of the tractor beam conditions so as to achieve retrograde motion of a dielectric sphere located arbitrarily in space. Numerical computations for the axial and transverse radiation force cross-sections are presented for linear, right-circular, radial, azimuthal and mixed polarizations of the individual plane waves forming the Bessel beams of zeroth- and first-order (with positive or negative helicity), respectively. As the sphere shifts off the beam's axis, the axial pulling (tractor) force is weakened. Moreover, the transverse radiation force cross-section field changes with the sphere's size factor ka (where k is the wavenumber and a is the sphere radius). Both stable and unstable equilibrium regions around the beam's axis are found, depending on the choice of ka and the half-cone angle α0. These results are particularly important in the development of emergent technologies for the photophoretic assembly of optically-engineered (meta)materials with designed properties using optical tractor (vortex) beams, particle manipulation, levitation and positioning, and other applications.

  13. Polarization Aberrations of Optical Coatings

    Science.gov (United States)

    Jota, Thiago

    This work does not limit itself to its title and touches on a number of related topics beyond it. Starting with the title, Polarization Aberrations of Optical Coatings, the immediate question that comes to mind is: what coatings? All coatings? Not all coatings, but just enough that a third person could take this information and apply it anywhere: to all coatings. The computational work-flow required to break-down the aberrations caused by polarizing events (3D vector forms of reflection and refraction) in dielectric and absorbing materials and for thick and thin films is presented. Therefore, it is completely general and of interest to the wide optics community. The example system is a Ritchey-Chretien telescope. It looks very similar to a Cassegrain, but it is not. It has hyperbolic surfaces, which allows for more optical aberration corrections. A few modern systems that use this configuration are the Hubble Space Telescope and the Keck telescopes. This particular system is a follow-up on this publication, where an example Cassegrain with aluminum coatings is characterized, and I was asked to simply evaluate it at another wavelength. To my surprise, I found a number of issues which lead me to write a completely new, one-of-its-kind 3D polarization ray-tracing code. It can do purely geometrical ray-tracing with add-on the polarization analysis capability, and more importantly: it keeps your data at your fingertips while offering all the outstanding facilities of Mathematica. The ray-tracing code and its extensive library, which can do several advanced computations, is documented in the appendix. The coatings of the Ritchey-Chretien induce a number of aberrations, primarily, but not limited to: tilt, defocus, astigmatism, and coma. I found those forms to exist in both aluminum and with a reflectance-enhancing dielectric quarter-wave multilayer coating over aluminum. The thickness of the film stack varies as function of position to present a quarter-wave of optical

  14. Optical detection dental disease using polarized light

    Energy Technology Data Exchange (ETDEWEB)

    Everett, Matthew J. (Livermore, CA); Colston, Jr., Billy W. (Livermore, CA); Sathyam, Ujwal S. (Livermore, CA); Da Silva, Luiz B. (Danville, CA); Fried, Daniel (San Francisco, CA)

    2003-01-01

    A polarization sensitive optical imaging system is used to detect changes in polarization in dental tissues to aid the diagnosis of dental disease such as caries. The degree of depolarization is measured by illuminating the dental tissue with polarized light and measuring the polarization state of the backscattered light. The polarization state of this reflected light is analyzed using optical polarimetric imaging techniques. A hand-held fiber optic dental probe is used in vivo to direct the incident beam to the dental tissue and collect the reflected light. To provide depth-resolved characterization of the dental tissue, the polarization diagnostics may be incorporated into optical coherence domain reflectometry and optical coherence tomography (OCDR/OCT) systems, which enables identification of subsurface depolarization sites associated with demineralization of enamel or bone.

  15. Optical wear monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kidane, Getnet S; Desilva, Upul P.; He, Chengli; Ulerich, Nancy H.

    2016-07-26

    A gas turbine includes first and second parts having outer surfaces located adjacent to each other to create an interface where wear occurs. A wear probe is provided for monitoring wear of the outer surface of the first part, and includes an optical guide having first and second ends, wherein the first end is configured to be located flush with the outer surface of the first part. A fiber bundle includes first and second ends, the first end being located proximate to the second end of the optical guide. The fiber bundle includes a transmit fiber bundle comprising a first plurality of optical fibers coupled to a light source, and a receive fiber bundle coupled to a light detector and configured to detect reflected light. A processor is configured to determine a length of the optical guide based on the detected reflected light.

  16. Polarization sensitive optical coherence tomography detection method

    Energy Technology Data Exchange (ETDEWEB)

    Everett, M J; Sathyam, U S; Colston, B W; DaSilva, L B; Fried, D; Ragadio, J N; Featherstone, J D B

    1999-05-12

    This study demonstrates the potential of polarization sensitive optical coherence tomography (PS-OCT) for non-invasive in vivo detection and characterization of early, incipient caries lesions. PS-OCT generates cross-sectional images of biological tissue while measuring the effect of the tissue on the polarization state of incident light. Clear discrimination between regions of normal and demineralized enamel is first shown in PS-OCT images of bovine enamel blocks containing well-characterized artificial lesions. High-resolution, cross-sectional images of extracted human teeth are then generated that clearly discriminate between the normal and carious regions on both the smooth and occlusal surfaces. Regions of the teeth that appeared to be demineralized in the PS-OCT images were verified using histological thin sections examined under polarized light microscopy. The PS-OCT system discriminates between normal and carious regions by measuring the polarization state of the back-scattered 1310 nm light, which is affected by the state of demineralization of the enamel. Demineralization of enamel increases the scattereing coefficient, thus depolarizing the incident light. This study shows that PS-OCT has great potential for the detection, characterization, and monitoring of incipient caries lesions.

  17. Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope: I. Correlations between Flux, Color, and Polarization

    CERN Document Server

    Ikejiri, Yuki; Sasada, Mahito; Ito, Ryosuke; Yamanaka, Masayuki; Sakimoto, Kiyoshi; Arai, Akira; Fukazawa, Yasushi; Ohsugi, Takashi; Kawabata, Koji S; Yoshida, Michitoshi; Sato, Shuji; Kino, Masaru

    2011-01-01

    We report on the correlation between flux, color and polarization variations on time scales of days-months in blazars, and discuss their universal aspects. We performed monitoring of 42 blazars in the optical and near-infrared bands from 2008 to 2010 using TRISPEC attached to the "Kanata" 1.5-m telescope. We found that 28 blazars exhibited "bluer-when-brighter" trends in their whole or a part of time-series data sets. This corresponds to 88% of objects that were observed for >10 days. Thus, our observation unambiguously confirmed that the "bluer-when-brighter" trend is common in the emission from blazar jets. This trend was apparently generated by a variation component with a constant and relatively blue color and an underlying red component. Prominent short-term flares on time scales of days-weeks tended to exhibit a spectral hysteresis; their rising phases were bluer than their decay phases around the flare maxima. In contrast to the strong flux-color correlation, the correlation of the flux and polarizatio...

  18. Characterization of Polarizing Splitter Optics in Extreme Environments

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Ryand; Olson, Matthew; Morelli, Gregg

    2013-01-04

    Development of laser systems capable of surviving extreme conditions experienced in military applications requires mounts and components that are able to survive these conditions. The characterization of mounted and/or bonded optical assemblies in harsh environments is critical for the development of laser and optical systems for functionality in these extreme conditions. Customized mounts, bonding assemblies and packaging strategies are utilized to develop and field reliable and robust optical subassemblies. Thin film polarizers operating at 45o and polarizing beam splitter cubes were chosen for initial testing based on past experiences, advancements in optical coating and construction technologies and material properties. Shock, vibration, shear strength, tensile strength and temperature testing are performed on mounted polarizing beam splitter cubes and thin film polarizers from two manufacturers. Previous testing showed that polarizing beam splitter cubes constructed using epoxy would become damaged in the laser resonator. The cubes being tested in this report are constructed using epoxy- free direct optical contact bonding. Thin film polarizers operating at 45o are chosen opposed to Brewster’s angle thin film polarizers to reduce the size and simplify design and construction since an optical wedge is not required. The components and mounts are each environmentally tested beyond the manufacturers’ specifications for shock, vibration, and temperature. Component functionality is monitored during and after the environmental testing. Experimental results from the testing will be discussed as will the impact on future laser resonator designs.

  19. Polarization dynamics in optical ground wire network.

    Science.gov (United States)

    Leeson, Jesse; Bao, Xiaoyi; Côté, Alain

    2009-04-20

    We report the polarization dynamics in an optical ground wire (OPGW) network for a summer period and a fall period for what is believed to be the first time. To better observe the surrounding magnetic fields contribution to modulating the state of polarization (SOP) we installed a Faraday rotating mirror to correct reciprocal birefringence from quasi-static changes. We also monitored the OPGW while no electrical current was present in the towers' electrical conductors. The spectral analysis, the arc length mapped out over a given time interval on a Poincaré sphere, histograms of the arc length, and the SOP autocorrelation function are calculated to analyze the SOP changes. Ambient temperature changes, wind, Sun-induced temperature gradients, and electrical current all have a significant impact on the SOP drift in an OPGW network. Wind-generated cable oscillations and Sun-induced temperature gradients are shown to be the dominant slow SOP modulations, while Aeolian vibrations and electrical current are shown to be the dominant fast SOP modulations. The spectral analysis revealed that the electrical current gives the fastest SOP modulation to be 300 Hz for the sampling frequency of 1 KHz. This has set the upper speed limit for real-time polarization mode dispersion compensation devices.

  20. Plasmonic Route to Reconfigurable Polarization Optics

    CERN Document Server

    Li, L; Tang, X M; Wang, S M; Wang, Q J; Zhu, S N

    2014-01-01

    Surface plasmon polariton (SPP) as a bounded mode on a metal/dielectric interface intrinsically has a definite transverse magnetic (TM) polarization that usually lacks further manipulations. However, the in-plane longitudinal components of SPP field can produce versatile polarization states when two orthogonal propagating SPP interfere with each other. Here, we demonstrated a plasmonic polarization router by designing appropriate nanohole arrays that can selectively scatter the interfered SPP fields to desired light beams. It is well proved that our device is able to reconfigure a certain input polarization to all kinds of states with respect to a scattered light. Accompanied with a composite phase modulation by diffractions, multiple focusing beams with different polarization states are simultaneously achieved, promising the possibility in polarization multiplexing and related signal processing. Our design offers a new route for achieving full control of the optical polarizations as well as the optical spin-...

  1. Polarization chaos in an optically pumped laser.

    Science.gov (United States)

    Serrat, C; Kul'minskii, A; Vilaseca, R; Corbalán, R

    1995-06-15

    We study the steady-state and dynamic behavior of an optically pumped J = 0 ? J = 1 ? J = 0 laser operating with an isotropic ring cavity and an axial magnetic field. The gain anisotropy induced by a linearly polarized pump-laser f ield leads, in the steady state, to locking of the two circularly polarized components of the laser field, which acquires a linear polarization parallel to that of the pump field. In the presence of laser intensity instabilities, however, locking does not occur, and polarization instabilities appear. For the f irst time to our knowledge, polarization chaos has been found in a laser system.

  2. Diffractive Optics of Anisotropic Polarization Gratings

    NARCIS (Netherlands)

    Xu, M.

    2009-01-01

    Diffraction gratings are being used to manipulate light in many different applications, such as in flat panel display systems, modern lighting systems, and optical recording. Diffraction gratings can be made polarization selective due to form birefringence. An alternative approach to polarization

  3. DENSE OPTICAL AND NEAR-INFRARED MONITORING OF CTA 102 DURING HIGH STATE IN 2012 WITH OISTER: DETECTION OF INTRA-NIGHT ''ORPHAN POLARIZED FLUX FLARE''

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Ryosuke; Fukazawa, Yasushi; Tanaka, Yasuyuki T. [Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Abe, Yuhei [Department of Cosmosciences, Graduate School of Science, Hokkaido University, Kita-ku, Sapporo 060-0810 (Japan); Akitaya, Hiroshi; Kawabata, Koji S.; Moritani, Yuki [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Arai, Akira [Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo-cho, Sayo, Hyogo 679-5313 (Japan); Hayashi, Masahiko [National Astronomical Observatory of Japan, Osawa 2-21-2, Mitaka, Tokyo 181-8588 (Japan); Hori, Takafumi; Nakata, Chikako [Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Isogai, Mizuki [Koyama Astronomical Observatory, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto-City 603-8555 (Japan); Izumiura, Hideyuki; Kuroda, Daisuke [Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Honjo 3037-5, Kamogata, Asakuchi, Okayama 719-0232 (Japan); Kawai, Nobuyuki [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Miyanoshita, Ryo [Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065 (Japan); Morokuma, Tomoki [Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Nagayama, Takahiro [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Nakamoto, Jumpei [Department of Earth and Planetary Sciences, School of Science, Hokkaido University, Kita-ku, Sapporo 060-0810 (Japan); Oasa, Yumiko, E-mail: itoh@hep01.hepl.hiroshima-u.ac.jp [Faculty of Education, Saitama University, 255 Shimo-Okubo, Sakura, Saitama, 338-8570 (Japan); and others

    2013-05-10

    CTA 102, classified as a flat spectrum radio quasar at z = 1.037, produced an exceptionally bright optical flare in 2012 September. Following the Fermi Large Area Telescope detection of enhanced {gamma}-ray activity, we closely monitored this source in the optical and near-infrared bands for the 10 subsequent nights using 12 telescopes in Japan and South Africa. On MJD 56197 (2012 September 27, four to five days after the peak of bright {gamma}-ray flare), polarized flux showed a transient increase, while total flux and polarization angle (PA) remained almost constant during the ''orphan polarized-flux flare.'' We also detected an intra-night and prominent flare on MJD 56202. The total and polarized fluxes showed quite similar temporal variations, but the PA again remained constant during the flare. Interestingly, the PAs during the two flares were significantly different from the jet direction. The emergence of a new emission component with a high polarization degree (PD) up to 40% would be responsible for the observed two flares, and such a high PD indicates the presence of a highly ordered magnetic field at the emission site. We argue that the well-ordered magnetic field and even the observed directions of the PA, which is grossly perpendicular to the jet, are reasonably accounted for by transverse shock(s) propagating down the jet.

  4. On the Polarization of non-Guassian optical quantum field: higher-order optical-polarization

    CERN Document Server

    Singh, Ravi S

    2013-01-01

    Polarization of light signifies transversal, anisotropic and asymmetrical statistical property of electromagnetic radiation about direction of propagation. Traditionally, optical-polarization is characterized by Stokes theory susceptible to be insufficient in assessing polarization structure of optical quantum fields and, also, does not decipher twin characteristic polarization parameters (ratio of real amplitudes and difference in phases). An alternative way, in spirit of classical description of optical-polarization, is introduced which can be generalized to deal higher-order polarization of quantum light, particularly, prepared in non-Guassian Schrodinger Cat or Cat-like states and entangled bi-modal coherent states. On account of pseudo mono-modal or multi-modal nature of such optical quantum field, higher-order polarization is seen to be highly sensitive to the basis of description.

  5. Polarized light in optics and spectroscopy

    CERN Document Server

    Kliger, David S

    1990-01-01

    This comprehensive introduction to polarized light provides students and researchers with the background and the specialized knowledge needed to fully utilize polarized light. It provides a basic introduction to the interaction of light with matter for those unfamiliar with photochemistry and photophysics. An in-depth discussion of polarizing optics is also given. Different analytical techniques are introduced and compared and introductions to the use of polarized light in various forms of spectroscopy are provided.Key Features* Starts at a basic level and develops tools for resear

  6. Optical polarization of high-energy BL Lac objects

    CERN Document Server

    Hovatta, T; Blinov, D; Pavlidou, V; Nilsson, K; Kiehlmann, S; Angelakis, E; Ramazani, V Fallah; Liodakis, I; Myserlis, I; Panopoulou, G V; Pursimo, T

    2016-01-01

    We investigate the optical polarization properties of high-energy BL Lac objects using data from the RoboPol blazar monitoring program and the Nordic Optical Telescope. We wish to understand if there are differences in the BL Lac objects that are detected with the current-generation TeV instruments compared to those that have not yet been detected. The mean polarization fraction of the TeV-detected BL Lacs is 5% while the non-TeV sources show a higher mean polarization fraction of 7%. This difference in polarization fraction disappears when the dilution by the unpolarized light of the host galaxy is accounted for. The TeV sources show somewhat lower fractional polarization variability amplitudes than the non-TeV sources. Also the fraction of sources with a smaller spread in the Q/I - U/I -plane and a clumped distribution of points away from the origin, possibly indicating a preferred polarization angle, is larger in the TeV than in the non-TeV sources. These differences between TeV and non-TeV samples seems t...

  7. Magneto-optical trap for polar molecules.

    Science.gov (United States)

    Stuhl, Benjamin K; Sawyer, Brian C; Wang, Dajun; Ye, Jun

    2008-12-12

    We propose a method for laser cooling and trapping a substantial class of polar molecules and, in particular, titanium (II) oxide (TiO). This method uses pulsed electric fields to nonadiabatically remix the ground-state magnetic sublevels of the molecule, allowing one to build a magneto-optical trap based on a quasicycling J' = J'' -1 transition. Monte Carlo simulations of this electrostatically remixed magneto-optical trap demonstrate the feasibility of cooling TiO to a temperature of 10 micrpK and trapping it with a radiation-pumping-limited lifetime on the order of 80 ms.

  8. Environmental monitoring using optical techniques

    Science.gov (United States)

    Svanberg, Sune

    2003-11-01

    An overview of optical techniques for environmental monitoring is presented. Range-resolved measurements of atmospheric pollutants can be performed using the differential absorption lidar technique. Fluorescence lidar allows assessment of vegetation status and also the conditions of the facades of historical buildings. Diode lasers provide particularly realistic schemes for atmospheric gas analysis, where certain wavelength ranges, which are not easily directly assessed, can be reached by sum- and difference frequency generation. Finally, the gas correlation principle can be used for real-time imaging of hydrocarbons. Several types of such optical environmental monitoring are illustrated with examples from research at the Lund Institute of Technology, Sweden.

  9. Rapid Polarization Activity in Optical Communication Systems

    Science.gov (United States)

    Yevick, David; Reimer, Michael; Soliman, George

    2010-03-01

    We have recently analyzed the high-speed polarization and polarization-mode-dispersion (PMD) transients associated with mechanical impacts on a dispersion compensation module consisting of several km of optical fiber. These generate in our experiments rotational frequencies of up to several hundred radians/sec on the Poincare sphere that can severely degrade the performance of both standard and non-conventional communications systems. Accordingly, we implemented several procedures for performing high-speed polarization measurements, employed these to analyze small and large amplitude excitations and compared the results with a heuristic fiber model. Theoretically, we extended our previous work on applying the Magnus expansion to the analysis of the dependence of the PMD and polarization-dependent-loss (PDL) on frequency. From these, we obtained simple procedures for modeling polarization behavior over a wide frequency range from a small number of experimental measurements. Finally, we analyzed the applicability of various models of stochastic time-dependent refractive index variations to system outage prediction.

  10. Optical signal monitoring in phase modulated optical fiber transmission systems

    Science.gov (United States)

    Zhao, Jian

    Optical performance monitoring (OPM) is one of the essential functions for future high speed optical networks. Among the parameters to be monitored, chromatic dispersion (CD) is especially important since it has a significant impact on overall system performance. In this thesis effective CD monitoring approaches for phase-shift keying (PSK) based optical transmission systems are investigated. A number of monitoring schemes based on radio frequency (RF) spectrum analysis and delay-tap sampling are proposed and their performance evaluated. A method for dispersion monitoring of differential phase-shift keying (DPSK) signals based on RF power detection is studied. The RF power spectrum is found to increase with the increase of CD and decrease with polarization mode dispersion (PMD). The spectral power density dependence on CD is studied theoretically and then verified through simulations and experiments. The monitoring sensitivity for nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) and return-to-zero differential phase-shift keying (RZ-DPSK) based systems can reach 80ps/nm/dB and 34ps/nm/dB respectively. The scheme enables the monitoring of differential group delay (DGD) and CD simultaneously. The monitoring sensitivity of CD and DGD can reach 56.7ps/nm/dB and 3.1ps/dB using a bandpass filter. The effects of optical signal-to-noise ratio (OSNR), DGD, fiber nonlinearity and chirp on the monitoring results are investigated. Two RF pilot tones are employed for CD monitoring of DPSK signals. Specially selected pilot tone frequencies enable good monitoring sensitivity with minimum influence on the received signals. The dynamic range exceeding 35dB and monitoring sensitivity up to 9.5ps/nm/dB are achieved. Asynchronous sampling technique is employed for CD monitoring. A signed CD monitoring method for 10Gb/s NRZ-DPSK and RZ-DPSK systems using asynchronous delay-tap sampling technique is studied. The demodulated signals suffer asymmetric waveform distortion if

  11. Polarization-dependent optical reflection ultrasonic detection

    Science.gov (United States)

    Zhu, Xiaoyi; Huang, Zhiyu; Wang, Guohe; Li, Wenzhao; Li, Changhui

    2017-03-01

    Although ultrasound transducers based on commercial piezoelectric-material have been widely used, they generally have limited bandwidth centered at the resonant frequency. Currently, several pure-optical ultrasonic detection methods have gained increasing interest due to their wide bandwidth and high sensitivity. However, most of them require customized components (such as micro-ring, SPR, Fabry-Perot film, etc), which limit their broad implementations. In this study, we presented a simple pure-optical ultrasound detection method, called "Polarization-dependent Reflection Ultrasonic Detection" (PRUD). It detects the intensity difference between two polarization components of the probe beam that is modulated by ultrasound waves. PRUD detect the two components by using a balanced detector, which effectively suppressed much of the unwanted noise. We have achieved the sensitivity (noise equivalent pressure) to be 1.7kPa, and this can be further improved. In addition, like many other pure-optical ultrasonic detection methods, PRUD also has a flat and broad bandwidth from almost zero to over 100MHz. Besides theoretical analysis, we did a phantom study by imaging a tungsten filament to demonstrate the performance of PRUD. We believe this simple and economic method will attract both researchers and engineers in optical and ultrasound fields.

  12. Generation and Analysis of Hidden Optical-Polarization States

    CERN Document Server

    Singh, Ravi S

    2010-01-01

    A hybrid Optical-Device (Phase-Conjugating Mirror Michelson Interferometer), made up of Phase-conjugate mirror along with ordinary mirror and Polarization Beam-splitter, is formally designed and investigated for the generation of an unusual Optical-Polarization States. This weird yet 'essentially single-mode' optical-polarization state has non-random 'ratio of amplitudes' and non-random 'sum of phases' in orthogonal bases-modes contrary to usual 'truly single-mode' optical-polarization states of which non-random 'ratio of amplitudes' and non-random 'difference of phases' serves as optical-polarization characteristic parameters. Since it is seen not to be characterized by Stokes parameters, one may, therefore, assign the name 'Hidden Optical-Polarization States (HOPS)'. HOPS are characterized by a set of parameters, namely, Hidden Optical-Polarization parameters. Formal experimental schemes are presented to experimentally measure these parameters and, thus, offering characterization of HOPS.

  13. Optical nuclear spin polarization in quantum dots

    Science.gov (United States)

    Li, Ai-Xian; Duan, Su-Qing; Zhang, Wei

    2016-10-01

    Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of nuclear spins and reduce the intrinsic nuclear spin fluctuations. Here, we polarize the nuclear spins in semiconductor quantum dot (QD) by the coherent population trapping (CPT) and the electric dipole spin resonance (EDSR) induced by optical fields and ac electric fields. By tuning the optical fields, we can obtain a powerful cooling background based on CPT for nuclear spin polarization. The EDSR can enhance the spin flip-flop rate which may increase the cooling efficiency. With the help of CPT and EDSR, an enhancement of 1300 times of the electron coherence time can be obtained after a 10-ns preparation time. Project partially supported by the National Natural Science Foundations of China (Grant Nos. 11374039 and 11174042) and the National Basic Research Program of China (Grant Nos. 2011CB922204 and 2013CB632805).

  14. Improved optical performance monitoring technique based on nonlinear optics for high-speed WDM Nyquist systems

    Science.gov (United States)

    Guesmi, Latifa; Menif, Mourad

    2016-04-01

    The field of fiber optics nonlinearity is more discussed last years due to such remarkable enhancement in the nonlinear processes efficiency. In this paper, and for optical performance monitoring (OPM), a new achievement of nonlinear effects has been investigated. The use of cross-phase modulation (XPM) and four-wave mixing (FWM) effects between input optical signal and inserted continuous-wave probe has proposed for impairments monitoring. Indeed, transmitting a multi-channels phase modulated signal at high data rate (1 Tbps WDM Nyquist NRZ- DP-QPSK) improves the sensitivity and the dynamic range monitoring. It was observed by simulation results that various optical parameters including optical power, wavelength, chromatic dispersion (CD), polarization mode dispersion (PMD), optical signal-to-noise ratio (OSNR), Q-factor and so on, can be monitored. Also, the effect of increasing the channel spacing between WDM signals is studied and proved its use for FWM power monitoring.

  15. Polarization Measurement of Spin-Polarized Electrons by Optical Electron Polarimeter

    Institute of Scientific and Technical Information of China (English)

    DING Hai-Bing; PANG Wen-Ning; LIU Yi-Bao; SHANG Ren-Cheng

    2005-01-01

    @@ The polarization of spin-polarized electrons, produced from a new GaAs spin-polarized electron source, is determined by an optical electron polarimeter. The He 3 3p → 23S1 (388.9nm) transition is used for the optical electron polarimetry. The structure and performance of the experimental setup of spin-polarized electron source and optical electron polarimeter are described. The result of polarization of 30.8% averaged spin-up and spindown polarized electrons is obtained and presented.

  16. TOWARDS 100% POLARIZATION IN THE OPTICALLY-PUMPED POLARIZED ION SOURCE.

    Energy Technology Data Exchange (ETDEWEB)

    ZELENSKI,A.; ALESSI, J.; KOKHANOVSKI, S.; KPONOU, A.; RITTER, B.J.; ZUBETS, V.

    2007-06-25

    The depolarization factors in the multi-step spin-transfer polarization technique and basic limitations on maximum polarization in the OPPIS (Optically-Pumped Polarized H{sup -} Ion Source) are discussed. Detailed studies of polarization losses in the RHIC OPPIS and the source parameters optimization resulted in the OPPIS polarization increase to 86-90%. This contributed to increasing polarization in the AGS and RHIC to 65-70%.

  17. Population redistribution in optically trapped polar molecules

    CERN Document Server

    Deiglmayr, J; Dulieu, O; Wester, R; Weidemüller, M

    2011-01-01

    We investigate the rovibrational population redistribution of polar molecules in the electronic ground state induced by spontaneous emission and blackbody radiation. As a model system we use optically trapped LiCs molecules formed by photoassociation in an ultracold two-species gas. The population dynamics of vibrational and rotational states is modeled using an ab-initio electric dipole moment function and experimental potential energy curves. Comparison with the evolution of the v"=3 electronic ground state yields good qualitative agreement. The analysis provides important input to assess applications of ultracold LiCs molecules in quantum simulation and ultracold chemistry.

  18. Is There Ecological Information in Optical Polarization Data?

    Science.gov (United States)

    Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

    2015-01-01

    Optical linear polarization? In remote sensing it's due to specular reflection. The first surface that incident light encounters - a smooth water surface or the waxy first surface of a leaf's cuticle, if it's even somewhat smooth (i.e. shiny) - will specularly reflect and linearly polarize the incident light. We provide three examples of the types of ecological information contained in remotely sensed optical linear polarization measurements. Remove the surface reflection to better see the interior. The linearly polarized light reflected by leaf surfaces contains no information about cellular pigments, metabolites, or water contained in the leaf interiors of a plant canopy, because it never enters the leaf interior to interact with them. Thus, for purposes of remotely sensing the leaf interiors of a plant canopy, the linearly polarized light should be subtracted from the total reflected light, because including it would add noise to the measurement. In particular 'minus specular' vegetation indices should allow improved monitoring of a plant canopy's physiological processes. Estimate plant development stage and yield. Wheat and sorghum grain heads, following emergence, rapidly extend upward and very quickly tower over nearby leaves, partially blocking our view of the sunlight reflected by those leaf surfaces. The resulting decrease in the amount of surface reflected and polarized sunlight, if monitored over time, potentially allows per-field estimates of the dates of the heading and flowering development stages to be interleaved with weather data in models, which is key to better estimating per-field grain yield. Similar polarization changes may occur in other grasses, such as oats, barley, corn and rice, each a crop so widely grown that it potentially affects climate at the regional scale. Wetlands Mapping. The sunlight specularly reflected by surface waters is blindingly bright, spectrally flat and polarized - all of which telegraphs that the ground area is

  19. Coherent optical communication using polarization multiple-input-multiple-output.

    Science.gov (United States)

    Han, Yan; Li, Guifang

    2005-09-19

    Polarization-division multiplexed (PDM) optical signals can potentially be demultiplexed by coherent detection and digital signal processing without using optical dynamic polarization control at the receiver. In this paper, we show that optical communications using PDM is analogous to wireless communications using multiple-input-multiple-output (MIMO) antennae and thus algorithms for channel estimation in wireless MIMO can be ready applied to optical polarization MIMO (PMIMO). Combined with frequency offset and phase estimation algorithms, simulations show that PDM quadrature phase-shift keying signals can be coherently detected by the proposed scheme using commercial semiconductor lasers while no optical phase locking and polarization control are required. This analogy further suggests the potential application of space-time coding in wireless communications to optical polarization MIMO systems and relates the problem of polarization-mode dispersion in fiber transmission to the multi-path propagation in wireless communications.

  20. Optical biosensors for environmental monitoring

    Science.gov (United States)

    Tamiya, Eiichi

    1996-11-01

    Environmental assessment is important to evaluate the overall health and ecological impact of domestic and industrial wastes. Biosensors are kinds of analytical devices which consist of biomaterials and transducers. Photoluminescence of recombinant E.coli containing lux related genes were used as indicators of environmental pollutions. This paper deals with sensitive and rapid optical sensing systems for monitoring BOD (Biochemical Oxygen Demand), toxic compounds and mutagens.

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

    CERN Document Server

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

    2016-01-01

    We present measurements of rotations of the optical polarization of blazars during the second year of operation of RoboPol, a monitoring programme of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events, and we analyse the large set of rotation events discovered in two years of observation. We investigate patterns of variability in the polarization parameters and total flux density during the rotation events and compare them to the behaviour in a non-rotating state. We have searched for possible correlations between average parameters of the polarization-plane rotations and average parameters of polarization, with the following results: (1) there is no statistical association of the rotations with contemporaneous optical flares; (2) the average fractional polarization during the rotations tends to be lower than that in a non-rotating state; (3) the average fractional polarization during rotations is correlated with the rotation rate of the polarization plane...

  2. Polarization-insensitive fiber optical parametric amplifier based on polarization diversity technique with dual parallel pumps

    Institute of Scientific and Technical Information of China (English)

    YIN Lu; SANG Xin-zhu; ZHANG Qi; XIN Xiang-jun; YU Chong-xiu; Da-xiong

    2011-01-01

    By analyzing the principle of dual-pump parametric amplification and the polarization dependent gain of fiber optical parametric amplifier (FOPA), a polarization-insensitive FOPA based on polarization-diversity technique with dual parallel pumps is presented. The performances of polarization-insensitivity, gain and BER are theoretically analyzed and numerically simulated by comparing the proposed scheme with parallel pump solution and orthogonal pump solution. The presented solution can reduce the complexity of state of polarization (SoP) of pumps.

  3. Stability analysis of polarization attraction in optical fibers

    CERN Document Server

    Turitsyn, K S

    2013-01-01

    The nonlinear cross-polarization interaction among two intense counterpropagating beams in a span of lossless randomly birefringent telecom optical fiber may lead to the attraction an initially polarization scrambled signal towards wave with a well-defined state of polarization at the fiber output. By exploiting exact analytical solutions of the nonlinear polarization coupling process we carry out a linear stability study which reveals that temporally stable stationary solutions are only obtained whenever the output signal polarization is nearly orthogonal to the input pump polarization. Moreover, we predict that polarization attraction is acting in full strength whenever equally intense signal and pump waves are used.

  4. Experimental research on dual polarized laser optical feedback microscope

    Institute of Scientific and Technical Information of China (English)

    MAO Wei; ZHANG Shu-lian; TAN Yi-dong

    2005-01-01

    The principle of laser optical feedback microscope was presented and demonstrated. Three methods to advance the vertical resolution of laser optical feedback microscope were experimentally studied. The first one is to detect the two polarized lights' intensities separately with a Wollaston prism instead of to detect the whole light's intensity. The second is that both of the two orthogonally polarized lights of a birefringent dual frequency laser are fed back. The third one is that only one of the orthogonally polarized lights is fed back. The experimental results show that the modes competition between orthogonally polarized lights can be used to improve the vertical resolution of laser optical feedback microscope effectively.

  5. Ordinary polarization singularities in three-dimensional optical fields.

    Science.gov (United States)

    Freund, Isaac

    2012-06-15

    In generic three-dimensional optical fields the canonical point polarization singularities are points of circular polarization, C points on C lines, and points of linear polarization, L points on L lines. These special points are surrounded by a sea of ordinary points. In planes oriented normal to the principle axes of the polarization ellipse at the point, every ordinary point is also a singularity, here an ordinary polarization singularity, or O point. Interactions between O points, between O points and C points, and between O points and L points are described that highlight the fact that a consistent description of optical fields containing C and L lines must include O points.

  6. Transparent thin film polarizing and optical control systems

    Directory of Open Access Journals (Sweden)

    Nelson V. Tabiryan

    2011-06-01

    Full Text Available We show that a diffractive waveplate can be combined with a phase retardation film for fully converting light of arbitrary polarization state into a polarized light. Incorporating a photonic bandgap layer into a system of such polarizers that unify different polarization states in the input light into a single polarization state at its output, rather than absorbing or reflecting half of it, we developed and demonstrated a polarization-independent optical controller capable of switching between transmittive and reflective states. The transition between those states is smoothly controlled with low-voltage and low-power sources. Using versatile fabrication methods, this “universally polarizing optical controller” can be integrated into a thin package compatible with a variety of display, spatial light modulation, optical communication, imaging and other photonics systems.

  7. Polarization-Independent All-Optical Regenerator for DPSK Data

    Directory of Open Access Journals (Sweden)

    Valeria Vercesi

    2014-05-01

    Full Text Available We demonstrate polarization-independent simultaneous all-optical phase-preserving amplitude regeneration and wavelength conversion of NRZ differential phase shift keying (DPSK data by four-wave mixing (FWM in a semiconductor optical amplifier (SOA. The dependence upon polarization state of the signals is eliminated by using a co-polarized dual-pump architecture. Investigation on the regenerative capability vs. pumps detuning shows significant BER threshold margin improvement over 6 nm conversion range.

  8. The RINGO2 and DIPOL optical polarization catalogue of blazars

    Science.gov (United States)

    Jermak, H.; Steele, I. A.; Lindfors, E.; Hovatta, T.; Nilsson, K.; Lamb, G. P.; Mundell, C.; Barres de Almeida, U.; Berdyugin, A.; Kadenius, V.; Reinthal, R.; Takalo, L.

    2016-11-01

    We present ˜2000 polarimetric and ˜3000 photometric observations of 15 γ-ray bright blazars over a period of 936 days (2008-10-11 to 2012-10-26) using data from the Tuorla blazar monitoring program (KVA DIPOL) and Liverpool Telescope (LT) RINGO2 polarimeters (supplemented with data from SkyCamZ (LT) and Fermi-LAT γ-ray data). In 11 out of 15 sources we identify a total of 19 electric vector position angle (EVPA) rotations and 95 flaring episodes. We group the sources into subclasses based on their broad-band spectral characteristics and compare their observed optical and γ-ray properties. We find that (1) the optical magnitude and γ-ray flux are positively correlated, (2) EVPA rotations can occur in any blazar subclass, four sources show rotations that go in one direction and immediately rotate back, (3) we see no difference in the γ-ray flaring rates in the sample; flares can occur during and outside of rotations with no preference for this behaviour, (4) the average degree of polarization (DoP), optical magnitude and γ-ray flux are lower during an EVPA rotation compared with during non-rotation and the distribution of the DoP during EVPA rotations is not drawn from the same parent sample as the distribution outside rotations, (5) the number of observed flaring events and optical polarization rotations are correlated, however we find no strong evidence for a temporal association between individual flares and rotations and (6) the maximum observed DoP increases from ˜10 per cent to ˜30 per cent to ˜40 per cent for subclasses with synchrotron peaks at high, intermediate and low frequencies, respectively.

  9. Optical-Fiber Fluorosensors With Polarized Light Sources

    Science.gov (United States)

    Egalon, Claudio O.; Rogowski, Robert S.

    1995-01-01

    Chemiluminescent and/or fluorescent molecules in optical-fiber fluorosensors oriented with light-emitting dipoles along transverse axis. Sensor of proposed type captures greater fraction of chemiluminescence or fluorescence and transmits it to photodetector. Transverse polarization increases sensitivity. Basic principles of optical-fiber fluorosensors described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525), "Improved Optical-Fiber Chemical Sensors" (LAR-14607), and "Improved Optical-Fiber Temperature Sensors" (LAR-14647).

  10. Optical-Fiber Fluorosensors With Polarized Light Sources

    Science.gov (United States)

    Egalon, Claudio O.; Rogowski, Robert S.

    1995-01-01

    Chemiluminescent and/or fluorescent molecules in optical-fiber fluorosensors oriented with light-emitting dipoles along transverse axis. Sensor of proposed type captures greater fraction of chemiluminescence or fluorescence and transmits it to photodetector. Transverse polarization increases sensitivity. Basic principles of optical-fiber fluorosensors described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525), "Improved Optical-Fiber Chemical Sensors" (LAR-14607), and "Improved Optical-Fiber Temperature Sensors" (LAR-14647).

  11. Polarization-dependent optics using gauge-field metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fu; Xiao, Shiyi; Li, Jensen, E-mail: j.li@bham.ac.uk [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Wang, Saisai; Hang, Zhi Hong [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China)

    2015-12-14

    We show that effective gauge field for photons with polarization-split dispersion surfaces, being realized using uniaxial metamaterials, can be used for polarization control with unique opportunities. The metamaterials with the proposed gauge field correspond to a special choice of eigenpolarizations on the Poincaré sphere as pseudo-spins, in contrary to those from either conventional birefringent crystals or optical active media. It gives rise to all-angle polarization control and a generic route to manipulate photon trajectories or polarizations in the pseudo-spin domain. As demonstrations, we show beam splitting (birefringent polarizer), all-angle polarization control, unidirectional polarization filter, and interferometer as various polarization control devices in the pseudo-spin domain. We expect that more polarization-dependent devices can be designed under the same framework.

  12. Optical Performance Monitoring and Signal Optimization in Optical Networks

    DEFF Research Database (Denmark)

    Petersen, Martin Nordal

    2006-01-01

    -optical-electrical regeneration points decreases. This thesis evaluates the impact of signal degrading effects that are becoming of increasing concern in all-optical high-speed networks due to all-optical switching and higher bit-rates. Especially group-velocity-dispersion (GVD) and a number of nonlinear effects will require......The thesis studies performance monitoring for the next generation optical networks. The focus is on all-optical networks with bit-rates of 10 Gb/s or above. Next generation all-optical networks offer large challenges as the optical transmitted distance increases and the occurrence of electrical...... enhanced attention to avoid signal degradations. The requirements for optical performance monitoring features are discussed, and the thesis evaluates the advantages and necessity of increasing the level of performance monitoring parameters in the physical layer. In particular, methods for optical...

  13. Optical monitoring of particle aggregates

    Institute of Scientific and Technical Information of China (English)

    John Gregory

    2009-01-01

    Methods for monitoring particle aggregation are briefly reviewed. Most of these techniques are based on some form of light scattering and may be greatly dependent on the optical properties of aggregates, which are not generally known. As fractal aggregates grow larger their density can become very low and this has important practical consequences for light scattering. For instance, the scattering coefficient may be much less than for solid objects, which means that the aggregates can appear much smaller than their actual size by a light transmission method. Also, for low-density objects, a high proportion of the scattered light energy is within a small angle of the incident beam, which may also be relevant for measurements with aggregates.Using the 'turbidity fluctuation' technique as an example, it is shown how the apparent size of hydroxide flocs depends mainly on the included impurity particles, rather than the hydroxide precipitate itself. Results using clay suspensions with hydrolyzing coagulants and under are discussed.

  14. PMD Monitoring using Optical Sideband Filtering

    DEFF Research Database (Denmark)

    Petersen, Martin Nordal; Sambo, N; Andriolli, N

    2009-01-01

    This paper presents a simple PMD monitoring technique based on optical sideband filtering, which requires no change to the transmitter. The method is numerically and experimentally verified and tested in a real-time PMD monitoring experiment.......This paper presents a simple PMD monitoring technique based on optical sideband filtering, which requires no change to the transmitter. The method is numerically and experimentally verified and tested in a real-time PMD monitoring experiment....

  15. Fast switchable electro-optic radial polarization retarder

    CERN Document Server

    Lim, B C; Lai, W J; Hong, M H

    2008-01-01

    A fast, switchable electro-optic radial polarization retarder (EO-RPR) fabricated using the electro-optic ceramic PMN-PT is presented. This EO-RPR is useful for fast, switchable generation of pure cylindrical vector beam. When used together with a pair of half-wave plates, the EO-RPR can change circularly polarized light into any cylindrical vector beam of interest such as radially or azimuthally polarized light. Radially and azimuthally polarized light with purities greater than 95% are generated experimentally. The advantages of using EO-RPR include fast response times, low driving voltage and transparency in a wide spectral range (500 -7000 nm).

  16. Management of dispersion, nonlinearity and polarization-dependent effects in high-speed reconfigurable WDM fiber optic communication systems

    Science.gov (United States)

    Luo, Ting

    As optical communications approach more data bandwidth, longer transmission distance, and more reconfigurability, dispersion, nonlinearity and polarization-dependent effects are becoming key issues for future all-optical fiber optic systems and networks. For ≥10 Gbit/s optical fiber transmission systems, it is critical that chromatic dispersion and polarization-mode-dispersion be well monitored and compensated using some type of dispersion monitoring and compensation. On the other hand, dispersive and nonlinear effects in optical fiber systems can also be beneficial and have applications on pulse management, all-optical signal processing and network function, which will be essential for high bite-rate optical networks and replacing the expensive optical-electrical-optical (O/E/O) conversion. In this Ph.D. dissertation, we present a detailed research on dispersion, nonlinearity, and polarization-dependent effects in high-speed optical communication systems. We have demonstrated: (i) A dynamic channel-spacing tunable multi-wavelength Erbium-doped fiber laser; (ii) Chromatic-dispersion-insensitive PMD monitoring by tracking the radio-frequency extracted from the vestigial-sideband; (iii) A method for simultaneous chromatic and polarization-mode dispersions monitoring by adding a frequency-shifted carrier; (iv) Polarization-insensitive optical parametric amplification by depolarizing the pump; (v) All optical chromatic dispersion monitoring potential for ultra-high speed (>40 Gbit/s) optical systems using cross-phase modulation in a highly nonlinear fiber; (vi) A novel fiber-based autocorrelator using polarimetric four-wave mixing effect and a tunable differential-group-delay element; (vii) A simple all-fiber-based autocorrelator by measuring the degree-of-polarization; and (viii) Reduction of pattern dependent data distortion in a stimulated Brillouin scattering based slow light element. These techniques will play key roles in future high-speed dynamic WDM optical

  17. Elliptical polarization of near-resonant linearly polarized probe light in optically pumped alkali metal vapor.

    Science.gov (United States)

    Li, Yingying; Wang, Zhiguo; Jin, Shilong; Yuan, Jie; Luo, Hui

    2017-02-20

    Optically pumped alkali metal atoms currently provide a sensitive solution for magnetic microscopic measurements. As the most practicable plan, Faraday rotation of linearly polarized light is extensively used in spin polarization measurements of alkali metal atoms. In some cases, near-resonant Faraday rotation is applied to improve the sensitivity. However, the near-resonant linearly polarized probe light is elliptically polarized after passing through optically pumped alkali metal vapor. The ellipticity of transmitted near-resonant probe light is numerically calculated and experimentally measured. In addition, we also analyze the negative impact of elliptical polarization on Faraday rotation measurements. From our theoretical estimate and experimental results, the elliptical polarization forms an inevitable error in spin polarization measurements.

  18. CCD polarization imaging sensor with aluminum nanowire optical filters.

    Science.gov (United States)

    Gruev, Viktor; Perkins, Rob; York, Timothy

    2010-08-30

    We report an imaging sensor capable of recording the optical properties of partially polarized light by monolithically integrating aluminum nanowire optical filters with a CCD imaging array. The imaging sensor, composed of 1000 by 1000 imaging elements with 7.4 μm pixel pitch, is covered with an array of pixel-pitch matched nanowire optical filters with four different orientations offset by 45°. The polarization imaging sensor has a signal-to-noise ratio of 45 dB and captures intensity, angle and degree of linear polarization in the visible spectrum at 40 frames per second with 300 mW of power consumption.

  19. Polarization-sensitive swept-source optical coherence tomography with continuous source polarization modulation

    OpenAIRE

    Yamanari, Masahiro; Makita, Shuichi; Yasuno, Yoshiaki

    2008-01-01

    We present fiber-based polarization-sensitive swept-source optical coherence tomography (SS-OCT) based on continuous source polarization modulation. The light source is a frequency swept laser centered at 1.31 μm with a scanning rate of 20 kHz. The incident polarization is modulated by a resonant electro-optic modulator at 33.3 MHz, which is one-third of the data acquisition frequency. The zeroth- and first-order harmonic components of the OCT signals with respect to the polarization modulati...

  20. Slope stability monitoring from microseismic field using polarization methodology

    Directory of Open Access Journals (Sweden)

    Yu. I. Kolesnikov

    2003-01-01

    Full Text Available Numerical simulation of seismoacoustic emission (SAE associated with fracturing in zones of shear stress concentration shows that SAE signals are polarized along the stress direction. The proposed polarization methodology for monitoring of slope stability makes use of three-component recording of the microseismic field on a slope in order to pick the signals of slope processes by filtering and polarization analysis. Slope activity is indicated by rather strong roughly horizontal polarization of the respective portion of the field in the direction of slope dip. The methodology was tested in microseismic observations on a landslide slope in the Northern Tien-Shan (Kyrgyzstan.

  1. Optical coherent detection Brillouin distributed optical fiber sensor based on orthogonal polarization diversity reception

    Institute of Scientific and Technical Information of China (English)

    Muping Song; Bin Zhao; Xianmin Zhang

    2005-01-01

    In Brillouin distributed optical fiber sensor, using optical coherent detection to detect Brillouin scattering optical signal is a good method, but there exists the polarization correlated detection problem. A novel detecting scheme is presented and demonstrated experimentally, which adopts orthogonal polarization diversity reception to resolve the polarization correlated detection problem. A laser is used as pump and reference light sources, a microwave electric-optical modulator (EOM) is adopted to produce frequency shift reference light, a polarization controller is used to control the polarization of the reference light which is changed into two orthogonal polarization for two adjacent acquisition periods. The Brillouin scattering light is coherently detected with the reference light, and the Brillouin scattering optical signal is taken out based on Brillouin frequency shift. After electronic processing, better Brillouin distributed sensing signal is obtained. A 25-km Brillouin distributed optical fiber sensor is achieved.

  2. Optical Structural Health Monitoring Device

    Science.gov (United States)

    Buckner, Benjamin D.; Markov, Vladimir; Earthman, James C.

    2010-01-01

    This non-destructive, optical fatigue detection and monitoring system relies on a small and unobtrusive light-scattering sensor that is installed on a component at the beginning of its life in order to periodically scan the component in situ. The method involves using a laser beam to scan the surface of the monitored component. The device scans a laser spot over a metal surface to which it is attached. As the laser beam scans the surface, disruptions in the surface cause increases in scattered light intensity. As the disruptions in the surface grow, they will cause the light to scatter more. Over time, the scattering intensities over the scanned line can be compared to detect changes in the metal surface to find cracks, crack precursors, or corrosion. This periodic monitoring of the surface can be used to indicate the degree of fatigue damage on a component and allow one to predict the remaining life and/or incipient mechanical failure of the monitored component. This wireless, compact device can operate for long periods under its own battery power and could one day use harvested power. The prototype device uses the popular open-source TinyOS operating system on an off-the-shelf Mica2 sensor mote, which allows wireless command and control through dynamically reconfigurable multi-node sensor networks. The small size and long life of this device could make it possible for the nodes to be installed and left in place over the course of years, and with wireless communication, data can be extracted from the nodes by operators without physical access to the devices. While a prototype has been demonstrated at the time of this reporting, further work is required in the system s development to take this technology into the field, especially to improve its power management and ruggedness. It should be possible to reduce the size and sensitivity as well. Establishment of better prognostic methods based on these data is also needed. The increase of surface roughness with

  3. Polarization Drift Channel Model for Coherent Fibre-Optic Systems

    CERN Document Server

    Czegledi, Cristian B; Agrell, Erik; Johannisson, Pontus

    2015-01-01

    A theoretical framework is introduced to model the dynamical changes of the state of polarization during transmission in coherent fibre-optic systems. The model generalizes the one-dimensional phase noise random walk to higher dimensions, accounting for random polarization drifts. The model is described in the Jones, Stokes and real 4-dimensional formalisms, and the mapping between them is derived. Such a model will be increasingly important in simulating and optimizing future optical systems, which to a higher and higher degree rely on transmission and detection on both polarizations jointly using sophisticated digital signal processing. Such analysis cannot be carried out using the more rudimentary polarization drift models in use today, which only account for deterministic effects. The proposed polarization drift model is the first of its kind and will likely be useful in a wide-range of photonics applications where stochastic polarization fluctuation is an issue.

  4. An optical encryption scheme that uses polarization of coherent light

    OpenAIRE

    Gopinathan, Unnikrishnan; David S. Monaghan; Naughton, Thomas J.; Sheridan, John T.

    2005-01-01

    We demonstrate an optical system that encodes two dimensional data as different polarization states. The encrypted image is recorded using a digital holographic setup and the decryption is done numerically.

  5. Fiber-Based Polarization Diversity Detection for Polarization-Sensitive Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Hamid Pahlevaninezhad

    2014-09-01

    Full Text Available We present a new fiber-based polarization diversity detection (PDD scheme for polarization sensitive optical coherence tomography (PSOCT. This implementation uses a new custom miniaturized polarization-maintaining fiber coupler with single mode (SM fiber inputs and polarization maintaining (PM fiber outputs. The SM fiber inputs obviate matching the optical lengths of the two orthogonal OCT polarization channels prior to interference while the PM fiber outputs ensure defined orthogonal axes after interference. Advantages of this detection scheme over those with bulk optics PDD include lower cost, easier miniaturization, and more relaxed alignment and handling issues. We incorporate this PDD scheme into a galvanometer-scanned OCT system to demonstrate system calibration and PSOCT imaging of an achromatic quarter-wave plate, fingernail in vivo, and chicken breast, salmon, cow leg, and basa fish muscle samples ex vivo.

  6. Random polarization dynamics in a resonant optical medium

    CERN Document Server

    Newhall, Katherine A; Kramer, Peter R; Kovacic, Gregor; Gabitov, Ildar R

    2013-01-01

    Random optical-pulse polarization switching along an active optical medium in the $\\Lambda$-configuration with spatially disordered occupation numbers of its lower energy sub-level pair is described using the idealized integrable Maxwell-Bloch model. Analytical results describing the light polarization-switching statistics for the single self-induced transparency pulse are compared with statistics obtained from direct Monte-Carlo numerical simulations.

  7. Optical characterization and polarization calibration for rigid endoscopes

    Science.gov (United States)

    Garcia, Missael; Gruev, Viktor

    2017-02-01

    Polarization measurements give orthogonal information to spectral images making them a great tool in the characterization of environmental parameters in nature. Thus, polarization imagery has proven to be remarkably useful in a vast range of biomedical applications. One such application is the early diagnosis of flat cancerous lesions in murine colorectal tumor models, where polarization data complements NIR fluorescence analysis. Advances in nanotechnology have led to compact and precise bio-inspired imaging sensors capable of accurately co-registering multidimensional spectral and polarization information. As more applications emerge for these imagers, the optics used in these instruments get very complex and can potentially compromise the original polarization state of the incident light. Here we present a complete optical and polarization characterization of three rigid endoscopes of size 1.9mm x 10cm (Karl Storz, Germany), 5mm x 30cm, and 10mm x 33cm (Olympus, Germany), used in colonoscopy for the prevention of colitis-associated cancer. Characterization results show that the telescope optics act as retarders and effectively depolarize the linear component. These incorrect readings can cause false-positives or false-negatives leading to an improper diagnosis. In this paper, we offer a polarization calibration scheme for these endoscopes based on Mueller calculus. By modeling the optical properties from training data as real-valued Mueller matrices, we are able to successfully reconstruct the initial polarization state acquired by the imaging system.

  8. Fast beam steering with full polarization control using a galvanometric optical scanner and polarization controller

    CERN Document Server

    Jofre, M; Steinlechner, F; Oliverio, N; Torres, J P; Pruneri, V; Mitchell, M W; 10.1364/OE.20.012247

    2012-01-01

    Optical beam steering is a key element in many industrial and scientific applications like in material processing, information technologies, medical imaging and laser display. Even though galvanometer-based scanners offer flexibility, speed and accuracy at a relatively low cost, they still lack the necessary control over the polarization required for certain applications. We report on the development of a polarization steerable system assembled with a fiber polarization controller and a galvanometric scanner, both controlled by a digital signal processor board. The system implements control of the polarization decoupled from the pointing direction through a feed-forward control scheme. This enables to direct optical beams to a desired direction without affecting its initial polarization state. When considering the full working field of view, we are able to compensate polarization angle errors larger than 0.2 rad, in a temporal window of less than $\\sim 20$ ms. Given the unification of components to fully cont...

  9. Local circular polarizations in nanostructures induced by linear polarization via optical near-fields

    CERN Document Server

    Naruse, Makoto; Inoue, Tetsuya; Yasuda, Hideki; Hori, Hirokazu; Naya, Masayuki

    2015-01-01

    We previously reported [Naruse, et al. Sci. Rep. 4, 6077, 2014] that the geometrical randomness of disk-shaped silver nanoparticles, which exhibit high reflection at near-infrared wavelengths, serves as the origin of a particle-dependent localization and hierarchical distribution of optical near-fields in the vicinity of the nanostructure. In this study, we show that the induced polarizations are circular, particularly at resonant wavelengths. We formulate optical near-field processes between nanostructures, accounting for their polarizations and geometries, and attribute circular polarization to the layout-dependent phase difference between the electrical susceptibilities associated with longitudinal and transverse-electric components. This study clarifies the fundamental optical properties of random nanostructured matter and offers generic theoretical concepts for implementing nanoscale polarizations of optical near-fields.

  10. Generation and propagation of radially polarized beams in optical fibers

    DEFF Research Database (Denmark)

    Ramachandran, Siddharth; Kristensen, P; Yan, M F

    2009-01-01

    Beams with polarization singularities have attracted immense recent attention in a wide array of scientific and technological disciplines. We demonstrate a class of optical fibers in which these beams can be generated and propagated over long lengths with unprecedented stability, even in the pres......Beams with polarization singularities have attracted immense recent attention in a wide array of scientific and technological disciplines. We demonstrate a class of optical fibers in which these beams can be generated and propagated over long lengths with unprecedented stability, even...... in the presence of strong bend perturbations. This opens the door to exploiting nonlinear fiber optics to manipulate such beams. This fiber also possesses the intriguingly counterintuitive property of being polarization maintaining despite being strictly cylindrically symmetric, a prospect hitherto considered...... infeasible with optical fibers. (C) 2009 Optical Society of America....

  11. Optical Realization of Deterministic Entanglement Concentration of Polarized Photons

    Institute of Scientific and Technical Information of China (English)

    GU Yong-Jian; XIAN Liang; LI Wen-Dong; MA Li-Zhen

    2008-01-01

    @@ We propose a scheme for optical realization of deterministic entanglement concentration of polarized photons.To overcome the difficulty due to the lack of sufficiently strong interactions between photons, teleportation is employed to transfer the polarization states of two photons onto the path and polarization states of a third photon, which is made possible by the recent experimental realization of the deterministic and complete Bell state measurement. Then the required positive operator-valued measurement and further operations can be implemented deterministically by using a linear optical setup. All these are within the reach of current technology.

  12. Tailored Optical Polarization in Nano-Structured Metamaterials

    CERN Document Server

    Mendoza, Bernardo S

    2016-01-01

    A very efficient method for the calculation of the effective optical response of nano-structured composite systems allows the design of metamaterials tailored for specific optical polarization properties. We use our method to design 2D periodic arrays of sub-wavelength dielectric inclusions within nanometric supported metallic thin films which behave as either an almost perfect linearly dichroic system, as a controllable source of circular polarized light, as a system with a large circular dichroism, or as a circular polarizer. All of these systems may be tuned over a wide energy range.

  13. Optical Monitoring of TeV Blazars

    Science.gov (United States)

    Carini, Michael T.; Barnaby, D.; Walters, R.; Maune, J.; Shakhovskoy, D.; Antonyuk, K.

    2007-12-01

    We present the results of long term optical monitoring of known and candidate TeV Blazars. These observations were obtained with the 0.6m telescope at the Bell Observatory of Western Kentucky University and the 1.3M AZT11 telescope at the Crimean Astrophysical Observatory. A total of 10 known TeV Blazars and 11 TeV Blazar candidates are being monitored. Some of the known TeV Blazars are being monitored as part of the Whipple 10m Blazar monitoring program. The recent success of Magic in detecting Blazars based on enhanced optical activity has resulted in us adding additional TeV candidate sources to our routine optical monitoring list. The detection of enhanced optical activity in these sources will then be used to trigger TeV observations.

  14. Circular polarization in the optical afterglow of GRB 121024A

    CERN Document Server

    Wiersema, K; Toma, K; van der Horst, A J; Varela, K; Min, M; Greiner, J; Starling, R L C; Tanvir, N R; Wijers, R A M J; Campana, S; Curran, P A; Fan, Y; Fynbo, J P U; Gorosabel, J; Gomboc, A; Gotz, D; Hjorth, J; Jin, Z P; Kobayashi, S; Kouveliotou, C; Mundell, C; O'Brien, P T; Pian, E; Rowlinson, A; Russell, D M; Salvaterra, R; Alighieri, S di Serego; Tagliaferri, G; Vergani, S D; Elliott, J; Farina, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovski, V; Willingale, R

    2014-01-01

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet, when measured minutes after the burst, and the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after burst in GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and negligable circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blastwave. Here we report the detection of circularly polarized optical light in the afterglow of GRB 121024A, measured 0.1...

