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Sample records for wavelength shifting wls

  1. Wavelength shifting films on multianode PMTs with UV-extended window for the CBM RICH detector

    Energy Technology Data Exchange (ETDEWEB)

    Adamczewski-Musch, J. [GSI Darmstadt (Germany); Becker, K.-H. [University Wuppertal (Germany); Belogurov, S. [ITEP Moscow (Russian Federation); Boldyreva, N. [PNPI Gatchina (Russian Federation); Chernogorov, A. [ITEP Moscow (Russian Federation); Deveaux, C. [University Gießen (Germany); Dobyrn, V. [PNPI Gatchina (Russian Federation); Dürr, M., E-mail: Michael.Duerr@ap.physik.uni-giessen.de [University Gießen (Germany); Eom, J. [Pusan National University (Korea, Republic of); Eschke, J. [GSI Darmstadt (Germany); Höhne, C. [University Gießen (Germany); Kampert, K.-H. [University Wuppertal (Germany); Kleipa, V. [GSI Darmstadt (Germany); Kochenda, L. [PNPI Gatchina (Russian Federation); Kolb, B. [GSI Darmstadt (Germany); Kopfer, J., E-mail: Jan.Kopfer@uni-wuppertal.de [University Wuppertal (Germany); Kravtsov, P. [PNPI Gatchina (Russian Federation); Lebedev, S.; Lebedeva, E. [University Gießen (Germany); Leonova, E. [PNPI Gatchina (Russian Federation); and others

    2014-12-01

    Electron identification in the Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) will be performed using a gaseous RICH detector. Due to the UV transparency of the CO{sub 2} radiator, a high photon detection efficiency of the PMTs in use at small wavelengths is favourable. The use of wavelength shifting (WLS) films aims at increasing the integral quantum efficiency of the photon sensors. WLS films absorb UV photons and re-emit photons at longer wavelengths where the quantum efficiency of common photocathodes is higher. As photon sensors, multianode PMTs (MAPMTs) with bialkali or superbialkali photocathodes and UV-extended windows are envisaged. We present quantum efficiency measurements with and without WLS coating for different types of MAPMTs as well as results from a beam test at the CERN PS. An increased photon yield was observed when using WLS films. In addition, we discuss the effect of WLS films on the spatial resolution of MAPMTs. - Highlights: • Wavelength shifting (WLS) films were applied on MAPMTs with UV-window. • WLS films considerably enhance MAPMT quantum efficiency in the UV range. • In-beam tests with a RICH detector show an enhanced total photon yield by approx. 20%. • Yield enhancement depends on the MAPMT window and photocathode materials. • No significant effect of WLS films on ring sharpness was detected.

  2. PMT signal increase using a wavelength shifting paint

    Energy Technology Data Exchange (ETDEWEB)

    Allada, K. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hurlbut, Ch. [Eljen Technology, Sweetwater, TX 79556 (United States); Ou, L.; Schmookler, B. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Shahinyan, A. [Yerevan Physics Institute, Yerevan (Armenia); Wojtsekhowski, B., E-mail: bogdanw@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

    2015-05-11

    We report a 1.65 times increase of the PMT signal and a simple procedure of application of a new wavelength shifting (WLS) paint for PMTs with non-UV-transparent windows. Samples of four different WLS paints, made from hydrocarbon polymers and organic fluors, were tested on a 5-in. PMT (ET 9390KB) using Cherenkov radiation produced in fused silica disks by {sup 106}Ru electrons on a ‘table-top’ setup. The best performing paint was employed on two different types of 5-in. PMTs (ET 9390KB and XP4572B), installed in atmospheric pressure CO{sub 2} gas Cherenkov detectors, and tested using GeV electrons.

  3. Progress on the WOM (Wavelength-shifting optical module) development for IceCube

    Energy Technology Data Exchange (ETDEWEB)

    Hebecker, Dustin [DESY Zeuthen (Germany)

    2015-07-01

    For ongoing studies for the extension of the IceCube neutrino observatory to low energies (PINGU) and high energies the noise rate of the optical modules should be decreased and the effective area increased in order to improve energy resolution and overall sensitivity. The WOM (Wavelength-shifting optical module) targets this points by expanding the capture area while decreasing the size of the PMT and thus decreasing the noise rate. Photons are first captured in an organic wavelength-shifting material (WLS) that is coated on light guiding material to guide the light to two smaller PMTs. This allows to achieve a very large collection area and reduces the noise to the order of 10 Hz in comparison to 600-800 Hz (IceCube DOM). The progress on the necessary WLS paint development and substrate selection will be presented. Also a brief status / outlook on the prototype assembly will be given.

  4. Performance study of wavelength shifting acrylic plastic for Cherenkov light detection

    Energy Technology Data Exchange (ETDEWEB)

    Beckford, B., E-mail: beckford@aps.org [American Physical Society, One Physics Ellipse, College Park, MD 20740 (United States); De la Puente, A. [TRIUMF Laboratory, 4004 Wesbrook Mall, Vancouver, BC, Canada V6T 2A3 (Canada); Fujii, Y.; Hashimoto, O.; Kaneta, M.; Kanda, H.; Maeda, K.; Matsumura, A.; Nakamura, S.N. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Perez, N.; Reinhold, J. [Department of Physics, Florida International University, Miami, FL 33199 (United States); Tang, L. [Department of Physics, Hampton University, Hampton, VA 23668 (United States); Tsukada, K. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

    2014-01-21

    The collection efficiency for Cherenkov light incident on a wavelength shifting plate (WLS) has been determined during a beam test at the Proton Synchrotron facility located in the National Laboratory for High Energy Physics (KEK), Tsukuba, Japan. The experiment was conducted in order to determine the detector's response to photoelectrons converted from photons produced by a fused silica radiator; this allows for an approximation of the detector's quality. The yield of the photoelectrons produced through internally generated Cherenkov light as well as light incident from the radiator was measured as a function of the momentum of the incident hadron beam. The yield is proportional to sin{sup 2}θ{sub c}, where θ{sub c} is the opening angle of the Cherenkov light created. Based on estimations and results from similar conducted tests, where the collection efficiency was roughly 39%, the experimental result was expected to be around 40% for internally produced light from the WLS. The results of the experiment determined the photon collection response efficiency of the WLS to be roughly 62% for photons created in a fused silica radiator and 41% for light created in the WLS.

  5. A single photon sensor employing wavelength-shifting and light-guiding technology

    Energy Technology Data Exchange (ETDEWEB)

    Schulte, Lukas; Voge, Markus; Boeser, Sebastian; Kowalski, Marek [Physikalisches Institut, Universitaet Bonn (Germany)

    2013-07-01

    In this work we describe a feasibility study of a novel type of single photon sensor that employs organic wavelength shifting materials (WLS) to capture photons and guide them to a PMT readout. Two different WLS materials, Saint Gobain BC-480 and BC-482A, have been tested as candidates for use in such a sensor. We address the photon detection efficiency, noise properties, time and spatial resolution, PMT readout, as well as some practical aspects relevant for the development and construction of a prototype sensor. Calculating the overall photon detection efficiency, we show that the effective photosensitive area of a prototype built with existing technology could easily exceed that of modules currently used e. g. in IceCube while having a dark noise rate up to two orders of magnitude smaller.

  6. 15 years of experience with quality control of WLS fibres for the ATLAS Tile Calorimeter

    CERN Document Server

    David, M; Maio, A; Pina, J; Tomé, B

    2007-01-01

    We describe a test bench to measure the optical properties of scintillating and Wavelength-Shifting fibers, called the Fibrometer. The accuracy, stability and reproducibility were assessed, and the quality control of WLS fibers for the upgrade of the STIC luminosity monitor at DELPHI and for the Tile calorimeter of ATLAS is reported.

  7. Measurement of gamma quantum interaction point in plastic scintillator with WLS strips

    Energy Technology Data Exchange (ETDEWEB)

    Smyrski, J., E-mail: smyrski@if.uj.edu.pl [Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, S. Łojasiewicza 11, 30-348 Cracow (Poland); Alfs, D.; Bednarski, T.; Białas, P.; Czerwiński, E.; Dulski, K.; Gajos, A.; Głowacz, B.; Gupta-Sharma, N. [Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, S. Łojasiewicza 11, 30-348 Cracow (Poland); Gorgol, M.; Jasińska, B. [Department of Nuclear Methods, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin (Poland); Kajetanowicz, M.; Kamińska, D.; Korcyl, G. [Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, S. Łojasiewicza 11, 30-348 Cracow (Poland); Kowalski, P. [Świerk Computing Centre, National Centre for Nuclear Research, 05-400 Otwock-Świerk (Poland); Krzemień, W. [High Energy Department, National Centre for Nuclear Research, 05-400 Otwock-Świerk (Poland); Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz. [Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, S. Łojasiewicza 11, 30-348 Cracow (Poland); and others

    2017-04-11

    The feasibility of measuring the aśxial coordinate of a gamma quantum interaction point in a plastic scintillator bar via the detection of scintillation photons escaping from the scintillator with an array of wavelength-shifting (WLS) strips is demonstrated. Using a test set-up comprising a BC-420 scintillator bar and an array of sixteen BC-482A WLS strips we achieved a spatial resolution of 5 mm (σ) for annihilation photons from a {sup 22}Na isotope. The studied method can be used to improve the spatial resolution of a plastic-scintillator-based PET scanner which is being developed by the J-PET collaboration.

  8. Dual-wavelength phase-shifting digital holography selectively extracting wavelength information from wavelength-multiplexed holograms.

    Science.gov (United States)

    Tahara, Tatsuki; Mori, Ryota; Kikunaga, Shuhei; Arai, Yasuhiko; Takaki, Yasuhiro

    2015-06-15

    Dual-wavelength phase-shifting digital holography that selectively extracts wavelength information from five wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves in multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Numerical results show the validity of the proposed technique. The proposed technique is also experimentally demonstrated.

  9. A readout system for the wavelength-shifting optical module

    Energy Technology Data Exchange (ETDEWEB)

    Foesig, Carl-Christian; Boeser, Sebastian [Johannes Gutenberg-Universitaet, Mainz (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    The success of IceCube and the plans for an IceCube-Gen2 stimulate the development of new photo sensors. The approach of the Wavelength-shifting Optical Module is to provide a device which has a low dark noise rate combined with a high detection efficiency. A small PMT is used to detect red shifted photons guided in a coated PMMA tube, originally emitted by a wavelength shifting coating that absorbs photons in the UV Region. We have studied several PMTs for their usability with the IceCube-Gen2 readout system. Relevant parameters are the pulse widths in relation to the bandwidth of the IceCube-Gen2 readout electronics and the dark noise rates.

  10. Study of polystyrene scintillators-WLS fiber elements and scintillating tile-WLS prototypes for New CHOD detector of CERN NA-62 experiment

    CERN Document Server

    Semenov, Vitaliy; Gorin, Aleksandr; Khudyakov, Aleksey; Rykalin, Vladimir; Yushchenko, Oleg

    2016-01-01

    We measured the light output and the time resolution of few sets comprised of polystyrene scintillator and wavelength shifting (WLS) fibers as readout. The samples of different thickness (7-30 mm) have been made in the shape of bricks and plates with the areas of 25×80, 108×134 and 108×268 of mm2. In addition to samples of “ordinary” scintillator with additions of 2% p- Terphenyl + 0.05% POPOP, the rapid ultraviolet scintillator with single 2% additive PBD was tested. For the light collection WLS-fibers BCF92, Y11 and scintillation fiber SCSF-78M as reemitting were checked. The fibers were glued into the grooves on the front surface of scintillators. As the photo detectors silicon photomultipliers (SiPM) produced by CPTA (Russia) and SensL (Ireland) were used. It is shown that the dependence of light output on the thickness of scintillator is nonlinear and close to the square root function, which is also confirmed by the calculations carried out by Monte Carlo. The measured value of a light output make...

  11. CBET Experiments with Wavelength Shifting at the Nike Laser

    Science.gov (United States)

    Weaver, James; McKenty, P.; Bates, J.; Myatt, J.; Shaw, J.; Obenschain, K.; Oh, J.; Kehne, D.; Obenschain, S.; Lehmberg, R. H.; Tsung, F.; Schmitt, A. J.; Serlin, V.

    2016-10-01

    Studies conducted at NRL during 2015 searched for cross-beam energy transport (CBET) in small-scale plastic targets with strong gradients in planar, cylindrical, and spherical geometries. The targets were irradiated by two widely separated beam arrays in a geometry similar to polar direct drive. Data from these shots will be presented that show a lack of a clear CBET signature even with wavelength shifting of one set of beams. This poster will discuss the next campaign being planned, in part, with modelling codes developed at LLE. The next experiments will use a target configuration optimized to create stronger SBS growth. The primary path under consideration is to increase scale lengths 5-10x over the previous study by using exploding foils or low density foams. In addition to simulations, the presentation will also discuss improvements to the diagnostic suite and laser operations; for example, a new set of etalons will be available for the next campaign that should double the range of wavelength shifting between the two beam arrays. Work supported by DoE/NNSA.

  12. Frequency domain phase retrieval of simultaneous multi-wavelength phase-shifting interferometry

    International Nuclear Information System (INIS)

    Yin, Zhenxing; Zhong, Liyun; Xu, Xiaofei; Zhang, Wangping; Lu, Xiaoxu; Tian, Jindong

    2016-01-01

    In simultaneous multi-wavelength phase-shifting interferometry, we propose a novel frequency domain phase retrieval (FDPR) algorithm. First, using only a one-time phase-shifting operation, a sequence of simultaneous multi-wavelength phase-shifting interferograms (SPSMWIs) are captured by a monochrome charge-coupled device. Second, by performing a Fourier transform for each pixel of SPSMWIs, the wrapped phases of each wavelength can be retrieved from the complex amplitude located in the spectral peak of each wavelength. Finally, the phase of the synthetic wavelength can be obtained by the subtraction between the wrapped phases of a single wavelength. In this study, the principle and the application condition of the proposed approach are discussed. Both the simulation and the experimental result demonstrate the simple and convenient performance of the proposed FDPR approach. (paper)

  13. Wavelength shifting reflector foils for liquid Ar scintillation light

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Manuel [Physik Institut, Universitaet Zuerich (Switzerland); Collaboration: GERDA-Collaboration

    2013-07-01

    Liquid argon is used as a scintillator in several present and upcoming experiments. In Gerda it is used as a coolant, shielding and will be instrumented to become an active veto in Phase II. Its scintillation light has a wavelength of 128 nm, that gets absorbed by quartz. In order to measure the light using photo multiplier tubes (PMT) for cryogenic temperatures which have a quartz window, it is converted to longer wavelength by coated reflector foils. The conversion efficiency and stability of several such coatings was optimized using VM2000 and Tetratex separately as reflector foils. The efficiency has been measured in a liquid Ar set up build especially for this purpose. It employs a 3'' low radioactivity PMT of type R11065-10 from Hamamatsu, the favorite photo sensor candidate to be used in Gerda.

  14. Performance and calibration of wave length shifting fibers for K2K SciBar detector

    International Nuclear Information System (INIS)

    Morita, Taichi

    2004-01-01

    The wave length shifting (WLS) fibers (Kuraray Y11 (200) MS) are used for light collection from scintillators in the SciBar detector. The performance of WLS fibers was measured before installation. Because the number of WLS fibers is about 15,000, it is necessary to make a system to measure attenuation length of WLS fibers efficiently. I will report the pre-calibration method for measurement and the performance of the WLS fibers in SciBar detector. (author)

  15. Enhanced UV light detection using wavelength-shifting properties of Silicon nanoparticles

    International Nuclear Information System (INIS)

    Magill, S.; Xie, J.; Nayfeh, M.; Fizari, M.; Malloy, J.; Maximenko, Y.; Yu, H.

    2015-01-01

    Detection of UV photons is becoming increasingly necessary with the use of noble gases and liquids in elementary particle experiments. Cerenkov light in crystals and glasses, scintillation light in neutrino, dark matter, and rare decay experiments all require sensitivity to UV photons. New sensor materials are needed that can directly detect UV photons and/or absorb UV photons and re-emit light in the visible range measurable by existing photosensors. It has been shown that silicon nanoparticles are sensitive to UV light in a wavelength range around ∼ 200 nm. UV light is absorbed and re-emitted at wavelengths in the visible range depending on the size of the nanoparticles. Initial tests of the wavelength-shifting properties of silicon nanoparticles are presented here that indicate by placing a film of nanoparticles in front of a standard visible-wavelength detecting photosensor, the response of the sensor is significantly enhanced at wavelengths < 320 nm

  16. Wavelength shift in a whispering gallery microdisk due to bacterial sensing: A theoretical approach

    Directory of Open Access Journals (Sweden)

    Hala Ghali

    2017-04-01

    Full Text Available Whispering gallery mode microcavities have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Binding of a biomolecule to the surface of a microresonator will increase its path length, leading to a shift in the resonance frequency according to the reactive sensing principle. In this paper, we develop a theoretical expression that will link the reactive shift to the bacteria and microdisk parameters and help quantify the number of bacteria that bind to the surface of a 200μm-diameter silica microdisk. Keywords: Optical microdisk, Wavelength shift, Bacterial sensing

  17. Correction of phase-shifting error in wavelength scanning digital holographic microscopy

    Science.gov (United States)

    Zhang, Xiaolei; Wang, Jie; Zhang, Xiangchao; Xu, Min; Zhang, Hao; Jiang, Xiangqian

    2018-05-01

    Digital holographic microscopy is a promising method for measuring complex micro-structures with high slopes. A quasi-common path interferometric apparatus is adopted to overcome environmental disturbances, and an acousto-optic tunable filter is used to obtain multi-wavelength holograms. However, the phase shifting error caused by the acousto-optic tunable filter reduces the measurement accuracy and, in turn, the reconstructed topographies are erroneous. In this paper, an accurate reconstruction approach is proposed. It corrects the phase-shifting errors by minimizing the difference between the ideal interferograms and the recorded ones. The restriction on the step number and uniformity of the phase shifting is relaxed in the interferometry, and the measurement accuracy for complex surfaces can also be improved. The universality and superiority of the proposed method are demonstrated by practical experiments and comparison to other measurement methods.

  18. Liquid argon scintillation detection utilizing wavelength-shifting plates and light guides

    Science.gov (United States)

    Howard, B.

    2018-02-01

    In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.

  19. Liquid Argon Scintillation Detection Utilizing Wavelength-Shifting Plates and Light Guides

    Energy Technology Data Exchange (ETDEWEB)

    Howard, B. [Indiana U.

    2018-02-06

    In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.

  20. Phase retrieval from the phase-shift moiré fringe patterns in simultaneous dual-wavelength interferometry

    Science.gov (United States)

    Cheng, Jinlong; Gao, Zhishan; Bie, Shuyou; Dou, Yimeng; Ni, Ruihu; Yuan, Qun

    2018-02-01

    Simultaneous dual-wavelength interferometry (SDWI) could extend the measured range of each single-wavelength interferometry. The moiré fringe generated in SDWI indirectly represents the information of the measured long synthetic-wavelength ({λ }{{S}}) phase, thus the phase demodulation is rather arduous. To address this issue, we present a method to convert the moiré fringe pattern into a synthetic-wavelength interferogram (moiré to synthetic-wavelength, MTS). After the square of the moiré fringe pattern in the MTS method, the additive moiré pattern is turned into a multiplicative one. And the synthetic-wavelength interferogram could be obtained by a low-pass filtering in spectrum of the multiplicative moiré fringe pattern. Therefore, when the dual-wavelength interferometer is implemented with the π/2 phase shift at {λ }{{S}}, a sequence of synthetic-wavelength phase-shift interferograms with π/2 phase shift could be obtained after the MTS method processing on the captured moiré fringe patterns. And then the synthetic-wavelength phase could be retrieved by the conventional phase-shift algorithm. Compared with other methods in SDWI, the proposed MTS approach could reduce the restriction of the phase shift and frame numbers for the adoption of the conventional phase-shift algorithm. Following, numerical simulations are executed to evaluate the performance of the MTS method in processing time, frames of interferograms and the phase shift error compensation. And the necessary linear carrier for MTS method is less than 0.11 times of the traditional dual-wavelength spatial-domain Fourier transform method. Finally, the deviations for MTS method in experiment are 0.97% for a step with the height of 7.8 μm and 1.11% for a Fresnel lens with the step height of 6.2328 μm.

  1. Photoelectron yields of scintillation counters with embedded wavelength-shifting fibers read out with silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Artikov, Akram; Baranov, Vladimir; Blazey, Gerald C.; Chen, Ningshun; Chokheli, Davit; Davydov, Yuri; Dukes, E. Craig; Dychkant, Alexsander; Ehrlich, Ralf; Francis, Kurt; Frank, M. J.; Glagolev, Vladimir; Group, Craig; Hansen, Sten; Magill, Stephen; Oksuzian, Yuri; Pla-Dalmau, Anna; Rubinov, Paul; Simonenko, Aleksandr; Song, Enhao; Stetzler, Steven; Wu, Yongyi; Uzunyan, Sergey; Zutshi, Vishnu

    2018-05-01

    Photoelectron yields of extruded scintillation counters with titanium dioxide coating and embedded wavelength shifting fibers read out by silicon photomultipliers have been measured at the Fermilab Test Beam Facility using 120\\,GeV protons. The yields were measured as a function of transverse, longitudinal, and angular positions for a variety of scintillator compositions and reflective coating mixtures, fiber diameters, and photosensor sizes. Timing performance was also studied. These studies were carried out by the Cosmic Ray Veto Group of the Mu2e collaboration as part of their R\\&D program.

  2. Photoelectron yields of scintillation counters with embedded wavelength-shifting fibers read out with silicon photomultipliers

    Science.gov (United States)

    Artikov, Akram; Baranov, Vladimir; Blazey, Gerald C.; Chen, Ningshun; Chokheli, Davit; Davydov, Yuri; Dukes, E. Craig; Dychkant, Alexsander; Ehrlich, Ralf; Francis, Kurt; Frank, M. J.; Glagolev, Vladimir; Group, Craig; Hansen, Sten; Magill, Stephen; Oksuzian, Yuri; Pla-Dalmau, Anna; Rubinov, Paul; Simonenko, Aleksandr; Song, Enhao; Stetzler, Steven; Wu, Yongyi; Uzunyan, Sergey; Zutshi, Vishnu

    2018-05-01

    Photoelectron yields of extruded scintillation counters with titanium dioxide coating and embedded wavelength shifting fibers read out by silicon photomultipliers have been measured at the Fermilab Test Beam Facility using 120 GeV protons. The yields were measured as a function of transverse, longitudinal, and angular positions for a variety of scintillator compositions, reflective coating mixtures, and fiber diameters. Timing performance was also studied. These studies were carried out by the Cosmic Ray Veto Group of the Mu2e collaboration as part of their R&D program.

  3. The response of wavelength shifting panels in large water Cherenkov systems

    International Nuclear Information System (INIS)

    Bakich, A.M.; Peak, L.S.

    1986-01-01

    This paper describes a series of tests performed with a panel Bicron wavelength shifting acrylic plastic (BC-480) coupled to an EMI 9623B photomultiplier tube. The aim was to effectively increase the cathode coverage and its sensitivity to incident Cherenkov radiation, so that such a system could be employed in a solar neutrino detector. Measurements of the uniformity and effective efficiency of the system have been made and compared with the results of various simulation runs. The effects of side mirrors, back reflector, water interface and possible shaping of the panel to enhance its response are also assessed. (orig.)

  4. Measurement of Cerenkov Radiation Induced by the Gamma-Rays of Co-60 Therapy Units Using Wavelength Shifting Fiber

    Directory of Open Access Journals (Sweden)

    Kyoung Won Jang

    2014-04-01

    Full Text Available In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%.

  5. An amplified coarse wavelength division multiplexing self-referencing sensor network based on phase-shifted FBGs in transmissive configuration

    International Nuclear Information System (INIS)

    Elosua, C; Perez-Herrera, R A; Lopez-Amo, M; Bariain, C; Garcia-Olcina, R; Sales, S; Capmany, J

    2009-01-01

    A new amplified CWDM (coarse wavelength division multiplexing) self-referencing sensor network using phase-shifted fibre Bragg gratings (PS-FBGs) is experimentally demonstrated in this work. The network uses the PS-FBGs to address intensity sensors in a transmissive configuration, obtaining simultaneously in reflection a wavelength encoded reference signal. In order to enable the remote operation of the sensors, we have introduced optical amplification at the interrogation header of the network, using highly doped erbium fibre

  6. Artificial light pollution: Shifting spectral wavelengths to mitigate physiological and health consequences in a nocturnal marsupial mammal.

    Science.gov (United States)

    Dimovski, Alicia M; Robert, Kylie A

    2018-05-02

    The focus of sustainable lighting tends to be on reduced CO 2 emissions and cost savings, but not on the wider environmental effects. Ironically, the introduction of energy-efficient lighting, such as light emitting diodes (LEDs), may be having a great impact on the health of wildlife. These white LEDs are generated with a high content of short-wavelength 'blue' light. While light of any kind can suppress melatonin and the physiological processes it regulates, these short wavelengths are potent suppressors of melatonin. Here, we manipulated the spectral composition of LED lights and tested their capacity to mitigate the physiological and health consequences associated with their use. We experimentally investigated the impact of white LEDs (peak wavelength 448 nm; mean irradiance 2.87 W/m 2 ), long-wavelength shifted amber LEDs (peak wavelength 605 nm; mean irradiance 2.00 W/m 2 ), and no lighting (irradiance from sky glow light treatments. White LED exposed wallabies had significantly suppressed nocturnal melatonin compared to no light and amber LED exposed wallabies, while there was no difference in lipid peroxidation. Antioxidant capacity declined from baseline to week 10 under all treatments. These results provide further evidence that short-wavelength light at night is a potent suppressor of nocturnal melatonin. Importantly, we also illustrate that shifting the spectral output to longer wavelengths could mitigate these negative physiological impacts. © 2018 Wiley Periodicals, Inc.

  7. The Workplace Literacy System Project (WLS). Final Performance Report.

    Science.gov (United States)

    Poulton, Bruce R.

    The Workplace Literacy System Project (WLS) prepared interactive CD-ROM discs containing about 50 hours of instruction and drill in basic skills presented within the context of the textile/apparel manufacturing industry. The project was conducted at a Sara Lee knit products plant in North Carolina. During the project, literacy task analyses were…

  8. Wavelength shifter strips and G-APD arrays for the read-out of the z-coordinate in axial PET modules

    CERN Document Server

    Braem, André; Joram, C; Rudge, A; Séguinot, Jacques; Weilhammer, P; De Leo, R; Nappi, E; Lustermann, W; Schinzel, D; Johnson, I; Renker, D; Albrecht, S

    2008-01-01

    The measurements presented in this paper are related to the development of a PET camera based on a 3-D axial geometry with excellent 3-D spatial, timing and energy resolution. The detector modules consist of matrices of long axially oriented scintillation crystal bars, which are individually coupled to photodetectors. The axial coordinate is derived from wavelength shifting (WLS) plastic strips orthogonally interleaved between the crystal bars and readout by G-APD arrays. We report on results from measurements with two LYSO crystal bars, read with PMTs, and two WLS strips readout with G-APD devices from Hamamatsu (called MPPC). The WLS strips are positioned orthogonally underneath the LYSO bars. Yields of about 80 photoelectrons from the WLS strips for an energy deposition in the LYSO crystals equivalent to the absorption of 511 keV photons are observed. The axial coordinate in the LYSO bars is reconstructed with a precision of about 1.9 mm (FWHM) using a digital reconstruction method. The resolution of an an...

  9. Plasma shifts of C VI Lyman lines to shorter wavelengths. Final report, November 4, 1981-September 30, 1983

    International Nuclear Information System (INIS)

    Griem, H.R.

    1984-07-01

    The first two years of this ongoing research program were devoted to experimental observations of shifts and widths of hydrogenic ion lines emitted by very dense plasmas. This search is an essential step in the general study of the properties of bound states of multiply charged ions in dense plasmas. This research is of importance in a number of areas, notably equilibrium statistical mechanics (equation of state), plasma radiation physics (energy transport and diagnostics) and calibration of wavelengths in the extreme vacuum uv region (10 A < lambda < 200 A). In the latter case, the wavelengths of lines from one-electron ions are generally accepted to be well known theoretically and are considered as standards for plate calibration. The question nevertheless arises whether or not significant changes in wavelength can occur, e.g., in low-inductance sparks or laser produced plasma which are often used as line sources

  10. Mitigating of modal instabilities in linearly-polarized fiber amplifiers by shifting pump wavelength

    International Nuclear Information System (INIS)

    Tao, Rumao; Ma, Pengfei; Wang, Xiaolin; Zhou, Pu; Liu, Zejin

    2015-01-01

    We investigated the effect of pump wavelength on the modal instabilities (MI) in high-power linearly polarized Yb-doped fiber amplifiers. We built a novel semi-analytical model to determine the frequency coupling characteristics and power threshold of MI, which indicates promising MI suppression through pumping at an appropriate wavelength. By pumping at 915 nm, the threshold can be enhanced by a factor of 2.1 as compared to that pumped at 976 nm. Based on a high-power linearly polarized fiber amplifier platform, we studied the influence of pump wavelength experimentally. A maximal enhancement factor of 1.9 has been achieved when pumped at 915 nm, which agrees with the theoretical calculation and verified our theoretical model. Furthermore, we show that MI suppression by detuning the pump wavelength is weakened for fiber with a large core-to-cladding ratio. (paper)

  11. Synthesis of multi-wavelength temporal phase-shifting algorithms optimized for high signal-to-noise ratio and high detuning robustness using the frequency transfer function

    OpenAIRE

    Servin, Manuel; Padilla, Moises; Garnica, Guillermo

    2016-01-01

    Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for interferometry is well-known and firmly based on the frequency transfer function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors are present. The FTF-based synthesis for dual-wavelength PSA (DW-PSA) is optimized for high signal-to-noise ratio and minimum number of temporal phase-shifted interferograms. The DW-PSA synthesi...

  12. Radiation hardness of WLS fibres for the ATLAS Tile Calorimeter

    CERN Document Server

    David, M; Maio, A

    2007-01-01

    In this document we present the data obtained in the irradiation in a Co-60 source of WLS fibers for the TileCal calorimeter. The optical, mechanical and radiation hardness properties of these fibers were developed in close contact with three producers: Bicron, Kuraray and Pol.Hi.Tech. The results on the degradation of the light output and attenuation length from five irradiations are presented. The fibers were irradiated with a total dose at least 3 times higher than the dose predicted for 10 years of operation of LHC at nominal luminosity.

  13. Enhancement and wavelength-shifted emission of Cerenkov luminescence using multifunctional microspheres

    International Nuclear Information System (INIS)

    Li, Joanne; Dobrucki, Lawrence W; Marjanovic, Marina; Chaney, Eric J; Suslick, Kenneth S; Boppart, Stephen A

    2015-01-01

    Cerenkov luminescence (CL) imaging is a new molecular imaging modality that utilizes the photons emitted during radioactive decay when charged particles travel faster than the phase velocity of light in a dielectric medium. Here we present a novel agent to convert and increase CL emission at longer wavelengths using multimodal protein microspheres (MSs). The 64 Cu-labeled protein microspheres contain quantum dots (QDs) encapsulated within a high-refractive-index-oil core. Dark box imaging of the MSs was conducted to demonstrate the improvement in CL emission at longer wavelengths. To illustrate the versatile design of these MSs and the potential of CL in disease diagnosis, these MSs were utilized for in vitro cell targeting and ex vivo CL-excited QD fluorescence (CL-FL) imaging of atherosclerotic plaques in rats. It was shown that by utilizing both QDs and MSs with a high-refractive-index-oil core, the CL emission increases by four-fold at longer wavelengths. Furthermore, we demonstrate that these MSs generate both an in vivo and ex vivo contrast signal. The design concept of utilizing QDs and high-index core MSs may contribute to future developments of in vivo CL imaging. (paper)

  14. Development of a two-dimensional imaging detector based on a neutron scintillator with wavelength-shifting fibers

    CERN Document Server

    Sakai, K; Oku, T; Morimoto, K; Shimizu, H M; Tokanai, F; Gorin, A; Manuilov, I V; Ryazantsev, A; Ino, T; Kuroda, K; Suzuki, J

    2002-01-01

    For evaluating neutron optical devices, a two-dimensional (2D) detector based on a neutron scintillator with wavelength-shifting fibers has been developed at RIKEN. We have investigated a ZnS(Ag)+LiF and a Li glass plate as neutron scintillators with the coding technique for realizing the large sensitive area of 50 x 50 mm sup 2. After fabricating the 2D detector, its performance was tested using cold neutrons at JAERI. As a result, a spatial resolution of propor to 1.0 mm was obtained. (orig.)

  15. Estimation of time delay and wavelength shift for highly nonlinear multilayer waveguide by using time transformation approach

    Science.gov (United States)

    Chatterjee, Roshmi; Basu, Mousumi

    2018-02-01

    The well known time transformation method is used here to derive the temporal and spectral electric field distribution at the output end of a multilayer waveguide which consists of different layers of Kerr nonlinear media. A highly nonlinear CS 3-68 glass is considered as one of the materials of the waveguide which mainly comprises of different chalcogenide glass layers. The results indicate that there is sufficient time delay as well as frequency shift between the input and output pulses which is associated with the phenomenon of adiabatic wavelength conversion (AWC). Depending on different arrangements of materials, the time delay and frequency shift can be changed. As a result an input pulse in visible green region can be blue-shifted or red-shifted according to the choices of refractive index of the non-dispersive Kerr nonlinear media. The results show that under certain conditions the input pulse is broadened or compressed for different combinations of materials. This process of AWC also includes the variation of temporal and spectral phase, time delay, temporal peak power etc. For different input pulse shapes the change in time delay is also presented. The study may be useful to find applications of AWC in optical resonators or optical signal processing to be applicable to different photonic devices.

  16. Concentration and size dependence of peak wavelength shift on quantum dots in colloidal suspension

    Science.gov (United States)

    Rinehart, Benjamin S.; Cao, Caroline G. L.

    2016-08-01

    Quantum dots (QDs) are semiconductor nanocrystals that have significant advantages over organic fluorophores, including their extremely narrow Gaussian emission bands and broad absorption bands. Thus, QDs have a wide range of potential applications, such as in quantum computing, photovoltaic cells, biological sensing, and electronics. For these applications, aliasing provides a detrimental effect on signal identification efficiency. This can be avoided through characterization of the QD fluorescence signals. Characterization of the emissivity of CdTe QDs as a function of concentration (1 to 10 mg/ml aqueous) was conducted on 12 commercially available CdTe QDs (emission peaks 550 to 730 nm). The samples were excited by a 50-mW 405-nm laser with emission collected via a free-space CCD spectrometer. All QDs showed a redshift effect as concentration increased. On average, the CdTe QDs exhibited a maximum shift of +35.6 nm at 10 mg/ml and a minimum shift of +27.24 nm at 1 mg/ml, indicating a concentration dependence for shift magnitude. The concentration-dependent redshift function can be used to predict emission response as QD concentration is changed in a complex system.

  17. Simulation and optimisation of a position sensitive scintillation detector with wavelength shifting fibers for thermal neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Herzkamp, Matthias; Engels, Ralf; Kemmerling, Guenter [ZEA-2, Forschungszentrum Juelich (Germany); Brueckel, Thomas [JCNS, Forschungszentrum Juelich (Germany); Stahl, Achim [III. Physikalisches Institut B, RWTH Aachen (Germany); Waasen, Stefan van [ZEA-2, Forschungszentrum Juelich (Germany); Faculty of Engineering, University of Duisburg-Essen (Germany)

    2015-07-01

    In neutron scattering experiments it is important to have position sensitive large scale detectors for thermal neutrons. A detector based on a neutron scintillator with wave length shifting fibers is a new kind of such a detector. We present the simulation of the detector based on the microscopic structure of the scintillation material of the mentioned detector. It consists of a converter and a scintillation powder bound in a matrix. The converter in our case is lithium fluoride with enriched lithium 6, to convert thermal neutrons into high energetic alpha and triton particles. The scintillation material is silver doped zinc sulfide. We show that pulse height spectra obtained by these scintillators can be be explained by the simple model of randomly distributed spheres of zinc sulfide and lithium fluoride. With this model, it is possible to optimise the mass ratio of zinc sulfide to lithium fluoride with respect to detection efficiency and/or energy deposition in zinc sulfide.

  18. A Time Difference Method for Measurement of Phase Shift between Distributed Feedback Laser Diode (DFB-LD Output Wavelength and Intensity

    Directory of Open Access Journals (Sweden)

    Yongning Liu

    2015-07-01

    Full Text Available A time difference method to conveniently measure the phase shift between output wavelength and intensity of distributed feedback laser diodes (DFB-LDs was proposed. This approach takes advantage of asymmetric absorption positions at the same wavelength during wavelength increase and decrease tuning processes in the intensity-time curve by current modulation. For its practical implementation, a measurement example of phase shift was demonstrated by measuring a time difference between the first time and the second time attendances of the same gas absorption line in the intensity-time curve during one sine or triangle modulation circle. The phase shifts at modulation frequencies ranging from 50 Hz to 50 kHz were measured with a resolution of 0.001π. As the modulation frequency increased the shift value increased with a slowed growth rate.

  19. Control of the Rendition Wavelength Shifts of Color Lippmann Holograms Recorded in Single-layer panchromatic Silver-halide Emulsion

    Institute of Scientific and Technical Information of China (English)

    ZHU Jianhua; GUO Lurong; LI Zuoyou; LIU Zhenqing

    2000-01-01

    Russian PFG-03C panchromatic ultra-high resolution silver-halide emulsion is regarded as the most successful material for the fabrication of color reflection holograms. But the lack of established and reliable processing sequences prevents its practical applications in business and everyday life. Though much attention is drawn upon the processing of PFG-03C color reflection holograms, the color desaturation is still a problem. The article describes the new processing of color holograms recorded in PFG- 03C plates which is demonstrated experimentally to have the capacity of controlling the rendition wavelength shifts and improving the color desaturation effectively. The rendition spectra of Red-Green-Blue (R. G. B. ) single-line reflection holographic gratings, and the color reflection hologram as well, are given in this paper.

  20. WLS software for the Los Alamos geophysical instrumentation truck

    International Nuclear Information System (INIS)

    Ideker, C.D.; LaDelfe, C.M.

    1985-01-01

    Los Alamos National Laboratory's capabilities for special downhole geophysical well logging has increased steadily over the past few years. Software was developed originally for each individual tool as it became operational. With little or no standardization for tool software modules, software development became redundant, time consuming, and cost ineffective. With long-term use and the rapid evolution of well logging capacity in mind. Los Alamos and EG and G personnel decided to purchase a software system. The system was designed to offer: wide-range use and programming flexibility; standardization subroutines for tool module development; user friendly operation which would reduce training time; operator error checking and alarm activation; maximum growth capacity for new tools as they are added to the inventory; and the ability to incorporate changes made to the computer operating system and hardware. The end result is a sophisticated and flexible software tool and for transferring downhole geophysical measurement data to computer disk files. This paper outlines the need, design, development, and implementation of the WLS software for geophysical data acquisition. A demonstration and working examples are included in the presentation

  1. Synthesis of multi-wavelength temporal phase-shifting algorithms optimized for high signal-to-noise ratio and high detuning robustness using the frequency transfer function.

    Science.gov (United States)

    Servin, Manuel; Padilla, Moises; Garnica, Guillermo

    2016-05-02

    Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for interferometry is well-known and firmly based on the frequency transfer function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors are present. The FTF-based synthesis for dual-wavelength (DW) PSA is optimized for high signal-to-noise ratio and minimum number of temporal phase-shifted interferograms. The DW-PSA synthesis herein presented may be used for interferometric contouring of discontinuous industrial objects. Also DW-PSA may be useful for DW shop-testing of deep free-form aspheres. As shown here, using the FTF-based synthesis one may easily find explicit DW-PSA formulae optimized for high signal-to-noise and high detuning robustness. To this date, no general synthesis and analysis for temporal DW-PSAs has been given; only ad hoc DW-PSAs formulas have been reported. Consequently, no explicit formulae for their spectra, their signal-to-noise, their detuning and harmonic robustness has been given. Here for the first time a fully general procedure for designing DW-PSAs (or triple-wavelengths PSAs) with desire spectrum, signal-to-noise ratio and detuning robustness is given. We finally generalize DW-PSA to higher number of wavelength temporal PSAs.

  2. An investigation of various wavelength-shifting compounds for improving counting efficiency when 32P-cerenkov radiation is measured in aqueous samples

    NARCIS (Netherlands)

    Ginkel, G. van

    Various water-soluble wavelength-shifting compounds were investigated to assess their suitability for the improvement of counting efficiency when erenkov radiation from phosphorous-32 is measured in a liquid scintillation counter. Of these compounds esculin, β-methyl-umbelliferon and sodium

  3. An investigation of various wavelength-shifting compounds for improving counting efficiency when 32P-Cerenkov radiation is measured in aqueous samples

    International Nuclear Information System (INIS)

    Ginkel, G. van

    1980-01-01

    Various water-soluble wavelength-shifting compounds were investigated to assess their suitability for the improvement of counting efficiency when Cerenkov radiation from phosphorous-32 is measured in a liquid scintillation counter. Of these compounds esculin, β-methyl-umbelliferon and sodium salicylate led to the greatest improvement in counting efficiency. Especially esculin and β-methyl-umbelliferon are fairly stable under a variety of experimental conditions and improve counting efficiencies by a factor of about 1.3 and 1.2 respectively. The use of ethanol as a water-miscible solvent combined with wavelength shifters soluble in both solvents does not improve counting efficiency. (author)

  4. Highly coherent red-shifted dispersive wave generation around 1.3 μm for efficient wavelength conversion

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xia; Bi, Wanjun [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Chen, Wei; Xue, Tianfeng; Hu, Lili; Liao, Meisong, E-mail: liaomeisong@siom.ac.cn [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Gao, Weiqing [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009 (China)

    2015-03-14

    This research investigates the mechanism of the optical dispersive wave (DW) and proposes a scheme that can realize an efficient wavelength conversion. In an elaborately designed photonic crystal fiber, a readily available ytterbium laser operating at ∼1 μm can be transferred to the valuable 1.3 μm wavelength range. A low-order soliton is produced to concentrate the energy of the DW into the target wavelength range and improve the degree of coherence. The input chirp is demonstrated to be a factor that enhances the wavelength conversion efficiency. With a positive initial chirp, 76.6% of the pump energy in the fiber can be transferred into a spectral range between 1.24 and 1.4 μm. With the use of a grating compressor, it is possible to compress the generated coherent DW of several picoseconds into less than 90 fs.

  5. Modeling the focusing efficiency of lobster-eye optics for image shifting depending on the soft x-ray wavelength.

    Science.gov (United States)

    Su, Luning; Li, Wei; Wu, Mingxuan; Su, Yun; Guo, Chongling; Ruan, Ningjuan; Yang, Bingxin; Yan, Feng

    2017-08-01

    Lobster-eye optics is widely applied to space x-ray detection missions and x-ray security checks for its wide field of view and low weight. This paper presents a theoretical model to obtain spatial distribution of focusing efficiency based on lobster-eye optics in a soft x-ray wavelength. The calculations reveal the competition mechanism of contributions to the focusing efficiency between the geometrical parameters of lobster-eye optics and the reflectivity of the iridium film. In addition, the focusing efficiency image depending on x-ray wavelengths further explains the influence of different geometrical parameters of lobster-eye optics and different soft x-ray wavelengths on focusing efficiency. These results could be beneficial to optimize parameters of lobster-eye optics in order to realize maximum focusing efficiency.

  6. Tests of Scintillator+WLS Strips for Muon System at Future Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Dmitri [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Evdokimov, Valery [Inst. for High Energy Physics (IHEP), Protvino (Russian Federation); Lukić, Strahinja [Univ. of Belgrade (Serbia)

    2015-10-11

    Prototype scintilator+WLS strips with SiPM readout for muon system at future colliders were tested for light yield, time resolution and position resolution. Depending on the configuration, light yield of up to 36 photoelectrons per muon per SiPM has been achieved, as well as time resolution of 0.5 ns and position resolution of ~ 7 cm.

  7. Calibration of ground-based Lidar instrument WLS7-73

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given WLS7 Windcube at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement uncertain...

  8. Apparent wavelength shifts of H-like ions caused by the spectral fine structure observed in CHS plasmas

    International Nuclear Information System (INIS)

    Nishimura, Shin; Ida, Katsumi

    1998-01-01

    A new charge exchange spectroscopy (CXS) system viewing the plasma from the upside and the downside simultaneously was installed on the Compact Helical System (CHS) to detect the absolute value of Doppler shift due to poloidal rotation velocity ( i ∼ 100 eV) and in the after-glow recombining phase (T i ∼ 30 eV). The apparent Doppler shift is always red-shift regardless the direction of plasma rotation and is explained as the effect of the spectral fine structure of hydrogen-like ions. (author)

  9. Widely tunable dispersive wave generation and soliton self-frequency shift in a tellurite microstructured optical fiber pumped near the zero dispersion wavelength

    International Nuclear Information System (INIS)

    Zhang, Lei; Tuan, Tong-Hoang; Liu, Lai; Gao, Wei-Qing; Kawamura, Harutaka; Suzuki, Takenobu; Ohishi, Yasutake

    2015-01-01

    Widely tunable dispersive waves (DW) and Raman solitons are generated in a tellurite microstructured optical fiber (TMOF) by pumping in the anomalous dispersion regime, close to the zero dispersion wavelength (ZDW). The DW can be generated from 1518.3 nm to 1315.5 nm, and the soliton can be shifted from the pump wavelength of 1570 nm to 1828.7 nm, by tuning the average pump power from 3 dBm to 17.5 dBm. After the average pump power is increased to 18.8 dBm, two DW peaks (centered at 1323 nm and 1260 nm) and three soliton peaks (centered at 1762 nm, 1825 nm, and 1896 nm) can be observed simultaneously. When the average pump power is greater than 23.4 dBm, a flat and broadband supercontinuum (SC) can be formed by the combined nonlinear effects of soliton self-frequency shift (SSFS), DW generation, and cross phase modulation (XPM). (paper)

  10. Noise tolerance in wavelength-selective switching of optical differential quadrature-phase-shift-keying pulse train by collinear acousto-optic devices.

    Science.gov (United States)

    Goto, Nobuo; Miyazaki, Yasumitsu

    2014-06-01

    Optical switching of high-bit-rate quadrature-phase-shift-keying (QPSK) pulse trains using collinear acousto-optic (AO) devices is theoretically discussed. Since the collinear AO devices have wavelength selectivity, the switched optical pulse trains suffer from distortion when the bandwidth of the pulse train is comparable to the pass bandwidth of the AO device. As the AO device, a sidelobe-suppressed device with a tapered surface-acoustic-wave (SAW) waveguide and a Butterworth-type filter device with a lossy SAW directional coupler are considered. Phase distortion of optical pulse trains at 40 to 100  Gsymbols/s in QPSK format is numerically analyzed. Bit-error-rate performance with additive Gaussian noise is also evaluated by the Monte Carlo method.

  11. Measurement of parameters of scintillating bars with wavelength-shifting fibres and silicon photomultiplier readout for the SHiP Muon Detector

    CERN Document Server

    Montanari, Alessandro; Baldini, Wander; Calcaterra, Alessandro; Lanfranchi, Gaia; Saputi, Alessandro; Khotyantsev, Alexey; Kudenko, Yury; Mefodev, Aleksandr; Mineev, Oleg

    2016-01-01

    The light yield and the time resolution of different types of 3 m long scintillating bars instrumented with wavelength shifting fibres and read out by different models of silicon photomultipliers have been measured at a test beam at the T9 area at the CERN Proton Synchrotron. The results obtained with different configurations are presented. A time resolution better than 800 ps, constant along the bar length within 20%, and a light yield of 140 (70) photo-electrons are obtained for bars 3 m long, 4.5 (5) cm wide and 2 (0.7) cm thick. These results nicely match the requirements for the Muon Detector of the SHiP experiment.

  12. Detector for the FSD Fourier-diffractometer based on ZnS(Ag)/6LiF scintillation screen and wavelength shifting fibers readout

    International Nuclear Information System (INIS)

    Kuz'min, E.S.; Balagurov, A.M.; Bokuchava, G.D.; Zhuk, V.V.; Kudryashev, V.A.; Bulkin, A.P.; Trunov, V.A.

    2001-01-01

    At the IBR-2 pulsed reactor (FLNP, JINR, Dubna), a specialized time-of-flight instrument Fourier-Stress-Diffractometer (FSD) intended for the measurement of internal stresses in bulk samples by using high-resolution neutron diffraction is under construction. One of the main components of the diffractometer is a new-type detector with combined electronic - geometrical focusing uniting a large solid angle and a small geometry contribution to the instrumental resolution. The first two modules of the detector, based on scintillation screen ZnS(Ag)/ 6 LiF with wavelength shifting fibers readout have been developed and tested. The design of the detector and associated electronics are described. The method of time focusing surface approximation, using the screen flexibility is proposed. Characteristics of the tested modules in comparison with a detector of the previous generation are presented and advantages of the new detector design for high-resolution diffractometry are discussed

  13. On the calibration process of film dosimetry: OLS inverse regression versus WLS inverse prediction

    International Nuclear Information System (INIS)

    Crop, F; Thierens, H; Rompaye, B Van; Paelinck, L; Vakaet, L; Wagter, C De

    2008-01-01

    The purpose of this study was both putting forward a statistically correct model for film calibration and the optimization of this process. A reliable calibration is needed in order to perform accurate reference dosimetry with radiographic (Gafchromic) film. Sometimes, an ordinary least squares simple linear (in the parameters) regression is applied to the dose-optical-density (OD) curve with the dose as a function of OD (inverse regression) or sometimes OD as a function of dose (inverse prediction). The application of a simple linear regression fit is an invalid method because heteroscedasticity of the data is not taken into account. This could lead to erroneous results originating from the calibration process itself and thus to a lower accuracy. In this work, we compare the ordinary least squares (OLS) inverse regression method with the correct weighted least squares (WLS) inverse prediction method to create calibration curves. We found that the OLS inverse regression method could lead to a prediction bias of up to 7.3 cGy at 300 cGy and total prediction errors of 3% or more for Gafchromic EBT film. Application of the WLS inverse prediction method resulted in a maximum prediction bias of 1.4 cGy and total prediction errors below 2% in a 0-400 cGy range. We developed a Monte-Carlo-based process to optimize calibrations, depending on the needs of the experiment. This type of thorough analysis can lead to a higher accuracy for film dosimetry

  14. Combined Forecasting Method of Landslide Deformation Based on MEEMD, Approximate Entropy, and WLS-SVM

    Directory of Open Access Journals (Sweden)

    Shaofeng Xie

    2017-01-01

    Full Text Available Given the chaotic characteristics of the time series of landslides, a new method based on modified ensemble empirical mode decomposition (MEEMD, approximate entropy and the weighted least square support vector machine (WLS-SVM was proposed. The method mainly started from the chaotic sequence of time-frequency analysis and improved the model performance as follows: first a deformation time series was decomposed into a series of subsequences with significantly different complexity using MEEMD. Then the approximate entropy method was used to generate a new subsequence for the combination of subsequences with similar complexity, which could effectively concentrate the component feature information and reduce the computational scale. Finally the WLS-SVM prediction model was established for each new subsequence. At the same time, phase space reconstruction theory and the grid search method were used to select the input dimension and the optimal parameters of the model, and then the superposition of each predicted value was the final forecasting result. Taking the landslide deformation data of Danba as an example, the experiments were carried out and compared with wavelet neural network, support vector machine, least square support vector machine and various combination schemes. The experimental results show that the algorithm has high prediction accuracy. It can ensure a better prediction effect even in landslide deformation periods of rapid fluctuation, and it can also better control the residual value and effectively reduce the error interval.

  15. Wavelength-shifting fiber signal readout from Transparent RUbber SheeT (TRUST) type LiCaAlF{sub 6} neutron scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Kenichi, E-mail: k-watanabe@nucl.nagoya-u.ac.jp [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Yamazaki, Takuya; Sugimoto, Dai; Yamazaki, Atsushi; Uritani, Akira; Iguchi, Tetsuo [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Fukuda, Kentaro; Ishidu, Sumito [Tokuyama Corporation, Shunan 745-8648 (Japan); Yanagida, Takayuki; Fujimoto, Yutaka [Kyushu Institute of Technology, Kita-kyushu 808-0196 (Japan)

    2015-06-01

    As an alternative to the standard {sup 3}He neutron detector, we are developing the Transparent RUbber SheeT type (TRUST) Eu doped LiCaAlF{sub 6} (Eu:LiCAF) scintillator. This type of neutron scintillator can easily be fabricated as a large area sheet. In order to take advantage of a large area detector, we try to readout scintillation photons using a wavelength-shifting fiber (WLSF) from a TRUST Eu:LiCAF scintillator. The TRUST Eu:LiCAF scintillator with the size of 50×50×5 mm{sup 3} was mounted on the WLSF plate and the end of the WLSFs was connected with a PMT. In order to reject high pulse height events induced in the WLSFs, we applied the pulse shape discrimination technique. The gamma-ray intrinsic and neutron absolute detection efficiency is evaluated to be 8.8×10{sup −7} and 9×10{sup −3} cps/ng Cf (2 m) for the TRUST Eu:LiCAF scintillator with the size of 50×50×5 mm{sup 3}.

  16. Wavelength-shifting fiber signal readout from Transparent RUbber SheeT (TRUST) type LiCaAlF6 neutron scintillator

    International Nuclear Information System (INIS)

    Watanabe, Kenichi; Yamazaki, Takuya; Sugimoto, Dai; Yamazaki, Atsushi; Uritani, Akira; Iguchi, Tetsuo; Fukuda, Kentaro; Ishidu, Sumito; Yanagida, Takayuki; Fujimoto, Yutaka

    2015-01-01

    As an alternative to the standard 3 He neutron detector, we are developing the Transparent RUbber SheeT type (TRUST) Eu doped LiCaAlF 6 (Eu:LiCAF) scintillator. This type of neutron scintillator can easily be fabricated as a large area sheet. In order to take advantage of a large area detector, we try to readout scintillation photons using a wavelength-shifting fiber (WLSF) from a TRUST Eu:LiCAF scintillator. The TRUST Eu:LiCAF scintillator with the size of 50×50×5 mm 3 was mounted on the WLSF plate and the end of the WLSFs was connected with a PMT. In order to reject high pulse height events induced in the WLSFs, we applied the pulse shape discrimination technique. The gamma-ray intrinsic and neutron absolute detection efficiency is evaluated to be 8.8×10 −7 and 9×10 −3 cps/ng Cf (2 m) for the TRUST Eu:LiCAF scintillator with the size of 50×50×5 mm 3

  17. Measurement of wavelengths and lamb shifts for inner-shell transitions in Fe XVIII-XXIV. [from solar flare X-ray spectra

    Science.gov (United States)

    Seely, J. F.; Feldman, U.; Safronova, U. I.

    1986-01-01

    The wavelengths of inner-shell 1s-2p transitions in the ions Fe XVIII-XXIV have been measured in solar flare spectra recorded by the Naval Research Laboratory crystal spectrometer (SOLFLEX) on the Air Force P78-1 spacecraft. The measurements are compared with previous measurements and with recently calculated wavelengths. It is found that the measured wavelengths are systematically larger than the wavelengths calculated using the Z-expansion method by up to 0.65 mA. For the more highly charged ions, these differences can be attributed to the QED contributions to the transition energies that are not included in the Z-expansion calculations.

  18. Shifting wavelengths of ultraweak photon emissions from dying melanoma cells: their chemical enhancement and blocking are predicted by Cosic's theory of resonant recognition model for macromolecules.

    Science.gov (United States)

    Dotta, Blake T; Murugan, Nirosha J; Karbowski, Lukasz M; Lafrenie, Robert M; Persinger, Michael A

    2014-02-01

    During the first 24 h after removal from incubation, melanoma cells in culture displayed reliable increases in emissions of photons of specific wavelengths during discrete portions of this interval. Applications of specific filters revealed marked and protracted increases in infrared (950 nm) photons about 7 h after removal followed 3 h later by marked and protracted increases in near ultraviolet (370 nm) photon emissions. Specific wavelengths within the visible (400 to 800 nm) peaked 12 to 24 h later. Specific activators or inhibitors for specific wavelengths based upon Cosic's resonant recognition model elicited either enhancement or diminishment of photons at the specific wavelength as predicted. Inhibitors or activators predicted for other wavelengths, even within 10 nm, were less or not effective. There is now evidence for quantitative coupling between the wavelength of photon emissions and intrinsic cellular chemistry. The results are consistent with initial activation of signaling molecules associated with infrared followed about 3 h later by growth and protein-structural factors associated with ultraviolet. The greater-than-expected photon counts compared with raw measures through the various filters, which also function as reflective material to other photons, suggest that photons of different wavelengths might be self-stimulatory and could play a significant role in cell-to-cell communication.

  19. A superconducting wavelength shifter as primary radiometric source standard in the X-ray range

    Energy Technology Data Exchange (ETDEWEB)

    Klein, R. [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany)], E-mail: roman.klein@ptb.de; Brandt, G.; Cibik, L.; Gerlach, M.; Krumrey, M.; Mueller, P.; Ulm, G. [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany); Scheer, M. [BESSY GmbH, Albert-Einstein-Strasse 15, 12489 Berlin (Germany)

    2007-10-11

    For more than 20 years, the Physikalisch-Technische Bundesanstalt (PTB) has been using the calculable radiation of bending magnets from the BESSY I and BESSY II electron storage rings in the visible, UV, vacuum-UV (VUV) and X-ray spectral range for radiometry, especially for the calibration of radiation sources and energy-dispersive detectors. Due to its-compared to bending magnets-higher magnetic field, wavelength shifters (WLS) have the potential to extend the usable spectral range for these applications to higher photon energies. Thus, the characteristic energies of BESSY II bending magnet radiation and a 6 T WLS radiation are 2.5 and 11.5 keV, respectively. Within the scope of this work, the properties of the synchrotron radiation from the 6 T WLS have been investigated and compared to theoretical predictions for photon energies up to 150 keV. Good agreement within the experimental uncertainty of several percent was found. Further improvements for a future radiometric use of WLS radiation with low uncertainties will be discussed.

  20. A superconducting wavelength shifter as primary radiometric source standard in the X-ray range

    International Nuclear Information System (INIS)

    Klein, R.; Brandt, G.; Cibik, L.; Gerlach, M.; Krumrey, M.; Mueller, P.; Ulm, G.; Scheer, M.

    2007-01-01

    For more than 20 years, the Physikalisch-Technische Bundesanstalt (PTB) has been using the calculable radiation of bending magnets from the BESSY I and BESSY II electron storage rings in the visible, UV, vacuum-UV (VUV) and X-ray spectral range for radiometry, especially for the calibration of radiation sources and energy-dispersive detectors. Due to its-compared to bending magnets-higher magnetic field, wavelength shifters (WLS) have the potential to extend the usable spectral range for these applications to higher photon energies. Thus, the characteristic energies of BESSY II bending magnet radiation and a 6 T WLS radiation are 2.5 and 11.5 keV, respectively. Within the scope of this work, the properties of the synchrotron radiation from the 6 T WLS have been investigated and compared to theoretical predictions for photon energies up to 150 keV. Good agreement within the experimental uncertainty of several percent was found. Further improvements for a future radiometric use of WLS radiation with low uncertainties will be discussed

  1. A superconducting wavelength shifter as primary radiometric source standard in the X-ray range

    Science.gov (United States)

    Klein, R.; Brandt, G.; Cibik, L.; Gerlach, M.; Krumrey, M.; Müller, P.; Ulm, G.; Scheer, M.

    2007-10-01

    For more than 20 years, the Physikalisch-Technische Bundesanstalt (PTB) has been using the calculable radiation of bending magnets from the BESSY I and BESSY II electron storage rings in the visible, UV, vacuum-UV (VUV) and X-ray spectral range for radiometry, especially for the calibration of radiation sources and energy-dispersive detectors. Due to its—compared to bending magnets—higher magnetic field, wavelength shifters (WLS) have the potential to extend the usable spectral range for these applications to higher photon energies. Thus, the characteristic energies of BESSY II bending magnet radiation and a 6 T WLS radiation are 2.5 and 11.5 keV, respectively. Within the scope of this work, the properties of the synchrotron radiation from the 6 T WLS have been investigated and compared to theoretical predictions for photon energies up to 150 keV. Good agreement within the experimental uncertainty of several percent was found. Further improvements for a future radiometric use of WLS radiation with low uncertainties will be discussed.

  2. Verification test for three WindCube WLS7 LiDARs at the Høvsøre test site

    DEFF Research Database (Denmark)

    Gottschall, Julia; Courtney, Michael

    The report describes the procedure of testing ground-based WindCube lidars (manufactured by the French company Leosphere) at the Høvsøre test site in comparison to reference sensors mounted at a meteorological mast. Results are presented for three tested units – in detail for unit WLS7-0062, and ......-0062, and in a summary for units WLS7-0064 and WLS7-0066. The verification test covers the evaluation of measured mean wind speeds, wind directions and wind speed standard deviations. The data analysis is basically performed in terms of different kinds of regression analyses.......The report describes the procedure of testing ground-based WindCube lidars (manufactured by the French company Leosphere) at the Høvsøre test site in comparison to reference sensors mounted at a meteorological mast. Results are presented for three tested units – in detail for unit WLS7...

  3. A Mixed WLS Power System State Estimation Method Integrating a Wide-Area Measurement System and SCADA Technology

    Directory of Open Access Journals (Sweden)

    Tao Jin

    2018-02-01

    Full Text Available To address the issue that the phasor measurement units (PMUs of wide area measurement system (WAMS are not sufficient for static state estimation in most existing power systems, this paper proposes a mixed power system weighted least squares (WLS state estimation method integrating a wide-area measurement system and supervisory control and data acquisition (SCADA technology. The hybrid calculation model is established by incorporating phasor measurements (including the node voltage phasors and branch current phasors and the results of the traditional state estimator in a post-processing estimator. The performance assessment is discussed through setting up mathematical models of the distribution network. Based on PMU placement optimization and bias analysis, the effectiveness of the proposed method was proved to be accurate and reliable by simulations of different cases. Furthermore, emulating calculation shows this method greatly improves the accuracy and stability of the state estimation solution, compared with the traditional WLS state estimation.

  4. Temperature-Induced Wavelength Shift of Electron-Beam-Pumped Lasers from CdSe, CdS, and ZnO

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1971-01-01

    Experimental results on the temperature dependence of the laser frequency and threshold pump power are presented in the range from liquid helium to room temperature for electron-beam-pumped CdSe, CdS, and ZnO lasers. A linear shift of the laser frequency at high temperatures and a relatively slow...

  5. A Robust WLS Power System State Estimation Method Integrating a Wide-Area Measurement System and SCADA Technology

    Directory of Open Access Journals (Sweden)

    Tao Jin

    2015-04-01

    Full Text Available With the development of modern society, the scale of the power system is rapidly increased accordingly, and the framework and mode of running of power systems are trending towards more complexity. It is nowadays much more important for the dispatchers to know exactly the state parameters of the power network through state estimation. This paper proposes a robust power system WLS state estimation method integrating a wide-area measurement system (WAMS and SCADA technology, incorporating phasor measurements and the results of the traditional state estimator in a post-processing estimator, which greatly reduces the scale of the non-linear estimation problem as well as the number of iterations and the processing time per iteration. This paper firstly analyzes the wide-area state estimation model in detail, then according to the issue that least squares does not account for bad data and outliers, the paper proposes a robust weighted least squares (WLS method that combines a robust estimation principle with least squares by equivalent weight. The performance assessment is discussed through setting up mathematical models of the distribution network. The effectiveness of the proposed method was proved to be accurate and reliable by simulations and experiments.

  6. Spectral shifts of mammalian ultraviolet-sensitive pigments (short wavelength-sensitive opsin 1) are associated with eye length and photic niche evolution.

    Science.gov (United States)

    Emerling, Christopher A; Huynh, Hieu T; Nguyen, Minh A; Meredith, Robert W; Springer, Mark S

    2015-11-22

    Retinal opsin photopigments initiate mammalian vision when stimulated by light. Most mammals possess a short wavelength-sensitive opsin 1 (SWS1) pigment that is primarily sensitive to either ultraviolet or violet light, leading to variation in colour perception across species. Despite knowledge of both ultraviolet- and violet-sensitive SWS1 classes in mammals for 25 years, the adaptive significance of this variation has not been subjected to hypothesis testing, resulting in minimal understanding of the basis for mammalian SWS1 spectral tuning evolution. Here, we gathered data on SWS1 for 403 mammal species, including novel SWS1 sequences for 97 species. Ancestral sequence reconstructions suggest that the most recent common ancestor of Theria possessed an ultraviolet SWS1 pigment, and that violet-sensitive pigments evolved at least 12 times in mammalian history. We also observed that ultraviolet pigments, previously considered to be a rarity, are common in mammals. We then used phylogenetic comparative methods to test the hypotheses that the evolution of violet-sensitive SWS1 is associated with increased light exposure, extended longevity and longer eye length. We discovered that diurnal mammals and species with longer eyes are more likely to have violet-sensitive pigments and less likely to possess UV-sensitive pigments. We hypothesize that (i) as mammals evolved larger body sizes, they evolved longer eyes, which limited transmittance of ultraviolet light to the retina due to an increase in Rayleigh scattering, and (ii) as mammals began to invade diurnal temporal niches, they evolved lenses with low UV transmittance to reduce chromatic aberration and/or photo-oxidative damage. © 2015 The Author(s).

  7. Fine tuning the emission wavelengths of the 7-hydroxy-1-indanone based nano-structure dyes: Near-infrared (NIR) dual emission generation with large stokes shifts

    Science.gov (United States)

    Roohi, Hossein; Alizadeh, Parvaneh

    2018-05-01

    Near-infrared (NIR) fluorescent dyes have recently gained special attention due to their applications to use as molecular probes for imaging of biological targets and sensitive determination. In this study, photophysical properties of the 7-hydroxy-1-indanone based fluorophors A1, A2, A3, B1, B2 and 3R-B2 (R = CF3, NH2, NO2 and OMe) in the gas and three solution phases were probed using TD-DFT method at PBE0/6-311++G(d,p) and M06-2X/6-311++G(d,p) levels of theory. In addition to structural and photophysical properties as well as ESIPT mechanism of all mentioned molecules, the FC and relaxed potential energy surfaces of B2 and 3R-B2 (R = CF3 and NH2) molecules were explored in gas phase and acetonitrile, cyclohexane and water solvents. It is predicted that the A1, A3 and 3R-B2 chromophores afford normal (615-670 nm) and NIR fluorescence emissions (770-940 nm; biological window) with the large Stokes shifts of >160 and >300 nm, respectively. A good aggrement was found between theoretical and experimental results. In sum, these new types of dyes may render the new approaches for the development of the most efficient NIR fluorescent probes for enhanced image contrast and optimal apparent brightness in biological applications.

  8. A model for the Global Quantum Efficiency for a TPB-based wavelength-shifting system used with photomultiplier tubes in liquid argon in MicroBooNE

    Science.gov (United States)

    Pate, S. F.; Wester, T.; Bugel, L.; Conrad, J.; Henderson, E.; Jones, B. J. P.; McLean, A. I. L.; Moon, J. S.; Toups, M.; Wongjirad, T.

    2018-02-01

    We present a model for the Global Quantum Efficiency (GQE) of the MicroBooNE optical units. An optical unit consists of a flat, circular acrylic plate, coated with tetraphenyl butadiene (TPB), positioned near the photocathode of a 20.2-cm diameter photomultiplier tube. The plate converts the ultra-violet scintillation photons from liquid argon into visible-spectrum photons to which the cryogenic phototubes are sensitive. The GQE is the convolution of the efficiency of the plates that convert the 128 nm scintillation light from liquid argon to visible light, the efficiency of the shifted light to reach the photocathode, and the efficiency of the cryogenic photomultiplier tube. We develop a GEANT4-based model of the optical unit, based on first principles, and obtain the range of probable values for the expected number of detected photoelectrons (NPE) given the known systematic errors on the simulation parameters. We compare results from four measurements of the NPE determined using alpha-particle sources placed at two distances from a TPB-coated plate in a liquid argon cryostat test stand. We also directly measured the radial dependence of the quantum efficiency, and find that this has the same shape as predicted by our model. Our model results in a GQE of 0.0055±0.0009 for the MicroBooNE optical units. While the information shown here is MicroBooNE specific, the approach to the model and the collection of simulation parameters will be widely applicable to many liquid-argon-based light collection systems.