  15. MASTER optical polarization variability detection in the Microquasar V404 Cyg/GS2023+33

    CERN Document Server

    Lipunov, Vladimir M; Kornilov, V; Krushinskiy, V; Vlasenko, D; Tiurina, N; Balanutsa, P; Kuznetsov, A; Budnev, N; Gress, O; Tlatov, A; Lopez, R Rebolo; Serra-Ricart, M; Buckley, D A H; Israelian, G; Lodieu, N; Ivanov, K; Yazev, S; Sergienko, Yu; Gabovich, A; Yurkov, V; Levato, H; Saffe, C; Podesta, R; Mallamaci, C; Lopez, C

    2016-01-01

    On 2015 June 15 the Swift space observatory discovered that the Galactic black hole candidate V404 Cyg was undergoing another active X-ray phase, after 25 years of inactivity (Barthelmy et al. 2015). Twelve telescopes of the MASTER Global Robotic Net located at six sites across four continents were the first ground based observatories to start optical monitoring of the microquasar after its gamma-ray wakeup at 18h 34m 09s U.T. on 2015 June 15 (Lipunov et al. 2015). In this paper we report, for the first time, the discovery of variable optical linear polarization, changing by 4-6% over a timescale of approximately 1 h, on two different epochs. We can conclude that the additional variable polarization arisies from the relativistic jet generated by the black hole in V404Cyg. The polarization variability correlates with optical brightness changes, increasing when the flux decreases.

  16. Polarization-Sensitive Quantum Optical Coherence Tomography: Experiment

    CERN Document Server

    Booth, Mark C; Teich, Malvin Carl

    2010-01-01

    Polarization-sensitive quantum optical coherence tomography (PS-QOCT) makes use of a Type-II twin-photon light source for carrying out optical sectioning with polarization sensitivity. A BBO nonlinear optical crystal pumped by a Ti:sapphire psec-pulsed laser is used to confirm the theoretical underpinnings of this imaging paradigm. PS-QOCT offers even-order dispersion cancellation with simultaneous access to the group-velocity dispersion characteristics of the interstitial medium between the reflecting surfaces of the sample.

  17. Steering optical comb frequency by rotating polarization state

    CERN Document Server

    Zhang, Y; Zhang, X F; Zhang, L; Han, W; Guo, W; Jiang, H; Zhang, S

    2016-01-01

    Optical frequency combs, with precise control of repetition rate and carrier-envelope-offset frequency, have revolutionized many fields, such as fine optical spectroscopy, optical frequency standards, ultra-fast science research, ultra-stable microwave generation and precise ranging measurement. However, existing high bandwidth frequency control methods have small dynamic range, requiring complex hybrid control techniques. To overcome this limitation, we develop a new approach, where a home-made intra-cavity electro-optic modulator tunes polarization state of laser signal rather than only optical length of the cavity, to steer frequencies of a nonlinear-polarization-rotation mode-locked laser. By taking advantage of birefringence of the whole cavity, this approach results in not only broadband but also relative large-dynamic frequency control. Experimental results show that frequency control dynamic range increase at least one order in comparison with the traditional intra-cavity electro-optic modulator techn...

  18. Precision measurement of the nuclear polarization in laser-cooled, optically pumped $^{37}\\mathrm{K}$

    CERN Document Server

    Fenker, Benjamin; Melconian, Dan; Anderson, Rhys M A; Anholm, Melissa; Ashery, Daniel; Behling, Richard S; Cohen, Iuliana; Craiciu, Ioana; Donohue, John M; Farfan, Christian; Friesen, Daniel; Gorelov, Alexandre; McNeil, James; Mehlman, Michael; Norton, Heather; Olchanski, Konstantin; Smale, Scott; Theriault, O; Vantyghem, Adrian N; Warner, Claire L

    2016-01-01

    We report a measurement of the nuclear polarization of laser-cooled, optically-pumped $^{37}\\mathrm{K}$ atoms which will allow us to precisely measure angular correlation parameters in the beta-decay of the same atoms. These results will be used to test the $V-A$ framework of the weak interaction at high precision. At the TRIUMF Neutral Atom Trap (TRINAT), a magneto-optical trap (MOT) confines and cools neutral $^{37}\\mathrm{K}$ atoms and optical pumping spin-polarizes them. We monitor the nuclear polarization of the same atoms that are decaying in situ by photoionizing a small fraction of the partially polarized atoms and then use the standard optical Bloch equations to model their population distribution. We obtain an average nuclear polarization of $P = 0.9913\\pm0.0008$, which is significantly more precise than previous measurements with this technique. Since our current measurement of the beta-asymmetry has $0.2\\%$ statistical uncertainty, the polarization measurement reported here will not limit its over...

  19. High-energy nuclear optics of polarized particles

    CERN Document Server

    Baryshevsky, Vladimir G

    2012-01-01

    The various phenomena caused by refraction and diffraction of polarized elementary particles in matter have opened up a new research area in the particle physics: nuclear optics of polarized particles. Effects similar to the well-known optical phenomena such as birefringence and Faraday effects, exist also in particle physics, though the particle wavelength is much less than the distance between atoms of matter. Current knowledge of the quasi-optical effects, which exist for all particles in any wavelength range (and energies from low to extremely high), will enable us to investigate different properties of interacting particles (nuclei) in a new aspect. This pioneering book will provide detailed accounts of quasi-optical phenomena in the particle polarization, and will interest physicists and professionals in experimental particle physics.

  20. A cryogenic optical feedthrough using polarization maintaining fibers.

    Science.gov (United States)

    Nelson, M J; Collins, C J; Speake, C C

    2016-03-01

    Polarization maintaining optical fibers can be used to transmit linearly polarized light over long distances but their use in cryogenic environments has been limited by their sensitivity to temperature changes and associated mechanical stress. We investigate experimentally how thermal stresses affect the polarization maintaining fibers and model the observations with Jones matrices. We describe the design, construction, and testing of a feedthrough and fiber termination assembly that uses polarization maintaining fiber to transmit light from a 633 nm HeNe laser at room temperature to a homodyne polarization-based interferometer in a cryogenic vacuum. We report on the efficiency of the polarization maintaining properties of the feedthrough assembly. We also report that, at cryogenic temperatures, the interferometer can achieve a sensitivity of 8 × 10(-10) rad/√Hz at 0.05 Hz using this feedthrough.

  1. Three Color Particle Optical Extinction Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design, build and test a multi-color (red, green, blue) particle optical extinction monitor suitable for use in either land or airborne applications....

  2. Measurements of optical polarization properties in dental tissues and biomaterials

    Science.gov (United States)

    Fernández-Oliveras, Alicia; Pecho, Oscar E.; Rubiño, Manuel; Pérez, María M.

    2011-05-01

    Since biological tissues can have the intrinsic property of altering the polarization of incident light, optical polarization studies are important for a complete characterization. We have measured the polarized light scattered off of different dental tissues and biomaterials for a comparative study of their optical polarization property. The experimental setup was composed by a He-Ne laser, two linear polarizers and a detection system based on a photodiode. The laser beam was passed through one linear polarizer placed in front of the sample, beyond which the second linear polarizer (analyzer) and the photodiode detector were placed. First, the maximum laser-light intensity (reference condition) was attained without the sample in the laser path. Then, the sample was placed between the two polarizers and the polarization shift of the scattered laser light was determined by rotating the analyzer until the reference condition was reached. Two dental-resin composites (nanocomposite and hybrid) and two human dental tissues (enamel and dentine) were analyzed under repeatability conditions at three different locations on the sample: 20 measurements of the shift were taken and the average value and the uncertainty associated were calculated. For the human dentine the average value of the polarization shift found was 7 degrees, with an associated uncertainty of 2 degrees. For the human enamel and both dental-resin composites the average shift values were found to be similar to their corresponding uncertainties (2 degrees). The results suggest that although human dentine has notable polarization properties, dental-resin composites and human enamel do not show significant polarization shifts.

  3. Automated control of optical polarization for nonlinear microscopy

    Science.gov (United States)

    Brideau, Craig; Stys, Peter K.

    2012-03-01

    Laser-scanning non-linear optical techniques such as multi-photon fluorescence excitation microscopy (MPM), Second/ Third Harmonic Generation (SHG/THG), and Coherent Anti-Stokes Raman Scattering (CARS) are being utilized in research laboratories worldwide. The efficiencies of these non-linear effects are dependent on the polarization state of the excitation light relative to the orientation of the sample being imaged. In highly ordered anisotropic biological samples this effect can become pronounced and the excitation polarization can have a dramatic impact on imaging experiments. Therefore, controlling the polarization state of the exciting light is important; however this is challenging when the excitation light passes through a complex optical system. In a typical laser-scanning microscope, components such as the dichroic filters, lenses, and even mirrors can alter the polarization state of a laser beam before it reaches the sample. We present an opto-mechanical solution to compensate for the polarization effects of an optical path, and to precisely program the polarization state of the exciting laser light. The device and accompanying procedures allow the delivery of precise laser polarization states at constant average power levels to a sample during an imaging experiment.

  4. Optics Technologies for LUVOIR & HabEx: Polarization & Mirror Count

    Science.gov (United States)

    Breckinridge, James B.

    2017-01-01

    We show that polarization aberrations and mirror count will limit the optical system performance of LUVOIR and HabEx and thus both their exoplanet science yield and their UV science. In addition we show how increased mirror count reduces optical system transmittance and increases cost in large aperture telescopes. We make the observation that orthogonally polarized light does not interfere to form an intensity image. We show how the two polarization aberrations (diattenuation & and retardance) distort the system PSF, decrease transmittance, and increase the unwanted background above that predicted using scalar models. An optical system corrected for geometric path difference errors is a necessary but not sufficient condition for the perfect image formation needed to directly image terrestrial exoplanets. Geometric (trigonometric) path difference errors are controlled using adaptive optics (tip-tilt & wavefront), active metrology and precision pointing. However, image quality is also determined by several physical optics factors: diffraction, polarization, partial coherence, and chromatism all of which degrade image quality and are not corrected through the control of geometric path difference. The source of physical optics errors lies in the opto-mechanical packaging of optical elements, masks, stops and the thin film coatings needed to obtain high transmittance. Adaptive optics corrects wavefront errors described by geometric or optical path length errors but not those wavefront errors introduced by physical optics. We show that for large telescopes each reflection costs over $100 million to increase the collecting area in order to recover lost SNR. Examples will be shown. The LUVOIR and HabEx systems will need fewer optical surfaces than current systems

  5. Structural health monitoring with fiber optic sensors

    Institute of Scientific and Technical Information of China (English)

    F.ANSARI

    2009-01-01

    Optical fiber sensors have been successfully implemented in aeronautics, mechanical systems, and medical applications. Civil structures pose further challenges in monitoring mainly due to their large dimensions, diversity and heterogeneity of materials involved, and hostile construction environment. This article provides a summary of basic principles pertaining to practical health monitoring of civil engineering structures with optical fiber sensors. The issues discussed include basic sensor principles, strain transfer mechanism, sensor packaging, sensor placement in construction environment, and reliability and survivability of the sensors.

  6. Optically enhanced nuclear cross polarization in acridine-doped fluorene

    Energy Technology Data Exchange (ETDEWEB)

    Oshiro, C.M.

    1982-06-01

    The objective of this work has been to create large polarizations of the dilute /sup 13/C nuclei in the solid state. The idea was to create /sup 1/H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the /sup 13/C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large /sup 1/H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large /sup 13/C polarizations have been created in fluorene single crystals. These large /sup 13/C polarizations have permitted the determination of the seven incongruent chemical shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined.

  7. Polarization Dependence of Linewidth Enhancement Factor in Semiconductor Optical Amplifier and Its Implication for Nonlinear Polarization Rotation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shuang; WU Chong-Qing; WANG Yong-Jun

    2009-01-01

    Linewidth enhancement factors (LEFs) of the transverse electric mode and the transverse magnetic mode in bulk semiconductor optical amplifiers are measured using the nonlinear optical loop mirror method and the principal state of polarization vector method.The polarization dependence of LEFs plays an important role in the nonlinear polarization rotation.The relationship between the polarization-dependence of LEFs and nonlinear polarization rotation in the Stokes space is demonstrated.

  8. Polarization holographic optical recording of a new photochromic diarylethene

    Science.gov (United States)

    Pu, Shouzhi; Miao, Wenjuan; Chen, Anyin; Cui, Shiqiang

    2008-12-01

    A new symmetrical photochromic diarylethene, 1,2-bis[2-methyl-5-(3-methoxylphenyl)-3-thienyl]perfluorocyclopentene (1a), was synthesized, and its photochromic properties were investigated. The compound exhibited good photochromism both in solution and in PMMA film with alternating irradiation by UV/VIS light, and the maxima absorption of its closed-ring isomer 1b are 582 and 599 nm, respectively. Using diarylethene 1b/PMMA film as recording medium and a He-Ne laser (633 nm) for recording and readout, four types of polarization and angular multiplexing holographic optical recording were performed perfectly. For different types of polarization recording including parallel linear polarization recording, parallel circular polarization recording, orthogonal linear polarization recording and orthogonal circular polarization recording,have been accomplished successfully. The results demonstrated that the orthogonal circular polarization recording is the best method for polarization holographic optical recording when this compound was used as recording material. With angular multiplexing recording technology, two high contrast holograms were recorded in the same place on the film with the dimension of 0.78 μm2.

  9. The Electro-Optic Beam Position Monitor

    CERN Document Server

    Doherty, James

    2013-01-01

    This reports outlines the development of a new ultra-wideband electro-optic beam position monitor (EO-BPM) for use in the Large Hadron Collider (LHC) which utilises birefringent crystals and the Pockels effect to monitor beam position. The physical principles behind the operation of the device and tested topology, which incorporates two Lithium Tantalate crystals, is discussed.

  10. Optical Observations Of Fermi LAT Monitored Blazars

    Science.gov (United States)

    Cook, Kyle; Carini, M. T.

    2009-01-01

    For the past 8 years the Bell Observatory at Western Kentucky University has been conducting R band monitoring of the variability of approximately 50 Blazars. A subset of these objects are being routinely observed with the LAT instrument on-board the Fermi Space Telescope. Adding the Robotically Controlled Telescope (RCT) at Kitt Peak National Observatory and observations with the AZT-11 telescope at the Crimean Astrophysical Observatory (CRAO), we are intensively monitoring the Blazars on the Lat monitoring list. We present the results of our long term monitoring of the LAT monitored Blazars, as well as the recent contemporaneous optical R band observations we have obtained of the LAT Blazars.

  11. Propagation of Optical Pulses in Polarization Maintaining Highly Birefringent Fibers

    Science.gov (United States)

    Leiva, Ariel; Olivares, Ricardo

    2008-04-01

    The propagation of Gaussian optical pulses through optical PM-HiBi (Polarization Maintaining Highly Birefringent) fibers is analyzed and simulated. Based upon a model of propagation as described by Marcuse, et al., [1] and Sunnerud, et al., [2], and the use of PMD (Polarization Mode Dispersion) compensators and emulators used by Kogelnik, et al. [2], [3] and Lima, et al. [4], we construct a simple model that allows graphical representation of the distortion experienced by optical pulses when propagating in a PM-HiBi fiber for different initial polarizations. The results of our analysis have the benefit of being identical to the more elaborate models of [1], [2], while also providing the additional advantage of simple graphical representation.

  12. Experimental observation of polarization-dependent optical vortex beams

    CERN Document Server

    Srisuphaphon, S; Photia, T; Temnuch, W; Chiangga, S; Deachapunya, S

    2016-01-01

    We report the experimental demonstration of the induced polarization-dependent optical vortex beams. We use the Talbot configuration as a method to probe this effect. In particular, our simple experiment shows the direct measurement of this observation. Our experiment can exhibit clearly the combination between the polarization and orbital angular momentum (OAM) states of light. This implementation might be useful for further studies in the quantum system or quantum information.

  13. Dynamics of dual-polarization VCSEL-based optical frequency combs under optical injection locking.

    Science.gov (United States)

    Prior, E; de Dios, C; Criado, R; Ortsiefer, M; Meissner, P; Acedo, P

    2016-09-01

    The present experimental work studies the dynamics of dual-polarization optical frequency combs (OFCs) based on gain switching (GS) vertical-cavity surface-emitting laser (VCSEL) diodes under optical injection locking (OIL). This study presents two main results. First, we have obtained an overall comb formed by two orthogonally polarized sub-combs with comparable span and power. The overall comb shows enhanced optical span and flatness and high coherence between its modes. The second result is that we have been able to control the polarization state of the overall comb by tuning the polarization state of the injected light by locking the same single teeth of the comb. This produces an overall comb with single polarization that is parallel or orthogonal. These are novel findings that provide for the development of efficient and compact OFCs based on GS VCSEL sources with versatile polarization dynamics.

  14. Complex polarization ratio to determine polarization properties of anisotropic tissue using polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Park, Jesung; Kemp, Nate J; Rylander, H Grady; Milner, Thomas E

    2009-08-03

    Complex polarization ratio (CPR) in materials with birefringence and biattenuance is shown as a logarithmic spiral in the complex plane. A multi-state Levenberg-Marquardt nonlinear fitting algorithm using the CPR trajectory collected by polarization sensitive optical coherence tomography (PS-OCT) was developed to determine polarization properties of an anisotropic scattering medium. The Levenberg-Marquardt nonlinear fitting algorithm using the CPR trajectory is verified using simulated PS-OCT data with speckle noise. Birefringence and biattenuance of a birefringent film, ex-vivo rodent tail tendon and in-vivo primate retinal nerve fiber layer were determined using measured CPR trajectories and the Levenberg-Marquardt nonlinear fitting algorithm.

  15. Circular polarization in the optical afterglow of GRB 121024A

    DEFF Research Database (Denmark)

    Wiersema, K.; Covino, S.; Toma, K.

    2014-01-01

    of the jet, when measured minutes after the burst, and the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after burst in GRB 120308A indicate the presence of large-scale ordered magnetic fields...... originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and negligable circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium...

  16. Optical Networks for Cost Monitoring and Reduction

    Directory of Open Access Journals (Sweden)

    R Buvanesvari

    2011-03-01

    Full Text Available This paper focuses on cost reduction and monitoring in optical networks. Optical mesh networks are cost savings with switching systems that are interconnected by point-to-point networks. Transponders play a major role in it. All-optical packet switching has been intensively investigated in recent years as an alternative to static, cross connect based networks. Several switch architectures have been proposed, all of them using buffers made of fiber delay lines. We consider the problem of minimizing the congestion in wireless optical (FSO backbone networks by placing controllable relay nodes. We propose algorithms for placement of relays in the network under node interface constraints. Further reduction in cost is done by the conversion of optical to electrical at the intermediate nodes. Optical transport networks offer a new level of flexibility in the optical layer allowing various services and thereby improving the efficiency, performance and robustness. An optical path with a transparent feature allows the transmission of signals that are optical and also independent of data rate and modulation format. Client layer protocol provides transparency for the transport layer in optical networks. Thus there is a significant challenge in terms of function, flexibility and monitoring cost.

  17. Polarized Raman optical activity of menthol and related molecules

    Science.gov (United States)

    Barron, L. D.; Hecht, L.; Blyth, S. M.

    1989-01-01

    Polarized and depolarized Raman optical activity spectra of menthol, menthyl chloride, neomenthol and neothiomenthol from 800 to 1500 cm -1 are reported. Despite axial symmetry in all the bonds, the presence of the heteroatoms O or S seems to induce large deviations from the expected ratio of 2:1 between the polarized and depolarized Raman optical activity intensities, but Cl does not. These deviations might originate in large electric quadrupole contributions induced by excited state interactions involving O or S Rydberg p orbitals and valence orbitals on other parts of the molecule. Such interactions appear to undermine the bond polarizability theory of Raman intensities.

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

    Science.gov (United States)

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

    2016-04-01

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

  19. Polarization nonreciprocity suppression of dual-polarization fiber-optic gyroscope under temperature variation.

    Science.gov (United States)

    Lu, Ping; Wang, Zinan; Luo, Rongya; Zhao, Dayu; Peng, Chao; Li, Zhengbin

    2015-04-15

    Polarization nonreciprocity (PN) is one of the most critical factors that degrades the performance of interferometric fiber-optic gyroscopes (IFOGs), particularly under varying temperature. We present an experimental investigation of PN error suppression in a dual-polarization IFOG. Both experimental results and theoretical analysis indicate that the PN errors of the two orthogonally polarized light waves always have opposite signs that can be effectively compensated despite the temperature variation. As a result, the long-term stability of the IFOG has been significantly improved. This study is promising for reducing the temperature fragility of IFOGs.

  20. Coherent control of optical polarization effects in metamaterials

    Science.gov (United States)

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

    2015-01-01

    Processing of photonic information usually relies on electronics. Aiming to avoid the conversion between photonic and electronic signals, modulation of light with light based on optical nonlinearity has become a major research field and coherent optical effects on the nanoscale are emerging as new means of handling and distributing signals. Here we demonstrate that in slabs of linear material of sub-wavelength thickness optical manifestations of birefringence and optical activity (linear and circular birefringence and dichroism) can be controlled by a wave coherent with the wave probing the polarization effect. We demonstrate this in proof-of-principle experiments for chiral and anisotropic microwave metamaterials, where we show that the large parameter space of polarization characteristics may be accessed at will by coherent control. Such control can be exerted at arbitrarily low intensities, thus arguably allowing for fast handling of electromagnetic signals without facing thermal management and energy challenges. PMID:25755071

  1. Swept source/Fourier domain polarization sensitive optical coherence tomography with a passive polarization delay unit.

    Science.gov (United States)

    Baumann, Bernhard; Choi, WooJhon; Potsaid, Benjamin; Huang, David; Duker, Jay S; Fujimoto, James G

    2012-04-23

    Polarization sensitive optical coherence tomography (PS-OCT) is a functional imaging method that provides additional contrast using the light polarizing properties of a sample. This manuscript describes PS-OCT based on ultrahigh speed swept source / Fourier domain OCT operating at 1050 nm at 100 kHz axial scan rates using single mode fiber optics and a multiplexing approach. Unlike previously reported PS-OCT multiplexing schemes, the method uses a passive polarization delay unit and does not require active polarization modulating devices. This advance decreases system cost and avoids complex synchronization requirements. The polarization delay unit was implemented in the sample beam path in order to simultaneously illuminate the sample with two different polarization states. The orthogonal polarization components for the depth-multiplexed signals from the two input states were detected using dual balanced detection. PS-OCT images were computed using Jones calculus. 3D PS-OCT imaging was performed in the human and rat retina. In addition to standard OCT images, PS-OCT images were generated using contrast form birefringence and depolarization. Enhanced tissue discrimination as well as quantitative measurements of sample properties was demonstrated using the additional contrast and information contained in the PS-OCT images.

  2. Optical Performance Monitoring using Proactive Monitoring and the Time Caliper Method

    Science.gov (United States)

    Luk, Hon Tung

    The widespread real time multimedia applications generate increasing demands of data transmission capacity nowadays. Fiber-optic communication is the core technology to meet the capacity requirements of the fast growing internet data and to support the long haul transmission with low cost. Reliability is a key issue for high data rate transmission systems because the interruption of connection may result in substantial amount of data lost. Performance monitoring is essential for maintaining reliability by keeping track of the network status rapidly. In this thesis, we will investigate two aspects of performance monitoring in optical communication systems: network-based monitoring and link-based physical layer monitoring. In the case of network-based monitoring, proactive monitoring is used to reduce the acquisition time to obtain the monitoring information. The monitoring process is modeled as a Markov Decision Process. We propose nine different monitoring schemes and show that the scheme with increasing probing number and probing unpopular edge first has the best overall performance, regarding to coverage of monitoring links and blocking probability. On the other hand, if we would like to reduce the cost for proactive monitoring, the shortest path probing scheme is the optimal monitoring schemes when the monitoring paths are probed independently. In addition, if we consider the cases of edge overlapping and node overlapping of the monitoring paths, the overlapping probing scheme may require less number of hops during the monitoring process. Formulas have been derived for checking the conditions when the overlapping probing scheme can be applied. Simulations are performed under different optical network topologies and conditions to evaluate the performance of the schemes. Measurement of relative delay facilitates various monitoring and compensation applications, such as synchronization of subchannels in multiplexing systems, dispersion measurement. In the case of

  3. 160-Gb/s polarization-multiplexing optical NRZ-DQPSK transmission using differential detection

    Institute of Scientific and Technical Information of China (English)

    He Wen; Jinxin Liao; Xiaoping Zheng; Hanyi Zhang

    2011-01-01

    Using differential detection,we perform polarization-multiplexing 160-Gb/s optical non-return-to-zero (NRZ) differential quadrature phase shift keying (DQPSK) signal transmission over 100-km standard single mode fiber at a bit error rate (BER) of less than 10-9.The enabling technology includes clock recovery,fine dispersion compensation,and polarization tracking for de-multiplexing.Furthermore,a hybrid clock recovery scheme is proposed.The scheme is realized with ordinary devices using an optoelectrical modulator to down-convert the clock frequency and a phase-locked loop for filtering,which can provide an indication signal that simultaneouslv monitors residual disoersion and tracking polarization.Given the ever increasing bandwidth demands (e.g.,for imaging,demand of video,gaming,etc.),the capacity of optical transmission systems is being constantly raised through the application of several approaches that include the use of advanced modulation formats with higher spectral efficiency,increasing the symbol rate of each channel,and orthogonal polarization multiplexing with idcntical wavelengths;these approaches are enabled by coherent detection[1-3].%Using differential detection, we perform polarization-multiplexing 160-Gb/s optical non-return-to-zero (NRZ) differential quadrature phase shift keying (DQPSK) signal transmission over 100-km standard single mode fiber at a bit error rate (BER) of less than 10~9. The enabling technology includes clock recovery, fine dispersion compensation, and polarization tracking for de-multiplexing. Furthermore, a hybrid clock recovery scheme is proposed. The scheme is realized with ordinary devices using an optoclectrical modulator to down-convert the clock frequency and a phase-locked loop for filtering, which can provide an indication signal that simultaneously monitors residual dispersion and tracking polarization.

  4. Novaya Zemlya bora and polar cyclones in spaceborne SAR and optical imagery

    Science.gov (United States)

    Ivanov, A. Yu.

    2016-12-01

    Mesoscale meteorological phenomena, such as Novaya Zemlya bora and polar cyclones, have been studied based on the respective signatures in synthetic aperture radar (SAR) images of the sea surface using remote sensing methods. The local bora covers both coastal and open-sea zones of the Barents Sea to the west of Novaya Zemlya and can lead to catastrophic consequences in coastal waters of the archipelago. Another interesting and hardly predictable phenomenon is polar cyclones. The development of especially intensive and catastrophic polar cyclones can be traced using multisensor and multispectral imagery. It has been shown that the application of spaceborne SARs and optical sensors enables real time detection, forecast, and monitoring of Novaya Zemlya bora and polar cyclones in the Barents Sea, giving ground for their detail research.

  5. Three-dimensional polarization aberration functions in optical system based on three-dimensional polarization ray-tracing calculus

    Science.gov (United States)

    He, Wenjun; Fu, Yuegang; Liu, Zhiying; Zhang, Lei; Wang, Jiake; Zheng, Yang; Li, Yahong

    2017-03-01

    The polarization aberrations of a complex optical system with multi-element lens have been investigated using a 3D polarization aberration function. The 3D polarization ray-tracing matrix has been combined with the optical path difference to obtain a 3D polarization aberration function, which avoids the need for a complicated phase unwrapping process. The polarization aberrations of a microscope objective have been analyzed to include, the distributions of 3D polarization aberration functions, diattenuation aberration, retardance aberration, and polarization-dependent intensity on the exit pupil. Further, the aberrations created by the field of view and the coating on the distribution rules of 3D polarization aberration functions are discussed in detail. Finally a novel appropriate field of view and wavelength correction is proposed for a polarization aberration function which optimizes the image quality of a multi-element optical system.

  6. Stress engineering and the applications of inhomogeneously polarized optical fields

    Institute of Scientific and Technical Information of China (English)

    Thomas G. BROWN; Amber M. BECKLEY

    2013-01-01

    Spatial inhomogeneities in the polarization of a light field can show fascinating effects in focusing, propagation, illumination, and imaging. This paper provides examples of these effects and describes how deterministic stress on the periphery of an optical element can be used in fundamental studies of beam propagation, as well as applications such as polarimetry.

  7. Microwave-mediated magneto-optical trap for polar molecules

    Science.gov (United States)

    Dizhou, Xie; Wenhao, Bu; Bo, Yan

    2016-05-01

    Realizing a molecular magneto-optical trap has been a dream for cold molecular physicists for a long time. However, due to the complex energy levels and the small effective Lande g-factor of the excited states, the traditional magneto-optical trap (MOT) scheme does not work very well for polar molecules. One way to overcome this problem is the switching MOT, which requires very fast switching of both the magnetic field and the laser polarizations. Switching laser polarizations is relatively easy, but fast switching of the magnetic field is experimentally challenging. Here we propose an alternative approach, the microwave-mediated MOT, which requires a slight change of the current experimental setup to solve the problem. We calculate the MOT force and compare it with the traditional MOT and the switching MOT scheme. The results show that we can operate a good MOT with this simple setup. Project supported by the Fundamental Research Funds for the Central Universities of China.

  8. Normalized Stokes operators for polarization correlations of entangled optical fields

    Science.gov (United States)

    Żukowski, Marek; Laskowski, Wiesław; Wieśniak, Marcin

    2017-04-01

    Stokes parameters are a standard tool in quantum optics. They involve averaged intensities at exits of polarizers. If the overall measured intensity fluctuates, as, e.g., for states with undefined photon numbers, the instances of its increased value contribute more to the parameters. One can introduce normalized quantum Stokes operators. Operationally, for a given single run of the experiment, their values are differences of measured intensities (or photon numbers) at the two exits of a polarizer divided by their sum. Effects of intensity fluctuations are removed. Switching to normalized Stokes operators results in more sensitive entanglement conditions. We also show a general method of deriving an entanglement indicator for optical fields which use polarization correlations, which starts with any two-qubit entanglement witness. This allows one to vastly expand the family of such indicators.

  9. Fiber-optic polarization diversity detection for rotary probe optical coherence tomography.

    Science.gov (United States)

    Lee, Anthony M D; Pahlevaninezhad, Hamid; Yang, Victor X D; Lam, Stephen; MacAulay, Calum; Lane, Pierre

    2014-06-15

    We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states when imaging with rotating fiber optic probes in Intralipid suspension and during in vivo imaging of human airways.

  10. Discovery of Optical Circular Polarization of the Crab Pulsar

    Science.gov (United States)

    Wiktorowicz, Sloane; Ramirez-Ruiz, Enrico; Illing, Rainer M. E.; Nofi, Larissa

    2015-01-01

    Nearly 50 years ago at the Lick 3-m Shane telescope, Wampler et al. (1969) discovered optical linear depolarization of the Crab pulsar's main pulse and interpulse regions, which led to the interpretation of synchrotron radiation as the source of pulsed emission. We present phase-resolved, simultaneous linear and circular polarization of the Crab pulsar using the POLISH2 aperture-integrated, optical polarimeter at the Lick 3-m telescope. The two photoelastic modulators in this instrument, used instead of waveplates, AC couple incident Stokes Q, U, and V to unique, independent frequencies between 10 and 200 kHz. Stokes I is measured from the time-averaged intensity of the beam. Thus, this instrument is capable of simultaneous measurement of Q/I, U/I, and V/I in 20 microsecond temporal bins with part-per-million nightly sensitivity on naked eye stars. From just one hour of observations, we confirm linear depolarization of the main pulse and interpulse regions, and we also discover significant optical circular polarization at all pulsar phases. Furthermore, we observe circular depolarization of the main pulse and interpulse regions with respect to the off-pulse region. Observations of strongly polarized calibration stars, as well as lamp observations with a linear polarizer inserted upstream of the modulators, demonstrate that circular polarization results obtained on the Crab pulsar are not due to spurious, instrumental conversion of linear to circular polarization. Therefore, using novel instrumentation, our observations shed new light on this enigmatic object, and we demonstrate that the Lick 3-m Shane telescope still remains at the cutting edge for optical polarimetry.

  11. A transflective nano-wire grid polarizer based fiber-optic sensor.

    Science.gov (United States)

    Feng, Jing; Zhao, Yun; Lin, Xiao-Wen; Hu, Wei; Xu, Fei; Lu, Yan-Qing

    2011-01-01

    A transflective nano-wire grid polarizer is fabricated on a single mode fiber tip by focused ion beam machining. In contrast to conventional absorptive in-line polarizers, the wire grids reflect TE-mode, while transmitting TM-mode light so that no light power is discarded. A reflection contrast of 13.7 dB and a transmission contrast of 4.9 dB are achieved in the 1,550 nm telecom band using a 200-nm wire grid fiber polarizer. With the help of an optic circulator, the polarization states of both the transmissive and reflective lights in the fiber may be monitored simultaneously. A kind of robust fiber optic sensor is thus proposed that could withstand light power variations. To verify the idea, a fiber pressure sensor with the sensitivity of 0.24 rad/N is demonstrated. The corresponding stress-optic coefficient of the fiber is measured. In addition to pressure sensing, this technology could be applied in detecting any polarization state change induced by magnetic fields, electric currents and so on.

  12. A Transflective Nano-Wire Grid Polarizer Based Fiber-Optic Sensor

    Directory of Open Access Journals (Sweden)

    Yan-Qing Lu

    2011-02-01

    Full Text Available A transflective nano-wire grid polarizer is fabricated on a single mode fiber tip by focused ion beam machining. In contrast to conventional absorptive in-line polarizers, the wire grids reflect TE-mode, while transmitting TM-mode light so that no light power is discarded. A reflection contrast of 13.7 dB and a transmission contrast of 4.9 dB are achieved in the 1,550 nm telecom band using a 200-nm wire grid fiber polarizer. With the help of an optic circulator, the polarization states of both the transmissive and reflective lights in the fiber may be monitored simultaneously. A kind of robust fiber optic sensor is thus proposed that could withstand light power variations. To verify the idea, a fiber pressure sensor with the sensitivity of 0.24 rad/N is demonstrated. The corresponding stress-optic coefficient of the fiber is measured. In addition to pressure sensing, this technology could be applied in detecting any polarization state change induced by magnetic fields, electric currents and so on.

  13. Reusable rocket engine optical condition monitoring

    Science.gov (United States)

    Wyett, L.; Maram, J.; Barkhoudarian, S.; Reinert, J.

    1987-01-01

    Plume emission spectrometry and optical leak detection are described as two new applications of optical techniques to reusable rocket engine condition monitoring. Plume spectrometry has been used with laboratory flames and reusable rocket engines to characterize both the nominal combustion spectra and anomalous spectra of contaminants burning in these plumes. Holographic interferometry has been used to identify leaks and quantify leak rates from reusable rocket engine joints and welds.

  14. Trapping polarization of light in nonlinear optical fibers: An ideal Raman polarizer

    CERN Document Server

    Kozlov, Victor V; Ania-Castanon, Juan Diego; Wabnitz, Stefan

    2012-01-01

    The main subject of this contribution is the all-optical control over the state of polarization (SOP) of light, understood as the control over the SOP of a signal beam by the SOP of a pump beam. We will show how the possibility of such control arises naturally from a vectorial study of pump-probe Raman interactions in optical fibers. Most studies on the Raman effect in optical fibers assume a scalar model, which is only valid for high-PMD fibers (here, PMD stands for the polarization-mode dispersion). Modern technology enables manufacturing of low-PMD fibers, the description of which requires a full vectorial model. Within this model we gain full control over the SOP of the signal beam. In particular we show how the signal SOP is pulled towards and trapped by the pump SOP. The isotropic symmetry of the fiber is broken by the presence of the polarized pump. This trapping effect is used in experiments for the design of new nonlinear optical devices named Raman polarizers. Along with the property of improved sig...

  15. Twisted optical metamaterials for planarized ultrathin broadband circular polarizers.

    Science.gov (United States)

    Zhao, Y; Belkin, M A; Alù, A

    2012-05-29

    Optical metamaterials are usually based on planarized, complex-shaped, resonant nano-inclusions. Three-dimensional geometries may provide a wider set of functionalities, including broadband chirality to manipulate circular polarization at the nanoscale, but their fabrication becomes challenging as their dimensions get smaller. Here we introduce a new paradigm for the realization of optical metamaterials, showing that three-dimensional effects may be obtained without complicated inclusions, but instead by tailoring the relative orientation within the lattice. We apply this concept to realize planarized, broadband bianisotropic metamaterials as stacked nanorod arrays with a tailored rotational twist. Because of the coupling among closely spaced twisted plasmonic metasurfaces, metamaterials realized with conventional lithography may effectively operate as three-dimensional helical structures with broadband bianisotropic optical response. The proposed concept is also shown to relax alignment requirements common in three-dimensional metamaterial designs. The realized sample constitutes an ultrathin, broadband circular polarizer that may be directly integrated within nanophotonic systems.

  16. Wide-field monitoring strategy for the study of fast optical transients

    Science.gov (United States)

    Beskin, Grigory; Bondar, Sergey; Karpov, Sergey; Guarnieri, Adriano; Bartolini, Corrado; Greco, Giuseppe; Piccioni, Adalberto

    2010-10-01

    We discuss the strategy of search for fast optical transients accompanying gamma-ray bursts by means of continuous monitoring of wide sky fields with high temporal resolution. We describe the design, performance and results of our cameras, FAVOR and TORTORA. Also we discuss the perspectives of this strategy and possible design of next-generation equipment for wide-field monitoring which will be able to detect optical transients and to study their color and polarization properties with high time resolution.

  17. Optical characteristic variations in gamma ray irradiated polarization-maintaining optical fibers

    Science.gov (United States)

    Yokota, Hirohisa; Kameda, Yosuke; Imai, Yoh

    2017-02-01

    Polarization-maintaining (PM) optical fibers are introduced in fiber optic communication systems and optical fiber sensors to improve their performances. It is known that characteristics of optical fibers vary for radiation exposures, e.g., a transmission loss increment. It is important to clarify the characteristic variations of PM fibers by radiations in their applications. The radiation induced optical characteristic variation is also useful for an application of optical fibers including PM fibers as radiation sensors. In this paper, optical characteristic variations in gamma ray irradiated PM optical fibers with low modal birefringence were experimentally clarified indenting to apply a polarization optical time domain reflectometry to a distributed radiation sensor. It was confirmed that the transmission losses for both polarization modes in elliptical jacket fibers increased similar to ordinary silica based single-mode fibers, where the difference of transmission losses of two polarization modes was enhanced by the irradiation. We also clarified that the modal birefringence of the elliptical jacket fibers increased for the irradiation for the first time by the beat length measurement using the wavelength sweeping technique.

  18. THE DIFFERENCE OF OPTICAL POLARIZATION PROPERTIES BETWEEN XBLs AND RBLs

    Institute of Scientific and Technical Information of China (English)

    XIE GUANG-ZHONG; MEI DONG-CHENG; DAI BEN-ZHONG

    2001-01-01

    On the basis of the beaming model, we have derived a relation between the observed polarization (Pob) and Doppler-corrected optical magnitude (mcorr), logPob = 0.4(1 - k)mkcorr+ C. We tested the correlation between Pob and mcorr. The main results are as follows: (1) for both high and low states, there are strong correlations between Pob and mcorr for 29 RBLs with well-observed polarization and Doppler factor, where mcorr = mob + (3 + α) log δ/0.4, and δ is the optical Doppler factor; (2) no correlation exists between Pob and the observed optical magnitude, mob, for the 29 RBLs in high state, but there is a close correlation for the 29 RBLs in low state; (3) however, there is an obvious anti-correlation between Pob and mcorr for 35 XBLs with good simultaneous observation data. Our results show that (i) a new difference in polarization is found between RBLs and XBLs; (ii) this difference in polarization between RBLs and XBLs seems really to be physical differences.

  19. Investigation of Polarization-Dependent Optical Force in Optical Tweezers using Generalized Lorenz-Mie Theory

    CERN Document Server

    Choi, Jai-Min

    2015-01-01

    In vectorial diffraction theory, tight focusing of a linearly polarized laser beam produces an anisotropic field distribution around the focal plane. We present a numerical investigation of the electromagnetic field distribution of a focused beam in terms of the input beam polarization state and the associated effects on the trap stiffness asymmetry of optical tweezers. We also explore the symmetry change of a polarization-dependent optical force due to the electromagnetic field redistribution by the presence of dielectric spheres of selected diameters ranging from the Rayleigh scattering regime to the Mie scattering regime.

  20. Primate retina imaging with polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Ducros, Mathieu G.; Marsack, Jason D.; Rylander, H. Grady; Thomsen, Sharon L.; Milner, Thomas E.

    2001-12-01

    Polarization-sensitive optical coherence tomography (PSOCT) is applied to determine the depth-resolved polarization state of light backreflected from the eye. The birefringence of the retinal nerve fiber layer (RNFL) was observed and measured from PSOCT images recorded postmortem in a Rhesus monkey. An image-processing algorithm was developed to identify birefringent regions in acquired PSOCT retinal images and automatically determine the thickness of the RNFL. Values of the RNFL thickness determined from histology and PSOCT were compared. PSOCT may provide a new method to determine RNFL thickness and birefringence for glaucoma diagnostics.

  1. D-Shaped Polarization Maintaining Fiber Sensor for Strain and Temperature Monitoring

    Science.gov (United States)

    Qazi, Hummad Habib; Mohammad, Abu Bakar; Ahmad, Harith; Zulkifli, Mohd Zamani

    2016-01-01

    A D-shaped polarization-maintaining fiber (PMF) as fiber optic sensor for the simultaneous monitoring of strain and the surrounding temperature is presented. A mechanical end and edge polishing system with aluminum oxide polishing film is utilized to perform sequential polishing on one side (lengthwise) of the PMF in order to fabricate a D-shaped cross-section. Experimental results show that the proposed sensor has high sensitivity of 46 pm/µε and 130 pm/°C for strain and temperature, respectively, which is significantly higher than other recently reported work (mainly from 2013) related to fiber optic sensors. The easy fabrication method, high sensitivity, and good linearity make this sensing device applicable in various applications such as health monitoring and spatial analysis of engineering structures. PMID:27649195

  2. Interconnection of polarization properties and coherence of optical fields.

    Science.gov (United States)

    Zenkova, Claudia Yu

    2014-04-01

    Theoretical and experimental approaches to diagnosing internal spin and orbital optical flows and the corresponding optical forces caused by these flows are offered. These approaches are based on the investigation of the motion of the particles tested in the formed optical field. The dependence of the above-mentioned forces upon the size and optical properties of the particles is demonstrated. The possibility of using kinematic values defining the motion dynamics of particles of the Rayleigh light scattering mechanism to make a quantitative assessment of the degree of coherence of mutually orthogonal waves that are linearly polarized in the incidence plane is demonstrated. The feasibility of using the above mentioned approach, its shortcomings, and its advantages over the interfering method for estimating the degree of coherence are analyzed.

  3. Digital polarization holography advancing 4G optics (Conference Presentation)

    Science.gov (United States)

    De Sio, Luciano; Roberts, David E.; Tabiryan, Nelson V.; Steeves, Diane M.; Kimball, Brian R.

    2016-09-01

    The fourth generation optics (4G optics) enables the realization of novel optical components (lenses, gratings, vector vortices, etc.) by patterning the optical axis orientation in the plane of an anisotropic film. Such components exhibit near 100% diffraction efficiency for wavelengths meeting half-wave retardation condition. In this framework, we have advanced a step-forward by realizing different diffractive waveplates (DWs) with arbitrary spatial patterns of the optical axis orientation by exploiting the capability of a Digital Spatial Light Polarization Converter (DSLPC). The DSLPC is based on a reflective, high resolution Spatial Light Modulator (SLM) combined with an "ad hoc" optical setup. The most attractive feature of the use of a DSLPC for photoalignment is that the orientation of the alignment layer, and therefore of the fabricated liquid crystal (LC) or liquid crystal polymer (LCP) DWs, can be specified on a pixel-by-pixel basis. By varying the optical magnification or de-magnification between the SLM and the alignment layer, the spatial resolution of the photoaligned layer can be adjusted to be optimal for each application. We show that with a simple "click" it is possible to record different high resolution optical components as well as arbitrary patterns ranging from lenses to invisible and even dual labels.

  4. The utility of polarized heliospheric imaging for space weather monitoring.

    Science.gov (United States)

    DeForest, C E; Howard, T A; Webb, D F; Davies, J A

    2016-01-01

    A polarizing heliospheric imager is a critical next generation tool for space weather monitoring and prediction. Heliospheric imagers can track coronal mass ejections (CMEs) as they cross the solar system, using sunlight scattered by electrons in the CME. This tracking has been demonstrated to improve the forecasting of impact probability and arrival time for Earth-directed CMEs. Polarized imaging allows locating CMEs in three dimensions from a single vantage point. Recent advances in heliospheric imaging have demonstrated that a polarized imager is feasible with current component technology.Developing this technology to a high technology readiness level is critical for space weather relevant imaging from either a near-Earth or deep-space mission. In this primarily technical review, we developpreliminary hardware requirements for a space weather polarizing heliospheric imager system and outline possible ways to flight qualify and ultimately deploy the technology operationally on upcoming specific missions. We consider deployment as an instrument on NOAA's Deep Space Climate Observatory follow-on near the Sun-Earth L1 Lagrange point, as a stand-alone constellation of smallsats in low Earth orbit, or as an instrument located at the Sun-Earth L5 Lagrange point. The critical first step is the demonstration of the technology, in either a science or prototype operational mission context.

  5. Performance Monitoring Techniques Supporting Cognitive Optical Networking

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Borkowski, Robert; Zibar, Darko

    2013-01-01

    to solve this issue by realizing a network that can observe, act, learn and optimize its performance, taking into account end-to-end goals. In this letter we present the approach of cognition applied to heterogeneous optical networks developed in the framework of the EU project CHRON: Cognitive...... Heterogeneous Reconfigurable Optical Network. We focus on the approaches developed in the project for optical performance monitoring, which enable the feedback from the physical layer to the cognitive decision system by providing accurate description of the performance of the established lightpaths.......High degree of heterogeneity of future optical networks, such as services with different quality-of-transmission requirements, modulation formats and switching techniques, will pose a challenge for the control and optimization of different parameters. Incorporation of cognitive techniques can help...

  6. Dispersion and polarization dependence of mobile carrier optical nonlinearities

    Science.gov (United States)

    Rustagi, K. C.

    1984-06-01

    Based on the author's earlier work, it is shown that the proper inclusion of carrier scattering should strongly modify the frequency and polarization dependence of optical nonlinearities due to mobile carriers in semiconductors. When the momentum relaxation is much faster than the energy relaxation, the intensity dependent refractive index is enhanced, the induced birefringence becomes a sharp function of the difference frequency ωa-ωb, and a collision induced stimulated Raman effect becomes important.

  7. Simulations and experiments on polarization squeezing in optical fiber

    DEFF Research Database (Denmark)

    Corney, J.F.; Heersink, J.; Dong, R.;

    2008-01-01

    We investigate polarization squeezing of ultrashort pulses in optical fiber, over a wide range of input energies and fiber lengths. Comparisons are made between experimental data and quantum dynamical simulations to find good quantitative agreement. The numerical calculations, performed using both...... effects cause a marked deterioration of squeezing at higher energies and longer fiber lengths. We also calculate the optimum fiber length for maximum squeezing....

  8. Polarization-sensitive optical coherence tomography applied to intervertebral disk

    Science.gov (United States)

    Matcher, Stephen J.; Winlove, Peter; Gangnus, Sergei V.

    2003-07-01

    Polarization-sensitive optical coherence tomography (PSOCT) is a powerful new optical imaging modality that is sensitive to the birefringence properties of tissues. It thus has potential applications in studying the large-scale ordering of collagen fibers within connective tisues and changes related to pathology. As a tissue for study by PSOCT, intervertebral disk respresents an interesting system as the collagen organization is believed to show pronounced variations with depth, on a spatial scale of about 100 μm. We have used a polarization-sensitive optical coherence tomography system to measure the birefringence properties of bovine caudal intervertebral disk and compared this with equine flexor tendon. The result for equine tendon, δ = (3.0 +/- 0.5)x10-3 at 1.3 μm, is in broad agreement with values reported for bovine tendon, while bovine intervertebral disk displays a birefringence of about half this, δ = 1.2 x 10-3 at 1.3 μm. While tendon appears to show a uniform fast-axis over 0.8 mm depth, intervertebral disk shows image contrast at all orientations relative to a linearly polarized input beam, suggesting a variation in fast-axis orientation with depth. These initial results suggest that PSOCT could be a useful tool to study collagen organization within this tissue and its variation with applied load and disease.

  9. Monitoring nanoparticle aggregation by optical procedures

    Science.gov (United States)

    Chicea, Dan

    2013-11-01

    The traditional Dynamic Light Scattering (DLS) produces the average size of the suspended particles from a recorded time series of the light scattered at a particular angle. A modified and simplified version of DLS was designed, tested and used in monitoring FE3O4 nanoparticle aggregation in aqueous suspensions. In addition two another simple and easy to implement optical procedures were tested aiming a qualitative monitoring of the nanoparticle aggregation process. One of them consists of monitoring the time variation of the scattered light intensity at a certain angle and fitting an analytic function on it and the other one in monitoring the refractive index of the aqueous suspension during nanofluid dilution. The results are presented and discussed.

  10. Monitoring Polar Environmental Change Using FORMOSAT-2 Satellite

    Science.gov (United States)

    Huang, C.; Liu, C.; Chang, L.; Wang, S.; Yan, K.; Wu, F.; Wu, A.

    2007-12-01

    Polar ice loss to the sea currently account for virtually all of the sea-level rise that is not attributable to ocean warming. Huge section of the Ayles Ice Shelf broke off into the Arctic Ocean. Permafrost soil is losing its permanence across the Northern Hemisphere, altering ecosystems and damaging roads and buildings across Alaska, Canada, and Russia. Global warming change the polar environment significantly, especially in recent year. The National Space Organization (NSPO) of Taiwan successfully launched FORMOSAT-2 on 20 May 2004. The orbit is designed to be high-altitude,. Sun-synchronous, and daily-revisit. With high agility in attitude control, FORMOSAT-2 can cover the polar areas up to +/- 90 deg latitude. More than 72 Area of interests in Alaska, Canada, Greenland area and Ice land have imaged periodically in 2006 and 2007. The images have 2m resolution in panchromatic band and 8m in multispectral bands, with size of about 24 x 100 km or large. The ability of FORMOSAT-2 daily revisit has been extended to monitor the change of topography for the glacier and ice shelf daily, weekly and monthly. By using the FORMOSAT-2 stereo pair, we can determine the elevation profile (DEM) across the glacier surface. In this paper, we will present the mapping and topography of Greenland glaciers and ice land including Kangerdlugssuaq Glacier, Greenland, Belcher Glacier, Canada and Ayles ice island. We will demonstrate the DEM extract ability from FORMOSAT-2 polar stereo images( up to 82 deg latitude), and compared with the DEM of the popular SRTM, ASTER which can be acquired to 79 deg latitude. It is expected that FORMOSAT-2 polar images will be continuously collected for years and contribute to the research of global environmental change.

  11. Polarized left-handed extraordinary optical transmission of subterahertz waves.

    Science.gov (United States)

    Beruete, Miguel; Sorolla, Mario; Navarro-Cía, Miguel; Campillo, Igor

    2007-06-25

    In this paper we design and measure a metamaterial polarizing device working in the sub-terahertz range. The polarizer is based on a modified version of our previous miniaturized Stacked Hole Array (SHA) structure, an arrangement that combines Extraordinary Optical Transmission (EOT) and Left-Handed Metamaterial (LHM) propagation even under Fresnel illumination. Here, we use a self complementary screen by connecting the holes of an EOT structure. Importantly, EOT remains and simultaneously total reflection is obtained for the orthogonal component. Moreover, by computing the dispersion diagram, we demonstrate that LHM propagation can be achieved for the principal polarization within the stop band of the orthogonal component, which propagates in other bands as a standard forward wave. Finally, we check our conjectures by measuring the transmission and reflection coefficients of screens milled on a low-loss microwave substrate. Measurements have been taken for 1 to 6 stacked wafers and they show clearly that the stack acts as a polarizer with left-handed characteristic. Our results open the way to design of novel polarization control metamaterials at Terahertz wavelengths.

  12. Polarization sensitive spectroscopic optical coherence tomography for multimodal imaging

    Science.gov (United States)

    Strąkowski, Marcin R.; Kraszewski, Maciej; Strąkowska, Paulina; Trojanowski, Michał

    2015-03-01

    Optical coherence tomography (OCT) is a non-invasive method for 3D and cross-sectional imaging of biological and non-biological objects. The OCT measurements are provided in non-contact and absolutely safe way for the tested sample. Nowadays, the OCT is widely applied in medical diagnosis especially in ophthalmology, as well as dermatology, oncology and many more. Despite of great progress in OCT measurements there are still a vast number of issues like tissue recognition or imaging contrast enhancement that have not been solved yet. Here we are going to present the polarization sensitive spectroscopic OCT system (PS-SOCT). The PS-SOCT combines the polarization sensitive analysis with time-frequency analysis. Unlike standard polarization sensitive OCT the PS-SOCT delivers spectral information about measured quantities e.g. tested object birefringence changes over the light spectra. This solution overcomes the limits of polarization sensitive analysis applied in standard PS-OCT. Based on spectral data obtained from PS-SOCT the exact value of birefringence can be calculated even for the objects that provide higher order of retardation. In this contribution the benefits of using the combination of time-frequency and polarization sensitive analysis are being expressed. Moreover, the PS-SOCT system features, as well as OCT measurement examples are presented.

  13. Spectral induced polarization for monitoring electrokinetic remediation processes

    Science.gov (United States)

    Masi, Matteo; Losito, Gabriella

    2015-12-01

    Electrokinetic remediation is an emerging technology for extracting heavy metals from contaminated soils and sediments. This method uses a direct or alternating electric field to induce the transport of contaminants toward the electrodes. The electric field also produces pH variations, sorption/desorption and precipitation/dissolution of species in the porous medium during remediation. Since heavy metal mobility is pH-dependent, the accurate control of pH inside the material is required in order to enhance the removal efficiency. The common approach for monitoring the remediation process both in laboratory and in the field is the chemical analysis of samples collected from discrete locations. The purpose of this study is the evaluation of Spectral Induced Polarization as an alternative method for monitoring geochemical changes in the contaminated mass during remediation. The advantage of this technique applied to field-scale is to offer higher resolution mapping of the remediation site and lower cost compared to the conventional sampling procedure. We carried out laboratory-scale electrokinetic remediation experiments on fine-grained marine sediments contaminated by heavy metal and we made Spectral Induced Polarization measurements before and after each treatment. Measurements were done in the frequency range 10- 3-103 Hz. By the deconvolution of the spectra using the Debye Decomposition method we obtained the mean relaxation time and total chargeability. The main finding of this work is that a linear relationship exists between the local total chargeability and pH, with good agreement. The observed behaviour of chargeability is interpreted as a direct consequence of the alteration of the zeta potential of the sediment particles due to pH changes. Such relationship has a significant value for the interpretation of induced polarization data, allowing the use of this technique for monitoring electrokinetic remediation at field-scale.

  14. Polarization sensitive camera for the in vitro diagnostic and monitoring of dental erosion

    Science.gov (United States)

    Bossen, Anke; Rakhmatullina, Ekaterina; Lussi, Adrian; Meier, Christoph

    Due to a frequent consumption of acidic food and beverages, the prevalence of dental erosion increases worldwide. In an initial erosion stage, the hard dental tissue is softened due to acidic demineralization. As erosion progresses, a gradual tissue wear occurs resulting in thinning of the enamel. Complete loss of the enamel tissue can be observed in severe clinical cases. Therefore, it is essential to provide a diagnosis tool for an accurate detection and monitoring of dental erosion already at early stages. In this manuscript, we present the development of a polarization sensitive imaging camera for the visualization and quantification of dental erosion. The system consists of two CMOS cameras mounted on two sides of a polarizing beamsplitter. A horizontal linearly polarized light source is positioned orthogonal to the camera to ensure an incidence illumination and detection angles of 45°. The specular reflected light from the enamel surface is collected with an objective lens mounted on the beam splitter and divided into horizontal (H) and vertical (V) components on each associate camera. Images of non-eroded and eroded enamel surfaces at different erosion degrees were recorded and assessed with diagnostic software. The software was designed to generate and display two types of images: distribution of the reflection intensity (V) and a polarization ratio (H-V)/(H+V) throughout the analyzed tissue area. The measurements and visualization of these two optical parameters, i.e. specular reflection intensity and the polarization ratio, allowed detection and quantification of enamel erosion at early stages in vitro.

  15. Optical monitoring of the concentration profile of submicron latex particles in flow through a translucent water-permeable tube: demonstration of flow-dependent concentration polarization of plasma proteins at a blood/endothelium boundary

    Science.gov (United States)

    Wada, Shigeo; Iwai, Toshiaki; Karino, Takeshi

    1999-05-01

    It is well accepted that hemodynamics plays an important role in atherogenesis in man. However, the precise mechanisms have not been elucidated yet. Recently, Karino and his coworkers hypothesized that flow-dependent concentration polarization of low-density lipoproteins (LDL: a carrier of cholesterol) may occur at a blood/endothelium boundary, leading to a high risk of atherogenesis in regions of slow flow and low wall shear rate where the concentration of LDL builds up. In this study, we attempted to confirm experimentally their predictions by measuring optically the concentration profile of polystyrene microspheres (used as a model of LDL) flowing in steady flow through a dialyses tube (used as a model of an artery) by transversing a laser beam across the tube and detecting the intensity of the transmitted light. It was found that surface concentration of the microsphere certainly increases with decreasing the flow rate (hence wall shear rate) and it occurs even under the conditions of a very low water filtration velocity encountered in normal arteries in vivo, thus giving a strong support to the hypothesis proposed by Karino et al.

  16. Testglass changer for direct optical monitoring

    Science.gov (United States)

    Zoeller, A.; Hagedorn, H.; Weinrich, W.; Wirth, E.

    2011-09-01

    For the production of high performance multilayer systems with tight specifications and large numbers of layers optical monitoring is essential. Substantial progress was achieved by the introduction of direct monitoring on the rotating substrate holder. Pre production analysis by computer simulation of coating processes helps to optimise monitoring strategies and reduces the effort for expensive and time consuming test runs significantly. However not in any case we can find error compensating monitoring strategies. Also we have to deal with error accumulation effects especially with multi layer systems with large number of layers. Changing the monitor glass after the layer stack is deposited partly is a useful method to discontinue accumulation or to simplify the monitoring strategy. A testglass changer which helps to suppress error accumulation was developed and automized. The testglasses are located on the rotating substrate holder which may be a calotte or a plane substrate holder. It combines the advantages of direct monitoring with the flexibility to change testglasses in a fully automatic process. The basic principle will be described. Results of multilayer systems demonstrate the benefits of the newly developed testglass changer.

  17. Generation of Hidden Optical-Polarization: Squeezing and Non-Classicality

    OpenAIRE

    Gupta, Gyaneshwar K.; Kumar, Akhilesh; Singh, Ravi S

    2010-01-01

    A monochromatic double-mode coherent light endowed with orthogonally polarized photons propagating collinearly is studied in Degenerate Parametric Amplification. Generation of Hidden Optical- Polarized States is shown by non-zero values of Index of Hidden Optical-Polarization. Squeezing in HOPS is demonstrated by recognizing a Squeezing function. The Non-Classical feature of HOPS is observed by 'degree of Hidden Optical-Polarization' which attains non-classical value 'greater than unity'. The...