  9. Test beam studies of the light yield, time and coordinate resolutions of scintillator strips with WLS fibers and SiPM readout

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Dmitri [Fermilab, Batavia IL (United States); Evdokimov, Valery [Institute for High Energy Physics, Protvino (Russian Federation); Lukić, Strahinja; Ujić, Predrag [Vinča Institute, University of Belgrade (Serbia)

    2017-03-11

    Prototype scintilator+WLS strips with SiPM readout for large muon detection systems were tested in the muon beam of the Fermilab Test Beam Facility. Light yield of up to 137 photoelectrons per muon per strip has been observed , as well as time resolution of 330 ps and position resolution along the strip of 5.4 cm.

  10. Ageing studies of wavelength shifter fibers for the TILECAL/ATLAS experiment

    International Nuclear Information System (INIS)

    Silva, J.; Maio, A.; Pina, J.; Santos, J.; Saraiva, J.G.

    2007-01-01

    Natural and accelerated ageing studies for the different components of the TILECAL calorimeter, of the ATLAS experiment, play a central role in forecasting the evolution of the detector's performance throughout its operating life. It is possible that the operation of ATLAS will be extended by 5 years in an upgraded LHC scenario. Such prospect makes these studies even more important, in order to assess the contribution of the natural ageing in relation to the other processes inducing performance loss in the optical components. Among other activities in this LHC/CERN collaboration, the Lisbon calorimetry group is involved in studying the impact of radiation damage and natural ageing in optical characteristics of the TILECAL wavelength shifter (WLS) optical fibers and scintillators, and to reevaluate the light budget of the tile/fiber system. The light yield and the attenuation length of the WLS and scintillating optical fibers are measured using an X-Y table. Results are presented for several sets of WLS optical fibers (Kuraray Y11(200)MSJ) whose characteristics have been monitored since 1999. Most of those 338 fibers are from the mass production for the TILECAL detector: 208 non-aluminized 200 cm fibers, from several production batches, and 128 batch no. 6 aluminized fibers, with lengths ranging from 114 to 207 cm

  11. View of the inner part of the VO prototype box. The WLS fibers wrapped up in teflon strips are coupled to connectors which ensure the passage of the light outside the box and its transfer in optical fibers.

    CERN Multimedia

    2004-01-01

    View of the inner part of the VO prototype box. The WLS fibers wrapped up in teflon strips are coupled to connectors which ensure the passage of the light outside the box and its transfer in optical fibers.

  12. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers.......Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

  13. A 12 GHz wavelength spacing multi-wavelength laser source for wireless communication systems

    Science.gov (United States)

    Peng, P. C.; Shiu, R. K.; Bitew, M. A.; Chang, T. L.; Lai, C. H.; Junior, J. I.

    2017-08-01

    This paper presents a multi-wavelength laser source with 12 GHz wavelength spacing based on a single distributed feedback laser. A light wave generated from the distributed feedback laser is fed into a frequency shifter loop consisting of 50:50 coupler, dual-parallel Mach-Zehnder modulator, optical amplifier, optical filter, and polarization controller. The frequency of the input wavelength is shifted and then re-injected into the frequency shifter loop. By re-injecting the shifted wavelengths multiple times, we have generated 84 optical carriers with 12 GHz wavelength spacing and stable output power. For each channel, two wavelengths are modulated by a wireless data using the phase modulator and transmitted through a 25 km single mode fiber. In contrast to previously developed schemes, the proposed laser source does not incur DC bias drift problem. Moreover, it is a good candidate for radio-over-fiber systems to support multiple users using a single distributed feedback laser.

  14. Estimation of position resolution for DOI-PET detector using diameter 0.2 mm WLS fibers [ANIMMA--2015-IO-x5

    International Nuclear Information System (INIS)

    Kaneko, Naomi; Ito, H.; Han, S.; Kawai, H.; Kodama, S.; Kobayashi, A.; Tabata, M.; Kamada, K.; Shoji, Y.; Yoshikawa, A.

    2015-01-01

    We have been developing a submillimeter resolution and low-cost DOI-PET detector using wavelength shifting fibers (WLSF), scintillating crystal plates and MPPCs (Hamamatsu Photonics). Conventional design of DOI-PET detectors had approximately mm 3 of resolution by using some scintillating blocks with a volume of 1 mm 3 , which detects gamma-ray. They are expensive due to difficulties in processing scintillating crystals and a large number of photo-detectors, and these technologies are likely to reach the limit of the resolution. Development of a lower cost DOI-PET detector with higher resolution is challenging to popularize the PET diagnosis. We propose two type of PET detector. One is a whole body PET system, and the other is a PET system for brain or small animals. Each PET system consists 6 blocks. The former consists of 6 layers of crystal plates with 300 mm x 300 mm x 4 mm. The latter consists of 16 crystal layers, forming 4 x 4 crystal arrays. The size of the crystal plate is 40 mm x 40 mm x 1 mm. Wavelength shifting fiber (WLSF) sheets are attached to above and up and down side of crystal planes. The whole PET system has 8 MPPCs attached on each side. For the brain PET detector, 9 WLSF fibers are attached on the each side. The expected position resolution would be less than 1 mm at the former system. We have performed an experimental performance estimation for the system component using 22 Na radioactive source. We achieved a collection efficiency of 10% using the WLSF sheet and Ce:Gd 3 (Al,Ga) 5 O 12 (GAGG) crystals at 511 keV. The linear relationship between reconstruction position and incident position was obtained, and a resolution of 0.7 mm (FWHM) for x-axis of DOI by the WLSF readout was achieved. (authors)

  15. Shift Colors

    Science.gov (United States)

    Publications & News Shift Colors Pages default Sign In NPC Logo Banner : Shift Colors Search Navy Personnel Command > Reference Library > Publications & News > Shift Colors Top Link Bar Navy Personnel Library Expand Reference Library Quick Launch Shift Colors Shift Colors Archives Mailing Address How to

  16. Construction of a single/multiple wavelength RZ optical pulse source at 40 GHz by use of wavelength conversion in a high-nonlinearity DSF-NOLM

    DEFF Research Database (Denmark)

    Yu, Jianjun; Yujun, Qian; Jeppesen, Palle

    2001-01-01

    A single or multiple wavelength RZ optical pulse source at 40 GHz is successfully obtained by using wavelength conversion in a nonlinear optical loop mirror consisting of high nonlinearity-dispersion shifted fiber.......A single or multiple wavelength RZ optical pulse source at 40 GHz is successfully obtained by using wavelength conversion in a nonlinear optical loop mirror consisting of high nonlinearity-dispersion shifted fiber....

  17. Wavelength conversion devices

    DEFF Research Database (Denmark)

    Mikkelsen, Benny; Durhuus, Terji; Jørgensen, Carsten

    1996-01-01

    system requirements. The ideal wavelength converter should be transparent to the bit rate and signal format and provide an unchirped output signal with both a high extinction ratio and a large signal-to-noise ratio. It should allow conversion to both shorter and longer wavelengths with equal performance...

  18. Temperature Characteristics of Monolithically Integrated Wavelength-Selectable Light Sources

    International Nuclear Information System (INIS)

    Han Liang-Shun; Zhu Hong-Liang; Zhang Can; Ma Li; Liang Song; Wang Wei

    2013-01-01

    The temperature characteristics of monolithically integrated wavelength-selectable light sources are experimentally investigated. The wavelength-selectable light sources consist of four distributed feedback (DFB) lasers, a multimode interferometer coupler, and a semiconductor optical amplifier. The oscillating wavelength of the DFB laser could be modulated by adjusting the device operating temperature. A wavelength range covering over 8.0nm is obtained with stable single-mode operation by selecting the appropriate laser and chip temperature. The thermal crosstalk caused by the lateral heat spreading between lasers operating simultaneously is evaluated by oscillating-wavelength shift. The thermal crosstalk approximately decreases exponentially as the increasing distance between lasers

  19. Short wavelength FELS

    International Nuclear Information System (INIS)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs

  20. Short wavelength FELS

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs.

  1. Radiation Damage of the CERN CMS HCAL Scintillator/WLS fiber readout during Run1 and Run2 of the LHC

    CERN Document Server

    de Barbaro, Pawel Jan

    2017-01-01

    We present the results of a study of radiation damage of the CERN CMS HCAL Scintillator/WLS Fiber readout. Data were obtained using the Laser calibration system of the CMS hadron endcap detector during the operation of the LHC in 2010-2017. Scintillators used in the CMS hadron endcap calorimeter (HE) were irradiated at dose rates in the range of 0.1 rad/h to 0.1 krad/h. Results indicate that the radiation damage has a strong dose rate dependence. Using data collected in 2017, we have measured the response loss in a single HE section instrumented with Silicon photomultipliers (SiPMs). The results show a much smaller signal loss for the channels read out by SiPMs compared to signal loss for the channels read out by hybrid photodetectors (HPDs). The results imply that a large fraction of the response loss in the CMS HE detector observed in 2010-2017 comes from deterioration of the HPD photodetectors and not from radiation damage of scintillators.

  2. Two-wavelength HeNe laser interferometer

    International Nuclear Information System (INIS)

    Granneman, E.H.A.

    1981-01-01

    This paper presents an interferometer set-up in which two wavelengths are used simultaneously. This enables one to determine separately the phase shifts caused by changes in plasma density and by mechanical vibrations of the interferometer structure

  3. Wavelength dependence of superhumps in VW Hyi

    International Nuclear Information System (INIS)

    Amerongen, S. van; Bovenschen, H.; Paradijs, J. van

    1987-01-01

    Results are presented of five-colour photometric observations of the SU UMa system VW Hyi, made on six nights during the November 1984 superoutburst. The light curve is dominated by superhump variations, whose amplitude in all passbands decreases with time (in the V-band from 0.16 mag about 4.5 day after the superoutburst reached maximum brightness, to 0.10 mag about 5 day later). The superhump light curve depends strongly on wavelength. In particular it appears that the light curves in different passbands are mutually shifted: the larger the wavelength, the more the light curve is delayed. (author)

  4. Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

    DEFF Research Database (Denmark)

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron

    2014-01-01

    numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model...... is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken...

  5. Wavelength conversion technology

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    1998-01-01

    Optical wavelength conversion is currently attracting much interest. This is because it enables full flexibility and eases management of WDM fibre networks. The tutorial will review existing and potential application areas. Examples of node architectures and network demonstrators that use wavelen...

  6. A 16-ch module for thermal neutron detection using ZnS:{sup 6}LiF scintillator with embedded WLS fibers coupled to SiPMs and its dedicated readout electronics

    Energy Technology Data Exchange (ETDEWEB)

    Mosset, J.-B., E-mail: jean-baptiste.mosset@psi.ch; Stoykov, A.; Greuter, U.; Gromov, A.; Hildebrandt, M.; Panzner, T.; Schlumpf, N.

    2017-02-11

    A scalable 16-ch thermal neutron detection system has been developed in the framework of the upgrade of a neutron diffractometer. The detector is based on a ZnS:{sup 6}LiF scintillator with embedded WLS fibers which are read out with SiPMs. In this paper, we present the 16-ch module, the dedicated readout electronics, a direct comparison between the performance of the diffractometer obtained with the current {sup 3}He detector and with the 16-ch detection module, and the channel-to-channel uniformity.

  7. A 16-ch module for thermal neutron detection using ZnS:6LiF scintillator with embedded WLS fibers coupled to SiPMs and its dedicated readout electronics

    Science.gov (United States)

    Mosset, J.-B.; Stoykov, A.; Greuter, U.; Gromov, A.; Hildebrandt, M.; Panzner, T.; Schlumpf, N.

    2017-02-01

    A scalable 16-ch thermal neutron detection system has been developed in the framework of the upgrade of a neutron diffractometer. The detector is based on a ZnS:6LiF scintillator with embedded WLS fibers which are read out with SiPMs. In this paper, we present the 16-ch module, the dedicated readout electronics, a direct comparison between the performance of the diffractometer obtained with the current 3He detector and with the 16-ch detection module, and the channel-to-channel uniformity.

  8. Wavelength sweepable laser source

    DEFF Research Database (Denmark)

    2014-01-01

    Wavelength sweepable laser source is disclosed, wherein the laser source is a semiconductor laser source adapted for generating laser light at a lasing wavelength. The laser source comprises a substrate, a first reflector, and a second reflector. The first and second reflector together defines...... and having a rest position, the second reflector and suspension together defining a microelectromechanical MEMS oscillator. The MEMS oscillator has a resonance frequency and is adapted for oscillating the second reflector on either side of the rest position.; The laser source further comprises electrical...... connections adapted for applying an electric field to the MEMS oscillator. Furthermore, a laser source system and a method of use of the laser source are disclosed....

  9. Shifting Attention

    Science.gov (United States)

    Ingram, Jenni

    2014-01-01

    This article examines the shifts in attention and focus as one teacher introduces and explains an image that represents the processes involved in a numeric problem that his students have been working on. This paper takes a micro-analytic approach to examine how the focus of attention shifts through what the teacher and students do and say in the…

  10. MIT wavelength tables. Volume 2. Wavelengths by element

    International Nuclear Information System (INIS)

    Phelps, F.M. III.

    1982-01-01

    This volume is the first stage of a project to expand and update the MIT wavelength tables first compiled in the 1930's. For 109,325 atomic emission lines, arranged by element, it presents wavelength in air, wavelength in vacuum, wave number and intensity. All data are stored on computer-readable magnetic tape

  11. Evaluation of two thermal neutron detection units consisting of ZnS/{sup 6}LiF scintillating layers with embedded WLS fibers read out with a SiPM

    Energy Technology Data Exchange (ETDEWEB)

    Mosset, J.-B., E-mail: jean-baptiste.mosset@a3.epfl.ch [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N. [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Van Swygenhoven, H. [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland)

    2014-11-11

    Two single channel detection units for thermal neutron detection are investigated in a neutron beam. They consist of two ZnS/{sup 6}LiF scintillating layers sandwiching an array of WLS fibers. The pattern of these units can be repeated laterally and vertically in order to build up a one-dimensional position sensitive multi-channel detector with the needed sensitive surface and with the required neutron absorption probability. The originality of this work arises from the fact that the WLS fibers are read out with SiPMs instead of the traditionally used PMTs or MaPMTs. The signal processing system is based on a photon counting approach. For SiPMs with a dark count rate as high as 0.7 MHz, a trigger efficiency of 80% is achieved together with a system background rate lower than 10{sup −3}Hz and a dead time of 30μs. No change of performance is observed for neutron count rates of up to 3.6 kHz.

  12. Lambda shifted photonic crystal cavity laser

    DEFF Research Database (Denmark)

    Schubert, Martin; Skovgård, Troels Suhr; Ek, Sara

    2010-01-01

    We propose and demonstrate an alternative type of photonic crystal laser design that shifts all the holes in the lattice by a fixed fraction of the targeted emission wavelength. The structures are realized in InGaAsP =1.15 with InGaAsP quantum wells =1.52 as gain material. Cavities with shifts of...

  13. Wavelength tuning of porous silicon microcavities

    International Nuclear Information System (INIS)

    Mulders, J.; Reece, P.; Zheng, W.H.; Lerondel, G.; Sun, B.; Gal, M.

    2002-01-01

    Full text: In the last decade much attention has been given to porous silicon (PS) for optoelectronic applications, which include efficient room temperature light emission as well as microcavity formation. Due to the large specific surface area, the use of porous silicon microcavities (PSMs) has been proposed for chemical sensing. Large wavelength shifts have indicated that the optical properties of PSMs are indeed strongly dependent on the environment. In this paper, we report the shifting of the resonance frequency of high quality PSMs, with the aim of tuning a future PS device to a certain required wavelength. The PSM samples were prepared by anodically etching p + -doped (5mΩcm) bulk silicon wafer in a solution (25%) of aqueous HF and ethanol. The device structure consisted of a PS layer sandwiched between 2 stacks of thin PS layers with alternating high and low effective refractive indices (RI), i.e. distributed Bragg mirrors (DBM). The layer thickness depends on the etch time while the porosity and hence refractive index is determined by the current density as the Si is etched. The position and the width of the stop-band can be fully controlled by the design of the DBMs, with the microcavity resonance mode sitting within the stop-band. We achieved tuning of the microcavity resonance by a number of methods, including temperature dependent tuning. The temperature induced wavelength shift was found to be of the order of 10 -15 nm. Computer modeling of these changes in the reflectivity spectra allowed us to quantify the changes of the effective refractive index and the respective layer thicknesses

  14. Market shifting

    Energy Technology Data Exchange (ETDEWEB)

    Forst, Michael

    2013-11-01

    After years of oversupply and artificially low module pricing, market analysts believe that the solar industry will begin to stabilize by 2017. While the market activities are shifting from Europe to the Asia Pacific region and the United States, the solar shakeout continues to be in full swing including solar cell and module manufacturing. (orig.)

  15. Tough Shift

    DEFF Research Database (Denmark)

    Brewer, Robert S.; Verdezoto, Nervo; Holst, Thomas

    2015-01-01

    people to change their behavior at home. Leveraging prior research on encouraging reductions in residential energy use through game play, we introduce ShareBuddy: a casual mobile game intended to encourage players not only to reduce, but also to shift their electricity use. We conducted two field studies...... real-world resource use into a game....

  16. View of the VO prototype made of two sectors of scintillating counters. WLS fibers embedded within connectors appear in green color. Beams of optical fibers inside black sheath collect and transport the emitted light to photo-multipliers a few meters apart.

    CERN Multimedia

    2004-01-01

    View of the VO prototype made of two sectors of scintillating counters. WLS fibers embedded within connectors appear in green color. Beams of optical fibers inside black sheath collect and transport the emitted light to photo-multipliers a few meters apart.

  17. Multicolor Holography With Phase Shifting

    Science.gov (United States)

    Vikram, Chandra S.

    1996-01-01

    Prototype apparatus constructed to test feasibility of two-color holographic interferometric scheme in which data for reconstructing holographic wavefront obtained with help of phase-shifting technique. Provides two sets of data needed to solve equations for effects of temperature and concentration. Concept extended to holography at three or more wavelengths to measure three or more phenomena associated with significant variations in index of refraction

  18. Digital signal processing for a thermal neutron detector using ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs

    Energy Technology Data Exchange (ETDEWEB)

    Mosset, J.-B., E-mail: jean-baptiste.mosset@psi.ch; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

    2016-07-11

    We present a digital signal processing system based on a photon counting approach which we developed for a thermal neutron detector consisting of ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs. Three digital filters have been evaluated: a moving sum, a moving sum after differentiation and a digital CR-RC{sup 4} filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC{sup 4} filter has been emulated digitally. The detector performance obtained with this analog approach is compared with the one obtained with the best performing digital approach. - Highlights: • Application of digital signal processing for a SiPM-based ZnS:6LiF neutron detector. • Optimisation of detector performances with 3 different digital filters. • Comparison with detector performances with a full analog signal processing.

  19. Fluid Shifts

    Science.gov (United States)

    Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; hide

    2017-01-01

    Introduction. NASA's Human Research Program is focused on addressing health risks associated with long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but now more than 50 percent of ISS astronauts have experienced more profound, chronic changes with objective structural findings such as optic disc edema, globe flattening and choroidal folds. These structural and functional changes are referred to as the visual impairment and intracranial pressure (VIIP) syndrome. Development of VIIP symptoms may be related to elevated intracranial pressure (ICP) secondary to spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to determine if a relation exists with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as any VIIP-related effects of those shifts, are predicted by the crewmember's pre-flight status and responses to acute hemodynamic manipulations, specifically posture changes and lower body negative pressure. Methods. We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, and calcaneus tissue thickness (by ultrasound); (3) vascular dimensions by ultrasound (jugular veins, cerebral and carotid arteries, vertebral arteries and veins, portal vein); (4) vascular dynamics by MRI (head/neck blood flow, cerebrospinal fluid

  20. Topology optimised wavelength dependent splitters

    DEFF Research Database (Denmark)

    Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn

    A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results....... This complex photonic crystal structure is very sensitive against small fabrication variations from the expected topology optimised design. A wavelength dependent splitter is an important basic building block for high-performance nanophotonic circuits. 1J. S. Jensen and O. Sigmund, App. Phys. Lett. 84, 2022...

  1. AWG Filter for Wavelength Interrogator

    Science.gov (United States)

    Black, Richard J. (Inventor); Costa, Joannes M. (Inventor); Faridian, Fereydoun (Inventor); Moslehi, Behzad (Inventor); Sotoudeh, Vahid (Inventor)

    2015-01-01

    A wavelength interrogator is coupled to a circulator which couples optical energy from a broadband source to an optical fiber having a plurality of sensors, each sensor reflecting optical energy at a unique wavelength and directing the reflected optical energy to an AWG. The AWG has a detector coupled to each output, and the reflected optical energy from each grating is coupled to the skirt edge response of the AWG such that the adjacent channel responses form a complementary pair response. The complementary pair response is used to convert an AWG skirt response to a wavelength.

  2. Analysis of reflection-peak wavelengths of sampled fiber Bragg gratings with large chirp.

    Science.gov (United States)

    Zou, Xihua; Pan, Wei; Luo, Bin

    2008-09-10

    The reflection-peak wavelengths (RPWs) in the spectra of sampled fiber Bragg gratings with large chirp (SFBGs-LC) are theoretically investigated. Such RPWs are divided into two parts, the RPWs of equivalent uniform SFBGs (U-SFBGs) and the wavelength shift caused by the large chirp in the grating period (CGP). We propose a quasi-equivalent transform to deal with the CGP. That is, the CGP is transferred into quasi-equivalent phase shifts to directly derive the Fourier transform of the refractive index modulation. Then, in the case of both the direct and the inverse Talbot effect, the wavelength shift is obtained from the Fourier transform. Finally, the RPWs of SFBGs-LC can be achieved by combining the wavelength shift and the RPWs of equivalent U-SFBGs. Several simulations are shown to numerically confirm these predicted RPWs of SFBGs-LC.

  3. Shifting Sugars and Shifting Paradigms

    Science.gov (United States)

    Siegal, Mark L.

    2015-01-01

    No organism lives in a constant environment. Based on classical studies in molecular biology, many have viewed microbes as following strict rules for shifting their metabolic activities when prevailing conditions change. For example, students learn that the bacterium Escherichia coli makes proteins for digesting lactose only when lactose is available and glucose, a better sugar, is not. However, recent studies, including three PLOS Biology papers examining sugar utilization in the budding yeast Saccharomyces cerevisiae, show that considerable heterogeneity in response to complex environments exists within and between populations. These results join similar recent results in other organisms that suggest that microbial populations anticipate predictable environmental changes and hedge their bets against unpredictable ones. The classical view therefore represents but one special case in a range of evolutionary adaptations to environmental changes that all organisms face. PMID:25688600

  4. Shifting sugars and shifting paradigms.

    Directory of Open Access Journals (Sweden)

    Mark L Siegal

    2015-02-01

    Full Text Available No organism lives in a constant environment. Based on classical studies in molecular biology, many have viewed microbes as following strict rules for shifting their metabolic activities when prevailing conditions change. For example, students learn that the bacterium Escherichia coli makes proteins for digesting lactose only when lactose is available and glucose, a better sugar, is not. However, recent studies, including three PLOS Biology papers examining sugar utilization in the budding yeast Saccharomyces cerevisiae, show that considerable heterogeneity in response to complex environments exists within and between populations. These results join similar recent results in other organisms that suggest that microbial populations anticipate predictable environmental changes and hedge their bets against unpredictable ones. The classical view therefore represents but one special case in a range of evolutionary adaptations to environmental changes that all organisms face.

  5. Towards short wavelengths FELs workshop

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Winick, H.

    1993-01-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program

  6. Towards short wavelengths FELs workshop

    Science.gov (United States)

    Ben-Zvi, I.; Winick, H.

    1993-11-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FEL's offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FEL's will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

  7. Wavelength conversion of QAM signals in a low loss CMOS compatible spiral waveguide

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Porto da Silva, Edson; Zibar, Darko

    2017-01-01

    We demonstrate wavelength conversion of quadrature amplitude modulation (QAM) signals, including 32-GBd quadrature phase-shift keying and 10-GBd 16-QAM, in a 50-cm long high index doped glass spiral waveguide. The quality of the generated idlers for up to 20 nm of wavelength shift is sufficient...... to achieve a BER performance below the hard decision forward error correction threshold BER performance (...

  8. Heterodyne detection of CPFSK signals with and without wavelength conversion up to 5 Gb/s

    DEFF Research Database (Denmark)

    Pedersen, Rune Johan Skullerud; Ebskamp, F.; Mikkelsen, Benny

    1993-01-01

    Detection of wavelength converted signals by a coherent continuous-phase frequency-shift-keying receiver is reported. The signals are wavelength converted over 35 nm, and record receiver sensitivities of -38.7 dBm at 4.0Gb/s and -35.6 dBm at 4.8Gb/s are obtained. Comparison between results...

  9. Controlling the emission wavelength in group III-V semiconductor laser diodes

    KAUST Repository

    Ooi, Boon S.; Majid, Mohammed Abdul; Afandy, Rami; Aljabr, Ahmad

    2016-01-01

    Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III

  10. Wavelength dependence of interstellar polarization

    International Nuclear Information System (INIS)

    Mavko, G.E.

    1974-01-01

    The wavelength dependence of interstellar polarization was measured for twelve stars in three regions of the Milky Way. A 120A bandpass was used to measure the polarization at a maximum of sixteen wavelengths evenly spaced between 2.78μ -1 (3600A) and 1.28μ -1 (7800A). For such a wide wavelength range, the wavelength resolution is superior to that of any previously reported polarization measurements. The new scanning polarimeter built by W. A. Hiltner of the University of Michigan was used for the observations. Very broad structure was found in the wavelength dependence of the polarization. Extensive investigations were carried out to show that the structure was not caused by instrumental effects. The broad structure observed is shown to be in agreement with concurrent extinction measurements for the same stars. Also, the observed structure is of the type predicted when a homogeneous silicate grain model is fitted to the observed extinction. The results are in agreement with the hypothesis that the very broad band structure seen in the extinction is produced by the grains. (Diss. Abstr. Int., B)

  11. Three-dimensional cross point readout detector design for including depth information

    Science.gov (United States)

    Lee, Seung-Jae; Baek, Cheol-Ha

    2018-04-01

    We designed a depth-encoding positron emission tomography (PET) detector using a cross point readout method with wavelength-shifting (WLS) fibers. To evaluate the characteristics of the novel detector module and the PET system, we used the DETECT2000 to perform optical photon transport in the crystal array. The GATE was also used. The detector module is made up of four layers of scintillator arrays, the five layers of WLS fiber arrays, and two sensor arrays. The WLS fiber arrays in each layer cross each other to transport light to each sensor array. The two sensor arrays are coupled to the forward and left sides of the WLS fiber array, respectively. The identification of three-dimensional pixels was determined using a digital positioning algorithm. All pixels were well decoded, with the system resolution ranging from 2.11 mm to 2.29 mm at full width at half maximum (FWHM).

  12. Wavelength conversion techniques and devices

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Mikkelsen, Benny; Hansen, Peter Bukhave

    1997-01-01

    Taking into account the requirements to the converters e.g., bit rate transparency (at least up to 10 Gbit/s), polarisation independence, wavelength independence, moderate input power levels, high signal-to-noise ratio and high extinction ratio interferometric wavelength convertors are very...... interesting for use in WDM optical fibre networks. However, the perfect converter has probably not yet been fabricated and new techniques such as conversion relying on cross-absorption modulation in electro-absorption modulators might also be considered in pursue of effective conversion devices...

  13. Sub-wavelength plasmon laser

    Science.gov (United States)

    Bora, Mihail; Bond, Tiziana C.

    2016-04-19

    A plasmonic laser device has resonant nanocavities filled with a gain medium containing an organic dye. The resonant plasmon frequencies of the nanocavities are tuned to align with both the absorption and emission spectra of the dye. Variables in the system include the nature of the dye and the wavelength of its absorption and emission, the wavelength of the pumping radiation, and the resonance frequencies of the nanocavities. In addition the pumping frequency of the dye is selected to be close to the absorption maximum.

  14. Wavelength standards in the infrared

    CERN Document Server

    Rao, KN

    2012-01-01

    Wavelength Standards in the Infrared is a compilation of wavelength standards suitable for use with high-resolution infrared spectrographs, including both emission and absorption standards. The book presents atomic line emission standards of argon, krypton, neon, and xenon. These atomic line emission standards are from the deliberations of Commission 14 of the International Astronomical Union, which is the recognized authority for such standards. The text also explains the techniques employed in determining spectral positions in the infrared. One of the techniques used includes the grating con

  15. Wavelength stabilized multi-kW diode laser systems

    Science.gov (United States)

    Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

    2015-03-01

    We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

  16. Interrogation of weak Bragg grating sensors based on dual-wavelength differential detection.

    Science.gov (United States)

    Cheng, Rui; Xia, Li

    2016-11-15

    It is shown that for weak Bragg gratings the logarithmic ratio of reflected intensities at any two wavelengths within the spectrum follows a linear relationship with the Bragg wavelength shift, with a slope proportional to their wavelength spacing. This finding is exploited to develop a flexible, efficient, and cheap interrogation solution of weak fiber Bragg grating (FBGs), especially ultra-short FBGs, in distributed sensing based on dual-wavelength differential detection. The concept is experimentally studied in both single and distributed sensing systems with ultra-short FBG sensors. The work may form the basis of new and promising FBG interrogation techniques based on detecting discrete rather than continuous spectra.

  17. A dual-wavelength tunable laser with superimposed fiber Bragg gratings

    International Nuclear Information System (INIS)

    Álvarez-Tamayo, R I; Durán-Sánchez, M; Pottiez, O; Ibarra-Escamilla, B; Kuzin, E A; Cruz, J L; Andrés, M V

    2013-01-01

    We report a dual-wavelength tunable fiber laser. The cavity is formed by two superimposed fiber Bragg gratings (FBGs) and a temperature tunable high-birefringence fiber optical loop mirror (FOLM). FBGs with wavelengths of 1548.5 and 1538.5 nm were printed in the same section of a fiber using two different masks. The superimposed FBGs were placed on a mechanical mount that allows stretch or compression of the FBGs. As a result of the FBG strain both lines are shifted simultaneously. Dual-wavelength generation requires a fine adjustment of the cavity loss for both wavelengths. (paper)

  18. Wavelength calibration of imaging spectrometer using atmospheric absorption features

    Science.gov (United States)

    Zhou, Jiankang; Chen, Yuheng; Chen, Xinhua; Ji, Yiqun; Shen, Weimin

    2012-11-01

    Imaging spectrometer is a promising remote sensing instrument widely used in many filed, such as hazard forecasting, environmental monitoring and so on. The reliability of the spectral data is the determination to the scientific communities. The wavelength position at the focal plane of the imaging spectrometer will change as the pressure and temperature vary, or the mechanical vibration. It is difficult for the onboard calibration instrument itself to keep the spectrum reference accuracy and it also occupies weight and the volume of the remote sensing platform. Because the spectral images suffer from the atmospheric effects, the carbon oxide, water vapor, oxygen and solar Fraunhofer line, the onboard wavelength calibration can be processed by the spectral images themselves. In this paper, wavelength calibration is based on the modeled and measured atmospheric absorption spectra. The modeled spectra constructed by the atmospheric radiative transfer code. The spectral angle is used to determine the best spectral similarity between the modeled spectra and measured spectra and estimates the wavelength position. The smile shape can be obtained when the matching process across all columns of the data. The present method is successful applied on the Hyperion data. The value of the wavelength shift is obtained by shape matching of oxygen absorption feature and the characteristics are comparable to that of the prelaunch measurements.

  19. Review of short wavelength lasers

    International Nuclear Information System (INIS)

    Hagelstein, P.L.

    1985-01-01

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references

  20. Review of short wavelength lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hagelstein, P.L.

    1985-03-18

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references.

  1. Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

    Science.gov (United States)

    Potts, C; Allen, T W; Azar, A; Melnyk, A; Dennison, C R; DeCorby, R G

    2014-10-15

    We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10  pm were resolved by employing a simple peak detection algorithm. Si/SiO₂-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1  mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated.

  2. Making Displaced Holograms At Two Wavelengths

    Science.gov (United States)

    Witherow, William K.; Ecker, Andreas

    1989-01-01

    Two-wavelength holographic system augmented with pair of prisms to introduce small separation between holograms formed simultaneously at two wavelengths on holographic plate. Principal use in study of flows. Gradients in index of refraction of fluid caused by variations in temperature, concentration, or both. Holography at one wavelength cannot be used to distinguish between two types of variations. Difference between spacings of fringes in photographs reconstructed from holograms taken simultaneously at two different wavelengths manipulated mathematically to determine type of variation.

  3. Absolute analytical prediction of photonic crystal guided mode resonance wavelengths

    International Nuclear Information System (INIS)

    Hermannsson, Pétur Gordon; Vannahme, Christoph; Smith, Cameron L. C.; Kristensen, Anders

    2014-01-01

    A class of photonic crystal resonant reflectors known as guided mode resonant filters are optical structures that are widely used in the field of refractive index sensing, particularly in biosensing. For the purposes of understanding and design, their behavior has traditionally been modeled numerically with methods such as rigorous coupled wave analysis. Here it is demonstrated how the absolute resonance wavelengths of such structures can be predicted by analytically modeling them as slab waveguides in which the propagation constant is determined by a phase matching condition. The model is experimentally verified to be capable of predicting the absolute resonance wavelengths to an accuracy of within 0.75 nm, as well as resonance wavelength shifts due to changes in cladding index within an accuracy of 0.45 nm across the visible wavelength regime in the case where material dispersion is taken into account. Furthermore, it is demonstrated that the model is valid beyond the limit of low grating modulation, for periodically discontinuous waveguide layers, high refractive index contrasts, and highly dispersive media.

  4. Comparison of different wavelength pump sources for Tm subnanosecond amplifier

    Science.gov (United States)

    Cserteg, Andras; Guillemet, Sébastien; Hernandez, Yves; Giannone, Domenico

    2012-06-01

    We report here a comparison of different pumping wavelengths for short pulse Thulium fibre amplifiers. We compare the results in terms of efficiency and required fibre length. As we operate the laser in the sub-nanosecond regime, the fibre length is a critical parameter regarding non linear effects. With 793 nm clad-pumping, a 4 m long active fibre was necessary, leading to strong spectral deformation through Self Phase Modulation (SPM). Core-pumping scheme was then more in-depth investigated with several wavelengths tested. Good results with Erbium and Raman shifted pumping sources were obtained, with very short fibre length, aiming to reach a few micro-joules per pulse without (or with limited) SPM.

  5. Wavelength modulation spectroscopy of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kohn, S.E.

    1977-10-01

    The use of modulation spectroscopy to study the electronic properties of solids has been very productive. The construction of a wide range Wavelength Modulation Spectrometer to study the optical properties of solids is described in detail. Extensions of the working range of the spectrometer into the vacuum ultraviolet are discussed. Measurements of the reflectivity and derivative reflectivity spectra of the lead chalcogenides, the chalcopyrite ZnGeP/sub 2/, the layer compounds GaSe and GaS and their alloys, the ferroelectric SbSI, layer compounds SnS/sub 2/ and SnSe/sub 2/, and HfS/sub 2/ were made. The results of these measurements are presented along with their interpretation in terms of band structure calculations.

  6. Novel thermal annealing methodology for permanent tuning polymer optical fiber Bragg gratings to longer wavelengths.

    Science.gov (United States)

    Pospori, A; Marques, C A F; Sagias, G; Lamela-Rivera, H; Webb, D J

    2018-01-22

    The Bragg wavelength of a polymer optical fiber Bragg grating can be permanently shifted by utilizing the thermal annealing method. In all the reported fiber annealing cases, the authors were able to tune the Bragg wavelength only to shorter wavelengths, since the polymer fiber shrinks in length during the annealing process. This article demonstrates a novel thermal annealing methodology for permanently tuning polymer optical fiber Bragg gratings to any desirable spectral position, including longer wavelengths. Stretching the polymer optical fiber during the annealing process, the period of Bragg grating, which is directly related with the Bragg wavelength, can become permanently longer. The methodology presented in this article can be used to multiplex polymer optical fiber Bragg gratings at any desirable spectral position utilizing only one phase-mask for their photo-inscription, reducing thus their fabrication cost in an industrial setting.

  7. Design of multi-wavelength tunable filter based on Lithium Niobate

    Science.gov (United States)

    Zhang, Ailing; Yao, Yuan; Zhang, Yue; Song, Hongyun

    2018-05-01

    A multi-wavelength tunable filter is designed. It consists of multiple waveguides among multiple waveguide gratings. A pair of electrodes were placed on both sides of each waveguide. The tunable filter uses the electro-optic effect of Lithium Niobate to tune the phase caused by each waveguide. Consequently, the wavelength and wavelength spacing of the filter are tuned by changing external voltages added on the electrode pairs. The tunable property of the filter is analyzed by phase matching condition and transfer-matrix method. Numerical results show that not only multiple wavelengths with narrow bandwidth are tuned with nearly equal spacing by synchronously changing the voltages added on all electrode pairs, but also the number of wavelengths is determined by the number of phase shifts caused by electrode pairs. Furthermore, due to the electro-optic effect of Lithium Niobate, the tuning speed of the filter can reach the order of ns.

  8. Stable Dual-Wavelength Fibre Laser with Bragg Gratings Fabricated in a Polarization-Maintaining Erbium-Doped Fibre

    International Nuclear Information System (INIS)

    Lin, Wang; Feng-Ping, Yan; Xiang-Qiao, Mao; Shui-Sheng, Jian

    2008-01-01

    A new polarization-independent dual-wavelength fibre laser by fabricating a uniform FBG and a chirped FBG in a polarization-maintaining erbium-doped fibre (PM-EDF) is proposed and demonstrated. The wavelength spacing is 0.18nm and the optical signal-to-noise ratio is greater than 50dB with pump power of 246mW. Chirped FBG is used to make the reflectivity wavelengths of two PM-FBGs match easier. Since both EDF and FBGs are polarization-maintaining without splices and the two wavelengths are polarization-independent, the maximum amplitude variation and wavelength shifts for both lasing wavelength with 3-min intervals over a period of six hours are less than 0.2 dB and 0.005 nm, respectively, which shows stable dual-wavelength output

  9. In-plane wavelength division de-multiplexing using photonic crystals

    DEFF Research Database (Denmark)

    Frandsen, Lars Hagedorn; Harpøth, Anders; Hede, K. K.

    We demonstrate a novel concept for in-plane coarse wavelength division de-multiplexing in integrated photonic circuits utilizing planar photonic crystal waveguides (PhCWs) fabricated in a silicon-on-insulator material. The filtering of wavelength channels is realized by shifting the cut......-off frequency of the fundamental photonic bandgap mode. The shift is obtained by modifying the size of the border holes in consecutive sections of the PhCW1. Simulations and experimental proof-of-principle of the four-channel de-multiplexer will be presented. 1A. Adibi et al., Electron. Lett. 36, 1376...

  10. Micropatch Antenna Phase Shifting

    National Research Council Canada - National Science Library

    Thursby, Michael

    2000-01-01

    .... We have been looking at the ability of embedded element to adjust the phase shift seen by the element with the goal of being able to remove the phase shifting devices from the antenna and replace...

  11. Micropatch Antenna Phase Shifting

    National Research Council Canada - National Science Library

    Thursby, Michael

    1999-01-01

    .... We have been looking at the ability of embedded element to adjust the phase shift seen by the element wit the goal of being able to remove the phase shifting devices from the antenna and replace...

  12. OpenShift Workshop

    CERN Multimedia

    CERN. Geneva; Rodriguez Peon, Alberto

    2017-01-01

    Workshop to introduce developers to the OpenShift platform available at CERN. Several use cases will be shown, including deploying an existing application into OpenShift. We expect attendees to realize about OpenShift features and general architecture of the service.

  13. A new plastic scintillator with large Stokes shift

    International Nuclear Information System (INIS)

    Destruel, P.; Taufer, M.

    1989-01-01

    We have developed a new plastic scintillator with the novel characteristic of highly localized light emission; scintillation and wavelength shifting take place within a few tens of micrometers of the primary ionization. The new scintillator consists of a scintillating polymer base [polyvinyl toluene (PVT) or polystyrene (PS)] doped with a single wavelength shifter, 1-phenyl-3-mesityl-2-pyrazoline (PMP), which has an exceptionally large Stokes shift and therefore a comparatively small self-absorption of its emitted light. In other characteristics (e.g. scintillation efficiency and decay time) the performance of the new scintillator is similar to a good quality commercial plastic scintillator such as NE110. (orig.)

  14. Solar Observations at Submillimeter Wavelengths

    Science.gov (United States)

    Kaufmann, P.

    We review earlier to recent observational evidences and theoretical motivations leading to a renewed interest to observe flares in the submillimeter (submm) - infrared (IR) range of wavelengths. We describe the new solar dedicated submillimeter wave telescope which began operations at El Leoncito in the Argentina Andes: the SST project. It consists of focal plane arrays of two 405 GHz and four 212 GHz radiometers placed in a 1.5-m radome-enclosed Cassegrain antenna, operating simultaneously with one millisecond time resolution. The first solar events analyzed exhibited the onset of rapid submm-wave spikes (100-300 ms), well associated to other flare manifestations, especially at X-rays. The spikes positions were found scattered over the flaring source by tens of arcseconds. For one event an excellent association was found between the gamma-ray emission time profile and the rate of occurrence of submm-wave rapid spikes. The preliminary results favour the idea that bulk burst emissions are a response to numerous fast energetic injections, discrete in time, produced at different spatial positions over the flaring region. Coronal mass ejections were associated to the events studied. Their trajectories extrapolated to the solar surface appear to correspond to the onset time of the submm-wave spikes, which might represent an early signature of the CME's initial acceleration process.

  15. Effective wavelength calibration for moire fringe projection

    International Nuclear Information System (INIS)

    Purcell, Daryl; Davies, Angela; Farahi, Faramarz

    2006-01-01

    The fringe patterns seen when using moire instruments are similar to the patterns seen in traditional interferometry but differ in the spacing between consecutive fringes. In traditional interferometry, the spacing is constant and related to the wavelength of the source. In moire fringe projection, the spacing (the effective wavelength) may not be constant over the field of view and the spacing depends on the system geometry. In these cases, using a constant effective wavelength over the field of view causes inaccurate surface height measurements. We examine the calibration process of the moirefringe projection measurement, which takes this varying wavelength into account to produce a pixel-by-pixel wavelength map. The wavelength calibration procedure is to move the object in the out-of-plane direction a known distance until every pixel intensity value goes through at least one cycle. A sinusoidal function is then fit to the data to extract the effective wavelength pixel by pixel, yielding an effective wavelength map. A calibrated step height was used to validate the effective wavelength map with results within 1% of the nominal value of the step height. The error sources that contributed to the uncertainty in determining the height of the artifact are also investigated

  16. Understanding and controlling chromaticity shift in LED devices

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Lynn; Mills, Karmann; Lamvik, Michael; Perkins, Curtis; Bobashev, Georgiy; Young, Joseph; Yaga, Robert; Johnson, Cortina

    2017-05-30

    Chromaticity shift in light-emitting diode (LED) devices arises from multiple mechanisms, and at least five different chromaticity shift modes (CSMs) have been identified to date. This paper focuses on the impacts of irreversible phosphor degradation as a cause of chromaticity shifts in LED devices. The nitride phosphors used to produce warm white LEDs are especially vulnerable to degradation due to thermal and chemical effects such as reactions with oxygen and water. As a result, LED devices utilizing these phosphors were found to undergo either a green shift or, less commonly, a red shift depending on the phosphor mix in the LED devices. These types of chromaticity shifts are classified as CSM-2 (green shift) and CSM-5 (red shift). This paper provides an overview of the kinetic processes responsible for green and red chromaticity shifts along with examples from accelerated stress testing of 6” downlights. Both CSMs appear to proceed through analogous mechanisms that are initiated at the surface of the phosphor. A green shift is produced by the surface oxidation of the nitride phosphor that changes the emission profile to lower wavelengths. As the surface oxidation reaction proceeds, reactant limitations slow the rate and bulk oxidation processes become more prevalent. We found that a red chromaticity shift arises from quenching of the green phosphor, also possibly due to surface reactions of oxygen, which shift the emission chromaticity in the red direction. In conclusion, we discuss the implications of these findings on projecting chromaticity.

  17. PROTECTIVE COATINGS OF FIBER BRAGG GRATING FOR MINIMIZING OF MECHANICAL IMPACT ON ITS WAVELENGTH CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    A. S. Munko

    2015-03-01

    Full Text Available The paper deals with the scheme for the study of the Bragg wavelength shift dependence on the applied tensile force. Samples of fiber Bragg gratings with different coatings have been studied: the restored acrylate coating, the heatshrinkable fusion splice protection sleeve without metal rod, the heat-shrinkable fusion splice protection sleeve with a metal rod, the metal capillary, polyvinylchloride tube. For different coatings of diffractive structure, dependences of wavelength shift for the Bragg grating resonance have been obtained on the tensile strength applied to the ends of an optical fiber. It was determined that the studied FBG coatings give the possibility to reduce the mechanical impact on the Bragg wavelength shift for 1.1-15 times as compared to an uncoated waveguide. The most effective version of coated fiber Bragg grating is the heatshrinkable fusion splice protection sleeve with a metal rod. When the force (equal to 6 N is applied to the 100 mm optical fiber area with the inscribed diffractive structure, the Bragg wavelength shift is 7.5 nm for the unprotected sample and 0.5 nm for the one coated with the heat-shrinkable fusion splice protection sleeve.

  18. On-chip microparticle detection and sizing using a dual-wavelength waveguide laser

    NARCIS (Netherlands)

    Bernhardi, Edward H.; van der Werf, Kees O; Hollink, Anton J F; Worhoff, Kerstin; De Ridder, Rene M.; Subramaniam, Vinod; Pollnau, Markus

    2013-01-01

    An integrated intra-laser-cavity microparticle sensor based on a dual-phase-shift, dual-wavelength distributed-feedback channel waveguide laser in Al2O3:Yb3+ is presented. Real-time detection and accurate size measurement of single microparticles with diameters ranging between 1 μm and 20 μm are

  19. On-chip microparticle detection and sizing using a dual-wavelength waveguide laser

    NARCIS (Netherlands)

    Bernhardi, Edward; van der Werf, Kees; Hollink, Anton; Worhoff, Kerstin; de Ridder, R.M.; Subramaniam, Vinod; Pollnau, Markus

    An integrated intra-laser-cavity microparticle sensor based on a dual-phase-shift, dual-wavelength distributed-feedback channel waveguide laser in ytterbium-doped aluminium oxide is presented. Single micro-particles with diameters ranging between 1 μm and 20 μm are detected.

  20. Wavelength scaling of laser plasma coupling

    International Nuclear Information System (INIS)

    Kruer, W.L.

    1983-01-01

    The use of shorter wavelength laser light both enhances collisional absorption and reduces deleterious collective plasma effects. Coupling processes which can be important in reactor-size targets are briefly reviewed. Simple estimates are presented for the intensity-wavelength regime in which collisional absorption is high and collective effects are minimized

  1. A criticism of big bang cosmological models based on interpretation of the red shift

    Energy Technology Data Exchange (ETDEWEB)

    Kierein, J.W. (Ball Aerospace Systems Div., Boulder, CO (USA))

    1988-08-01

    The interaction of light with the intergalactic plasma produces the Hubble red shift versus distance relationship. This interaction also produces an isotopic long wavelength background radiation from the plasma. Intrinsic red shifts in quasars and other objects are similarly explained, showing why they are exceptions to Hubble's law. Because the red shift is not doppler-shifted, big bang cosmological models should be replaced with static models. (author).

  2. Choice Shifts in Groups

    OpenAIRE

    Kfir Eliaz; Debraj Ray

    2004-01-01

    The phenomenon of "choice shifts" in group decision-making is fairly ubiquitous in the social psychology literature. Faced with a choice between a ``safe" and ``risky" decision, group members appear to move to one extreme or the other, relative to the choices each member might have made on her own. Both risky and cautious shifts have been identified in different situations. This paper demonstrates that from an individual decision-making perspective, choice shifts may be viewed as a systematic...

  3. Implementing OpenShift

    CERN Document Server

    Miller, Adam

    2013-01-01

    A standard tutorial-based approach to using OpenShift and deploying custom or pre-built web applications to the OpenShift Online cloud.This book is for software developers and DevOps alike who are interested in learning how to use the OpenShift Platform-as-a-Service for developing and deploying applications, how the environment works on the back end, and how to deploy their very own open source Platform-as-a-Service based on the upstream OpenShift Origin project.

  4. Insomnia in shift work.

    Science.gov (United States)

    Vallières, Annie; Azaiez, Aïda; Moreau, Vincent; LeBlanc, Mélanie; Morin, Charles M

    2014-12-01

    Shift work disorder involves insomnia and/or excessive sleepiness associated with the work schedule. The present study examined the impact of insomnia on the perceived physical and psychological health of adults working on night and rotating shift schedules compared to day workers. A total of 418 adults (51% women, mean age 41.4 years), including 51 night workers, 158 rotating shift workers, and 209 day workers were selected from an epidemiological study. An algorithm was used to classify each participant of the two groups (working night or rotating shifts) according to the presence or absence of insomnia symptoms. Each of these individuals was paired with a day worker according to gender, age, and income. Participants completed several questionnaires measuring sleep, health, and psychological variables. Night and rotating shift workers with insomnia presented a sleep profile similar to that of day workers with insomnia. Sleep time was more strongly related to insomnia than to shift work per se. Participants with insomnia in the three groups complained of anxiety, depression, and fatigue, and reported consuming equal amounts of sleep-aid medication. Insomnia also contributed to chronic pain and otorhinolaryngology problems, especially among rotating shift workers. Work productivity and absenteeism were more strongly related to insomnia. The present study highlights insomnia as an important component of the sleep difficulties experienced by shift workers. Insomnia may exacerbate certain physical and mental health problems of shift workers, and impair their quality of life. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. The dynamics of interacting nonlinearities governing long wavelength driftwave turbulence

    International Nuclear Information System (INIS)

    Newman, D.E.

    1993-09-01

    Because of the ubiquitous nature of turbulence and the vast array of different systems which have turbulent solutions, the study of turbulence is an area of active research. Much present day understanding of turbulence is rooted in the well established properties of homogeneous Navier-Stokes turbulence, which, due to its relative simplicity, allows for approximate analytic solutions. This work examines a group of turbulent systems with marked differences from Navier-Stokes turbulence, and attempts to quantify some of their properties. This group of systems represents a variety of drift wave fluctuations believed to be of fundamental importance in laboratory fusion devices. From extensive simulation of simple local fluid models of long wavelength drift wave turbulence in tokamaks, a reasonably complete picture of the basic properties of spectral transfer and saturation has emerged. These studies indicate that many conventional notions concerning directions of cascades, locality and isotropy of transfer, frequencies of fluctuations, and stationarity of saturation are not valid for moderate to long wavelengths. In particular, spectral energy transfer at long wavelengths is dominated by the E x B nonlinearity, which carries energy to short scale in a manner that is highly nonlocal and anisotropic. In marked contrast to the canonical self-similar cascade dynamics of Kolmogorov, energy is efficiently passed between modes separated by the entire spectrum range in a correlation time. At short wavelengths, transfer is dominated by the polarization drift nonlinearity. While the standard dual cascade applies in this subrange, it is found that finite spectrum size can produce cascades that are reverse directed and are nonconservative in enstrophy and energy similarity ranges. In regions where both nonlinearities are important, cross-coupling between the nolinearities gives rise to large no frequency shifts as well as changes in the spectral dynamics

  6. Stokes shift spectroscopy for breast cancer diagnosis

    Science.gov (United States)

    Jeyasingh, Ebenezar; Prakashrao, Aruna; Singaravelu, Ganesan

    2010-02-01

    The objective of this study is to assess the diagnostic potential of stokes shift (SS) spectroscopy (SSS) for normal and different pathological breast tissues such as fibroadenoma and infiltrating ductal carcinoma. The SS spectra is measured by simultaneously scanning both the excitation and emission wavelengths while keeping a fixed wavelength interval Δλ=20 nm between them. Characteristic, highly resolved peaks and significant spectral differences between normal and different pathological breast tissues were observed. The SS spectra of normal and different pathological breast tissues shows the distinct peaks around 300, 350, 450, 500 and 600 nm may be attributed to tryptophan, collagen, NADH, flavin and porphyrin respectively. Using SSS technique one can obtain all the key fluorophores in a single scan and hence they can be targeted as a tumor markers in this study. In order to quantify the altered spectral differences between normal and different pathological breast tissues are verified by different ratio parameters.

  7. Shifted Independent Component Analysis

    DEFF Research Database (Denmark)

    Mørup, Morten; Madsen, Kristoffer Hougaard; Hansen, Lars Kai

    2007-01-01

    Delayed mixing is a problem of theoretical interest and practical importance, e.g., in speech processing, bio-medical signal analysis and financial data modelling. Most previous analyses have been based on models with integer shifts, i.e., shifts by a number of samples, and have often been carried...

  8. Homogeneous bilateral block shifts

    Indian Academy of Sciences (India)

    Douglas class were classified in [3]; they are unilateral block shifts of arbitrary block size (i.e. dim H(n) can be anything). However, no examples of irreducible homogeneous bilateral block shifts of block size larger than 1 were known until now.

  9. OpenShift cookbook

    CERN Document Server

    Gulati, Shekhar

    2014-01-01

    If you are a web application developer who wants to use the OpenShift platform to host your next big idea but are looking for guidance on how to achieve this, then this book is the first step you need to take. This is a very accessible cookbook where no previous knowledge of OpenShift is needed.

  10. Short wavelength FELs using the SLAC linac

    International Nuclear Information System (INIS)

    Winick, H.; Bane, K.; Boyce, R.

    1993-08-01

    Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops

  11. Josephson shift registers

    International Nuclear Information System (INIS)

    Przybysz, J.X.

    1989-01-01

    This paper gives a review of Josephson shift register circuits that were designed, fabricated, or tested, with emphasis on work in the 1980s. Operating speed is most important, since it often limits system performance. Older designs used square-wave clocks, but most modern designs use offset sine waves, with either two or three phases. Operating margins and gate bias uniformity are key concerns. The fastest measured Josephson shift register operated at 2.3 GHz, which compares well with a GaAs shift register that consumes 250 times more power. The difficulties of high-speed testing have prevented many Josephson shift registers from being operated at their highest speeds. Computer simulations suggest that 30-GHz operation is possible with current Nb/Al 2 O 3 /Nb technology. Junctions with critical current densities near 10 kA/cm 2 would make 100-GHz shift registers feasible

  12. Multi-wavelength lasers using AWGs

    NARCIS (Netherlands)

    Besten, den J.H.

    2003-01-01

    Multiwavelength lasers using AWGs can be used as digitally tunable lasers with simple channel selection, and for generating multiple wavelengths simultanously. In this paper a number of different configurations is reviewed.

  13. Wavelength mismatch effect in electromagnetically induced absorption

    Energy Technology Data Exchange (ETDEWEB)

    Bharti, Vineet [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Wasan, Ajay [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Natarajan, Vasant [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

    2016-07-15

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch—near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers. - Highlights: • Wavelength mismatch effect is investigated in electromagnetically induced absorption (EIA). • An experimental realization of 4-level vee + ladder system using energy levels of rubidium atom is presented. • EIA resonances are studied under different conditions of wavelength mismatch. • Possibility of observation of EIA using Rydberg states excited with diode lasers.

  14. Wavelength mismatch effect in electromagnetically induced absorption

    International Nuclear Information System (INIS)

    Bharti, Vineet; Wasan, Ajay; Natarajan, Vasant

    2016-01-01

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch—near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers. - Highlights: • Wavelength mismatch effect is investigated in electromagnetically induced absorption (EIA). • An experimental realization of 4-level vee + ladder system using energy levels of rubidium atom is presented. • EIA resonances are studied under different conditions of wavelength mismatch. • Possibility of observation of EIA using Rydberg states excited with diode lasers.

  15. Plasmon Geometric Phase and Plasmon Hall Shift

    Science.gov (United States)

    Shi, Li-kun; Song, Justin C. W.

    2018-04-01

    The collective plasmonic modes of a metal comprise a simple pattern of oscillating charge density that yields enhanced light-matter interaction. Here we unveil that beneath this familiar facade plasmons possess a hidden internal structure that fundamentally alters its dynamics. In particular, we find that metals with nonzero Hall conductivity host plasmons with an intricate current density configuration that sharply departs from that of ordinary zero Hall conductivity metals. This nontrivial internal structure dramatically enriches the dynamics of plasmon propagation, enabling plasmon wave packets to acquire geometric phases as they scatter. At boundaries, these phases accumulate allowing plasmon waves that reflect off to experience a nonreciprocal parallel shift. This plasmon Hall shift, tunable by Hall conductivity as well as plasmon wavelength, displaces the incident and reflected plasmon trajectories and can be readily probed by near-field photonics techniques. Anomalous plasmon geometric phases dramatically enrich the nanophotonics toolbox, and yield radical new means for directing plasmonic beams.

  16. Nurses' shift reports

    DEFF Research Database (Denmark)

    Buus, Niels; Hoeck, Bente; Hamilton, Bridget Elizabeth

    2017-01-01

    AIMS AND OBJECTIVES: To identify reporting practices that feature in studies of nurses' shift reports across diverse nursing specialities. The objectives were to perform an exhaustive systematic literature search and to critically review the quality and findings of qualitative field studies...... of nurses' shift reports. BACKGROUND: Nurses' shift reports are routine occurrences in healthcare organisations that are viewed as crucial for patient outcomes, patient safety and continuity of care. Studies of communication between nurses attend primarily to 1:1 communication and analyse the adequacy...... and accuracy of patient information and feature handovers at the bedside. Still, verbal reports between groups of nurses about patients are commonplace. Shift reports are obvious sites for studying the situated accomplishment of professional nursing at the group level. This review is focused exclusively...

  17. Shift Verification and Validation

    Energy Technology Data Exchange (ETDEWEB)

    Pandya, Tara M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Evans, Thomas M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Davidson, Gregory G [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnson, Seth R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Godfrey, Andrew T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-07

    This documentation outlines the verification and validation of Shift for the Consortium for Advanced Simulation of Light Water Reactors (CASL). Five main types of problems were used for validation: small criticality benchmark problems; full-core reactor benchmarks for light water reactors; fixed-source coupled neutron-photon dosimetry benchmarks; depletion/burnup benchmarks; and full-core reactor performance benchmarks. We compared Shift results to measured data and other simulated Monte Carlo radiation transport code results, and found very good agreement in a variety of comparison measures. These include prediction of critical eigenvalue, radial and axial pin power distributions, rod worth, leakage spectra, and nuclide inventories over a burn cycle. Based on this validation of Shift, we are confident in Shift to provide reference results for CASL benchmarking.

  18. Molecular Electronic Shift Registers

    Science.gov (United States)

    Beratan, David N.; Onuchic, Jose N.

    1990-01-01

    Molecular-scale shift registers eventually constructed as parts of high-density integrated memory circuits. In principle, variety of organic molecules makes possible large number of different configurations and modes of operation for such shift-register devices. Several classes of devices and implementations in some specific types of molecules proposed. All based on transfer of electrons or holes along chains of repeating molecular units.

  19. Lattice-induced nonadiabatic frequency shifts in optical lattice clocks

    International Nuclear Information System (INIS)

    Beloy, K.

    2010-01-01

    We consider the frequency shift in optical lattice clocks which arises from the coupling of the electronic motion to the atomic motion within the lattice. For the simplest of three-dimensional lattice geometries this coupling is shown to affect only clocks based on blue-detuned lattices. We have estimated the size of this shift for the prospective strontium lattice clock operating at the 390-nm blue-detuned magic wavelength. The resulting fractional frequency shift is found to be on the order of 10 -18 and is largely overshadowed by the electric quadrupole shift. For lattice clocks based on more complex geometries or other atomic systems, this shift could potentially be a limiting factor in clock accuracy.

  20. Method and apparatus for simultaneously measuring a plurality of spectral wavelengths present in electromagnetic radiation

    Science.gov (United States)

    Buican, Tudor N.; Martin, John C.

    1990-01-01

    An apparatus and method simultaneously measures a plurality of spectral wavelengths present in electromagnetic radiation. A modulatable birefringent optical element is employed to divide a polarized light beam into two components, thereby producing a phase difference in two resulting light beams such that the two beams can be made to interfere with one another when recombined, the interference pattern providing the wavelength information required for the analysis of the incident light. The interferometer thus created performs in a similar manner to a Michelson interferometer, but with no moving parts, and with a resolution dependent on the degree of phase shift introduced by the modulator.

  1. Ultra-high-speed wavelength conversion in a silicon photonic chip

    DEFF Research Database (Denmark)

    Hu, Hao; Ji, Hua; Galili, Michael

    2011-01-01

    We have successfully demonstrated all-optical wavelength conversion of a 640-Gbit/s line-rate return-to-zero differential phase-shift keying (RZ-DPSK) signal based on low-power four wave mixing (FWM) in a silicon photonic chip with a switching energy of only ~110 fJ/bit. The waveguide dispersion...... of the silicon nanowire is nano-engineered to optimize phase matching for FWM and the switching power used for the signal processing is low enough to reduce nonlinear absorption from twophoton- absorption (TPA). These results demonstrate that high-speed wavelength conversion is achievable in silicon chips...

  2. Wavelength Conversion of DP-QPSK Signals in a Silicon Polarization Diversity Circuit

    DEFF Research Database (Denmark)

    Vukovic, Dragana; Schroeder, Jochen; Ding, Yunhong

    2015-01-01

    Multichannel wavelength conversion is experimentally demonstrated for high-speed 128 Gb/s dual-polarization quadrature phase-shift keying signals using four-wave mixing in a polarization diversity circuit with silicon nanowires as nonlinear elements. The wavelength conversion performance is inves...... is investigated for both single-and three-channel input signals, showing quality factors well >9.8 dB (corresponding to bit-error-ratios better than 10(-3)) and with a negligible power penalty compared with the back-to-back case....

  3. Wavelength dependence of the Brillouin spectral width of boron doped germanosilicate optical fibers.

    Science.gov (United States)

    Law, Pi-Cheng; Dragic, Peter D

    2010-08-30

    Boron co-doped germanosilicate fibers are investigated via the Brillouin light scattering technique using two wavelengths, 1534 nm and 1064 nm. Several fibers are investigated, including four drawn from the same preform but at different draw temperatures. The Stokes' shifts and the Brillouin spectral widths are found to increase with increasing fiber draw temperature. A frequency-squared law has adequately described the wavelength dependence of the Brillouin spectral width of conventional Ge-doped fibers. However, it is found that unlike conventional Ge-doped fibers these fibers do not follow the frequency-squared law. This is explained through a frequency-dependent dynamic viscosity that modifies this law.

  4. Soliton-based ultrafast multi-wavelength nonlinear switching in dual-core photonic crystal fibre

    International Nuclear Information System (INIS)

    Stajanca, P; Pysz, D; Michalka, M; Bugar, I; Andriukaitis, G; Balciunas, T; Fan, G; Baltuska, A

    2014-01-01

    Systematic experimental study of ultrafast multi-wavelength all-optical switching performance in a dual-core photonic crystal fibre is presented. The focus is on nonlinearly induced switching between the two output ports at non-excitation wavelengths, which are generated during nonlinear propagation of femtosecond pulses in the anomalous dispersion region of a dual-core photonic crystal fibre made of multicomponent glass. Spatial and spectral characteristics of the fibre output radiation were measured separately for both fibre cores under various polarization and intensity conditions upon selective, individual excitation of each fibre core. Polarization-controlled nonlinear switching performance at multiple non-excitation wavelengths was demonstrated in the long-wavelength optical communication bands and beyond. Depending on the input pulse polarization, narrowband switching operation at 1560 nm and 1730 nm takes place with double core extinction ratio contrasts of 9 dB and 14.5 dB, respectively. Moreover, our approach allows switching with simultaneous wavelength shift from 1650 to 1775 nm with extinction ratio contrast larger than 18 dB. In addition, non-reciprocal behaviour of the soliton fission process under different fibre core excitations was observed and its effect on the multi-wavelength nonlinear switching performance was explained, taking into account the slight dual-core structure asymmetry. The obtained results represent ultrafast all-optical switching with an extended dimension of wavelength shift, controllable with both the input radiation intensity and the polarization by simple propagation along a 14 mm long fibre. (paper)

  5. Design of a muon tomography system with a plastic scintillator and wavelength-shifting fiber arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Woo Jin; Kim, Hyun-Il; An, Su Jung; Lee, Chae Young [Department of Radiological Science, College of Health Science, Yonsei University, Wonju 220-710 (Korea, Republic of); Baek, Cheol-Ha [Department of Radiological Science, Dongseo University, Busan 617-716 (Korea, Republic of); Chung, Yong Hyun, E-mail: ychung@yonsei.ac.kr [Department of Radiological Science, College of Health Science, Yonsei University, Wonju 220-710 (Korea, Republic of)

    2013-12-21

    Recently, monitoring nuclear materials to avoid nuclear terrorism has become an important area of national security. It can be difficult to detect gamma rays from nuclear material because they are easily shielded by shielding material. Muon tomography using multiple -Coulomb scattering derived from muons can be utilized to detect special nuclear materials (SNMs) such as uranium-235 and plutonium-239. We designed a muon tomography system composed of four detector modules. The incident and scattered muon tracks can be calculated by two top and two bottom detectors, respectively. 3D tomographic images are obtained by extracting the crossing points of muon tracks with a point-of-closest-approach algorithm. The purpose of this study was to optimize the muon tomography system using Monte Carlo simulation code. The effects of the geometric parameters of the muon tomography system on material Z-discrimination capability were simulated and evaluated.

  6. Wavelength converter placement for different RWA algorithms in wavelength-routed all-optical networks

    Science.gov (United States)

    Chu, Xiaowen; Li, Bo; Chlamtac, Imrich

    2002-07-01

    Sparse wavelength conversion and appropriate routing and wavelength assignment (RWA) algorithms are the two key factors in improving the blocking performance in wavelength-routed all-optical networks. It has been shown that the optimal placement of a limited number of wavelength converters in an arbitrary mesh network is an NP complete problem. There have been various heuristic algorithms proposed in the literature, in which most of them assume that a static routing and random wavelength assignment RWA algorithm is employed. However, the existing work shows that fixed-alternate routing and dynamic routing RWA algorithms can achieve much better blocking performance. Our study in this paper further demonstrates that the wavelength converter placement and RWA algorithms are closely related in the sense that a well designed wavelength converter placement mechanism for a particular RWA algorithm might not work well with a different RWA algorithm. Therefore, the wavelength converter placement and the RWA have to be considered jointly. The objective of this paper is to investigate the wavelength converter placement problem under fixed-alternate routing algorithm and least-loaded routing algorithm. Under the fixed-alternate routing algorithm, we propose a heuristic algorithm called Minimum Blocking Probability First (MBPF) algorithm for wavelength converter placement. Under the least-loaded routing algorithm, we propose a heuristic converter placement algorithm called Weighted Maximum Segment Length (WMSL) algorithm. The objective of the converter placement algorithm is to minimize the overall blocking probability. Extensive simulation studies have been carried out over three typical mesh networks, including the 14-node NSFNET, 19-node EON and 38-node CTNET. We observe that the proposed algorithms not only outperform existing wavelength converter placement algorithms by a large margin, but they also can achieve almost the same performance comparing with full wavelength

  7. Phase and fringe order determination in wavelength scanning interferometry.

    Science.gov (United States)

    Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel

    2016-04-18

    A method to obtain unambiguous surface height measurements using wavelength scanning interferometry with an improved repeatability, comparable to that obtainable using phase shifting interferometry, is reported. Rather than determining the conventional fringe frequency-derived z height directly, the method uses the frequency to resolve the fringe order ambiguity, and combine this information with the more accurate and repeatable fringe phase derived z height. A theoretical model to evaluate the method's performance in the presence of additive noise is derived and shown to be in good agreement with experiments. The measurement repeatability is improved by a factor of ten over that achieved when using frequency information alone, reaching the sub-nanometre range. Moreover, the z-axis non-linearity (bleed-through or ripple error) is reduced by a factor of ten. These order of magnitude improvements in measurement performance are demonstrated through a number of practical measurement examples.

  8. Multi-wavelength approach towards on-product overlay accuracy and robustness

    Science.gov (United States)

    Bhattacharyya, Kaustuve; Noot, Marc; Chang, Hammer; Liao, Sax; Chang, Ken; Gosali, Benny; Su, Eason; Wang, Cathy; den Boef, Arie; Fouquet, Christophe; Huang, Guo-Tsai; Chen, Kai-Hsiung; Cheng, Kevin; Lin, John

    2018-03-01

    Success of diffraction-based overlay (DBO) technique1,4,5 in the industry is not just for its good precision and low toolinduced shift, but also for the measurement accuracy2 and robustness that DBO can provide. Significant efforts are put in to capitalize on the potential that DBO has to address measurement accuracy and robustness. Introduction of many measurement wavelength choices (continuous wavelength) in DBO is one of the key new capabilities in this area. Along with the continuous choice of wavelengths, the algorithms (fueled by swing-curve physics) on how to use these wavelengths are of high importance for a robust recipe setup that can avoid the impact from process stack variations (symmetric as well as asymmetric). All these are discussed. Moreover, another aspect of boosting measurement accuracy and robustness is discussed that deploys the capability to combine overlay measurement data from multiple wavelength measurements. The goal is to provide a method to make overlay measurements immune from process stack variations and also to report health KPIs for every measurement. By combining measurements from multiple wavelengths, a final overlay measurement is generated. The results show a significant benefit in accuracy and robustness against process stack variation. These results are supported by both measurement data as well as simulation from many product stacks.