  18. Polarization-maintaining fiber loop with double optical length and its application to fiber optic gyroscope

    Institute of Scientific and Technical Information of China (English)

    Changsheng Li; Chunxi Zhang; Ningfang Song; Hongjie Xu

    2011-01-01

    @@ A novel polarization maintaining fiber (PMP) loop is proposed and used for an interferometric fiber optic gyroscope (FOG). By splicing a conventional PMF loop with two pigtailed polarization beam splitters, polarized light can be guided to propagate along the slow and fast axes of the PMF in sequence to double its effective optical length in the loop. In particular, the resultant optical length in the combined loop is partially self-compensated for some external disturbances, such as transverse strain. Primary experiments on the FOG using the proposed loop demonstrate that the average static bias deviation between -40 and +60 ℃ is less than 0.050 deg./h, and the average bias variation under conventional random vibration test is less than 0.10 deg./h.%A novel polarization maintaining fiber (PMF) loop is proposed and used for an interferometric fiber optic gyroscope (FOG). By splicing a conventional PMF loop with two pigtailed polarization beam splitters,polarized light can be guided to propagate along the slow and fast axes of the PMF in sequence to double its effective optical length in the loop. In particular, the resultant optical length in the combined loop is partially self-compensated for some external disturbances, such as transverse strain. Primary experiments on the FOG using the proposed loop demonstrate that the average static bias deviation between -40 and +60 ℃ is less than 0.050 deg./h, and the average bias variation under conventional random vibration test is less than 0.10 deg./h.

  19. Optical polarization observations in the Scorpius region: NGC 6124

    CERN Document Server

    Vergne, M Marcela; Martinez, Ruben; Orsatti, Ana Maria; Alvarez, Maria Paula

    2010-01-01

    We have obtained optical multicolour (UBVRI) linear polarimetric data for 46 of the brightest stars in the area of the open cluster NGC 6124 in order to investigate the properties of the interstellar medium (ISM) that lies along the line of sight toward the cluster. Our data yield a mean polarization efficiency of $P_V/E_{B-V}=3.1\\pm$0.62, i.e., a value lower than the polarization produced by the ISM with normal efficiency for an average color excess of $E_{B-V}=0.80$ as that found for NGC 6124. Besides, the polarization shows an orientation of $\\theta \\sim 8^\\circ$.1 which is not parallel to the Galactic Disk,an effect that we think may be caused by the Lupus Cloud. Our analysis also indicates that the observed visual extinction in NGC 6124 is caused by the presence of three different absorption sheets located between the Sun and NGC 6124. The values of the internal dispersion of the polarization ($\\Delta P_V\\sim 1.3% $) and of the colour excess ($\\Delta E_{B-V}\\sim 0.29$ mag) for the members of NGC 6124 see...

  20. RoboPol: First season rotations of optical polarization plane in blazars

    CERN Document Server

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

    2015-01-01

    We present first results on polarization swings in optical emission of blazars obtained by RoboPol, a monitoring program of an unbiased sample of gamma-ray bright blazars specially designed for effective detection of such events. A possible connection of polarization swing events with periods of high activity in gamma rays is investigated using the dataset obtained during the first season of operation. It was found that the brightest gamma-ray flares tend to be located closer in time to rotation events, which may be an indication of two separate mechanisms responsible for the rotations. Blazars with detected rotations have significantly larger amplitude and faster variations of polarization angle in optical than blazars without rotations. Our simulations show that the full set of observed rotations is not a likely outcome (probability $\\le 1.5 \\times 10^{-2}$) of a random walk of the polarization vector simulated by a multicell model. Furthermore, it is highly unlikely ($\\sim 5 \\times 10^{-5}$) that none of o...

  1. Jones matrix analysis for a polarization-sensitive optical coherence tomography system using fiber-optic components

    OpenAIRE

    Park, B. H.; Pierce, M. C.; Cense, B.; De Boer, MR

    2004-01-01

    We present an analysis for polarization-sensitive optical coherence tomography that facilitates the unrestricted use of fiber and fiber-optic components throughout an interferometer and yields sample birefringence, diattenuation, and relative optic axis orientation. We use a novel Jones matrix approach that compares the polarization states of light reflected from the sample surface with those reflected from within a biological sample for pairs of depth scans. The incident polarization alterna...

  2. Imaging caries lesions and lesion progression with polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Fried, Daniel; Xie, John; Shafi, Sahar; Featherstone, John D. B.; Breunig, Thomas; Le, Charles Q.

    2002-06-01

    New diagnostic tools are needed for the characterization of dental caries in the early stages of development. If carious lesions are detected early enough, they can be arrested without the need for surgical intervention. The objective of this study was to demonstrate that polarization sensitive optical coherence tomography (PS-OCT) can be used for the imaging of early caries lesions and for the monitoring of lesion progression over time. High-resolution polarization resolved images were acquired of natural caries lesions and simulated caries lesions of varying severity created over time periods of 1 to 14 days. Linearly polarized light was incident on the tooth samples and the reflected intensity in both orthogonal polarizations was measured. PS-OCT was invaluable for removing the confounding influence of surface reflections and native birefringence and for resolving the surface structure of caries lesions. This study demonstrated that PS-OCT is well suited for the resolution of interproximal and occlusal caries, early root caries, and secondary caries around composite fillings. Longitudinal measurements of lesion progression established a strong correlation (p<0.001) between the reflected light from the lesion area and the square root of time indicating that PS-OCT is well suited for monitoring changes in enamel mineralization over time.

  3. Polarization-dependent losses of integrated optical splitters in glass

    Science.gov (United States)

    Hollenbach, Uwe; Eckstein, Holger; Fabricius, Norbert; Krause, Michael; Kobayashi, Shigeru

    1996-01-01

    During the last two years investments have been made in order to develop new measurement techniques for the characterization of fiber networks. An important characteristic is the neutrality of polarization dependence losses (PDL). Fiber networks contain beside optical sources and detectors a series of basic components like singlemode fibers, integrated optical components (IOC) for the subdistribution, wavelength selective components (WDM) and amplifying elements. The quality of the optical data between transmitters and receivers and the achieved maximum range are determined essentially by the PDL value. In this report the PDL characteristics of passive splitters made by IOT Integrierte Optik GmbH will be described, especially those of N X M splitters. N stands for the entrance port of the splitter and can be 1 or 2. M stands for the exit port of the splitter and can be 2, 4, 8, or 16. Different measuring processes will be described and the achieved measurement results for the PDL will be discussed, In addition to this the different sources of error during the process are described. The achieved results of IOT's N X M splitters have very low PDL values. They are typically smaller than 0.1 dB what makes them excellently suitable for the construction of long-distance optical communication networks. In the meantime such splitters are valued worldwide by different systems suppliers and installed in first optical networks.

  4. Aircraft fiber optic structural health monitoring

    Science.gov (United States)

    Mrad, Nezih

    2012-06-01

    Structural Health Monitoring (SHM) is a sought after concept that is expected to advance military maintenance programs, increase platform operational safety and reduce its life cycle cost. Such concept is further considered to constitute a major building block of any Integrated Health Management (IHM) capability. Since 65% to 80% of military assets' Life Cycle Cost (LCC) is devoted to operations and support (O&S), the aerospace industry and military sectors continue to look for opportunities to exploit SHM systems, capability and tools. Over the past several years, countless SHM concepts and technologies have emerged. Among those, fiber optic based systems were identified of significant potential. This paper introduces the elements of an SHM system and investigates key issues impeding the commercial implementation of fiber optic based SHM capability. In particular, this paper presents an experimental study of short gauge, intrinsic, spectrometric-based in-fiber Bragg grating sensors, for potential use as a component of an SHM system. Fiber optic Bragg grating sensors are evaluated against resistance strain gauges for strain monitoring, sensitivity, accuracy, reliability, and fatigue durability. Strain field disturbance is also investigated by "embedding" the sensors under a photoelastic coating in order to illustrate sensor intrusiveness in an embedded configuration.

  5. Implementing and testing a fiber-optic polarization-based intrusion detection system

    Science.gov (United States)

    Hajj, Rasha El; MacDonald, Gregory; Verma, Pramode; Huck, Robert

    2015-09-01

    We describe a layer-1-based intrusion detection system for fiber-optic-based networks. Layer-1-based intrusion detection represents a significant elevation in security as it prohibits an adversary from obtaining information in the first place (no cryptanalysis is possible). We describe the experimental setup of the intrusion detection system, which is based on monitoring the behavior of certain attributes of light both in unperturbed and perturbed optical fiber links. The system was tested with optical fiber links of various lengths and types, under different environmental conditions, and under changes in fiber geometry similar to what is experienced during tapping activity. Comparison of the results for perturbed and unperturbed links has shown that the state of polarization is more sensitive to intrusion activity than the degree of polarization or power of the received light. The testing was conducted in a simulated telecommunication network environment that included both underground and aerial links. The links were monitored for intrusion activity. Attempts to tap the link were easily detected with no apparent degradation in the visual quality of the real-time surveillance video.

  6. A Magneto-Optical Trap for Polar Molecules

    CERN Document Server

    Stuhl, Benjamin K; Wang, Dajun; Ye, Jun

    2008-01-01

    We propose a method for laser cooling and trapping a substantial class of polar molecules, and in particular titanium (II) oxide (TiO). This method uses pulsed electric fields to nonadiabatically remix the ground-state magnetic sublevels of the molecule, allowing us to build a magneto-optical trap (MOT) based on a quasi-cycling $J'=J"-1$ transition. Monte-Carlo simulations of this electrostatically remixed MOT (ER-MOT) demonstrate the feasibility of cooling TiO to a temperature of 10 $\\mathrm{\\mu}K$ and trapping it with a radiation-pumping-limited lifetime on the order of 80 ms.

  7. Polarized spectral complexes of optical functions of monovalent mercury iodide

    Science.gov (United States)

    Sobolev, V. V.; Sobolev, V. Val.; Anisimov, D. V.

    2015-12-01

    Spectral complexes of optical functions of monovalent mercury iodide Hg2I2 were determined for E ⊥ c and E || c polarizations in the range from 2 to 5.5 eV at 4.2 K. The permittivity and characteristic electron energy loss spectra were expanded in simple components with the determination of their main parameters, including the energy of the maximum and the oscillator strength. The calculations were performed based on known reflectance spectra. Computer programs based on Kramers-Kronig relations and the improved parameter-free method of Argand diagrams were used.

  8. Optical polarization observations in the Scorpius region: NGC 6124

    Science.gov (United States)

    Vergne, M. Marcela; Feinstein, Carlos; Martínez, Ruben; Orsatti, Ana María; Alvarez, María Paula

    2010-04-01

    We have obtained optical multicolour (UBVRI) linear polarimetric data for 46 of the brightest stars in the area of the open cluster NGC 6124 in order to investigate the properties of the interstellar medium (ISM) that lies along the line of sight towards the cluster. Our data yield a mean polarization efficiency of PV/E(B - V) = 3.1 +/- 0.62, i.e. a value lower than the polarization produced by the ISM with normal efficiency for an average colour excess of E(B - V) = 0.80 as that found for NGC 6124. Besides, the polarization shows an orientation of which is not parallel to the Galactic disc, an effect that we think may be caused by the Lupus cloud. Our analysis also indicates that the observed visual extinction in NGC 6124 is caused by the presence of three different absorption sheets located between the Sun and NGC 6124. The values of the internal dispersion of the polarization (ΔPV ~ 1.3 per cent) and of the colour excess (ΔE(B - V) ~ 0.29 mag) for the members of NGC 6124 seem to be compatible with the presence of an intracluster dust component. Only six stars exhibit some evidence of intrinsic polarization. Our work also shows that polarimetry provides an excellent tool to distinguish between member and non-member stars of a cluster. Based on observations obtained at Complejo Astronómico El Leoncito (CASLEO), operated under agreement between the CONICET and the National Universities of La Plata, Córdoba, and San Juan, Argentina. E-mail: cfeinstein@fcaglp.unlp.edu.ar (CF)

  9. Cascaded Optical Buffer Based on Nonlinear Polarization Rotation in Semiconductor Optical Amplifiers

    Institute of Scientific and Technical Information of China (English)

    CHENG Mu; WU Chong-Qing; LIU Hua

    2008-01-01

    A cascaded buffer based on nonlinear polarization rotation in semiconductor optical amplifiers is proposed, which is suitable for fast reconfiguration of buffering time at picoseconds. With the proposed buffer, sixty different buffer times are demonstrated at 2.5 Gb/s.

  10. Optical tractography of the mouse heart using polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Wang, Yuanbo; Yao, Gang

    2013-01-01

    We developed a method to image myocardial fiber architecture in the mouse heart using a Jones matrix-based polarization-sensitive optical coherence tomography (PSOCT) system. The "cross-helical" laminar structure of myocardial fibers can be clearly visualized using this technology. The obtained myocardial fiber organization agrees well with existing knowledge acquired using conventional histology and diffusion tensor magnetic resonance imaging.

  11. Nonlinear optical polarization analysis in chemistry and biology

    CERN Document Server

    Simpson, Garth J

    2017-01-01

    This rigorous yet accessible guide presents a molecular-based description of nonlinear optical polarization analysis of chemical and biological assemblies. It includes discussion of the most common nonlinear optical microscopy and interfacial measurements used for quantitative analysis, specifically second harmonic generation (SHG), two-photon excited fluorescence (2PEF), vibrational sum frequency generation (SFG), and coherent anti-Stokes Raman spectroscopy/stimulated Raman spectroscopy (CARS/SRS). A linear algebra mathematical framework is developed, allowing step-wise systematic connections to be made between the observable measurements and the molecular response. Effects considered include local field corrections, the molecular orientation distribution, rotations between the molecular frame, the local frame and the laboratory frame, and simplifications from molecular and macromolecular symmetry. Specific examples are provided throughout the book, working from the common and relatively simple case studies ...

  12. Fiber Optic Thermal Health Monitoring of Composites

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.; Moore, Jason P.

    2010-01-01

    A recently developed technique is presented for thermographic detection of flaws in composite materials by performing temperature measurements with fiber optic Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of composites with subsurface defects. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared with the calculations using numerical simulation techniques. Methods and limitations for performing in-situ structural health monitoring are discussed.

  13. Polarization mode dispersion in optical fiber transmission systems

    Science.gov (United States)

    Cameron, John Charles

    The birefringence of optical fibers causes pulse broadening in fiber-optic communication systems. This phenomenon is known as polarization mode dispersion (PMD). PMD is one of the most important limiting factors for high capacity fiber-optic systems. A number of aspects of PMD are examined in this thesis. In Chapter 2 an expression is derived for the probability density function of the pulse broadening due to first-order PMD. This result is used to obtain an expression for the system limitation due to PMD. The birefringence of optical fibers is commonly simulated with the waveplate model. In Chapter 3 two standard versions of the waveplate model are introduced. In addition, a novel waveplate model is proposed. The characteristics of the three versions of the waveplate model are examined to confirm their suitability for use in subsequent chapters of the thesis. Simulations with the waveplate model are performed in Chapter 4 for three purposes: (1) to determine the impact of chromatic dispersion on the system limitation due to PMD, (2) to examine the effectiveness of three different PMD compensation techniques in the presence of chromatic dispersion, and (3) to examine the interaction of second-order chromatic dispersion with PMD. The simulations in Chapter 4 reveal that it is possible with one compensation technique to have output pulses that are narrower than the input pulses. In Chapter 5, this anomalous pulse narrowing is demonstrated analytically for a simple model of PMD and through experiment. It is also shown that this pulse narrowing can be explained as an interference phenomenon. Chapter 6 presents measurements of PMD and state of polarization on installed optical fibers. The PMD coefficients of 122 fibers are presented and the results are analyzed in terms of the age of the fibers and the type of cabling. Measurements of the time evolution of PMD and state of polarization are presented for fibers installed in both buried and aerial cables. The uncertainty

  14. Sensitive and accurate dual wavelength UV-VIS polarization detector for optical remote sensing of tropospheric aerosols

    CERN Document Server

    David, G; Thomas, B; Rairoux, P

    2012-01-01

    An UV-VIS polarization Lidar has been designed and specified for aerosols monitoring in the troposphere, showing the ability to precisely address low particle depolarization ratios, in the range of a few percents. Non-spherical particle backscattering coefficients as low as 5 {\\times} 10-8 m-1.sr-1 have been measured and the particle depolarization ratio detection limit is 0.6 %. This achievement is based on a well-designed detector with laser-specified optical components (polarizers, dichroic beamsplitters) summarized in a synthetic detector transfer matrix. Hence, systematic biases are drastically minimized. The detector matrix being diagonal, robust polarization calibration has been achieved under real atmospheric conditions. This UV-VIS polarization detector measures particle depolarization ratios over two orders of magnitude, from 0.6 up to 40 %, which is new, especially in the UV where molecular scattering is strong. Hence, a calibrated UV polarization-resolved time-altitude map is proposed for urban an...

  15. Robopol: Optical polarisation monitoring of blazars

    CERN Document Server

    Angelakis, Emmanouil; Böttcher, Markus; Hovatta, Talvikki; Kiehlmann, Sebastian; Myserlis, Ioannis; Pavlidou, Vassiliki; Zensus, J Anton

    2016-01-01

    The RoboPol program has been monitoring the $R$-band linear polarisation parameters of an unbiased sample of 60 gamma-ray-loud blazars and a "control" sample of 15 gamma-ray-quite ones. The prime drive for the program has been the systematic study of the temporal behaviour of the optical polarisation and particularly the potential association of smooth and long rotations of the polarisation angle with flaring activity at high energies. Here we present the program and discuss a list of selected topics from our studies of the first three observing seasons (2013--2015) both in the angle and in the amplitude domain.

  16. All fiber optics circular-state swept source polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Lin, Hermann; Kao, Meng-Chun; Lai, Chih-Ming; Huang, Jyun-Cin; Kuo, Wen-Chuan

    2014-02-01

    A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ~12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.

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

    Science.gov (United States)

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

    2015-05-29

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

  18. Satellite Monitoring for REDD: Radar vs. Optical

    Science.gov (United States)

    Mitchard, E. T.; Saatchi, S. S.; Ryan, C.; Woollen, E.; Goodman, L. E.; Williams, M.; Gerard, F.; Starkey, M.; Meir, P.

    2010-12-01

    The proposed REDD (Reducing Emissions from Deforestation and Degradation) protocol will only succeed in reducing emissions if deforestation and degradation can be accurately monitored. Ground surveys are prohibitively expensive over large areas, so satellite monitoring will be essential for independently monitoring deforestation and degradation rates, and thus calculating payments. In addition, remote sensing will be needed for developing historical baselines. It is clear that different methodologies will be needed for different project areas, scales and threat types. In addition different methodologies are needed depending on the capabilities of the countries in question: in the context of Africa for example, in-country monitoring tends to be at a basic level, yet for REDD it is important that countries are able to do their own monitoring, so simple methods must be developed and tested. In this paper we present change detection results for different remote sensing methodologies for potential REDD projects in Cameroon and Mozambique. We have shown previously that a good relationship exists between aboveground biomass (AGB) and L-band radar backscatter (Mitchard et al. 2009). The errors in estimation of absolute biomass were still relatively high, in the region of ±25 %. However, it is suspected that some of these errors are intransient, being due to the structure of the landscape and vegetation within a site, and so it has been predicted that errors in change detection are smaller than those for absolute estimation. We present evidence from these sites that this is indeed correct, using ALOS PALSAR L-band radar data from 2007, 2008 and 2009. Optical satellite data is widely used for monitoring deforestation, for example the excellent system run by INPE in Brazil. However, while optical data is good at detecting deforestation occurring progressively in large clear-fell blocks, as in the Amazon, it is less good at detecting small-scale deforestation or degradation

  19. Propagation of partially polarized Gaussian Schell-model beams through aligned and misaligned optical systems

    Institute of Scientific and Technical Information of China (English)

    戈迪; 蔡阳健; 林强

    2005-01-01

    By use of a tensor method, the transform formulae for the beam coherence-polarization matrix of the partially polarized Gaussian Schell-model (GSM) beams through aligned and misaligned optical systems are derived. As an example, the propagation properties of the partially polarized GSM beam passing through a misaligned thin lens are illustrated numerically and discussed in detail. The derived formulae provide a convenient way to study the propagation properties of the partially polarized GSM beams through aligned and misaligned optical systems.

  20. Optical polarization tractography based on polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Yao, Gang; Wang, Yuanbo; Ravanfar, Mohammadreza; Azinfar, Leila; Yao, Xuan; Zhang, Keqing; Duan, Dongsheng

    2016-03-01

    Fibrous tissues exist in many parts of the body, where the directional fiber organization is critical in maintaining their normal functions. Disruption of the normal fibrous structure is often linked to tissue dysfunction. An imaging tool that can reveal the detailed fiber architecture will be valuable for our understanding of the structure-function relationship in these tissues. Here, we described a new high-resolution tractography method developed from Jones matrix polarizationsensitive optical coherence tomography. We demonstrated its applications for visualization of fibrous structures in several different animal tissues.

  1. Passive endoscopic polarization sensitive optical coherence tomography with completely fiber based optical components

    Science.gov (United States)

    Cahill, Lucas; Lee, Anthony M. D.; Pahlevaninezhad, Hamid; Ng, Samson; MacAulay, Calum E.; Poh, Catherine; Lane, Pierre

    2015-03-01

    Polarization Sensitive Optical Coherence Tomography (PSOCT) is a functional extension of Optical Coherence Tomography (OCT) that is sensitive to well-structured, birefringent tissue such as scars, smooth muscle and cartilage. In this work, we present a novel completely fiber based swept source PSOCT system using a fiber-optic rotary pullback catheter. This PSOCT implementation uses only passive optical components and requires no calibration while adding minimal additional cost to a standard structural OCT imaging system. Due to its complete fiber construction, the system can be made compact and robust, while the fiber-optic catheter allows access to most endoscopic imaging sites. The 1.5mm diameter endoscopic probe can capture 100 frames per second at pullback speeds up to 15 mm/s allowing rapid traversal of large imaging fields. We validate the PSOCT system with known birefringent tissues and demonstrate in vivo PSOCT imaging of human oral scar tissue.

  2. Retrieval of aerosol microphysical and optical properties above liquid clouds from POLDER/PARASOL polarization measurements

    Directory of Open Access Journals (Sweden)

    F. Waquet

    2013-04-01

    Full Text Available Most of the current aerosol retrievals from passive sensors are restricted to cloud-free scenes, which strongly reduces our ability to monitor the aerosol properties at a global scale and to estimate their radiative forcing. The presence of aerosol above clouds (AAC affects the polarized light reflected by the cloud layer, as shown by the spaceborne measurements provided by the POlarization and Directionality of Earth Reflectances (POLDER instrument on the PARASOL satellite. In a previous work, a first retrieval method was developed for AAC scenes and evaluated for biomass-burning aerosols transported over stratocumulus clouds. The method was restricted to the use of observations acquired at forward scattering angles (90–120° where polarized measurements are highly sensitive to fine-mode particle scattering. Non-spherical particles in the coarse mode, such as mineral dust particles, do not much polarize light and cannot be handled with this method. In this paper, we present new developments that allow retrieving also the properties of mineral dust particles above clouds. These particles do not much polarize light but strongly reduce the polarized cloud bow generated by the liquid cloud layer beneath and observed for scattering angles around 140°. The spectral attenuation can be used to qualitatively identify the nature of the particles (i.e. accumulation mode versus coarse mode, i.e. mineral dust particles versus biomass-burning aerosols, whereas the magnitude of the attenuation is related to the optical thickness of the aerosol layer. We also use the polarized measurements acquired in the cloud bow to improve the retrieval of both the biomass-burning aerosol properties and the cloud microphysical properties. We provide accurate polarized radiance calculations for AAC scenes and evaluate the contribution of the POLDER polarization measurements for the simultaneous retrieval of the aerosol and cloud properties. We investigate various scenes

  3. OPTICAL POLARIZATION AND SPECTRAL VARIABILITY IN THE M87 JET

    Energy Technology Data Exchange (ETDEWEB)

    Perlman, Eric S.; Cara, Mihai; Bourque, Matthew; Simons, Raymond C. [Department of Physics and Space Sciences, 150 W. University Blvd., Florida Institute of Technology, Melbourne, FL 32901 (United States); Adams, Steven C. [Department of Physics and Astronomy, University of Georgia, Athens, GA 30605 (United States); Harris, D. E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Madrid, Juan P. [Center for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122 (Australia); Clausen-Brown, Eric [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Cheung, C. C. [National Academy of Sciences, Washington, DC 20001 (United States); Stawarz, Lukasz [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Georganopoulos, Markos [Department of Physics, University of Maryland-Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Sparks, William B.; Biretta, John A., E-mail: eperlman@fit.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2011-12-20

    During the last decade, M87's jet has been the site of an extraordinary variability event, with one knot (HST-1) increasing by over a factor 100 in brightness. Variability has also been seen on timescales of months in the nuclear flux. Here we discuss the optical-UV polarization and spectral variability of these components, which show vastly different behavior. HST-1 shows a highly significant correlation between flux and polarization, with P increasing from {approx}20% at minimum to >40% at maximum, while the orientation of its electric vector stayed constant. HST-1's optical-UV spectrum is very hard ({alpha}{sub UV-O} {approx} 0.5, F{sub {nu}}{proportional_to}{nu}{sup -{alpha}}), and displays 'hard lags' during epochs 2004.9-2005.5, including the peak of the flare, with soft lags at later epochs. We interpret the behavior of HST-1 as enhanced particle acceleration in a shock, with cooling from both particle aging and the relaxation of the compression. We set 2{sigma} upper limits of 0.5{delta} pc and 1.02c on the size and advance speed of the flaring region. The slight deviation of the electric vector orientation from the jet position angle (P.A.) makes it likely that on smaller scales the flaring region has either a double or twisted structure. By contrast, the nucleus displays much more rapid variability, with a highly variable electric vector orientation and 'looping' in the (I, P) plane. The nucleus has a much steeper spectrum ({alpha}{sub UV-O} {approx} 1.5) but does not show UV-optical spectral variability. Its behavior can be interpreted as either a helical distortion to a steady jet or a shock propagating through a helical jet.

  4. Optical monitoring system for a turbine engine

    Energy Technology Data Exchange (ETDEWEB)

    Lemieux, Dennis H; Smed, Jan P; Williams, James P; Jonnalagadda, Vinay

    2013-05-14

    The monitoring system for a gas turbine engine including a viewing tube assembly having an inner end and an outer end. The inner end is located adjacent to a hot gas flow path within the gas turbine engine and the outer end is located adjacent to an outer casing of the gas turbine engine. An aperture wall is located at the inner end of the viewing tube assembly and an optical element is located within the viewing tube assembly adjacent to the inner end and is spaced from the aperture wall to define a cooling and purge chamber therebetween. An aperture is defined in the aperture wall for passage of light from the hot gas flow path to the optical element. Swirl passages are defined in the viewing tube assembly between the aperture wall and the optical element for passage of cooling air from a location outside the viewing tube assembly into the chamber, wherein swirl passages effect a swirling movement of air in a circumferential direction within the chamber.

  5. Optical injection induced polarization mode switching and correlation analysis on a VCSEL

    CERN Document Server

    Damodarakurup, Sajeev; Vudayagiri, Ashok

    2015-01-01

    Vertical cavity Surface Emitting Laser (VCSEL) diodes emit light in two polarization modes. The amount of optical feedback is found to influence the intensities of the emitted modes. We investigate the effect of the amount of total output polarization feedback and polarization selective feedback on the intensities of the two emitted polarization modes. A 40 micro seconds resolution time series correlation analysis is done for different feedback conditions and investigate the power spectral continuity and onset of chaos on two polarization modes

  6. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lu Zenghai; Kasaragod, Deepa K; Matcher, Stephen J, E-mail: z.lu@sheffield.ac.uk, E-mail: s.j.matcher@sheffield.ac.uk [Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield, North Campus, Broad Lane, Sheffield, S3 7HQ (United Kingdom)

    2011-02-21

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  7. Landslide Monitoring Based on High-Resolution Distributed Fiber Optic Stress Sensor

    Institute of Scientific and Technical Information of China (English)

    Zhi-Yong Dai; Yong Liu; Li-Xun Zhang; Zhong-Hua Ou; Ce Zhou; Yong-Zhi Liu

    2008-01-01

    A landslide monitoring application is presented by using a high-resolution distributed fiber optic stress sensor. The sensor is used to monitor the intra-stress distribution and variations in landslide bodies, and can be used for the early warning of the occurrence of the landslides. The principle of distributed fiber optic stress sensing and the intra-stress monitoring method for landslides are described in detail. By measuring the distributed polarization mode coupling in the polarization-maintaining fiber, the distributed fiber stress sensor with stress measuring range 0 to 15 Mpa, spatial resolution 10 em and measuring range 0.5 km, is designed. The warning system is also investigated experimentally in the field trial.

  8. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru Miyauchi; Yanjun Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirmlow optical loss and environmental stabilities.

  9. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru; Miyauchi; Yanjun; Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirm low optical loss and environmental stabilities.

  10. Comparison of thermal corneal lesions by optical coherence tomography (OCT) and polarization histology

    Science.gov (United States)

    Koop, Norbert; Brinkmann, Ralf; Kaftan, Bjorn; Asiyo-Vogel, Mary; Engelhardt, Ralf; Birngruber, Reginald

    1996-12-01

    Corneal thermal lesions as typically applied in laser thermokeratoplasty were investigated with optical coherence tomography (OCT) and polarization microscopy. Both methods were used to compare the lesions with respect to the extent and degree of thermal denaturation. The coagulations wee applied on enucleated porcine eyes using a continuously emitting laser diode at a wavelength of 1.86 micrometers . The self developed OCT-system has an axial and lateral resolution of 15-20 micrometers and 26-48 micrometers , respectively, and was used to perform cross sections through the lesions. After OCT on the intact globe, the sections were fixed in formalin and embedded in paraffin. The sections were stained with sirius red and analyzed by polarization light microscopy. The comparison of the backscattered light of the OCT image with the changes in birefringence detected with the polarization microscopy technique found to be in good agreement. Up to four changes in birefringence detected with the polarization microscopy technique found to be in good agreement.Up to four different degrees of denaturation zones could be classified in both methods. OCT findings taken from a noninvasive method and correlated with histological experiences can be used to control the extent and degree of corneal lesions and monitor their healing response.

  11. Development of a portable polarizing stereo monitor using samsung TFT-LCD

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Bum; Park, Soon Yong; Lee, Nam Ho [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-01-01

    Polarizing stereoscopic monitor system uses two polarizing filters to transmit two stereoscopic videos acquired by stereo camera through the separate wave channel of light from monitor to human eyes of the viewer. Polarizing stereoscopic monitor has advantages of image quality, accommodation to human eyes over the other stereoscopic monitors. However, polarizing monitor has disadvantages of weight and size because it uses two CRT displays generally. In this report, we describe the technique of the development of the stereoscopic monitor using high-definition color TFT-LCD displays rather than using CRT displays. We can enhance the mobility and usefulness of the new system by reducing its size and weight remarkably over the conventional CRT monitor system. (author). 27 figs., 4 tabs.

  12. Fibre-Optic Strain Measurement For Structural Integrity Monitoring

    NARCIS (Netherlands)

    Bruinsma, A.J.A.; Zuylen, P. van; Lamberts, C.W.; Krijger, A.J.T. de

    1984-01-01

    A method is demonstrated for monitoring the structural integrity of large structures, using an optical fibre. The strain distribution along the structure is monitored by measuring the attentuation of light along the length of the fibre.

  13. Global aspects of polarization optics and coset space geometry

    Science.gov (United States)

    Arvind; Chaturvedi, S.; Mukunda, N.

    2017-09-01

    We use group theoretic ideas and coset space methods to deal with problems in polarization optics of a global nature. The well-known impossibility of a globally smooth phase convention for electric fields for all points on the Poincaré sphere, and the equally well-known impossibility of real bases for transverse electric vectors for all propagation directions, are expressed in terms of coset spaces SU (2) / U (1), SO (3) / SO (2) respectively. Combining these two negative results in a judicious manner, by making the singularities in coset representatives in the two cases cancel one another, the known possibility of a globally smooth complex basis for transverse electric vectors, and its essential uniqueness, are shown. We find that apart from the groups SU (2) and SO (3) which occur naturally in these problems, the group SU (3) also plays an important role.

  14. Complete all-optical processing polarization-based binary logic gates and optical processors.

    Science.gov (United States)

    Zaghloul, Y A; Zaghloul, A R M

    2006-10-16

    We present a complete all-optical-processing polarization-based binary-logic system, by which any logic gate or processor can be implemented. Following the new polarization-based logic presented in [Opt. Express 14, 7253 (2006)], we develop a new parallel processing technique that allows for the creation of all-optical-processing gates that produce a unique output either logic 1 or 0 only once in a truth table, and those that do not. This representation allows for the implementation of simple unforced OR, AND, XOR, XNOR, inverter, and more importantly NAND and NOR gates that can be used independently to represent any Boolean expression or function. In addition, the concept of a generalized gate is presented which opens the door for reconfigurable optical processors and programmable optical logic gates. Furthermore, the new design is completely compatible with the old one presented in [Opt. Express 14, 7253 (2006)], and with current semiconductor based devices. The gates can be cascaded, where the information is always on the laser beam. The polarization of the beam, and not its intensity, carries the information. The new methodology allows for the creation of multiple-input-multiple-output processors that implement, by itself, any Boolean function, such as specialized or non-specialized microprocessors. Three all-optical architectures are presented: orthoparallel optical logic architecture for all known and unknown binary gates, singlebranch architecture for only XOR and XNOR gates, and the railroad (RR) architecture for polarization optical processors (POP). All the control inputs are applied simultaneously leading to a single time lag which leads to a very-fast and glitch-immune POP. A simple and easy-to-follow step-by-step algorithm is provided for the POP, and design reduction methodologies are briefly discussed. The algorithm lends itself systematically to software programming and computer-assisted design. As examples, designs of all binary gates, multiple

  15. Optical metabolic imaging for monitoring tracheal health

    Science.gov (United States)

    Sharick, Joe T.; Gil, Daniel A.; Choma, Michael A.; Skala, Melissa C.

    2016-04-01

    The health of the tracheal mucosa and submucosa is a vital yet poorly understood component of critical care medicine, and a minimally-invasive method is needed to monitor tracheal health in patients. Of particular interest are the ciliated cells of the tracheal epithelium that move mucus away from the lungs and prevent respiratory infection. Optical metabolic imaging (OMI) allows cellular-level measurement of metabolism, and is a compelling method for assessing tracheal health because ciliary motor proteins require ATP to function. In this pilot study, we apply multiphoton imaging of the fluorescence intensities and lifetimes of metabolic co-enzymes NAD(P)H and FAD to the mucosa and submucosa of ex vivo mouse trachea. We demonstrate the feasibility and potential diagnostic utility of these measurements for assessing tracheal health and pathophysiology at the single-cell level.

  16. Laryngeal imaging with polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Burns, James A.; Kim, Ki Hean; Anderson, R. Rox

    2011-03-01

    Objectives/Hypothesis: Optical coherence tomography (OCT), an imaging technology that provides crosssectional subsurface tissue structure images using backscattered light, is a promising noninvasive, imaging modality for in-vivo assessment of vocal fold layered microstructure. Polarization-sensitive OCT (PS-OCT) augments conventional OCT by detecting changes in the polarization state of reflected light. This study imaged various benign laryngeal pathologies in patients undergoing direct laryngoscopy under general anesthesia to determine whether PS-OCT would provide useful additional information about vocal fold microstructure and glottic surface pathology. Study Design:Prospective clinical trial. Methods: Eighteen patients who were undergoing microlaryngoscopy under general anesthesia for benign glottic disease were imaged bilaterally with OCT and PS-OCT (N=34 vocal folds). Intraoperative microphotography guided placement of the imaging probe. Normalappearing glottic tissue was also imaged if present. When clinically indicated, biopsy or complete removal of the lesion established histologic confirmation. Results: PS-OCT provided high quality, vertical, cross-sectional images up to 1.2mm deep that complemented microlaryngoscopy, and conventional OCT for vocal fold pathologies. Scar tissue was visualized by PS-OCT, characterized by a birefringence pattern more intense than that of normal glottic tissue. Conclusions: Combining PS-OCT with OCT during human vocal cord imaging provides useful information in characterizing vocal cord lesions, particularly scar tissue.

  17. The Polarization Optics for the European Solar Telescope

    Science.gov (United States)

    Bettonvil, F. C. M.; Collados, M.; Feller, A.; Gelly, B. F.; Keller, C. U.; Kentischer, T. J.; López Ariste, A.; Pleier, O.; Snik, F.; Socas-Navarro, H.

    2011-04-01

    EST, the European Solar Telescope, is a 4-m class solar telescope, which will be located at the Canary Islands. It is currently in the conceptual design phase as a European funded project. In order to fulfill the stringent requirements for polarimetric sensitivity and accuracy, the polarimetry has been included in the design work from the very beginning. The overall philosophy has been to use a combination of techniques, which includes a telescope with low (and stable) instrumental polarization, optimal full Stokes polarimeters, differential measurement schemes, fast modulation and demodulation, and accurate calibration, and at the same time not giving up flexibility. The current baseline optical layout consists of a 14-mirror layout, which is polarimetrically compensated and non-varying in time. In the polarization free F2 focus ample space is reserved for calibration and modulators and a polarimetric switch. At instrument level the s-, and p-planes of individual components are aligned, resulting in a system in which eigenvectors can travel undisturbed through the system.

  18. The polarization optics for the European Solar Telescope (EST)

    Science.gov (United States)

    Bettonvil, F. C. M.; Collados, M.; Feller, A.; Gelly, B. F.; Keller, C. U.; Kentischer, T. J.; López Ariste, A.; Pleier, O.; Snik, F.; Socas-Navarro, H.

    2010-07-01

    EST (European Solar Telescope) is a 4-m class solar telescope, which is currently in the conceptual design phase. EST will be located at the Canary Islands and aims at observations with the best possible spectral, spatial and temporal resolution and best polarimetric performance, of the solar photosphere and chromosphere, using a suite of instruments that can efficiently produce two-dimensional spectropolarimetric information of the thermal, dynamic and magnetic properties of the plasma over many scale heights, and ranging from λ=350 until 2300 nm. In order to be able to fulfill the stringent requirements for polarimetric sensitivity and accuracy, from the very beginning the polarimetry has been included in the design work. The overall philosophy has been to use a combination of techniques, which includes a telescope with low (and stable) instrumental polarization, optimal full Stokes polarimeters, differential measurement schemes, fast modulation and demodulation, and accurate calibration. The current baseline optical layout consists of a 14-mirror layout, which is polarimetrically compensated and nonvarying in time. In the polarization free F2 focus ample space is reserved for calibration and modulators and a polarimetric switch. At instrument level the s-, and p-planes of individual components are aligned, resulting in a system in which eigenvectors can travel undisturbed through the system.

  19. Searching for fast optical transients by means of a wide-field monitoring observations with high temporal resolution

    Science.gov (United States)

    Beskin, G.; Karpov, S.; Plokhotnichenko, V.; Bondar, S.; Ivanov, E.; Perkov, A.; Greco, G.; Guarnieri, A.; Bartolini, C.

    We discuss the strategy of search for fast optical transients accompanying gamma-ray bursts by means of continuous monitoring of wide sky fields with high temporal resolution. We describe the design, performance and results of our cameras, FAVOR and TORTORA. Also we discuss the perspectives of this strategy and possible design of next-generation equipment for wide-field monitoring which will be able to detect optical transients and to study their color and polarization properties with high time resolution.

  20. Polarizers, optical bridges and Sagnac interferometers for nanoradian polarization rotation measurements

    CERN Document Server

    Rowe, Alistair; Dilasser, Guillaume; Lassailly, Yves; Peretti, Jacques

    2016-01-01

    The ability to measure nanoradian polarization rotations, $\\theta_F$, in the photon shot noise limit is investigated for partially crossed polarizers (PCP), a static Sagnac interferometer and an optical bridge, each of which can in principal be used in this limit with equivalent figures-of-merit (FOM). In practice a common mode source noise rejection ratio of $1/2\\theta_F$ obtained with the bridge enables this configuration to operate in the photon shot noise limit even at high light intensities. This is demonstrated for a rotation angle of 38 $\\mu$rad, obtained via the Faraday effect in a terbium gallium garnet (TGG), where the experimentally measured FOM in units of $10^{-11}$/photon are 2 (PCP), 1 (Sagnac), and 3.5 (bridge). The superior performance of the bridge is illustrated via the measurement of a 3 nrad rotation occuring when the TGG is placed in an axial magnetic field of 0.9 nT. While the Sagnac is shown to be functionally equivalent to the PCP in terms of the FOM, unlike the PCP it is able to disc...

  1. Planck intermediate results. XXI. Comparison of polarized thermal emission from Galactic dust at 353 GHz with optical interstellar polarization

    CERN Document Server

    Ade, P A R; Alina, D; Aniano, G; Armitage-Caplan, C; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Beichman, C; Benabed, K; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bock, J J; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Burigana, C; Cardoso, J -F; Catalano, A; Chamballu, A; Chary, R -R; Chiang, H C; Christensen, P R; Colombi, S; Colombo, L P L; Combet, C; Couchot, F; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Désert, F -X; Dickinson, C; Diego, J M; Donzelli, S; Doré, O; Douspis, M; Dunkley, J; Dupac, X; Enßlin, T A; Eriksen, H K; Falgarone, E; Fanciullo, L; Finelli, F; Forni, O; Frailis, M; Fraisse, A A; Franceschi, E; Galeotta, S; Ganga, K; Ghosh, T; Giard, M; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gregorio, A; Gruppuso, A; Guillet, V; Hansen, F K; Harrison, D L; Helou, G; Hernández-Monteagudo, C; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Huffenberger, K M; Jaffe, A H; Jaffe, T R; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Kunz, M; Kurki-Suonio, H; Lagache, G; Lähteenmäki, A; Lamarre, J -M; Lasenby, A; Lawrence, C R; Leonardi, R; Levrier, F; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Magalhães, A M; Maino, D; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Mazzotta, P; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Noviello, F; Novikov, D; Novikov, I; Oxborrow, C A; Pagano, L; Pajot, F; Paladini, R; Paoletti, D; Pasian, F; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Pietrobon, D; Plaszczynski, S; Poidevin, F; Pointecouteau, E; Polenta, G; Popa, L; Pratt, G W; Prunet, S; Puget, J -L; Rachen, J P; Reach, W T; Rebolo, R; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rusholme, B; Sandri, M; Savini, G; Scott, D; Spencer, L D; Stolyarov, V; Stompor, R; Sudiwala, R; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Terenzi, L; Toffolatti, L; Tomasi, M; Tristram, M; Tucci, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Vielva, P; Villa, F; Wade, L A; Wandelt, B D; Zonca, A

    2014-01-01

    The Planck survey provides unprecedented full-sky coverage of the submillimetre polarized emission from Galactic dust, bringing new constraints on the properties of dust. The dust grains that emit the radiation seen by Planck in the submillimetre also extinguish and polarize starlight in the optical. Using ancillary catalogues of interstellar polarization and extinction of starlight, we obtain the degree of polarization, $p_V$, and the optical depth in the $V$ band to the star, $\\tau_V$. We extract the submillimetre polarized intensity, $P_S$, and total intensity, $I_S$, measured toward these stars in the Planck 353 GHz channel. We compare the position angle measured in the optical with that measured at 353 GHz, and the column density measure $E(B - V)$ with that inferred from the Planck product map of the submillimetre dust optical depth. For those lines of sight suitable for this comparison, we measure the polarization ratios $R_{S/V} = (P_S/I_S)/(p_V/\\tau_V)$ and $R_{P/p} = P_S / p_V$ through a correlation...

  2. Transient state of polarization in optical ground wire caused by lightning and impulse current

    Science.gov (United States)

    Kurono, Masahiro; Isawa, K.; Kuribara, Masayuki

    1996-08-01

    This paper describes a transient state of polarization in an optical ground wire (OPGW) theoretically, experimentally and with field measurements in lightning conditions, which is considered one of the fastest phenomena of polarization fluctuations in the natural environment. These characteristics will be required for optical coherent communication for utilities in future and for application to sensing of lightning with OPGW.

  3. Optical polarization based logic functions (XOR or XNOR) with nonlinear Gallium nitride nanoslab.

    Science.gov (United States)

    Bovino, F A; Larciprete, M C; Giardina, M; Belardini, A; Centini, M; Sibilia, C; Bertolotti, M; Passaseo, A; Tasco, V

    2009-10-26

    We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. The polarization of the noncollinear generated beam is a function of the polarization of both pump beams, thus we experimentally investigated all possible polarization combinations, evidencing that only some of them are allowed and that the nonlinear interaction of optical signals behaves as a polarization based XOR. The experimental results show the peculiarity of the nonlinear optical response associated with noncollinear excitation, and are explained using the expression for the effective second order optical nonlinearity in noncollinear scheme.

  4. Local control of light polarization with low-temperature fiber optics.

    Science.gov (United States)

    Mack, A H; Riordon, J; Dean, C R; Talbot, R; Gervais, G

    2007-06-01

    A fiber-optic-based polarization control system that uses a backreflection measurement scheme at low temperatures has been developed. This provides a stringent test of the light polarization state at the output of the fiber, allowing for determination and control of the degree of circular polarization; i.e., it can generate linear, right, or left circular polarization with cryogenic fibers. This polarization controller is paving the way toward the control and manipulation of nuclear spins in semiconductors via the optical Overhauser effect and could be used, for example, for the purpose of quantum information processing with the large nuclear spins of GaAs.

  5. Production of polarized negative deuterium ion beam with dual optical pumping in KEK

    Energy Technology Data Exchange (ETDEWEB)

    Kinsho, M.; Ikegami, K.; Takagi, A. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Mori, Y.

    1997-02-01

    To obtain highly nuclear-spin vector polarized negative deuterium ion beam, a dual optically pumped polarized negative deuterium ion source has been developed at KEK. It is possible to select a pure nuclear-spin state with this scheme, and negative deuterium ion beam with 100% nuclear-spin vector polarization can be produced in principle. We have obtained about 70% of nuclear-spin vector polarized negative deuterium ion beam so far. This result may open up a new possibilities for the optically pumped polarized ion source. (author)

  6. Sub-wavelength sized transversely polarized optical needle with exceptionally suppressed side-lobes.

    Science.gov (United States)

    Man, Zhongsheng; Min, Changjun; Du, Luping; Zhang, Yuquan; Zhu, Siwei; Yuan, Xiaocong

    2016-01-25

    It is well known that radially polarized beam could produce an ultra-long longitudinally polarized focus, referred to as "optical needle". In this work, we reveal that the counterpart transversely polarized optical needle (~5.83λ) with exceptionally suppressed sidelobes (9.9% of the maximum of the principal lobe) can be generated by tightly focusing a hybridly polarized beam through a multibelt binary phase filter. A universal analytical model is built up for investigating the depth, uniformity and polarization properties of the needle. We find that there is a trade-off between needle length and intensity uniformity, and the main lobe keeps almost transverse polarization at each observation plane. Such a nondiffraction transversely polarized optical needle has potential applications in ultrahigh density magnetic storage as well as atomic trap and switches.

  7. In vitro birefringence imaging with spectral domain polarization-sensitive optical coherence tomography

    Institute of Scientific and Technical Information of China (English)

    Qiang Gong; Chuanmao Fan; Fan Zhang; Jianquan Yao

    2008-01-01

    Spectral domain polarization-sensitive optical coherence tomography (SDPS-OCT) is a depth-resolved polarization-sensitive interferometry which integrates polarization optics into spectral domain optical co-herence tomography (SD-OCT). This configuration can obtain birefringence information of samples and improve the imaging speed. In this paper, horizontally polarized light is used to replace natural light of the source. Then, right-rotated circularly polarized light is the incident sample light. To obtain two orthogonal components of the polarized interferogram, the reflected light of the reference arm is set to be 45° linearly polarized light. These two components are acquired by two spectrometers synchronously. The system was employed to achieve 12.8-#m axial resolution and 4.36-#m transverse resolution. We have imaged in vitro chicken tendon and muscle tissues with these system.

  8. Great circle solution to polarization-based quantum communication (QC) in optical fiber

    Science.gov (United States)

    Nordholt, Jane Elizabeth; Peterson, Charles Glen; Newell, Raymond Thorson; Hughes, Richard John

    2016-03-15

    Birefringence in optical fibers is compensated by applying polarization modulation at a receiver. Polarization modulation is applied so that a transmitted optical signal has states of polarization (SOPs) that are equally spaced on the Poincare sphere. Fiber birefringence encountered in propagation between a transmitter and a receiver rotates the great circle on the Poincare sphere that represents the polarization bases used for modulation. By adjusting received polarizations, polarization components of the received optical signal can be directed to corresponding detectors for decoding, regardless of the magnitude and orientation of the fiber birefringence. A transmitter can be configured to transmit in conjugate polarization bases whose SOPs can be represented as equidistant points on a great circle so that the received SOPs are mapped to equidistant points on a great circle and routed to corresponding detectors.

  9. Influence of Feedback Levels on Polarized Optical Feedback Characteristics in Zeeman-Birefringence Dual Frequency Lasers

    Institute of Scientific and Technical Information of China (English)

    MAO Wei; ZHANG Shu-Lian; ZHOU Lu-Fei; LIU Xiao-Yan; WANG Ming-Ming

    2007-01-01

    The influence of Feedback levels on the intensity and polarization properties of polarized optical feedback in a Zeeman-birefringence dual frequency laser is systematically investigated. By changing the feedback power ratio, different feedback levels are obtained. Three distinct regimes of polarized optical feedback effects are found and defined as regimes Ⅰ, Ⅱand Ⅲ. The feedback level boundaries among the regimes are acquired experimentally. The theoretical analysis is presented to be in good agreement with the experimental results.

  10. Production of a nuclear spin polarized /sup 23/Na-beam by optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Dreves, W.; Kamke, W.; Broermann, W.; Fick, D.

    1981-11-01

    Nuclear spin polarization of an atomic /sup 23/Na-beam was produced by a combination of optical pumping with a dye laser and a sextupole magnet and alternatively, by optical pumping with two dye lasers. The maximum value measured for the vector polarization was P/sub 2/ = 0.86 +- 0.08, using beam foil spectroscopy. Further improvements of polarized ion sources based on this principle are discussed.

  11. Polarization-Sensitive Interneurons in the Optic Lobe of the Desert Ant Cataglyphis bicolor

    Science.gov (United States)

    Labhart, Thomas

    Desert ants, Cataglyphis bicolor (Hymenoptera), navigate by using compass information provided by skylight polarization. In this study, electrophysiological recordings were made from polarization-sensitive interneurons (POL-neurons) in the optic lobe of Cataglyphis. The POL-neurons exhibit a characteristic polarization opponency. They receive monochromatic input from the UV receptors of the specialized dorsal rim area of the compound eye. Both polarization opponency and monochromacy are features also found in the POL-neurons of crickets (Orthoptera).

  12. Polarization attraction using counter-propagating waves in optical fiber at telecommunication wavelengths.

    Science.gov (United States)

    Pitois, S; Fatome, J; Millot, G

    2008-04-28

    In this work, we report the experimental observation of a polarization attraction process which can occur in optical fibers at telecommunication wavelengths. More precisely, we have numerically and experimentally shown that a polarization attractor, based on the injection of two counter-propagating waves around 1.55microm into a 2-m long high nonlinear fiber, can transform any input polarization state into a unique well-defined output polarization state.

  13. Study of the metastable helium spin polarization in an optically pumped afterglow

    Science.gov (United States)

    Essabaa, S.; Schearer, L. D.; Arianer, J.; Brissaud, I.; Humblot, H.; Zerhouni, O.

    1994-05-01

    A very efficient technique of optical pumping is applied in order to polarize 2 3S 1 metastable 4He atoms within an afterglow by means of a high power LNA laser. An almost complete atom polarization is achieved. This allows the production of an electron beam of appreciable intensity with high polarization well suited to perform a polarized electron source for linear cw accelerators.

  14. Modeling the reverberation of optical polarization in AGN

    Science.gov (United States)

    Rojas Lobos, P. A.; Goosmann, R.; Marin, F.

    2016-12-01

    According to the standard paradigm, the strong and compact luminosity of active galactic nuclei (AGN) is due to multi-temperature black body emission originating from an accretion disk formed around a supermassive black hole. This central engine is thought to be surrounded by a dusty region along the equatorial plane and by ionized winds along the poles. The innermost regions cannot yet be resolved neither in the optical nor in the infrared and it is fair to say that we still lack a satisfactory understanding of the physical processes, geometry and composition of the central (sub-parsec) components of AGN. Like spectral or polarimetric observations, the reverberation data needs to be modeled in order to infer constraints on the AGN geometry (such as the inner radius or the half-opening angle of the dusty torus). In this research note, we present preliminary modeling results using a time-dependent Monte Carlo method to solve the radiative transfer in a simplified AGN set up. We investigate different model configurations using both polarization and time lags and find a high dependency on the geometry to the time-lag response. For all models there is a clear distinction between edge-on or face-on viewing angles for fluxes and time lags, the later showing a higher wavelength-dependence than the former. Time lags, polarization and fluxes point toward a clear dichotomy between the different inclinations of AGN, a method that could help us to determine the true orientation of the nucleus in Seyfert galaxies.

  15. Anisotropic optical response of optically opaque elastomers with conductive fillers as revealed by terahertz polarization spectroscopy

    Science.gov (United States)

    Okano, Makoto; Watanabe, Shinichi

    2016-12-01

    Elastomers are one of the most important materials in modern society because of the inherent viscoelastic properties due to their cross-linked polymer chains. Their vibration-absorbing and adhesive properties are especially useful and thus utilized in various applications, for example, tires in automobiles and bicycles, seismic dampers in buildings, and seals in a space shuttle. Thus, the nondestructive inspection of their internal states such as the internal deformation is essential in safety. Generally, industrial elastomers include various kinds of additives, such as carbon blacks for reinforcing them. The additives make most of them opaque in a wide spectral range from visible to mid-infrared, resulting in that the nondestructive inspection of the internal deformation is quite difficult. Here, we demonstrate transmission terahertz polarization spectroscopy as a powerful technique for investigating the internal optical anisotropy in optically opaque elastomers with conductive additives, which are transparent only in the terahertz frequency region. The internal deformation can be probed through the polarization changes inside the material due to the anisotropic dielectric response of the conductive additives. Our study about the polarization-dependent terahertz response of elastomers with conductive additives provides novel knowledge for in situ, nondestructive evaluation of their internal deformation.

  16. Coherent optical control of polarization with a critical metasurface

    CERN Document Server

    Kang, Ming

    2015-01-01

    We describe the mechanism by which a metamaterial surface can act as an ideal phase-controlled rotatable linear polarizer. With equal-power linearly polarized beams incident on each side of the surface, varying the relative phase rotates the polarization angles of the output beams, while keeping the polarization exactly linear. The explanation is based on coupled-mode theory and the idea of coherent perfect absorption into auxiliary polarization channels. The polarization-rotating behavior occurs at a critical point of the coupled-mode theory, which can be associated with the exceptional point of a parity-time (PT) symmetric effective Hamiltonian.

  17. Photodynamic therapy monitoring with optical coherence angiography

    Science.gov (United States)

    Sirotkina, M. A.; Matveev, L. A.; Shirmanova, M. V.; Zaitsev, V. Y.; Buyanova, N. L.; Elagin, V. V.; Gelikonov, G. V.; Kuznetsov, S. S.; Kiseleva, E. B.; Moiseev, A. A.; Gamayunov, S. V.; Zagaynova, E. V.; Feldchtein, F. I.; Vitkin, A.; Gladkova, N. D.

    2017-01-01

    Photodynamic therapy (PDT) is a promising modern approach for cancer therapy with low normal tissue toxicity. This study was focused on a vascular-targeting Chlorine E6 mediated PDT. A new angiographic imaging approach known as M-mode-like optical coherence angiography (MML-OCA) was able to sensitively detect PDT-induced microvascular alterations in the mouse ear tumour model CT26. Histological analysis showed that the main mechanisms of vascular PDT was thrombosis of blood vessels and hemorrhage, which agrees with angiographic imaging by MML-OCA. Relationship between MML-OCA-detected early microvascular damage post PDT (within 24 hours) and tumour regression/regrowth was confirmed by histology. The advantages of MML-OCA such as direct image acquisition, fast processing, robust and affordable system opto-electronics, and label-free high contrast 3D visualization of the microvasculature suggest attractive possibilities of this method in practical clinical monitoring of cancer therapies with microvascular involvement. PMID:28148963

  18. Study of optical properties and proteoglycan content of tendons by polarization sensitive optical coherence tomography

    Science.gov (United States)

    Yang, Ying; Rupani, Asha; Bagnaninchi, Pierre; Wimpenny, Ian; Weightman, Alan

    2012-08-01

    The highly orientated collagen fibers in tendons play a critical role for transferring tensile stress, and they demonstrate birefringent optical properties. However, the influence that proteoglycans (PGs) have on the optical properties of tendons is yet to be fully elucidated. PGs are the essential components of the tendon extracellular matrix; the changes in their quantities and compositions have been associated with tendinopathies. In this study, polarization sensitive optical coherence tomography (PS-OCT) has been used to reveal the relationship between PG content/location and birefringence properties of tendons. Fresh chicken tendons were imaged at regular intervals by PS-OCT and polarization light microscopy during the extraction of PGs, using guanidine hydrochloride (GuHCl). Complementary time-lapsed images taken from the two modalities mutually demonstrated that the extraction of PGs disturbed the local organization of collagen bundles. This corresponded with a decrease in birefringence and associated banding pattern observed by PS-OCT. Furthermore, this study revealed there was a higher concentration of PGs in the outer sheath region than in the fascicles, and therefore the change in birefringence was reduced when extraction was performed on unsheathed tendons. The results provide new insights of tendon structure and the role of PGs on the structural stability of tendons, which also demonstrates the great potential for using PS-OCT as a diagnostic tool to examine tendon pathology.

  19. Mathematical Description of Acousto-Optic Tunable Filter Orthogonal Polarizing Method

    Institute of Scientific and Technical Information of China (English)

    XU Kexin; WEN Huizhi; ZHANG Hao; FAN Guofang; YANG Jisheng

    2005-01-01

    The transfer function of the optical splitting system of the acousto-optic tunable filter (AOTF) is deduced to be a reference to optical design. The characteristic matrix (transfer function) of AOTF is used to describe quantitatively the characters of polarization elements in the orthogonal polarizing system. According to the characteristic matrix, the included angle of polarizer's transmission direction and polarization analyzer's transmission direction should be 90°. As a result the signal to noise ratio increased about 20 times though the light intensity was reduced to 54.3% polarization analyzer are 0.74, which is an intrinsic character. The orthogonal polarizing method is an effective method to get rid of the influence of zero order light and improve the spectrum resolution and signal-to-noise ratio.

  20. Study of fast control of optical polarization; Henko jotai no kosoku seigyo hoshiki no kento

    Energy Technology Data Exchange (ETDEWEB)

    Kurono, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1996-03-01

    To develop a control method of SOP (state of optical polarization) for coping with the polarization fluctuation velocity of OPGW (optical ground wire), fast control techniques of optical polarization was investigated using electro-optic devices. Based on the results, polarization control equipment was designed. Birefringence in the applied electric field is utilized for the polarization control using electro-optic devices. High electric field region with long configuration by the electric fields intersecting at right angles to the optical pass is effective for enhancing the voltage sensitivity. A z-propagation bulk-type LN (LiNbO3; lithium niobate) crystal was employed, to examine size and voltage which can ensure the phase shift angle required for the polarization control. As a result, the size of 40 mm length and 1 mm thickness and the voltage of about 500 V at the wavelength of 1.55 {mu}m were obtained, which was feasible to be installed. A structure of the element with four electrodes on each face was proposed. When the applied voltage was controlled, the principal axis angle of birefringence was a half of the electric field rotating angle, and the phase shift angle was in proportion to the strength of electric field. It was theoretically clarified that the simultaneous controls of the both can be performed. Thus, the fast polarization control coping with the polarization fluctuation velocity of OPGW was revaluated. 30 refs., 7 figs., 4 tabs.