  9. An optimized prototype of electromagnetic calorimeter for the SoLID project at Jefferson Lab

    Science.gov (United States)

    Shen, C.; Wang, Y.; Xiao, D.; Han, D.; Zou, Z.; Li, Y.; Zheng, X.; Chen, J.

    2018-02-01

    A shashlik-type electromagnetic calorimeter will be produced in Hall A of Jefferson Laboratory for the Solenoidal Large Intensity Device (SoLID). Wavelength-shifting (WLS) fibers and clear fibers will be used as the light guide part of the calorimeter. The blue light from scintillators is converted into green light by WLS fibers and is carried out to the back of the calorimeters for readout. Since the magnetic field of SoLID reaches about 1.5 T behind the calorimeters, the design is to use clear fibers to further guide the light out of the solenoid for readout by PMTs. Therefore, it is important to study the perfomance of WLS and clear fibers. This paper describes a comparative test of two different WLS fibers and a light attenuation test for a clear fiber. The results show that the performance of the two WLS fibers is the same under large curvature bending, and that the bending has no effect on the light transmission through the clear fiber. In addition, a comparison test for two fiber end-face reflective materials is also reported. It reveals that the use of silver ink as a reflective material can increase the light yield by 30%. Thereby, an optimized prototype based on the above experimental results was built and the basic performance was tested.

  10. Wavelength division multiplexing a practical engineering guide

    CERN Document Server

    Grobe, Klaus

    2013-01-01

    In this book, Optical Wavelength Division Multiplexing (WDM) is approached from a strictly practical and application-oriented point of view. Based on the characteristics and constraints of modern fiber-optic components, transport systems and fibers, the text provides relevant rules of thumb and practical hints for technology selection, WDM system and link dimensioning, and also for network-related aspects such as wavelength assignment and resilience mechanisms. Actual 10/40 Gb/s WDM systems are considered, and a preview of the upcoming 100 Gb/s systems and technologies for even higher bit rate

  11. Short wavelength sources and atoms and ions

    International Nuclear Information System (INIS)

    Kennedy, E.T.

    2008-01-01

    The interaction of ionizing radiation with atoms and ions is a key fundamental process. Experimental progress has depended in particular on the development of short wavelength light sources. Laser-plasma and synchrotron sources have been exploited for several decades and most recently the development of short wavelength Free Electron Laser (FEL) sources is revolutionizing the field. This paper introduces laser plasma and synchrotron sources through examples of their use in studies of the interaction of ionizing radiation with atoms and ions, ranging from few-electron atomic and ionic systems to the many-electron high atomic number actinides. The new FEL source (FLASH) at DESY is introduced. (author)

  12. Wavelength tunable ultrafast fiber laser via reflective mirror with taper structure.

    Science.gov (United States)

    Fang, Li; Huang, Chuyun; Liu, Ting; Gogneau, Noelle; Bourhis, Eric; Gierak, Jacques; Oudar, Jean-Louis

    2016-12-20

    Laser sources with a controllable flexible wavelength have found widespread applications in optical fiber communication, optical sensing, and microscopy. Here, we report a tunable mode-locked fiber laser using a graphene-based saturable absorber and a tapered mirror as an end mirror in the cavity. The phase layer in the mirror is precisely etched by focused ion beam (FIB) milling technology, and the resonant wavelength of the mirror shifts correspond to the different etch depths. By scanning the tapered mirror mechanically, the center wavelength of a mode-locked fiber laser can be continuously tuned from 1562 to 1532 nm, with a pulse width in the sub-ps level and repetition rate of 27 MHz.

  13. Strain induced tunable wavelength filters based on flexible polymer waveguide Bragg reflector.

    Science.gov (United States)

    Kim, Kyung-Jo; Seo, Jun-Kyu; Oh, Min-Cheol

    2008-02-04

    A tunable wavelength filter is demonstrated by imposing a strain on a polymeric Bragg reflection waveguide fabricated on a flexible substrate. The highly elastic property of flexible polymer device enables much wider tuning than the silica fiber. To produce a uniform grating pattern on a flexible plastic substrate, a post lift-off process along with an absorbing layer is incorporated. The flexible Bragg reflector shows narrow bandwidth, which is convincing the uniformity of the grating structure fabricated on plastic film. By stretching the flexible polymer device, the Bragg reflection wavelength is tuned continuously up to 45 nm for the maximum strain of 31,690 muepsilon, which is determined by the elastic expansion limit of waveguide polymer. From the linear wavelength shift proportional to the strain, the photoelastic coefficient of the ZPU polymer is found.

  14. Simulation of simultaneously obtaining ocean temperature and salinity using dual-wavelength Brillouin lidar

    International Nuclear Information System (INIS)

    Yu, Yin; Ma, Yong; Li, Hao; Huang, Jun; Fang, Yu; Liang, Kun; Zhou, Bo

    2014-01-01

    A method for simultaneously obtaining the ocean temperature and salinity based on dual-wavelength Brillouin lidar is proposed in this letter. On the basis of the relationships between the temperature and salinity and the Brillouin shifts, a retrieval model for retrieving the temperature and salinity is established. By using the retrieval model, the ocean temperature and salinity can be simultaneously obtained through the Brillouin shifts. Simulation based on dual-wavelength Brillouin lidar is also carried out for verification of the accuracy of the retrieval model. Results show that the errors of the retrieval model for temperature and salinity are ±0.27 °C and ±0.33‰. (letter)

  15. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Sherwood, D.G.; Wilson, J.F.; Salton, R.B.; Fensterer, H.F.

    1981-01-01

    A mechanical spectral shift reactor comprises apparatus for inserting and withdrawing water displacer elements from the reactor core for selectively changing the water-moderator volume in the core thereby changing the reactivity of the core. The apparatus includes drivemechanisms for moving the displacer elements relative to the core and guide mechanisms for guiding the displayer rods through the reactor vessel

  16. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Sherwood, D.G.; Wilson, J.F.; Salton, R.B.; Fensterer, H.F.

    1982-01-01

    A mechanical spectral shift reactor comprises apparatus for inserting and withdrawing water displacer elements from the reactor core for selectively changing the water-moderator volume in the core thereby changing the reactivity of the core. The apparatus includes drive mechanisms for moving the displacer elements relative to the core and guide mechanisms for guiding the displacer rods through the reactor vessel. (author)

  17. Topology Optimization of Sub-Wavelength Antennas

    DEFF Research Database (Denmark)

    Erentok, Aycan; Sigmund, Ole

    2011-01-01

    We propose a topology optimization strategy for the systematic design of a three-dimensional (3D), conductor-based sub-wavelength antenna. The post-processed finite-element (FE) models of the optimized structure are shown to be self-resonant, efficient and exhibit distorted omnidirectional...

  18. Characterization of ethanol concentrations at ultraviolet wavelength ...

    African Journals Online (AJOL)

    This paper presents the measurement of optical absorption spectrum for different concentrations of ethanol at ultraviolet wavelength. Ethanol absorption spectrum was measured using portable spectroscopy setup from Avantes. It consists of Balanced Deuterium Halogen light source and spectrometer. The light source can ...

  19. Smart wavelength meter for integrated photonics

    NARCIS (Netherlands)

    Benelajla, Meryem; Taballione, Caterina; Boller, Klaus J.

    2017-01-01

    Thermally tunable SiN waveguide microring resonators in connection with neural network readout algorithms appear promising for use as integrated optical wavelength meters. So far, we have observed long-term reliability and a temperature immunity of the readout across several degrees of ambient

  20. An automated wavelength selection for flame spectroscopy

    International Nuclear Information System (INIS)

    Hurteau, M.; Mislan, J.P.; Ashley, R.W.

    1976-01-01

    A simple electro-mechanical programming system is described for use with a flame spectrophotometer. Its application for automated sequential multi-element analysis is illustrated. Reproducibility of wavelength settings are within +-0.5 A. Precision and sensitivities are at least as good as those obtained for single element determinations. (author)

  1. Alien wavelength modeling tool and field trial

    DEFF Research Database (Denmark)

    Sambo, N.; Sgambelluri, A.; Secondini, M.

    2015-01-01

    A modeling tool is presented for pre-FEC BER estimation of PM-QPSK alien wavelength signals. A field trial is demonstrated and used as validation of the tool's correctness. A very close correspondence between the performance of the field trial and the one predicted by the modeling tool has been...

  2. Two-wavelength spatial-heterodyne holography

    Science.gov (United States)

    Hanson, Gregory R.; Bingham, Philip R.; Simpson, John T.; Karnowski, Thomas P.; Voelkl, Edgar

    2007-12-25

    Systems and methods are described for obtaining two-wavelength differential-phase holograms. A method includes determining a difference between a filtered analyzed recorded first spatially heterodyne hologram phase and a filtered analyzed recorded second spatially-heterodyned hologram phase.

  3. Angular characteristics of a multimode fibre surface plasmon resonance sensor under wavelength interrogation

    International Nuclear Information System (INIS)

    Tan, Zhixin; Hao, Xin; Li, Xuejin; Chen, Yuzhi; Hong, Xueming; Fan, Ping

    2016-01-01

    In this paper the angular characteristics of a multimode fibre SPR sensor are theoretically investigated. By separating the contributions of beams incident at different angles, a compact model is presented to predict the shift of the resonance wavelength with respect to the angle and the environmental refractive index. The result suggests that the performance of conventional fibre SPR sensors can be substantially improved by optimizing the incident angle. Furthermore, our investigation suggests some problems in previous reports. (paper)

  4. Theoretical study of the effect of pump wavelength drift on mode instability in a high-power fiber amplifier

    Science.gov (United States)

    Liu, Yakun; Tao, Rumao; Su, Rongtao; Wang, Xiaolin; Ma, Pengfei; Zhang, Hanwei; Zhou, Pu; Si, Lei

    2018-04-01

    This paper presents an investigation of the effect of pump wavelength drift on the threshold of mode instability (MI) in high-power ytterbium-doped fiber lasers. By using a semi-analytical model, we study the effects of pump wavelength drift with a central pump wavelength around 976 nm and 915 nm, respectively. The influences of the pump absorption coefficient and total pump absorption are considered simultaneously. The results indicate that the effect of pump wavelength drift around 976 nm is stronger than that around 915 nm. For more efficient suppression of MI by shifting the pump wavelength, efficient absorption of pump power is required. The MI thresholds for fibers with different total pump absorptions and cladding diameters are compared. When the total pump absorption is increased, the gain saturation is enhanced, which results in the MI being mitigated more effectively and being more sensitive to pump wavelength drift. The MI threshold in gain fibers with larger inner cladding diameter is higher but more dependent upon pump wavelength. The results of this work can help in optimizing the pump wavelength and fiber parameters and suppressing MI in high-power fiber lasers.

  5. Short-Wavelength Countermeasures for Circadian Desynchrony

    National Research Council Canada - National Science Library

    Heller, H. C; Smith, Mark

    2008-01-01

    .... Exposure of humans to bright light for an hour or more at the right phase of the circadian cycle produces significant phase shifts of circadian rhythms speeding recovery from jet-lag, and optimizing...

  6. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Wilson, J.F.; Sherwood, D.G.

    1982-01-01

    A mechanical spectral shift reactor comprises a reactive core having fuel assemblies accommodating both water displacer elements and neutron absorbing control rods for selectively changing the volume of water-moderator in the core. The fuel assemblies with displacer and control rods are arranged in alternating fashion so that one displacer element drive mechanism may move displacer elements in more than one fuel assembly without interfering with the movement of control rods of a corresponding control rod drive mechanisms. (author)

  7. High power multiple wavelength diode laser stack for DPSSL application without temperature control

    Science.gov (United States)

    Hou, Dong; Yin, Xia; Wang, Jingwei; Chen, Shi; Zhan, Yun; Li, Xiaoning; Fan, Yingmin; Liu, Xingsheng

    2018-02-01

    High power diode laser stack is widely used in pumping solid-state laser for years. Normally an integrated temperature control module is required for stabilizing the output power of solid-state laser, as the output power of the solid-state laser highly depends on the emission wavelength and the wavelength shift of diode lasers according to the temperature changes. However the temperature control module is inconvenient for this application, due to its large dimension, high electric power consumption and extra adding a complicated controlling system. Furthermore, it takes dozens of seconds to stabilize the output power when the laser system is turned on. In this work, a compact hard soldered high power conduction cooled diode laser stack with multiple wavelengths is developed for stabilizing the output power of solid-state laser in a certain temperature range. The stack consists of 5 laser bars with the pitch of 0.43mm. The peak output power of each bar in the diode laser stack reaches as much as 557W and the combined lasing wavelength spectrum profile spans 15nm. The solidstate laser, structured with multiple wavelength diode laser stacks, allows the ambient temperature change of 65°C without suddenly degrading the optical performance.

  8. A novel fast phase correlation algorithm for peak wavelength detection of Fiber Bragg Grating sensors.

    Science.gov (United States)

    Lamberti, A; Vanlanduit, S; De Pauw, B; Berghmans, F

    2014-03-24

    Fiber Bragg Gratings (FBGs) can be used as sensors for strain, temperature and pressure measurements. For this purpose, the ability to determine the Bragg peak wavelength with adequate wavelength resolution and accuracy is essential. However, conventional peak detection techniques, such as the maximum detection algorithm, can yield inaccurate and imprecise results, especially when the Signal to Noise Ratio (SNR) and the wavelength resolution are poor. Other techniques, such as the cross-correlation demodulation algorithm are more precise and accurate but require a considerable higher computational effort. To overcome these problems, we developed a novel fast phase correlation (FPC) peak detection algorithm, which computes the wavelength shift in the reflected spectrum of a FBG sensor. This paper analyzes the performance of the FPC algorithm for different values of the SNR and wavelength resolution. Using simulations and experiments, we compared the FPC with the maximum detection and cross-correlation algorithms. The FPC method demonstrated a detection precision and accuracy comparable with those of cross-correlation demodulation and considerably higher than those obtained with the maximum detection technique. Additionally, FPC showed to be about 50 times faster than the cross-correlation. It is therefore a promising tool for future implementation in real-time systems or in embedded hardware intended for FBG sensor interrogation.

  9. Dual-wavelength external cavity laser device for fluorescence suppression in Raman spectroscopy

    Science.gov (United States)

    Zhang, Xuting; Cai, Zhijian; Wu, Jianhong

    2017-10-01

    Raman spectroscopy has been widely used in the detection of drugs, pesticides, explosives, food additives and environmental pollutants, for its characteristics of fast measurement, easy sample preparation, and molecular structure analyzing capability. However, fluorescence disturbance brings a big trouble to these applications, with strong fluorescence background covering up the weak Raman signals. Recently shifted excitation Raman difference spectroscopy (SERDS) not only can completely remove the fluorescence background, but also can be easily integrated into portable Raman spectrometers. Usually, SERDS uses two lasers with small wavelength gap to excite the sample, then acquires two spectra, and subtracts one to the other to get the difference spectrum, where the fluorescence background will be rejected. So, one key aspects of successfully applying SERDS method is to obtain a dual-wavelength laser source. In this paper, a dual-wavelength laser device design based on the principles of external cavity diode laser (ECDL) is proposed, which is low-cost and compact. In addition, it has good mechanical stability because of no moving parts. These features make it an ideal laser source for SERDS technique. The experiment results showed that the device can emit narrow-spectral-width lasers of two wavelengths, with the gap smaller than 2 nanometers. The laser power corresponding to each wavelength can be up to 100mW.

  10. Cavity Attenuated Phase Shift (CAPS) Monitor Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Sedlacek, Arthur J. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-04-01

    The CAPS PMex monitor is a cavity attenuated phase shift extinction instrument. It operates as an optical extinction spectrometer, using a visible-light-emitting diode (LED) as the light source, a sample cell incorporating two high-reflectivity mirrors centered at the wavelength of the LED, and a vacuum photodiode detector. Its efficacy is based on the fact that aerosols are broadband scatterers and absorbers of light.

  11. Long wavelength irregularities in the equatorial electrojet

    International Nuclear Information System (INIS)

    Kudeki, E.; Farley, D.T.; Fejer, B.G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion-acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear theory of the electrojet instability explains this and several other observed features of these dominant primary waves

  12. Design alternatives for wavelength routing networks

    Science.gov (United States)

    Miliotis, K.; Papadimitriou, G. I.; Pomportsis, A. S.

    2003-03-01

    This paper attempts to provide a high level overview of many of the technologies employed in optical networks with a focus on wavelength-routing networks. Optical networks involve a number of technologies from the physics of light through protocols and networks architectures. In fact there is so much technology and know-how that most people involved with optical networks only have a full understanding of the narrow area they deal with. We start first examining the principles that govern light and its use as a wave guide, and then turn our focus to the various components that constitute an optical network and conclude with the description of all optical networks and wavelength-routed networks in greater detail.

  13. Long wavelength irregularities in the equatorial electrojet

    OpenAIRE

    Kudeki, E.; Farley, D. T.; Fejer, Bela G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach...

  14. Optical Detection in Ultrafast Short Wavelength Science

    International Nuclear Information System (INIS)

    Fullagar, Wilfred K.; Hall, Chris J.

    2010-01-01

    A new approach to coherent detection of ionising radiation is briefly motivated and recounted. The approach involves optical scattering of coherent light fields by colour centres in transparent solids. It has significant potential for diffractive imaging applications that require high detection dynamic range from pulsed high brilliance short wavelength sources. It also motivates new incarnations of Bragg's X-ray microscope for pump-probe studies of ultrafast molecular structure-dynamics.

  15. Short wavelength striations on expanding plasma clouds

    International Nuclear Information System (INIS)

    Winske, D.; Gary, S.P.

    1989-01-01

    The growth and evolution of short wavelength (< ion gyroradius) flute modes on a plasma expanding across an ambient magnetic field have been actively studied in recent years, both by means of experiments in the laboratory as well as in space and through numerical simulations. We review the relevant observations and simulations results, discuss the instability mechanism and related linear theory, and describe recent work to bring experiments and theory into better agreement. 30 refs., 6 figs

  16. Optically coupled cavities for wavelength switching

    Energy Technology Data Exchange (ETDEWEB)

    Costazo-Caso, Pablo A; Granieri, Sergio; Siahmakoun, Azad, E-mail: pcostanzo@ing.unlp.edu.ar, E-mail: granieri@rose-hulman.edu, E-mail: siahmako@rose-hulman.edu [Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN 47803 (United States)

    2011-01-01

    An optical bistable device which presents hysteresis behavior is proposed and experimentally demonstrated. The system finds applications in wavelength switching, pulse reshaping and optical bistability. It is based on two optically coupled cavities named master and slave. Each cavity includes a semiconductor optical amplifier (SOA), acting as the gain medium of the laser, and two pair of fiber Bragg gratings (FBG) which define the lasing wavelength (being different in each cavity). Finally, a variable optical coupler (VOC) is employed to couple both cavities. Experimental characterization of the system performance is made analyzing the effects of the coupling coefficient between the two cavities and the driving current in each SOA. The properties of the hysteretic bistable curve and switching can be controlled by adjusting these parameters and the loss in the cavities. By selecting the output wavelength ({lambda}{sub 1} or {lambda}{sub 2}) with an external filter it is possible to choose either the invert or non-invert switched signal. Experiments were developed employing both optical discrete components and a photonic integrated circuit. They show that for 8 m-long cavities the maximum switching frequency is about 500 KHz, and for 4 m-long cavities a minimum rise-time about 21 ns was measured. The switching time can be reduced by shortening the cavity lengths and using photonic integrated circuits.

  17. Wavelength switching in an optical klystron

    International Nuclear Information System (INIS)

    Berryman, K.W.; Smith, T.I.

    1995-01-01

    A symmetric optical klystron consists of two identical undulator sections separated a dispersive section. For a device of a given length, an optical klystron is capable of producing much more bunching, and therefore more gain, than a traditional undulator. Another consequence of introducing dispersion between two undulator sections is that the overall spontaneous radiation pattern results from the interference between the two undulator sections, and as such resembles a standard undulator radiation pattern modulated by a sinusoidal interference term. The presence of several wavelength peaks in the spontaneous lineshape implies an equal number of peaks in the gain spectrum. If the strength of the dispersion section is adjusted to provide nearly equal gain on the two largest of these peaks, then they will compete, and the FEL may switch wavelengths based on noise, cavity length, or other perturbations. We provide the first observations of this behavior, using the FIREFLY system at the Stanford Picosecond FEL Center. In FIREFLY, relative wavelength switching by more than 3%--more than twice the laser linewidth-has been observed by varying dispersion section strength, while at intermediate points stable switching has also been observed as a function of cavity length

  18. Multiple wavelength X-ray monochromators

    International Nuclear Information System (INIS)

    Steinmeyer, P.A.

    1992-01-01

    An improved apparatus and method is provided for separating input x-ray radiation containing first and second x-ray wavelengths into spatially separate first and second output radiation which contain the first and second x-ray wavelengths, respectively. The apparatus includes a crystalline diffractor which includes a first set of parallel crystal planes, where each of the planes is spaced a predetermined first distance from one another. The crystalline diffractor also includes a second set of parallel crystal planes inclined at an angle with respect to the first set of crystal planes where each of the planes of the second set of parallel crystal planes is spaced a predetermined second distance from one another. In one embodiment, the crystalline diffractor is comprised of a single crystal. In a second embodiment, the crystalline diffractor is comprised of a stack of two crystals. In a third embodiment, the crystalline diffractor includes a single crystal that is bent for focusing the separate first and second output x-ray radiation wavelengths into separate focal points. 3 figs

  19. Wavelength conversion from C- to L-band at 10 Gbit/s including transmission over 80 km of SSMF

    DEFF Research Database (Denmark)

    Poulsen, Henrik Nørskov; Buxens Azcoaga, Alvaro Juan; Clausen, Anders

    2000-01-01

    As the need for capacity increases, means to accommodate the growth is getting increasingly important. Hence, higher bit rates and an ever increasing number of WDM channels is being employed. This has led to the introduction of the L-band (ranging from 1570 to 1610 nm) as the new transmission...... window, opening up for-in conjunction with the C-band-an astonishing 80 nm of available bandwidth. However, as the number of wavelength channels increases, the need for wavelength conversion is becoming ever more pronounced. To perform the wavelength conversion, interferometric structures...... such as the monolithically integrated Mach-Zehnder interferometers (SOA-MZI) using semiconductor optical amplifiers as phase-shifting elements have proven excellent candidates. Here we present the conversion and transmission properties of a fully packaged device capable of wavelength conversion from C- to L-band having more...

  20. Reduction of reabsorption effects in scintillators by employing solutes with large Stokes shifts

    International Nuclear Information System (INIS)

    Harrah, L.A.; Renschler, C.L.

    1986-01-01

    A radiation or high energy particle responsive system is described useful as a scintillator, and comprising, a first component which interacts with the radiation or high energy particle to emit photons in a certain first wavelength range; and at least one additional solute component which absorbs the photons in the first wavelength range and thereupon emits photons in another wavelength range higher than the first range; the improvement wherein at least one of the components absorbs substantially no photons in the wavelength range in which it emits photons, due to large Stokes shift caused by an excited states intramolecular rearrangement, with the proviso that the component having a large Stokes shift is not methyl salicylate or salicyclic acid

  1. The shifting beverage landscape.

    Science.gov (United States)

    Storey, Maureen

    2010-04-26

    STOREY, M.L. The shifting beverage landscape. PHYSIOL BEHAV, 2010. - Simultaneous lifestyle changes have occurred in the last few decades, creating an imbalance in energy intake and energy expenditure that has led to overweight and obesity. Trends in the food supply show that total daily calories available per capita increased 28% since 1970. Total energy intake among men and women has also increased dramatically since that time. Some have suggested that intake of beverages has had a disproportional impact on obesity. Data collected by the Beverage Marketing Corporation between 1988-2008 demonstrate that, in reality, fewer calories per ounce are being produced by the beverage industry. Moreover, data from the National Cancer Institute show that soft drink intake represents 5.5% of daily calories. Data from NHANES 1999-2003 vs. 2003-06 may demonstrate a shift in beverage consumption for age/gender groups, ages 6 to>60years. The beverages provided in schools have significantly changed since 2006 when the beverage industry implemented School Beverage Guidelines. This voluntary action has removed full-calorie soft drinks from participating schools across the country. This shift to lower-calorie and smaller-portion beverages in school has led to a significant decrease in total beverage calories in schools. These data support the concept that to prevent and treat obesity, public health efforts should focus on energy balance and that a narrow focus on sweetened beverages is unlikely to have any meaningful impact on this complex problem. Copyright 2010 Elsevier Inc. All rights reserved.

  2. Mechanical spectral shift reactor

    International Nuclear Information System (INIS)

    Doshi, P.K.; George, R.A.; Dollard, W.J.

    1982-01-01

    A mechanical spectral shift arrangement for controlling a nuclear reactor includes a plurality of reactor coolant displacer members which are inserted into a reactor core at the beginning of the core life to reduce the volume of reactor coolant-moderator in the core at start-up. However, as the reactivity of the core declines with fuel depletion, selected displacer members are withdrawn from the core at selected time intervals to increase core moderation at a time when fuel reactivity is declining. (author)

  3. Spectral shift reactor

    International Nuclear Information System (INIS)

    Carlson, W.R.; Piplica, E.J.

    1982-01-01

    A spectral shift pressurized water reactor comprising apparatus for inserting and withdrawing water displacer elements having differing neutron absorbing capabilities for selectively changing the water-moderator volume in the core thereby changing the reactivity of the core. The displacer elements comprise substantially hollow cylindrical low neutron absorbing rods and substantially hollow cylindrical thick walled stainless rods. Since the stainless steel displacer rods have greater neutron absorbing capability, they can effect greater reactivity change per rod. However, by arranging fewer stainless steel displacer rods in a cluster, the reactivity worth of the stainless steel displacer rod cluster can be less than a low neutron absorbing displacer rod cluster. (author)

  4. The role of the second zero-dispersion wavelength in generation of supercontinua and brigth-bright soliton-pairs across the zero-dispersion wavelength

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch; Falk, Peter Andreas; Bang, Ole

    2005-01-01

    Supercontinuum generation with femtosecond pulses in photonic crystal fibers with two zero-dispersion wavelengths (ZDWs) is investigated numerically. The role of the higher ZDW is examined for 5 fiber designs with a nearly constant lower ZDW. It is found that the resulting spectrum is mainly....... Further, the generation of a bright-bright soliton-pair from an initial single red-shifted soliton is found. The soliton-pair has one color in the anomalous dispersion region and the other color in the normal dispersion region, which has not previously been described for bright-bright soliton-pairs....

  5. Repetition and Translation Shifts

    Directory of Open Access Journals (Sweden)

    Simon Zupan

    2006-06-01

    Full Text Available Repetition manifests itself in different ways and at different levels of the text. The first basic type of repetition involves complete recurrences; in which a particular textual feature repeats in its entirety. The second type involves partial recurrences; in which the second repetition of the same textual feature includes certain modifications to the first occurrence. In the article; repetitive patterns in Edgar Allan Poe’s short story “The Fall of the House of Usher” and its Slovene translation; “Konec Usherjeve hiše”; are compared. The author examines different kinds of repetitive patterns. Repetitions are compared at both the micro- and macrostructural levels. As detailed analyses have shown; considerable microstructural translation shifts occur in certain types of repetitive patterns. Since these are not only occasional; sporadic phenomena; but are of a relatively high frequency; they reduce the translated text’s potential for achieving some of the gothic effects. The macrostructural textual property particularly affected by these shifts is the narrator’s experience as described by the narrative; which suffers a reduction in intensity.

  6. Shift Work: Improving Daytime Sleep

    Science.gov (United States)

    ... night. Good daytime sleep is possible, though, if shift work is a necessary part of your work life. ... mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/shift-work/faq-20057991 . Mayo Clinic Footer Legal Conditions and ...

  7. Pixel super resolution using wavelength scanning

    Science.gov (United States)

    2016-04-08

    13 Celebi ME, Schaefer G. Color Medical Image Analysis. Netherlands: Springer. 2013. 14 Yamaguchi I, Matsumura T, Kato J. Phase-shifting color...2016.60 15 Kato J, Yamaguchi I, Matsumura T. Multicolor digital holography with an achromatic phase shifter. Opt Lett 2002; 27: 1403–1405. 16 Ferraro P

  8. Lanthanide shift reagents, binding, shift mechanisms and exchange

    International Nuclear Information System (INIS)

    Boer, J.W.M. de

    1977-01-01

    Paramagnetic lanthanide shift reagents, when added to a solution of a substrate, induce shifts in the nuclear magnetic resonance (NMR) spectrum of the substrate molecules. The induced shifts contain information about the structure of the shift reagent substrate complex. The structural information, however, may be difficult to extract because of the following effects: (1) different complexes between shift reagent and substrate may be present in solution, e.g. 1:1 and 1:2 complexes, and the shift observed is a weighed average of the shifts of the substrate nuclei in the different complexes; (2) the Fermi contact interaction, arising from the spin density at the nucleus, contributes to the induced shift; (3) chemical exchange effects may complicate the NMR spectrum. In this thesis, the results of an investigation into the influence of these effects on the NMR spectra of solutions containing a substrate and LSR are presented. The equations describing the pseudo contact and the Fermi contact shift are derived. In addition, it is shown how the modified Bloch equations describing the effect of the chemical exchange processes occurring in the systems studied can be reduced to the familiar equations for a two-site exchange case. The binding of mono- and bifunctional ethers to the shift reagent are reported. An analysis of the induced shifts is given. Finally, the results of the experiments performed to study the exchange behavior of dimethoxyethane and heptafluorodimethyloctanedionato ligands are presented

  9. Faktor Dan Penjadualan Shift Kerja

    OpenAIRE

    Maurits, Lientje Setyawati; Widodo, Imam Djati

    2008-01-01

    Work shift has negative effect in physical and mental health, work performance and job accident. Disturbance of circadian rhythms is indicated as source of the problems. This article explores some researches related to the impacts of work shift and establishes basic principles of work shift scheduling that considers human need and limitation.

  10. Isotope shifting capacity of rock

    International Nuclear Information System (INIS)

    Blattner, P.; Department of Scientific and Industrial Research, Lower Hutt

    1980-01-01

    Any oxygen isotope shifted rock volume exactly defines a past throughput of water. An expression is derived that relates the throughput of an open system to the isotope shift of reservoir rock and present-day output. The small isotope shift of Ngawha reservoir rock and the small, high delta oxygen-18 output are best accounted for by a magmatic water source

  11. A radiation research apparatus sensitive to wavelength

    International Nuclear Information System (INIS)

    1980-01-01

    The apparatus described is equipped with a radiation source with a tuning device for the generation of X radiation of at least two different wavelength spectra. The detector with ionisation chamber is able to discriminate between these spectra. This is done with the aid of an auxillary electrode between the entrance window and a high voltage electrode. With a lower source of voltage this electrode has a potential equal to the high voltage electrode potential and with a higher voltage source it has a potential equal to the signal electrode potential. (Th.P.)

  12. Wavelength-agnostic WDM-PON System

    DEFF Research Database (Denmark)

    Wagner, Christoph; Eiselt, Michael; Zou, S.

    2016-01-01

    on the standardization status of this lowcost system in the new ITU-T G.metro draft recommendation, in the context of autonomous tuning. We also discuss some low-effort implementations of the pilot-tone labels and investigate the impact of these labels on the transmission channels.......Next-generation WDM-PON solutions for metro and access systems will take advantage of remotely controlled wavelength-tunable ONUs to keep system costs as low as possible. For such a purpose, each ONU signal can be labeled by a pilot tone modulated onto the optical data stream. We report...

  13. Sub-wavelength imaging at radio frequency

    International Nuclear Information System (INIS)

    Wiltshire, M C K; Pendry, J B; Hajnal, J V

    2006-01-01

    A slab of material with a negative permeability can act as a super-lens for magnetic fields and generate images with a sub-wavelength resolution. We have constructed an effective medium using a metamaterial with negative permeability in the region of 24 MHz, and used this to form images in free space of radio frequency magnetic sources. Measurements of these images show that a resolution of approximately λ/64 has been achieved, consistent with both analytical and numerical predictions. (letter to the editor)

  14. Gold Photoluminescence: Wavelength and Polarization Engineering

    DEFF Research Database (Denmark)

    Andersen, Sebastian Kim Hjælm; Pors, Anders Lambertus; Bozhevolnyi, Sergey I.

    2015-01-01

    We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes...... and dimensions of gold nanoparticles influences the GSPR wavelength and polarization characteristics, thereby allowing us to enhance and spectrally mold the plasmon-assisted PL while simultaneously controlling its polarization. In order to understand the underlying physics behind the plasmon-enhanced PL, we...

  15. Wavelength converter placement in optical networks with dynamic traffic

    DEFF Research Database (Denmark)

    Buron, Jakob Due; Ruepp, Sarah Renée; Wessing, Henrik

    2008-01-01

    We evaluate the connection provisioning performance of GMPLS-controlled wavelength routed networks under dynamic traffic load and using three different wavelength converter placement heuristics. Results show that a simple uniform placement heuristic matches the performance of complex heuristics...

  16. The shift in windpower

    International Nuclear Information System (INIS)

    Gipe, P.

    1992-01-01

    Despite new production records, the near-term market for new windpower projects in the US remains bleak. Congressional incentives and project proposals in the mid-1990s offer promise, but for now most development has shifted to Europe. During 1992 and 1993 the largest wind projects developed by US companies will not be in the US, but in the United Kingdom and Spain. Indeed, most of the US's windpower industry is going abroad, establishing offices overseas. This move toward Europe comes as little surprise. New project development for US firms has faltered at home while the European market has burgeoned. The topics of the article include the move to Europe, a reduction in California's share of producing wind power plants, a rise in Europe's share of producing wind power plants, the future market for wind power in the US, and reawakening California's market

  17. Short-wavelength electrostatic waves in the earth's magnetosheath

    International Nuclear Information System (INIS)

    Gallagher, D.L.