  1. Jones matrix analysis for a polarization-sensitive optical coherence tomography system using fiber-optic components

    Science.gov (United States)

    Hyle Park, B.; Pierce, Mark C.; Cense, Barry; de Boer, Johannes F.

    2004-11-01

    We present an analysis for polarization-sensitive optical coherence tomography that facilitates the unrestricted use of fiber and fiber-optic components throughout an interferometer and yields sample birefringence, diattenuation, and relative optic axis orientation. We use a novel Jones matrix approach that compares the polarization states of light reflected from the sample surface with those reflected from within a biological sample for pairs of depth scans. The incident polarization alternated between two states that are perpendicular in a Poincaré sphere representation to ensure proper detection of tissue birefringence regardless of optical fiber contributions. The method was validated by comparing the calculated diattenuation of a polarizing sheet, chicken tendon, and muscle with that obtained by independent measurement. The relative importance of diattenuation versus birefringence to angular displacement of Stokes vectors on a Poincaré sphere was quantified.

  2. Optical Pumping of Metastable Helium Atoms in Polarized Electron Sources

    Science.gov (United States)

    Brissaud, I.

    1995-04-01

    In this paper we present a comparison between the Orsay and Rice University polarized electron sources. Different explanations of the polarization degradation are discussed for the two cases. For the Rice source radiation, trapping can account for the observed reduction in polarization because of the high absorption cross sections associated with the D1 transition. Some improvements are proposed that might increase the electron polarization.

  3. Optical Pumping of Metastable Helium Atoms in Polarized Electron Sources

    OpenAIRE

    1995-01-01

    In this paper we present a comparison between the Orsay and Rice University polarized electron sources. Different explanations of the polarization degradation are discussed for the two cases. For the Rice source radiation, trapping can account for the observed reduction in polarization because of the high absorption cross sections associated with the D1 transition. Some improvements are proposed that might increase the electron polarization.

  4. Secured optical fiber communication using polarization restoration technique and channel characterization

    Science.gov (United States)

    Punekar, Nikhil; Darunkar, Bhagyashri; Verma, Pramode

    2016-02-01

    Optical fiber channels are used as media to transfer the information globally. This paper presents an implementation of a novel procedure using which a secured communication between two parties can be carried out using polarized beam of light over an optical fiber. The paper presents the experimental results obtained of the procedure in the lab environment and a security analysis of the same. It is observed that polarization state of a light pulse cannot be retained as it travels over an optical fiber because of the birefringence phenomenon. Multiple environmental factors such as pressure, vibration, temperature, etc. also add a non-linearity to the birefringence of an optical fiber leading towards an unpredictable polarization state changes over the course of an optical fiber. The proposed procedure helps the receiving party to successfully retrieve the data in the form of a polarization state transmitted by the sending party without having any knowledge about the state of polarization at the transmitting end. The paper also explains an added layer of security the procedure provides to the communicating parties to make it difficult for an adversary to fetch the data being transferred. The proposed system does not depend on the wavelength of the light being used, nor does it depend upon the type of the optical fiber used for the communication. Using this procedure, multiple bits of secured information can be sent over an optical fiber in a single polarized pulse and retrieved at the receiving end, also known as Polarization Shift Keying.

  5. Quantum reconstruction of an intense polarization squeezed optical state

    DEFF Research Database (Denmark)

    Marquardt, Ch.; Heersink, J.; Dong, R.

    2007-01-01

    We perform a reconstruction of the polarization sector of the density matrix of an intense polarization squeezed beam starting from a complete set of Stokes measurements. By using an appropriate quasidistribution, we map this onto the Poincare space, providing a full quantum mechanical...... characterization of the measured polarization state....

  6. Experimental generation of tripartite polarization entangled states of bright optical beams

    Science.gov (United States)

    Wu, Liang; Yan, Zhihui; Liu, Yanhong; Deng, Ruijie; Jia, Xiaojun; Xie, Changde; Peng, Kunchi

    2016-04-01

    The multipartite polarization entangled states of bright optical beams directly associating with the spin states of atomic ensembles are one of the essential resources in the future quantum information networks, which can be conveniently utilized to transfer and convert quantum states across a network composed of many atomic nodes. In this letter, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The tripartite entangled states of light at the frequency resonant with D1 line of Rubidium atoms are transformed into the continuous variable polarization entanglement among three bright optical beams via an optical beam splitter network. The obtained entanglement is confirmed by the extended criterion for polarization entanglement of multipartite quantized optical modes.

  7. Human psychophysiological activity monitoring methods using fiber optic sensors

    Science.gov (United States)

    Zyczkowski, M.; Uzieblo-Zyczkowska, B.

    2010-10-01

    The paper presents the concept of fiber optic sensor system for human psycho-physical activity detection. A fiber optic sensor that utilizes optical phase interferometry or intensity in modalmetric to monitor a patient's vital signs such as respiration cardiac activity, blood pressure and body's physical movements. The sensor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acusto-mechanical signals from the patient are coupled into the optical fiber. The system can be implemented in embodiments ranging form a low cost in-home to a high end product for in hospital use.

  8. Optical fiber sensors and their application in monitoring stress build-up in dental resin cements

    Science.gov (United States)

    Ottevaere, H.; Tabak, M.; Fernandez Fernandez, A.; Berghmans, F.; Thienpont, H.

    2005-09-01

    The field of optical fiber sensing is highly diverse and this diversity is perceived as a great advantage over more conventional sensors in that an optical sensor can be tailored to measure any of a myriad of physical parameters. In this paper we present a niche application for optical fiber sensors in the domain of biophotonics, namely the monitoring of stress build-up during the curing process of dental resin cements. We discuss the origin of this stress build-up and the problems it can cause when treating patients. Optical fiber sensors aim at excelling in two kind of applications: firstly to perform quality control on batch produced dental cements and measure their total material shrinkage, secondly to monitor the hardening of the cement during in-vivo measurements resulting in the dynamic measurement of the shrinkage and to control the stress in a facing based restoration. We therefore investigated two types of optical fiber sensors as alternatives to conventional measurement techniques; namely polarimetric optical fiber sensors and fiber Bragg gratings written in polarization maintaining fibers. After discussing the results obtained with both optical fiber sensors, we will conclude with a critical assessment of the suitability of the two proposed sensing configurations for multi-parameter stress monitoring.

  9. Effects of polarization and absorption on laser induced optical breakdown threshold for skin rejuvenation

    Science.gov (United States)

    Varghese, Babu; Bonito, Valentina; Turco, Simona; Verhagen, Rieko

    2016-03-01

    Laser induced optical breakdown (LIOB) is a non-linear absorption process leading to plasma formation at locations where the threshold irradiance for breakdown is surpassed. In this paper we experimentally demonstrate the influence of polarization and absorption on laser induced breakdown threshold in transparent, absorbing and scattering phantoms made from water suspensions of polystyrene microspheres. We demonstrate that radially polarized light yields a lower irradiance threshold for creating optical breakdown compared to linearly polarized light. We also demonstrate that the thermal initiation pathway used for generating seed electrons results in a lower irradiance threshold compared to multiphoton initiation pathway used for optical breakdown.

  10. Optical polarizer/isolator based on a rectangular waveguide with helical grooves

    CERN Document Server

    Shvets, G

    2006-01-01

    A chirality-based approach to making a one-way waveguide that can be used as an optical isolator or a polarizer is described. The waveguide is rectangular, and chirality is introduced by making slanted rectangular grooves on the waveguide walls. Chirality of the waveguide manifests as a strong circular dichroism, and is responsible for transmitting one circular polarization of light and reflecting the other. Optical isolation of the propagating circular polarization is accomplished when the chiral waveguide is placed in front of a non-chiral optical device. Even the crudest implementations of chirality are shown to exhibit significant circular dichroism.

  11. An Index (PC) Aimed at Monitoring the (P)olar (C)ap for Magnetic Activity

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — PC is an index for magnetic activity in the (P)olar (C)ap. It is based on data from a single nearpole station, and aimed to monitor the polar cap magnetic activity...

  12. Simultaneous and independent optical impairments monitoring using singular spectrum analysis of asynchronously sampled signal amplitudes

    Science.gov (United States)

    Guesmi, Latifa; Menif, Mourad

    2015-09-01

    Optical performance monitoring (OPM) becomes an inviting topic in high speed optical communication networks. In this paper, a novel technique of OPM based on a new elaborated computation approach of singular spectrum analysis (SSA) for time series prediction is presented. Indeed, various optical impairments among chromatic dispersion (CD), polarization mode dispersion (PMD) and amplified spontaneous emission (ASE) noise are a major factors limiting quality of transmission data in the systems with data rates lager than 40 Gbit/s. This technique proposed an independent and simultaneous multi-impairments monitoring, where we used SSA of time series analysis and forecasting. It has proven their usefulness in the temporal analysis of short and noisy time series in several fields, that it is based on the singular value decomposition (SVD). Also, advanced optical modulation formats (100 Gbit/s non-return-to zero dual-polarization quadrature phase shift keying (NRZ-DP-QPSK) and 160 Gbit/s DP-16 quadrature amplitude modulation (DP-16QAM)) offering high spectral efficiencies have been successfully employed by analyzing their asynchronously sampled amplitude. The simulated results proved that our method is efficient on CD, first-order PMD, Q-factor and OSNR monitoring, which enabled large monitoring ranges, the CD in the range of 170-1700 ps/nm.Km and 170-1110 ps/nm.Km for 100 Gbit/s NRZ-DP-QPSK and 160 Gbit/s DP-16QAM respectively, and also the DGD up to 20 ps is monitored. We could accurately monitor the OSNR in the range of 10-40 dB with monitoring error remains less than 1 dB in the presence of large accumulated CD.

  13. Carious growth monitoring with optical coherence tomography

    Science.gov (United States)

    Freitas, A. Z.; Zezell, D. M.; Mayer, M. P. A.; Ribeiro, A. C.; Gomes, A. S. L.; Vieira, N. D., Jr.

    2006-02-01

    Optical Coherence Tomography was used to monitor subsurface caries evolution process in vitro. Human tooth was used and bacteria were employed to induce caries lesions. Twenty-five human third molars, were used in this study. The teeth were cut longitudinally at mesio-distal direction; the surfaces were coated with nail varnish except for two squared windows (2x4 mm); at the cement-enamel junction. Artificial lesions were induced by a S. Mutans microbiological culture. The samples (N = 50) were divided into groups according to the demineralization time: 3, 5, 7, 9 and 11 days. The culture medium, was changed each 48 hours. After the demineralization process the samples were rinsed with double-deionized water and stored in a humid environment. The OCT system was implemented with average power of 96 μW in the sample arm, providing a 23 μm of axial resolution. The images were produced with lateral scans step of 10 μm. The detection system was composed by a detector, a demodulator and a computer. With the images generated by OCT it was possible to determine the lesion depth as function of sample exposition time to microbiological culture. We observed that the depth of the lesion in the root dentine increased from 70 μm to 230 μm, depending of exposure time, and follows the bacterial population growth law. This OCT system accurately depicts hard dental tissue and it was able to detect early caries in its structure, providing a powerful contactless high resolution image of lesions.

  14. Absolute Measurement Fiber-optic Sensors in Large Structural Monitoring

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The security of civil engineering is an important task due to the economic, social and environmental significance. Compared with conventional sensors, the optical fiber sensors have their unique characteristics.Being durable, stable and insensitive to external perturbations,they are particular interesting for the long-term monitoring of civil structures.Focus is on absolute measurement optical fiber sensors, which are emerging from the monitoring large structural, including SOFO system, F-P optical fiber sensors, and fiber Bragg grating sensors. The principle, characteristic and application of these three kinds of optical fiber sensors are described together with their future prospects.

  15. Dual-polarization interferometric fiber-optic gyroscope with an ultra-simple configuration.

    Science.gov (United States)

    Wang, Zinan; Yang, Yi; Lu, Ping; Luo, Rongya; Li, Yulin; Zhao, Dayu; Peng, Chao; Li, Zhengbin

    2014-04-15

    We demonstrate a novel dual-polarization interferometric fiber-optic gyroscope (IFOG), which needs only one coupler and no polarizer. Polarization nonreciprocity (PN) errors in common IFOGs will increase significantly if the polarizer is absent, or if only one coupler is used. In our setup, however, PN errors are effectively compensated by using two balanced polarizations. The 2 km coil, open-loop configuration obtains a bias instability of 0.02°/h in detecting the Earth's rotation rate. Its performance difference from the conventional two-coupler IFOG is only a stable bias, caused by coupler nonreciprocity.

  16. Doubling transmission capacity in optical wireless system by antenna horizontal- and vertical-polarization multiplexing.

    Science.gov (United States)

    Li, Xinying; Yu, Jianjun; Zhang, Junwen; Dong, Ze; Chi, Nan

    2013-06-15

    We experimentally demonstrate 2×56 Gb/s two-channel polarization-division-multiplexing quadrature-phase-shift-keying signal delivery over 80 km single-mode fiber-28 and 2 m Q-band (33-50 GHz) wireless link, adopting antenna horizontal- (H-) and vertical-polarization (V-polarization) multiplexing. At the wireless receiver, classic constant-modulus-algorithm equalization based on digital signal processing can realize polarization demultiplexing and remove the crosstalk at the same antenna polarization. By adopting antenna polarization multiplexing, the signal baud rate and performance requirements for optical and wireless devices can be reduced but at the cost of double antennas and devices, while wireless transmission capacity can also be increased but at the cost of stricter requirements for V-polarization. The isolation is only about 19 dB when V-polarization deviation approaches 10°, which will affect high-speed (>50 Gb/s) wireless delivery.

  17. Fast, high-precision optical polarization synthesizer for ultracold-atom experiments

    CERN Document Server

    Robens, Carsten; Alt, Wolfgang; Meschede, Dieter; Zopes, Jonathan; Alberti, Andrea

    2016-01-01

    We propose a novel approach to precisely synthesize arbitrary polarization states of light with a high modulation bandwidth. Our approach consists in superposing two laser light fields with the same wavelength, but with opposite circular polarizations, where the phase and amplitude of each light field are individually controlled. To assess the precision of the synthesized polarization states, we characterize static spatial variations of the polarization over the wavefront, as well as the noise spectral density of temporal fluctuations. We find that static polarization distortions limit the extinction ratio to $2\\times 10^{-5}$, corresponding to a 0.01% reduction of the degree of polarization (DOP). We also obtain that temporal fluctuations give rise to a $0.2^\\circ$ uncertainty in the state of polarization (SOP). We recently demonstrated an application of the polarization synthesizer (Robens et al., arXiv:1608.02410) to create two fully independent, controllable optical lattices, which trap atoms depending on...

  18. Thickness dependent enhancement of the polar magneto-optic Kerr effect in Co magnetoplasmonic nanostructures

    CERN Document Server

    Melander, Emil; Caballero, Blanca; García-Martín, Antonio; Hjörvarsson, Björgvin; Kapaklis, Vassilios; Papaioannou, Evangelos Th

    2016-01-01

    We reveal the influence of the thickness of the ferromagnetic layer on the surface plasmon polariton assisted enhancement of the polar magneto-optic Kerr effect. The optical and magneto-optical response is strongly altered by the thickness of the magnetic layer as shown in specular reflectivity and polar magneto-optical Kerr effect measurements. That the main spectral feature of the magneto-optical enhancement does not only depend on the in-plane structuring of the sample but also on the out-of-plane geometrical parameters, such as the thickness. For the specific thickness of 100 nm for the Co layer an sixfold enhancement of the polar magneto-optical effect is observed, as compared to a continuous Co film of the same thickness.

  19. X-ray and optical observations of four polars

    Science.gov (United States)

    Worpel, H.; Schwope, A. D.; Granzer, T.; Reinsch, K.; Schwarz, R.; Traulsen, I.

    2016-08-01

    Aims: We investigate the temporal and spectral behaviour of four polar cataclysmic variables from the infrared to X-ray regimes, refine our knowledge of the physical parameters of these systems at different accretion rates, and search for a possible excess of soft X-ray photons. Methods: We obtained and analysed four XMM-Newton X-ray observations of three of the sources, two of them discovered with the SDSS and one in the RASS. The X-ray data were complemented by optical photometric and spectroscopic observations and, for two sources, archival Swift observations. Results: SDSSJ032855.00+052254.2 was X-ray bright in two XMM-Newton and two Swift observations, and shows transitions from high and low accretion states on a timescale of a few months. The source shows no significant soft excess. We measured the magnetic field strength at the main accreting pole to be 39 MG and the inclination to be 45° ≤ i ≤ 77°, and we refined the long-term ephemeris. SDSSJ133309.20+143706.9 was X-ray faint. We measured a faint phase X-ray flux and plasma temperature for this source, which seems to spend almost all of its time accreting at a low level. Its inclination is less than about 76°. 1RXSJ173006.4+033813 was X-ray bright in the XMM-Newton observation. Its spectrum contained a modest soft blackbody component, not luminous enough to be considered a significant soft excess. We inferred a magnetic field strength at the main accreting pole of 20 to 25 MG, and that the inclination is less than 77° and probably less than 63°. V808 Aur, also known as CSS081231:J071126+440405, was X-ray faint in the Swift observation, but there is nonetheless strong evidence for bright and faint phases in X-rays and perhaps in UV. Residual X-ray flux from the faint phase is difficult to explain by thermal emission from the white dwarf surface, or by accretion onto the second pole. We present a revised distance estimate of 250 pc. Conclusions: The three systems we were able to study in detail

  20. Overview of non-intercepting beam-size monitoring with optical diffraction radiation

    CERN Document Server

    Lumpkin, Alex H

    2012-01-01

    The initial demonstrations over the last several years of the use of optical diffraction radiation (ODR) as non-intercepting electron-beam-parameter monitors are reviewed. Developments in both far-field imaging and near-field imaging are addressed for ODR generated by a metal plane with a slit aperture, a single metal plane, and two-plane interferences. Polarization effects and sensitivities to beam size, divergence, and position will be discussed as well as a proposed path towards monitoring 10-micron beam sizes at 25 GeV.

  1. Overview of nonintercepting beam-size monitoring with optical diffraction radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, Alex H.; /Fermilab

    2010-08-01

    The initial demonstrations over the last several years of the use of optical diffraction radiation (ODR) as nonintercepting electron-beam-parameter monitors are reviewed. Developments in both far-field imaging and near-field imaging are addressed for ODR generated by a metal plane with a slit aperture, a single metal plane, and two-plane interferences. Polarization effects and sensitivities to beam size, divergence, and position will be discussed as well as a proposed path towards monitoring 10-micron beam sizes at 25 GeV.

  2. Early dental caries detection using a fibre-optic coupled polarization-resolved Raman spectroscopic system.

    Science.gov (United States)

    Ko, Alex C-T; Hewko, Mark; Sowa, Michael G; Dong, Cecilia C S; Cleghorn, Blaine; Choo-Smith, Lin-P'ing

    2008-04-28

    A new fibre-optic coupled polarization-resolved Raman spectroscopic system was developed for simultaneous collection of orthogonally polarized Raman spectra in a single measurement. An application of detecting incipient dental caries based on changes observed in Raman polarization anisotropy was also demonstrated using the developed fibre-optic Raman spectroscopic system. The predicted reduction of polarization anisotropy in the Raman spectra of caries lesions was observed and the results were consistent with those reported previously with Raman microspectroscopy. The capability of simultaneous collection of parallel- and cross-polarized Raman spectra of tooth enamel in a single measurement and the improved laser excitation delivery through fibre-optics demonstrated in this new design illustrates its future clinical potential.

  3. Magneto-optic Crystal Polarization Controller Assisted Mode-Locked Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guang-Zhen; GUI Li-Li; XIAO Xiao-Sheng; YANG Chang-Xi

    2011-01-01

    We report a passively mode-locked erbium-doped fiber laser based on a compact magneto-optic crystal polarization controller. The length of the polarization controller consisting of four magneto-optic crystal rotators and two quarter wave-plates is only 10cm.Adjusting the polarization controller, central wavelength around 1559nm and repetition rate 21.10 MHz mode-locked pulse are obtained. Pulse duration and 3 dB spectrum width are 598.4fs and 6.24nm respectively. Single pulse energy is about 151.7pJ. Because of its small size, low insertion loss,good controllability and negligible dispersion, the magneto-optic crystal polarization controller could be an ideal polarization controller in fiber lasers.

  4. Coherent optical control of polarization with a critical metasurface

    Science.gov (United States)

    Kang, Ming; Chong, Y. D.

    2015-10-01

    We present a mechanism by which a metamaterial surface, or metasurface, can act as an ideal phase-controlled rotatable linear polarizer. Using coupled-mode theory and the idea of coherent perfect absorption into auxiliary polarization channels, we show how the losses and near-field couplings on the metasurface can be balanced so that, with equal-power linearly polarized beams incident on each side, varying the relative phase rotates the polarization angles of the output beams while maintaining zero ellipticity. The system can be described by a non-Hermitian effective Hamiltonian which is parity-time (P T ) symmetric, although there is no actual gain present; perfect polarization conversion occurs at the eigenfrequencies of this Hamiltonian, and the polarization rotating behavior occurs at the critical point of its P T -breaking transition.

  5. Enhanced Transmission Stability of Polarization Solitons in Birefringent Fibres with an Optical Phase Conjugator

    Institute of Scientific and Technical Information of China (English)

    陈伟成; 谢嘉宁; 路洪; 徐文成

    2003-01-01

    An optical phase conjugator is used to enhance transmission stability of polarization solitons in highly birefringent fibres. Two polarization solitons form a breather in fibres with low birefringence firstly and the optical phase conjugator is used to make the spectra of polarization solitons converse, which results in the fact that the polarization soliton along the fast axis is compressed due to the strengthened self-phase modulation effect. Two polarization solitons are compressed further due to the cross-phase modulation effect. The enhanced nonlinear effects make the central peak frequencies of two polarization solitons shift to the larger range in opposite directions so that they trap each other fully to suppress the effect of birefringence.

  6. High Performance Fiber-Optic Sensor for Environmental Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Los Gatos Research (LGR) proposes to develop a low-cost, compact, lightweight, rugged and easy-to-use environmental monitoring optical fiber sensor device based on...

  7. Accurate Gain Flattening Filters Manufactured by Optical Compensation Monitoring Method

    Institute of Scientific and Technical Information of China (English)

    J. J. Pan; FengQing Zhou; James Guo; Mingjie Zhang; Ming Zhou; Joy Jiang

    2003-01-01

    GFFs with less than 0.4 dB peak-to-peak error functions are routinely fabricated using commercially available coating machines by utilizing the natural error compensation mechanism of wavelength variable turning point optical monitoring method.

  8. Improvement of a polarized alkali ion source by means of optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Dreves, W.; Koch, E.; Jaensch, H.; Kamke, W.; Broermann, W.; Fick, D.

    1982-01-01

    A source for polarized alkali ions can be improved considerably by optical pumping of the atom beam in combination with a modified weak field transition. M-level populations were investigated using laser induced fluorescence in a magnetic field.

  9. Polarization contrast in reflection near-field optical microscopy with uncoated fibre tips

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.; Langbein, Wolfgang; Hvam, Jørn Märcher

    1999-01-01

    Using cross-hatched, patterned semiconductor surfaces and round 20-nm-thick gold pads on semiconductor wafers, we investigate the imaging characteristics of a reflection near-field optical microscope with an uncoated fibre tip for different polarization configurations and light wavelengths....... Is is shown that cross-polarized detection allows one to effectively suppress far-field components in the detected signal and to realise imaging of optical contrast on the sub-wavelength scale. The sensitivity window of our microscope, i.e. the scale on which near-field optical images represent mainly optical...

  10. LIMITS ON OPTICAL POLARIZATION DURING THE PROMPT PHASE OF GRB 140430A

    Energy Technology Data Exchange (ETDEWEB)

    Kopac, D.; Mundell, C. G.; Arnold, D. M.; Steele, I. A.; Kobayashi, S.; Lamb, G. P.; Smith, R. J.; Virgili, F. J. [Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool, L3 5RF (United Kingdom); Japelj, J.; Gomboc, A. [Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Guidorzi, C.; Dichiara, S. [Department of Physics and Earth Sciences, University of Ferrara, via Saragat 1, I-44122, Ferrara (Italy); Harrison, R. M. [Department of Astrophysics, School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Melandri, A. [INAF—Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Castro-Tirado, A. J.; Gorosabel, J.; Sánchez-Ramírez, R.; Oates, S. R. [Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomia s/n, E-18008 Granada (Spain); Järvinen, A. [AIP—Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Jelínek, M., E-mail: drejc.kopac@fmf.uni-lj.si [ASU-CAS—Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 251 65 Ondřejov (Czech Republic)

    2015-11-01

    Gamma-ray burst GRB 140430A was detected by the Swift satellite and observed promptly with the imaging polarimeter RINGO3 mounted on the Liverpool Telescope, with observations beginning while the prompt γ-ray emission was still ongoing. In this paper, we present densely sampled (10-s temporal resolution) early optical light curves (LCs) in 3 optical bands and limits to the degree of optical polarization. We compare optical, X-ray, and gamma-ray properties and present an analysis of the optical emission during a period of high-energy flaring. The complex optical LC cannot be explained merely with a combination of forward and reverse shock emission from a standard external shock, implying additional contribution of emission from internal shock dissipation. We estimate an upper limit for time averaged optical polarization during the prompt phase to be as low as P < 12% (1σ). This suggests that the optical flares and early afterglow emission in this GRB are not highly polarized. Alternatively, time averaging could mask the presence of otherwise polarized components of distinct origin at different polarization position angles.

  11. LONG-TERM OPTICAL POLARIZATION VARIABILITY OF THE TeV BLAZAR 1ES 1959+650

    Energy Technology Data Exchange (ETDEWEB)

    Sorcia, Marco; Benitez, Erika; Cabrera, Jose I. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apdo. 70-264, Mexico D.F. 04510 (Mexico); Hiriart, David; Lopez, Jose M. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apdo. 810, Ensenada, B.C. 22800 (Mexico); Mujica, Raul [Instituto Nacional de Astrofisica, Optica y Electronica, Apdo. Postal 51 y 216, 72000 Tonantzintla, Puebla (Mexico); Heidt, Jochen; Mommert, Michael [ZAH, Landessternwarte Heidelberg, Koenigstuhl, D-69117 Heidelberg (Germany); Agudo, Ivan [Instituto Nacional de Astrofisica de Andalucia, CSIC, Apartado 3004, E-18080 Granada (Spain); Nilsson, Kari, E-mail: msorcia@astro.unam.mx [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaeisaelaentie 20, FI-21500 Piikkioe (Finland)

    2013-06-01

    A detailed analysis of the optical polarimetric variability of the TeV blazar 1ES 1959+650 from 2007 October 18 to 2011 May 5 is presented. The source showed maximum and minimum brightness states in the R band of 14.08 {+-} 0.03 mag and 15.20 {+-} 0.03 mag, respectively, with a maximum variation of 1.12 mag, and a maximum polarization degree of P = (12.2 {+-} 0.7)%, with a maximum variation of 10.7%. From 2009 August to November, a correlation between the optical R-band flux and the degree of linear polarization was found with a correlation coefficient r {sub pol} = 0.984 {+-} 0.025. The source presented a preferential position angle of optical polarization of {approx}153 Degree-Sign , with variations of 10 Degree-Sign -50 Degree-Sign , which is in agreement with the projected position angle of the parsec-scale jet found at 43 GHz. From the Stokes parameters we infer the existence of two optically thin synchrotron components that contribute to the polarized flux. One of them is stable with a constant polarization degree of 4%. Assuming a stationary shock for the variable component, we estimated some parameters associated with the physics of the relativistic jet: the magnetic field, B {approx} 0.06 G, the Doppler factor, {delta}{sub 0} {approx} 23, the viewing angle, {Phi} {approx} 2. Degree-Sign 4, and the size of the emission region r{sub b} {approx} 5.6 Multiplication-Sign 10{sup 17} cm. Our study is consistent with the spine-sheath model of explaining the polarimetric variability displayed by this source during our monitoring.

  12. Long-term Optical Polarization Variability of the TeV Blazar 1ES 1959+650

    Science.gov (United States)

    Sorcia, Marco; Benítez, Erika; Hiriart, David; López, José M.; Cabrera, José I.; Mújica, Raúl; Heidt, Jochen; Agudo, Iván; Nilsson, Kari; Mommert, Michael

    2013-06-01

    A detailed analysis of the optical polarimetric variability of the TeV blazar 1ES 1959+650 from 2007 October 18 to 2011 May 5 is presented. The source showed maximum and minimum brightness states in the R band of 14.08 ± 0.03 mag and 15.20 ± 0.03 mag, respectively, with a maximum variation of 1.12 mag, and a maximum polarization degree of P = (12.2 ± 0.7)%, with a maximum variation of 10.7%. From 2009 August to November, a correlation between the optical R-band flux and the degree of linear polarization was found with a correlation coefficient r pol = 0.984 ± 0.025. The source presented a preferential position angle of optical polarization of ~153°, with variations of 10°-50°, which is in agreement with the projected position angle of the parsec-scale jet found at 43 GHz. From the Stokes parameters we infer the existence of two optically thin synchrotron components that contribute to the polarized flux. One of them is stable with a constant polarization degree of 4%. Assuming a stationary shock for the variable component, we estimated some parameters associated with the physics of the relativistic jet: the magnetic field, B ~ 0.06 G, the Doppler factor, δ0 ~ 23, the viewing angle, Φ ~ 2.°4, and the size of the emission region rb ~ 5.6 × 1017 cm. Our study is consistent with the spine-sheath model of explaining the polarimetric variability displayed by this source during our monitoring.

  13. Optical monitoring for power law fluids during spin coating.

    Science.gov (United States)

    Jardim, P L G; Michels, A F; Horowitz, F

    2012-01-30

    Optical monitoring is applied, in situ and in real time, to non-newtonian, power law fluids in the spin coating process. An analytical exact solution is presented for thickness evolution that well fits to most measurement data. As result, typical rheological parameters are obtained for several CMC (carboximetilcelullose) concentrations and rotation speeds. Optical monitoring thus precisely indicates applicability of the model to power law fluids under spin coating.

  14. Implementation of an optical S-R flip-flop with polarization encoded light signal

    Institute of Scientific and Technical Information of China (English)

    Debajyoti; Samanta; Sourangshu; Mukhopadhyay

    2009-01-01

    A new method is proposed to implement an optical S-R flip-flop by polarization encoded light signal,necessary optical nonlinear material and half-wave plate.In this system the real time speed of operation can be achieved,and at the time of transmission the average power of a byte remains constant.This polarization encoded flip-flop can act as a memory cell.

  15. Cross-polarized wave generation by effective cubic nonlinear optical interaction.

    Science.gov (United States)

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

    2001-03-15

    A new cubic nonlinear optical effect in which a linearly polarized wave propagating in a single quadratic medium is converted into a wave that is cross polarized to the input wave is observed in BBO crystal. The effect is explained by cascading of two different second-order processes: second-harmonic generation and difference frequency mixing.

  16. On polarization metrology (estimation) of the degree of coherence of optical waves

    DEFF Research Database (Denmark)

    Angelsky, O.V.; Hanson, Steen Grüner; Zenkova, C. Yu

    2009-01-01

    A new approach is proposed for estimating the degree of coherence of optical waves. The possibility of transformation of the spatial polarization distribution in the measured spatial intensity distribution for determining the degree of correlation of superposing waves, linearly polarized in the p...

  17. Invited Article: Polarization diversity and modulation for high-speed optical communications: architectures and capacity

    Directory of Open Access Journals (Sweden)

    William Shieh

    2016-07-01

    Full Text Available Polarization is one of the fundamental properties of optical waves. To cope with the exponential growth of the Internet traffic, optical communications has advanced by leaps and bounds within the last decade. For the first time, the polarization domain has been extensively explored for high-speed optical communications. In this paper, we discuss the general principle of polarization modulation in both Jones and Stokes spaces. We show that there is no linear optical device capable of transforming an arbitrary input polarization into one that is orthogonal to itself. This excludes the receiver self-polarization diversity architecture by splitting the signal into two branches, and then transferring one of the branches into orthogonal polarization. We next propose a novel Stokes vector (SV detection architecture using four single-ended photodiodes (PD that can recover a full set of SV. We then derive a closed-form expression for the information capacity of different SV detection architectures and compare the capacity of our proposed architectures with that of intensity-modulated directly-detected (IM/DD method. We next study the 3-PD SV detection architecture where a subset of SV is detected, and devise a novel modulation algorithm that can achieve 2-dimensional modulation with the 3-PD detection. By using cost-effective SV receivers, polarization modulation and multiplexing offers a powerful solution for short-reach optical networks where the wavelength domain is quickly exhausted.

  18. Invited Article: Polarization diversity and modulation for high-speed optical communications: architectures and capacity

    Science.gov (United States)

    Shieh, William; Khodakarami, Hamid; Che, Di

    2016-07-01

    Polarization is one of the fundamental properties of optical waves. To cope with the exponential growth of the Internet traffic, optical communications has advanced by leaps and bounds within the last decade. For the first time, the polarization domain has been extensively explored for high-speed optical communications. In this paper, we discuss the general principle of polarization modulation in both Jones and Stokes spaces. We show that there is no linear optical device capable of transforming an arbitrary input polarization into one that is orthogonal to itself. This excludes the receiver self-polarization diversity architecture by splitting the signal into two branches, and then transferring one of the branches into orthogonal polarization. We next propose a novel Stokes vector (SV) detection architecture using four single-ended photodiodes (PD) that can recover a full set of SV. We then derive a closed-form expression for the information capacity of different SV detection architectures and compare the capacity of our proposed architectures with that of intensity-modulated directly-detected (IM/DD) method. We next study the 3-PD SV detection architecture where a subset of SV is detected, and devise a novel modulation algorithm that can achieve 2-dimensional modulation with the 3-PD detection. By using cost-effective SV receivers, polarization modulation and multiplexing offers a powerful solution for short-reach optical networks where the wavelength domain is quickly exhausted.

  19. Correction technology of a polarization lidar with a complex optical system.

    Science.gov (United States)

    Di, Huige; Hua, Hangbo; Cui, Yan; Hua, Dengxin; Li, Bo; Song, Yuehui

    2016-08-01

    A complex optical system used in polarization lidars often modifies the input polarization of the return signal so that it may significantly impact depolarization estimates and introduce errors to polarization lidar measurements. In most cases, retardation, depolarization, and misalignment of the system exist at the same time and interact with each other. Polarization effects of the system cannot be represented by a simple correction coefficient, so they cannot be removed using a traditional calibration method. Detailed analysis and correction technologies were provided to remove systematic biases in estimating depolarization values from a polarization lidar owing to multiple optical components. The Mueller matrices from an emitter to a receiver were calculated, and the expression for an aerosol depolarization parameter including system polarization effects was derived and obtained. In addition, the correction algorithm based on the Mueller matrix was introduced and provided. A polarization lidar was established, and the polarization characteristics of its optical components were measured with a laboratory ellipsometer; then, the Mueller matrix of the receiver was calculated and obtained. Lidar observations were performed, and our correction algorithm was applied to lidar field data. The results show that the correction method can significantly remove systematic polarization effects.

  20. Optical polarizing neutron devices designed for pulsed neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, M.; Kurahashi, K.; Endoh, Y. [Tohoku Univ, Sendai (Japan); Itoh, S. [National Lab. for High Energy Physics, Tsukuba (Japan)

    1997-09-01

    We have designed two polarizing neutron devices for pulsed cold neutrons. The devices have been tested at the pulsed neutron source at the Booster Synchrotron Utilization Facility of the National Laboratory for High Energy Physics. These two devices proved to have a practical use for experiments to investigate condensed matter physics using pulsed cold polarized neutrons.

  1. Monitoring the stress build-up in dental cements: a novel optical characterization technique

    Science.gov (United States)

    Ottevaere, Heidi; Tabak, M.; Bartholomees, F.; de Wilde, Willy P.; Veretennicoff, Irina P.; Thienpont, Hugo

    2001-01-01

    It is well known that during the curing of dental cements, polymerization shrinkage induces unacceptable stresses, which can result into cracks and an over-sensitivity of the teeth. We demonstrate that polarimetric optical fiber sensors can be used to characterize this shrinkage quantitatively. To determine the time evolution and the amount of shrinkage we embed a highly birefringent optical fiber in the dental cement and analyze the change in optical polarization at its output. This change is a measure for the dynamic stress-build up. We also demonstrate the repeatability of our characterization method for these cements. Moreover we given indications that this technique allows for in- vivo monitoring of the stress build-up dynamics between dentine and porcelain facings. This may bring durable all-ceramic restorations closer to reality. In this paper we present the principle of this original optical fiber sensor, its practical implementation and the experimental results we obtained for this application.

  2. Corrosion induced strain monitoring through fibre optic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Grattan, S K T [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Belfast, BT9 5AG (United Kingdom); Basheer, P A M [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Belfast, BT9 5AG (United Kingdom); Taylor, S E [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Belfast, BT9 5AG (United Kingdom); Zhao, W [School of Engineering and Mathematical Sciences, City University, Northampton Square, London, EC1V 0HB (United Kingdom); Sun, T [School of Engineering and Mathematical Sciences, City University, Northampton Square, London, EC1V 0HB (United Kingdom); Grattan, K T V [School of Engineering and Mathematical Sciences, City University, Northampton Square, London, EC1V 0HB (United Kingdom)

    2007-10-15

    The use of strain sensors is commonplace within civil engineering. Fibre optic strain sensors offer a number of advantages over the current electrical resistance type gauges. In this paper the use of fibre optic strain sensors and electrical resistance gauges to monitor the production of corrosion by-products has been investigated and reported.

  3. Fiber Optics Deliver Real-Time Structural Monitoring

    Science.gov (United States)

    2013-01-01

    To alter the shape of aircraft wings during flight, researchers at Dryden Flight Research Center worked on a fiber optic sensor system with Austin-based 4DSP LLC. The company has since commercialized a new fiber optic system for monitoring applications in health and medicine, oil and gas, and transportation, increasing company revenues by 60 percent.

  4. Thermo-optical and polarized light studies of MWCNT doped PDLCs

    Science.gov (United States)

    Mahajan, Jyoti; Gupta, Sureshchandra J.; Saxena, S.; Swati, K.

    2016-05-01

    Optical properties of liquid crystals (LCs) are very essential in an understanding of the technological applications of the LCs. Polymer Dispersed Liquid Crystals (PDLCs) are prepared by dispersing the liquid crystal droplets in polymer matrix. Experiments to study thermo-optical properties and polarized light studies are considered in the present work. PDLCs used in the present work are composed of poly (methyl methacrylate) and cholestric liquid crystal namely cholesteryl propionate. These are further doped with Multi-walled carbon Nanotubes (MWCNTs). Thermo-optical study reveals that there is decrease in the nematic-isotropic phase transition temperature (Clearing point temperature i.e. CPT) with increase in the concentration of MWCNTs. The effect of polarized light is studied by means of change in polarization which is characteristic of the material properties. The optical constants graphs obtained from ellipsometry provides the possibility of the use of composite material for optical switching systems.

  5. Optical polarization of C13 nuclei in diamond through nitrogen vacancy centers

    Science.gov (United States)

    King, Jonathan P.; Coles, Patrick J.; Reimer, Jeffrey A.

    2010-02-01

    We determine the polarization of the bulk C13 nuclear-spin system in diamond produced by interaction with optically oriented nitrogen vacancy (NV) defect centers. C13 nuclei are polarized into the higher-energy Zeeman state with a bulk-average polarization up to 5.2%, although local polarization may be higher. The kinetics of polarization are temperature independent and occur within 5 min. Fluctuations in the dipolar field of the NV-center spin bath are identified as the mechanism by which nuclear-spin transitions are induced near defect centers. Polarization is then transported to the bulk material via spin diffusion, which accounts for the observed kinetics of polarization. These results indicate control over the nuclear-spin bath, a methodology to study dynamics of an NV-center ensemble, and application to sensitivity-enhanced NMR.

  6. Analysis of CMOS Compatible Cu-Based TM-Pass Optical Polarizer

    KAUST Repository

    Ng, Tien Khee

    2012-02-10

    A transverse-magnetic-pass (TM-pass) optical polarizer based on Cu complementary metal-oxide-semiconductor technology platform is proposed and analyzed using the 2-D method-of-lines numerical model. In designing the optimum configuration for the polarizer, it was found that the metal-insulator-metal (MIM) polarizer structure is superior compared to the insulator-metal-insulator polarizer structure due to its higher polarization extinction ratio (PER) and low insertion loss. An optimized MIM TM-pass polarizer exhibits simulated long wavelength pass filter characteristics of > ?1.2 ?m, with fundamental TM 0 and TE 0 mode transmissivity of >70% and <5%, respectively, and with PER ?11.5 dB in the wavelength range of 1.2-1.6 ?m. The subwavelength and submicrometer features of this TM-polarizer are potentially suitable for compact and low power photonics integrated circuit implementation on silicon-based substrates. © 1989-2012 IEEE.

  7. Optical Monitoring of OT 546 in 2009

    Indian Academy of Sciences (India)

    Difu Guo; Shaoming Hu; Xu Chen

    2014-09-01

    We reported the monitoring results of OT 546 in V, R and I bands, observed on 22 nights from February 16 to July 1 in 2009 at Weihai Observatory, Shandong university. During our monitoring, its variability amplitude was small and a possible microvariability was detected on one night using both C and F tests.

  8. Optically Polarized Conduction-Band Electrons in Tungsten Observed by Spin-Polarized Photoemission

    DEFF Research Database (Denmark)

    Zürcher, P.; Meier, F.; Christensen, N. E.

    1979-01-01

    Along the (100) direction of tungsten, interband transitions induced by circularly polarized light of energy 1.5 eV......Along the (100) direction of tungsten, interband transitions induced by circularly polarized light of energy 1.5 eV...

  9. Optically controlled polarization in highly oriented ferroelectric thin films

    Science.gov (United States)

    Borkar, Hitesh; Tomar, M.; Gupta, Vinay; Katiyar, Ram S.; Scott, J. F.; Kumar, Ashok

    2017-08-01

    The out-of-plane and in-plane polarization of (Pb0.6Li0.2Bi0.2)(Zr0.2Ti0.8)O3 (PLBZT) thin film has been studied in the dark and under illumination from a weak light source of a comparable bandgap. A highly oriented PLBZT thin film was grown on a LaNiO3/LaAlO3 substrate by pulsed laser deposition; it showed well-saturated polarization which was significantly enhanced under light illumination. We employed two configurations for polarization characterization: the first deals with out-of-plane polarization with a single capacitor under investigation, whereas the second uses two capacitors connected in series via the bottom electrode. Two different configurations were illuminated using different energy sources and their effects were studied. The latter configuration shows a significant change in polarization under light illumination that may provide an extra degree of freedom for device miniaturization. The polarization was also tested using positive-up and negative-down measurements, confirming robust polarization and its switching under illumination.

  10. Proposal for a simple integrated optical ion-exchange waveguide polarizer with a liquid crystal overlay

    Science.gov (United States)

    Wang, Pengfei; Semenova, Yuliya; Zheng, Jie; Wu, Qiang; Hatta, Agus Muhamad; Farrell, Gerald

    2011-02-01

    A simple, compact electro-optic polarizer based on an ion-exchanged glass channel waveguide covered with a nematic liquid crystal (LC) is proposed. A full-vectorial beam propagation method is employed to simulate this device for the first time. For the cases of zero and strong LC surface anchoring, the performance of the proposed polarizer under different applied voltages is analyzed numerically. Analysis indicates that surface anchoring of the liquid crystal is a key issue influencing the performance for the proposed optical polarizer device.

  11. Control of polarization signal distortion by frequency domain phase conjugation in optical fiber systems

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Optical frequency domain phase conjugation(FDPC) is based on phase conjuga-tion of spectrum of an input signal.It is equivalent to the phase conjugation and the time reversal of the temporal envelope of an input signal.The use of FDPC to con-trol polarization signal distortion in birefringent optical fiber systems is proposed.Evolution of polarization signals in the system using midway FDPC is analyzed theoretically and simulated numerically.It is shown that the distortion of polariza-tion signals can be controlled effectively by FDPC.The impairments due to disper-sion and nonlinear effects can be suppressed simultaneously.

  12. Control of polarization signal distortion by frequency domain phase conjusation in optical fiber systems

    Institute of Scientific and Technical Information of China (English)

    BU Yang; WANG XiangZhao

    2008-01-01

    Optical frequency domain phase conjugation (FDPC) is based on phase conjugation of spectrum of an input signal. It is equivalent to the phase conjugation and the time reversal of the temporal envelope of an input signal. The use of FDPC to con-trol polarization signal distortion in birefringent optical fiber systems is proposed. Evolution of polarization signals in the system using midway FDPC is analyzed theoretically and simulated numerically. It is shown that the distortion of polariza-tion signals can be controlled effectively by FDPC. The impairments due to disper-sion and nonlinear effects can be suppressed simultaneously.

  13. Hazard monitoring in mines using fibre optic sensors

    Science.gov (United States)

    Liu, T.; Wang, C.; Wei, Y.; Zhao, Y.; Huo, D.; Shang, Y.; Wang, Z.; Ning, Y.

    2009-10-01

    We report the development of a comprehensive safety monitoring solution for coal mines. A number of fibre optic sensors have been developed and deployed for safety monitoring of mine roof integrity and hazardous gases. The FOS-based mine hazard detection system offers unique advantages of intrinsic safety, multi-location and multi-parameter monitoring. They can be potentially used to build expert systems for mine hazard early detection and prevention.

  14. Optical and near-infrared linear polarization of low and intermediate-gravity ultracool dwarfs

    Science.gov (United States)

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

    2017-04-01

    We aim to study the optical and near-infrared linear polarimetric properties of a sample of young M7-L7 dwarfs (≈ 1-500 Myr) with spectroscopic signatures of low- and intermediate-gravity atmospheres. We collected optical (RIZ) and near-infrared (YJHKs) linear polarimetry images on various time-scales from ∼0.2 h to months. Linear polarization degrees in the interval 0-1.5 per cent (I and J bands) were measured with accuracies ranging from ±0.1 to ±0.9 per cent depending on the observing filter and the target brightness. We found that the young field dwarfs in our sample show similar polarimetric degrees at both I and J bands, and that there is no obvious trend with the spectral type. The two Taurus sources in our sample show intense levels of J-band linear polarization probably due to surrounding discs. By compiling data from the literature for high-gravity M7-L7 dwarfs with likely ages ≥500 Myr, we did not observe any apparent difference in the linear polarimetry intensity between the young and old samples that could be ascribed to differing atmospheric gravities. Polarimetric variability with peak to peak amplitudes up to 1.5 per cent is detected on scales of about a rotation in two out of four targets that were monitored over several hours. Long-term polarimetric variability is also detected in nearly all dwarfs of the sample with data spanning months to years.

  15. Metamaterial optical diodes for linearly and circularly polarized light

    CERN Document Server

    Plum, E; Zheludev, N I

    2010-01-01

    The total intensity of light transmitted at non-normal incidence thorough planar metamaterials can be different for forward and backward propagation. For metamaterial patterns of different symmetries we observe this effect for circularly or linearly polarized light.

  16. Polarization modeling for the main optics of Chinese Giant Solar Telescope

    Science.gov (United States)

    Yuan, Shu; Fu, Yu; Jin, Zhenyu

    2016-07-01

    Chinese Giant Solar Telescope, which has a 8m diameter segmented primary mirror, is a plan for the next generation ground-based large solar telescope in China. A major scientific requirement for this telescope is the high accuracy polarimetry. In this paper, the instrumental polarization of the main optics is analyzed by polarization modeling, which is caused by off-axial field of view, spider asymmetry, nonuniform segment gap and segment coating. The result shows that the net polarization is sensitive to the asymmetrical spider leg widening and the uniformity of the segment optical property. For meeting the accuracy requirement, the extinction ratio and retardence error for each segment should be less than 0.3% and 0.8 degree, respectively. Generally, the ring segmented primary mirror have advantage in controlling the instrumental polarization for large main optics.

  17. Systematic Study of Gamma-ray bright Blazars with Optical Polarization and Gamma-ray Variability

    CERN Document Server

    Itoh, Ryosuke; Fukazawa, Yasushi; Uemura, Makoto; Tanaka, Yasuyuki T; Kawabata, Koji S; Madejski, Grzegorz M; Schinzel, Frank K; Kanda, Yuka; Shiki, Kensei; Akitaya, Hiroshi; Kawabata, Miho; Moritani, Yuki; Nakaoka, Tatsuya; Ohsugi, Takashi; Sasada, Mahito; Takaki, Katsutoshi; Takata, Koji; Ui, Takahiro; Yamanaka, Masayuki; Yoshida, Michitoshi

    2016-01-01

    Blazars are highly variable active galactic nuclei which emit radiation at all wavelengths from radio to gamma-rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies and it also varies dramatically. The polarization of blazars is of interest for understanding the origin, confinement, and propagation of jets. However, even though numerous measurements have been performed, the mechanisms behind jet creation, composition and variability are still debated. We performed simultaneous gamma-ray and optical photopolarimetry observations of 45 blazars between Jul. 2008 and Dec. 2014 to investigate the mechanisms of variability and search for a basic relation between the several subclasses of blazars. We identify a correlation between the maximum degree of optical linear polarization and the gamma-ray luminosity or the ratio of gamma-ray to optical fluxes. Since the maximum polarization degree depends on the condition of the magnetic field (chaotic or ordered), thi...

  18. Early Optical Polarization of Forward Shock Afterglow of GRB 091208B

    CERN Document Server

    Uehara, T; Kawabata, K S; Chiyonobu, S; Fukazawa, Y; Ikejiri, Y; Inoue, T; Itoh, R; Komatsu, T; Miyamoto, H; Mizuno, T; Nagae, O; Nakaya, H; Ohsugi, T; Sakimoto, K; Sasada, M; Tanaka, H; Uemura, M; Yamanaka, M; Yamashita, T; Yamazaki, R; Yoshida, M

    2012-01-01

    We report that the optical polarization in the afterglow of GRB 091208B is measured at t = 149 - 706 s after the burst trigger, and the polarization degree is P = 10.4% +/- 2.5%. The optical light curve at this time shows a power-law decay with index -0.75 +/- 0.02, which is interpreted as the forward shock synchrotron emission, and thus this is the first detection of the early-time optical polarization in the forward shock (rather than that in the reverse shock reported by Steele et al. (2009). This detection disfavors the afterglow model in which the magnetic fields in the emission region are random on the plasma skin depth scales, such as amplified by the plasma instabilities, e.g., Weibel instability. We suggest that the fields are amplified by the magnetohydrodynamic instabilities, which would be tested by future observations of the temporal changes of the polarization degrees and angles for other bursts.

  19. Cross-polarization in quasi-optical receivers: ALMA band 4 and 10

    Science.gov (United States)

    Gonzalez, A.; Uzawa, Y.

    2012-09-01

    A careful study about the influence of individual optical components on receiver cross-polarization has been performed. The basic mechanisms of generation of cross-polarization in ellipsoidal mirrors and dielectrics have been reviewed and characterized in terms of higher-order Gaussian beam modes. A simple model considering the phase differences of different Gaussian beam modes is proposed in order to calculate the final system cross-polarization pattern. This model has been successfully used to characterize the total cross-polarization in two cryogenically-cooled receivers for astronomy: ALMA band 4 and band 10.

  20. Polarization-independent wavelength conversion using a single semiconductor optical amplifier

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng Xu; Jue Wei; Zhihui Kang; Yun Jiang; Weizhong Zhu; Yunyun Qiao; Jinyue Gao

    2005-01-01

    @@ Polarization-independent wavelength conversion is demonstrated by using four-wave mixing (FWM) in a single semiconductor optical amplifier (SOA). In this scheme, all the incident fields are split into two orthogonal-polarized parts by polarizing beam splitters (PBS). Each of the two parts is then transmitted into one facet of the SOA and they are counter-propagating through the same amplifier. Wavelength conversion with the polarization sensitivity less than 1.3 dB is obtained over a range from 1510 to 1620 nm.

  1. Theoretical Design of Single-Polarization Single- Mode Microstructured Polymer Optical Fibres

    Institute of Scientific and Technical Information of China (English)

    REN Li-Yong; WANG Han-Yi; ZHANG Ya-Ni; YAO Bao-Li; ZHAO Wei

    2007-01-01

    Using the full-vector plane-wave expansion method, a kind of PMMA-based polarization-maintaining microstructured optical fibre (PM-mPOF) is theoretically studied. Dependence of the cutoff wavelengths of the two orthogonal polarization states (polarized along the two principal axes of PM-mPOF) on the structure parameters of the fibre is investigated in detail. A single-polarization single-mode (SPSM) PM-mPOF working in the visible region is designed and optimized with the result of the maximum SPSM bandwidth of 140 nm.

  2. Polarization contrast in fluorescence scanning near-field optical microscopy in reflection

    NARCIS (Netherlands)

    Jalocha, A.; Hulst, van N.F.

    1995-01-01

    Polarization contrast is presented in fluorescence images of a Langmuir-Blodgett monolayer obtained with a scanning near-field optical microscope operated in reflection. A tapered optical fiber is used both to excite and to collect the fluorescence. The lateral resolution in the reflection fluoresce

  3. The high optical polarization in the Be/X-ray binary EXO 2030+375

    CERN Document Server

    Reig, P; Papadakis, I; Kylafis, N; Tassis, K

    2014-01-01

    Polarization in classical Be stars results from Thomson scattering of the unpolarized light from the Be star in the circumstellar disc. Theory and observations agree that the maximum degree of polarization from isolated Be stars is < 4%. We report on the first optical polarimetric observations of the Be/X-ray binary EXO\\,2030+375. We find that the optical (R band) light is strongly linearly polarized with a degee of polarization of 19%, the highest ever measured either in a classical or Be/X-ray binary. We argue that the interstellar medium cannot account for this high polarization degree and that a substantial amount must be intrinsic to the source. We propose that it may result from the alignment of non-spherical ferromagnetic grains in the Be star disc due to the strong neutron star magnetic field.

  4. Novel polarization diversity without switch duplication of a Si-wire PILOSS optical switch.

    Science.gov (United States)

    Tanizawa, Ken; Suzuki, Keijiro; Ikeda, Kazuhiro; Namiki, Shu; Kawashima, Hitoshi

    2016-04-04

    We demonstrate the compact polarization diversity based on the bidirectional full-port use of a path-independent-insertion-loss (PILOSS) optical switch. A polarization-diversity 4 × 4 strictly non-blocking optical switch is developed using a single thermooptic PILOSS Si-wire switch and fiber-based polarization beam splitters (PBSs) and combiners (PBCs). We measure characteristics of the switch and confirm that the proposed configuration demonstrates the performance in the insertion loss, polarization-dependent loss (PDL), and differential group delay (DGD) comparable with that of a conventional polarization-diversity 4 × 4 PILOSS switch using double switch elements. On the other hand, higher crosstalk is observed. The crosstalk increase is associated with the backward crosstalk at a waveguide intersection based on a directional coupler. The effect of the backward crosstalk on the total crosstalk is estimated, and future prospects are discussed.

  5. Characteristics analysis of polarization module on optical proximity effect

    Science.gov (United States)

    Park, Chanha; Hong, Jongkyun; Yang, Kiho; Theeuwes, Thomas; Gautier, Frederic; Min, Young-Hong; Chen, Alek; Yang, Hyunjo; Yim, Donggyu; Kim, Jinwoong

    2007-03-01

    In hyper NA system, specific illumination combined with polarization can be used as one of major RET techniques. Polarization at high NA dry system is also regarded as important technology to bring improvement of very low k1 process. The benefits of polarization on repeated structure are very well known. However we also need to understand the effect on random pattern in peripheral region to adopt polarization technology successfully into real devices. Memory device such as DRAM and NAND Flash has repeated cell structure and also loose pattern in peripheral region. In this study two kinds of polarization function will be applied to real memory devices and the polarization behavior on various patterns in peripheral circuit will be analyzed through actual printing process using 6% attenuated PSM at ArF high NA dry system. The printed result will be compared on random patterns through in-line metrology tool and process guideline including OPC treatment will be discussed based on this study, especially with regard to ID bias.

  6. Monitoring of persistent organic pollutants in the polar regions: knowledge gaps & gluts through evidence mapping.

    Science.gov (United States)

    Mangano, Maria Cristina; Sarà, Gianluca; Corsolini, Simonetta

    2017-04-01

    Persistent organic pollutants (POPs) are widespread compounds that accumulating in polar regions canalise through trophic webs. Although several dozens of studies have been carried out in the last decades, the information is generally scattered across a large number of literature sources. This does not allow an efficient synthesis and constraints our understanding on how address future monitoring plans and environmental conservation strategies on the Polar Regions with respect to POPs. Thus, here, we present the outcome of a systematic map (SM) to scope, screen and chart evidences from literature dealing with POPs in Polar regions. The SMs strive to produce rigorous guidelines and have recently been proposed as useful and effective tools to summarise growing bodies of research that seek to reduce bias and increase reliability, particularly in the case of high priority and controversial topics. Our SM was based on 125 polar studies, focussing on the most studied target species among those listed in the International Union for Conservation of Nature's Red List (IUCN Red List). To facilitate analysis of evidence, the studies were classified into Accumulation Monitoring (accounting for POP monitoring through sub-organismal, functional and population levels) and Food Web Monitoring approaches (accounting for contaminants monitoring through food webs). Our SM allowed us to assess and visualise, a set of both knowledge gaps and gluts and lastly a list was provided to address future research on POPs in Polar Regions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Mathematical modeling and experimental study of polarization echo in optically anisotropic media

    Science.gov (United States)

    Bogdanov, Yu. I.; Kalinkin, A. A.; Kulik, S. P.; Moreva, E. V.; Shershulin, V. A.; Belinsky, L. V.

    2013-01-01

    As optical systems are one of the candidates for implementation of a scalable quantum computer, it is important to develop an adequate method of description of both quantum states of light and operations performed by optical elements. Using the concept of chi-matrix representation of quantum operations and Choi-Jamiolkowski isomorphism we expand Jones calculus to allow description of evolution of mixed polarization states in linear optical systems. The developed method is then used to give a full description of polarization echo effect, which was described in 1 based on an analogy between the effects of polarization optics and spin dynamics. Theoretical predictions are confirmed by reconstructing operations performed by a series of quartz waveplates using quantum process tomography protocols.

  8. Polarization dependent dispersion and its impact on optical parametric process in high nonlinear microstructure fibre

    Institute of Scientific and Technical Information of China (English)

    Xiao Li; Zhang Wei; Huang Yi-Dong; Peng Jiang-De

    2008-01-01

    High nonlinear microstructure fibre (HNMF) is preferred in nonlinear fibre optics, especially in the applications of optical parametric effects, due to its high optical nonlinear coefficient. However, polarization dependent dispersion will impact the nonlinear optical parametric process in HNMFs. In this paper, modulation instability (MI) method is used to measure the polarization dependent dispersion of a piece of commercial HNMF, including the group velocity dispersion, the dispersion slope, the fourth-order dispersion and group birefringence. It also experimentally demonstrates the impact of the polarization dependent dispersion on the continuous wave supercontinuum (SC) generation. On one axis MI sidebands with symmetric frequency dctunings are generated, while on the other axis with larger MI frequency detuning, SC is generated by soliton self-frequency shift.

  9. Optical polarization observations in Hogg 22 and NGC 6204

    Science.gov (United States)

    Martínez, R.; Vergne, M. M.; Feinstein, C.

    2004-06-01

    We present new (UBVRI) multicolor linear polarimetric data for 22 of the brightest stars in the area of the open clusters Hogg 22 and NGC 6204 to study the properties of the ISM (interstellar medium) toward these clusters and between them. The new data were incorporated in our data set of previous observations (Waldhausen et al. \\cite{waldhausen}), resulting in 28 observed stars in the region. Our data yield for NGC 6204 a mean polarization percentage of Pλ_max˜1.8%, close to the polarization value produced by the ISM with normal efficiency (Pλ_max ˜ 5 EB-V) with a color excess of EB-V =0.51. Meanwhile for Hogg 22, located behind NGC 6204, the mean polarization is Pλ_max˜ 2.15%, lower than the expected value for the observed color excess of EB-V =0.68 (Forbes et al. 1996) and the average efficiency of polarization for the interstellar dust. The mean angle of the polarization vectors of Hogg 22 is θ=44.9 °, which agrees with the expected angle produce by dust particles aligned in the direction of the Galactic Plane (θ=48°), while for NGC 6204 a lower value, θ=33.7 °, was found. Therefore, we believe that Hogg 22 is depolarized by the same dust that is polarizing NGC 6204, due to different orientations of the dust particles (and magnetic fields) that polarize the starlight. Based on observations obtanined at Complejo Astronómico El Leoncito (CASLEO), operated under agreement between the CONICET and the National Universities of La Plata, Córdoba, and San Juan, Argentina.

  10. Apparatus and Method for Elimination of Polarization-Induced Fading in Fiber-optic Sensor System

    Science.gov (United States)

    Chan, Hon Man (Inventor); Parker, Jr., Allen R. (Inventor)

    2015-01-01

    The invention is an apparatus and method of eliminating polarization-induced fading in interferometric fiber-optic sensor system having a wavelength-swept laser optical signal. The interferometric return signal from the sensor arms are combined and provided to a multi-optical path detector assembly and ultimately to a data acquisition and processing unit by way of a switch that is time synchronized with the laser scan sweep cycle.

  11. All-optical D and T flip-flops based on polarization switch of SOA

    Science.gov (United States)

    Wang, Lina; Wang, Yongjun; Wu, Chen

    2016-11-01

    The semiconductor optical amplifier (SOA) plays an important role in the development of the all-optical signal processing because of the advantages of simple structure, easy integration and strong non-linearity. Especially the nonlinear polarization rotation effect of SOA is receiving considerable interest by many researchers nowadays. The all-optical flip-flop using the properties of SOA also obtains widespread attention by researchers, as all-optical flip-flop is an important part in the field of all-optical signal processing. In this paper, a new all-optical flip-flop structure using polarization switch (PSW) based on polarization rotation effect of SOA is presented. The main work of the paper is the simulation of all-optical logic gates and optical SR latch. The logic gate setup only uses one SOA, but it can get two different logic gates through a simulation. The extinction ratio of the logic gate is about 30dB. The structure of optical SR latch utilizes the two coupled polarization rotation switch of SOA. The structure of the flip-flop is based on these two parts. To demonstrate the feasibility of the structure, we analyze two types of flip-flops, including all-optical D and T flip-flops, whose clock pulse repetition rate is 1GHz with the pulse width of 0.3ns. The quality of all-optical flip-flop in this paper is measured by the falling and rising edge time. In the simulation, the falling edge time is about 50ps, while the rising edge time is higher than the falling edge time, because the gain increases slowly to the recovery time after the decrease of the gain of SOA. The results are useful for the development of all-optical flip-flop based on SOA.

  12. Free Space Optical Polarization De-multiplexing and Multiplexing by means of Conical Refraction

    OpenAIRE

    Turpin Avilés, Alejandro; Loiko, Yurii; Kalkandjiev, Todor Kirilov; Mompart Penina, Jordi

    2013-01-01

    Polarization demultiplexing and multiplexing by means of conical refraction is proposed to increase the channel capacity for free-space optical communication applications. The proposed technique is based on the forward-backward optical transform occurring when a light beam propagates consecutively along the optic axes of two identical biaxial crystals with opposite orientations of their conical refraction characteristic vectors. We present an experimental proof of usefulness of the conical re...

  13. An optically remote powered subsea video monitoring system

    Science.gov (United States)

    Lau, Fat Kit; Stewart, Brian; McStay, Danny

    2012-06-01

    The drive for Ocean pollution prevention requires a significant increase in the extent and type of monitoring of subsea hydrocarbon production equipment. Sensors, instrumentation, control electronics, data logging and transmission units comprising such monitoring systems will all require to be powered. Conventionally electrical powering is supplied by standard subsea electrical cabling. The ability to visualise the assets being monitored and any changes or faults in the equipment is advantageous to an overall monitoring system. However the effective use of video cameras, particularly if the transmission of real time high resolution video is desired, requires a high data rate and low loss communication capability. This can be challenging for heavy and costly electrical cables over extended distances. For this reason optical fibre is often adopted as the communication channel. Using optical fibre cables for both communications and power delivery can also reduce the cost of cabling. In this paper we report a prototype optically remote powered subsea video monitoring system that provides an alternative approach to powering subsea video cameras. The source power is transmitted to the subsea module through optical fibre with an optical-to-electrical converter located in the module. To facilitate intelligent power management in the subsea module, a supercapacitor based intermediate energy storage is installed. Feasibility of the system will be demonstrated. This will include energy charging and camera operation times.

  14. Highly precise and accurate terahertz polarization measurements based on electro-optic sampling with polarization modulation of probe pulses.

    Science.gov (United States)

    Nemoto, Natsuki; Higuchi, Takuya; Kanda, Natsuki; Konishi, Kuniaki; Kuwata-Gonokami, Makoto

    2014-07-28

    We have developed an electro-optic (EO) sampling method with polarization modulation of probe pulses; this method allows us to measure the direction of a terahertz (THz) electric-field vector with a precision of 0.1 mrad in a data acquisition time of 660 ms using a 14.0-kHz repetition rate pulsed light source. Through combination with a THz time-domain spectroscopy technique, a time-dependent two-dimensional THz electric field was obtained. We used a photoelastic modulator for probe-polarization modulation and a (111)-oriented zincblende crystal as the EO crystal. Using the tilted pulse front excitation method with stable regeneratively amplified pulses, we prepared stable and intense THz pulses and performed pulse-by-pulse analog-to-digital conversion of the signals. These techniques significantly reduced statistical errors and enabled sub-mrad THz polarization measurements. We examined the performance of this method by measuring a wire-grid polarizer as a sample. The present method will open a new frontier of high-precision THz polarization sensitive measurements.

  15. Optical Polarization M\\"obius Strips and Points of Purely Transverse Spin Density

    CERN Document Server

    Bauer, Thomas; Leuchs, Gerd; Banzer, Peter

    2016-01-01

    Tightly focused light beams can exhibit electric fields spinning around any axis including the one transverse to the beams' propagation direction. At certain focal positions, the corresponding local polarization ellipse can degenerate into a perfect circle, representing a point of circular polarization, or C-point. We consider the most fundamental case of a linearly polarized Gaussian beam, where - upon tight focusing - those C-points created by transversely spinning fields can form the center of 3D optical polarization topologies when choosing the plane of observation appropriately. Due to the high symmetry of the focal field, these polarization topologies exhibit non trivial structures similar to M\\"obius strips. We use a direct physical measure to find C-points with an arbitrarily oriented spinning axis of the electric field and experimentally investigate the fully three-dimensional polarization topologies surrounding these C-points by exploiting an amplitude and phase reconstruction technique.

  16. Wavelength Dependence of the Polarization Singularities in a Two-Mode Optical Fiber

    Directory of Open Access Journals (Sweden)

    V. V. G. Krishna Inavalli

    2012-01-01

    Full Text Available We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength—from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned.

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

    Science.gov (United States)

    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.

  18. Nuclear spin polarized H and D by means of spin-exchange optical pumping

    Science.gov (United States)

    Stenger, Jörn; Grosshauser, Carsten; Kilian, Wolfgang; Nagengast, Wolfgang; Ranzenberger, Bernd; Rith, Klaus; Schmidt, Frank

    1998-01-01

    Optically pumped spin-exchange sources for polarized hydrogen and deuterium atoms have been demonstrated to yield high atomic flow and high electron spin polarization. For maximum nuclear polarization the source has to be operated in spin temperature equilibrium, which has already been demonstrated for hydrogen. In spin temperature equilibrium the nuclear spin polarization PI equals the electron spin polarization PS for hydrogen and is even larger than PS for deuterium. We discuss the general properties of spin temperature equilibrium for a sample of deuterium atoms. One result are the equations PI=4PS/(3+PS2) and Pzz=PSṡPI, where Pzz is the nuclear tensor polarization. Furthermore we demonstrate that the deuterium atoms from our source are in spin temperature equilibrium within the experimental accuracy.

  19. Comparative study of optical fiber cure-monitoring methods

    Science.gov (United States)

    Crosby, Peter A.; Powell, Graham R.; Fernando, Gerard F.; Waters, David N.; France, Chris M.; Spooncer, Ronald C.

    1997-06-01

    This paper reports on a comparative study undertaken for different types of optical fiber sensor developed to monitor the cure of an epoxy resin system. The optical fiber sensors used to monitor the cure process were based on transmission spectroscopy, evanescent wave spectroscopy and refractive index monitoring. The transmission sensor was prepared by aligning two optical fibers within a specially prepared sleeve with a gap between the optical fiber end-faces. During cure, resin from the specimen flowed into the gap between the optical fibers allowing transmission spectra of the resin to be obtained. The evanescent wave sensor was prepared by stripping the cladding from a high refractive index core optical fiber. The prepared sensor was embedded in the sample and attenuated total reflectance spectra recorded from the resin/core boundary. Refractive index monitoring was undertaken using a high refractive index core optical fiber which had a small portion of its cladding removed. The prepared sensor was embedded in the resin specimen and light from a single wavelength source was launched into the fiber. Changes in the guiding characteristics of the sensor due to refractive index changes at the resin/core boundary were used to monitor the progress of the cure reaction. The transmission and evanescent wave spectroscopy sensors were used to follow changes in characteristic near-infrared absorption bands of the resin over the range 1450 - 1700 nm during the cure reaction. Consequently these techniques required tunable wavelength sources covering specific wavelength ranges. However, the refractive index based sensor used a single wavelength source. Therefore the equipment costs for this type of sensor were considerably less. Additionally, the refractive index sensor did not require a single wavelength source at any particular wavelength and could be applied to any spectral region in which the optical fiber would transmit light. The advantages and disadvantages of these

  20. Quantifying the polarization properties of non-depolarizing optical elements with virtual distorting elements.

    Science.gov (United States)

    Wang, Xiao; Yang, Feng; Yin, Jianhua

    2017-04-01

    It is well known that polarization can be potentially distorted by optical elements in optical paths, which intensively influences researches and techniques related to polarization analysis. For this, we proposed to exactly quantify the polarization properties of non-depolarizing optical elements with virtual distorting elements characterized by three parameters: orientation Θ, diattenuation Γ, and retardation Δ. Utilizing the least-squares fitting method, these three parameters can be determined by fitting the measured output polarization states from the optical element with the polarization responses of VDEs. The principle of this method is detailed, and a corresponding experimental setup is further presented. The feasibility of this method has been verified in reflective mirrors and a dichroic mirror. Based on the quantification results with our setup, we have successfully compensated the polarization distortion induced by a dichroic mirror. The precision of this method has been investigated in detail with Monte Carlo simulations. The investigation results show that this method has high precision at certain measurement conditions, and the precision can be further improved.

  1. FIBER OPTIC SENSORS FOR ENVIRONMENTAL MONITORING

    Science.gov (United States)

    Due to decades of neglect as well as ever-increasing industrial activity, environmental monitoring has become an important issue. Given the expense and time constraints associated with classical laboratory analysis, there exists a growing interest in cost-effective and real-time ...

  2. Generation and dynamics of optical beams with polarization singularities

    CERN Document Server

    Cardano, Filippo; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

    2013-01-01

    We present a convenient method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell. The resulting polarization patterns exhibit a C-point on the beam axis and an L-line loop around it, and may have different geometrical structures such as \\qo{lemon}, \\qo{star}, and \\qo{vortex}. Our generation method allows us to control the radius of L-line loop around the central C-point. Moreover, we investigate the free-air propagation of these fields across a Rayleigh range.

  3. Generation and dynamics of optical beams with polarization singularities.

    Science.gov (United States)

    Cardano, Filippo; Karimi, Ebrahim; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

    2013-04-08

    We present a convenient method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell. The resulting polarization patterns exhibit a C-point on the beam axis and an L-line loop around it, and may have different geometrical structures such as "lemon", "star", and "spiral". Our generation method allows us to control the radius of L-line loop around the central C-point. Moreover, we investigate the free-air propagation of these fields across a Rayleigh range.

  4. Polarization-selective optical nonlinearities in cold Rydberg atoms

    Science.gov (United States)

    Wu, Jin-Hui; Artoni, M.; La Rocca, G. C.

    2015-12-01

    We study the interaction between a probe and a trigger weak fields in a sample of cold rubidium atoms in the presence of a coupling and a dressing strong fields. Dipole Rydberg blockade may occur and can be set to depend on the probe and trigger polarizations giving rise to diverse regimes of electromagnetically induced transparency (EIT) with a concomitant small probe and trigger absorption and dispersion. This is shown to be relevant to the implementation of polarization conditional probe and trigger cross nonlinearities in cold Rydberg atoms.

  5. Optical tools for ocean monitoring and research

    Directory of Open Access Journals (Sweden)

    C. Moore

    2009-12-01

    Full Text Available Requirements for understanding the relationships between ocean color and suspended and dissolved materials within the water column, and a rapidly emerging photonics and materials technology base for performing optical based analytical techniques have generated a diverse offering of commercial sensors and research prototypes that perform optical measurements in water. Through inversion, these tools are now being used to determine a diverse set of related biogeochemical and physical parameters. Techniques engaged include measurement of the solar radiance distribution, absorption, scattering, stimulated fluorescence, flow cytometry, and various spectroscopy methods. Selective membranes and other techniques for material isolation further enhance specificity, leading to sensors for measurement of dissolved oxygen, methane, carbon dioxide, common nutrients and a variety of other parameters. Scientists are using these measurements to infer information related to an increasing set of parameters and wide range of applications over relevant scales in space and time.

  6. X-ray monitoring optical elements

    Energy Technology Data Exchange (ETDEWEB)

    Stoupin, Stanislav; Shvydko, Yury; Katsoudas, John; Blank, Vladimir D.; Terentyev, Sergey A.

    2016-12-27

    An X-ray article and method for analyzing hard X-rays which have interacted with a test system. The X-ray article is operative to diffract or otherwise process X-rays from an input X-ray beam which have interacted with the test system and at the same time provide an electrical circuit adapted to collect photoelectrons emitted from an X-ray optical element of the X-ray article to analyze features of the test system.

  7. Passive optical sensing of atmospheric polarization for GPS denied operations

    Science.gov (United States)

    Aycock, Todd; Lompado, Art; Wolz, Troy; Chenault, David

    2016-05-01

    There is a rapidly growing need for position, navigation, and timing (PNT) capability that remains effective when GPS is degraded or denied. Naturally occurring sky polarization was used as long ago as the Vikings for navigation purposes. With current polarimetric sensors, the additional polarization information measured by these sensors can be used to increase the accuracy and the availability of this technique. The Sky Polarization Azimuth Sensing System (SkyPASS) sensor measures this naturally occurring sky polarization to give absolute heading information to less than 0.1° and offers significant performance enhancement over digital compasses and sun sensors. SkyPASS has been under development for some time for terrestrial applications, but use above the atmosphere may be possible and the performance specifications and SWAP are attractive for use as an additional pose sensor on a satellite. In this paper, we will describe the phenomenology, the sensor performance, and the latest test results of terrestrial SkyPASS; we will also discuss the potential for use above the atmosphere and the expected benefits and limitations.

  8. Towards all-dielectric, polarization-independent optical cloaks

    DEFF Research Database (Denmark)

    Andkjær, Jacob Anders; Mortensen, N. Asger; Sigmund, Ole

    2012-01-01

    Fully enclosing, all-dielectric cloaks working for both E-z and H-z polarizations simultaneously are presented in this letter. The cloaks are effective for two antiparallel angles of incidence, and the layout of standard dielectric material in the cloak is determined by topology optimization...

  9. Cross-polarization endoscopic optical coherence tomography in urology

    Science.gov (United States)

    Zagaynova, E. V.; Gladkova, N. D.; Gelikonov, V. M.; Streltsova, O. S.; Ledayev, D. S.; Atduev, V. A.; Balandina, E. V.; Snopova, L. B.

    2009-02-01

    We present results obtained using a two-channel portable device for CP OCT based on the polarization-maintaining fiber. The device is capable of acquiring OCT images of the object in direct and orthogonal polarizations simultaneously. The OCT system has an endoscopic forward-looking probe (2.7 mm in diameter). The CP OCT imaging was done in 64 postoperative specimens, for 30 patients during cystoscopy with suspicion of urothelial neoplasia, and for 11 patients with prostatectomy due to cancer. After surgery in the tissue specimen we immediately introduced surgical suture and investigated a bladder wall by CP OCT. When comparing OCT images and histology slides we can distinguish tissue layers based on position of the suture material. CP OCT images were compared with histological data. Special staining - Sirius Red for collagen types was applied. OCT -visualization of sympathetic nerve was made during open surgery. We found, that a strong signal in orthogonal polarization is produced by structures consisting of Type I collagen. We demonstrated that endoscopic benign and early malignant pathological processes that cannot be detected by standard OCT may be differentiated by CP OCT. Sympathetic nerve of neurovascular bundle gives a strong signal in both polarizations: direct and orthogonal. Based on these CP OCT features we can visualize nerve during operation (open or endoscopic surgery) and thus preserve it.

  10. Limits on optical polarization during the prompt phase of GRB 140430A

    CERN Document Server

    Kopac, D; Japelj, J; Arnold, D M; Steele, I A; Guidorzi, C; Dichiara, S; Kobayashi, S; Gomboc, A; Harrison, R M; Lamb, G P; Melandri, A; Smith, R J; Virgili, F J; Castro-Tirado, A J; Gorosabel, J; Jarvinen, A; Sanchez-Ramirez, R; Oates, S R; Jelinek, M

    2015-01-01

    Gamma-ray burst GRB 140430A was detected by the Swift satellite and observed promptly with the imaging polarimeter RINGO3 mounted on the Liverpool Telescope, with observations beginning while the prompt $\\gamma$-ray emission was still ongoing. In this paper, we present densely sampled (10-second temporal resolution) early optical light curves in 3 optical bands and limits to the degree of optical polarization. We compare optical, X-ray and gamma-ray properties and present an analysis of the optical emission during a period of high-energy flaring. The complex optical light curve cannot be explained merely with a combination of forward and reverse shock emission from a standard external shock, implying additional contribution of emission from internal shock dissipation. We estimate an upper limit for time averaged optical polarization during the prompt phase to be as low as P < 12% (1$\\sigma$). This suggests that the optical flares and early afterglow emission in this GRB are not highly polarized. Alternativ...

  11. Advances in fiber optic sensors for in-vivo monitoring

    Science.gov (United States)

    Baldini, Francesco; Mignani, Anna G.

    1995-09-01

    Biomedical fiber-optic sensors are attractive for the measurement of both physical and chemical parameters as well as for spectral measurements directly performed on the patient. An overview of fiber-optic sensors for in vivo monitoring is given, with particular attention to the advantages that these sensors are able to offer in different fields of application such as cardiovascular and intensive care, angiology, gastroenterology, ophthalmology, oncology, neurology, dermatology, and dentistry.

  12. Crack monitoring capability of plastic optical fibers for concrete structures

    Science.gov (United States)

    Zhao, Jinlei; Bao, Tengfei; Chen, Rui

    2015-08-01

    Optical fibers have been widely used in structural health monitoring. Traditional silica fibers are easy to break in field applications due to their brittleness. Thus, silica fibers are proposed to be replaced by plastic optical fibers (POFs) in crack monitoring in this study. Moreover, considering the uncertainty of crack propagation direction in composite materials, the influence of the angles between fibers and cracks on the monitoring capability of plastic optical fibers is studied. A POF sensing device was designed and the relationship between light intensity loss and crack width under different fiber/crack angles was first measured through the device. Then, three-point bend tests were conducted on concrete beams. POFs were glued to the bottom surfaces of the beams and light intensity loss with crack width was measured. Experimental results showed that light intensity loss in plastic optical fibers increased with crack width increase. Therefore, application of plastic optical fibers in crack monitoring is feasible. Moreover, the results also showed that the sensitivity of the POF crack sensor decreased with the increase of angles between fibers and cracks.

  13. Circular polarization intrinsic optical signal recording of stimulus-evoked neural activity.

    Science.gov (United States)

    Lu, Rong-Wen; Zhang, Qiu-Xiang; Yao, Xin-Cheng

    2011-05-15

    Linear polarization intrinsic optical signal (LP-IOS) measurement can provide sensitive detection of neural activities in stimulus-activated neural tissues. However, the LP-IOS magnitude and signal-to-noise ratio (SNR) are highly correlated with the nerve orientation relative to the polarization plane of the incident light. Because of the complexity of orientation dependency, LP-IOS optimization and outcome interpretation are time consuming and complicated. In this study, we demonstrate the feasibility of circular polarization intrinsic optical signal (CP-IOS) measurement. Our theoretical modeling and experimental investigation indicate that CP-IOS magnitude and SNR are independent from the nerve orientation. Therefore, CP-IOS promises a practical method for polarization IOS imaging of complex neural systems.

  14. Optical asymmetric cryptography based on elliptical polarized light linear truncation and a numerical reconstruction technique.

    Science.gov (United States)

    Lin, Chao; Shen, Xueju; Wang, Zhisong; Zhao, Cheng

    2014-06-20

    We demonstrate a novel optical asymmetric cryptosystem based on the principle of elliptical polarized light linear truncation and a numerical reconstruction technique. The device of an array of linear polarizers is introduced to achieve linear truncation on the spatially resolved elliptical polarization distribution during image encryption. This encoding process can be characterized as confusion-based optical cryptography that involves no Fourier lens and diffusion operation. Based on the Jones matrix formalism, the intensity transmittance for this truncation is deduced to perform elliptical polarized light reconstruction based on two intensity measurements. Use of a quick response code makes the proposed cryptosystem practical, with versatile key sensitivity and fault tolerance. Both simulation and preliminary experimental results that support theoretical analysis are presented. An analysis of the resistance of the proposed method on a known public key attack is also provided.

  15. Polar Sea Ice Monitoring Using HY-2A Scatterometer Measurements

    Directory of Open Access Journals (Sweden)

    Mingming Li

    2016-08-01

    Full Text Available A sea ice detection algorithm based on Fisher’s linear discriminant analysis is developed to segment sea ice and open water for the Ku-band scatterometer onboard the China’s Hai Yang 2A Satellite (HY-2A/SCAT. Residual classification errors are reduced through image erosion/dilation techniques and sea ice growth/retreat constraint methods. The arctic sea-ice-type classification is estimated via a time-dependent threshold derived from the annual backscatter trends based on previous HY-2A/SCAT derived sea ice extent. The extent and edge of the sea ice obtained in this study is compared with the Special Sensor Microwave Imager/Sounder (SSMIS sea ice concentration data and the Sentinel-1 SAR imagery for verification, respectively. Meanwhile, the classified sea ice type is compared with a multi-sensor sea ice type product based on data from the Advanced Scatterometer (ASCAT and SSMIS. Results show that HY-2A/SCAT is powerful in providing sea ice extent and type information, while differences in the sensitivities of active/passive products are found. In addition, HY-2A/SCAT derived sea ice products are also proved to be valuable complements for existing polar sea ice data products.

  16. Analysis of aerosol optical depth evaluation in polar regions and associated uncertainties

    Directory of Open Access Journals (Sweden)

    P. Ortiz de Galisteo

    2008-04-01

    Full Text Available Some available processing algorithms used to calculate the aerosol optical depth from radiometric measurements were tested. The aim was to evaluate the associated uncertainties in polar regions due to the data processing, in order to adjust the methodology of the calculation and illustrate the importance of these error sources. The measurements were obtained during a sun photometer campaign in Ny-Ålesund within the framework of the POLAR-AOD project.

  17. Optical broadband monitoring of thin film growth

    Institute of Scientific and Technical Information of China (English)

    H.Ehlers; T.Groβ; M.Lappschies; D.Ristau

    2005-01-01

    This contribution is focused on applications of spectroscopic methods for the precise control of deposition processes. In this context, the present study gives a review on selected combinations of conventional and ion deposition techniques with different broadband online spectrophotometric systems. Besides two systems operating in the VIS- and NIR-spectral range in combination with ion processes, also a monochromator system developed for conventional deposition processes in the DUV/VUV-spectral range will be discussed. The considerations will be concluded by a comparison of the major advantages of the specific combinations of processes with online monitoring concepts and by a brief outlook concerning future challenges.

  18. Optical resonance on LIPSS sensed by polarized light

    Science.gov (United States)

    Silvennoinen, Martti; HasoÅ, Stanislav; Silvennoinen, Raimo

    2013-12-01

    Non-symmetric and directional reflectivity from three dimensional (3D) laser induced periodic surface structures (LIPSS) is considered. LIPSS structures were patterned in stainless steel (W720) by using linear and elliptical polarized laser beams from a femtosecond (fs) laser. The short and long periodic ripples and possible other type artifact remaining has decreasing influences to relative reflectivity variation between 5% and 65% in the wavelength range from 200nm to 800nm. The studies of patterned W720LIPSS structures indicated, besides of increased surface area, that decrease of reflectivity is affected by light scattering from ultra-structures of LIPSS and produces resonance type differences in spectral reflectivity when either TM or TE polarized probing beam interacts with micro- and ultrastructure of LIPSS.

  19. Compact Hybrid Subsystem of 16 Channel Optical Demultiplexer, 2x2 Switches, Optical Power Monitors and Control Circuit

    Institute of Scientific and Technical Information of China (English)

    Kenichiro Takahashi; Toshihiko Kishimoto; Shintaro Mouri; Youichi Hata; Hideaki Yusa; Mitsuaki Tamura; Kazuhito Saito; Hisao Maki

    2003-01-01

    A compact hybrid subsystem of 16channel optical demultiplexer, 2x2 switches, optical power monitors and control circuit board is developed. The subsystem is able to add or drop arbitrary optical channels and monitor the optical power level by software commands. The size of the subsystem is 170x200x30(mm).

  20. Ultrafast polarization optical switch constructed from one-dimensional photonic crystal and its performance analysis

    Institute of Scientific and Technical Information of China (English)

    WANG Tao; LI Qing; GAO DingShan

    2009-01-01

    All-optical switch with the ultrafast optical switching rate is a key device in the next generation optical network. In this article, we propose a polarization switch with ps switching time, which is constructed from one-dimensional resonant photonic crystal (1D RPC). The model of switch operating at 1.5 μm is established based on the optical stark effect (OSE). We calculate the performance indices of the switch and the influences of errors of periods and refractive index on the performance characteristics.

  1. Free-space optical polarization demultiplexing and multiplexing by means of conical refraction.

    Science.gov (United States)

    Turpin, Alex; Loiko, Yurii; Kalkandjiev, Todor K; Mompart, Jordi

    2012-10-15

    Polarization demultiplexing and multiplexing by means of conical refraction is proposed to increase the channel capacity for free-space optical communication applications. The proposed technique is based on the forward-backward optical transform occurring when a light beam propagates consecutively along the optic axes of two identical biaxial crystals with opposite orientations of their conical refraction characteristic vectors. We present an experimental proof of usefulness of the conical refraction demultiplexing and multiplexing technique by increasing in one order of magnitude the channel capacity at optical frequencies in a propagation distance of 4 m.

  2. Polarized spectral combs probe optical fiber surface plasmons.

    Science.gov (United States)

    Caucheteur, Christophe; Voisin, Valérie; Albert, Jacques

    2013-02-11

    The high-order cladding modes of conventional single mode fiber come in semi-degenerate pairs corresponding to mostly radially or mostly azimuthally polarized light. Using tilted fiber Bragg gratings to excite these mode families separately, we show how plasmonic coupling to a thin gold coating on the surface of the fiber modifies the effective indices of the modes differently according to polarization and to mode order. In particular, we show the existence of a single "apolarized" grating resonance, with equal effective index for all input polarization states. This special resonance provides direct evidence of the excitation of a surface plasmon on the metal surface but also an absolute wavelength reference that allows for the precise localization of the most sensitive resonances in refractometric and biochemical sensing applications. Two plasmon interrogation methods are proposed, based on wavelength and amplitude measurements. Finally, we use a biotin-streptavidin biomolecular recognition experiment to demonstrate that differential spectral transmission measurements of a fine comb of cladding mode resonances in the vicinity of the apolarized resonance provide the most accurate method to extract information from plasmon-assisted Tilted fiber Bragg gratings, down to pM concentrations and at least 10(-5) refractive index changes.

  3. A novel optical scattering collection system for particulate monitoring applications

    Energy Technology Data Exchange (ETDEWEB)

    Bernacki, B.E.; Miller, A.C. Jr. [Oak Ridge National Lab., TN (United States); Nuspliger, R.J. [Environmental Systems Corp., Knoxville, TN (United States)

    1996-05-01

    Light collecting systems often require radically different optical surfaces than those commonly found in optical imaging systems. An optical particulate monitor must probe a volume in emission stacks to obtain a good statistical distribution of suspended particles. However, ideal imaging systems map object planes into conjugate image planes and can probe only small volumes. The authors describe the design, fabrication and performance of a novel optical scattering collection system that exploits precision-engineered reflective conical surfaces (axicons) in a telescopic arrangement that maps a line in object space onto the detector plane in image space. Such non-spherical surfaces are nearly impossible to fabricate using traditional methods, but can readily be made using the deterministic method of single-point diamond turning. In addition to complex optical surfaces, single-point diamond turning also makes possible the precision engineering of reference surfaces useful for built-in alignment of multiple surfaces and rapid assembly of the finished system.

  4. Development and demonstration of optical polarization controller; Hikari henpa seigyo sochi no kaihatsu to jissho

    Energy Technology Data Exchange (ETDEWEB)

    Kurono, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1997-04-01

    If fiber transmission light can be controlled in a stabilized polarization state, realization of coherent optical communication is anticipated. In the case of adopting it to OPGW, however, it is necessary to compensate high speed polarization variation caused by lightning strike. But this was difficult in the conventional method. Accordingly, a high speed polarization control method was proposed which uses an electric effect of lithium niobate (LN) crystals. In the study, a polarization control unit was manufactured based on the method proposed and the performance was demonstrated. As a result of measuring output light with input light changed in every state of polarization, the object horizontal polarization component obtained a stabilized light intensity at {+-}0.1dB, and a light intensity of the component slipped out of the horizontal polarization was suppressed under -20dB. To cope with the polarization variation by lightning strike, it is necessary to make the control delay 10{mu}sec or below, and improvement in processing unit, etc. may make it possible since LN crystals respond below 1{mu}sec. High speed control of the infinitely continuing arbitrary polarization variation became possible. 14 refs., 19 figs.

  5. Long-term optical polarization variability of the tev blazar 1es~1959+650

    CERN Document Server

    Sorcia, Marco; Hiriart, David; López, José M; Cabrera, José I; Mújica, Raúl; Heidt, Jochen; Agudo, Ivan; Nilsson, Kari; Mommert, Michael

    2013-01-01

    A detailed analysis of the optical polarimetric variability of the TeV blazar 1ES 1959+650 from 2007 October 18 to 2011 May 5 is presented. The source showed a maximum and minimum brightness states in the R-band of 14.08$\\pm$0.03 mag and 15.20$\\pm$0.03 mag, respectively, with a maximum variation of 1.12 mag, and also a maximum polarization degree of $P=$(12.2$\\pm$0.7)%, with a maximum variation of 10.7%. From August to November 2009, a correlation between the optical $R$-band flux and the degree of linear polarization was found, with a correlation coefficient $r_{pol}$=0.984$\\pm$0.025. The source presented a preferential position angle of optical polarization of $\\sim153^{\\circ}$, with variations of $10\\degr$-$50\\degr$, that is in agreement with the projected position angle of the parsec scale jet found at 43 GHz. From the Stokes parameters we infer the existence of two optically-thin synchrotron components that contribute to the polarized flux. One of them is stable, with a constant polarization degree of 4%...

  6. Optical modeling and polarization calibration for CMB measurements with ACTPol and Advanced ACTPol

    CERN Document Server

    Koopman, Brian; Cho, Hsiao-Mei; Coughlin, Kevin P; Duff, Shannon M; Gallardo, Patricio A; Hasselfield, Matthew; Henderson, Shawn W; Ho, Shuay-Pwu Patty; Hubmayr, Johannes; Irwin, Kent D; Li, Dale; McMahon, Jeff; Nati, Federico; Niemack, Michael D; Newburgh, Laura; Page, Lyman A; Salatino, Maria; Schillaci, Alessandro; Schmitt, Benjamin L; Simon, Sara M; Vavagiakis, Eve M; Ward, Jonathan T; Wollack, Edward J

    2016-01-01

    The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive upgrade to the Atacama Cosmology Telescope. Located at an elevation of 5190 m, ACTPol measures the Cosmic Microwave Background (CMB) temperature and polarization with arcminute-scale angular resolution. Calibration of the detector angles is a critical step in producing maps of the CMB polarization. Polarization angle offsets in the detector calibration can cause leakage in polarization from E to B modes and induce a spurious signal in the EB and TB cross correlations, which eliminates our ability to measure potential cosmological sources of EB and TB signals, such as cosmic birefringence. We present our optical modeling and measurements associated with calibrating the detector angles in ACTPol.

  7. Focusing light through scattering media by full-polarization digital optical phase conjugation.

    Science.gov (United States)

    Shen, Yuecheng; Liu, Yan; Ma, Cheng; Wang, Lihong V

    2016-03-15

    Digital optical phase conjugation (DOPC) is an emerging technique for focusing light through or within scattering media such as biological tissue. Since DOPC systems are based on time reversal, they benefit from collecting as much information about the scattered light as possible. However, existing DOPC techniques record and subsequently phase-conjugate the scattered light in only a single-polarization state, limited by the operating principle of spatial light modulators. Here, we develop the first, to the best of our knowledge, full-polarization DOPC system that records and phase-conjugates scattered light along two orthogonal polarizations. When focusing light through thick scattering media, such as 2 mm and 4 mm-thick chicken breast tissue, our full-polarization DOPC system on average doubles the focal peak-to-background ratio achieved by single-polarization DOPC systems and improves the phase-conjugation fidelity.

  8. Sign reversal of Hanle electromagnetically induced absorption with orthogonal circularly polarized optical fields

    Energy Technology Data Exchange (ETDEWEB)

    Ram, Nibedita; Pattabiraman, M, E-mail: pattu@physics.iitm.ac.i [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

    2010-12-28

    We study by computation and experiment an electromagnetically induced absorption resonance in the Hanle configuration with a transverse magnetic field on a closed F{sub g} {yields} F{sub e} = F{sub g}+1 transition with co-propagating orthogonal circularly polarized probe and coupling optical fields. At high coupling field intensities, the Hanle resonance changes sign due to a shift in atomic population from Zeeman sublevels associated with a probe field cyclic transition to sublevels associated with a coupling field cyclic transition at zero magnetic field. We also show that a similar sign reversal does not occur for {pi}-polarized and {sigma}-polarized coupling fields.

  9. Control of polarization-induced stiffness asymmetry in highly focused optical tweezers

    CERN Document Server

    So, Jinmyoung

    2015-01-01

    Optical tweezers that utilize a highly focused, linearly polarized laser beam are shown to exhibit strong stiffness asymmetry, which originates from the anisotropic field distribution in the transverse plane. We present an experimental demonstration in which the degree of stiffness asymmetry is controlled by using the polarization state of the trapping beam as a tuning knob. Theoretical support for the experimental observations is provided based on the generalized Lorenz-Mie theory, which is revised to encompass the general polarization state of a trapping beam.

  10. Generation of radially and azimuthally polarized light by optical transmission through concentric circular nanoslits in Ag films.

    Science.gov (United States)

    Wang, Feng; Xiao, Min; Sun, Kai; Wei, Qi-Huo

    2010-01-04

    Optical transmission through concentric circular nanoslits is studied in experiments and numerical simulations. Polarized optical microscopic imaging shows that the optical transmission through these apertures is spatially inhomogeneous, exhibiting colored fan texture patterns. Numerical simulations show that these colored fan texture patterns originate from the cylindrical vector polarization of the transmitted beam. Specifically, the transmitted light is in-phase radially polarized at long wavelengths due to the predominant transmission of the transverse magnetic (TM) waveguide modes; and in-phase azimuthally polarized at short wavelengths due to the increased optical transmission of the transverse electric (TE) waveguide modes. Additionally, the transmission shows a peak at the wavelength of Wood anomaly and a dip at the resonant wavelength of surface plasmon excitation; and the transmitted light at these wavelengths is a mixture of azimuthally and radially polarized fields. These interesting optical transmission behaviors of circular nanoslits provide a miniaturized way to generating radially and azimuthally polarized light.

  11. Control of light polarization using optically spin-injected vertical external cavity surface emitting lasers

    Energy Technology Data Exchange (ETDEWEB)

    Frougier, J., E-mail: julien.frougier@thalesgroup.com; Jaffrès, H.; Deranlot, C.; George, J.-M. [Unité Mixte de Physique CNRS-Thales and Université Paris Sud 11, 1 av. Fresnel, 91767 Palaiseau (France); Baili, G.; Dolfi, D. [Thales Research and Technology, 1 av. Fresnel, 91767 Palaiseau (France); Alouini, M. [Institut de Physique de Rennes, 263 Avenue Général Leclerc, 35042 Rennes (France); Sagnes, I. [Laboratoire de Photonique et de Nanostructures, Route de Nozay, 91460 Marcoussis (France); Garnache, A. [Institut d' électronique du Sud CNRS UMR5214, Université Montpellier 2 Place Eugene Bataillon, 34095 Montpellier (France)

    2013-12-16

    We fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well Vertical External Cavity Surface Emitting Laser (VECSEL). The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the electromagnetic field polarization using optical spin injection in the active medium of the VECSEL. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This result witnesses an efficient spin-injection in the active medium of the LASER.

  12. Plasmonic Dimer Metamaterials and Metasurfaces for Polarization Control of Terahertz and Optical Waves

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Zalkovskij, Maksim; Malureanu, Radu

    2013-01-01

    We explore the capabilities of planar metamaterials and metasurfaces to control and transform the polarization of electromagnetic radiation, and present a detailed covariant multipole theory of dimer-based metamaterials. We show that various optical properties, such as optical activity, elliptical...... dichroism or polarization conversion can be achieved in metamaterials made of simple shapes, such as nanorods, just by varying their geometrical arrangement. By virtue of the Babinet principle, the proposed theory is extended to inverted structures (membranes) where rods are replaced by slots. Such free...

  13. Optical tests of 200mm MWIR polarizer wafers: methodology and results

    Science.gov (United States)

    Erbach, Peter S.; Pezzaniti, J. Larry; Reinhardt, John C.; Chenault, David B.; Goldstein, Dennis H.

    2012-06-01

    Wiregrid polarizers are commonly employed as optical components in polarization sensitive imaging systems in the infrared waveband. Achieving acceptable performance from wiregrid polarizers typically requires small feature sizes and small periods, large aspect ratios, and subtle control over duty cycle. In many cases, the metrics mentioned above can be realized with manufacturing techniques developed in the semiconductor industry. However, metrology techniques commonly utilized in the semiconductor industry are not necessarily conducive to measuring the effective performance across a large substrate. These techniques typically allow testing or inspection of only very small scale representations of the subwavelength features on the wiregrid polarizers. These techniques - for example the scanning electron micrograph, or SEM - may also damage the wiregrid polarizer. In this paper we present a non-destructive optical imaging method for measuring the performance of the entire infrared wiregrid polarizer produced on a 200mm substrate. This test method allows the users to see large scale errors present during the fabrication process that may not be visible with other metrology techniques. In addition, this technique directly correlates polarizer performance to manufacturing errors.

  14. Models of the Optical/Ultraviolet Continuum Polarization in Active Galactic Nuclei: Implications for Unification Schemes

    Science.gov (United States)

    Kartje, John F.

    1995-10-01

    I have computed the 1200-8000 A thermal continuum polarization induced by gas and dust arranged in configurations compatible with current active galactic nuclei (AGNs) unification schemes. Both uniform- density tori and stratified-density disk-driven winds were considered. A Monte Carlo radiative transfer code was developed which includes the polarization mechanisms of electron and dust scattering as well as dichroic extinction by aligned grains. A Galactic-type grain population was assumed. Based on these calculations, I propose a new interpretation of many of the observed polarization traits of Seyfert galaxies and QSOs: namely, that the polarization in these sources is induced by the same optically thick material which is assumed to obscure the central engine in unification schemes. In particular, I suggest that stratified-density winds could provide a natural explanation (and one consistent with unification models) of the polarization trends observed in Seyfert galaxies. Such winds can display polarizations (P ≲ 20%) oriented perpendicular to the axis along viewing angles inclined to the axis by θ0 ≳ 45° in well-collimated winds, this polarization shifts to smaller magnitudes (P ≲ 2%) and parallel orientations for more face-on viewing, consistent with the patterns observed in Seyfert 2 and Seyfert 1 sources, respectively. In less-collimated winds, scattering alone tends to produce parallel orientations for all viewing angles; perpendicular polarization at large θ0 can result if there is a high degree of magnetic grain alignment. The simplest torus models (i.e., uniform-density, opaque gas and dust) do not reproduce this flip in polarization position angle. Furthermore, they generally display high polarization magnitudes (P ≳ 10%) along most viewing angles θ0 > θ∞ (where θ is the torus half-opening angle) and negligible polarization along θ0 > θ∞. Unlike previous models for AGN polarization which invoke scattering by optically thin electron

  15. Microbend fiber optic sensor for perioperative pediatric vital signs monitoring

    Science.gov (United States)

    Chen, Zhihao; Hee, Hwan Ing; Ng, Soon Huat; Teo, Ju Teng; Yang, Xiufeng; Wang, Dier

    2017-02-01

    We have demonstrated a highly sensitive microbend fiber optic sensor for perioperative pediatric vital signs monitoring that is free from direct contact with skin, cableless, electromagnetic interference free and low cost. The feasibility of our device was studied on infants undergoing surgery and 10 participants ranging from one month to 12 months were enrolled. The sensor was placed under a barrier sheet on the operating table. All patients received standard intraoperative monitoring. The results showed good agreement in heart rate and respiratory rate between our device and the standard physiological monitoring when signals are clean.

  16. Optical Monitoring of Quasars; 1, Variability

    CERN Document Server

    García, A; Jablonski, F J; Terlevich, R J

    1999-01-01

    We present an analysis of quasar variability from data collected during a photometric monitoring of 50 objects carried out at CNPq/Laboratorio Nacional de Astrofisica, Brazil, between March 1993 and July 1996. A distinctive feature of this survey is its photometric accuracy, ~ 0.02 V mag, achieved through differential photometry with CCD detectors, what allows the detection of faint levels of variability. We find that the relative variability, delta = sigma / L, observed in the V band is anti-correlated with both luminosity and redshift, although we have no means of discovering the dominant relation, given the strong coupling between luminosity and redshift for the objects in our sample.We introduce a model for the dependence of quasar variability on frequency that is consistent with multi-wavelength observations of the nuclear variability of the Seyfert galaxy NGC 4151. We show that correcting the observed variability for this effect slightly increases the significance of the trends of variability with lumin...

  17. Fiber-Optic Monitoring System of Particle Counters

    Directory of Open Access Journals (Sweden)

    A. A. Titov

    2016-01-01

    Full Text Available The article considers development of a fiber-optic system to monitor the counters of particles. Presently, optical counters of particles, which are often arranged at considerable distance from each other, are used to study the saltation phenomenon. For monitoring the counters, can be used electric communication lines.However, it complicates and raises the price of system Therefore, we offered a fiber-optic system and the counter of particles, free from these shortcomings. The difference between the offered counter of particles and the known one is that the input of radiation to the counter and the output of radiation scattering on particles are made by the optical fibers, and direct radiation is entered the optical fiber rather than is delayed by a light trap and can be used for lighting the other counters thereby allowing to use their connection in series.The work involved a choice of the quartz multimode optical fiber for communication, defining the optical fiber and lenses parameters of the counter of particles, and a selection of the radiation source and the photo-detector.Using the theory of light diffraction on a particle, a measuring range of the particle sizes has been determined. The system speed has been estimated, and it has been shown that a range of communication can reach 200km.It should be noted that modulation noise of counters of particles connected in series have the impact on the useful signal. To assess the extent of this influence we have developed a calculation procedure to illustrate that with ten counters connected in series this influence on the signal-to-noise ratio will be insignificant.Thus, it has been shown that the offered fiber-optic system can be used for monitoring the counters of particles across the desertified territories. 

  18. Investigations of Polarization Dependent Loss in Polarization Modulated Analog Optical Links

    Science.gov (United States)

    2015-12-29

    to minimize the 2nd harmonic at -16 dBm input RF power after adding PDL (Black). 10      Fig. 4.2: Curves for 4.1 V bias applied after PDL...Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be...nonlinearity. Finally, the polarization modulator nonlinearities are investigated, with the results showing the tradeoffs for using either the DC bias of a

  19. Surface optical phonon-assisted cyclotron resonance in graphene on polar substrates

    Energy Technology Data Exchange (ETDEWEB)

    Phuc, Huynh Vinh, E-mail: hvphuc@dthu.edu.vn [Division of Theoretical Physics, Dong Thap University, Dong Thap 93000 (Viet Nam); Dinh, Le [Center for Theoretical & Computational Physics, College of Education, Hue University, Hue 47000 (Viet Nam)

    2015-08-01

    We theoretically study the influence of surface optical (SO) phonons on the phonon-assisted cyclotron resonance (PACR) effect in a single-layer graphene on different polar substrates via both one- and two-photon absorption processes. The two-photon absorption process gives a significant contribution to magneto-optical absorption coefficient (MOAC) compared to one-photon process. The shifts of the absorption peaks are larger for polar substrates than those in graphene on nonpolar substrates, where only the intrinsic optical phonons of graphene with higher energy contribute. Effects of temperature, graphene-substrate separation, and magnetic field on the magneto-optical absorption coefficient and the half-width are discussed. Our results provide a significantly quantitative picture for SO phonons interaction induced magneto-optical absorption in graphene on polar substrates. - Highlights: • PACR in graphene on polar substrates has been investigated. • The two-photon absorption process has been included. • The combined effect on MOAC and half-width has been discussed. • A significantly quantitative picture for SO phonons interaction has been provided.

  20. Handbook of Coherent-Domain Optical Methods Biomedical Diagnostics, Environmental Monitoring, and Materials Science

    CERN Document Server

    2013-01-01

    This Handbook provides comprehensive coverage of laser and coherent-domain methods as applied to biomedicine, environmental monitoring, and materials science. Worldwide leaders in these fields describe the fundamentals of light interaction with random media and present an overview of basic research. The latest results on coherent and polarization properties of light scattered by random media, including tissues and blood, speckles formation in multiple scattering media, and other non-destructive interactions of coherent light with rough surfaces and tissues, allow the reader to understand the principles and applications of coherent diagnostic techniques. The expanded second edition has been thoroughly updated with particular emphasis on novel coherent-domain techniques and their applications in medicine and environmental science. Volume 1 describes state-of-the-art methods of coherent and polarization optical imaging, tomography and spectroscopy; diffusion wave spectroscopy; elastic, quasi-elastic and inelasti...

  1. Experiment Study of Fiber Optic Sensing in Railway Security Monitoring

    Institute of Scientific and Technical Information of China (English)

    Dian Fan; De-Sheng Jiang; Wei-Lai Li

    2008-01-01

    Aiming at some security problems in railway running and the application condition of existing technology, this paper studies some issues of using fiber optic sensing technology in railway security monitoring. Through field experiment measuring the strain of the rail and analyzing the experiment data, the method of diagnosing the health condition of rail and wheel is investigated.

  2. The relationship between variable and polarized optical spectral components of luminous type 1 non-blazar quasars

    CERN Document Server

    Kokubo, Mitsuru

    2016-01-01

    Optical spectropolarimetry carried out by Kishimoto et al. (2004) has shown that several luminous type 1 quasars show a strong decrease of the polarized continuum flux in the rest-frame near-UV wavelengths of $\\lambda<4000$\\AA. In the literature, this spectral feature is interpreted as evidence of the broadened hydrogen Balmer absorption edge imprinted in the accretion disk thermal emission due to the disk atmospheric opacity effect. On the other hand, the quasar flux variability studies have shown that the variable continuum component in UV-optical spectra of quasars, which is considered to be a good indicator of the intrinsic spectral shape of the accretion disk emission, generally have significantly flat spectral shape throughout the near-UV to optical spectral range. To examine whether the disk continuum spectral shapes revealed as the polarized flux and as the variable component spectra are consistent with each other, we carry out multi-band photometric monitoring observations for a sample of four pol...

  3. Conversion circularly polarized beam shifting optical vortices with a fractional topological charges in a uniaxial crystal

    Science.gov (United States)

    Pogrebnaya, A. O.; Halilov, S. I.; Rubass, A. F.

    2016-08-01

    In this work we have studied the distribution of a circularly polarized beam carrying the optical vortex with fractional topological charge equal to ½ in a uniaxial crystal. We have found that by increasing the angle of inclination of the beam relative to the optical axis of the crystal to α = 1.75 °, mixed dislocation movement observed wave front interference pattern to beam periphery. Experimental research has shown that when the angle α = 2 ° in the central region of the beam, we are seeing the emergence of "fork", optical vortex with a topological charge of the order of 1. The results show depolarization of the beam and the transition to the spin angular momentum of the orbital angular momentum. The intensity of the RCP and LCP component in the beam carrying the optical vortex with fractional topological charge oscillate. The total intensity of the beam as the sum of two orthogonally polarized components does not change.

  4. Damage monitoring and impact detection using optical fiber vibration sensors

    Science.gov (United States)

    Yang, Y. C.; Han, K. S.

    2002-06-01

    Intensity-based optical fiber vibrations sensors (OFVSs) are used in damage monitoring of fiber-reinforced plastics, in vibration sensing, and location of impacts. OFVSs were constructed by placing two cleaved fiber ends in a capillary tube. This sensor is able to monitor structural vibrations. For vibration sensing, the optical fiber sensor was mounted on the carbon fiber reinforced composite beam, and its response was investigated for free and forced vibration. For locating impact points, four OFVSs were placed at chosen positions and the different arrival times of impact-generated vibration signals were recorded. The impact location can be determined from these time delays. Indentation and tensile tests were performed with the measurement of the optical signal and acoustic emission (AE). The OFVSs accurately detected both free and forced vibration signals. Accurate locations of impact were determined on an acrylate plate. It was found that damage information, comparable in quality to AE data, could be obtained from the OFVS signals.

  5. Blind, fast and SOP independent polarization recovery for square dual polarization-MQAM formats and optical coherent receivers.

    Science.gov (United States)

    Chagnon, Mathieu; Osman, Mohamed; Xu, Xian; Zhuge, Qunbi; Plant, David V

    2012-12-03

    We present both theoretically and experimentally a novel blind and fast method for estimating the State of Polarization (SOP) of a single carrier channel modulated in square Dual Polarization (DP) MQAM format for optical coherent receivers. The method can be used on system startup, for quick channel reconfiguration, or for burst mode receivers. It consists of converting the received waveform from Jones to Stokes space and looping over an algorithm until a unitary polarization derotation matrix is estimated. The matrix is then used to initialize the center taps of the subsequent classical decision-directed stochastic gradient algorithm (DD-LMS). We present experimental comparisons of the initial Bit Error Rate (BER) and the speed of convergence of this blind Stokes space polarization recovery (PR) technique against the common Constant Modulus Algorithm (CMA). We demonstrate that this technique works on any square DP-MQAM format by presenting experimental results for DP-4QAM, -16QAM and -64QAM at varying distances and baud rates. We additionally numerically assess the technique for varying differential group delays (DGD) and sampling offsets on 28 Gbaud DP-4QAM format and show fast polarization recovery for instantaneous DGD as high as 90% of symbol duration. We show that the convergence time of this blind PR technique does not depend on the initial SOP as CMA does and allows switching to DD-LMS faster by more than an order of magnitude. For DP-4QAM, it shows a convergence time of 5.9 ns, which is much smaller than the convergence time of recent techniques using modified CMA algorithms for quicker convergence. BER of the first 20 × 10(3) symbols is always smaller by several factors for DP-16QAM and -64QAM but not always for DP-4QAM.

  6. The Variable Polarization XUV Beamline P04 at PETRA III: Optics, mechanics and their performance

    Energy Technology Data Exchange (ETDEWEB)

    Viefhaus, Jens, E-mail: jens.viefhaus@desy.de [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany); Scholz, Frank; Deinert, Sascha; Glaser, Leif; Ilchen, Markus; Seltmann, Jörn; Walter, Peter [Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg (Germany); Siewert, Frank, E-mail: frank.siewert@helmholtz-berlin.de [Helmholtz-Zentrum Berlin (HZB) für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin (Germany)

    2013-05-11

    The layout of the Variable Polarization XUV Beamline P04 at PETRA III is described with emphasis on selected examples of optics, mirrors and gratings. A precise characterization of the optics, their performance inside the holder and of the surrounding mechanics is presented. This also includes a detailed characterization of the different beamline mechanics as a whole (grating unit, exit slit unit, re-focusing unit) including the environment.

  7. Spatial correlations and partial polarization in electromagnetic optical fields : effects of evanescent waves

    OpenAIRE

    Setälä, Tero

    2003-01-01

    In this thesis, partial polarization and spatial correlation properties of electromagnetic optical fields are investigated. The emphasis is on near fields which exist only within the distance of the light wavelength from the emitting or scattering object. In the near-field region, the contribution of the evanescent (non-radiating) waves is overwhelming compared to the propagating waves that can be observed far from the source. Certain fundamental issues related to the optical near-fields ...

  8. Simultaneous polarization monitoring of SN2007uy and the axisymmetric SN2008D/XRF080109: isolating geometry from dust

    CERN Document Server

    Gorosabel, J; Castro-Tirado, A J; Agudo, I; Jelinek, M; Leon, S; Augusteijn, T; Fynbo, J P U; Hjorth, J; Michalowski, M J; Xu, D; Ferrero, P; Kann, D A; Klose, S; Rossi, A; Madrid, J P; LLorente, A; Bremer, M; Winters, J -M

    2008-01-01

    We report the results of an optical linear polarization monitoring carried out simultaneously for SN2007uy and SN2008D. The observations span 74.9 days, starting 3.6 days after the X-ray outburst of SN2008D and are distributed in 11 visits. For both SNe the polarization is dominated by the host galaxy interstellar polarization (HGIP), especially for SN2007uy. This fact is supported by 1.2 millimeter (mm) observations of NGC2770, carried out at and around the SN2008D position. The 1.2 mm data are consistent with no intrinsic emission from SN2008D and can be entirely explained by the NGC2770 dust emission. Comparing spectroscopic extinction values reported in the literature with the extinction derived from the 1.2 mm data, we conclude that the NGC2770 extinction distribution is heterogeneous. We report also a 3.3 mm flux detection at the SN2008D position, possibly due to the intrinsic SN emission, and not due to the dust. Despite the dominant HGIP, a statistical analysis of the distribution of the SN2008D Stoke...

  9. Cryosurgery treatment of actinic keratoses monitored by optical coherence tomography

    DEFF Research Database (Denmark)

    Themstrup, L.; Banzhaf, C.; Jemec, G.B.E.

    2013-01-01

    Background: Optical coherence tomography (OCT) is a non-invasive optical imaging technique providing high-resolution images. OCT may be useful as a monitoring tool during treatment of actinic keratoses (AK) and skin cancer. Objective: To examine and describe how OCT skin morphology changes when...... could not be monitored by OCT. Vesicle formation after cryotherapy could be identified in OCT images. In ex vivo skin no vesicle formation occurred. Conclusion: OCT cannot monitor the freezing depth, but OCT was able to visualise AK lesions and vesicle formation shortly after cryotherapy. Results add...... the tissue is exposed to the effects of cryotherapy. Methods: Normal ex vivo skin and in vivo AK lesions were examined. Cryotherapy was applied and OCT images were acquired at defined time points. OCT morphology was described. Results: Cryotherapy treatment produced an opaque iceball, and freezing depth...

  10. Nonnormal operators in physics, a singular-vectors approach: illustration in polarization optics.

    Science.gov (United States)

    Tudor, Tiberiu

    2016-04-20

    The singular-vectors analysis of a general nonnormal operator defined on a finite-dimensional complex vector space is given in the frame of a pure operatorial ("nonmatrix," "coordinate-free") approach, performed in a Dirac language. The general results are applied in the field of polarization optics, where the nonnormal operators are widespread as operators of various polarization devices. Two nonnormal polarization devices representative for the class of nonnormal and even pathological operators-the standard two-layer elliptical ideal polarizer (singular operator) and the three-layer ambidextrous ideal polarizer (singular and defective operator)-are analyzed in detail. It is pointed out that the unitary polar component of the operator exists and preserves, in such pathological case too, its role of converting the input singular basis of the operator in its output singular basis. It is shown that for any nonnormal ideal polarizer a complementary one exists, so that the tandem of their operators uniquely determines their (common) unitary polar component.

  11. A compendium of AGN inclinations with corresponding UV/optical continuum polarization measurements

    Science.gov (United States)

    Marin, F.

    2014-06-01

    The anisotropic nature of active galactic nuclei (AGN) is thought to be responsible for the observational differences between type-1 (pole-on) and type-2 (edge-on) nearby Seyfert-like galaxies. In this picture, the detection of emission and/or absorption features is directly correlated to the inclination of the system. The AGN structure can be further probed by using the geometry-sensitive technique of polarimetry, yet the pairing between observed polarization and Seyfert type remains poorly examined. Based on archival data, I report here the first compilation of 53 estimated AGN inclinations matched with ultraviolet/optical continuum polarization measurements. Corrections, based on the polarization of broad emission lines, are applied to the sample of Seyfert-2 AGN to remove dilution by starburst light and derive information about the scattered continuum alone. The resulting compendium agrees with past empirical results, i.e. type-1 AGN show low polarization degrees (P ≤ 1 per cent) predominantly associated with a polarization position angle parallel to the projected radio axis of the system, while type-2 objects show stronger polarization percentages (P > 7 per cent) with perpendicular polarization angles. The transition between type-1 and type-2 inclination occurs between 45° and 60° without noticeable impact on P. The compendium is further used as a test to investigate the relevance of four AGN models. While an AGN model with fragmented regions matches observations better than uniform models, a structure with a failed dusty wind along the equator and disc-born, ionized, polar outflows is by far closer to observations. However, although the models correctly reproduce the observed dichotomy between parallel and perpendicular polarization, as well as correct polarization percentages at type-2 inclinations, further work is needed to account for some highly polarized type-1 AGN.