    1985-01-01

    Recent observations with the ISEE 1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emission has a characteristic parabola shape or ''festoon'' shape. The low-frequency cutoff ranges from 100 to 400 Hz, while the high-frequency limit ranges from about 1 to 4 kHz. The bandwidth is found to minimize for antenna orientations parallel to the wave vectors. The wave vector does not appear to be related to the local magnetic field, the plasma flow velocity, or the spacecraft-sun directions. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler-shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest frame wave vectors and frequencies indicate that emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 40 and 600 m. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath

  18. Short wavelength electrostatic waves in the earth's magnetosheath

    International Nuclear Information System (INIS)

    Gallagher, D.L.

    1982-01-01

    Recent observations with the ISEE-1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emissions has a characteristic parabola shape or ''festoon'' shape. The low frequency cutoff ranges from 100 Hz to 400 Hz, while the high frequency limit ranges from about 1kHz to 4kHz. The bandwidth is found to minimize for antenna orientations parallel to these wave number vectors, requiring the confinement of those vectors to a plane which contains the geocentric solar eclilptic coordinate z-axis. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest-frame wave vectors and frequencies indicate that the emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 30 meters and 600 meters. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k vector direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath

  19. Passively synchronized dual-wavelength Q-switched lasers

    DEFF Research Database (Denmark)

    Janousek, Jiri; Tidemand-Lichtenberg, Peter; Mortensen, Jesper Liltorp

    We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG.......We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG....

  20. Simple approach to three-color two-photon microscopy by a fiber-optic wavelength convertor.

    Science.gov (United States)

    Li, Kuen-Che; Huang, Lynn L H; Liang, Jhih-Hao; Chan, Ming-Che

    2016-11-01

    A simple approach to multi-color two-photon microscopy of the red, green, and blue fluorescent indicators was reported based on an ultra-compact 1.03-μm femtosecond laser and a nonlinear fiber. Inside the nonlinear fiber, the 1.03-μm laser pulses were simultaneously blue-shifted to 0.6~0.8 μm and red-shifted to 1.2~1.4 μm region by the Cherenkov radiation and fiber Raman gain effects. The wavelength-shifted 0.6~0.8 μm and 1.2~1.4 μm radiations were co-propagated with the residual non-converted 1.03-μm pulses inside the same nonlinear fiber to form a fiber-output three-color femtosecond source. The application of the multi-wavelength sources on multi-color two-photon fluorescence microscopy were also demonstrated. Overall, due to simple system configuration, convenient wavelength conversion, easy wavelength tunability within the entire 0.7~1.35 μm bio-penetration window and less requirement for high power and bulky light sources, the simple approach to multi-color two-photon microscopy could be widely applicable as an easily implemented and excellent research tool for future biomedical and possibly even clinical applications.

  1. Meter-wavelength VLBI. III. Pulsars

    International Nuclear Information System (INIS)

    Vandenberg, N.R.; Clark, T.A.; Clark, W.C.; Erickson, W.C.; Resch, G.M.; Broderick, J.J.

    1976-01-01

    The results and analysis of observations of pulsars, especially the Crab Nebula pulsar, taken during a series of meter-wavelength very long baseline interferometry (VLBI) experiments are discussed. Based on a crude 144 MHz visibility curve which is consistent with a Gaussian brightness distribution, the measured visibilities at 196, 111, and 74 MHz were interpreted to yield apparent angular diameters (at half-power) of 0 .03 +- 0 .01, 0 .07 +- 0 .01, and 0 .18 +- 0 .01, respectively. These sizes scale approximately as wavelength-squared, and the 74 MHz size agrees with recent observations using interplanetary scintillation techniques.The VLBI-measured total flux densities lie on the extrapolation from higher frequencies of the pulsing flux densities. Variations in the total flux density up to 25 percent were observed. A lack of fine structure other than the pulsar in the nebula is indicated by our simple visibility curves. The pulse shapes observed with the interferometer are similar to single-dish measurements at 196 MHz but reveal a steady, nonpulsing component at 111 MHz. The ratio of pulsing to total power was approximately equal to one-half but varied with time. No pulsing power was detected at 74 MHz. It was found that four strong, low-dispersion pulsars were only slightly resolved

  2. Long-wavelength microinstabilities in toroidal plasmas

    International Nuclear Information System (INIS)

    Tang, W.W.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in TFTR L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

  3. Dye mixtures for ultrafast wavelength shifters

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, S.; Liu, L.; Palsule, C.; Borst, W.; Wigmans, R. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Physics; Barashkov, N. [Karpov Inst. of Physical Chemistry, Moscow (Russian Federation)

    1994-12-31

    Particle detectors based on scintillation processes have been used since the discovery of radium about 100 years ago. The fast signals that can be obtained with these detectors, although often considered a nice asset, were rarely essential for the success of experiments. However, the new generation of high energy particle accelerators require particle detectors with fast response time. The authors have produced fast wavelength shifters using mixtures of various Coumarin dyes with DCM in epoxy-polymers (DGEBA+HHPA) and measured the properties of these wavelength shifters. The particular mixtures were chosen because there is a substantial overlap between the emission spectrum of Coumarin and the absorption spectrum of DCM. The continuous wave and time-resolved fluorescence spectra have been studied as a function of component concentration to optimize the decay times, emission peaks and quantum yields. The mean decay times of these mixtures are in the range of 2.5--4.5 ns. The mean decay time increases with an increase in Coumarin concentration at a fixed DCM concentration or with a decrease in DCM concentration at a fixed Coumarin concentration. This indicates that the energy transfer is radiative at lower relative DCM concentrations and becomes non-radiative at higher DCM concentrations.

  4. Dye mixtures for ultrafast wavelength shifters

    International Nuclear Information System (INIS)

    Gangopadhyay, S.; Liu, L.; Palsule, C.; Borst, W.; Wigmans, R.

    1994-01-01

    Particle detectors based on scintillation processes have been used since the discovery of radium about 100 years ago. The fast signals that can be obtained with these detectors, although often considered a nice asset, were rarely essential for the success of experiments. However, the new generation of high energy particle accelerators require particle detectors with fast response time. The authors have produced fast wavelength shifters using mixtures of various Coumarin dyes with DCM in epoxy-polymers (DGEBA+HHPA) and measured the properties of these wavelength shifters. The particular mixtures were chosen because there is a substantial overlap between the emission spectrum of Coumarin and the absorption spectrum of DCM. The continuous wave and time-resolved fluorescence spectra have been studied as a function of component concentration to optimize the decay times, emission peaks and quantum yields. The mean decay times of these mixtures are in the range of 2.5--4.5 ns. The mean decay time increases with an increase in Coumarin concentration at a fixed DCM concentration or with a decrease in DCM concentration at a fixed Coumarin concentration. This indicates that the energy transfer is radiative at lower relative DCM concentrations and becomes non-radiative at higher DCM concentrations

  5. Coherence techniques at extreme ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chang [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. third generation synchrotron radiation facilities), and novel optical components, that in turn permit new research in areas that have not yet been fully explored. This dissertation is directed towards advancing this new field by contributing to the characterization of spatial coherence properties of undulator radiation and, for the first time, introducing Fourier optical elements to this short-wavelength spectral region. The first experiment in this dissertation uses the Thompson-Wolf two-pinhole method to characterize the spatial coherence properties of the undulator radiation at Beamline 12 of the Advanced Light Source. High spatial coherence EUV radiation is demonstrated with appropriate spatial filtering. The effects of small vertical source size and beamline apertures are observed. The difference in the measured horizontal and vertical coherence profile evokes further theoretical studies on coherence propagation of an EUV undulator beamline. A numerical simulation based on the Huygens-Fresnel principle is performed.

  6. WDM cross-connect cascade based on all-optical wavelength converters for routing and wavelength slot interchanging using a reduced number of internal wavelengths

    DEFF Research Database (Denmark)

    Pedersen, Rune Johan Skullerud; Mikkelsen, Benny; Jørgensen, Bo Foged

    1998-01-01

    interchanging can be used to create a robust and nonblocking OXC. However, for an OXC with n fiber inlets each carrying m wavelengths the OXC requires n×m internal wavelengths, which constrains the size of the cross-connect. In this paper we therefore propose and demonstrate an architecture that uses a reduced......Optical transport layers need rearrangeable wavelength-division multiplexing optical cross-connects (OXCs) to increase the capacity and flexibility of the network. It has previously been shown that a cross-connect based on all-optical wavelength converters for routing as well as wavelength slot...... set of internal wavelengths without sacrificing cross-connecting capabilities. By inserting a partly equipped OXC with the new architecture in a 10-Gbit/s re-circulating loop setup we demonstrate the possibility of cascading up to ten OXCs. Furthermore, we investigate the regenerating effect...

  7. Application of holographic sub-wavelength diffraction gratings for monitoring of kinetics of bioprocesses

    International Nuclear Information System (INIS)

    Tamulevičius, Tomas; Šeperys, Rimas; Andrulevičius, Mindaugas; Kopustinskas, Vitoldas; Meškinis, Šarūnas; Tamulevičius, Sigitas; Mikalayeva, Valeryia; Daugelavičius, Rimantas

    2012-01-01

    Highlights: ► Refractive index sensor based on DLC holographic sub-wavelength period grating. ► Spectroscopic analysis of polarized white light reflected from the grating. ► Control of critical wavelength shift and reflectivity changes. ► Testing of model liquid analyte materials. ► Evaluation of interaction between B. subtilis cells and lysozyme. - Abstract: In this work we present a refractive index (RI) sensor based on a sub-wavelength holographic diffraction grating. The sensor chip was fabricated by dry etching of the finely spaced (d = 428 nm) diffraction grating in SiO x doped diamond like carbon (DLC) film. It is shown that employing a fabricated sensor chip, and using the proposed method of analysis of data, one can inspect kinetics of processes in liquids occurring in the vicinity of the grating surface. The method is based on the spectral composition analysis of polarized polychromatic light reflected from the sub-wavelength diffraction grating. The RI measurement system was tested with different model liquid analytes including 25 wt.%, 50 wt.% sugar water solutions, 10 °C, 50 °C distilled water, also Gram-positive bacteria Bacillus subtilis interaction with ion-permeable channels forming antibiotic gramicidin D and a murolytic enzyme lysozyme. Analysis of the data set of specular reflection spectra enabled us to follow the kinetics of the RI changes in the analyte with millisecond resolution. Detectable changes in the effective RI were not worse than Δn = 10 −4 .

  8. Tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal structure

    International Nuclear Information System (INIS)

    Huang, Wenbin; Pu, Donglin; Qiao, Wen; Wan, Wenqiang; Liu, Yanhua; Ye, Yan; Wu, Shaolong; Chen, Linsen

    2016-01-01

    A continuously tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal cavity is demonstrated. The triangular-lattice resonator was initially fabricated through multiple interference exposure and was then replicated into a low refractive index polymer via UV-nanoimprinting. The blend of a blue-emitting conjugated polymer and a red-emitting one was used as the gain medium. Three periods in the scalene triangular-lattice structure yield stable tri-wavelength laser emission (625.5 nm, 617.4 nm and 614.3 nm) in six different directions. A uniformly aligned liquid crystal (LC) layer was incorporated into the cavity as the top cladding layer. Upon heating, the orientation of LC molecules and thus the effective refractive index of the lasing mode changes which continuously shifts the lasing wavelength. A maximum tuning range of 12.2 nm was observed for the lasing mode at 625.5 nm. This tunable tri-wavelength polymer laser is simple constructed and cost-effective. It may find application in the fields of biosensors and photonic integrated circuits. (paper)

  9. Integrated Wavelength-Tunable Light Source for Optical Gas Sensing Systems

    Directory of Open Access Journals (Sweden)

    Bin Li

    2015-01-01

    Full Text Available A compact instrument consisting of a distributed feedback laser (DFB at 1.65 μm was developed as a light source for gas sensing systems using tunable diode laser absorption spectroscopy (TDLAS technique. The wavelength of laser is tuned by adjusting the laser working temperature and injection current, which are performed by self-developed temperature controller and current modulator respectively. Stability test shows the fluctuation of the laser temperature is within the range of ±0.02°C. For gas detection experiments, the wavelength is tuned around the gas absorption line by adjusting laser temperature and is then shifted periodically to scan across the absorption line by the laser current modulator, which generates a 10 Hz saw wave signal. In addition, the current modulator is able to generate sine wave signal for gas sensing systems using wavelength modulation spectroscopy (WMS technique involving extraction of harmonic signals. The spectrum test proves good stability that the spectrum was measured 6 times every 10 minutes at the constant temperature and current condition. This standalone instrument can be applied as a light source for detection systems of different gases by integrating lasers at corresponding wavelength.

  10. In-line digital holography with phase-shifting Greek-ladder sieves

    Science.gov (United States)

    Xie, Jing; Zhang, Junyong; Zhang, Yanli; Zhou, Shenlei; Zhu, Jianqiang

    2018-04-01

    Phase shifting is the key technique in in-line digital holography, but traditional phase shifters have their own limitations in short wavelength regions. Here, phase-shifting Greek-ladder sieves with amplitude-only modulation are introduced into in-line digital holography, which are essentially a kind of diffraction lens with three-dimensional array diffraction-limited foci. In the in-line digital holographic experiment, we design two kinds of sieves by lithography and verify the validity of their phase-shifting function by measuring a 1951 U.S. Air Force resolution test target and three-dimensional array foci. With advantages of high resolving power, low cost, and no limitations at shorter wavelengths, phase-shifting Greek-ladder sieves have great potential in X-ray holography or biochemical microscopy for the next generation of synchrotron light sources.

  11. Optofluidic intracavity spectroscopy for spatially, temperature, and wavelength dependent refractometry

    Science.gov (United States)

    Kindt, Joel D.

    A microfluidic refractometer was designed based on previous optofluidic intracavity spectroscopy (OFIS) chips utilized to distinguish healthy and cancerous cells. The optofluidic cavity is realized by adding high reflectivity dielectric mirrors to the top and bottom of a microfluidic channel. This creates a plane-plane Fabry-Perot optical cavity in which the resonant wavelengths are highly dependent on the optical path length inside the cavity. Refractometry is a useful method to determine the nature of fluids, including the concentration of a solute in a solvent as well as the temperature of the fluid. Advantages of microfluidic systems are the easy integration with lab-on-chip devices and the need for only small volumes of fluid. The unique abilities of the microfluidic refractometer in this thesis include its spatial, temperature, and wavelength dependence. Spatial dependence of the transmission spectrum is inherent through a spatial filtering process implemented with an optical fiber and microscope objective. A sequence of experimental observations guided the change from using the OFIS chip as a cell discrimination device to a complimentary refractometer. First, it was noted the electrode structure within the microfluidic channel, designed to trap and manipulate biological cells with dielectrophoretic (DEP) forces, caused the resonant wavelengths to blue-shift when the electrodes were energized. This phenomenon is consistent with the negative dn/dT property of water and water-based solutions. Next, it was necessary to develop a method to separate the optical path length into physical path length and refractive index. Air holes were placed near the microfluidic channel to exclusively measure the cavity length with the known refractive index of air. The cavity length was then interpolated across the microfluidic channel, allowing any mechanical changes to be taken into account. After the separation of physical path length and refractive index, it was of interest

  12. Dynamic Sensor Interrogation Using Wavelength-Swept Laser with a Polygon-Scanner-Based Wavelength Filter

    Science.gov (United States)

    Kwon, Yong Seok; Ko, Myeong Ock; Jung, Mi Sun; Park, Ik Gon; Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Park, Kyung Hyun; Jeon, Min Yong

    2013-01-01

    We report a high-speed (∼2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using a wavelength-swept laser (WSL) with a polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and the 10 dB scanning bandwidth is more than 90 nm around a center wavelength of 1,540 nm. The output from the WSL is coupled into the multiplexed FBG array, which consists of five FBGs. The reflected Bragg wavelengths of the FBGs are 1,532.02 nm, 1,537.84 nm, 1,543.48 nm, 1,547.98 nm, and 1,553.06 nm, respectively. A dynamic periodic strain ranging from 500 Hz to 2 kHz is applied to one of the multiplexed FBGs, which is fixed on the stage of the piezoelectric transducer stack. Good dynamic performance of the FBGs and recording of their fast Fourier transform spectra have been successfully achieved with a measuring speed of 18 kHz. The signal-to-noise ratio and the bandwidth over the whole frequency span are determined to be more than 30 dB and around 10 Hz, respectively. We successfully obtained a real-time measurement of the abrupt change of the periodic strain. The dynamic FBG sensor interrogation system can be read out with a WSL for high-speed and high-sensitivity real-time measurement. PMID:23899934

  13. Photoluminescence wavelength variation of monolayer MoS2 by oxygen plasma treatment

    International Nuclear Information System (INIS)

    Kim, Min Su; Nam, Giwoong; Park, Seki; Kim, Hyun; Han, Gang Hee; Lee, Jubok; Dhakal, Krishna P.; Leem, Jae-Young; Lee, Young Hee; Kim, Jeongyong

    2015-01-01

    We performed nanoscale confocal photoluminescence (PL), Raman, and absorption spectral imaging measurements to investigate the optical and structural properties of molybdenum disulfide (MoS 2 ) monolayers synthesized by chemical vapor deposition method and subjected to oxygen plasma treatment for 10 to 120 s under high vacuum (1.3 × 10 −3 Pa). Oxygen plasma treatment induced red shifts of ~ 20 nm in the PL emission peaks corresponding to A and B excitons. Similarly, the peak positions corresponding to A and B excitons of the absorption spectra were red-shifted following oxygen plasma treatment. Based on the confocal PL, absorption, and Raman microscopy results, we suggest that the red-shifting of the A and B exciton peaks originated from shallow defect states generated by oxygen plasma treatment. - Highlights: • Effects of oxygen plasma on optical properties of monolayer MoS 2 were investigated. • Confocal photoluminescence, Raman, and absorption spectral maps are presented. • Wavelength tuning up to ~ 20 nm for the peak emission wavelength was achieved

  14. Photoluminescence wavelength variation of monolayer MoS{sub 2} by oxygen plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Su [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Nam, Giwoong [Department of Nanoscience & Engineering, Inje University, Gimhae 621-749 (Korea, Republic of); Park, Seki; Kim, Hyun [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Han, Gang Hee [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Jubok; Dhakal, Krishna P. [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Leem, Jae-Young [Department of Nanoscience & Engineering, Inje University, Gimhae 621-749 (Korea, Republic of); Lee, Young Hee [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Jeongyong, E-mail: j.kim@skku.edu [Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Energy Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-09-01

    We performed nanoscale confocal photoluminescence (PL), Raman, and absorption spectral imaging measurements to investigate the optical and structural properties of molybdenum disulfide (MoS{sub 2}) monolayers synthesized by chemical vapor deposition method and subjected to oxygen plasma treatment for 10 to 120 s under high vacuum (1.3 × 10{sup −3} Pa). Oxygen plasma treatment induced red shifts of ~ 20 nm in the PL emission peaks corresponding to A and B excitons. Similarly, the peak positions corresponding to A and B excitons of the absorption spectra were red-shifted following oxygen plasma treatment. Based on the confocal PL, absorption, and Raman microscopy results, we suggest that the red-shifting of the A and B exciton peaks originated from shallow defect states generated by oxygen plasma treatment. - Highlights: • Effects of oxygen plasma on optical properties of monolayer MoS{sub 2} were investigated. • Confocal photoluminescence, Raman, and absorption spectral maps are presented. • Wavelength tuning up to ~ 20 nm for the peak emission wavelength was achieved.

  15. Analysis of subsystems in wavelength-division-multiplexing networks

    DEFF Research Database (Denmark)

    Liu, Fenghai

    2001-01-01

    Wavelength division multiplexing (WDM) technology together with optical amplification has created a new era for optical communication. Transmission capacity is greatly increased by adding more and more wavelength channels into a single fiber, as well as by increasing the line rate of each channel...... in semiconductor optical amplifiers (SOAs), and dispersion managed fiber sections. New subsystems are also proposed in the thesis: a modular 2×2 multiwavelength cross-connect using wavelength switching blocks, a wavelength converter based on cross phase modulation in a semiconductor modulator, a wavelength...

  16. Chemical shift imaging: a review

    International Nuclear Information System (INIS)

    Brateman, L.

    1986-01-01

    Chemical shift is the phenomenon that is seen when an isotope possessing a nuclear magnetic dipole moment resonates at a spectrum of resonance frequencies in a given magnetic field. These resonance frequencies, or chemical shifts, depend on the chemical environments of particular nuclei. Mapping the spatial distribution of nuclei associated with a particular chemical shift (e.g., hydrogen nuclei associated with water molecules or with lipid groups) is called chemical shift imaging. Several techniques of proton chemical shift imaging that have been applied in vivo are presented, and their clinical findings are reported and summarized. Acquiring high-resolution spectra for large numbers of volume elements in two or three dimensions may be prohibitive because of time constraints, but other methods of imaging lipid of water distributions (i.e., selective excitation, selective saturation, or variations in conventional magnetic resonance imaging pulse sequences) can provide chemical shift information. These techniques require less time, but they lack spectral information. Since fat deposition seen by chemical shift imaging may not be demonstrated by conventional magnetic resonance imaging, certain applications of chemical shift imaging, such as in the determination of fatty liver disease, have greater diagnostic utility than conventional magnetic resonance imaging. Furthermore, edge artifacts caused by chemical shift effects can be eliminated by certain selective methods of data acquisition employed in chemical shift imaging

  17. Fast charged-coupled device spectrometry using zoom-wavelength optics

    International Nuclear Information System (INIS)

    Carolan, P.G.; Conway, N.J.; Bunting, C.A.; Leahy, P.; OConnell, R.; Huxford, R.; Negus, C.R.; Wilcock, P.D.

    1997-01-01

    Fast charge-coupled device (CCD) detector arrays placed at the output of visible spectrometers are used for multichord Doppler shift analyses on the COMPASS-D and START tokamaks. Unequal magnification in the horizontal and vertical axes allows for optimal matching of throughput and spectral resolution at the CCD detector. This involves cylindrical lenses in an anamorphic mounting. Optical acuity is preserved over a very wide range of wavelengths (220 nm→700 nm) by separate repositioning of all the optical elements which is accomplished by the use of zoom mechanisms. This facilitates rapid changes of wavelength allowing edge and core observations depending on the location of the emitting impurity ions. Changes to the ion temperature and velocity are recorded using 20 chords simultaneously with typical accuracies of Δv i -1 and ΔT i /T i <10% with a time resolution of <1 ms. copyright 1997 American Institute of Physics

  18. Multiple soliton self-frequency shift cancellations in a temporally tailored photonic crystal fiber

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lai; Kang, Zhe; Li, Qing; Gao, Xuejian; Qin, Guanshi, E-mail: qings@jlu.edu.cn, E-mail: wpqin@jlu.edu.cn; Qin, Weiping, E-mail: qings@jlu.edu.cn, E-mail: wpqin@jlu.edu.cn [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Liao, Meisong; Hu, Lili [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Ohishi, Yasutake [Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2014-11-03

    We report the generation of multiple soliton self-frequency shift cancellations in a temporally tailored tellurite photonic crystal fiber (PCF). The temporally regulated group velocity dispersion (GVD) is generated in the fiber by soliton induced optical Kerr effect. Two red-shifted dispersive waves spring up when two Raman solitons meet their own second zero-dispersion-wavelengths in the PCF. These results show how, through temporally tailored GVD, nonlinearities can be harnessed to generate unexpected effects.

  19. Underdense radiation sources: Moving towards longer wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Back, C.A.; Kilkenny, J.D. [General Atomics, San Diego, California (United States); Seely, J.F.; Weaver, J.L. [Naval Research Laboratory, Washington, DC (United States); Feldman, U. [Artep Inc., Ellicott City, MD (United States); Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A. [Lawrence Livermore National Laboratory, California (United States); Tillack, M. [U. C. San Diego, La Jolla, CA (United States)

    2006-06-15

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO{sub 2} aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  20. Underdense radiation sources: Moving towards longer wavelengths

    International Nuclear Information System (INIS)

    Back, C.A.; Kilkenny, J.D.; Seely, J.F.; Weaver, J.L.; Feldman, U.; Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A.; Tillack, M.

    2006-01-01

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO 2 aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  1. Spin and wavelength multiplexed nonlinear metasurface holography

    Science.gov (United States)

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-06-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

  2. Aligning of single and multiple wavelength chromatographic

    DEFF Research Database (Denmark)

    Nielsen, Niels-Peter Vest; Carstensen, Jens Michael; Smedsgaard, Jørn

    1998-01-01

    optimised warping (COW) using two input parameters which can be estimated from the observed peak width. COW is demonstrated on constructed single trace chromatograms and on single and multiple wavelength chromatograms obtained from HPLC diode detection analyses of fungal extractsA copy of the C program......The use of chemometric data processing is becoming an important part of modern chromatography. Most chemometric analyses are performed on reduced data sets using areas of selected peaks detected in the chromatograms, which means a loss of data and introduces the problem of extracting peak data from...... to utilise the entire data matrix or rely on peak detection, thus having the same limitations as the commonly used chemometric procedures. The method presented uses the entire chromatographic data matrices and does not require any preprocessing e.g., peak detection. It relies on piecewise linear correlation...

  3. Single wavelength standard wiggler for PEP

    International Nuclear Information System (INIS)

    Brunk, W.; Fischer, G.; Spencer, J.

    1979-03-01

    A 1lambda planar wiggler has been designed that will be used for the initial operation of the 4 to 18 GeV storage ring PEP. Three of these wigglers will be installed symmetrically around the ring at 120 0 intervals in three of six available 5 m straight sections with the purpose of providing: (1) beam size control to obtain better luminosities below 15 GeV, and (2) decreased damping times to obtain better injection rates at lower energies. Design goals are discussed and a description of the final system including cost estimates is given. Expected results and usage in PEP are discussed. Some possibilities for production of synchrotron radiation and beam monitoring with shorter wavelength, multiple-period wigglers at PEP energies are also discussed. Comparison to a wiggler now operating in SPEAR is given

  4. Long-wavelength microinstabilities in toroidal plasmas

    International Nuclear Information System (INIS)

    Tang, W.M.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Fusion Res. (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 29] L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

  5. Passive directional discrimination in laser-Doppler anemometry by the two-wavelength quadrature homodyne technique.

    Science.gov (United States)

    Büttner, Lars; Czarske, Jürgen

    2003-07-01

    We report a method for passive optical directional discrimination in laser-Doppler anemometers. For this purpose frequency-shift elements such as acousto-optic modulators, which are bulky and difficult to align during assembly, have traditionally been employed. We propose to use a quadrature homodyne technique to achieve directional discrimination of the fluid flow without any frequency-shift elements. It is based on the employment of two laser wavelengths, which generate two interference fringe systems with a phase shift of a quarter of the common fringe spacing. Measurement signal pairs with a direction-dependent phase shift of +/- pi/2 are generated. As a robust signal-processing technique, the cross-correlation technique is used. The principles of quadrature homodyne laser-Doppler anemometry are investigated. A setup that provides a constant phase shift of pi/2 throughout the entire measurement volume was achieved with both single-mode and multimode radiation. The directional discrimination was successfully verified with wind tunnel measurements. The complete passive technique offers the potential of building miniaturized measurement heads that can be integrated, e.g., into wind tunnel models.

  6. Wavelength stabilized high pulse power laser diodes for automotive LiDAR

    Science.gov (United States)

    Knigge, A.; Klehr, A.; Wenzel, H.; Zeghuzi, A.; Fricke, J.; Maaßdorf, A.; Liero, A.; Tränkle, G.

    2018-03-01

    Diode lasers generating optical pulses with high peak power and lengths in the nanosecond range are key components of systems for free-space communication, metrology, material processing, spectroscopy, and light detection and ranging (LiDAR) as needed for object detection and autonomous driving. Automotive LiDAR systems demand additionally a good beam quality and low wavelength shift with temperature due to the wide operating temperature span. We present here internally wavelength stabilized lasers emitting ns optical pulses from an emission aperture between 30 μm and 100 μm with peak powers of tens of Watts at wavelengths around 905 nm. The vertical structure based on AlGaAs (confinement and cladding layers) and InGaAs (active quantum well) is especially optimized for pulsed operation with respect to the implementation of a surface Bragg grating with a high reflectivity. The fabricated 6 mm long distributed Bragg reflector (DBR) broad area (BA) lasers are electrically driven by an in-house developed high-speed unit generating 3 to 10 ns long nearly rectangular shaped current pulses with amplitudes of up to 250 A. Such lasers emit optical pulses with a peak power of more than 30 W at 95 A pulse current up to a temperature of 85°C with a wavelength shift as low as 65 pm/K and a lateral beam propagation factor less than 10. The influence of the lateral aperture width and the pulse length on the beam quality will be shown. A monolithic integration of 3 DBR BA lasers on a single chip whose emission can be combined into a single beam raises the output power to more than 100 W.

  7. Chemical shift homology in proteins

    International Nuclear Information System (INIS)

    Potts, Barbara C.M.; Chazin, Walter J.

    1998-01-01

    The degree of chemical shift similarity for homologous proteins has been determined from a chemical shift database of over 50 proteins representing a variety of families and folds, and spanning a wide range of sequence homologies. After sequence alignment, the similarity of the secondary chemical shifts of C α protons was examined as a function of amino acid sequence identity for 37 pairs of structurally homologous proteins. A correlation between sequence identity and secondary chemical shift rmsd was observed. Important insights are provided by examining the sequence identity of homologous proteins versus percentage of secondary chemical shifts that fall within 0.1 and 0.3 ppm thresholds. These results begin to establish practical guidelines for the extent of chemical shift similarity to expect among structurally homologous proteins

  8. Shifted-modified Chebyshev filters

    OpenAIRE

    ŞENGÜL, Metin

    2013-01-01

    This paper introduces a new type of filter approximation method that utilizes shifted-modified Chebyshev filters. Construction of the new filters involves the use of shifted-modified Chebyshev polynomials that are formed using the roots of conventional Chebyshev polynomials. The study also includes 2 tables containing the shifted-modified Chebyshev polynomials and the normalized element values for the low-pass prototype filters up to degree 6. The transducer power gain, group dela...

  9. Portable shift register

    International Nuclear Information System (INIS)

    Halbig, J.K.; Bourret, S.C.; Hansen, W.J.; Hicks, D.V.; Klosterbuer, S.F.; Krick, M.S.

    1994-01-01

    An electronics package for a small, battery-operated, self-contained, neutron coincidence counter based on a portable shift-register (PSR) has been developed. The counter was developed for applications not adequately addressed by commercial packages, including in-plant measurements to demonstrate compliance with regulations (domestic and international), in-plant process control, and in-field measurements (environmental monitoring or safeguards). Our package's features, which address these applications, include the following: Small size for portability and ease of installation;battery or mains operation; a built-in battery to power the unit and a typical detector such as a small sample counter, for over 6 h if power lines are bad or noisy, if there is a temporary absence of power, or if portability is desired; complete support, including bias, for standard neutron detectors; a powerful communications package to easily facilitate robust external control over a serial port; and a C-library to simplify creating external control programs in computers or other controllers. Whereas the PSR specifically addresses the applications mentioned above, it also performs all the measurements made by previous electronics packages for neutron coincidence counters developed at Los Alamos and commercialized. The PSR electronics package, exclusive of carrying handle, is 8 by 10 by 20 cm; it contains the circuit boards, battery, and bias supply and weighs less than 2 kg. This instrument package is the second in an emerging family of portable measurement instruments being developed; the first was the Miniature and Modular Multichannel Analyzer (M 3 CA). The PSR makes extensive use of hardware and software developed for the M 3 CA; like the M 3 CA, it is intended primarily for use with an external controller interfaced over a serial channel

  10. Quantized beam shifts in graphene

    Energy Technology Data Exchange (ETDEWEB)

    de Melo Kort-Kamp, Wilton Junior [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sinitsyn, Nikolai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalvit, Diego Alejandro Roberto [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-08

    We predict the existence of quantized Imbert-Fedorov, Goos-Hanchen, and photonic spin Hall shifts for light beams impinging on a graphene-on-substrate system in an external magnetic field. In the quantum Hall regime the Imbert-Fedorov and photonic spin Hall shifts are quantized in integer multiples of the fine structure constant α, while the Goos-Hanchen ones in multiples of α2. We investigate the influence on these shifts of magnetic field, temperature, and material dispersion and dissipation. An experimental demonstration of quantized beam shifts could be achieved at terahertz frequencies for moderate values of the magnetic field.

  11. Wavelength-stepped, actively mode-locked fiber laser based on wavelength-division-multiplexed optical delay lines

    Science.gov (United States)

    Lee, Eunjoo; Kim, Byoung Yoon

    2017-12-01

    We propose a new scheme for an actively mode-locked wavelength-swept fiber laser that produces a train of discretely wavelength-stepped pulses from a short fiber cavity. Pulses with different wavelengths are split and combined by standard wavelength division multiplexers with fiber delay lines. As a proof of concept, we demonstrate a laser using an erbium doped fiber amplifier and commercially available wavelength-division multiplexers with wavelength spacing of 0.8 nm. The results show simultaneous mode-locking at three different wavelengths. Laser output parameters in time domain, optical and radio frequency spectral domain, and the noise characteristics are presented. Suggestions for the improved design are discussed.

  12. Development of an underwater high sensitivity Cherenkov detector: Sea Urchin

    International Nuclear Information System (INIS)

    Camerini, U.; McGibney, D.; Roberts, A.

    1982-01-01

    The need for a high gain, high sensitivity Cherenkov light sensor to be used in a deep underwater muon and neutrino detector (DUMAND) array has led to the design of the Sea Urchin detector. In this design a spherical photocathode PMTis optically coupled through a glass hemisphere to a large number of glass spines, each of which is filled with a wavelength-shifting (WLS) solution of a high quantum efficiency phosphor. The Cherenkov radiation is absorbed in the spine, isotropically re-radiated at a longer wavelength, and a fraction of the fluorescent light is internally reflected in the spine, and guided to the photomultiplier concentrically located in the glass hemisphere. Experiments measuring the optical characteristics of the spines and computer programs simulating light transformation and detection cross sections are described. Overall optical gains in the range 5-10 are achieved. The WLS solution is inexpensive, and may have other applications. (orig.)

  13. CMS Hadronic EndCap Calorimeter Upgrade R&D Studies

    CERN Document Server

    Akgun, Ugur; Onel, Yasar

    2012-01-01

    Due to an expected increase in radiation damage in LHC, we propose to replace the active material of the CMS Hadronic EndCap calorimeters with radiation hard quartz plate. Quartz is proven to be radiation hard with radiation damage tests using electron, proton, neutron and gamma beams. However, the light produced in quartz is from Cerenkov process, which yields drastically fewer photons than scintillators. To increase the light collection efficiency we pursue two separate methods: First method: use wavelength shifting (WLS) fibers, which have been shown to collect efficiently the Cerenkov light generated in quartz plates. A quartz plate calorimeter prototype with WLS fibers has been constructed and tested at CERN that shows this method is feasible. Second proposed solution is to treat the quartz plates with radiation hard wavelength shifters, p-terphenyl, doped zinc oxide, or doped CdS. Another calorimeter prototype has been constructed with p-terphenyl deposited quartz plates, and showed superior calorimeter...

  14. Continuous Faraday measurement of spin precession without light shifts

    Science.gov (United States)

    Jasperse, M.; Kewming, M. Â. J.; Fischer, S. Â. N.; Pakkiam, P.; Anderson, R. Â. P.; Turner, L. Â. D.

    2017-12-01

    We describe a dispersive Faraday optical probe of atomic spin which performs a weak measurement of spin projection of a quantum gas continuously for more than one second. To date, focusing bright far-off-resonance probes onto quantum gases has proved invasive due to strong scalar and vector light shifts exerting dipole and Stern-Gerlach forces. We show that tuning the probe near the magic-zero wavelength at 790 nm between the fine-structure doublet of 87Rb cancels the scalar light shift, and careful control of polarization eliminates the vector light shift. Faraday rotations due to each fine-structure line reinforce at this wavelength, enhancing the signal-to-noise ratio for a fixed rate of probe-induced decoherence. Using this minimally invasive spin probe, we perform microscale atomic magnetometry at high temporal resolution. Spectrogram analysis of the Larmor precession signal of a single spinor Bose-Einstein condensate measures a time-varying magnetic field strength with 1 μ G accuracy every 5 ms; or, equivalently, makes more than 200 successive measurements each at 10 pT /√{Hz } sensitivity.

  15. S – C – L triple wavelength superluminescent source based on an ultra-wideband SOA and FBGs

    International Nuclear Information System (INIS)

    Ahmad, H; Zulkifli, M Z; Hassan, N A; Muhammad, F D; Harun, S W

    2013-01-01

    We propose and demonstrate a wide-band semiconductor optical amplifier (SOA) based triple-wavelength superluminescent source with the output in the S-, C- and L-band regions. The proposed systems uses an ultra-wideband SOA with an amplification range from 1440 to 1620 nm as the linear gain medium. Three fibre Bragg gratings (FBGs) with centre wavelengths of 1500, 1540 and 1580 nm are used to generate the lasing wavelengths in the S-, Cand L-bands respectively, while a variable optical attenuator is used to finely balance the optical powers of the lasing wavelengths. The ultra-wideband SOA generates an amplified spontaneous emission (ASE) spectrum with a peak power of -33 dBm at the highest SOA drive current, and also demonstrates a down-shift in the centre wavelength of the generated spectrum due to the spatial distribution of the carrier densities. The S-band wavelength is the dominant wavelength at high drive currents, with an output power of -6 dBm as compared to the C- and L-bands, which only have powers of -11 and -10 dBm, respectively. All wavelengths have a high average signal-to-noise ratio more than 60 dB at the highest drive current of 390 mA, and the system also shows a high degree of stability, with power fluctuations of less than 3 dB within 70 min. The proposed system can find many applications where a wide-band and stable laser source is crucial, such as in communications and sensing. (control of laser radiation parameters)

  16. S – C – L triple wavelength superluminescent source based on an ultra-wideband SOA and FBGs

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, H; Zulkifli, M Z; Hassan, N A; Muhammad, F D; Harun, S W [Photonics Research Center (Department of Physics), University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2013-10-31

    We propose and demonstrate a wide-band semiconductor optical amplifier (SOA) based triple-wavelength superluminescent source with the output in the S-, C- and L-band regions. The proposed systems uses an ultra-wideband SOA with an amplification range from 1440 to 1620 nm as the linear gain medium. Three fibre Bragg gratings (FBGs) with centre wavelengths of 1500, 1540 and 1580 nm are used to generate the lasing wavelengths in the S-, Cand L-bands respectively, while a variable optical attenuator is used to finely balance the optical powers of the lasing wavelengths. The ultra-wideband SOA generates an amplified spontaneous emission (ASE) spectrum with a peak power of -33 dBm at the highest SOA drive current, and also demonstrates a down-shift in the centre wavelength of the generated spectrum due to the spatial distribution of the carrier densities. The S-band wavelength is the dominant wavelength at high drive currents, with an output power of -6 dBm as compared to the C- and L-bands, which only have powers of -11 and -10 dBm, respectively. All wavelengths have a high average signal-to-noise ratio more than 60 dB at the highest drive current of 390 mA, and the system also shows a high degree of stability, with power fluctuations of less than 3 dB within 70 min. The proposed system can find many applications where a wide-band and stable laser source is crucial, such as in communications and sensing. (control of laser radiation parameters)

  17. Noninvasive diagnosis of oral cancer by Stokes shift spectroscopy

    Science.gov (United States)

    Ebenezar, Jeyasingh; Ganesan, Singaravelu; Aruna, Prakasrao; Muralinaidu, Radhakrishnan

    2014-03-01

    The objective of this study is to evaluate the diagnostic potential of stokes shift (SS) spectroscopy (S3) for normal, precancer and cancerous oral lesions in vivo. The SS spectra were recorded in the 250 - 650 nm spectral range by simultaneously scanning both the excitation and emission wavelengths while keeping a fixed wavelength interval Δλ=20 nm between them. Characteristic, highly resolved peaks and significant spectral differences between normal and different pathological oral lesions observed around 300, 355, 395, and 420 nm which are attributed to tryptophan, collagen, and NADH respectively. Using S3 technique one can obtain the key fluorophores in a single scan and hence they can be targeted as a tumor markers in this study. In order to quantify the altered spectral differences between normal and different pathological oral lesions are verified by different ratio parameters.

  18. First ever full size CdTE luminescent down-shifting module

    NARCIS (Netherlands)

    Ross, D.; Alonso-Alvarez, D.; Fritsche, J.; Bauer, M.; Debije, M.G.; Fifield, R.M.; Richards, B.S.

    2012-01-01

    For the first time a luminescent down-shifting (LDS) layer has been applied to a full size PV module to improve its short-wavelength response. An average 4.3% relative increase in the short-circuit current density (JSC) was recorded for the Calyxo cadmium telluride (CdTe) modules after the best LDS

  19. How to distinguish elastically scattered light from Stokes shifted light for solid-state lighting?

    NARCIS (Netherlands)

    Meretska, Maryna; Lagendijk, Aart; Thyrrestrup Nielsen, Henri; Mosk, Allard; IJzerman, W.L.; Vos, Willem L.

    2016-01-01

    We have studied the transport of light through phosphor diffuser plates that are used in commercial solid-state lighting modules (Fortimo). These polymer plates contain YAG:Ce+3phosphor particles that both elastically scatter and Stokes shift light in the visible wavelength range (400–700 nm). We

  20. Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

    Science.gov (United States)

    Maeda, Y

    1994-08-10

    An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

  1. Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

    DEFF Research Database (Denmark)

    Min, Rui; Marques, Carlos; Bang, Ole

    2018-01-01

    We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different...

  2. Work shifts in Emergency Medicine

    Directory of Open Access Journals (Sweden)

    Roberto Recupero

    2007-06-01

    Full Text Available Emergency Medicine is known as a high stress specialty. The adverse effect of constantly rotating shifts is the single most important reason given for premature attrition from the field. In this work problems tied with night shift work will be taken into account and some solutions to reduce the impact of night work on the emergency physicians will be proposed.

  3. Flexible Schedules and Shift Work.

    Science.gov (United States)

    Beers, Thomas M.

    2000-01-01

    Flexible work hours have gained prominence, as more than 25 million workers (27.6% of all full-time workers) can now vary their schedules. However, there has been little change since the mid-1980s in the proportion who work a shift other than a regular daytime shift. (JOW)

  4. Stresses and Temperature Stability of Dense Wavelength Division Multiplexing Filters Prepared by Reactive Ion-Assisted E-Gun Evaporation

    Science.gov (United States)

    Wei, Chao-Tsang; Shieh, Han-Ping D.

    2005-10-01

    In this paper, we report the in situ measurement of the temperature stability of narrow-band-pass filters on different types of substrate, for dense wavelength division multiplexing (DWDM) filters in optical-fiber transmission systems. The DWDM filters were designed as all-dielectric Fabry-Perot filters and fabricated by reactive ion-assisted deposition. Ta2O5 and SiO2 were used as high- and low-refractive-index layers, respectively, for constructing the DWDM filters. The accuracy and stability of the coating process were evaluated for fabricating the DWDM filters for the temperature stability of the center wavelength. The center wavelength shift was determined to be greatly dependent on the coefficient of thermal expansion of the substrate on which the filter is deposited.

  5. Soliton self-frequency shift controlled by a weak seed laser in tellurite photonic crystal fibers.

    Science.gov (United States)

    Liu, Lai; Meng, Xiangwei; Yin, Feixiang; Liao, Meisong; Zhao, Dan; Qin, Guanshi; Ohishi, Yasutake; Qin, Weiping

    2013-08-01

    We report the first demonstration of soliton self-frequency shift (SSFS) controlled by a weak continuous-wave (CW) laser, from a tellurite photonic crystal fiber pumped by a 1560 nm femtosecond fiber laser. The control of SSFS is performed by the cross-gain modulation of the 1560 nm femtosecond laser. By varying the input power of the weak CW laser (1560 nm) from 0 to 1.17 mW, the soliton generated in the tellurite photonic crystal fiber blue shifts from 1935 to 1591 nm. The dependence of the soliton wavelength on the operation wavelength of the weak CW laser is also measured. The results show the CW laser with a wavelength tunable range of 1530-1592 nm can be used to control the SSFS generation.

  6. Metasurface axicon lens design at visible wavelengths

    Science.gov (United States)

    Alyammahi, Saleimah; Zhan, Qiwen

    2017-08-01

    The emerging field of metasurfaces is promising to realize novel optical devices with miniaturized flat format and added functionalities. Metasurfaces have been demonstrated to exhibit full control of amplitude, phase and polarization of electromagnetic waves. Using the metasurface, the wavefront of light can be manipulated permitting new functionalities such as focusing and steering of the beams and imaging. One optical component which can be designed using metasurfaces is the axicon. Axicons are conical lenses used to convert Gaussian beams into nondiffraction Bessel beams. These unique devices are utilized in different applications ranging from optical trapping and manipulation, medical imaging, and surgery. In this work, we study axicon lens design comprising of planar metasurfaces which generate non-diffracting Bessel beams at visible wavelengths. Dielectric metasurfaces have been used to achieve high efficiency and low optical loss. We measured the spot size of the resulted beams at different planes to demonstrate the non-diffraction properties of the resulted beams. We also investigated how the spot size is influenced by the axicon aperture. Furthermore, we examined the achromatic properties of the designed axicon. Comparing with the conventional lens, the metasurface axicon lens design enables the creation of flat optical device with wide range of depth of focus along its optical axis.

  7. Spectral reconstruction for shifted-excitation Raman difference spectroscopy (SERDS).

    Science.gov (United States)

    Guo, Shuxia; Chernavskaia, Olga; Popp, Jürgen; Bocklitz, Thomas

    2018-08-15

    Fluorescence emission is one of the major obstacles to apply Raman spectroscopy in biological investigations. It is usually several orders more intense than Raman scattering and hampers further analysis. In cases where the fluorescence emission is too intense to be efficiently removed via routine mathematical baseline correction algorithms, an alternative approach is needed. One alternative approach is shifted-excitation Raman difference spectroscopy (SERDS), where two Raman spectra are recorded with two slightly different excitation wavelengths. Ideally, the fluorescence emission at the two excitations does not change while the Raman spectrum shifts according to the excitation wavelength. Hence the fluorescence is removed in the difference of the two recorded Raman spectra. For better interpretability a spectral reconstruction procedure is necessary to recover the fluorescence-free Raman spectrum. This is challenging due to the intensity variations between the two recorded Raman spectra caused by unavoidable experimental changes as well as the presence of noise. Existent approaches suffer from drawbacks like spectral resolution loss, fluorescence residual, and artefacts. In this contribution, we proposed a reconstruction method based on non-negative least squares (NNLS), where the intensity variations between the two measurements are utilized in the reconstruction model. The method achieved fluorescence-free reconstruction on three real-world SERDS datasets without significant information loss. Thereafter, we quantified the performance of the reconstruction based on artificial datasets from four aspects: reconstructed spectral resolution, precision of reconstruction, signal-to-noise-ratio (SNR), and fluorescence residual. The artificial datasets were constructed with varied Raman to fluorescence intensity ratio (RFIR), SNR, full-width at half-maximum (FWHM), excitation wavelength shift, and fluorescence variation between the two spectra. It was demonstrated that

  8. Wavelength encoding technique for particle analyses in hematology analyzer

    Science.gov (United States)

    Rongeat, Nelly; Brunel, Patrick; Gineys, Jean-Philippe; Cremien, Didier; Couderc, Vincent; Nérin, Philippe

    2011-07-01

    The aim of this study is to combine multiple excitation wavelengths in order to improve accuracy of fluorescence characterization of labeled cells. The experimental demonstration is realized with a hematology analyzer based on flow cytometry and a CW laser source emitting two visible wavelengths. A given optical encoding associated to each wavelength allows fluorescence identification coming from specific fluorochromes and avoiding the use of noisy compensation method.

  9. Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2

    International Nuclear Information System (INIS)

    McConnell, Gail; Riis, Erling

    2004-01-01

    We report on a novel and compact reliable laser source capable of short-wavelength two-photon laser scanning fluorescence microscopy based on soliton self-frequency shift effects in photonic crystal fibre. We demonstrate the function of the system by performing two-photon microscopy of smooth muscle cells and cardiac myocytes from the rat pulmonary vein and Chinese hamster ovary cells loaded with the fluorescent calcium indicator fura-2/AM

  10. All optical wavelength conversion and parametric amplification in Ti:PPLN channel waveguides for telecommunication applications

    Energy Technology Data Exchange (ETDEWEB)

    Nouroozi, Rahman

    2010-10-19

    Efficient ultra-fast integrated all-optical wavelength converters and parametric amplifiers transparent to the polarization, phase, and modulation-level and -format are investigated. The devices take advantage of the optical nonlinearity of Ti:PPLN waveguides exploiting difference frequency generation (DFG). In a DFG, the signal ({lambda}{sub s}) is mixed with a pump ({lambda}{sub p}) to generate a wavelength shifted idler (1/{lambda}{sub i}=1/{lambda}{sub p}-1/{lambda}{sub s}). Efficient generation of the pump in Ti:PPLN channel guides is investigated using different approaches. In the waveguide resonators, first a resonance of the fundamental wave alone is considered. It is shown that the maximum power enhancement of the fundamental wave, and therefore the maximum second-harmonic generation (SHG) efficiency, can be achieved with low loss matched resonators. By this way, SHG efficiency of {proportional_to}10300%/W (10.3 %/mW) has been achieved in a 65 mm long waveguide resonator. Its operation for cSHG/DFG requires narrowband reflector for fundamental wave only. Thus, the SH (pump) wave resonator is investigated. The SH-wave resonator enhances the intracavity SH power only. Based on this scheme, an improvement of {proportional_to}10 dB for cSHG/DFG based wavelength conversion efficiency has been achieved with 50 mW of coupled fundamental power in a 30 mm long Ti:PPLN. However, operation was limited to relatively small fundamental power levels (<50 mW) due to the onset of photorefractive instabilities destroying the cavity stabilization. The cSHG/DFG efficiency can be considerably improved by using a double-pass configuration in which all the interacting waves were reflected by a broadband dielectric mirror deposited on the one endface of the waveguide. Three different approaches are investigated and up to 9 dB improvement of the wavelength conversion efficiency in comparison with the single-pass configuration is achieved. Polarization-insensitive wavelength

  11. Performance evaluation of distributed wavelength assignment in WDM optical networks

    Science.gov (United States)

    Hashiguchi, Tomohiro; Wang, Xi; Morikawa, Hiroyuki; Aoyama, Tomonori

    2004-04-01

    In WDM wavelength routed networks, prior to a data transfer, a call setup procedure is required to reserve a wavelength path between the source-destination node pairs. A distributed approach to a connection setup can achieve a very high speed, while improving the reliability and reducing the implementation cost of the networks. However, along with many advantages, several major challenges have been posed by the distributed scheme in how the management and allocation of wavelength could be efficiently carried out. In this thesis, we apply a distributed wavelength assignment algorithm named priority based wavelength assignment (PWA) that was originally proposed for the use in burst switched optical networks to the problem of reserving wavelengths of path reservation protocols in the distributed control optical networks. Instead of assigning wavelengths randomly, this approach lets each node select the "safest" wavelengths based on the information of wavelength utilization history, thus unnecessary future contention is prevented. The simulation results presented in this paper show that the proposed protocol can enhance the performance of the system without introducing any apparent drawbacks.

  12. Span Restoration in Optical Networks with Limited Wavelength Conversion

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Buron, Jakob Due; Andriolli, N

    2007-01-01

    Next generation optical networks provide functionalities to dynamically provision and recover connections, while emerging technologies allow for the conversion between wavelengths. These devices are however expensive and hence it is likely that only few are deployed throughout the network...... converter-saving wavelength assignment in GMPLS networks. The converter saving property of the Suggested Vector is particularly desirable in span restoration, where the pre-failure path stubs have to be merged to the restoration path at the failure-adjacent nodes. In order to avoid wavelength conversion....... Furthermore, we describe different scenarios to extend the suggested vector wavelength assignment scheme to multi-domain networks with focus on span restoration....

  13. Tapered amplifier laser with frequency-shifted feedback

    Directory of Open Access Journals (Sweden)

    A. Bayerle, S. Tzanova, P. Vlaar, B. Pasquiou, F. Schreck

    2016-10-01

    Full Text Available We present a frequency-shifted feedback (FSF laser based on a tapered amplifier. The laser operates as a coherent broadband source with up to 370GHz spectral width and 2.3us coherence time. If the FSF laser is seeded by a continuous-wave laser a frequency comb spanning the output spectrum appears in addition to the broadband emission. The laser has an output power of 280mW and a center wavelength of 780nm. The ease and flexibility of use of tapered amplifiers makes our FSF laser attractive for a wide range of applications, especially in metrology.

  14. Software for imaging phase-shift interference microscope

    Science.gov (United States)

    Malinovski, I.; França, R. S.; Couceiro, I. B.

    2018-03-01

    In recent years absolute interference microscope was created at National Metrology Institute of Brazil (INMETRO). The instrument by principle of operation is imaging phase-shifting interferometer (PSI) equipped with two stabilized lasers of different colour as traceable reference wavelength sources. We report here some progress in development of the software for this instrument. The status of undergoing internal validation and verification of the software is also reported. In contrast with standard PSI method, different methodology of phase evaluation is applied. Therefore, instrument specific procedures for software validation and verification are adapted and discussed.

  15. Critical de Broglie wavelength in superconductors

    Science.gov (United States)

    Talantsev, E. F.

    2018-03-01

    There are growing numbers of experimental evidences that the self-field critical currents, Jc(sf,T), are a new instructive tool to investigate fundamental properties of superconductors ranging from atomically thin films [M. Liao et al., Nat. Phys. 6 (2018), https://doi.org/10.1038/s41567-017-0031-6; E. F. Talantsev et al., 2D Mater. 4 (2017) 025072; A. Fete et al., Appl. Phys. Lett. 109 (2016) 192601] to millimeter-scale samples [E. F. Talantsev et al., Sci. Rep. 7 (2017) 10010]. The basic empirical equation which quantitatively accurately described experimental Jc(sf,T) was proposed by Talantsev and Tallon [Nat. Commun. 6 (2015) 7820] and it was the relevant critical field (i.e. thermodynamic field, Bc, for type-I and lower critical field, Bc1, for type-II superconductors) divided by the London penetration depth, λL. In this paper, we report new findings relating to this empirical equation. It is that the critical wavelength of the de Broglie wave, λdB,c, of the superconducting charge carrier which within a numerical pre-factor is equal to the largest of two characteristic lengths of Ginzburg-Landau theory, i.e. the coherence length, ξ, for type-I superconductors or the London penetration depth, λL, for type-II superconductors. We also formulate a microscopic criterion for the onset of dissipative transport current flow: ps ṡ 2ṡλL ln(1+2ṡ(λL ξ )) ≥ 1 2 ṡ ( h 2π), where ps is the charge carrier momentum, h is Planck’s constant and the inequality sign “ <” is reserved for the dissipation-free flow.

  16. Growth of Au nanoparticle films and the effect of nanoparticle shape on plasmon peak wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Horikoshi, S., E-mail: horikoshi@sstl.info; Matsumoto, N.; Kato, T. [Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-8656 (Japan); Omata, Y. [Application and Technical Support, Elionix, Inc., 3-7-6 Motoyokoyama Hachioji, Tokyo 192-0063 (Japan)

    2014-05-21

    Metal nanoparticles (NPs) exhibit localized surface plasmon resonance (LSPR) and thus have potential for use in a wide range of applications. A facile technique for the preparation of NP films using an electron-cyclotron-resonance plasma sputtering method without a dewetting process is described. Field emission scanning electron microscopy (FE-SEM) observations revealed that the Au NPs grew independently as island-like particles during the first stage of sputtering and then coalesced with one another as sputtering time increased to ultimately form a continuous film. A plasmon absorption peak was observed via optical measurement of absorption efficiency. The LSPR peak shifted toward longer wavelengths (red shift) with an increase in sputtering time. The cause of this plasmon peak shift was theoretically investigated using the finite-difference time-domain calculation method. A realistic statistical distribution of the particle shapes based on FE-SEM observations was applied for the analysis, which has not been previously reported. It was determined that the change in the shape of the NPs from spheroidal to oval or slender due to coalescence with neighbouring NPs caused the LSPR peak shift. These results may enable the design of LSPR devices by controlling the characteristics of the nanoparticles, such as their size, shape, number density, and coverage.

  17. Growth of Au nanoparticle films and the effect of nanoparticle shape on plasmon peak wavelength

    Science.gov (United States)

    Horikoshi, S.; Matsumoto, N.; Omata, Y.; Kato, T.

    2014-05-01

    Metal nanoparticles (NPs) exhibit localized surface plasmon resonance (LSPR) and thus have potential for use in a wide range of applications. A facile technique for the preparation of NP films using an electron-cyclotron-resonance plasma sputtering method without a dewetting process is described. Field emission scanning electron microscopy (FE-SEM) observations revealed that the Au NPs grew independently as island-like particles during the first stage of sputtering and then coalesced with one another as sputtering time increased to ultimately form a continuous film. A plasmon absorption peak was observed via optical measurement of absorption efficiency. The LSPR peak shifted toward longer wavelengths (red shift) with an increase in sputtering time. The cause of this plasmon peak shift was theoretically investigated using the finite-difference time-domain calculation method. A realistic statistical distribution of the particle shapes based on FE-SEM observations was applied for the analysis, which has not been previously reported. It was determined that the change in the shape of the NPs from spheroidal to oval or slender due to coalescence with neighbouring NPs caused the LSPR peak shift. These results may enable the design of LSPR devices by controlling the characteristics of the nanoparticles, such as their size, shape, number density, and coverage.

  18. Procedure to decouple reflectance and down-shifting effects in luminescent down-shifting enhanced photovoltaics.

    Science.gov (United States)

    Gabr, Ahmed M; Walker, Alexandre W; Wilkins, Matthew M; Kleiman, Rafael; Hinzer, Karin

    2017-06-12

    The down-shifting (DS) process is a purely optical approach used to improve the short-wavelength response of a solar cell by shifting high-energy photons to the visible range, which can be more efficiently absorbed by the solar cell. In addition to the DS effect, coupling a DS layer to the top surface of a solar cell results in a change in surface reflectance. The two effects are intermixed and therefore, usually reported as a single effect. Here we propose a procedure to decouple the two effects. Analytical equations are derived to decouple the two effects, that consider the experimentally measured quantum efficiency of the solar cell with and without the DS layer, in addition to transfer matrix simulations of the parasitic absorption in the device structure. In this work, an overall degradation of 0.46 mA/cm 2 is observed when adding a DS layer composed of silicon nanocrystals embedded in a quartz matrix to a silicon solar cell of 11% baseline efficiency. To fully understand the contribution from each effect, the surface reflectance and DS effects are decoupled and quantified using the described procedure. We observe an enhancement of 0.27 mA/cm 2 in short-circuit current density due to the DS effect, while the surface reflectance effect leads to a degradation of 0.73 mA/cm 2 in short-circuit current density.

  19. Broadband and high efficiency all-dielectric metasurfaces for wavefront steering with easily obtained phase shift

    Science.gov (United States)

    Yang, Hui; Deng, Yan

    2017-12-01

    All-dielectric metasurfaces for wavefront deflecting and optical vortex generating with broadband and high efficiency are demonstrated. The unit cell of the metasurfaces is optimized to function as a half wave-plate with high polarization conversion efficiency (94%) and transmittance (94.5%) at the telecommunication wavelength. Under such a condition, we can get rid of the complicated parameter sweep process for phase shift selecting. Hence, a phase coverage ranges from 0 to 2 π can be easily obtained by introducing the Pancharatnam-Berry phase. Metasurfaces composed of the two pre-designed super cells are demonstrated for optical beam deflecting and vortex beam generating. It is found that the metasurfaces with more phase shift sampling points (small phase shift increment) exhibit better performance. Moreover, optical vortex beams can be generated by the designed metasurfaces within a wavelength range of 200 nm. These results will provide a viable route for designing broadband and high efficiency devices related to phase modulation.

  20. Compactly packaged monolithic four-wavelength VCSEL array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport.

    Science.gov (United States)

    Lee, Eun-Gu; Mun, Sil-Gu; Lee, Sang Soo; Lee, Jyung Chan; Lee, Jong Hyun

    2015-01-12

    We report a cost-effective transmitter optical sub-assembly using a monolithic four-wavelength vertical-cavity surface-emitting laser (VCSEL) array with 100-GHz wavelength spacing for future-proof mobile fronthaul transport using the data rate of common public radio interface option 6. The wavelength spacing is achieved using selectively etched cavity control layers and fine current adjustment. The differences in operating current and output power for maintaining the wavelength spacing of four VCSELs are fiber without any dispersion-compensation techniques.

  1. Highly accurate Michelson type wavelength meter that uses a rubidium stabilized 1560 nm diode laser as a wavelength reference

    International Nuclear Information System (INIS)

    Masuda, Shin; Kanoh, Eiji; Irisawa, Akiyoshi; Niki, Shoji

    2009-01-01

    We investigated the accuracy limitation of a wavelength meter installed in a vacuum chamber to enable us to develop a highly accurate meter based on a Michelson interferometer in 1550 nm optical communication bands. We found that an error of parts per million order could not be avoided using famous wavelength compensation equations. Chromatic dispersion of the refractive index in air can almost be disregarded when a 1560 nm wavelength produced by a rubidium (Rb) stabilized distributed feedback (DFB) diode laser is used as a reference wavelength. We describe a novel dual-wavelength self-calibration scheme that maintains high accuracy of the wavelength meter. The method uses the fundamental and second-harmonic wavelengths of an Rb-stabilized DFB diode laser. Consequently, a highly accurate Michelson type wavelength meter with an absolute accuracy of 5x10 -8 (10 MHz, 0.08 pm) over a wide wavelength range including optical communication bands was achieved without the need for a vacuum chamber.

  2. Excitation wavelength selection for quantitative analysis of carotenoids in tomatoes using Raman spectroscopy.

    Science.gov (United States)

    Hara, Risa; Ishigaki, Mika; Kitahama, Yasutaka; Ozaki, Yukihiro; Genkawa, Takuma

    2018-08-30

    The difference in Raman spectra for different excitation wavelengths (532 nm, 785 nm, and 1064 nm) was investigated to identify an appropriate wavelength for the quantitative analysis of carotenoids in tomatoes. For the 532 nm-excited Raman spectra, the intensity of the peak assigned to the carotenoid has no correlation with carotenoid concentration, and the peak shift reflects carotenoid composition changing from lycopene to β-carotene and lutein. Thus, 532 nm-excited Raman spectra are useful for the qualitative analysis of carotenoids. For the 785 nm- and 1064 nm-excited Raman spectra, the peak intensity of the carotenoid showed good correlation with carotenoid concentration; thus, regression models for carotenoid concentration were developed using these Raman spectra and partial least squares regression. A regression model designed using the 785 nm-excited Raman spectra showed a better result than the 532 nm- and 1064 nm-excited Raman spectra. Therefore, it can be concluded that 785 nm is the most suitable excitation wavelength for the quantitative analysis of carotenoid concentration in tomatoes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Enhanced Deformation of Azobenzene-Modified Liquid Crystal Polymers under Dual Wavelength Exposure: A Photophysical Model

    Science.gov (United States)

    Liu, Ling; Onck, Patrick R.

    2017-08-01

    Azobenzene-embedded liquid crystal polymers can undergo mechanical deformation in response to ultraviolet (UV) light. The natural rodlike trans state azobenzene absorbs UV light and isomerizes to a bentlike cis state, which disturbs the order of the polymer network, leading to an anisotropic deformation. The current consensus is that the magnitude of the photoinduced deformation is related to the statistical building up of molecules in the cis state. However, a recent experimental study [Liu and Broer, Nat. Commun. 6 8334 (2015)., 10.1038/ncomms9334] shows that a drastic (fourfold) increase of the photoinduced deformation can be generated by exposing the samples simultaneously to 365 nm (UV) and 455 nm (visible) light. To elucidate the physical mechanism that drives this increase, we develop a two-light attenuation model and an optomechanical constitutive relation that not only accounts for the statistical accumulation of cis azobenzenes, but also for the dynamic trans-cis-trans oscillatory isomerization process. Our experimentally calibrated model predicts that the optimal single-wavelength exposure is 395 nm light, a pronounced shift towards the visible spectrum. In addition, we identify a range of optimal combinations of two-wavelength lights that generate a favorable response for a given amount of injected energy. Our model provides mechanistic insight into the different (multi)wavelength exposures used in experiments and, at the same time, opens new avenues towards enhanced, multiwavelength optomechanical behavior.

  4. Effect of algae and water on water color shift

    Science.gov (United States)

    Yang, Shengguang; Xia, Daying; Yang, Xiaolong; Zhao, Jun

    1991-03-01

    This study showed that the combined effect of absorption of planktonic algae and water on water color shift can be simulated approximately by the exponential function: Log( E {100cm/ W }+ E {100cm/ Xch1})=0.002λ-2.5 where E {100/cm W }, E {100cm/ Xchl} are, respectively, extinction coefficients of seawater and chlorophyll—a (concentration is equal to X mg/m3), and λ (nm) is wavelength. This empirical regression equation is very useful for forecasting the relation between water color and biomass in water not affected by terrigenous material. The main factor affecting water color shift in the ocean should be the absorption of blue light by planktonic algae.

  5. Wavelength properties of DCG holograms under the conditions of different temperature and humidity

    Science.gov (United States)

    Liu, Yujie; Li, Wenqiang; Ding, Quanxin; Yan, Zhanjun

    2014-12-01

    Holograms recorded in dichromated gelatin (DCG) are usually sealed with a glass plate cemented with an epoxy glue to protect the holograms from moisture in the environment. An investigation of the wavelength properties of sealed DCG holograms had been carried out paying attention to holograms which were exposed to different temperature and humidity environment in this work. The investigation had revealed that (a) exposing the sealed DCG holograms to high relative humidity (RH=98%) environment or immersing them in room-temperature water for 20 hours can not affect the holograms; (b) the sealed DCG holograms can be used at temperature below 50°C without showing undue detrimental effects regarding their optical properties; (c) the peak wavelength of sealed DCG holograms can cause blue shift of several nanometers at 70°C~85°C and the velocity of blue shift is proportional to the environmental temperature; (d) the holograms can be destroyed at 100° or above. The experimental results above will be analyzed and discussed in this paper. A method to improve the stability of sealed DCG holograms is proposed: baking the sealed DCG holograms at proper temperature (e.g., 85°C in this study).

  6. Interband emission energy in a dilute nitride quaternary semiconductor quantum dot for longer wavelength applications

    Science.gov (United States)

    Mageshwari, P. Uma; Peter, A. John; Lee, Chang Woo; Duque, C. A.

    2016-07-01

    Excitonic properties are studied in a strained Ga1-xInxNyAs1-y/GaAs cylindrical quantum dot. The optimum condition for the desired band alignment for emitting wavelength 1.55 μm is investigated using band anticrossing model and the model solid theory. The band gap and the band discontinuities of a Ga1-xInxNyAs1-y/GaAs quantum dot on GaAs are computed with the geometrical confinement effect. The binding energy of the exciton, the oscillator strength and its radiative life time for the optimum condition are found taking into account the spatial confinement effect. The effects of geometrical confinement and the nitrogen incorporation on the interband emission energy are brought out. The result shows that the desired band alignment for emitting wavelength 1.55 μm is achieved for the inclusion of alloy contents, y=0.0554% and x=0.339% in Ga1-xInxNyAs1-y/GaAs quantum dot. And the incorporation of nitrogen and indium shows the red-shift and the geometrical confinement shows the blue-shift. And it can be applied for fibre optical communication networks.

  7. Self-phase modulation enabled, wavelength-tunable ultrafast fiber laser sources: an energy scalable approach.

    Science.gov (United States)

    Liu, Wei; Li, Chen; Zhang, Zhigang; Kärtner, Franz X; Chang, Guoqing

    2016-07-11

    We propose and demonstrate a new approach to implement a wavelength-tunable ultrafast fiber laser source suitable for multiphoton microscopy. We employ fiber-optic nonlinearities to broaden a narrowband optical spectrum generated by an Yb-fiber laser system and then use optical bandpass filters to select the leftmost or rightmost spectral lobes from the broadened spectrum. Detailed numerical modeling shows that self-phase modulation dominates the spectral broadening, self-steepening tends to blue shift the broadened spectrum, and stimulated Raman scattering is minimal. We also find that optical wave breaking caused by fiber dispersion slows down the shift of the leftmost/rightmost spectral lobes and therefore limits the wavelength tuning range of the filtered spectra. We show both numerically and experimentally that shortening the fiber used for spectral broadening while increasing the input pulse energy can overcome this dispersion-induced limitation; as a result, the filtered spectral lobes have higher power, constituting a powerful and practical approach for energy scaling the resulting femtosecond sources. We use two commercially available photonic crystal fibers to verify the simulation results. More specific, use of 20-mm fiber NL-1050-ZERO-2 enables us to implement an Yb-fiber laser based ultrafast source, delivering femtosecond (70-120 fs) pulses tunable from 825 nm to 1210 nm with >1 nJ pulse energy.