  12. Quantum nonlinear optics with polar J-aggregates in microcavities

    CERN Document Server

    Herrera, Felipe; Pachon, Leonardo A; Saikin, Semion K; Aspuru-Guzik, Alán

    2014-01-01

    We show that an ensemble of organic dye molecules with permanent electric dipole moments embedded in a microcavity can lead to strong optical nonlinearities at the single photon level. The strong long-range electrostatic interaction between chromophores due to their permanent dipoles introduces the desired nonlinearity of the light-matter coupling in the microcavity. We obtain the absorption spectra of a weak probe field under the influence of strong exciton-photon coupling with the cavity field. Using realistic parameters, we demonstrate that a single cavity photon can significantly modify the absorptive and dispersive response of the medium to a probe photon at a different frequency. Finally, we show that the system is in the regime of cavity-induced transparency with a broad transparency window for dye dimers. We illustrate our findings using pseudoisocyanine chloride (PIC) J-aggregates in currently-available optical microcavities.

  13. Continuous monitoring of arthritis in animal models using optical imaging modalities

    Science.gov (United States)

    Son, Taeyoon; Yoon, Hyung-Ju; Lee, Saseong; Jang, Won Seuk; Jung, Byungjo; Kim, Wan-Uk

    2014-10-01

    Given the several difficulties associated with histology, including difficulty in continuous monitoring, this study aimed to investigate the feasibility of optical imaging modalities-cross-polarization color (CPC) imaging, erythema index (EI) imaging, and laser speckle contrast (LSC) imaging-for continuous evaluation and monitoring of arthritis in animal models. C57BL/6 mice, used for the evaluation of arthritis, were divided into three groups: arthritic mice group (AMG), positive control mice group (PCMG), and negative control mice group (NCMG). Complete Freund's adjuvant, mineral oil, and saline were injected into the footpad for AMG, PCMG, and NCMG, respectively. LSC and CPC images were acquired from 0 through 144 h after injection for all groups. EI images were calculated from CPC images. Variations in feet area, EI, and speckle index for each mice group over time were calculated for quantitative evaluation of arthritis. Histological examinations were performed, and the results were found to be consistent with those from optical imaging analysis. Thus, optical imaging modalities may be successfully applied for continuous evaluation and monitoring of arthritis in animal models.

  14. Monitoring of the Lac Bam Wetland Extent Using Dual-Polarized X-Band SAR Data

    Directory of Open Access Journals (Sweden)

    Linda Moser

    2016-04-01

    Full Text Available Wetlands in semi-arid Africa are vital as water resource for local inhabitants and for biodiversity, but they are prone to strong seasonal fluctuations. Lac Bam is the largest natural freshwater lake in Burkina Faso, its water is mixed with patches of floating or flooded vegetation, and very turbid and sediment-rich. These characteristics as well as the usual cloud cover during the rainy season can limit the suitability of optical remote sensing data for monitoring purposes. This study demonstrates the applicability of weather-independent dual-polarimetric Synthetic Aperture Radar (SAR data for the analysis of spatio-temporal wetland dynamics. A TerraSAR-X repeat-pass time series of dual-co-polarized HH-VV StripMap data—with intervals of 11 days, covering two years (2013–2015 from the rainy to the dry season—was processed to normalized Kennaugh elements and classified mono-temporally and multi-temporally. Land cover time series and seasonal duration maps were generated for the following four classes: open water, flooded/floating vegetation, irrigated cultivation, and land (non-wetland. The added value of dual-polarimetric SAR data is demonstrated by significantly higher multitemporal classification accuracies, where the overall accuracy (88.5% exceeds the classification accuracy using single-polarimetric SAR intensity data (82.2%. For relevant change classes involving flooded vegetation and irrigated fields dual-polarimetric data (accuracies: 75%–97% are favored to single-polarimetric data (42%–87%. This study contributes to a better understanding of the dynamics of semi-arid African wetlands in terms of water areas including water with flooded vegetation, and the location and timing of irrigated cultivations.

  15. Online monitoring of chemical reactions by polarization-induced electrospray ionization.

    Science.gov (United States)

    Meher, Anil Kumar; Chen, Yu-Chie

    2016-09-21

    Polarization-induced electrospray ionization (PI-ESI) is a simple technique for instant generation of gas-phase ions directly from a microliter-sized droplet for mass spectrometric analysis. A sample droplet was placed over a dielectric substrate and in proximity (2-3 mm) to the inlet of a mass spectrometer. Owing to the polarization effect induced by the high electric field provided by the mass spectrometer, the droplet was polarized and the electrospray was generated from the apex of the droplet. The polarization-induced electrospray could last for tens of seconds, which was sufficiently long to monitor fast reactions occurring within few seconds. Thus, we demonstrated the feasibility of using the droplet-based PI-ESI MS for the online monitoring of fast reactions by simply mixing two droplets (5-10 μL) containing reactants on a dielectric substrate placed in front of a mass spectrometer applied with a high voltage (-4500 V). Schiff base reactions and oxidation reactions that can generate intermediates/products within a few seconds were selected as the model reactions. The ionic reaction species generated from intermediates and products can be simultaneously monitored by PI-ESI MS in real time. We also used this approach to selectively detect acetone from a urine sample, in which acetone was derivatized in situ. In addition, the possibility of using this approach for quantitative analysis of acetone from urine samples was examined.

  16. Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

    Science.gov (United States)

    Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

    2016-02-01

    Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has the potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen-vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarization. We illustrate numerically the effectiveness of the model in a flow cell containing nanodiamonds immobilized in a hydrogel, polarizing flowing water molecules 4700-fold above thermal polarization in a magnetic field of 0.35 T, in volumes detectable by current NMR scanners.

  17. Early-time polarized optical light curve of GRB 131030A

    CERN Document Server

    King, O G; Giannios, D; Papadakis, I; Angelakis, E; Balokovic, M; Fuhrmann, L; Hovatta, T; Khodade, P; Kiehlmann, S; Kylafis, N; Kus, A; Myserlis, I; Modi, D; Panopoulou, G; Papamastorakis, I; Pavlidou, V; Pazderska, B; Pazderski, E; Pearson, T J; Rajarshi, C; Ramaprakash, A N; Readhead, A C S; Reig, P; Tassis, K; Zensus, J A

    2014-01-01

    We report the polarized optical light curve of a gamma-ray burst afterglow obtained using the RoboPol instrument. Observations began 655 seconds after the initial burst of gamma-rays from GRB131030A, and continued uninterrupted for 2 hours. The afterglow displayed a low, constant fractional linear polarization of $p = (2.1 \\pm 1.6)\\,\\%$ throughout, which is similar to the interstellar polarization measured on nearby stars. The optical brightness decay is consistent with a forward-shock propagating in a medium of constant density, and the low polarization fraction indicates a disordered magnetic field in the shock front. This supports the idea that the magnetic field is amplified by plasma instabilities on the shock front. These plasma instabilities produce strong magnetic fields with random directions on scales much smaller than the total observable region of the shock, and the resulting randomly-oriented polarization vectors sum to produce a low net polarization over the total observable region of the shock.

  18. Polarization-insensitive optical gain characteristics of highly stacked InAs/GaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Takashi; Suwa, Masaya; Kaizu, Toshiyuki; Harada, Yukihiro [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan)

    2014-06-21

    The polarized optical gain characteristics of highly stacked InAs/GaAs quantum dots (QDs) with a thin spacer layer fabricated on an n{sup +}-GaAs (001) substrate were studied in the sub-threshold gain region. Using a 4.0-nm-thick spacer layer, we realized an electronically coupled QD superlattice structure along the stacking direction, which enabled the enhancement of the optical gain of the [001] transverse-magnetic (TM) polarization component. We systematically studied the polarized electroluminescence properties of laser devices containing 30 and 40 stacked InAs/GaAs QDs. The net modal gain was analyzed using the Hakki-Paoli method. Owing to the in-plane shape anisotropy of QDs, the polarization sensitivity of the gain depends on the waveguide direction. The gain showing polarization isotropy between the TM and transverse-electric polarization components is high for the [110] waveguide structure, which occurs for higher amounts of stacked QDs. Conversely, the isotropy of the [−110] waveguide is easily achieved even if the stacking is relatively low, although the gain is small.

  19. High-order polarization mode crosstalk effect: a calibration scheme of white light-based optical coherence domain polarimetry

    Science.gov (United States)

    Wu, Bing; Yang, Jun; Zhang, Jianzhong; Liang, Shuai; Yu, Zhangjun; Yuan, Yonggui; Peng, Feng; Zhou, Ai; Zhang, Yu; Yuan, Libo

    2015-09-01

    We propose a calibration scheme of the white light interferometer based optical coherence domain polarimetry (OCDP), which could be used to measure the ultra-weak polarization mode crosstalk (PMC) or the ultra-high polarization extinction ratio (PER) of different polarization optical devices. The calibration depends on the first and second order PMC effect of different polarization devices in series. The first and second PMCs between 0 and -90dB, established by five pieces of polarization maintaining fiber (PMF) and a Y-waveguide, is used to prove its feasibility.

  20. Color controllable polarization entanglement generation in optical fiber at telecommunication wavelengths.

    Science.gov (United States)

    Karmakar, Sanjit; Meyers, Ronald E

    2015-08-10

    This article proposes a polarized entangled photon source in optical fiber with low Raman noise that features the controllable generation of specific signal and idler wavelengths (colors) by varying the pump power. The novel two color source can provide needed telecom entangled photon wavelengths for applications in quantum communications, quantum computing, and quantum imaging.

  1. A telecom-wavelength atomic quantum memory in optical fiber for heralded polarization qubits

    CERN Document Server

    Jin, Jeongwan; Puigibert, Marcel li Grimau; Verma, Varun B; Marsili, Francesco; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

    2015-01-01

    Photon-based quantum information processing promises new technologies including optical quantum computing, quantum cryptography, and distributed quantum networks. Polarization-encoded photons at telecommunication wavelengths provide a compelling platform for practical realization of these technologies. However, despite important success towards building elementary components compatible with this platform, including sources of entangled photons, efficient single photon detectors, and on-chip quantum circuits, a missing element has been atomic quantum memory that directly allows for reversible mapping of quantum states encoded in the polarization degree of a telecom-wavelength photon. Here we demonstrate the quantum storage and retrieval of polarization states of heralded single-photons at telecom-wavelength by implementing the atomic frequency comb protocol in an ensemble of erbium atoms doped into an optical fiber. Despite remaining limitations in our proof-of-principle demonstration such as small storage eff...

  2. Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

    CERN Document Server

    Chen, Qiong; Jelezko, Fedor; Retzker, Alex; Plenio, Martin B

    2015-01-01

    Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarisation. We illustrate numerically the effectiveness of the model in a flow cel...

  3. Coherent polarization locking: an approach to mitigating optical damage in a pulsed Ho:YAG laser.

    Science.gov (United States)

    Tan, L H; Chua, C F; Phua, P B

    2013-04-01

    Intracavity optical damage is mitigated in a pulsed Ho:YAG laser cavity using the coherent polarization locking (CPL) technique. By splitting the available pump power into two individual Ho:YAG laser rods, we passively coherently locked two orthogonal polarization lasers with 9.13 mJ output pulse energies and 14 ns pulsewidths, and operating at 800 Hz repetition rate. A conventional Ho:YAG laser cavity with the same pump and cavity configuration results in severe optical damage when operating at <2 kHz repetition rate, thus limiting the output pulse energies to <5 mJ. We also demonstrated, to the best of our knowledge, the first pulsed operation within the entire CPL Ho:YAG laser cavity by Q-switching in one of the polarization arms, producing nanosecond pulses with no sign of pulse instability.

  4. Continuous rotation of a cholesteric liquid crystalline droplet by a circularly polarized optical tweezers

    Science.gov (United States)

    Tamura, Yuta; Kimura, Yasuyuki

    2017-04-01

    We studied the opto-mechanical response of droplets composed of cholesteric liquid crystal (ChLC) to a circularly polarized optical tweezers. Although the alignment of LC molecular within a droplet depends on the relative ratio of the droplet diameter d to the helical pitch p, the optically induced rotation was found to be asymmetric to the direction of circularly polarized light irrespective to the inner molecular alignment. We studied the rotation of the droplets with various sizes, helical pitch (strength of chirality) and different chirality. In the case of d/p 1, the direction of the rotation was simply determined by chirality of ChLC and the rotation was also observed for linearly polarized light, which has already been reported by Yang et al.

  5. Applicability of polar organic compound integrative samplers for monitoring pesticides in groundwater.

    Science.gov (United States)

    Berho, Catherine; Togola, Anne; Coureau, Charlotte; Ghestem, Jean-Philippe; Amalric, Laurence

    2013-08-01

    Polar organic chemical integrative samplers (POCISs) for the monitoring of polar pesticides in groundwater were tested on two sites in order to evaluate their applicability by comparison with the spot-sampling approach. This preliminary study shows that, as in surface water, POCIS is a useful tool, especially for the screening of substances at low concentration levels that are not detected by laboratory analysis of spot samples. For quantitative results, a rough estimation is obtained. The challenge is now to define the required water-flow conditions for a relevant quantification of pesticides in groundwater and to establish more representative sampling rates for groundwater.

  6. Modeling optical and UV polarization of AGNs. III. From uniform-density to clumpy regions

    Science.gov (United States)

    Marin, F.; Goosmann, R. W.; Gaskell, C. M.

    2015-05-01

    Context. A growing body of evidence suggests that some, if not all, scattering regions of active galactic nuclei (AGNs) are clumpy. The inner AGN components cannot be spatially resolved with current instruments and must be studied by numerical simulations of observed spectroscopy and polarization data. Aims: We run radiative transfer models in the optical/UV for a variety of AGN reprocessing regions with different distributions of clumpy scattering media. We obtain geometry-sensitive polarization spectra and images to improve our previous AGN models and their comparison with the observations. Methods: We use the latest public version 1.2 of the Monte Carlo code stokes presented in the first two papers of this series to model AGN reprocessing regions of increasing morphological complexity. We replace previously uniform-density media with up to thousands of constant-density clumps. We couple a continuum source to fragmented equatorial scattering regions, polar outflows, and toroidal obscuring dust regions and investigate a wide range of geometries. We also consider different levels of fragmentation in each scattering region to evaluate the importance of fragmentation for the net polarization of the AGN. Results: In comparison with uniform-density models, equatorial distributions of gas and dust clouds result in grayer spectra and show a decrease in the net polarization percentage at all lines of sight. The resulting polarization position angle depends on the morphology of the clumpy structure, with extended tori favoring parallel polarization while compact tori produce orthogonal polarization position angles. In the case of polar scattering regions, fragmentation increases the net polarization unless the cloud filling factor is small. A complete AGN model constructed from the individual, fragmented regions can produce low polarization percentages (<2%), with a parallel polarization angle for observer inclinations up to 70° for a torus half opening angle of 60°. For

  7. Optical modeling and polarization calibration for CMB measurements with ACTPol and Advanced ACTPol

    Science.gov (United States)

    Koopman, Brian; Austermann, Jason; Cho, Hsiao-Mei; Coughlin, Kevin P.; Duff, Shannon M.; Gallardo, Patricio A.; Hasselfield, Matthew; Henderson, Shawn W.; Ho, Shuay-Pwu Patty; Hubmayr, Johannes; Irwin, Kent D.; Li, Dale; McMahon, Jeff; Nati, Federico; Niemack, Michael D.; Newburgh, Laura; Page, Lyman A.; Salatino, Maria; Schillaci, Alessandro; Schmitt, Benjamin L.; Simon, Sara M.; Vavagiakis, Eve M.; Ward, Jonathan T.; Wollack, Edward J.

    2016-07-01

    The Atacama Cosmology Telescope Polarimeter (ACTPol) is a polarization sensitive upgrade to the Atacama Cosmology Telescope, located at an elevation of 5190 m on Cerro Toco in Chile. ACTPol uses transition edge sensor bolometers coupled to orthomode transducers to measure both the temperature and polarization of the Cosmic Microwave Background (CMB). Calibration of the detector angles is a critical step in producing polarization maps of the CMB. Polarization angle offsets in the detector calibration can cause leakage in polarization from E to B modes and induce a spurious signal in the EB and TB cross correlations, which eliminates our ability to measure potential cosmological sources of EB and TB signals, such as cosmic birefringence. We calibrate the ACTPol detector angles by ray tracing the designed detector angle through the entire optical chain to determine the projection of each detector angle on the sky. The distribution of calibrated detector polarization angles are consistent with a global offset angle from zero when compared to the EB-nulling offset angle, the angle required to null the EB cross-correlation power spectrum. We present the optical modeling process. The detector angles can be cross checked through observations of known polarized sources, whether this be a galactic source or a laboratory reference standard. To cross check the ACTPol detector angles, we use a thin film polarization grid placed in front of the receiver of the telescope, between the receiver and the secondary reflector. Making use of a rapidly rotating half-wave plate (HWP) mount we spin the polarizing grid at a constant speed, polarizing and rotating the incoming atmospheric signal. The resulting sinusoidal signal is used to determine the detector angles. The optical modeling calibration was shown to be consistent with a global offset angle of zero when compared to EB nulling in the first ACTPol results and will continue to be a part of our calibration implementation. The first

  8. Synchronous Optical and Radio Polarization Variability in the Blazar OJ287

    Science.gov (United States)

    D'arcangelo, Francesca D.; Marscher, Alan P.; Jorstad, Svetlana G.; Smith, Paul S.; Larionov, Valeri M.; Hagen-Thorn, Vladimir A.; Williams, G. Grant; Gear, Walter K.; Clemens, Dan P.; Sarcia, Domenic; Grabau, Alex; Tollestrup, Eric V.; Buie, Marc W.; Taylor, Brian; Dunham, Edward

    2009-06-01

    We explore the variability and cross-frequency correlation of the flux density and polarization of the blazar OJ287, using imaging at 43 GHz with the Very Long Baseline Array, as well as optical and near-infrared (near-IR) polarimetry. The polarization and flux density in both the optical waveband and the 43 GHz compact core increased by a small amount in late 2005, and increased significantly along with the near-IR polarization and flux density over the course of 10 days in early 2006. Furthermore, the values of the electric vector position angle (EVPA) at the three wavebands are similar. At 43 GHz, the EVPA of the blazar core is perpendicular to the flow of the jet, while the EVPAs of emerging superluminal knots are aligned parallel to the jet axis. The core polarization is that expected if shear aligns the magnetic field at the boundary between flows of disparate velocities within the jet. Using variations in flux density, percentage polarization, and EVPA, we model the inner jet as a spine-sheath system. The model jet contains a turbulent spine of half-width 1fdg2 and maximum Lorentz factor of 16.5, a turbulent sheath with Lorentz factor of 5, and a boundary region of sheared field between the spine and sheath. Transverse shocks propagating along the fast, turbulent spine can explain the superluminal knots. The observed flux density and polarization variations are then compatible with changes in the direction of the inner jet caused by a temporary change in the position of the core if the spine contains wiggles owing to an instability. In addition, we can explain a stable offset of optical and near-IR percentage polarization by a steepening of spectral index with frequency, as supported by the data.

  9. Electronic polarization-division demultiplexing based on digital signal processing in intensity-modulation direct-detection optical communication systems.

    Science.gov (United States)

    Kikuchi, Kazuro

    2014-01-27

    We propose a novel configuration of optical receivers for intensity-modulation direct-detection (IM · DD) systems, which can cope with dual-polarization (DP) optical signals electrically. Using a Stokes analyzer and a newly-developed digital signal-processing (DSP) algorithm, we can achieve polarization tracking and demultiplexing in the digital domain after direct detection. Simulation results show that the power penalty stemming from digital polarization manipulations is negligibly small.

  10. Acoustic emission monitoring using a multimode optical fiber sensor

    Science.gov (United States)

    Vandenplas, Steve; Papy, Jean-Michel; Wevers, Martine; Van Huffel, Sabine

    2004-07-01

    Permanent damage in various materials and constructions often causes high-energy high-frequency acoustic waves. To detect those so called `acoustic emission (AE) events', in most cases ultrasonic transducers are embedded in the structure or attached to its surface. However, for many applications where event localization is less important, an embedded low-cost multimode optical fiber sensor configured for event counting may be a better alternative due to its corrosion resistance, immunity to electromagnetic interference and light-weight. The sensing part of this intensity-modulated sensor consists of a multimode optical fiber. The sensing principle now relies on refractive index variations, microbending and mode-mode interferences by the action of the acoustic pressure wave. A photodiode is used to monitor the intensity of the optical signal and transient signal detection techniques (filtering, frame-to-frame analysis, recursive noise estimation, power detector estimator) on the photodiode output are applied to detect the events. In this work, the acoustic emission monitoring capabilities of the multimode optical fiber sensor are demonstrated with the fiber sensor embedded in the liner of a Power Data Transmission (PDT) coil to detect damage (delamination, matrix cracking and fiber breaking) while bending the coil. With the Hankel Total Least Square (HTLS) technique, it is shown that both the acoustic emission signal and optical signal can be modeled with a sum of exponentially damped complex sinusoids with common poles.

  11. A Dual Polarized Quasi-Optical SIS Mixer at 550-GHz

    Science.gov (United States)

    Chattopadhyay, Goutam; Miller, David; LeDuc, Henry G.; Zmuidzinas, Jonas

    2000-01-01

    We describe the design, fabrication, and the performance of a low-noise dual-polarized quasi-optical superconductor insulator superconductor (SIS) mixer at 550 GHz. The mixer utilizes a novel cross-slot antenna on a hyperhemispherical substrate lens, two junction tuning circuits, niobium trilayer junctions, and an IF circuit containing a lumped element 180 deg hybrid. The antenna consists of an orthogonal pair of twin-slot antennas, and has four feed points, two for each polarization. Each feed point is coupled to a two-junction SIS mixer. The 180 deg IF hybrid is implemented using a lumped element/microstrip circuit located inside the mixer block. Fourier transform spectrometer (FTS) measurements of the mixer frequency response show good agreement with computer simulations. The measured co-polarized and cross-polarized patterns for both polarizations also agree with the theoretical predictions. The noise performance of the dual-polarized mixer is excellent, giving uncorrected receiver noise temperature of better than 115 K (DSB) at 528 GHz for both the polarizations.

  12. Optical spin polarization and Hanle effect in GaAsSb: Temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Weiyang; Wang, Xingjun, E-mail: xjwang@mail.sitp.ac.cn, E-mail: luwei@mail.sitp.ac.cn; Chen, Pingping; Li, Ning; Lu, Wei, E-mail: xjwang@mail.sitp.ac.cn, E-mail: luwei@mail.sitp.ac.cn [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2014-08-25

    Continuous-wave optical orientation spectroscopy and the Hanle effect are used to investigate the optical spin polarization and spin dephasing time (gT{sub s}) in GaAsSb with a Sb concentration of ∼6% as a function of temperature. Optical and spin polarizations up to ∼21% were achieved at ∼120 K, and the scaled spin lifetime gT{sub s} decreased monotonously from ∼1.5 ns at 5 K to ∼20 ps at 200 K. We demonstrate that the spin properties of GaAs could be modified by incorporating a small percentage of Sb into it, as a result of an increase in the spin–orbit interactions.

  13. Enhancement of third-order nonlinear optical susceptibility of Alqsub>3sub> in polar aprotic solvents.

    Science.gov (United States)

    Derkowska-Zielinska, Beata

    2017-02-01

    The influence of solvent polarity on nonlinear optical properties of tris-(8-hydroxyquinoline)-aluminum (Alqsub>3sub>) was investigated by the degenerate four-wave mixing method at the 532 nm. It was obtained that the effective values of the third-order nonlinear optical susceptibility (χeff⟨3⟩) and the second-order hyperpolarizability (γsub>effsub>) of Alqsub>3sub> depend on the solvent polarity. Additionally, it was found that Alqsub>3sub> dissolved in dimethyl sulfoxide has the highest values of χeff⟨3⟩ and γsub>effsub>. Furthermore, two Stegeman's figures of merit were also calculated. The obtained results suggest that Alqsub>3sub> is also promising material for application in all-optical signal processing devices.

  14. Circularly polarized few-cycle optical rogue waves: rotating reduced Maxwell-Bloch equations.

    Science.gov (United States)

    Xu, Shuwei; Porsezian, K; He, Jingsong; Cheng, Yi

    2013-12-01

    The rotating reduced Maxwell-Bloch (RMB) equations, which describe the propagation of few-cycle optical pulses in a transparent media with two isotropic polarized electronic field components, are derived from a system of complete Maxwell-Bloch equations without using the slowly varying envelope approximations. Two hierarchies of the obtained rational solutions, including rogue waves, which are also called few-cycle optical rogue waves, of the rotating RMB equations are constructed explicitly through degenerate Darboux transformation. In addition to the above, the dynamical evolution of the first-, second-, and third-order few-cycle optical rogue waves are constructed with different patterns. For an electric field E in the three lower-order rogue waves, we find that rogue waves correspond to localized large amplitude oscillations of the polarized electric fields. Further a complementary relationship of two electric field components of rogue waves is discussed in terms of analytical formulas as well as numerical figures.

  15. Optical monitoring the degradation of PLGA inverse opal film

    Institute of Scientific and Technical Information of China (English)

    Li-Guo Sun; Zhuo-Ying Xie; Yuan-Jin Zhao; Hong-Mei Wei; Zhong-Ze Gu

    2013-01-01

    Implantable materials have broad applications in tissue engineering and in vivo sensors.It is essential to know the detailed information of the implantable materials during their degradation.In this paper,we developed a method to monitor the degradation process of a well-used biomaterial,poly(lactide-coglycolide) (PLGA) by taking advantage of inverse opal structure.We found that mass loss,molecular weight and glass transition temperature of PLGA during the degradation process in Hank's artificial body fluid can be in situ monitored by measuring the optical properties of PLGA inverse opal.

  16. Internet optical infrastructure issues on monitoring and failure restoration

    CERN Document Server

    Tapolcai, János; Babarczi, Péter; Rónyai, Lajos

    2015-01-01

    This book covers the issues of monitoring, failure localization, and restoration in the Internet optical backbone, and focuses on the progress of state-of-the-art in both industry standard and academic research. The authors summarize, categorize, and analyze the developed technology in the context of Internet fault management and failure recovery under the Generalized Multi-Protocol Label Switching (GMPLS), via both aspects of network operations and theories. Examines monitoring, failure localization, and failure restoration in the Internet backbone Includes problem formulations based on combinatorial group testing and topology coding Covers state-of-the-art development for the Internet backbone fault management and failure recovery

  17. Optical fibre grating refractometers for resin cure monitoring

    Science.gov (United States)

    Buggy, S. J.; Chehura, E.; James, S. W.; Tatam, R. P.

    2007-06-01

    The use of fibre grating refractometers as a means of monitoring the cure of a UV-cured epoxy resin is presented. The wavelength shift of the attenuation bands of a long period grating and the spectral response of a tilted fibre Bragg grating sensor were measured simultaneously during the cure of the resin and compared with measurements made using a fibre optic Fresnel-based refractometer. The results showed a good correlation (6 × 10-3 rius) and illustrate the potential of the techniques for non-invasive composite material cure monitoring.

  18. Fiber-optic system for monitoring fast photoactivation dynamics of optical highlighter fluorescent proteins.

    Science.gov (United States)

    Pei, Zhiguo; Qin, Lingsong; Zhang, Zhihong; Zeng, Shaoqun; Huang, Zhen-Li

    2011-08-01

    Characterizing the photoactivation performance of optical highlighter fluorescent proteins is crucial to the realization of photoactivation localization microscopy. In contrast to those fluorescence-based approaches that require complex data processing and calibration procedures, here we report a simple and quantitative alternative, which relies on the measurement of small absorption spectra changes over time with a fiber-optic system. Using Dronpa as a representative highlighter protein, we have investigated the capacity of this system in monitoring the fast photoactivation process.

  19. Satellite data acquisition requirements for monitoring of permafrost in polar regions

    Science.gov (United States)

    Bartsch, Annett

    2015-04-01

    Requirements for space based monitoring of permafrost features had been already defined within the IGOS Cryosphere Theme Report at the start of the IPY in 2007 (IGOS, 2007). In 2012 the Polar Space Task Group (PSTG, http://www.wmo.int/pages/prog/sat/pstg_en.php) has been established as the coordinating body of space agencies, in particular the Space Task Group (STG), for space -based observations of Polar Regions after the International Polar Year (IPY) and under the auspices of the World Meteorological Organization's (WMO) Executive Council Panel of Experts on Polar Observations Research and Services (EC-PORS). The PSTG identified the need to review the requirements for permafrost monitoring and to update these requirements as necessary in 2013. Relevant surveys with focus on satellite data are already available from the ESA DUE Permafrost User requirements survey (2009), the United States National Research Council (2014) and the ESA - CliC - IPA - GTN -P workshop in February 2014. These reports have been reviewed and specific needs discussed within the community. Acquisition requirements for monitoring of especially terrain changes (incl. rock glaciers and coastal erosion) and lakes (extent, ice properties etc.) with respect to current satellite missions have been specified. Of special interest for these applications are SAR missions. Current acquisition strategies for space borne SAR data only partially cover polar permafrost regions and some of the longterm in-situ measurement sites. Many stations are located in the proximity to coastal areas and glaciers which to some extent may allow joint usage by different cryosphere applications but requirements may deviate. The results of the discussion are presented in this paper.

  20. Optical Fiber Sensors for Aircraft Structural Health Monitoring

    Directory of Open Access Journals (Sweden)

    Iker García

    2015-06-01

    Full Text Available Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber sensors applied to the monitoring of aircraft structures provide some advantages over traditional sensors. Several practical applications for structures and engines we have been working on are reported in this article. Fiber Bragg gratings have been analyzed in detail, because they have proved to constitute the most promising technology in this field, and two different alternatives for strain measurements are also described. With regard to engine condition evaluation, we present some results obtained with a reflected intensity-modulated optical fiber sensor for tip clearance and tip timing measurements in a turbine assembled in a wind tunnel.

  1. Optical Fiber Sensors for Aircraft Structural Health Monitoring.

    Science.gov (United States)

    García, Iker; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon; Illarramendi, María Asunción; Villatoro, Joel

    2015-06-30

    Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber sensors applied to the monitoring of aircraft structures provide some advantages over traditional sensors. Several practical applications for structures and engines we have been working on are reported in this article. Fiber Bragg gratings have been analyzed in detail, because they have proved to constitute the most promising technology in this field, and two different alternatives for strain measurements are also described. With regard to engine condition evaluation, we present some results obtained with a reflected intensity-modulated optical fiber sensor for tip clearance and tip timing measurements in a turbine assembled in a wind tunnel.

  2. Fiber Optic Sensors for Structural Health Monitoring of Air Platforms

    Directory of Open Access Journals (Sweden)

    Jianping Yao

    2011-03-01

    Full Text Available Aircraft operators are faced with increasing requirements to extend the service life of air platforms beyond their designed life cycles, resulting in heavy maintenance and inspection burdens as well as economic pressure. Structural health monitoring (SHM based on advanced sensor technology is potentially a cost-effective approach to meet operational requirements, and to reduce maintenance costs. Fiber optic sensor technology is being developed to provide existing and future aircrafts with SHM capability due to its unique superior characteristics. This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies. In particular, fiber Bragg grating (FBG sensor technology is evaluated as the most promising tool for load monitoring and damage detection, the two critical SHM aspects of air platforms. At last, recommendations on the implementation and integration of FBG sensors into an SHM system are provided.

  3. Optical Spectrophotometric Monitoring of Fermi/LAT Bright Sources

    CERN Document Server

    Patiño-Álvarez, V; León-Tavares, J; Valdés, J R; Carramiñana, A; Carrasco, L; Torrealba, J

    2013-01-01

    We describe an ongoing optical spectrophotometric monitoring program of a sample of Fermi/LAT bright sources showing prominent and variable {\\gamma}-ray emission, with the 2.1m telescope at Observatorio Astrof\\'isico Guillermo Haro (OAGH) located in Cananea, Sonora, M\\'exico. Our sample contains 11 flat spectrum radio quasars (FSRQ) and 1 Narrow Line Seyfert 1 (NLSy1) galaxy. Our spectroscopic campaign will allow us to study the spectroscopic properties (FWHM, EW, flux) of broad-emission lines in the optical (e.g. H{\\beta}) and mid-UV (e.g. Mg II {\\lambda}2800) regimes, depending on the redshift of the source. The cadence of the broad emission lines monitoring is about five nights per month which in turn will permit us to explore whether there is a correlated variability between broad emission line features and high levels of {\\gamma}-ray emission.

  4. Traffic Monitoring without single Car Detection from optical airborne Images

    OpenAIRE

    Zeller, Klaus; Hinz, Stefan; Rosenbaum, Dominik; Leitloff, Jens; Reinartz, Peter

    2009-01-01

    This article describes several methods for traffic monitoring from airborne optical remote sensing data. These methods classify the traffic into free flowing traffic, traffic congestion and traffic jam. Furthermore a method is explained, which provides information about the average speed of dense traffic on a defined part of the road. All methods gather the information directly from image features, without the use of single vehicle detection. The classification of the traffic is done by st...

  5. Brillouin optical time-domain analysis for geotechnical monitoring

    Institute of Scientific and Technical Information of China (English)

    L. Zeni; L. Picarelli; B. Avolio; A. Coscetta; R. Papa; G. Zeni; C. Di Maio; R. Vassallo; A. Minardo

    2015-01-01

    In this paper, we show some recent experimental applications of Brillouin optical time-domain analysis (BOTDA) based sensors for geotechnical monitoring. In particular, how these sensors can be applied to detecting early movements of soil slopes by the direct embedding of suitable fiber cables in the ground is presented. Furthermore, the same technology can be used to realize innovative inclinometers, as well as smart foundation anchors.

  6. Evidence of Two-Component Optical Polarization in Blazar 1ES 1959+650

    Science.gov (United States)

    Sorcia, Marco; Benítez, Erika; Hiriart, David

    2013-12-01

    In this work we present an analysis of the optical polarimetric variability of the TeV-blazar 1 ES 1959+650 from 2007 October 18 to 2011 May 5. The source showed a maximum variation of 1.2 mag in R- band, and a maximum polarization degree of 12.2%. The blazar presented a preferential position angle of the optical polarization of ~ 153°, with variations of 10° - 50°, which is in agreement with the projected position angle of the parsec-scale jet found at 43 GHz. We infer the existence of the two optically thin synchrotron components that contribute to the polarized flux, consistent with the spine-sheath model. One of them is stable with a constant polarization degree of 4%. Assuming a stationary shock, we estimated some parameters associated with the physics of the relativistic jet: the Doppler factor of δD ˜ 23, the viewing angle of the jet of Φ ~ 2°.4, and the size of the emission region of rb ~ 5.6 × 1017 cm.

  7. Telecom-Wavelength Atomic Quantum Memory in Optical Fiber for Heralded Polarization Qubits

    Science.gov (United States)

    Jin, Jeongwan; Saglamyurek, Erhan; Puigibert, Marcel. lí Grimau; Verma, Varun; Marsili, Francesco; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

    2015-10-01

    Polarization-encoded photons at telecommunication wavelengths provide a compelling platform for practical realizations of photonic quantum information technologies due to the ease of performing single qubit manipulations, the availability of polarization-entangled photon-pair sources, and the possibility of leveraging existing fiber-optic links for distributing qubits over long distances. An optical quantum memory compatible with this platform could serve as a building block for these technologies. Here we present the first experimental demonstration of an atomic quantum memory that directly allows for reversible mapping of quantum states encoded in the polarization degree of freedom of a telecom-wavelength photon. We show that heralded polarization qubits at a telecom wavelength are stored and retrieved with near-unity fidelity by implementing the atomic frequency comb protocol in an ensemble of erbium atoms doped into an optical fiber. Despite remaining limitations in our proof-of-principle demonstration such as small storage efficiency and storage time, our broadband light-matter interface reveals the potential for use in future quantum information processing.

  8. POLARIZATION EVOLUTION OF EARLY OPTICAL AFTERGLOWS OF GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Mi-Xiang; Dai, Zi-Gao [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, Xue-Feng, E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-01-10

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on the polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock requires that the magnetization degree of the jet should not be high (σ ≤ 1), so that the jet is mainly composed of baryons and leptons. We then calculate the light curves and polarization evolution of early optical afterglows and find that when the polarization position angle changes by 90° during the early afterglow, the polarization degree is zero for a toroidal magnetic field but is very likely to be nonzero for an aligned magnetic field. This result would be expected to provide a probe for the central engine of GRBs because an aligned field configuration could originate from a magnetar central engine and a toroidal field configuration could be produced from a black hole via the Blandford–Znajek mechanism. Finally, for such two kinds of magnetic field configurations, we fit the observed data of the early optical afterglow of GRB 120308A equally well.

  9. Self-induced polarization tracking, tunneling effect and modal attraction in optical fiber

    CERN Document Server

    Guasoni, Massimiliano; Bony, Pierre-Yves; Wabnitz, Stefan; Fatome, Julien

    2015-01-01

    In this paper, we report the observation and exploitation of the capability of light to self-organize its state-of-polarization, upon propagation in optical fibers, by means of a device called Omnipolarizer. The principle of operation of this system consists in a counter-propagating four-wave mixing interaction between an incident signal and its backward replica generated at the fiber output thanks to a reflective fiber loop. We have exploited this self-induced polarization tracking phenomenon for all-optical data processing and successfully demonstrated the spontaneous repolarization of a 40-Gbit/s On-Off keying optical signal without noticeable impairments. Moreover, the strong local coupling between the two counter-propagating waves has also revealed a fascinating aspect of the Omnipolarizer called polarization-based tunneling effect. This intrinsic property enables us to instantaneously let jump a polarization information onto the reflected signal, long before the expected time-of-flight induced by the ro...

  10. Strain effect on optical polarization properties of a -plane GaN on r -plane sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chao; Yu, Tongjun; Tao, Renchun; Jia, Chuanyu; Yang, Zhijian; Zhang, Guoyi [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, 100871 Beijing (China)

    2010-07-15

    In this study, the optical polarization properties under varying strains in a-plane GaN were investigated. The valence band (VB) structure for a-plane GaN is derived from the effective-mass Hamiltonian based on k.p perturbation theory. The relative oscillator strength (ROS) calculations of the transitions related to the top three VBs near {gamma} point are applied to analyzing the optical polarized properties. For a-plane GaN, the main components of the first, the second and the third VBs are vertical stroke Y right angle -like (y-axis //[1 anti 100]), vertical stroke Z right angle -like (z-axis //[0001]) and vertical stroke X right angle -like (x-axis //[11 anti 20]) states, respectively. Under small compressive strain along c-axis, the polarization degree increases with compressive strain increasing. According to X-ray diffraction (XRD) scans and Raman backscattering spectra, both the in-plane and out-plane strains were evaluated. Polarized photoluminescence (PL) is employed to obtain the polarization degree. The experimental results of a-plane GaN samples under different strains showed good accordance with our theoretical calculations (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Synchronous Optical and Radio Polarization Variability in the Blazar OJ287

    CERN Document Server

    D'Arcangelo, F D; Jorstad, S G; Smith, P S; Larionov, V M; Hagen-Thorn, V A; Williams, G G; Gear, W K; Clemens, D P; Sarcia, D; Grabau, A; Tollestrup, E V; Buie, M W; Taylor, B; Dunham, E

    2009-01-01

    We explore the variability and cross-frequency correlation of the flux density and polarization of the blazar OJ287, using imaging at 43 GHz with the Very Long Baseline Array, as well as optical and near-infrared polarimetry. The polarization and flux density in both the optical waveband and the 43 GHz compact core increased by a small amount in late 2005, and increased significantly along with the near-IR polarization and flux density over the course of 10 days in early 2006. Furthermore, the values of the electric vector position angle (EVPA) at the three wavebands are similar. At 43 GHz, the EVPA of the blazar core is perpendicular to the flow of the jet, while the EVPAs of emerging superluminal knots are aligned parallel to the jet axis. The core polarization is that expected if shear aligns the magnetic field at the boundary between flows of disparate velocities within the jet. Using variations in flux density, percentage polarization, and EVPA, we model the inner jet as a spine-sheath system. The model ...

  12. Circularly polarized few-optical-cycle solitons in the short-wave-approximation regime

    Energy Technology Data Exchange (ETDEWEB)

    Leblond, Herve [Laboratoire de Photonique d' Angers, EA 4464, Universite d' Angers, 2 Boulevard Lavoisier, F-49045 Angers Cedex 01 (France); Triki, Houria [Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Post Office Box 12, 23000 Annaba (Algeria); Mihalache, Dumitru [Laboratoire de Photonique d' Angers, EA 4464, Universite d' Angers, 2 Boulevard Lavoisier, F-49045 Angers Cedex 01 (France); Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), 407 Atomistilor, RO-077125 Magurele-Bucharest (Romania); Academy of Romanian Scientists, 54 Splaiul Independentei, RO-050094 Bucharest (Romania)

    2011-08-15

    We consider the propagation of few-cycle pulses (FCPs) beyond the slowly varying envelope approximation in media in which the dynamics of constituent atoms is described by a two-level Hamiltonian by taking into account the wave polarization. We consider the short-wave approximation, assuming that the resonance frequency of the two-level atoms is well below the inverse of the characteristic duration of the optical pulse. By using the reductive perturbation method (multiscale analysis), we derive from the Maxwell-Bloch-Heisenberg equations the governing evolution equations for the two polarization components of the electric field in the first order of the perturbation approach. We show that propagation of circularly polarized (CP) few-optical-cycle solitons is described by a system of coupled nonlinear equations, which reduces in the scalar case to the standard sine Gordon equation describing the dynamics of linearly polarized FCPs in the short-wave-approximation regime. By direct numerical simulations, we calculate the lifetime of CP FCPs, and we study the transition to two orthogonally polarized single-humped pulses as a generic route of their instability.

  13. Discovery of the Sub-second Linearly Polarized Spikes of Synchrotron Origin in the UV Ceti Giant Optical Flare

    Science.gov (United States)

    Beskin, G.; Karpov, S.; Plokhotnichenko, V.; Stepanov, A.; Tsap, Yu.

    2017-01-01

    During our optical monitoring of UV Ceti, iconic late-type flaring star, with high temporal resolution using the Russian 6-m telescope in 2008, we detected a giant flare with the amplitude of about 3 magnitudes in U band. Near flare maximum, more than a dozen of spike bursts have been discovered with triangular shapes and durations from 0.6 to 1.2 s and maximal luminosities in the range (1.5-8) × 1027 erg s-1. For the half of these events, the linear polarization exceeds 35% with significance better than 5σ. We argue that these events are synchrotron emission of electron streams with the energies of several hundred MeV moving in the magnetic field of about 1.4 kG. Emission from such ultra-relativistic (with energies far exceeding 10 MeV) particles is being routinely observed in solar flares, but has never been detected from UV Ceti-type stars. This is the first ever detection of linearly polarized optical light from the UV Ceti-type stars which indicates that at least some fraction of the flaring events on these stars is powered by a non-thermal synchrotron emission mechanism.

  14. The Polar SmartEdge heartrate-monitor`s estimation of an individual training-zone

    OpenAIRE

    Midtgaard, Helle

    2005-01-01

    The heartrate is a useful indication of intensity level. But it is big differences in maximum heartrate, and therefore also in the recommended heartrate at different intensity levels. The Polar SmartEdge heartrate-monitor estimates an individual training-zone (65-85% of maximum heartrate), based on the variability of the individuals heartrate. This zone is beneficial for improvement of the aerobic capacity and fat-burning. The variability of heartrate decreases for each person when the in...

  15. Optical Vector Network Analyzer with an Improved Dynamic Range Based on a Polarization Multiplexing Electro-Optic Modulator

    Science.gov (United States)

    Wang, Qi; Wang, Wen-Ting; Chen, Wei; Liu, Jian-Guo; Zhu, Ning-Hua

    2017-05-01

    We present a new method to achieve an optical vector network analyzer (OVNA) based on a polarization multiplexing electro-optic modulator (PM-EOM) without an optical bandpass filter. Optical single sideband (OSSB) modulated signals with a tunable optical carrier-sideband ratio (OCSR) are obtained at the output of the PM-EOM. The OCSR can be flexibly tuned by controlling bias voltages of the PM-EOM. The dynamic range of the OVNA is expanded by taking the improvement of the OCSR into account. The transmission response of an optical device under test (ODUT) is measured based on one-to-one mapping from optical domain to electrical domain. By optimizing the OCSR of the OSSB modulated signals, the dynamic range of the OVNA can be effectively improved with 3.7 dB. An analytical model is derived to describe the transfer function of the ODUT. The magnitude and phase responses of a fiber Bragg grating are characterized with a large dynamic range. Supported by the National Natural Science Foundation of China under Grant Nos 61377070, 61090391 and 61675196, and the National High-Technology Research and Development Program of China under Grant No 2013AA014203.

  16. Modeling the reverberation of optical polarization in AGN

    CERN Document Server

    Lobos, P Andrea Rojas; Marin, Frederic

    2016-01-01

    According to the standard paradigm, the strong and compact luminosity of active galactic nuclei (AGN) is due to multi-temperature black body emission originating from an accretion disk formed around a supermassive black hole. This central engine is thought to be surrounded by a dusty region along the equatorial plane and by ionized winds along the poles. The innermost regions cannot yet be resolved neither in the optical nor in the infrared and it is fair to say that we still lack a satisfactory understanding of the physical processes, geometry and composition of the central (sub-parsec) components of AGN. Like spectral or polarimetric observations, the reverberation data needs to be modeled in order to infer constraints on the AGN geometry (such as the inner radius or the half-opening angle of the dusty torus). In this research note, we present preliminary modeling results using a time-dependent Monte Carlo method to solve the radiative transfer in a simplified AGN set up. We investigate different model conf...

  17. Progress in modeling polarization optical components for the Daniel K. Inouye Solar Telescope

    Science.gov (United States)

    Sueoka, Stacey Ritsuyo; Harrington, David M.

    2016-07-01

    The DKIST will have a suite of first-light polarimetric instrumentation requiring precise calibration of a complex articulated optical path. The optics are subject to large thermal loads caused by the 300Watts of collected solar irradiance across the 5 arc minute field of view. The calibration process requires stable optics to generate known polarization states. We present modeling of several optical, thermal and mechanical effects of the calibration optics, the first transmissive optical elements in the light path, because they absorb substantial heat. Previous studies showed significant angle of incidence effects from the f/13 converging beam and the 5 arc minute field of view, but were only modeled at a single nominal temperature. New thermal and polarization modeling of these calibration retarders shows heating causes significant stability limitations both in time and with field caused by the bulk temperature rise along with depth and radial thermal gradients. Modeling efforts include varying coating and material absorption, Mueller matrix stability estimates and mitigation efforts.

  18. Monitoring changes of optical attenuation coefficients of acupuncture points during laser acupuncture by optical coherence tomography

    Science.gov (United States)

    Huang, Yimei; Yang, Hongqin; Wang, Yuhua; Zheng, Liqin; Xie, Shusen

    2010-11-01

    The physical properties of acupuncture point were important to discover the mechanism of acupuncture meridian. In this paper, we used an optical coherence tomography to monitor in vivo the changes of optical attenuation coefficients of Hegu acupuncture point and non-acupuncture point during laser irradiation on Yangxi acupuncture point. The optical attenuation coefficients of Hegu acupuncture point and non-acupuncture point were obtained by fitting the raw data according to the Beer-Lambert's law. The experimental results showed that the optical attenuation coefficient of Hegu acupuncture point decreased during the laser acupuncture, in contrast to a barely changed result in that of non-acupuncture point. The significant change of optical attenuation coefficient of Hegu acupuncture point indicated that there was a correlation between Hegu and Yangxi acupuncture points to some extent.

  19. An improved calibration method using third order polarization mode crosstalk for optical coherence domain polarimetry

    Science.gov (United States)

    Yang, Zhe; Yang, Jun; Zhang, Haoliang; Li, Hanyang; Peng, Feng; Yuan, Yonggui; Cheng, Yongqing; Yuan, Libo

    2017-04-01

    We propose an improved optical coherence domain polarimetry (OCDP) calibration scheme by using polarization mode crosstalk (PMC). The scheme can be used to calibrate the OCDP system's measurement result about intensity of PMC. The intensity of 1st order PMCs are measured by polarization extinction ratio (PER) meter as the scale to transfer the standard into OCDP system, and the higher order PMCs formed by 1st orders are used to expand the scale. Specifying alignment angle of joint points and analyzer, we successfully use 3rd order PMCs and expand the range of calibration over -100 dB.

  20. Polarization-induced noise in a fiber-optic Michelson interferometer with Faraday rotator mirror elements.

    Science.gov (United States)

    Ferreira, L A; Santos, J L; Farahi, F

    1995-10-01

    Faraday rotator mirror elements have been used in a number of applications as compensators for induced birefringence in retracing paths. In interferometric systems, such as the fiber-optic Michelson interferometer, this approach proved to be useful in providing maximum fringe visibility and insensitivity to the polarization state of light injected into the interferometer. However, it is found that, when the characteristics of the fiber coupler depend on the polarization state of the input beam, the efficiency of the Faraday mirror elements is limited. Theoretical analysis and experimental results in support of this statement are presented.

  1. Polarization-induced noise in a fiber-optic Michelson interferometer with Faraday rotator mirror elements

    Science.gov (United States)

    Ferreira, L. A.; Santos, J. L.; Farahi, F.

    1995-10-01

    Faraday rotator mirror elements have been used in a number of applications as compensators for induced birefringence in retracing paths. In interferometric systems, such as the fiber-optic Michelson interferometer, this approach proved to be useful in providing maximum fringe visibility and insensitivity to the polarization state of light injected into the interferometer. However, it is found that, when the characteristics of the fiber coupler depend on the polarization state of the input beam, the efficiency of the Faraday mirror elements is limited. Theoretical analysis and experimental results in support of this statement are presented.

  2. Swings and roundabouts: optical Poincaré spheres for polarization and Gaussian beams

    Science.gov (United States)

    Dennis, M. R.; Alonso, M. A.

    2017-02-01

    The connection between Poincaré spheres for polarization and Gaussian beams is explored, focusing on the interpretation of elliptic polarization in terms of the isotropic two-dimensional harmonic oscillator in Hamiltonian mechanics, its canonical quantization and semiclassical interpretation. This leads to the interpretation of structured Gaussian modes, the Hermite-Gaussian, Laguerre-Gaussian and generalized Hermite-Laguerre-Gaussian modes as eigenfunctions of operators corresponding to the classical constants of motion of the two-dimensional oscillator, which acquire an extra significance as families of classical ellipses upon semiclassical quantization. This article is part of the themed issue 'Optical orbital angular momentum'.

  3. Slim-structured electro-floating display system based on the polarization-controlled optical path.

    Science.gov (United States)

    Kim, Seung-Cheol; Park, Seong-Jin; Kim, Eun-Soo

    2016-04-18

    A new slim-type electro-floating display system based on the polarization-controlled optical path is proposed. In the proposed system, the optical path between the input plane and Fresnel lens can be made recursive by repetitive transmission and reflection of the input beam by employing a new polarization-based optical path controller (P-OPC), which is composed of two quaterwave plates, a half mirror and a reflective polarizer. Based on this P-OPC, the absolute optical path between the input plane and Fresnel lens, virtually representing the physical depth of the display system, can be reduced down to one third of its original path, which results in the same rate of decrease in the volume size of the display system. The operational principle of the proposed system is analyzed with the Jones matrix. In addition, to confirm the feasibility of the proposed system, experiments with test prototypes are carried out, and the results are comparatively discussed with those of the conventional system.

  4. A quantum gas of polar KRb molecules in an optical lattice

    Science.gov (United States)

    Covey, Jacob; Miecnikowski, Matthew; Moses, Steven; Fu, Zhengkun; Jin, Deborah; Ye, Jun

    2016-05-01

    Ultracold polar molecules provide new opportunities for investigation of strongly correlated many-body spin systems such as many-body localization and quantum magnetism. In an effort to access such phenomena, we load polar KRb molecules into a three-dimensional optical lattice. In this system, we observed many-body spin dynamics between molecules pinned in a deep lattice, even though the filling fraction of the molecules was only 5%. We have recently performed a thorough investigation of the molecule creation process in an optical lattice, and consequently improved our filling fraction to 30% by preparing and overlapping Mott and band insulators of the initial atomic gases. More recently, we switched to a second generation KRb apparatus that will allow application of large, stable electric fields as well as high-resolution addressing and detection of polar molecules in optical lattices. We plan to use these capabilities to study non-equilibrium spin dynamics in an optical lattice with nearly single site resolution. I will present the status and direction of the second generation apparatus.

  5. Low-Entropy States of Neutral Atoms in Polarization-Synthesized Optical Lattices.

    Science.gov (United States)

    Robens, Carsten; Zopes, Jonathan; Alt, Wolfgang; Brakhane, Stefan; Meschede, Dieter; Alberti, Andrea

    2017-02-10

    We create low-entropy states of neutral atoms by utilizing a conceptually new optical-lattice technique that relies on a high-precision, high-bandwidth synthesis of light polarization. Polarization-synthesized optical lattices provide two fully controllable optical lattice potentials, each of them confining only atoms in either one of the two long-lived hyperfine states. By employing one lattice as the storage register and the other one as the shift register, we provide a proof of concept using four atoms that selected regions of the periodic potential can be filled with one particle per site. We expect that our results can be scaled up to thousands of atoms by employing an atom-sorting algorithm with logarithmic complexity, which is enabled by polarization-synthesized optical lattices. Vibrational entropy is subsequently removed by sideband cooling methods. Our results pave the way for a bottom-up approach to creating ultralow-entropy states of a many-body system.

  6. Broadband polarization interferometric time-integrating acousto-optic correlator for random noise radar

    Science.gov (United States)

    Kim, Sangtaek; Wagner, Kelvin H.; Narayanan, Ram M.; Zhou, Wei

    2005-10-01

    We describe a time-integrating acousto-optic correlator (TIAOC) developed for imaging and target detection using a wideband random-noise radar system. This novel polarization interferometric in-line TIAOC uses an intensity-modulated laser diode for the random noise reference and a polarization-switching, self-collimating acoustic shear-mode gallium phosphide (GaP) acousto-optic device for traveling-wave modulation of the radar returns. The time-integrated correlation output is detected on a 1-D charge-coupled device (CCD) detector array and calibrated and demodulated in real time to produce the complex radar range profile. The complex radar reflectivity is measured in more than 150 radar range bins in parallel on the 3000 pixels of the CCD, improving target acquisition speeds and sensitivities by 150 over previous serial analog correlator approaches. The polarization interferometric detection of the correlation using the undiffracted light as the reference allows us to use the full acousto-optic device (AOD) bandwidth as the system bandwidth. Also, the experimental result shows the fully complex random-noise signal correlation and coherent demodulation without an explicit carrier, demonstrating that optically processed random-noise radars do not need a stable local oscillator.

  7. A recent change in the optical and γ-ray polarization of the Crab nebula and pulsar

    Science.gov (United States)

    Moran, P.; Kyne, G.; Gouiffès, C.; Laurent, P.; Hallinan, G.; Redfern, R. M.; Shearer, A.

    2016-03-01

    We report on observations of the polarization of optical and γ-ray photons from the Crab nebula and pulsar system using the Galway Astronomical Stokes Polarimeter (GASP), the Hubble Space Telescope, Advanced Camera for Surveys and the International Gamma-Ray Astrophysics Laboratory satellite (INTEGRAL). These, when combined with other optical polarization observations, suggest that the polarized optical emission and γ-ray polarization changes in a similar manner. A change in the optical polarization angle has been observed by this work, from 109.5 ± 0.7° in 2005 to 85.3 ± 1.4° in 2012. On the other hand, the γ-ray polarization angle changed from 115 ± 11° in 2003-2007 to 80 ± 12° in 2012-2014. Strong flaring activities have been detected in the Crab nebula over the past few years by the high-energy γ-ray missions Agile and Fermi, and magnetic reconnection processes have been suggested to explain these observations. The change in the polarized optical and γ-ray emission of the Crab nebula/pulsar as observed, for the first time, by GASP and INTEGRAL may indicate that reconnection is possibly at work in the Crab nebula. We also report, for the first time, a non-zero measure of the optical circular polarization from the Crab pulsar+knot system.

  8. Signature Optical Cues: Emerging Technologies for Monitoring Plant Health

    Directory of Open Access Journals (Sweden)

    Anand K. Asundi

    2008-05-01

    Full Text Available Optical technologies can be developed as practical tools for monitoring plant health by providing unique spectral signatures that can be related to specific plant stresses. Signatures from thermal and fluorescence imaging have been used successfully to track pathogen invasion before visual symptoms are observed. Another approach for noninvasive plant health monitoring involves elucidating the manner with which light interacts with the plant leaf and being able to identify changes in spectral characteristics in response to specific stresses. To achieve this, an important step is to understand the biochemical and anatomical features governing leaf reflectance, transmission and absorption. Many studies have opened up possibilities that subtle changes in leaf reflectance spectra can be analyzed in a plethora of ways for discriminating nutrient and water stress, but with limited success. There has also been interest in developing transgenic phytosensors to elucidate plant status in relation to environmental conditions. This approach involves unambiguous signal creation whereby genetic modification to generate reporter plants has resulted in distinct optical signals emitted in response to specific stressors. Most of these studies are limited to laboratory or controlled greenhouse environments at leaf level. The practical translation of spectral cues for application under field conditions at canopy and regional levels by remote aerial sensing remains a challenge. The movement towards technology development is well exemplified by the Controlled Ecological Life Support System under development by NASA which brings together technologies for monitoring plant status concomitantly with instrumentation for environmental monitoring and feedback control.

  9. Possibilities in optical monitoring of laser welding process

    Science.gov (United States)

    Horník, Petr; Mrňa, Libor; Pavelka, Jan

    2016-11-01

    Laser welding is a modern, widely used but still not really common method of welding. With increasing demands on the quality of the welds, it is usual to apply automated machine welding and with on-line monitoring of the welding process. The resulting quality of the weld is largely affected by the behavior of keyhole. However, its direct observation during the welding process is practically impossible and it is necessary to use indirect methods. At ISI we have developed optical methods of monitoring the process. Most advanced is an analysis of radiation of laser-induced plasma plume forming in the keyhole where changes in the frequency of the plasma bursts are monitored and evaluated using Fourier and autocorrelation analysis. Another solution, robust and suitable for industry, is based on the observation of the keyhole inlet opening through a coaxial camera mounted in the welding head and the subsequent image processing by computer vision methods. A high-speed camera is used to understand the dynamics of the plasma plume. Through optical spectroscopy of the plume, we can study the excitation of elements in a material. It is also beneficial to monitor the gas flow of shielding gas using schlieren method.

  10. Nonlinear optical responses to circularly polarized lights of the surface state of a topological insulator

    Science.gov (United States)

    Misawa, Tetsuro; Yokoyama, Takehito; Murakami, Shuichi

    2012-02-01

    Recent photoelectron spectroscopy experiments have revealed the presence of the Dirac cone on the surface of the topological insulator and its spin-splitting due to the spin-orbit interaction. In general, on spin-orbit coupled systems, electric fields induce spin polarizations as linear and nonlinear responses. Here we investigate the inverse Faraday effect on the surface of the topological insulator. The inverse Faraday effect is a non-linear optical effect where a circularly polarized light induces a dc spin polarization. We employ the Keldysh Green's function method to calculate the induced spin polarization and discuss its frequency dependence. In particular, in the low frequency limit, our analytical result gives the spin polarization proportional to the frequency and the square of the lifetime. As for the finite frequency regime, we employ numerical methods to discuss the resonance due to interband transitions. We also discuss the photogalvanic effect, where an illumination of a circular polarized light generates the dc charge current. Lastly, we evaluate those quantities with realistic parameters.[4pt] [1] T. Misawa, T. Yokoyama, S. Murakami, Phys. Rev. B84, 165407 (2011).

  11. Circular polarization switching and bistability in an optically injected 1300 nm spin-vertical cavity surface emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Alharthi, S. S., E-mail: ssmalh@essex.ac.uk; Henning, I. D.; Adams, M. J. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Hurtado, A. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Institute of Photonics, Physics Department, University of Strathclyde, Wolfson Centre, 106 Rottenrow East, Glasgow G4 0NW, Scotland (United Kingdom); Korpijarvi, V.-M.; Guina, M. [Optoelectronics Research Centre (ORC), Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)

    2015-01-12

    We report the experimental observation of circular polarization switching (PS) and polarization bistability (PB) in a 1300 nm dilute nitride spin-vertical cavity surface emitting laser (VCSEL). We demonstrate that the circularly polarized optical signal at 1300 nm can gradually or abruptly switch the polarization ellipticity of the spin-VCSEL from right-to-left circular polarization and vice versa. Moreover, different forms of PS and PB between right- and left-circular polarizations are observed by controlling the injection strength and the initial wavelength detuning. These results obtained at the telecom wavelength of 1300 nm open the door for novel uses of spin-VCSELs in polarization sensitive applications in future optical systems.

  12. Polarization-, carrier-, and format-selectable optical flow generation based on a multi-flow transmitter using passive polymers

    DEFF Research Database (Denmark)

    Katopodis, V.; Spyropoulou, M.; Tsokos, C.;

    2016-01-01

    . Multiflow operation is realized by two polymer boards allowing optical carrier management and optional polarization multiplexing on chip. Optical carrier generation is performed also on chip using three tunable InP gain chips hybridly integrated on the input polyboard. Single and dual optical flow...

  13. Effects of Si-doping on structural, electrical, and optical properties of polar and non-polar AlGaN epi-layers

    Science.gov (United States)

    Yang, Hongquan; Zhang, Xiong; Wang, Shuchang; Wang, Yi; Luan, Huakai; Dai, Qian; Wu, Zili; Zhao, Jianguo; Cui, Yiping

    2016-08-01

    The polar (0001)-oriented c-plane and non-polar (11 2 bar 0) -oriented a-plane wurtzite AlGaN epi-layers were successfully grown on polar (0001)-oriented c-plane and semi-polar (1 1 bar 02) -oriented r-plane sapphire substrates, respectively with various Si-doping levels in a low pressure metal organic chemical vapor deposition (MOCVD) system. The morphological, structural, electrical, and optical properties of the polar and non-polar AlGaN epi-layers were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), Hall effect, and Raman spectroscopy. The characterization results show that Si dopants incorporated into the polar and non-polar AlGaN films induced a relaxation of compressive residual strain and a generation of biaxial tensile strain on the surface in consequence of the dislocation climbing. In particular, it was found that the Si-induced compressive strain relaxation in the non-polar AlGaN samples can be promoted by the structural anisotropy as compared with the polar counterparts. The gradually increased relaxation of compressive residual strain in both polar and non-polar AlGaN samples with increasing Si-doping level was attributed to the Si-induced enhancement in the opportunity for the dislocations to interact and annihilate. This implies that the crystal quality for both polar and non-polar AlGaN epi-layers can be remarkably improved by Si-doping.

  14. Three-dimensional analysis of optical forces generated by an active tractor beam using radial polarization.

    Science.gov (United States)

    Carretero, Luis; Acebal, Pablo; Blaya, Salvador

    2014-02-10

    We theoretically study the three-dimensional behavior of nanoparticles in an active optical conveyor. To do this, we solved the Langevin equation when the forces are generated by a focusing system at the near field. Analytical expressions for the optical forces generated by the optical conveyor were obtained by solving the Richards and Wolf vectorial diffraction integrals in an approximated form when a mask of two annular pupils is illuminated by a radially polarized Hermite-Gauss beam. Trajectories, in both the transverse plane and the longitudinal direction, are analyzed showing that the behavior of the optical conveyor can be optimized by conveniently choosing the configuration of the mask of the two annular pupils (inner and outer radius of the two rings) in order to trap and transport all particles at the focal plane.

  15. Concurrent validity of resting pulse-rate measurements: a comparison of 2 smartphone applications, the polar H7 belt monitor, and a pulse oximeter with bluetooth.

    Science.gov (United States)

    Cheatham, Scott W; Kolber, Morey J; Ernst, Michael P

    2015-05-01

    Pulse rate is commonly measured manually or with commercial wrist or belt monitors. More recently, pulse-rate monitoring has become convenient with the use of mobile technology that allows monitoring through a smartphone camera. This optical technology offers many benefits, although the clinimetric properties have not been extensively studied. Observational study of reliability Setting: University kinesiology laboratory. 30 healthy, recreationally active adults. Concurrent measurement of pulse rate using 2 smartphone applications (fingertip, face-scan,) with the Polar H7 belt and pulse oximeter. Average resting pulse rate for 5 min in 3 positions (supine, sitting, and prone). Concurrent validity in supine and standing was good between the 2 applications and the Polar H7 (intraclass correlation coefficient [ICC] .80-.98) and pulse oximeter (ICC .82-.98). For sitting, the validity was good between the fingertip application, Polar H7 (ICC .97), and pulse oximeter (ICC .97). The face-scan application had moderate validity with the Polar H7 (ICC .74) and pulse oximeter (ICC .69). The minimal detectable change (MDC90) between the fingertip application and Polar H7 ranged from 1.38 to 4.36 beats/min (BPM) and from 0.69 to 2.97 BPM for the pulse oximeter with both positions. The MDC90 between the face-scan application and Polar H7 ranged from 11.88 to 12.83 BPM and from 0.59 to 17.72 BPM for the pulse oximeter. The 95% limits of agreement suggest that the fingertip application may vary between 2.40 and 3.59 BPM with the Polar H7 and between 3.40 and 3.42 BPM with the pulse oximeter. The face-scan application may vary between 3.46 and 3.52 BPM with the Polar H7 and between 2.54 and 3.46 BPM with the pulse oximeter. Pulse-rate measurements may be effective using a fingertip application, belt monitor, and pulse oximeter. The fingertip scanner showed superior results compared with the face scanner, which only demonstrated modest validity compared with the Polar H7 and pulse

  16. Impact of unpredictability on chaos synchronization of vertical-cavity surface-emitting lasers with variable-polarization optical feedback.

    Science.gov (United States)

    Xiang, Shuiying; Pan, Wei; Yan, Lianshan; Luo, Bin; Zou, Xihua; Jiang, Ning; Yang, Lei

    2011-09-01

    The effects of unpredictability degree on the chaos synchronization properties of vertical-cavity surface-emitting lasers with variable-polarization optical feedback are investigated numerically. For variable-polarization optical injection, only low-unpredictability chaos can be well synchronized, while high-unpredictability chaos cannot be synchronized even with large injection strength. On the other hand, for the polarization-preserved optical injection, the synchronization quality is hardly affected by the unpredictability degree, and high-quality synchronization can be achieved for both low- and high-unpredictability chaos due to injection locking.

  17. Polarization Sensitive Optical Coherence Tomography: A Review of Technology and Applications

    Directory of Open Access Journals (Sweden)

    Bernhard Baumann

    2017-05-01

    Full Text Available Polarization sensitive optical coherence tomography (PS-OCT is an imaging technique based on light scattering. PS-OCT performs rapid two- and three-dimensional imaging of transparent and translucent samples with micrometer scale resolution. PS-OCT provides image contrast based on the polarization state of backscattered light and has been applied in many biomedical fields as well as in non-medical fields. Thereby, the polarimetric approach enabled imaging with enhanced contrast compared to standard OCT and the quantitative assessment of sample polarization properties. In this article, the basic methodological principles, the state of the art of PS-OCT technologies, and important applications of the technique are reviewed in a concise yet comprehensive way.

  18. An integrable optical-fiber source of polarization entangled photon-pairs in the telecom band

    CERN Document Server

    Li, X; Kumar, P; Lee, K F; Liang, C; Voss, P L; Chen, Jun; Kumar, Prem; Lee, Kim Fook; Li, Xiaoying; Liang, Chuang; Voss, Paul L.

    2006-01-01

    We demonstrate an optical-fiber based source of polarization entangled photon-pairs with improved quality and efficiency, which has been integrated with off-the-shelf telecom components and is, therefore, well suited for quantum communication applications in the 1550\\,nm telecom band. Polarization entanglement is produced by simultaneously pumping a loop of standard dispersion-shifted fiber with two orthogonally-polarized pump pulses, one propagating in the clockwise and the other in the counter-clockwise direction. We characterize this source by investigating two-photon interference between the generated signal-idler photon-pairs under various conditions. The experimental parameters are carefully optimized to maximize the generated photon-pair correlation and to minimize contamination of the entangled photon-pairs from extraneously scattered background photons that are produced by the pump pulses for two reasons: i) spontaneous Raman scattering causes uncorrelated photons to be emitted in the signal/idler ba...

  19. Optical-fiber source of polarization-entangled photon pairs in the 1550nm telecom band

    CERN Document Server

    Li, X; Sharping, J E; Kumar, P; Li, Xiaoying; Voss, Paul L.; Sharping, Jay E.; Kumar, Prem

    2005-01-01

    We present a fiber based source of polarization-entangled photon pairs that is well suited for quantum communication applications in the 1550nm band of standard fiber-optic telecommunications. Polarization entanglement is created by pumping a nonlinear-fiber Sagnac interferometer with two time-delayed orthogonally-polarized pump pulses and subsequently removing the time distinguishability by passing the parametrically scattered signal-idler photon pairs through a piece of birefringent fiber. Coincidence detection of the signal-idler photons yields biphoton interference with visibility greater than 90%, while no interference is observed in direct detection of either the signal or the idler photons. All four Bell states can be prepared with our setup and we demonstrate violations of CHSH form of Bell's inequalities by up to 10 standard deviations of measurement uncertainty.

  20. Tailoring the interaction between matter and polarized light with plasmonic optical antennas

    Science.gov (United States)

    Biagioni, P.; Wu, X.; Savoini, M.; Ziegler, J.; Huang, J.-S.; Duò, L.; Finazzi, M.; Hecht, B.

    2011-03-01

    We explore the possibility to control the polarization state of light confined into sub-diffraction volumes by means of plasmonic optical antennas. To this aim, we describe a resonant cross antenna, constituted of two perpendicular two-wire antennas sharing the same gap, which is able to maintain the polarization state in the plane of the antenna. We also discuss how, by proper tuning of the arm length in a slightly off-resonance cross antenna, it is possible to effectively realize a nanoscale quarter-waveplate antenna. We present experimental results for the preparation of individual cross antennas by means of focused ion beam milling starting from single-crystalline Au microflakes, and finally show preliminary characterization results based on two-photon photoluminescence confocal imaging with linearly-polarized light.

  1. Distributed optical fiber sensor for spatial location of polarization mode coupling

    Science.gov (United States)

    Cokgor, Ilkan; Handerek, Vincent A.; Rogers, Alan J.

    1993-03-01

    Transverse stress applied to a highly birefringent fiber at an arbitrary angle (other than 0 or 90 degrees) to the fiber birefringence axes causes rotation of the birefringence axes and changes the beat length of the fiber in that section. If one of the polarization modes is excited at the input, coupling of light from one mode to the other will be observed at a stress point. The presentation describes a method for determining the locations of discrete mode coupling points spaced along a polarization maintaining fiber using a pump-prob architecture based on the optical Kerr effect. Probe light experiences coupling at different stress locations. Counterpropagating strong pump light also experiences coupling while inducing additional birefringence, and changing the polarization state of the probe at the output. This system may be made temperature independent by introducing a phase tracking/triggering system. The advantages and limitations of this technique are described.

  2. RoboPol: Do optical polarization rotations occur in all blazars?

    CERN Document Server

    Blinov, D; Papadakis, I; Kiehlmann, S; Liodakis, I; Panopoulou, G V; Pearson, T J; Angelakis, E; Baloković, M; Hovatta, T; Joshi, V; King, O G; Kus, A; Kylafis, N; Mahabal, A; Marecki, A; Myserlis, I; Paleologou, E; Papamastorakis, I; Pazderski, E; Prabhudesai, S; Ramaprakash, A; Readhead, A C S; Reig, P; Tassis, K; Zensus, J A

    2016-01-01

    We present a new set of optical polarization plane rotations in blazars, observed during the third year of operation of RoboPol. The entire set of rotation events discovered during three years of observations is analysed with the aim of determining whether these events are inherent in all blazars. It is found that the frequency of the polarization plane rotations varies widely among blazars. This variation cannot be explained either by a difference in the relativistic boosting or by selection effects caused by a difference in the average fractional polarization. We conclude that the rotations are characteristic of a subset of blazars and that they occur as a consequence of their intrinsic properties.

  3. Passive all-optical polarization switch, binary logic gates, and digital processor.

    Science.gov (United States)

    Zaghloul, Y A; Zaghloul, A R M; Adibi, A

    2011-10-10

    We introduce the passive all-optical polarization switch, which modulates light with light. That switch is used to construct all the binary logic gates of two or more inputs. We discuss the design concepts and the operation of the AND, OR, NAND, and NOR gates as examples. The rest of the 16 logic gates are similarly designed. Cascading of such gates is straightforward as we show and discuss. Cascading in itself does not require a power source, but feedback at this stage of development does. The design and operation of an SR Latch is presented as one of the popular basic sequential devices used for memory cells. That completes the essential components of an all-optical polarization digital processor. The speed of such devices is well above 10 GHz for bulk implementations and is much higher for chip-size implementations. In addition, the presented devices do have the four essential characteristics previously thought unique to the microelectronic ones.

  4. Fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser

    Science.gov (United States)

    Kuang, Zeyuang; Cheng, Linghao; Liang, Yizhi; Liang, Hao; Guan, Bai-Ou

    2015-07-01

    A fiber-optic Doppler velocimeter based on a dual-polarization fiber grating laser is demonstrated. The fiber grating laser produces two orthogonally polarized laser outputs with their frequency difference proportional to the intra-cavity birefringence. When the laser outputs are reflected from a moving targets, the laser frequencies will be shifted due to the Doppler effect. It shows that the frequency difference between the beat note of the laser outputs and the beat note of the reflected lasers is proportional to the velocity. The proposed fiber-optic Doppler velocimeter shows a high sensitivity of 0.64 MHz/m/s and is capable of measurement of wide range of velocity.

  5. Correlated X-ray and optical variability in intermediate polars during their outbursts

    CERN Document Server

    Neustroev, V V; Suleimanov, V; Sjoberg, G

    2016-01-01

    We present a study of the evolution of the optical and X-ray fluxes during outbursts of two short-period cataclysmic variables, the confirmed intermediate polar CC Scl and the intermediate polar candidate FS Aur. We found that the X-ray and optical light curves are well correlated in both objects, although the amplitudes of outbursts in X-rays are smaller than those in the optical. The ratio of the outburst amplitudes in X-rays and the optical in both objects is close to ~0.6. This is significantly higher than was observed during the outburst of the non-magnetic dwarf nova U Gem, in which this ratio was only ~0.03. The obtained data also suggest that the dependence between the X-ray and optical fluxes must steepen significantly toward very low accretion rates and very low fluxes. Similarities in the behaviour of CC Scl and FS Aur indicate strongly the magnetic nature of the white dwarf in FS Aur.

  6. Influence of Acoustic Field Structure on Polarization Characteristics of Acousto-optic Interaction in Crystals

    Science.gov (United States)

    Muromets, A. V.; Trushin, A. S.

    Influence of acoustic field structure on polarization characteristics of acousto-optic interaction is investigated. It is shown that inhomogeneity of acoustic field and mechanism of ultrasound excitation causes changes in values of acousto-optic figure of merit for ordinary and extraordinary light beams in comparison with theoretic values. The theoretic values were derived under assumption that acoustic wave is homogeneous. Experimental analysis was carried out in acousto-optic cell based on lithium niobate crystal where the acoustic wave propagates at the angle 13 degrees to Z axis of the crystal. We used three different methods of ultrasound generation in the crystal: by means of external piezotransducer, by interdigital transducer and by two sets of electrodes placed on top of the crystal surface. In the latter case, the first pair of the electrodes was directed along X crystal axis, while the second pair of the electrodes was directed orthogonally to X crystal axis and the direction of ultrasound. Obtained values for diffraction efficiencies for ordinary and extraordinary polarized optical beams were qualitatively different which may be caused by spatial inhomogeneity of the generated acoustic waves in the crystal. Structure of acoustic field generated by these sets of electrodes was examined by laser probing. We performed the analysis of the acoustic field intensity using acousto-optic method. A relation of diffraction efficiencies for ordinary and extraordinary light waves was measured during each iteration of the laser probing.

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

    Science.gov (United States)

    Liu, Yang

    2016-05-01

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

  8. Study of fiber-optic current sensing based on degree of polarization measurement

    Institute of Scientific and Technical Information of China (English)

    Feng Liu; Qing Ye; Jianxin Geng; Ronghui Qu; Zujie Fang

    2007-01-01

    A novel fiber-optic current sensing scheme is proposed by converting the Faraday rotation to the optical signal's degree of polarization (DOP) change. In this scheme, the lightwave passes through a fiber resonant cavity multiply and experiences Faraday rotation simultaneously. Its main merit is immunity from the environment disturbance to the fiber used in ordinary Faraday rotation sensor. Brief theoretical analysis and simulation are given to show its basic characteristics. Experimental results are demonstrated and the feasibility of the proposed method is also shown.

  9. An all-optical buffer based on polarization rotation in an EAM

    Institute of Scientific and Technical Information of China (English)

    Wang Kui-Ru; Kuang Hai; Wang Yong-Jun; Yuan Jin-Hui; Yan Bin-Bin

    2013-01-01

    A theoretical model of the refractive index changes of the TE and TM modes in an electro-absorption modulator (EAM) is deduced.The photon absorption and refractive index changes are analyzed numerically.The influence of pump intensity on the phase difference between the TE and TM modes is studied.The polarization rotation effect is obtained in the EAM,and a novel all-optical fiber loop buffer is designed.

  10. Distributed optical fiber vibration sensor based on spectrum analysis of Polarization-OTDR system.

    Science.gov (United States)

    Zhang, Ziyi; Bao, Xiaoyi

    2008-07-07

    A fully distributed optical fiber vibration sensor is demonstrated based on spectrum analysis of Polarization-OTDR system. Without performing any data averaging, vibration disturbances up to 5 kHz is successfully demonstrated in a 1km fiber link with 10m spatial resolution. The FFT is performed at each spatial resolution; the relation of the disturbance at each frequency component versus location allows detection of multiple events simultaneously with different and the same frequency components.

  11. Science Data Report for the Optical Properties Monitor (OPM) Experiment

    Science.gov (United States)

    Wilkes, D. R.; Zwiener, J. M.; Carruth, Ralph (Technical Monitor)

    2001-01-01

    This science data report describes the Optical Properties Monitor (OPM) experiment and the data gathered during its 9-mo exposure on the Mir space station. Three independent optical instruments made up OPM: an integrating sphere spectral reflectometer, vacuum ultraviolet spectrometer, and a total integrated scatter instrument. Selected materials were exposed to the low-Earth orbit, and their performance monitored in situ by the OPM instruments. Coinvestigators from four NASA Centers, five International Space Station contractors, one university, two Department of Defense organizations, and the Russian space company, Energia, contributed samples to this experiment. These materials included a number of thermal control coatings, optical materials, polymeric films, nanocomposites, and other state-of-the-art materials. Degradation of some materials, including aluminum conversion coatings and Beta cloth, was greater than expected. The OPM experiment was launched aboard the Space Shuttle on mission STS-81 in January 1997 and transferred to the Mir space station. An extravehicular activity (EVA) was performed in April 1997 to attach the OPM experiment to the outside of the Mir/Shuttle Docking Module for space environment exposure. OPM was retrieved during an EVA in January 1998 and was returned to Earth on board the Space Shuttle on mission STS-89.

  12. Distributed acoustic fibre optic sensors for condition monitoring of pipelines

    Science.gov (United States)

    Hussels, Maria-Teresa; Chruscicki, Sebastian; Habib, Abdelkarim; Krebber, Katerina

    2016-05-01

    Industrial piping systems are particularly relevant to public safety and the continuous availability of infrastructure. However, condition monitoring systems based on many discrete sensors are generally not well-suited for widespread piping systems due to considerable installation effort, while use of distributed fibre-optic sensors would reduce this effort to a minimum. Specifically distributed acoustic sensing (DAS) is employed for detection of third-party threats and leaks in oil and gas pipelines in recent years and can in principle also be applied to industrial plants. Further possible detection routes amenable by DAS that could identify damage prior to emission of medium are subject of a current project at BAM, which aims at qualifying distributed fibre optic methods such as DAS as a means for spatially continuous monitoring of industrial piping systems. Here, first tests on a short pipe are presented, where optical fibres were applied directly to the surface. An artificial signal was used to define suitable parameters of the measurement system and compare different ways of applying the sensor.

  13. Polarization-sensitive optical coherence tomography for imaging of biological tissues

    Science.gov (United States)

    Chen, Xiaodong; Wang, Yi; Li, Wanhui; Yu, Daoyin

    2006-09-01

    Polarization sensitive optical coherence tomography (PS-OCT) is a new non-contact and non-invasive method for measuring the change of birefringence in biological tissues caused by pathological changes of body. It has great potential in imaging the structural properties of turbid biological media because the polarization state of light backscattered from biological tissues is influenced by the birefringence of fibrous structures. The arrangement is based on a Michelson interferometer with use of quarter-wave plates and polarimeter. Through the detection of light backscattered from biological tissues and reflected from a reference mirror, the optical phase delay between orthogonal polarization compositions propagating in the birefringence media can be measured. PS-OCT is a powerful tool for research of tendon, dentin, lesions, which have strong polarization effective. We in this paper describe the experimental scheme and its mathematical representation, along with the theory of PS-OCT imaging. Besides, we introduce a fiber-based PS-OCT system for measuring the tissue birefringence.

  14. Optical cooling and trapping of highly magnetic atoms: the benefits of a spontaneous spin polarization

    Science.gov (United States)

    Dreon, Davide; Sidorenkov, Leonid A.; Bouazza, Chayma; Maineult, Wilfried; Dalibard, Jean; Nascimbene, Sylvain

    2017-03-01

    From the study of long-range-interacting systems to the simulation of gauge fields, open-shell lanthanide atoms with their large magnetic moment and narrow optical transitions open novel directions in the field of ultracold quantum gases. As for other atomic species, the magneto-optical trap (MOT) is the working horse of experiments but its operation is challenging, due to the large electronic spin of the atoms. Here we present an experimental study of narrow-line dysprosium MOTs. We show that the combination of radiation pressure and gravitational forces leads to a spontaneous polarization of the electronic spin. The spin composition is measured using a Stern–Gerlach separation of spin levels, revealing that the gas becomes almost fully spin-polarized for large laser frequency detunings. In this regime, we reach the optimal operation of the MOT, with samples of typically 3× {10}8 atoms at a temperature of 15 μK. The spin polarization reduces the complexity of the radiative cooling description, which allows for a simple model accounting for our measurements. We also measure the rate of density-dependent atom losses, finding good agreement with a model based on light-induced Van der Waals forces. A minimal two-body loss rate β ∼ 2× {10}-11 cm3 s–1 is reached in the spin-polarized regime. Our results constitute a benchmark for the experimental study of ultracold gases of magnetic lanthanide atoms.

  15. Optically initialized robust valley-polarized holes in monolayer WSe2

    KAUST Repository

    Hsu, Wei-Ting

    2015-11-25

    A robust valley polarization is a key prerequisite for exploiting valley pseudospin to carry information in next-generation electronics and optoelectronics. Although monolayer transition metal dichalcogenides with inherent spin–valley coupling offer a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time-resolved Kerr rotation spectroscopy, we observe a long-lived valley polarization for positive trion with a lifetime approaching 1 ns at low temperatures, which is much longer than the trion recombination lifetime (~10–20 ps). The long-lived valley polarization arises from the transfer of valley pseudospin from photocarriers to resident holes in a specific valley. The optically initialized valley pseudospin of holes remains robust even at room temperature, which opens up the possibility to realize room-temperature valleytronics based on transition metal dichalcogenides.

  16. Optical monitoring of high power direct diode laser cladding

    Science.gov (United States)

    Liu, Shuang; Farahmand, Parisa; Kovacevic, Radovan

    2014-12-01

    Laser cladding is one of the most advanced surface modification techniques which can be used to build and repair high-value components. High power direct diode laser (HPDDL) offers unique quality and cost advantages over other lasers (CO2, Nd:YAG). Especially its rectangular laser beam with top-hat intensity distribution makes HPDDL an ideal tool for large area cladding. In order to utilize this technique successfully, the development of on-line monitoring and process control is necessary. In this study, an optical monitoring system consisting of a high-speed CCD camera, a pyrometer, and an infrared camera was used to analyze the mass- and heat-transfer in the cladding process. The particle transport in flight was viewed by a high-speed CCD camera; the interaction between powder flow and laser beam was observed by an infrared camera; and the thermal behavior of the molten pool was recorded by the pyrometer and the infrared camera. The effects of the processing parameters on the laser attenuation, particle heating and clad properties were investigated based on the obtained signals. The optical monitoring method improved the understanding about mutual interrelated phenomena in the cladding process.

  17. Helicity of circular polarized light backscattered from biological tissues influenced by optical clearing

    Science.gov (United States)

    Avci, E.; Macdonald, C. M.; Meglinski, I.

    2012-03-01

    An increasingly popular area of interest in biomedical diagnostics is the high sensitivity of scattered polarized light to subtle alterations in tissue morphology. Insight in to these interactions has lead to the development of real time non-invasive diagnostic and therapy methods, and will continue to do so, improving both the detection of diseases, and treatment responses in early stages. Here, the fundamental properties of circular polarized light, and its application to observe morphologic changes in biological tissues has been studied. The optical properties of biological tissues have been altered with the use of optical clearing agents and the polarization state of their scattered light analyzed. Following these observations, research into the feasibility of distinguishing changes in optical parameters of the media has been carried out. The results showed that using the specific polarimetry system, alterations to the phantom medium and biological tissues were resolvable, furthermore a particular dependence on the anisotropy of the scattering medium was found. This method provides a good foundation for future work implementing non-invasive diagnostic techniques for early disease detection, as many forms of cancerous growths alter the scattering anisotropy of the affected tissue.

  18. Fast, high-fidelity, all-optical and dynamically-controlled polarization gate using room-temperature atomic vapor

    Science.gov (United States)

    Li, Runbing; Zhu, Chengjie; Deng, L.; Hagley, E. W.

    2014-10-01

    We demonstrate a fast, all-optical polarization gate in a room-temperature atomic medium. Using a Polarization-Selective-Kerr-Phase-Shift (PSKPS) technique, we selectively write a π phase shift to one circularly-polarized component of a linearly-polarized input signal field. The output signal field maintains its original strength but acquires a 90° linear polarization rotation, demonstrating fast, high-fidelity, dynamically-controlled polarization gate operation. The intensity of the polarization-switching field used in this PKSPK-based polarization gate operation is only 2 mW/cm2, which would be equivalent to 0.5 nW of light power (λ = 800 nm) confined in a typical commercial photonic hollow-core fiber. This development opens a realm of possibilities for potential future extremely low light level telecommunication and information processing systems.

  19. Second harmonic spectroscopy to optically detect valley polarization in 2D materials

    Science.gov (United States)

    Hipolito, F.; Pereira, Vitor M.

    2017-06-01

    Valley polarization (VP), an induced imbalance in the populations of a multi-valley electronic system, allows emission of second harmonic (SH) light even in centrosymmetric crystals such as graphene. Whereas in systems such as MoS{{}2} or BN this adds to their intrinsic quadratic response, SH generation in a multi-valley inversion-symmetric crystal can provide a direct measure of valley polarization. By computing the nonlinear response and characterizing theoretically the respective SH as a function of polarization, temperature, electron density, and degree of VP, we demonstrate the possibility of disentangling and individually quantifying the intrinsic and valley contributions to the SH. A specific experimental setup is proposed to obtain direct quantitative information about the degree of VP and allow its remote mapping. This approach could prove useful for direct, contactless, real-space monitoring of valley injection and other applications of valley transport and valleytronics.

  20. Testing the existence of optical linear polarization in young brown dwarfs

    Science.gov (United States)

    Manjavacas, E.; Miles-Páez, P. A.; Zapatero-Osorio, M. R.; Goldman, B.; Buenzli, E.; Henning, T.; Pallé, E.; Fang, M.

    2017-07-01

    Linear polarization can be used as a probe of the existence of atmospheric condensates in ultracool dwarfs. Models predict that the observed linear polarization increases with the degree of oblateness, which is inversely proportional to the surface gravity. We aimed to test the existence of optical linear polarization in a sample of bright young brown dwarfs, with spectral types between M6 and L2, observable from the Calar Alto Observatory, and cataloged previously as low gravity objects using spectroscopy. Linear polarimetric images were collected in I and R band using CAFOS at the 2.2-m telescope in Calar Alto Observatory (Spain). The flux ratio method was employed to determine the linear polarization degrees. With a confidence of 3σ, our data indicate that all targets have a linear polarimetry degree in average below 0.69 per cent in the I band, and below 1.0 per cent in the R band, at the time they were observed. We detected significant (i.e. P/σ ≥ 3) linear polarization for the young M6 dwarf 2MASS J04221413+1530525 in the R band, with a degree of p* = 0.81 ± 0.17 per cent.

  1. Optical generation in an amplifying photonic crystal with an embedded nanocomposite polarizer

    Science.gov (United States)

    Dadoenkova, Yuliya; Glukhov, Igor; Moiseev, Sergey; Svetukhin, Viacheslav; Zhukov, Andrey; Zolotovskii, Igor

    2017-04-01

    We show the possibility of selective polarization generation in an amplifying photonic crystal structure via the use of an embedded film of a sub-wavelength thickness with uniformly oriented metallic elongated nanoparticles chaotically distributed in the volume of a semiconductor. Such nanocomposite polarizer presents a uniaxial crystal with different values of dielectric permittivity components along and perpendicular to the polar axis of the nanoparticles. Dispersion of the dielectric permittivity of the nanocomposite is defined by the concentration and shape factor of the nanoparticles. Wavelength dependence of imaginary part of the nanocomposite permittivity possesses a resonance behavior resulting from plasmon resonance in nanoparticles. We show that this allows, depending on the relative orientation of the nanocomposite anisotropy axis and the polarization direction of the light, to achieve the mode discrimination of the photonic structure in the vicinity of a resonance of one of the permittivity components, where the absorption of the nanocomposite layer is maximal. Also we vary the parameters of the nanocomposite polarizer to obtain the optimal conditions of optical generation at the given wavelength.

  2. Spectroscopic issues in optical polarization of 3He gas for Magnetic Resonance Imaging of human lungs

    Science.gov (United States)

    Dohnalik, T.; Głowacz, B.; Olejniczak, Z.; Pałasz, T.; Suchanek, M.; Wojna, A.

    2013-10-01

    The Magnetic Resonance Imaging (MRI) of human lungs for diagnostic purposes became possible by using nuclear spin hyperpolarized noble gases, such as 3He. One of the methods to polarize 3He is the Metastability Exchange Optical Pumping (MEOP), which up to now has been performed at low pressure of about 1 mbar and in low magnetic field below 0.1 T (standard conditions). The equilibrium nuclear polarization can reach up to 80%, but it is dramatically reduced during the subsequent gas compression to the atmospheric pressure that is necessary for the lungs examination. Further polarization losses occur during the transportation of the gas to the hospital scanner. It was shown recently that up to 50% polarization can be obtained at elevated pressure exceeding 20 mbar, by using magnetic field higher than 0.1 T (nonstandard conditions). Therefore, following the construction of the low-field MEOP polarizer located in the lab, a dedicated portable unit was developed, which uses the magnetic field of the 1.5 T MR medical scanner and works in the continuous-flow regime. The first in Poland MRI images of human lungs in vivo were obtained on the upgraded to 3He resonance frequency Siemens Sonata medical scanner. An evident improvement in the image quality was achieved when using the new technique. The paper shows how spectroscopic measurements of 3He carried out in various experimental conditions led both to useful practical results and to significant progress in understanding fundamental processes taking place during MEOP.

  3. Fiber optic shape sensing for monitoring of flexible structures

    Science.gov (United States)

    Lally, Evan M.; Reaves, Matt; Horrell, Emily; Klute, Sandra; Froggatt, Mark E.

    2012-04-01

    Recent advances in materials science have resulted in a proliferation of flexible structures for high-performance civil, mechanical, and aerospace applications. Large aspect-ratio aircraft wings, composite wind turbine blades, and suspension bridges are all designed to meet critical performance targets while adapting to dynamic loading conditions. By monitoring the distributed shape of a flexible component, fiber optic shape sensing technology has the potential to provide valuable data during design, testing, and operation of these smart structures. This work presents a demonstration of such an extended-range fiber optic shape sensing technology. Three-dimensional distributed shape and position sensing is demonstrated over a 30m length using a monolithic silica fiber with multiple optical cores. A novel, helicallywound geometry endows the fiber with the capability to convert distributed strain measurements, made using Optical Frequency-Domain Reflectometry (OFDR), to a measurement of curvature, twist, and 3D shape along its entire length. Laboratory testing of the extended-range shape sensing technology shows

  4. An Optical Fibre-Based Sensor for Respiratory Monitoring

    Directory of Open Access Journals (Sweden)

    Marek Krehel

    2014-07-01

    Full Text Available In this paper, a textile-based respiratory sensing system is presented. Highly flexible polymeric optical fibres (POFs that react to applied pressure were integrated into a carrier fabric to form a wearable sensing system. After the evaluation of different optical fibres, different setups were compared. To demonstrate the feasibility of such a wearable sensor, the setup featuring the best performance was placed on the human torso, and thus it was possible to measure the respiratory rate. Furthermore, we show that such a wearable system enables to keep track of the way of breathing (diaphragmatic, upper costal and mixed when the sensor is placed at different positions of the torso. A comparison of the results with the output of some commercial respiratory measurements devices confirmed the utility of such a monitoring device.

  5. Study of coherent optical fiber communication in electromagnetic field. 3. Measurement of transient state of polarization in actual OPGW caused by lightning; Coherent hikaritsushin eno denjikai no eikyo to taisaku. 3. Jitsu field no OPGW ni okeru rakurai ni yoru henpa hendo no sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Kurono, M.; Isawa, K.; Kuribata, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1995-03-01

    Coherent optical fiber communication method is effective for increase of transmission capacity of existing optical fiber. But it needs a control of polarization state of optical signal. Especially through OPGW (Optical fiber composite Ground Wire), the polarization state will be influenced by lightning. This report describes a field measurement of optical polarization characteristics in actual OPGW of Hokuriku electric company in the condition of lightning. Main results are follows; (1) In normal condition without lightning, the states of optical polarization have alternative fluctuations of 60Hz. (2) In lightning weather, the transients of optical polarization are detected 51 times in two half months. It is made clear that these transient states are due to lightning by checking the time of day with the time data of LLS (Lightning Location System) and with the time of power line trip. (3) By estimating the waves of polarization shift, the duration of transient is 2 - 5msec, the rise time is 50 - 200usec. and wave tail has damping oscillation of 2 - 5kHz. The maximum shift of polarization states on Poincare sphere is 165 degree, which means polarization changes almost opposite states. (4) By evaluating the locations of lightning with LLS data, the transient polarization shift is caused by lightning over 50 km from observed OPGW. And the short distance tends to the large fluctuation of polarization. This characteristics may have a possibility of application to lightning monitoring. 7 refs., 22 figs., 1 tab.

  6. Adhesive bond failure monitoring with triboluminescent optical fiber sensor

    Science.gov (United States)

    Shohag, Md Abu S.; Hammel, Emily C.; Olawale, David O.; Okoli, Okenwa O.

    2016-04-01

    One of the most severe damage modes in modern wind turbines is the failure of the adhesive joints in the trailing edge of the large composite blades. The geometrical shape of the blade and current manufacturing techniques make the trailing edge of the wind turbine blade more sensitive to damage. Failure to timely detect this damage type may result in catastrophic failures, expensive system downtime, and high repair costs. A novel sensing system called the In-situ Triboluminescent Optical Fiber (ITOF) sensor has been proposed for monitoring the initiation and propagation of disbonds in composite adhesive joints. The ITOF sensor combines the triboluminescent property of ZnS:Mn with the many desirable features of optical fiber to provide in-situ and distributed damage sensing in large composite structures like the wind blades. Unlike other sensor systems, the ITOF sensor does not require a power source at the sensing location or for transmitting damage-induced signals to the hub of the wind turbine. Composite parts will be fabricated and the ITOF integrated within the bondline to provide in-situ and real time damage sensing. Samples of the fabricated composite parts with integrated ITOF will be subjected to tensile and flexural loads, and the response from the integrated sensors will be monitored and analyzed to characterize the performance of the ITOF sensor as a debonding damage monitoring system. In addition, C-scan and optical microscopy will be employed to gain greater insights into the damage propagation behavior and the signals received from the ITOF sensors.

  7. Polar Mesospheric Clouds (PMCs) Observed by the Ozone Monitoring Instrument (OMI) on Aura

    Science.gov (United States)

    DeLand, Matthew T.; Shettle, Eric P.; Levelt, Pieternel F.; Kowalewski, Matthew G.

    2010-01-01

    Backscattered ultraviolet (BUV) instruments designed for measuring stratospheric ozone profiles have proven to be robust tools for observing polar mesospheric clouds (PMCs). These measurements are available for more than 30 years, and have been used to demonstrate the existence of long-term variations in PMC occurrence frequency and brightness. The Ozone Monitoring Instrument (OMI) on the EOS Aura satellite provides new and improved capabilities for PMC characterization. OMI uses smaller pixels than previous BUV instruments, which increases its ability to identify PMCs and discern more spatial structure, and its wide cross-track viewing swath provides full polar coverage up to 90 latitude every day in both hemispheres. This cross-track coverage allows the evolution of PMC regions to be followed over several consecutive orbits. Localized PMC variations determined from OMI measurements are consistent with coincident SBUV/2 measurements. Nine seasons of PMC observations from OMI are now available, and clearly demonstrate the advantages of these measurements for PMC analysis.

  8. Structural Health Monitoring of Composite Structures Using Fiber Optic Sensors

    Science.gov (United States)

    Whitaker, Anthony

    Structural health monitoring is the process of detecting damage to a structure, where damage can be characterized as changes to material/mechanical properties including but not limited to plastically deforming the material or the modification of connections. Fiber optic cables with fiber Bragg gratings have emerged as a reliable method of locally measuring strains within a structure. During the manufacturing of composite structures, the fiber optic cables can be embedded between lamina plies, allowing the ability to measure strain at discrete locations within the structure as opposed to electrical strain gauges, which must typically be applied to the surface only. The fiber optic sensors may be used to see if the local strain at the sensor location is beyond desired limits, or the array response may be mined to determine additional information about the loading applied to the structure. The work presented in this thesis is to present novel and potential applications of FBG sensors being used to assess the health of the structure. The first application is the dual application of the FBG sensor as a method to determine the strain around a bolt connection as well as the preload of the fastener using a single fiber optic sensor. The composite material around the bolted connections experience stress concentrations and are often the location of damage to the structure from operational cyclic loading over the lifetime of the structure. The degradation can occur more quickly if the fastener is insufficiently tight to transfer load properly. The second application is the ability to locate the impact location of a projectile with damaging and non-damaging energy. By locating and quantifying the damage, the sensor array provides the basis for a structural health monitoring system that has the potential to determine if the damage is extensive enough to replace, or if the part can be salvaged and retrofitted.

  9. Optical monitoring of silver-based transparent heat mirrors.

    Science.gov (United States)

    Lee, C C; Chen, S H; Jaing, C C

    1996-10-01

    Both three-layer (TiO(2)-Ag-TiO(2)) and five-layer (TiO(2)-Ag-TiO(2)-Ag-TiO(2)) heat mirrors with optimum transmission in the visible and good reflectance in the IR have been designed by admittance diagram techniques. The mirrors were fabricated successfully by optical monitoring. An interesting anomalous layer was found and explained, and its equivalent refractive index and thickness are 2.015 - i0.016 and 2.56 nm, respectively.

  10. Two-wave mixing of orthogonally polarized waves via anisotropic dynamic gratings in erbium-doped optical fiber

    Science.gov (United States)

    Stepanov, Serguei; Hernández, Eliseo; Plata, Marcos

    2005-06-01

    We report on observations of transient two-wave mixing (TWM) of orthogonally polarized waves counterpropagating through an Er-doped single-mode optical fiber. Experiments were performed in a 2-m-long moderately birefringent (with beat length ~2 cm) Er-doped fiber without optical pumping at the laser wavelength 1549 nm. The transient TWM signal observed for crossed linear polarizations of the recording waves oriented along two orthogonal birefringence axes of the fiber (i.e., for the interference pattern with spatially modulated state of light polarization only) proved to be approximately half of that observed for parallel polarizations. Direct measurements of the transient polarization hole-burning effect (i.e., that observed for fast switching of the input light linear polarization between two orthogonal orientations of the doped fiber birefringence axes) allow us to attribute formation of the corresponding anisotropic dynamic grating to this effect.

  11. Polarization Maintaining Fibre Loop Mirror for NRZ-to-PRZ Conversion in All-Optical Clock Recovery

    Institute of Scientific and Technical Information of China (English)

    XU Fan; ZHANG Xin-Liang; LIU Hai-Rong; LIU De-Ming; HUANG De-Xiu

    2006-01-01

    @@ We propose a novel configuration for clock extraction by converting the NRZ data into the PRZ data and by employing a polarization-maintaining fibre loop mirror (PMFLM) which is usually used as an optical comb filter.

  12. Design and analysis of polarization independent all-optical logic gates in silicon-on-insulator photonic crystal

    Science.gov (United States)

    Rani, Preeti; Kalra, Yogita; Sinha, R. K.

    2016-09-01

    In this paper, we have reported design and analysis of polarization independent all optical logic gates in silicon-on-insulator photonic crystal consisting of two dimensional honeycomb lattices with two different air holes exhibiting photonic band gap for both TE and TM mode in the optical communication window. The proposed structures perform as an AND optical logic gate and all the optical logic gates based on the phenomenon of interference. The response period and bit rate for TE and TM polarizations at a wavelength of 1.55 μm show improved results as reported earlier.

  13. An integrated approach to monitoring the calibration stability of operational dual-polarization radars

    Science.gov (United States)

    Vaccarono, Mattia; Bechini, Renzo; Chandrasekar, Chandra V.; Cremonini, Roberto; Cassardo, Claudio

    2016-11-01

    The stability of weather radar calibration is a mandatory aspect for quantitative applications, such as rainfall estimation, short-term weather prediction and initialization of numerical atmospheric and hydrological models. Over the years, calibration monitoring techniques based on external sources have been developed, specifically calibration using the Sun and calibration based on ground clutter returns. In this paper, these two techniques are integrated and complemented with a self-consistency procedure and an intercalibration technique. The aim of the integrated approach is to implement a robust method for online monitoring, able to detect significant changes in the radar calibration. The physical consistency of polarimetric radar observables is exploited using the self-consistency approach, based on the expected correspondence between dual-polarization power and phase measurements in rain. This technique allows a reference absolute value to be provided for the radar calibration, from which eventual deviations may be detected using the other procedures. In particular, the ground clutter calibration is implemented on both polarization channels (horizontal and vertical) for each radar scan, allowing the polarimetric variables to be monitored and hardware failures to promptly be recognized. The Sun calibration allows monitoring the calibration and sensitivity of the radar receiver, in addition to the antenna pointing accuracy. It is applied using observations collected during the standard operational scans but requires long integration times (several days) in order to accumulate a sufficient amount of useful data. Finally, an intercalibration technique is developed and performed to compare colocated measurements collected in rain by two radars in overlapping regions. The integrated approach is performed on the C-band weather radar network in northwestern Italy, during July-October 2014. The set of methods considered appears suitable to establish an online tool to

  14. Radiation-induced effects in polarization-maintaining optical fibers for interferometric gyroscope

    Institute of Scientific and Technical Information of China (English)

    Xueqin Wang; Chunxi Zhang; Jing Jin; Ningfang Song

    2011-01-01

    @@ Radiation-induced attenuation (RIA) in four types of polarization-maintaining optical fibers for interferometric fiberoptic gyroscope (IFOG) at 1310 nm is measured.The measurements are conducted during and after steady-state γ-ray irradiation using a 60Co source in order to observe significantly different RIA behavior and recovery kinetics.Mechanisms involving dopants and manufacturing process are introduced to analyze the RIA discrepancy as well as to guide the choice and hardening of optical fibers during the design of IFOG.Medium-accuracy IFOG using Ge-F-codoped fiber and pure silica core fiber can survive in the space radiation environment.%Radiation-induced attenuation (RIA) in four types of polarization-maintaining optical fibers for interferometric fiberoptic gyroscope (IFOG) at 1310 nm is measured. The measurements are conducted during and after steady-state γ-ray irradiation using a 60Co source in order to observe significantly different RIA behavior and recovery kinetics. Mechanisms involving dopants and manufacturing process are introduced to analyze the RIA discrepancy as well as to guide the choice and hardening of optical fibers during the design of IFOG. Medium-accuracy IFOG using Ge-F-codoped fiber and pure silica core fiber can survive in the space radiation environment.

  15. Monolithically integrated two-axis microgripper for polarization maintaining in optical fiber assembly.

    Science.gov (United States)

    Zhang, Jianbin; Lu, Kangkang; Chen, Weihai; Jiang, Jun; Chen, Wenjie

    2015-02-01

    Polarization maintaining optical fiber (PMOF) is a kind of special optical fiber that is designed to transmit the linearly polarized light. Unlike the general optical fiber, it is critical to conduct the rotational alignment between two PMOFs to guarantee the efficiency of light transmission. Until now, this alignment task still cannot be addressed with an efficient and economical way. Hence, we propose a monolithically integrated two-axis flexure-based microgripper that has the grasping and rubbing functions. To achieve a compact structure, the microgripper is designed with an asymmetric architecture. In this paper, the pseudo-rigid body model approach and finite element analysis are conducted to provide the essential guideline to accomplish the theoretical design. The prototype is fabricated by wire electrical discharge machining, with which two experiments are conducted to validate the performance of the microgripper. The experimental results demonstrate that the proposed microgripper can firmly grasp the optical fiber with the diameter of 250 μm and meanwhile can rub it more than 90° accurately and effectively, which indicate that it can satisfy the operating requirements well in the PMOF assembly.

  16. Bedside arterial blood gas monitoring system using fluorescent optical sensors

    Science.gov (United States)

    Bartnik, Daniel J.; Rymut, Russell A.

    1995-05-01

    We describe a bedside arterial blood gas (ABG) monitoring system which uses fluorescent optical sensors in the measurement of blood pH, PCO2 and PO2. The Point-of-Care Arterial Blood Gas Monitoring System consists of the SensiCathTM optical sensor unit manufactured by Optical Sensors Incorporated and the TramTM Critical Care Monitoring System with ABG Module manufactured by Marquette Electronics Incorporated. Current blood gas measurement techniques require a blood sample to be removed from the patient and transported to an electrochemical analyzer for analysis. The ABG system does not require removal of blood from the patient or transport of the sample. The sensor is added to the patient's existing arterial line. ABG measurements are made by drawing a small blood sample from the arterial line in sufficient quantity to ensure an undiluted sample at the sensor. Measurements of pH, PCO2 and PO2 are made within 60 seconds. The blood is then returned to the patient, the line flushed and results appear on the bedside monitor. The ABG system offers several advantages over traditional electrochemical analyzers. Since the arterial line remains closed during the blood sampling procedure the patient's risk of infection is reduced and the caregiver's exposure to blood is eliminated. The single-use, disposable sensor can be measure 100 blood samples over 72 hours after a single two-point calibration. Quality Assurance checks are also available and provide the caregiver the ability to assess system performance even after the sensor is patient attached. The ABG module integrates with an existing bedside monitoring system. This allows ABG results to appear on the same display as ECG, respiration, blood pressure, cardiac output, SpO2, and other clinical information. The small module takes up little space in the crowded intensive care unit. Performance studies compare the ABG system with an electrochemical blood gas analyzer. Study results demonstrated accurate and precise blood

  17. A fibre-optic oxygen sensor for monitoring human breathing.

    Science.gov (United States)

    Chen, Rongsheng; Formenti, Federico; Obeid, Andy; Hahn, Clive E W; Farmery, Andrew D

    2013-09-01

    The development and construction of a tapered-tip fibre-optic fluorescence based oxygen sensor is described. The sensor is suitable for fast and real-time monitoring of human breathing. The sensitivity and response time of the oxygen sensor were evaluated in vitro with a gas pressure chamber system, where oxygen partial pressure was rapidly changed between 5 and 15 kPa, and then in vivo in five healthy adult participants who synchronized their breathing to a metronome set at 10, 20, 30, 40, 50, and 60 breaths min(-1). A Datex Ultima medical gas analyser was used to monitor breathing rate as a comparator. The sensor's response time in vitro was less than 150 ms, which allows accurate continuous measurement of inspired and expired oxygen pressure. Measurements of breathing rate by means of our oxygen sensor and of the Datex Ultima were in strong agreement. The results demonstrate that the device can reliably resolve breathing rates up to 60 breaths min(-1), and that it is a suitable cost-effective alternative for monitoring breathing rates and end-tidal oxygen partial pressure in the clinical setting. The rapid response time of the sensor may allow its use for monitoring rapid breathing rates as occur in children and the newborn.

  18. Towards More Consistent Retrievals of Ice Cloud Optical and Microphysical Properties from Polar Orbiting Sensors

    Science.gov (United States)

    Baum, B. A.; Heymsfield, A.; Yang, P.

    2011-12-01

    Differences exist in the ice cloud optical thickness and effective particle size products provided by teams working with data from AVHRR (Advanced Very High Resolution Radiometer), MODIS (MODerate resolution Imaging Spectroradiometer), POLDER (Polarization and Directionality of the Earth Reflectance), Imaging Infrared Radiometer (IIR), and CALIOP (Cloud Aerosol LIdar with Orthogonal Polarization). The issue is in large part due to the assumed ice cloud single-scattering properties that each team uses in their retrievals. To gain insight into this problem, we are developing ice cloud single-scattering properties consistently from solar through far-infrared wavelengths by merging ice cloud microphysical data from in situ measurements with the very latest light scattering calculations for ice habits that include droxtals, solid/hollow columns, plates, solid/hollow bullet rosettes, aggregates of columns, and small/large aggregates of plates. The in-situ measurements are from a variety of field campaigns, including ARM-IOP, CRYSTAL-FACE, ACTIVE, SCOUT, MidCiX, pre-AVE, TC-4, and MACPEX. Among other advances, the light scattering calculations include the full phase matrix (i.e., polarization), incorporate a new treatment of forward scattering, and three levels of surface roughness from smooth to severely roughened. This talk will focus on improvements to our methodology for building both spectral and narrowband bulk scattering optical models appropriate for satellite imagers and hyperspectral infrared sensors. The new models provide a basis for investigating retrieval differences in the products from the sensor teams. We will discuss recent work towards improving the consistency of ice cloud microphysical/optical property retrievals between solar, polarimetric, and infrared retrieval approaches. It will be demonstrated that severely roughened ice particles correspond best in comparisons to polarization measurements. Further discussion will provide insight as to the

  19. A recent change in the optical and {\\gamma}-ray polarization of the Crab nebula and pulsar

    CERN Document Server

    Moran, Paul; Gouiffes, Christian; 3,; Laurent, Philipe; Hallinan, Gregg; Redfern, Michael; Shearer, Andrew

    2015-01-01

    We report on observations of the polarization of optical and {\\gamma}-ray photons from the Crab nebula and pulsar system using the Galway Astronomical Stokes Polarimeter (GASP), the Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) and the International Gamma-Ray Astrophysics Laboratory satellite (Integral). These, when combined with other optical polarization observations, suggest that the polarized optical emission and {\\gamma}-ray polarization changes in a similar manner. A change in the optical polarization angle has been observed by this work, from 109.5 \\pm 0.7\\deg in 2005 to 85.3 \\pm 1.4 \\deg in 2012. On the other hand, the {\\gamma}-ray polarization angle changed from 115 \\pm 11 \\deg in 2003-2007 to 80 \\pm 12 \\deg in 2012-2014. Strong flaring activities have been detected in the Crab nebula over the past few years by the high energy {\\gamma}-ray missions Agile and Fermi, and magnetic reconnection processes have been suggested to explain these observations. The change in the polarized optical...

  20. Large polarization-dependent exciton optical Stark effect in lead iodide perovskites

    Science.gov (United States)

    Yang, Ye; Yang, Mengjin; Zhu, Kai; Johnson, Justin C.; Berry, Joseph J.; van de Lagemaat, Jao; Beard, Matthew C.

    2016-08-01

    A strong interaction of a semiconductor with a below-bandgap laser pulse causes a blue-shift of the bandgap transition energy, known as the optical Stark effect. The energy shift persists only during the pulse duration with an instantaneous response time. The optical Stark effect has practical relevance for applications, including quantum information processing and communication, and passively mode-locked femtosecond lasers. Here we demonstrate that solution-processable lead-halide perovskites exhibit a large optical Stark effect that is easily resolved at room temperature resulting from the sharp excitonic feature near the bandedge. We also demonstrate that a polarized pump pulse selectively shifts one spin state producing a spin splitting of the degenerate excitonic states. Such selective spin manipulation is an important prerequisite for spintronic applications. Our result implies that such hybrid semiconductors may have great potential for optoelectronic applications beyond photovoltaics.

  1. Advances in seismic monitoring at Deception Island volcano (Antarctica since the International Polar Year

    Directory of Open Access Journals (Sweden)

    Enrique Carmona

    2014-06-01

    Full Text Available Deception Island is an active volcano located in the south Shetland Islands, Antarctica. It constitutes a natural laboratory to test geophysical instruments in extreme conditions, since they have to endure not only the Antarctic climate but also the volcanic environment. Deception is one of the most visited places in Antarctica, both by scientists and tourists, which emphasize the importance of volcano monitoring. Seismic monitoring has been going on since 1986 during austral summer surveys. The recorded data include volcano-tectonic earthquakes, long-period events and volcanic tremor, among others. The level of seismicity ranges from quiet periods to seismic crises (e.g. 1992-1993, 1999. Our group has been involved in volcano monitoring at Deception Island since 1994. Based on this experience, in recent years we have made the most of the opportunities of the International Polar Year 2007-2008 to introduce advances in seismic monitoring along four lines: (1 the improvement of the seismic network installed for seismic monitoring during the summer surveys; (2 the development and improvement of seismic arrays for the detection and characterization of seismo-volcanic signals; (3 the design of automated event recognition tools, to simplify the process of data interpretation; and (4 the deployment of permanent seismic stations. These advances help us to obtain more data of better quality, and therefore to improve our interpretation of the seismo-volcanic activity at Deception Island, which is a crucial step in terms of hazards assessment.

  2. QoS-aware precautionary performance monitoring for PCE-based coherent optical OFDM networks

    Institute of Scientific and Technical Information of China (English)

    Yueming Lu; Lianxing Hou

    2012-01-01

    A quality-of-service (QoS) aware scheme,called precautionary performance monitoring,is proposed to solve the optical impairments and congestion control in coherent optical orthogonal frequency division multiplexed (CO-OFDM) networks.The centralized path computation element (PCE) extensions based on the QoS level are applied to optical performance monitoring in this letter.

  3. Optically Monitoring Mineralization and Demineralization on Photoluminescent Bioactive Nanofibers.

    Science.gov (United States)

    Li, Xiang; Li, Yangyang; Chen, Xiaoyi; Li, Binbin; Gao, Bo; Ren, Zhaohui; Han, Gaorong; Mao, Chuanbin

    2016-04-05

    Bone regeneration and scaffold degradation do not usually follow the same rate, representing a daunting challenge in bone repair. Toward this end, we propose to use an external field such as light (in particular, a tissue-penetrating near-infrared light) to precisely monitor the degradation of the mineralized scaffold (demineralization) and the formation of apatite mineral (mineralization). Herein, CaTiO3:Yb(3+),Er(3+)@bioactive glass (CaTiO3:Yb(3+),Er(3+)@BG) nanofibers with upconversion (UC) photoluminescence (PL) were synthesized. Such nanofibers are biocompatible and can emit green and red light under 980 nm excitation. The UC PL intensity is quenched during the bone-like apatite formation on the surface of the nanofibers in simulated body fluid; more mineral formation on the nanofibers induces more rapid optical quenching of the UC PL. Furthermore, the quenched UC PL can recover back to its original magnitude when the apatite on the nanofibers is degraded. Our work suggests that it is possible to optically monitor the apatite mineralization and demineralization on the surface of nanofibers used in bone repair.

  4. Corrosion monitoring along infrastructures using distributed fiber optic sensing

    Science.gov (United States)

    Alhandawi, Khalil B.; Vahdati, Nader; Shiryayev, Oleg; Lawand, Lydia

    2016-04-01

    Pipeline Inspection Gauges (PIGs) are used for internal corrosion inspection of oil pipelines every 3-5 years. However, between inspection intervals, rapid corrosion may occur, potentially resulting in major accidents. The motivation behind this research project was to develop a safe distributed corrosion sensor placed inside oil pipelines continuously monitoring corrosion. The intrinsically safe nature of light provided motivation for researching fiber optic sensors as a solution. The sensing fiber's cladding features polymer plastic that is chemically sensitive to hydrocarbons within crude oil mixtures. A layer of metal, used in the oil pipeline's construction, is deposited on the polymer cladding, which upon corrosion, exposes the cladding to surrounding hydrocarbons. The hydrocarbon's interaction with the cladding locally increases the cladding's refractive index in the radial direction. Light intensity of a traveling pulse is reduced due to local reduction in the modal capacity which is interrogated by Optical Time Domain Reflectometery. Backscattered light is captured in real-time while using time delay to resolve location, allowing real-time spatial monitoring of environmental internal corrosion within pipelines spanning large distances. Step index theoretical solutions were used to calculate the power loss due changes in the intensity profile. The power loss is translated into an attenuation coefficient characterizing the expected OTDR trace which was verified against similar experimental results from the literature. A laboratory scale experiment is being developed to assess the validity of the model and the practicality of the solution.

  5. The RoboPol optical polarization survey of gamma-ray - loud blazars

    CERN Document Server

    Pavlidou, V; Myserlis, I; Blinov, D; King, O G; Papadakis, I; Tassis, K; Hovatta, T; Pazderska, B; Paleologou, E; Baloković, M; Feiler, R; Fuhrmann, L; Khodade, P; Kus, A; Kylafis, N; Modi, D; Panopoulou, G; Papamastorakis, I; Pazderski, E; Pearson, T J; Rajarshi, C; Ramaprakash, A; Reig, P; Readhead, A C S; Steiakaki, A; Zensus, J A

    2013-01-01

    We present first results from RoboPol, a novel-design optical polarimeter operating at the Skinakas Observatory in Crete. The data, taken during the May - June 2013 commissioning of the instrument, constitute a single-epoch linear polarization survey of a sample of gamma-ray - loud blazars, defined according to unbiased and objective selection criteria, easily reproducible in simulations, as well as a comparison sample of, otherwise similar, gamma-ray - quiet blazars. As such, the results of this survey are appropriate for both phenomenological population studies and for tests of theoretical population models. We have measured polarization fractions as low as $0.015$ down to $R$ magnitude of 17 and as low as $0.035$ down to 18 magnitude. The hypothesis that the polarization fractions of gamma-ray - loud and gamma-ray - quiet blazars are drawn from the same distribution is rejected at the $10^{-3}$ level. We therefore conclude that gamma-ray - loud and gamma-ray - quiet sources have different optical polarizat...

  6. Polarization and dynamical properties of VCSELs-based photonic neuron subject to optical pulse injection

    Science.gov (United States)

    Xiang, Shuiying; Wen, Aijun; Zhang, Hao; Li, Jiafu; Guo, Xingxing; Shang, Lei; Lin, Lin

    2016-11-01

    The polarization-resolved nonlinear dynamics of vertical-cavity surface-emitting lasers (VCSELs) subject to orthogonally polarized optical pulse injection are investigated numerically based on the spin flip model. By extensive numerical bifurcation analysis, the responses dynamics of photonic neuron based on VCSELs under the arrival of external stimuli of orthogonally polarized optical pulse injection are mainly discussed. It is found that, several neuron-like dynamics, such as phasic spiking of a single abrupt large amplitude pulse followed with or without subthreshold oscillation, and tonic spiking with multiple periodic pulses, are successfully reproduced in the numerical model of VCSELs. Besides, the effects of stimuli strength, pump current, frequency detuning, as well as the linewidth enhancement factor on the neuron-like response dynamics are examined carefully. The operating parameters ranges corresponding to different neuron-like dynamics are further identified. Thus, the numerical model and simulation results are very useful and interesting for the ultrafast brain-inspired neuromorphic photonics systems based on VCSELs.

  7. Optical cooling and trapping highly magnetic atoms: The benefits of a spontaneous spin polarization

    CERN Document Server

    Dreon, Davide; Bouazza, Chayma; Maineult, Wilfried; Dalibard, Jean; Nascimbene, Sylvain

    2016-01-01

    From the study of long-range-interacting systems to the simulation of gauge fields, open-shell Lanthanide atoms with their large magnetic moment and narrow optical transitions open novel directions in the field of ultracold quantum gases. As for other atomic species, the magneto-optical trap (MOT) is the working horse of experiments but its operation is challenging, due to the large electronic spin of the atoms. Here we present an experimental study of narrow-line Dysprosium MOTs. We show that the combination of radiation pressure and gravitational forces leads to a spontaneous polarization of the electronic spin. The spin composition is measured using a Stern-Gerlach separation of spin levels, revealing that the gas becomes almost fully spin-polarized for large laser frequency detunings. In this regime, we reach the optimal operation of the MOT, with samples of typically $3\\times 10^8$ atoms at a temperature of 20$\\,\\mu$K. The spin polarization reduces the complexity of the radiative cooling description, whi...

  8. Development of Ribbon Fiber Type Multi-Channel Power Level Monitor with Low-Insertion/Polarization Loss

    Institute of Scientific and Technical Information of China (English)

    Maki; Inai; Akira; Haraguchi; Takeo; Komiya; Kiyotaka; Murashima; Takashi; Sasaki; Kazuhito; Saitoh

    2003-01-01

    We would like to propose a new in-line multi-channel power level monitor, which is applicable as tap-monitor for multi-channel WDM signals. Its ribbon fiber structure has far exceeded PLC performance and realized compact-size and lower insertion/polarization dependent loss.

  9. Optical fibre biosensors using enzymatic transducers to monitor glucose

    Science.gov (United States)

    Scully, P. J.; Betancor, L.; Bolyo, J.; Dzyadevych, S.; Guisan, J. M.; Fernández-Lafuente, R.; Jaffrezic-Renault, N.; Kuncová, G.; Matejec, V.; O'Kennedy, B.; Podrazky, O.; Rose, K.; Sasek, L.; Young, J. S.

    2007-10-01

    The construction and performance of a novel enzyme based optical sensor for in situ continuous monitoring of glucose in biotechnological production processes is presented. Sensitive optical coatings are formed from inorganic-organic hybrid polymers (ORMOCER®sORMOCER®: Trademark of Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. in Germany.) combined with a flurophore (ruthenium complex) and an enzyme, and applied to lenses, declad polymer optical fibre (POF) and polymer clad silica fibre (PCS). The enzyme, glucose oxidase, catalyzes oxidization of glucose to gluconic acid by depleting oxygen. Oxygen consumption is determined by measuring the fluorescence lifetime of metal organic ruthenium complexes which are quenched by oxygen. The coatings developed were designed to adhere to glass and polymer surfaces, to be compatible with enzymes and ruthenium complexes, and were demonstrated both as double- and single-layer structures. The sensor response to gaseous oxygen, dissolved oxygen and dissolved glucose was measured via fluorescence lifetime changes. A best detection limit of 0.5% (vol) has been determined for gaseous O2 with selected ORMOCER® sensing layers. Glucose concentrations were measured to a detection limit of 0.1 mmol L-1 over a range up to 30 mmol L-1. The sensor was usable for 30 days in a bioreactor. The opto-electronic instrumentation and performance in laboratory bioreactors and in an industrial reactor are evaluated.

  10. Increasing the pump-up rate to polarize 3He gas using spin-exchange optical pumping method

    Science.gov (United States)

    Lee, Wai Tung; Tong, Xin; Rich, Dennis; Liu, Yun; Fleenor, Michael; Ismaili, Akbar; Pierce, Joshua; Hagen, Mark; Dadras, Jonny; Robertson, J. Lee

    2009-09-01

    In recent years, polarized 3He gas has increasingly been used as neutron polarizers and polarization analyzers. Two of the leading methods to polarize the 3He gas are the spin-exchange optical pumping (SEOP) method and the meta-stable exchange optical pumping (MEOP) method. At present, the SEOP setup is comparatively compact due to the fact that it does not require the sophisticated compressor system used in the MEOP method. The temperature and the laser power available determine the speed, at which the SEOP method polarizes the 3He gas. For the quantity of gas typically used in neutron scattering work, this speed is independent of the quantity of the gas required, whereas the polarizing time using the MEOP method is proportional to the quantity of gas required. Currently, using the SEOP method to polarize several bar-liters of 3He to 70% polarization would require 20-40 h. This is an order of magnitude longer than the MEOP method for the same quantity of gas and polarization. It would therefore be advantageous to speed up the SEOP process. In this article, we analyze the requirements for temperature, laser power, and the type of alkali used in order to shorten the time required to polarize 3He gas using the SEOP method.

  11. Monitoring of Tumor Response to Cisplatin Using Optical Spectroscopy

    Science.gov (United States)

    Spliethoff, Jarich W.; Evers, Daniel J.; Jaspers, Janneke E.; Hendriks, Benno H.W.; Rottenberg, Sven; Ruers, Theo J.M.

    2014-01-01

    INTRODUCTION: Anatomic imaging alone is often inadequate for tuning systemic treatment for individual tumor response. Optically based techniques could potentially contribute to fast and objective response monitoring in personalized cancer therapy. In the present study, we evaluated the feasibility of dual-modality diffuse reflectance spectroscopy–autofluorescence spectroscopy (DRS-AFS) to monitor the effects of systemic treatment in a mouse model for hereditary breast cancer. METHODS: Brca1−/−; p53−/− mammary tumors were grown in 36 mice, half of which were treated with a single dose of cisplatin. Changes in the tumor physiology and morphology were measured for a period of 1 week using dual-modality DRS-AFS. Liver and muscle tissues were also measured to distinguish tumor-specific alterations from systemic changes. Model-based analyses were used to derive different optical parameters like the scattering and absorption coefficients, as well as sources of intrinsic fluorescence. Histopathologic analysis was performed for cross-validation with trends in optically based parameters. RESULTS: Treated tumors showed a significant decrease in Mie-scattering slope and Mie-to-total scattering fraction and an increase in both fat volume fraction and tissue oxygenation after 2 days of follow-up. Additionally, significant tumor-specific changes in the fluorescence spectra were seen. These longitudinal trends were consistent with changes observed in the histopathologic analysis, such as vital tumor content and formation of fibrosis. CONCLUSIONS: This study demonstrates that dual-modality DRS-AFS provides quantitative functional information that corresponds well with the degree of pathologic response. DRS-AFS, in conjunction with other imaging modalities, could be used to optimize systemic cancer treatment on the basis of early individual tumor response. PMID:24726234

  12. Simultaneous chromatic dispersion, polarization-mode-dispersion and OSNR monitoring at 40Gbit/s.

    Science.gov (United States)

    Baker-Meflah, Lamia; Thomsen, Benn; Mitchell, John; Bayvel, Polina

    2008-09-29

    A novel method for independent and simultaneous monitoring of chromatic dispersion (CD), first-order PMD and OSNR in 40Gbit/s systems is proposed and demonstrated. This is performed using in-band tone monitoring of 5GHz, optically down-converted to a low intermediate-frequency (IF) of 10kHz. The measurement provides a large monitoring range with good accuracies for CD (4742+/-100ps/nm), differential group delay (DGD) (200+/-4ps) and OSNR (23+/-1dB), independently of the bit-rate. In addition, the use of electro-absorption modulators (EAM) for the simultaneous down-conversion of all channels and the use of low-speed detectors makes it cost effective for multi-channel operation.

  13. Simultaneously improving optical absorption of both transverse-electric polarized and transverse-magnetic polarized light for organic solar cells with Ag grating used as transparent electrode

    Directory of Open Access Journals (Sweden)

    Yongbing Long

    2014-08-01

    Full Text Available Theoretical simulations are performed to investigate optical performance of organic solar cells with Ag grating electrode. It is demonstrated that optical absorption for both transverse-electric (TE polarized and transverse-magnetic(TM polarized light is simultaneously improved when compared with that for the device without the Ag grating. The improvement is respectively attributed to the resonance and the surface plasmon polaritons within the device. After an additional WO3 layer is capped on the Ag grating, absorption of TE-polarized light is further improved due to resonance of double microcavities within the device, and absorption of TM-polarized light is improved by the combined effects of the microcavity resonance and the surface plasmon polaritons. Correspondingly, the short current density for randomly polarized light is improved by 18.1% from that of the device without the Ag grating. Finally, it is demonstrated that high transmission may not be an essential prerequisite for metallic gratings when they are used as transparent electrode since absorption loss caused by low transmission can be compensated by using a capping layer to optimize optical resonance of the WMC structure within the device.

  14. Optical CDMA with Embedded Spectral-Polarization Coding over Double Balanced Differential-Detector

    Science.gov (United States)

    Huang, Jen-Fa; Yen, Chih-Ta; Chen, Bo-Hau

    A spectral-polarization coding (SPC) optical code-division multiple-access (OCDMA) configuration structured over arrayed-waveguide grating (AWG) router is proposed. The polarization-division double balanced detector is adopted to execute difference detection and enhances system performance. The signal-to-noise ratio (SNR) is derived by taking the effect of PIIN into account. The result indicates that there would be up to 9-dB SNR improvement than the conventional spectral-amplitude coding (SAC) structures with Walsh-Hadamard codes. Mathematical deriving results of the SNR demonstrate the system embedded with the orthogonal state of polarization (SOP) will suppress effectively phase-induced intensity noise (PIIN). In addition, we will analyze the relations about bit error rate (BER) vs. the number of active users under the different encoding schemes and compare them with our proposed scheme. The BER vs. the effective power under the different encoding scheme with the same number of simultaneous active user conditions are also revealed. Finally, the polarization-matched factor and the difference between simulated and experimental values are discussed.

  15. Characterization of dentin, enamel, and carious lesions by a polarization-sensitive optical coherence tomography system

    Science.gov (United States)

    Chen, Yueli; Otis, Linda; Piao, Daqing; Zhu, Quing

    2005-04-01

    Enamel and dentin are the primary components of human teeth. Both of them have a strong polarization effect. We designed a polarization-sensitive optical coherence tomography (PSOCT) system to study the spatially resolved scattering and polarization phenomena of teeth. The system is constructed in free space to avoid the complexity of polarization control in fiber-based PSOCT. The structural features of enamel were evaluated in five human teeth that had no visible evidence of caries. The teeth were subsequently sectioned in mesial distal orientation and coronal orientation. Then the structural aspects of dentin were evaluated. OCT images were made of the mantel dentin near the dentin-enamel junction. Five teeth with interproximal and occlusal caries were also studied. With two channel and phase-retardation images, PSOCT provided better functional contrast and more detailed structural information than conventional OCT. For a better description of the measured PSOCT data, we classify these features by two types, i.e., the local textural features and the global structural features. This study indicates that PSOCT has the potential to be a powerful tool for research of dental formation and caries diagnosis.

  16. Optical Coherence Tomography and Optical Coherence Tomography Angiography in Monitoring Coats’ Disease

    Directory of Open Access Journals (Sweden)

    Wojciech Hautz

    2017-01-01

    Full Text Available Purpose. The aim of this study was to evaluate the usefulness of optical coherence tomography (OCT and optical coherence tomography angiography (OCTA in monitoring pediatric patients with Coats’ disease. Material and Methods. This retrospective study included 9 Caucasian patients receiving treatment for Coats’ disease at the Children’s Memorial Health Institute Ophthalmology Department between December 2014 and May 2016. The course of the disease was monitored with OCTA in combination with OCT and fluorescein angiography (FA. Results. OCT B-scans obtained in all patients correlated with FA findings. Reliable OCTA images were obtained in 8 patients. In one patient, numerous artifacts due to poor visual acuity and retinal detachment confounded the interpretation of findings. Conclusions. OCTA and OCT, in combination with FA, are useful in Coats’ disease diagnostics and treatment monitoring. As noninvasive methods, OCT and OCTA may be performed more often than FA, which enable precise monitoring of the disease and making decisions as to its further treatment.

  17. Birefringence measurement in polarization-sensitive optical coherence tomography using differential-envelope detection method

    Science.gov (United States)

    Kuo, Wen-Chuan; Lin, Shey-Chien; Chuang, Chung-Yu

    2010-05-01

    In this research, we integrated two demodulating logarithmic amplifiers with one differential amplifier for use in a Mach-Zehnder interferometer so as to obtain a two-channel polarization-sensitive optical coherence tomography system. Birefringence signals can be acquired using this system along with a differential-envelope detection method. Because the two orthogonal polarizations are common-path propagation, common noise originating from background fluctuations or multiple scattering in turbid media can be reduced to improve the detection sensitivity and accuracy of birefringence measurement. Besides, this simple and effective technique is an analog detection method and is capable of providing high temporal response; it can also help obtain a high time-bandwidth product as compared to the conventional method of using a numerical method with a limited sampling rate. The feasibility of the proposed system is supported by theory and is also shown by performing experiments involving a human vessel, which is a highly scattering medium with weak birefringence.

  18. Optical Sensing of Polarization States Changes in Meat due to the Ageing

    Science.gov (United States)

    Tománek, Pavel; Mikláš, Jan; Abubaker, Hamed Mohamed; Grmela, Lubomír

    2010-11-01

    Food materials or biological materials display large compositional variations, inhomogeneities, and anisotropic structures. The biological tissues consist of cells which dimensions are bigger than a wavelength of visible light, therefore Mie scattering of transmitted and reflected light occurs and different polarization states arise. The meat industry needs reliable meat quality information throughout the production process in order to guarantee high-quality meat products for consumers. The minor importance is still given to the food quality control and inspection during processing operations or storing conditions. The paper presents a quite simple optical method allowing measure the freshness or ageing of products. The principle is to study temporal characteristics of polarization states of forward or backward scattered laser light in the samples in function of meat ageing.

  19. Meta-Optical Chirality and Emergent Eigen-polarization Modes via Plasmon Interactions

    Science.gov (United States)

    Moocarme, Matthew; Proscia, Nicholas V.; Vuong, Luat T.

    2017-02-01

    The response of an individual meta-atom is often generalized to explain the collective response of a metasurface in a manner that neglects the interactions between meta-atoms. Here, we study a metasurface composed of tilted achiral meta-atoms with no spatial variation of the unit cell that derives appreciable optical chirality solely from the asymmetric interactions between meta-atoms. The interactions between meta-atoms are considered to stem from the Lorentz force arising from the Larmor radiation of adjacent plasmonic resonators because their inclusion in a simple model accurately predicts the bonding/anti- bonding modes that are measured experimentally. We also experimentally observe the emergence of multiple polarization eigenmodes, among other polarization-dependent responses, which cannot be modeled with the conventional formalism of transmission matrices. Our results are vital to the precise characterization and design of metasurfaces.

  20. Post-selection free, integrated optical source of non-degenerate, polarization entangled photon pairs

    CERN Document Server

    Herrmann, Harald; Thomas, Abu; Poppe, Andreas; Sohler, Wolfgang; Silberhorn, Christine

    2013-01-01

    We present an integrated source of polarization entangled photon pairs in the telecom regime, which is based on type II-phasematched parametric down-conversion (PDC) in a Ti-indiffused waveguide in periodically poled lithium niobate. The domain grating -- consisting of an interlaced bi-periodic structure -- is engineered to provide simultaneous phase-matching of two PDC processes, and enables the direct generation of non-degenerate, polarization entangled photon pairs with a brightness of $B=7\\times10^3$ pairs/(s mW GHz). The spatial separation of the photon pairs is accomplished by a fiber-optical multiplexer facilitating a high compactness of the overall source. Visibilities exceeding 95% and a violation of the Bell inequality with $S=2.57\\pm0.06$ could be demonstrated.

  1. Modeling optical and UV polarization of AGNs III. From uniform-density to clumpy regions

    CERN Document Server

    Marin, F; Gaskell, C M

    2015-01-01

    A growing body of evidence suggests that part of, if not all, scattering regions of active galactic nuclei (AGNs) are clumpy. Hence. in this paper, we run radiative transfer models in the optical/UV for a variety of AGN reprocessing regions with different distributions of clumpy scattering media. We use the latest version of the Monte Carlo code STOKES presented in the first two papers of this series to model AGN reprocessing regions of increasing morphological complexity. We replace previously uniform-density media with up to thousands of constant-density clumps. We couple a continuum source to fragmented equatorial scattering regions, polar outflows, and toroidal, obscuring dust regions and investigate a wide range of geometries. We also consider different levels of fragmentation in each scattering region to evaluate importance of fragmentation for the net polarization of the AGN. We find that, in comparison with uniform-density models, equatorial distributions of gas and dust clouds result in grayer spectr...

  2. A measurement of the absolute neutron beam polarization produced by an optically pumped sup 3 He neutron spin filter

    CERN Document Server

    Rich, D R; Crawford, B E; Delheij, P P J; Espy, M A; Haseyama, T; Jones, G; Keith, C D; Knudson, J; Leuschner, M B; Masaike, A; Masuda, Y; Matsuda, Y; Penttilae, S I; Pomeroy, V R; Smith, D A; Snow, W M; Szymanski, J J; Stephenson, S L; Thompson, A K; Yuan, V

    2002-01-01

    The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. At the LANSCE pulsed neutron source we have measured the neutron beam polarization with an absolute accuracy of 0.3% in the neutron energy range from 40 meV to 10 eV using an optically pumped polarized sup 3 He spin filter and a relative transmission measurement technique. sup 3 He was polarized using the Rb spin-exchange method. We describe the measurement technique, present our results, and discuss some of the systematic effects associated with the method.

  3. Direction reversal of the optical spin torque on a Rayleigh absorptive sphere in vector Bessel polarized beams

    Science.gov (United States)

    Yang, Ruiping; Li, Renxian; Qin, Shitong; Ding, Chunying; Mitri, F. G.

    2017-02-01

    The effect of polarization on the optical spin torque (OST) exerted on an absorptive Rayleigh dielectric sphere by a vector Bessel beam is investigated using the dipole approximation method, with particular emphasis on the polarization of the plane wave component forming the beam. On the basis of the mathematical descriptions for the electric fields, which are derived using the angular spectrum decomposition method in plane waves, analytical formulas of the OST are established. The OSTs are numerically calculated, and the effects of polarization, beam-order, and half-cone angle are discussed in detail. Numerical results show that by choosing an appropriate polarization, order and half-cone angle, the transverse OST will manifest vortex-like behaviors, and the sphere will experience negative axial OSTs, i.e. OST sign reversal. Important applications in particle manipulation, rotation and handling using optical Bessel polarized beams would benefit from the results of the present investigation.

  4. Time-Delay Signature of Chaotic Vertical-Cavity Surface-Emitting Lasers with Polarization-Rotated Optical Feedback

    Institute of Scientific and Technical Information of China (English)

    XIANG Shui-Ying; PAN Wei; YAN Lian-Shan; LUO Bin; ZOU Xi-Hua; JIANG Ning; WEN Kun-Hua

    2011-01-01

    To quantitatively evaluate the time-delay (TD) signatures of chaotic signals generated by vertical-cavity surface-emitting lasers (VCSELs) with polarization-rotated optical feedback (PROF), we propose four cases of resolution coefficients R based on correlation functions. The resolution coefficient characteristics for the x-polarization (XP) mode, y-polarization (YP) mode and the total output are considered. The dependences of R on the feedback strength and feedback delay are discussed and compared carefully. The two-dimensional maps of R show that the TD signatures for the single polarization mode (I.e., XP or YP mode) are much more difficult to retrieve than those for the total output in the entire parameter space. Thus, by using single polarization mode as a chaotic carrier, the TD signatures are extremely difficult to be identified, which contributes a lot in the security-enhanced VCSELs-based chaotic optical communication systems.

  5. How well can we monitor cloud properties over polar regions in winter?

    Science.gov (United States)

    Ackerman, S. A.; Holz, R.; Frey, R.; Heidinger, A.

    2008-12-01

    found for non-polar daytime conditions while the poorest agreement is in polar regions. The poor agreement during the polar wintertime leaves the following questions: "How capable are passive observing systems in retrieving cloud properties over the winter poles for climate studies?" Recent advances in active remote sensing technology have provided satellite-based lidar and radar measurements that allow us to fully answer this question. A combined data set of CALIOP and MODIS measurements provides a new opportunity to evaluate passive sensor cloud property retrievals over the entire polar region. To facilitate the comparison, a computationally efficient and accurate collocation methodology has been developed by Nagel and Holz (2008). MODIS has several infrared channels, three of which closely match the observations of the historical AVHRR instrument, thus the MODIS can be used to explore the capability of the AVHRR data record. With the collocated MODIS and CALIOP retrievals, nearly instantaneous comparisons are compiled regionally over both poles and are used to quantify our uncertainty in monitoring cloud conditions over the winter poles.

  6. Rockslide deformation monitoring with fiber optic strain sensors

    Directory of Open Access Journals (Sweden)

    J. R. Moore

    2010-02-01

    Full Text Available With micro-strain resolution and the capability to sample at rates of 100 Hz and higher, fiber optic (FO strain sensors offer exciting new possibilities for in-situ landslide monitoring. Here we describe a new FO monitoring system based on long-gauge fiber Bragg grating sensors installed at the Randa Rockslide Laboratory in southern Switzerland. The new FO monitoring system can detect sub-micrometer scale deformations in both triggered-dynamic and continuous measurements. Two types of sensors have been installed: (1 fully embedded borehole sensors and (2 surface extensometers. Dynamic measurements are triggered by sensor deformation and recorded at 100 Hz, while continuous data are logged every 5 min. Deformation time series for all sensors show displacements consistent with previous monitoring. Accelerated shortening following installation of the borehole sensors is likely related to long-term shrinkage of the grout. A number of transient signals have been observed, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new insight into the deformation process. Accelerated surface crack opening in spring is shown to have a diurnal trend, which we attribute to the effect of snowmelt seeping into the crack void space and freezing at night to generate pressure on the crack walls. Controlled-source tests investigated the sensor response to dynamic inputs, which compared an independent measure of ground motion against the strain measured across a surface crack. Low frequency signals were comparable but the FO record suffered from aliasing, where undersampling of higher frequency signals generated spectral peaks not related to ground motion.

  7. Monitoring Bio-Optical Processes Using NPP-VIIRS and MODIS-Aqua Ocean Color Products

    Science.gov (United States)

    2013-01-01

    Same day ocean color products from the S-NPP and MODIS provide for a new capability to monitor changes in the bio - optical processes occurring in...coastal waters. The combined use of multiple looks per day from several sensors can be used to follow the water mass changes of bio -optical properties...day to resolve bio - optical processes. We examine how these changes in bio -optical properties can be monitored using the NPP and MODIS ocean color

  8. Optical reconfiguration and polarization control in semicontinuous gold films close to the percolation threshold

    DEFF Research Database (Denmark)

    Frydendahl, Christian; Repän, Taavi; Geisler, Mathias

    In this work we have studied the intrinsic and reconfigured optical properties of semi-continuous gold films, fabricated via a simple metal evaporation technique. We have prepared three films of nominal thicknesses 5, 6, and 7nm. After fabrication the films are illuminated in areas by scanning a fs......-loss spectroscopy (EELS) measurements and extensive finite-element simulations of our sample morphologies to better understand the origin of this polarization effect as well as the distribution of plasmonic resonances with and without laser writing....

  9. Characterization of dual-polarization LTE radio over a free-space optical turbulence channel.

    Science.gov (United States)

    Bohata, J; Zvanovec, S; Korinek, T; Mansour Abadi, M; Ghassemlooy, Z

    2015-08-10

    A dual polarization (DP) radio over a free-space optical (FSO) communication link using a long-term evolution (LTE) radio signal is proposed and analyzed under different turbulence channel conditions. Radio signal transmission over the DP FSO channel is experimentally verified by means of error vector magnitude (EVM) statistics. We demonstrate that such a system, employing a 64 quadrature amplitude modulation at the frequency bands of 800 MHz and 2.6 GHz, evinces reliability with LTE signal over the FSO channel is a potential solution for last-mile access or backbone networks, when using multiple-input multiple-output based DP signals.

  10. Mechanism of all-optical control of ferromagnetic multilayers with circularly polarized light

    CERN Document Server

    Medapalli, Rajasekhar; Kim, Dokyun; Quessab, Yassine; Monotoya, Sergio A; Kirilyuk, Andrei; Rasing, Theo; Kimel, Alexey V; Fullerton, Eric E

    2016-01-01

    Time-resolved imaging reveals that the helicity dependent all-optical switching (HD-AOS) of Co/Pt ferromagnetic multilayers proceeds by two stages. First one involves the helicity independent and stochastic nucleation of reversed magnetic domains. At the second stage circularly polarized light breaks the degeneracy between the magnetic domains and promotes the preferred direction of domain wall (DW) motion. The growth of the reversed domain from the nucleation cite, for a particular helicity, leads to full magnetic reversal. This study demonstrates a novel mechanism of HD-AOS mediated by the deterministic displacement of DWs.

  11. Optical code division multiple access secure communications systems with rapid reconfigurable polarization shift key user code

    Science.gov (United States)

    Gao, Kaiqiang; Wu, Chongqing; Sheng, Xinzhi; Shang, Chao; Liu, Lanlan; Wang, Jian

    2015-09-01

    An optical code division multiple access (OCDMA) secure communications system scheme with rapid reconfigurable polarization shift key (Pol-SK) bipolar user code is proposed and demonstrated. Compared to fix code OCDMA, by constantly changing the user code, the performance of anti-eavesdropping is greatly improved. The Pol-SK OCDMA experiment with a 10 Gchip/s user code and a 1.25 Gb/s user data of payload has been realized, which means this scheme has better tolerance and could be easily realized.

  12. Simple Linear Optical 'Binary Measurement Tree' for Single Photonic Polarization Qubit

    Institute of Scientific and Technical Information of China (English)

    HAN Yang; WU Wei; WU Chun-Wang; CHEN Ping-Xing; LI Cheng-Zu

    2009-01-01

    Positive-operator-value-measurement (POVM) is one of the essential components of quantum information process-ing (QIP). Recently a 'binary measurement tree' (BST) strategy (PRA 77, 052104) is suggested for implementing arbitrary POVM by sequential two-operator POVMs. We present a simple novel two-operator POVM module via linear optics, which is employed as block to construct a 'binary measurement tree' for implementing arbitrary POVM on single photonic polarization qubit. The total complexity of the experimental setup is significantly reduced in contrast to the previous works. As an example, we give the detailed settings of a well-known POVM.

  13. Automated detection of chorio-scleral interface using polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Duan, Lian; Yamanari, Masahiro; Yasuno, Yoshiaki

    2012-01-01

    A polarization sensitive optical coherence tomography based automated algorithm for segmentation of the chorio-scleral interface is presented. The algorithm employs a two-step segmentation approach. At first, local birefringence based segmentation with low precision is performed to roughly distinguish the choroid and sclera. Successively, a depth oriented slope fitting to phase retardation is applied in both the choroid and sclera. The interface is determined as the cross-point of the two phase retardation slope lines. The algorithm shows potential for functional, objective, and volumetric choroid thickness measurement.

  14. Imaging of human breast tissue using polarization sensitive optical coherence tomography

    Science.gov (United States)

    Verma, Y.; Gautam, M.; Divakar Rao, K.; Swami, M. K.; Gupta, P. K.

    2011-12-01

    We report a study on the use of polarization sensitive optical coherence tomography (PSOCT) for discriminating malignant (invasive ductal carcinoma), benign (fibroadenoma) and normal (adipocytes) breast tissue sites. The results show that while conventional OCT, that utilizes only the intensity of light back-scattered from tissue microstructures, is able to discriminate breast tissues as normal (adipocytes) and abnormal (malignant and benign) tissues, PS-OCT helps in discriminating between malignant and benign tissue sites also. The estimated values of birefringence obtained from the PSOCT imaging show that benign breast tissue samples have significantly higher birefringence as compared to the malignant tissue samples.

  15. Analytical Solutions of Temporal Evolution of Populations in Optically-Pumped Atoms with Circularly Polarized Light

    Directory of Open Access Journals (Sweden)

    Heung-Ryoul Noh

    2016-03-01

    Full Text Available We present an analytical calculation of temporal evolution of populations for optically pumped atoms under the influence of weak, circularly polarized light. The differential equations for the populations of magnetic sublevels in the excited state, derived from rate equations, are expressed in the form of inhomogeneous second-order differential equations with constant coefficients. We present a general method of analytically solving these differential equations, and obtain explicit analytical forms of the populations of the ground state at the lowest order in the saturation parameter. The obtained populations can be used to calculate lineshapes in various laser spectroscopies, considering transit time relaxation.

  16. Fabrication and characteristics of character1 shaped reduced diameter polarization-maintaining optical fiber

    Institute of Scientific and Technical Information of China (English)

    Jianxiang Wen; Letian Liang; Tianpeng Xiao; Xiaojun Xu; Hua Yu; Wu Su

    2006-01-01

    @@ A novel structure reducing diameter polarization maintaining optical fiber with high birefringence and strength is introduced.The fiber is fabricated through using modified chemical vapor deposition (MCVD) method,which is able to produce the optimum predicted character-1 shaped fiber structure.As a result,a low-loss fiber with beat length close to 2.0 mm at 1310 nm wavelength and extinction ratio approximately-25 dB has been produced.The process is both simple and reproducible.

  17. A modified split—step fourier method for optical pulse propagation with polarization mode dispersion

    Institute of Scientific and Technical Information of China (English)

    RaoMin; SunXiao-Han; ZhangMing-De

    2003-01-01

    A modified split-step Fourier method (SSFM) is presented to solve the coupled nonlinear Schroedinger equation (CNLS) that can be used to model high-speed pulse propagation in optical fibres with polarization mode dispersion (PMD). We compare our approach with the SSFM and demonstrate that our approach is much faster with no loss of pre-chirped RZ(CRZ) formats in the presence of high PMD through this approach. The simulation results show that CRZ pulses are the most tolerant to high PMD values and the extinct ratio has a great impact on the transmission performance.

  18. Non-invasive assessment of corneal crosslinking changes using polarization sensitive optical coherence tomography

    Science.gov (United States)

    Alonso-Caneiro, D.; Yamanari, M.; Fukuda, S.; Hoshi, S.; Nagase, S.; Oshika, T.; Yasuno, Y.; Collins, M.

    2013-03-01

    Collagen crosslinking (CXL) has shown promising results in the prevention of the progression of keratoconus and corneal ectasia. However, techniques for in vivo and in situ assessment of the treatment are limited. In this study, ex vivo porcine eyes were treated with a chemical CXL agent (glutaraldehyde), during which polarization sensitive optical coherence tomography (PS-OCT) recordings were acquired simultaneously to assess the sensitivity of the technique to assess changes in the cornea. The results obtained in this study suggest that PSOCT may be a suitable technique to measure CXL changes in situ and to assess the local changes in the treated region of the cornea.

  19. Optical and Micro-Structural Characterization of MBE Grown Indium Gallium Nitride Polar Quantum Dots

    KAUST Repository

    El Afandy, Rami

    2011-07-07

    Gallium nitride and related materials have ushered in scientific and technological breakthrough for lighting, mass data storage and high power electronic applications. These III-nitride materials have found their niche in blue light emitting diodes and blue laser diodes. Despite the current development, there are still technological problems that still impede the performance of such devices. Three-dimensional nanostructures are proposed to improve the electrical and thermal properties of III-nitride optical devices. This thesis consolidates the characterization results and unveils the unique physical properties of polar indium gallium nitride quantum dots grown by molecular beam epitaxy technique. In this thesis, a theoretical overview of the physical, structural and optical properties of polar III-nitrides quantum dots will be presented. Particular emphasis will be given to properties that distinguish truncated-pyramidal III-nitride quantum dots from other III-V semiconductor based quantum dots. The optical properties of indium gallium nitride quantum dots are mainly dominated by large polarization fields, as well as quantum confinement effects. Hence, the experimental investigations for such quantum dots require performing bandgap calculations taking into account the internal strain fields, polarization fields and confinement effects. The experiments conducted in this investigation involved the transmission electron microscopy and x-ray diffraction as well as photoluminescence spectroscopy. The analysis of the temperature dependence and excitation power dependence of the PL spectra sheds light on the carrier dynamics within the quantum dots, and its underlying wetting layer. A further analysis shows that indium gallium nitride quantum dots through three-dimensional confinements are able to prevent the electronic carriers from getting thermalized into defects which grants III-nitrides quantum dot based light emitting diodes superior thermally induced optical

  20. Experimental Adaptive Digital Performance Monitoring for Optical DP-QPSK Coherent Receiver

    DEFF Research Database (Denmark)

    Borkowski, Robert; Zhang, Xu; Zibar, Darko;

    2011-01-01

    We report on a successful experimental demonstration of a digital optical performance monitoring (OPM) yielding satisfactory estimation accuracy along with adaptive impairment equalization. No observable penalty is measured when equalizer is driven by monitoring module....

  1. Photothermal modification of optical microscope for noninvasive living cell monitoring

    Science.gov (United States)

    Lapotko, Dmitry; Romanovskaya, Tat'yana; Zharov, Vladimir P.

    2001-06-01

    Photothermal method was applied to improve sensing and imaging capabilities of a light microscope in cell studies. We describe the methods, technical details and testing results of cytometric application of Laser Photothermal Phase Microscope (LPPM). The merits of the proposed approach include living single cell monitoring capability, quantitative measurement of cell functional features through the use of cell natural chromophores as the sensors. Such intracellular sensors are activated by the laser pulse and transform an absorbed energy into the heat. The latter causes thermal and mechanical loads to a cell and its components. The second stage of the process includes the reaction of the cell as integral system or of its components to such loads. This reaction is caused by the changes of cell functional and structural state and includes alterations of cell optical properties. Both processes are monitored for a single cell non-invasively with probe laser beam. Pulsed phase contrast dual beam illumination scheme with acquisition of several laser images at different stages of cell-laser interaction was introduced. An acquired cell image is considered as spatially and temporally resolved cell response to non-specific load that is induced in a cell with a pump laser. This method eliminates any cell staining and allows to monitor cell viability and cell reaction to the environmental factors. Also LPPM offers further improvement of spatial and temporal resolution of optical microscope: with pulsed probe laser monitoring we can detect components with the size down to 50 nm and temporal resolution of 10 ns. In our set up the cell is pumped by pulsed laser at 532 nm, 10 ns , 0.01-0.4 mJ. The source of probe beam is a pulsed dye laser (630 nm, 10 nJ, 10 ns) which forms cell phase image. The results obtained with living cells such as drug impact control, single cell dosimetry, immune action of light on a cell demonstrate basic features of LPPM as the tool for the study of the

  2. Constraints on the optical polarization source in the luminous non-blazar quasar 3C 323.1 (PG 1545+210) from the photometric and polarimetric variability

    Science.gov (United States)

    Kokubo, Mitsuru

    2017-01-01

    We examine the optical photometric and polarimetric variability of the luminous type 1 non-blazar quasar 3C 323.1 (PG 1545+210). Two optical spectro-polarimetric measurements taken during the periods 1996-98 and 2003 combined with a V-band imaging polarimetric measurement taken in 2002 reveal that (1) as noted in the literature, the polarization of 3C 323.1 is confined only to the continuum emission, that is, the emission from the broad line region is unpolarized; (2) the polarized flux spectra show evidence of a time-variable broad absorption feature in the wavelength range of the Balmer continuum and other recombination lines; (3) weak variability in the polarization position angle (PA) of ˜ 4 deg over a time-scale of 4-6 years is observed; and (4) the V-band total flux and the polarized flux show highly correlated variability over a time-scale of one year. Taking the above-mentioned photometric and polarimetric variability properties and the results from previous studies into consideration, we propose a geometrical model for the polarization source in 3C 323.1, in which an equatorial absorbing region and an axi-asymmetric equatorial electron-scattering region are assumed to be located between the accretion disc and the broad line region. The scattering/absorbing regions can perhaps be attributed to the accretion disc wind or flared disc surface, but further polarimetric monitoring observations for 3C 323.1 and other quasars with continuum-confined polarization are needed to probe the true physical origins of these regions.

  3. Fiber Optic Thermo-Hygrometers for Soil Moisture Monitoring.

    Science.gov (United States)

    Leone, Marco; Principe, Sofia; Consales, Marco; Parente, Roberto; Laudati, Armando; Caliro, Stefano; Cutolo, Antonello; Cusano, Andrea

    2017-06-20

    This work deals with the fabrication, prototyping, and experimental validation of a fiber optic thermo-hygrometer-based soil moisture sensor, useful for rainfall-induced landslide prevention applications. In particular, we recently proposed a new generation of fiber Bragg grating (FBGs)-based soil moisture sensors for irrigation purposes. This device was realized by integrating, inside a customized aluminum protection package, a FBG thermo-hygrometer with a polymer micro-porous membrane. Here, we first verify the limitations, in terms of the volumetric water content (VWC) measuring range, of this first version of the soil moisture sensor for its exploitation in landslide prevention applications. Successively, we present the development, prototyping, and experimental validation of a novel, optimized version of a soil VWC sensor, still based on a FBG thermo-hygrometer, but able to reliably monitor, continuously and in real-time, VWC values up to 37% when buried in the soil.

  4. Fiber Optic Thermo-Hygrometers for Soil Moisture Monitoring

    Directory of Open Access Journals (Sweden)

    Marco Leone

    2017-06-01

    Full Text Available This work deals with the fabrication, prototyping, and experimental validation of a fiber optic thermo-hygrometer-based soil moisture sensor, useful for rainfall-induced landslide prevention applications. In particular, we recently proposed a new generation of fiber Bragg grating (FBGs-based soil moisture sensors for irrigation purposes. This device was realized by integrating, inside a customized aluminum protection package, a FBG thermo-hygrometer with a polymer micro-porous membrane. Here, we first verify the limitations, in terms of the volumetric water content (VWC measuring range, of this first version of the soil moisture sensor for its exploitation in landslide prevention applications. Successively, we present the development, prototyping, and experimental validation of a novel, optimized version of a soil VWC sensor, still based on a FBG thermo-hygrometer, but able to reliably monitor, continuously and in real-time, VWC values up to 37% when buried in the soil.

  5. Fiber Optic Thermal Health Monitoring of Aerospace Structures and Materials

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.; Allison, Sidney G.

    2009-01-01

    A new technique is presented for thermographic detection of flaws in materials and structures by performing temperature measurements with fiber Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of structures with subsurface defects or thickness variations. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. The data obtained from grating sensors were further analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with those from conventional thermography techniques. Limitations of the technique were investigated using both experimental and numerical simulation techniques. Methods for performing in-situ structural health monitoring are discussed.

  6. A method for monitoring enamel erosion using laser irradiated surfaces and optical coherence tomography.

    Science.gov (United States)

    Chan, Kenneth H; Tom, Henry; Darling, Cynthia L; Fried, Daniel

    2014-11-01

    Since optical coherence tomography (OCT) is well suited for measuring small dimensional changes on tooth surfaces, OCT has great potential for monitoring tooth erosion. Previous studies have shown that enamel areas ablated by a carbon dioxide laser manifested lower rates of erosion compared to the non-ablated areas. The purpose of this study was to develop a model to monitor erosion in vitro that could potentially be used in vivo. Thirteen bovine enamel blocks were used in this in vitro study. Each 10 mm × 2 mm block was partitioned into five regions, the central region was unprotected, the adjacent windows were irradiated by a CO2 laser operating at 9.3 µm with a fluence of 2.4 J/cm(2) , and the outermost windows were coated with acid resistant varnish. The samples were exposed to a pH cycling regimen that caused both erosion and subsurface demineralization for 2, 4 and 6 days. The surfaces were scanned using a time-domain polarization sensitive optical coherence tomography (PS-OCT) system and the degree of surface loss (erosion) and the integrated reflectivity with lesion depth was calculated for each window. There was a large and significant reduction in the depth of surface loss (erosion) and the severity of demineralization in the areas irradiated by the laser. Irradiation of the enamel surface with a pulsed carbon dioxide laser at sub-ablative intensities results in significant inhibition of erosion and demineralization under the acid challenge employed in this study. In addition, these results suggest that it may be feasible to modify regions of the enamel surface using the laser to serve as reference marks to monitor the rate of erosion in vivo. © 2014 Wiley Periodicals, Inc.

  7. Simultaneous magneto-optical trapping of lithium and ytterbium atoms towards production of ultracold polar molecules

    CERN Document Server

    Okano, M; Muramatsu, M; Doi, K; Uetake, S; Takasu, Y; Takahashi, Y

    2009-01-01

    We have successfully implemented the first simultaneous magneto-optical trapping (MOT) of lithium ($^6$Li) and ytterbium ($^{174}$Yb) atoms, towards production of ultracold polar molecules of LiYb. For this purpose, we developed the dual atomic oven which contains both atomic species as an atom source and successfully observed the spectra of the Li and Yb atoms in the atomic beams from the dual atomic oven. We constructed the vacuum chamber including the glass cell with the windows made of zinc selenium (ZnSe) for the CO$_2$ lasers, which are the useful light sources of optical trapping for evaporative and sympathetic cooling. Typical atom numbers and temperatures in the compressed MOT are 7$\\times10^3$ atoms, 640 $\\mu$K for $^6$Li, 7$\\times10^4$ atoms and 60 $\\mu$K for $^{174}$Yb, respectively.

  8. Optically-driven red blood cell rotor in linearly polarized laser tweezers

    Indian Academy of Sciences (India)

    Manas Khan; Samarendra K Mohanty; A K Sood

    2005-11-01

    We have constructed a dual trap optical tweezers set-up around an inverted microscope where both the traps can be independently controlled and manipulated in all the three dimensions. Here we report our observations on rotation of red blood cells (RBCs) in a linearly polarized optical trap. Red blood cells deform and become twisted in hypertonic phosphate buffer saline and when trapped, experience an unbalanced radiation pressure force. The torque generated from the unbalanced force causes the trapped RBC to rotate. Addition of Ca++ ions in the solution, keeping the osmolarity same, makes the cell membranes stiffer and the cells deform less. Thus the speed of rotation of the red blood cells can be controlled, as less deformation and in turn less asymmetry in shape produces less torque under the radiation pressure resulting in slower rotation at the same laser power.

  9. Optical vibration modes and electron-phonon interaction in ternary mixed crystals of polar semiconductors

    Institute of Scientific and Technical Information of China (English)

    Liang Xi-Xia; Ban Shi-Liang

    2004-01-01

    @@ Optical vibrations of the lattice and the electron-phonon interaction in polar ternary mixed crystals are studied in the framework of the continuum model of Born and Huang and the random-element-isodisplacement model. A normal-coordinate system to describe the optical vibration in ternary mixed crystals is correctly adopted to derive a new Frohlich-like Hamiltonian for the electron-phonon interaction including the unit-cell volume variation influence.The numerical results for the phonon modes, the electron-phonon coupling constants and the polaronic energies for several typical materials are obtained. It is verified that the nonlinearity of the electron-phonon coupling effects with the composition is essential and the unit-cell volume effects cannot be neglected for most ternary mixed crystals.

  10. Automated identification of basal cell carcinoma by polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Duan, Lian; Marvdashti, Tahereh; Lee, Alex; Tang, Jean Y.; Ellerbee, Audrey K.

    2014-01-01

    We report an automated classifier to detect the presence of basal cell carcinoma in images of mouse skin tissue samples acquired by polarization-sensitive optical coherence tomography (PS-OCT). The sensitivity and specificity of the classifier based on combined information of the scattering intensity and birefringence properties of the samples are significantly higher than when intensity or birefringence information are used alone. The combined information offers a sensitivity of 94.4% and specificity of 92.5%, compared to 78.2% and 82.2% for intensity-only information and 85.5% and 87.9% for birefringence-only information. These results demonstrate that analysis of the combination of complementary optical information obtained by PS-OCT has great potential for accurate skin cancer diagnosis. PMID:25360384

  11. Nonreciprocal phase shift caused by magnetic-thermal coupling of a polarization maintaining fiber optic gyroscope.

    Science.gov (United States)

    Zhang, Dengwei; Zhao, Yuxiang; Fu, Wenlan; Zhou, Wenqing; Liu, Cheng; Shu, Xiaowu; Che, Shuangliang

    2014-03-15

    A theory for nonreciprocal phase shift caused by cross coupling generated in a polarization maintaining (PM) fiber optic gyroscope (FOG) under the combined action of magnetic and temperature fields is proposed. The magnetic-thermal coupling in the FOG originates from the interaction of the magnetic field, fiber twist, birefringence caused by thermal stress, and the intrinsic and bending birefringence of the fiber. The cross coupling changes with temperature. When the PM fiber has a diameter of 250 μm, beat length of 3 mm, length of 500 m, twist rate of 1  rad/m, and optical source wavelength of 1310 nm, the maximum degree of magnetic-thermal coupling generated by a 1 mT radial magnetic field within the temperature range of -20°C  to 60°C is -5.47%.

  12. Facile synthesis of single-crystalline microwires based on anthracene derivative and their efficient optical waveguides and linearly polarized emission

    Science.gov (United States)

    Peng, Hong-Dan; Wang, Juan-Ye; Liu, Zheng-Hui; Pan, Ge-Bo

    2016-05-01

    The well-defined single-crystalline microwires of a solid-emissive organic functional molecule, 2-(anthracen-9-yl)-4, 5-diphenyl-1H-imidozole (ADPI) were successfully prepared by a facile solution process without the use of surfactant or additional templates. In addition, the optical loss coefficient is as low as 0.1 dB μm-1 for the as-prepared ADPI microwires, which is lower than most previous reported organic optical waveguides. Meanwhile, these microwires also show optically uniaxial properties as demonstrated by the linearly polarized emission, providing potentially orientation-sensitive applications as optical waveguides with low optical loss.

  13. Monitoring Pre-Stressed Composites Using Optical Fibre Sensors

    Directory of Open Access Journals (Sweden)

    Sriram Krishnamurthy

    2016-05-01

    Full Text Available Residual stresses in fibre reinforced composites can give rise to a number of undesired effects such as loss of dimensional stability and premature fracture. Hence, there is significant merit in developing processing techniques to mitigate the development of residual stresses. However, tracking and quantifying the development of these fabrication-induced stresses in real-time using conventional non-destructive techniques is not straightforward. This article reports on the design and evaluation of a technique for manufacturing pre-stressed composite panels from unidirectional E-glass/epoxy prepregs. Here, the magnitude of the applied pre-stress was monitored using an integrated load-cell. The pre-stressing rig was based on a flat-bed design which enabled autoclave-based processing. A method was developed to end-tab the laminated prepregs prior to pre-stressing. The development of process-induced residual strain was monitored in-situ using embedded optical fibre sensors. Surface-mounted electrical resistance strain gauges were used to measure the strain when the composite was unloaded from the pre-stressing rig at room temperature. Four pre-stress levels were applied prior to processing the laminated preforms in an autoclave. The results showed that the application of a pre-stress of 108 MPa to a unidirectional [0]16 E-glass/913 epoxy preform, reduced the residual strain in the composite from −600 µε (conventional processing without pre-stress to approximately zero. A good correlation was observed between the data obtained from the surface-mounted electrical resistance strain gauge and the embedded optical fibre sensors. In addition to “neutralising” the residual stresses, superior axial orientation of the reinforcement can be obtained from pre-stressed composites. A subsequent publication will highlight the consequences of pres-stressing on fibre alignment, the tensile, flexural, compressive and fatigue performance of unidirectional E

  14. Application research on hydraulic coke cutting monitoring system based on optical fiber sensing technology

    Science.gov (United States)

    Zhong, Dong; Tong, Xinglin

    2014-06-01

    With the development of the optical fiber sensing technology, the acoustic emission sensor has become one of the focal research topics. On the basis of studying the traditional hydraulic coke cutting monitoring system, the optical fiber acoustic emission sensor has been applied in the hydraulic coke cutting monitoring system for the first time, researching the monitoring signal of the optical fiber acoustic emission sensor in the system. The actual test results show that using the acoustic emission sensor in the hydraulic coke cutting monitoring system can get the real-time and accurate hydraulic coke cutting state and the effective realization of hydraulic coke cutting automatic monitoring in the Wuhan Branch of Sinopec.

  15. Spectral Induced Polarization (SIP) monitoring during Microbial Enhanced Oil Recovery (MEOR)

    Science.gov (United States)

    Heenan, J. W.; Ntarlagiannis, D.; Slater, L. D.

    2010-12-01

    Jeffrey Heenan, Dimitrios Ntarlagiannis, Lee Slater Department of Earth and Environmental Sciences, Rutgers University, Newark NJ Microbial Enhanced Oil Recovery (MEOR) is an established, cost effective, method for enhancing tertiary oil recovery. Although not commonly used for shallow heavy oils, it could be a viable alternative since it can offer sustainable economic recovery and minimal environmental impact. A critical component of successful MEOR treatments is accurate, real time monitoring of the biodegradation processes resulting from the injection of microbial communities into the formation; results of recent biogeophysical research suggest that minimally-invasive geophysical methods could significantly contribute to such monitoring efforts. Here we present results of laboratory experiments, to assess the sensitivity of the spectral induced polarization method (SIP) to MEOR treatments. We used heavy oil, obtained from a shallow oilfield in SW Missouri, to saturate three sand columns. We then followed common industry procedures,and used a commercially available microbial consortia, to treat the oil columns. The active MEOR experiments were performed in duplicate while a control column maintained similar conditions, without promoting microbial activity and oil degradation. We monitored the SIP signatures, between 0.001 Hz and 1000 Hz, for a period of six months. To support the geophysical measurements we also monitored common geochemical parameters, including pH, Eh and fluid conductivity, and collected weekly fluid samples from the outflow and inflow for further analysis; fluid samples were analyzed to confirm that microbes actively degraded the heavy oils in the column while destructive analysis of the solid materials was performed upon termination of the experiment. Preliminary analysis of the results suggests that SIP is sensitive to MEOR processes. In both inoculated columns we recorded an increase in the low frequency polarization with time; measureable

  16. Feasibility study of a single-shot 3D electron bunch shape monitor with an electro-optic sampling technique

    Directory of Open Access Journals (Sweden)

    Yuichi Okayasu

    2013-05-01

    Full Text Available We developed a three-dimensional electron bunch charge distribution (3D-BCD monitor with single-shot detection, and a spectral decoding based electro-optic (EO sampling technique for a nondestructive monitor enables real-time reconstruction of the three-dimensional distribution of a bunch charge. We realized three goals by simultaneously probing a number of Pockels EO crystals that surround the electron beam axis with hollow and radial polarized laser pulses. First, we performed a feasibility test as a simple case of a 3D-BCD monitor probing two ZnTe crystals as EO detectors installed on the opposite angle to the electron beam axis and confirmed that we simultaneously obtained both EO signals. Since the adopted hollow probe laser pulse is not only radially polarized but also temporally shifted azimuthally, some disorders in the radial polarization distribution of such a laser pulse were numerically analyzed with a plane-wave expansion method. Based on the above investigations, the 3D-BCD monitor is feasible both in experimental and numerical estimations. Furthermore, we previously developed a femtosecond response organic crystal as a Pockels EO detector and a broadband probe laser (≥350  nm in FWHM; the 3D-BCD monitor realizes 30- to 40-fs (FWHM temporal resolution. Eventually, the monitor is expected to be equipped in such advanced accelerators as XFEL to measure and adjust the electron bunch charge distribution in real time. The 3D-BCD measurement works as a critical tool to provide feedback to seeded FELs.

  17. Monitoring optical properties of the southwest tropical Pacific

    Science.gov (United States)

    Dupouy, Cécile; Savranski, Tatiana; Lefevre, Jérôme; Despinoy, Marc; Mangeas, Morgan; Fuchs, Rosalie; Faure, Vincent; Ouillon, Sylvain; Petit, Michel

    2010-10-01

    We present data collected as part of ValHyBio- VALidation HYperspectral of a BIOgeochemical model in the South Western Tropical Lagoon of New Caledonia, a PNTS-sponsored program dedicated to chlorophyll satellite imaging and validation as affected by bathymetry. The specific goals of ValHyBio are to: - examine time-dependent oceanic reflectance in relation to dynamic surface processes, - construct field/satellite reflectance-based chlorophyll models, - investigate the feasibility of inverting the model to yield surface chlorophyll and turbidity, - validate the biogeochemical model with field/satellite observations. In situ bio-optical parameters include absorption coefficients by CDOM and particles, Secchi disk depth, backscattering coefficient, pigment concentration, suspended matter concentration, and K_dPAR. They are measured every month at 5 stations, of contrasted bathymetry and bottom reflectance, as well as at a reference station situated 4 miles offshore, and on a station over coral reefs. Remote sensing reflectance is calculated from the absorption and backscattering coefficients and compared with satellite data. SeaWIFS and MODIS AQUA match-ups collected over the period 1997-2010 (ValHySat-VALidation HYperspectral SATellite database) are used. Satellite retrievals are examined as a function of bathymetry. The feasibility of a longterm monitoring program of optical water retrieval with satellite remote sensing technique is examined in the frame of the GOPS (South Pacific Integrated Observatory).

  18. High performance polarization-independent Quantum Dot Semiconductor Optical Amplifier with 22 dB fiber to fiber gain using Mode Propagation Tuning without additional polarization controller

    Science.gov (United States)

    Farmani, Ali; Farhang, Mahmoud; Sheikhi, Mohammad H.

    2017-08-01

    A detailed numerical investigation of polarization-independent quantum dot InAs/GaAs semiconductor optical amplifier (PIQS) based on a technique called mode propagation tuning (MPT) without the need for the polarization controller (PC) is reported, which can solve the limitation caused by polarization sensitivity in a semiconductor optical amplifier (SOA). Our calculations show that by a suitable tuning of the thickness of the active layer, only the TE0 and TM0 modes can propagate. Moreover, the gain saturation behavior of this SOA was measured at 1.55 μ m and found to be polarization-independent (PI). At active layer thickness of 1.7 μ m, the confinement factor was 0.75 and 0.7 for TE0 and TM0 modes, respectively, which leads to a gain difference up to 0.1 dB. The rate equations of the QD-SOA were also solved and a fiber to fiber gain of 22 dB was obtained. Additionally, a numerical simulation is presented which shows that the residual gain ripple and polarization sensitivity are sufficiently reduced when residual facet reflectivities of the SOA are in the range below 10-4 . In addition, the full-width at half-maximum of the horizontal and vertical far-field patterns (FFPs) are measured as 30° × 30°. The proposed structure can be used for logical applications.

  19. Optical monitoring and detection of spinal cord ischemia.

    Directory of Open Access Journals (Sweden)

    Rickson C Mesquita

    Full Text Available Spinal cord ischemia can lead to paralysis or paraparesis, but if detected early it may be amenable to treatment. Current methods use evoked potentials for detection of spinal cord ischemia, a decades old technology whose warning signs are indirect and significantly delayed from the onset of ischemia. Here we introduce and demonstrate a prototype fiber optic device that directly measures spinal cord blood flow and oxygenation. This technical advance in neurological monitoring promises a new standard of care for detection of spinal cord ischemia and the opportunity for early intervention. We demonstrate the probe in an adult Dorset sheep model. Both open and percutaneous approaches were evaluated during pharmacologic, physiological, and mechanical interventions designed to induce variations in spinal cord blood flow and oxygenation. The induced variations were rapidly and reproducibly detected, demonstrating direct measurement of spinal cord ischemia in real-time. In the future, this form of hemodynamic spinal cord diagnosis could significantly improve monitoring and management in a broad range of patients, including those undergoing thoracic and abdominal aortic revascularization, spine stabilization procedures for scoliosis and trauma, spinal cord tumor resection, and those requiring management of spinal cord injury in intensive care settings.

  20. All-optical reconfigurable multi-logic gates based on nonlinear polarization rotation effect in a single SOA

    Institute of Scientific and Technical Information of China (English)

    Lilin Yi; Weisheng Hu; Hao He; Yi Dong; Yaohui Jin; Weiqiang Sun

    2011-01-01

    We demonstrate an all-optical reconfigurable logic gate based on dominant nonlinear polarization rotation accompanied with cross-gain modulation effect in a singlc semiconductor optical amplifier (SOA). Five logic functions, including NOT, OR, NOR, AND, and NAND, are realized using 10-Gb/s on-off keying signals with flexible wavelength tunability. The operation principle is explained in detail. By adjusting polarization controllers, multiple logic functions corresponding to different input polarization states are separately achieved using a single SOA with high flexibility.%@@ We demonstrate an all-optical reconfigurable logic gate based on dominant nonlinear polarization rotation accompanied with cross-gain modulation effect in a single semiconductor optical amplifier (SOA).Five logic functions, including NOT, OR, NOR, AND, and NAND, are realized using 10-Gb/s on-off keying signals with flexible wavelength tunability.The operation principle is explained in detail.By adjusting polarization controllers, multiple logic functions corresponding to different input polarization states are separately achieved using a single SOA with high flexibility.