  8. Controlling the emission wavelength in group III-V semiconductor laser diodes

    KAUST Repository

    Ooi, Boon S.

    2016-12-29

    Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III-V semiconductor quantum wells. The group III-V semiconductor can include AlSb, AlAs, Aln, AlP, BN, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, and InP, and group III-V ternary semiconductors alloys such as AlxGai.xAs. The methods can results in a blue shifting of about 20 meV to 350 meV, which can be used for example to make group III-V semiconductor quantum well laser diodes with an emission that is orange or yellow. Methods of making semiconductor quantum well laser diodes and semiconductor quantum well laser diodes made therefrom are also provided.

  9. Extended averaging phase-shift schemes for Fizeau interferometry on high-numerical-aperture spherical surfaces

    Science.gov (United States)

    Burke, Jan

    2010-08-01

    Phase-shifting Fizeau interferometry on spherical surfaces is impaired by phase-shift errors increasing with the numerical aperture, unless a custom optical set-up or wavelength shifting is used. This poses a problem especially for larger numerical apertures, and requires good error tolerance of the phase-shift method used; but it also constitutes a useful testing facility for phase-shift formulae, because a vast range of phase-shift intervals can be tested in a single measurement. In this paper I show how the "characteristic polynomials" method can be used to generate a phase-shifting method for the actual numerical aperture, and analyse residual cyclical phase errors by comparing a phase map from an interferogram with a few fringes to a phase mpa from a nulled fringe. Unrelated to the phase-shift miscalibration, thirdharmonic error fringes are found. These can be dealt with by changing the nominal phase shift from 90°/step to 60°/step and re-tailoring the evaluation formula for third-harmonic rejection. The residual error has the same frequency as the phase-shift signal itself, and can be removed by averaging measurements. Some interesting features of the characteristic polynomials for the averaged formulae emerge, which also shed some light on the mechanism that generates cyclical phase errors.

  10. Isolating long-wavelength fluctuation from structural relaxation in two-dimensional glass: cage-relative displacement

    Science.gov (United States)

    Shiba, Hayato; Keim, Peter; Kawasaki, Takeshi

    2018-03-01

    It has recently been revealed that long-wavelength fluctuation exists in two-dimensional (2D) glassy systems, having the same origin as that given by the Mermin-Wagner theorem for 2D crystalline solids. In this paper, we discuss how to characterise quantitatively the long-wavelength fluctuation in a molecular dynamics simulation of a lightly supercooled liquid. We employ the cage-relative mean-square displacement (MSD), defined on relative displacement to its cage, to quantitatively separate the long-wavelength fluctuation from the original MSD. For increasing system size the amplitude of acoustic long wavelength fluctuations not only increases but shifts to later times causing a crossover with structural relaxation of caging particles. We further analyse the dynamic correlation length using the cage-relative quantities. It grows as the structural relaxation becomes slower with decreasing temperature, uncovering an overestimation by the four-point correlation function due to the long-wavelength fluctuation. These findings motivate the usage of cage-relative MSD as a starting point for analysis of 2D glassy dynamics.

  11. Wavelength Conversion of a 9.35-Gb/s RZ OOK Signal in an InP Photonic Crystal Nanocavity

    DEFF Research Database (Denmark)

    Vukovic, Dragana; Yu, Yi; Heuck, Mikkel

    2014-01-01

    Wavelength conversion of a 10-Gb/s (9.35 Gb/s net rate) return-to-zero ON-OFF keying signal is demonstrated using a simple InP photonic crystal H0 nanocavity with Lorentzian line shape. The shifting of the resonance induced by the generation of free-carriers enables the pump intensity modulation...

  12. Wavelength conversion of a 40 Gb/s RZ-DPSK signal using four-wave mixing in a dispersion-flattened highly nonlinear photonic crystal fiber

    DEFF Research Database (Denmark)

    Andersen, Peter Andreas; Tokle, Torger; Geng, Yan

    2005-01-01

    Wavelength conversion of a 40-Gb/s return-to-zero differential phase-shift keying signal is demonstrated in a highly nonlinear photonic crystal fiber (HNL-PCF) for the first time. A conversion efficiency of -20 dB for a pump power of 23 dBm and a conversion bandwidth of 31 nm, essentially limited...

  13. Inequalities for scattering phase shifts

    International Nuclear Information System (INIS)

    Baumgartner, B.; Grosse, H.

    1985-01-01

    A recently developed method, which was used to derive bounds on energy levels, is applied to continuous spectra and gives relations between scattering phase shifts of various angular momenta. (Author)

  14. Isotope shifts in unstable nuclei

    International Nuclear Information System (INIS)

    Rebel, H.

    1980-05-01

    Current experimental investigations of isotope shifts in atomic spectra of unstable nuclei and the resulting information about size and shape of nuclei far off stability are discussed with reference to some representative examples. (orig.)

  15. Absorption spectrum of DNA for wavelengths greater than 300 nm

    International Nuclear Information System (INIS)

    Sutherland, J.C.; Griffin, K.P.

    1981-01-01

    Although DNA absorption at wavelengths greater than 300 nm is much weaker than that at shorter wavelengths, this absorption seems to be responsible for much of the biological damage caused by solar radiation of wavelengths less than 320 nm. Accurate measurement of the absorption spectrum of DNA above 300 nm is complicated by turbidity characteristic of concentrated solutions of DNA. We have measured the absorption spectra of DNA from calf thymus, Clostridium perfringens, Escherichia coli, Micrococcus luteus, salmon testis, and human placenta using procedures which separate optical density due to true absorption from that due to turbidity. Above 300 nm, the relative absorption of DNA increases as a function of guanine-cytosine content, presumably because the absorption of guanine is much greater than the absorption of adenine at these wavelengths. This result suggests that the photophysical processes which follow absorption of a long-wavelength photon may, on the average, differ from those induced by shorter-wavelength photons. It may also explain the lower quantum yield for the killing of cells by wavelengths above 300 nm compared to that by shorter wavelengths

  16. Technologies for all-optical wavelength conversion in DWDM networks

    DEFF Research Database (Denmark)

    Wolfson, David; Fjelde, Tina; Kloch, Allan

    2001-01-01

    Different techniques for all-optical wavelength conversion are reviewed and the advantages and disadvantages seen from a system perspective are highlighted. All-optical wavelength conversion will play a major role in making cost-effective network nodes in future high-speed WDM networks, where...

  17. Experimental determination of the slow-neutron wavelength distribution

    DEFF Research Database (Denmark)

    Lebech, Bente; Mikke, K.; Sledziewska-Blocka, D.

    1970-01-01

    Different experiments for determining the slow-neutron wavelength distribution in the region 227-3 meV have been carried out, and the results compared. It is concluded that the slow-neutron wave-length distribution can be determined accurately by elastic scattering on a pure incoherent or a pure...

  18. Emission wavelength of multilayer distributed feedback dye lasers

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron L. C.; Brøkner Christiansen, Mads

    2012-01-01

    Precise emission wavelength modeling is essential for understanding and optimization of distributed feedback (DFB) lasers. An analytical approach for determining the emission wavelength based on setting the propagation constant of the Bragg condition and solving for the resulting slab waveguide m...

  19. Sub-wavelength resonances in polygonal metamaterial cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2008-01-01

    It has been shown that the sub-wavelength resonances of circular MTM cylinders also occur for polygonal MTM cylinders. This is the case for lossless and non-dispersive cylinders as well as lossy and dispersive cylinders. The sub-wavelength resonances are thus not limited to structures of canonical...

  20. Systematic wavelength selection for improved multivariate spectral analysis

    Science.gov (United States)

    Thomas, Edward V.; Robinson, Mark R.; Haaland, David M.

    1995-01-01

    Methods and apparatus for determining in a biological material one or more unknown values of at least one known characteristic (e.g. the concentration of an analyte such as glucose in blood or the concentration of one or more blood gas parameters) with a model based on a set of samples with known values of the known characteristics and a multivariate algorithm using several wavelength subsets. The method includes selecting multiple wavelength subsets, from the electromagnetic spectral region appropriate for determining the known characteristic, for use by an algorithm wherein the selection of wavelength subsets improves the model's fitness of the determination for the unknown values of the known characteristic. The selection process utilizes multivariate search methods that select both predictive and synergistic wavelengths within the range of wavelengths utilized. The fitness of the wavelength subsets is determined by the fitness function F=.function.(cost, performance). The method includes the steps of: (1) using one or more applications of a genetic algorithm to produce one or more count spectra, with multiple count spectra then combined to produce a combined count spectrum; (2) smoothing the count spectrum; (3) selecting a threshold count from a count spectrum to select these wavelength subsets which optimize the fitness function; and (4) eliminating a portion of the selected wavelength subsets. The determination of the unknown values can be made: (1) noninvasively and in vivo; (2) invasively and in vivo; or (3) in vitro.

  1. Sub-wavelength metamaterial cylinders with multiple dipole resonances

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2009-01-01

    It has been shown that the sub-wavelength resonances of the individual MTM cylinders also occur for electrically small configurations combining 2 or 4 cylinders. For the 2-and 4-cylinder configurations the overall size is 1/20 and 1/12.5 of the smallest wavelength, respectively. These MTM...... configuration thus offer the possibility for multi-resonant electrically small configurations....

  2. Modulating wavelength discrimination in goldfish with ethambutol and stimulus intensity

    NARCIS (Netherlands)

    Sjoerdsma, T.; Kamermans, M.; Spekreijse, H.

    1996-01-01

    Wavelength discrimination in goldfish was measured behaviourally. Both acute application of ethambutol injected into the eye and chronic application by feeding the animals daily 25 mg ethambutol for 1 month had the same effect on wavelength discrimination in the range of 560-640 nm. This means that:

  3. Calibrated Phase-Shifting Digital Holographic Microscope Using a Sampling Moiré Technique

    Directory of Open Access Journals (Sweden)

    Peng Xia

    2018-05-01

    Full Text Available A calibrated phase-shifting digital holographic microscope system capable of improving the quality of reconstructed images is proposed. Phase-shifting errors are introduced in phase-shifted holograms for numerous reasons, such as the non-linearity of piezoelectric transducers (PZTs, wavelength fluctuations in lasers, and environmental disturbances, leading to poor-quality reconstructions. In our system, in addition to the camera used to record object information, an extra camera is used to record interferograms, which are used to analyze phase-shifting errors using a sampling Moiré technique. The quality of the reconstructed object images can be improved by the phase-shifting error compensation algorithm. Both the numerical simulation and experiment demonstrate the effectiveness of the proposed system.

  4. Optimal wavelength band clustering for multispectral iris recognition.

    Science.gov (United States)

    Gong, Yazhuo; Zhang, David; Shi, Pengfei; Yan, Jingqi

    2012-07-01

    This work explores the possibility of clustering spectral wavelengths based on the maximum dissimilarity of iris textures. The eventual goal is to determine how many bands of spectral wavelengths will be enough for iris multispectral fusion and to find these bands that will provide higher performance of iris multispectral recognition. A multispectral acquisition system was first designed for imaging the iris at narrow spectral bands in the range of 420 to 940 nm. Next, a set of 60 human iris images that correspond to the right and left eyes of 30 different subjects were acquired for an analysis. Finally, we determined that 3 clusters were enough to represent the 10 feature bands of spectral wavelengths using the agglomerative clustering based on two-dimensional principal component analysis. The experimental results suggest (1) the number, center, and composition of clusters of spectral wavelengths and (2) the higher performance of iris multispectral recognition based on a three wavelengths-bands fusion.

  5. Calibration-free wavelength-modulation spectroscopy based on a swiftly determined wavelength-modulation frequency response function of a DFB laser.

    Science.gov (United States)

    Zhao, Gang; Tan, Wei; Hou, Jiajia; Qiu, Xiaodong; Ma, Weiguang; Li, Zhixin; Dong, Lei; Zhang, Lei; Yin, Wangbao; Xiao, Liantuan; Axner, Ove; Jia, Suotang

    2016-01-25

    A methodology for calibration-free wavelength modulation spectroscopy (CF-WMS) that is based upon an extensive empirical description of the wavelength-modulation frequency response (WMFR) of DFB laser is presented. An assessment of the WMFR of a DFB laser by the use of an etalon confirms that it consists of two parts: a 1st harmonic component with an amplitude that is linear with the sweep and a nonlinear 2nd harmonic component with a constant amplitude. Simulations show that, among the various factors that affect the line shape of a background-subtracted peak-normalized 2f signal, such as concentration, phase shifts between intensity modulation and frequency modulation, and WMFR, only the last factor has a decisive impact. Based on this and to avoid the impractical use of an etalon, a novel method to pre-determine the parameters of the WMFR by fitting to a background-subtracted peak-normalized 2f signal has been developed. The accuracy of the new scheme to determine the WMFR is demonstrated and compared with that of conventional methods in CF-WMS by detection of trace acetylene. The results show that the new method provides a four times smaller fitting error than the conventional methods and retrieves concentration more accurately.

  6. Application of holographic sub-wavelength diffraction gratings for monitoring of kinetics of bioprocesses

    Energy Technology Data Exchange (ETDEWEB)

    Tamulevicius, Tomas, E-mail: tomas.tamulevicius@ktu.lt [Institute of Materials Science of Kaunas University of Technology, Savanoriu Ave. 271, LT-50131, Kaunas (Lithuania); Seperys, Rimas; Andrulevicius, Mindaugas; Kopustinskas, Vitoldas; Meskinis, Sarunas; Tamulevicius, Sigitas [Institute of Materials Science of Kaunas University of Technology, Savanoriu Ave. 271, LT-50131, Kaunas (Lithuania); Mikalayeva, Valeryia; Daugelavicius, Rimantas [Department of Biochemistry and Biotechnologies of Vytautas Magnus University, Vileikos St. 8, LT-44404 Kaunas (Lithuania)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Refractive index sensor based on DLC holographic sub-wavelength period grating. Black-Right-Pointing-Pointer Spectroscopic analysis of polarized white light reflected from the grating. Black-Right-Pointing-Pointer Control of critical wavelength shift and reflectivity changes. Black-Right-Pointing-Pointer Testing of model liquid analyte materials. Black-Right-Pointing-Pointer Evaluation of interaction between B. subtilis cells and lysozyme. - Abstract: In this work we present a refractive index (RI) sensor based on a sub-wavelength holographic diffraction grating. The sensor chip was fabricated by dry etching of the finely spaced (d = 428 nm) diffraction grating in SiO{sub x} doped diamond like carbon (DLC) film. It is shown that employing a fabricated sensor chip, and using the proposed method of analysis of data, one can inspect kinetics of processes in liquids occurring in the vicinity of the grating surface. The method is based on the spectral composition analysis of polarized polychromatic light reflected from the sub-wavelength diffraction grating. The RI measurement system was tested with different model liquid analytes including 25 wt.%, 50 wt.% sugar water solutions, 10 Degree-Sign C, 50 Degree-Sign C distilled water, also Gram-positive bacteria Bacillus subtilis interaction with ion-permeable channels forming antibiotic gramicidin D and a murolytic enzyme lysozyme. Analysis of the data set of specular reflection spectra enabled us to follow the kinetics of the RI changes in the analyte with millisecond resolution. Detectable changes in the effective RI were not worse than {Delta}n = 10{sup -4}.

  7. Wavelength dependent loading of traps in the persistent phosphor SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Hagemann, H.; Lovy, D. [Department of Physical Chemistry, University of Geneva, Quai E. Ansermet 30, CH-1211 Geneva 4 (Switzerland); Yoon, S.; Pokrant, S. [Laboratory Materials for Energy Conversion, Empa-Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600, Dübendorf (Switzerland); Gartmann, N.; Walfort, B. [LumiNova AG, Speicherstrasse 60a, CH-9053, Teufen (Switzerland); Bierwagen, J., E-mail: Jakob.Bierwagen@unige.ch [Department of Physical Chemistry, University of Geneva, Quai E. Ansermet 30, CH-1211 Geneva 4 (Switzerland)

    2016-02-15

    The persistent phosphorescence and thermoluminescence of SrAl{sub 2}O{sub 4}:Eu{sup 2+}:Dy{sup 3+} is reported for a variety of different excitation wavelengths and excitation temperatures, to provide new insights in the mechanism of the trapping and detrapping. These measurements reveal that the trapping is strongly dependent on the wavelength and temperature. First, with increasing loading temperature, the thermoluminescence peak shifts to lower temperatures which corresponds to a change of trap population. Secondly, the integrated thermoluminescent intensity increases with increasing loading temperature. All wavelength and temperature dependent experiments indicate that the loading of the traps is a thermally activated processes. Utilizing different wavelengths for loading, this effect can be enhanced or reduced. Furthermore excitation with UV-B-light reveals a tendency for detrapping the phosphor, reducing the resulting thermoluminescent intensity and changing the population of the traps.

  8. Acute effects of different light spectra on simulated night-shift work without circadian alignment.

    Science.gov (United States)

    Canazei, Markus; Pohl, Wilfried; Bliem, Harald R; Weiss, Elisabeth M

    2017-01-01

    Short-wavelength and short-wavelength-enhanced light have a strong impact on night-time working performance, subjective feelings of alertness and circadian physiology. In the present study, we investigated acute effects of white light sources with varied reduced portions of short wavelengths on cognitive and visual performance, mood and cardiac output.Thirty-one healthy subjects were investigated in a balanced cross-over design under three light spectra in a simulated night-shift paradigm without circadian adaptation.Exposure to the light spectrum with the largest attenuation of short wavelengths reduced heart rate and increased vagal cardiac parameters during the night compared to the other two light spectra without deleterious effects on sustained attention, working memory and subjective alertness. In addition, colour discrimination capability was significantly decreased under this light source.To our knowledge, the present study for the first time demonstrates that polychromatic white light with reduced short wavelengths, fulfilling current lighting standards for indoor illumination, may have a positive impact on cardiac physiology of night-shift workers without detrimental consequences for cognitive performance and alertness.

  9. Shifting schedules: the health effects of reorganizing shift work.

    Science.gov (United States)

    Bambra, Clare L; Whitehead, Margaret M; Sowden, Amanda J; Akers, Joanne; Petticrew, Mark P

    2008-05-01

    Approximately one fifth of workers are engaged in some kind of shift work. The harmful effects of shift work on the health and work-life balance of employees are well known. A range of organizational interventions has been suggested to address these negative effects. This study undertook the systematic review (following Quality Of Reporting Of Meta [QUORUM] analyses guidelines) of experimental and quasi-experimental studies, from any country (in any language) that evaluated the effects on health and work-life balance of organizational-level interventions that redesign shift work schedules. Twenty-seven electronic databases (medical, social science, economic) were searched. Data extraction and quality appraisal were carried out by two independent reviewers. Narrative synthesis was performed. The review was conducted between October 2005 and November 2006. Twenty-six studies were found relating to a variety of organizational interventions. No one type of intervention was found to be consistently harmful to workers. However, three types were found to have beneficial effects on health and work-life balance: (1) switching from slow to fast rotation, (2) changing from backward to forward rotation, and (3) self-scheduling of shifts. Improvements were usually at little or no direct organizational cost. However, there were concerns about the generalizability of the evidence, and no studies reported on impacts on health inequalities. This review reinforces the findings of epidemiologic and laboratory-based research by suggesting that certain organizational-level interventions can improve the health of shift workers, their work-life balance, or both. This evidence could be useful when designing interventions to improve the experience of shift work.

  10. SAT in shift manager training

    International Nuclear Information System (INIS)

    Lecuyer, F.

    1995-01-01

    EDF has improved the organization of the operation shift teams with the replacement of shift supervisor in shift manager function. The shift manager is not only responsible for tasks associated to plant operation (production), but he is also responsible for safety of these tasks and for management of shift team members. A job analysis of this new job position has been performed in order to design the training programme. It resulted in a 10-month training programme that includes 8 weeks in safety-related topics and 12 weeks in soft-skills related topics. The safety related training courses are mandatory, the other courses are optional courses depending on individual trainee needs. The training also includes the development of management competencies. During the 10 month period, each trainee develops an individual project that is evaluated by NPP manager. As well, as group project is undertaken by the trainees and overseen by a steering committee. The steering committee participates in the evaluation process and provides operational experience feedback to the trainee groups and to the overall programme

  11. Single Mode Fiber Optic Transceiver Using Short Wavelength Active Devices In Long Wavelength Fiber

    Science.gov (United States)

    Gillham, Frederick J.; Campbell, Daniel R.; Corke, Michael; Stowe, David W.

    1990-01-01

    Presently, single mode optical fiber technology is being utilized in systems to supply telephone service to the subscriber. However, in an attempt to be competitive with copper based systems, there are many development programs underway to determine the most cost effective solution while still providing a service that will either satisfy or be upgradeable to satisfy the demands of the consumer for the next 10 to 20 years. One such approach is to combine low cost laser transmitters and silicon receivers, which have been developed for the "compact disc" industry, with fiber that operates in the single mode regime at 1300 nm. In this paper, an optical transceiver will be presented, consisting of a compact disc laser, a silicon detector and a single mode coupler at 1300 nm. A possible system layout is presented which operates at 780 nm bi-directionally for POTS and upgradeable to 1300 nm for video services. There are several important design criteria that have to be considered in the development of such a system which will be addressed. These include: 1. Optimization of coupled power from laser to fiber while maintaining stable launched conditions over a wide range of environmental conditions. 2. Consideration of the multimode operation of the 1300 nm single mode fiber while operating in the 780 nm wavelength region. 3. Development of a low cost pseudo-wavelength division multiplexer for 1300 nm single mode/780 nm multimode operation and a low cost dual mode 50/50, 780 nm splitter using 1300 nm fiber. Details will be given of the design criteria and solution in terms of optimized design. Results of the performance of several prototype devices will be given with indications of the merits of this approach and where further development effort should be applied.

  12. Does the ARFIMA really shift?

    DEFF Research Database (Denmark)

    Monache, Davide Delle; Grassi, Stefano; Santucci de Magistris, Paolo

    Short memory models contaminated by level shifts have long-memory features similar to those associated to processes generated under fractional integration. In this paper, we propose a robust testing procedure, based on an encompassing parametric specification, that allows to disentangle the level...... the highest power compared to other existing tests for spurious long-memory. Finally, we illustrate the usefulness of the proposed approach on the daily series of bipower variation and share turnover and on the monthly inflation series of G7 countries....... shift term from the ARFIMA component. The estimation is carried out via a state-space methodology and it leads to a robust estimate of the fractional integration parameter also in presence of level shifts.The Monte Carlo simulations show that this approach produces unbiased estimates of the fractional...

  13. Free-space wavelength-multiplexed optical scanner.

    Science.gov (United States)

    Yaqoob, Z; Rizvi, A A; Riza, N A

    2001-12-10

    A wavelength-multiplexed optical scanning scheme is proposed for deflecting a free-space optical beam by selection of the wavelength of the light incident on a wavelength-dispersive optical element. With fast tunable lasers or optical filters, this scanner features microsecond domain scan setting speeds and large- diameter apertures of several centimeters or more for subdegree angular scans. Analysis performed indicates an optimum scan range for a given diffraction order and grating period. Limitations include beam-spreading effects based on the varying scanner aperture sizes and the instantaneous information bandwidth of the data-carrying laser beam.

  14. Rational choices for the wavelengths of a two color interferometer

    International Nuclear Information System (INIS)

    Jobes, F.C.

    1995-07-01

    If in a two color interferometer for plasma density measurements, the two wavelengths are chosen to have a ratio that is a rational number, and if the signals from each of the wavelengths are multiplied in frequency by the appropriate integer of the rational number and then heterodyned together, the resultant signal will have all effects of component motion nulled out. A phase measurement of this signal will have only plasma density information in it. With CO 2 lasers, it is possible to find suitable wavelength pairs which are close enough to rational numbers to produce an improvement of about 100 in density resolution, compared to standard two color interferometers

  15. Radiative flux calculations at UV and visible wavelengths

    International Nuclear Information System (INIS)

    Grossman, A.S.; Grant, K.E.; Wuebbles, D.J.

    1993-10-01

    A radiative transfer model to calculate the short wavelength fluxes at altitudes between 0 and 80 km has been developed at LLNL. The wavelength range extends from 175--735 nm. This spectral range covers the UV-B wavelength region, 250--350 nm, with sufficient resolution to allow comparison of UV-B measurements with theoretical predictions. Validation studies for the model have been made for both UV-B ground radiation calculations and tropospheric solar radiative forcing calculations for various ozone distributions. These studies indicate that the model produces results which agree well with respect to existing UV calculations from other published models

  16. Estimates of SASE power in the short wavelength region

    International Nuclear Information System (INIS)

    Kim, Kwang-Je.

    1992-03-01

    Given a sufficiently bright electron beam, the self-amplified-spontaneous emission (SASE) can provide gigawatts of short wavelength coherent radiation. The advantages of SASE approach are that is requires neither optical cavity nor an imput seed laser. In this note, we estimate the peak power performance of SASE for wavelengths shorter than 1000 Angstrom. At each wavelength, we calculate the saturated power from a uniform parameter undulator and the enhanced power from a tapered undulator. The method described here is an adaptation of that discussed by L.H. Yu, who discussed the harmonic generation scheme with seeded laser, to the case of SASE

  17. Infrared speckle observations of the binary Ross 614 AB - combined shift-and-add and zero-and-add analysis

    International Nuclear Information System (INIS)

    Davey, B.L.K.; Bates, R.H.T.; Cocke, W.J.; Mccarthy, D.W. Jr.; Christou, J.C.

    1989-01-01

    One-dimensional infrared speckle scans of Ross 614 AB were recorded at a wavelength of 2.2 microns, and the three bins corresponding to the three best seeing conditions were further processed by applying a shift-and-add algorithm to the set of images contained within each bin, generating three shift-and-add images with differing shift-and-add point-spread functions. A zero-and-add technique was used to deconvolve the three shift-and-add images in order to obtain parameters corresponding to the separation and the brightness ratio of a two-component model of Ross 614 Ab. Least-squares analysis results reveal a separation of 1.04 arcsec and a brightness ratio of 4.3 for the binary system at this wavelength. 31 refs

  18. Paradigm Shifts in Ophthalmic Diagnostics.

    Science.gov (United States)

    Sebag, J; Sadun, Alfredo A; Pierce, Eric A

    2016-08-01

    Future advances in ophthalmology will see a paradigm shift in diagnostics from a focus on dysfunction and disease to better measures of psychophysical function and health. Practical methods to define genotypes will be increasingly important and non-invasive nanotechnologies are needed to detect molecular changes that predate histopathology. This is not a review nor meant to be comprehensive. Specific topics have been selected to illustrate the principles of important paradigm shifts that will influence the future of ophthalmic diagnostics. It is our impression that future evaluation of vision will go beyond visual acuity to assess ocular health in terms of psychophysical function. The definition of disease will incorporate genotype into what has historically been a phenotype-centric discipline. Non-invasive nanotechnologies will enable a paradigm shift from disease detection on a cellular level to a sub-cellular molecular level. Vision can be evaluated beyond visual acuity by measuring contrast sensitivity, color vision, and macular function, as these provide better insights into the impact of aging and disease. Distortions can be quantified and the psychophysical basis of vision can be better evaluated than in the past by designing tests that assess particular macular cell function(s). Advances in our understanding of the genetic basis of eye diseases will enable better characterization of ocular health and disease. Non-invasive nanotechnologies can assess molecular changes in the lens, vitreous, and macula that predate visible pathology. Oxygen metabolism and circulatory physiology are measurable indices of ocular health that can detect variations of physiology and early disease. This overview of paradigm shifts in ophthalmology suggests that the future will see significant improvements in ophthalmic diagnostics. The selected topics illustrate the principles of these paradigm shifts and should serve as a guide to further research and development. Indeed

  19. Progressive Red Shifts in the Late-Time Spectra of Type Ia Supernovae

    Science.gov (United States)

    Black, Christine; Fesen, Robert; Parrent, Jerod

    2017-01-01

    We examine the evolution of late-time, optical nebular features of Type Ia supernovae (SNe Ia) using a sample consisting of 160 spectra of 27 normal SNe Ia taken from the literature as well as unpublished spectra of SN 2008Q and ASASSN-14lp. Particular attention is given to nebular features between 4000-6000 Ang in terms of temporal changes in width and central wavelength. Analysis of the prominent late-time 4700 Ang feature shows a progressive central wavelength shift from ˜4600 Ang to longer wavelengths out to at least day +300 for our entire sample. We find no evidence for the feature’s red-ward shift slowing or halting at an [Fe III] blend centroid ˜4700 Ang as has been proposed. Two weaker adjacent features at around 4850 and 5000 Ang exhibit similar red shifts to that of the 4700 Ang feature. We conclude that the ubiquitous red shift of these common late-time SN Ia spectral features is not mainly due to a decrease in line velocities of forbidden Fe emissions, but the result of decreasing line velocities and opacity of permitted Fe absorption lines.

  20. Morphisms Between Sofic Shift Spaces

    DEFF Research Database (Denmark)

    Nielsen, Jan Agentoft

    The lower entropy factor problem asks for necessary and sufficient conditions for the existence of a factor map from a (mixing) sofic shift space onto another (mixing) sofic subshift of lower entropy. The problem was posed by Mike Boyle in 1984. It remains an open problem, but the present thesis...... gives a re-formulation which can be used to effectively decide the question for a larger class of sofic shifts than all previous results. In addition, the methods are used to make progress on the corresponding embedding problem which asks for necessary and sufficient conditions for the existence...

  1. Shift-Variant Multidimensional Systems.

    Science.gov (United States)

    1985-05-29

    x,y;u,v) is the system response at (x,y) to an unit impulse applied at (u,v). The presence of additive noise in the preceding input-output model of a...space model developed works very effi- ciently to deblur images affected by 2-D linear shift- varying blurs, its use, in presence of noise needs to be...causal linear shift-variant (LSV) system, whose impulse res- ponse is a K-th order degenerate sequence, a K-th order state-space model was obtained

  2. Explaining (Missing) Regulator Paradigm Shifts

    DEFF Research Database (Denmark)

    Wigger, Angela; Buch-Hansen, Hubert

    2014-01-01

    The global financial and economic crisis has prompted some scholars to suggest that a fundamental regulatory shift away from neoliberalism will take place – both in general and in the field of EU competition regulation. This paper shows that so far no radical break with the neoliberal type...... regulation after the crisis in the 1970s, the paper argues that the preconditions for a fundamental shift in this issue area are not present this time around. Several reasons account for this: the current crisis has been construed by economic and political elites as a crisis within and not of neoliberal...

  3. Carbon dioxide on the satellites of Saturn: Results from the Cassini VIMS investigation and revisions to the VIMS wavelength scale

    Science.gov (United States)

    Cruikshank, D.P.; Meyer, A.W.; Brown, R.H.; Clark, R.N.; Jaumann, R.; Stephan, K.; Hibbitts, C.A.; Sandford, S.A.; Mastrapa, R.M.E.; Filacchione, G.; Ore, C.M.D.; Nicholson, P.D.; Buratti, B.J.; McCord, T.B.; Nelson, R.M.; Dalton, J.B.; Baines, K.H.; Matson, D.L.

    2010-01-01

    Several of the icy satellites of Saturn show the spectroscopic signature of the asymmetric stretching mode of C-O in carbon dioxide (CO2) at or near the nominal solid-phase laboratory wavelength of 4.2675 ??m (2343.3 cm-1), discovered with the Visible-Infrared Mapping Spectrometer (VIMS) on the Cassini spacecraft. We report here on an analysis of the variation in wavelength and width of the CO2 absorption band in the spectra of Phoebe, Iapetus, Hyperion, and Dione. Comparisons are made to laboratory spectra of pure CO2, CO2 clathrates, ternary mixtures of CO2 with other volatiles, implanted and adsorbed CO2 in non-volatile materials, and ab initio theoretical calculations of CO2 * nH2O. At the wavelength resolution of VIMS, the CO2 on Phoebe is indistinguishable from pure CO2 ice (each molecule's nearby neighbors are also CO2) or type II clathrate of CO2 in H2O. In contrast, the CO2 band on Iapetus, Hyperion, and Dione is shifted to shorter wavelengths (typically ???4.255 ??m (???2350.2 cm-1)) and broadened. These wavelengths are characteristic of complexes of CO2 with different near-neighbor molecules that are encountered in other volatile mixtures such as with H2O and CH3OH, and non-volatile host materials like silicates, some clays, and zeolites. We suggest that Phoebe's CO2 is native to the body as part of the initial inventory of condensates and now exposed on the surface, while CO2 on the other three satellites results at least in part from particle or UV irradiation of native H2O plus a source of C, implantation or accretion from external sources, or redistribution of native CO2 from the interior. The analysis presented here depends on an accurate VIMS wavelength scale. In preparation for this work, the baseline wavelength calibration for the Cassini VIMS was found to be distorted around 4.3 ??m, apparently as a consequence of telluric CO2 gas absorption in the pre-launch calibration. The effect can be reproduced by convolving a sequence of model detector

  4. WAVELENGTH ACCURACY OF THE KECK HIRES SPECTROGRAPH AND MEASURING CHANGES IN THE FINE STRUCTURE CONSTANT

    International Nuclear Information System (INIS)

    Griest, Kim; Whitmore, Jonathan B.; Wolfe, Arthur M.; Prochaska, J. Xavier; Howk, J. Christopher; Marcy, Geoffrey W.

    2010-01-01

    We report on an attempt to accurately wavelength calibrate four nights of data taken with the Keck HIRES spectrograph on QSO PHL957, for the purpose of determining whether the fine structure constant was different in the past. Using new software and techniques, we measured the redshifts of various Ni II, Fe II, Si II, etc. lines in a damped Lyα system at z = 2.309. Roughly half the data were taken through the Keck iodine cell which contains thousands of well calibrated iodine lines. Using these iodine exposures to calibrate the normal Th-Ar Keck data pipeline output, we found absolute wavelength offsets of 500 m s -1 to 1000 m s -1 with drifts of more than 500 m s -1 over a single night, and drifts of nearly 2000 m s -1 over several nights. These offsets correspond to an absolute redshift of uncertainty of about Δz ∼ 10 -5 (Δλ ∼ 0.02 A), with daily drifts of around Δz ∼ 5 x 10 -6 (Δλ ∼ 0.01 A), and multiday drifts of nearly Δz ∼ 2 x 10 -5 (∼0.04 A). The causes of the wavelength offsets are not known, but since claimed shifts in the fine structure constant would result in velocity shifts of less than 100 m s -1 , this level of systematic uncertainty may make it difficult to use Keck HIRES data to constrain the change in the fine structure constant. Using our calibrated data, we applied both our own fitting software and standard fitting software to measure Δα/α, but discovered that we could obtain results ranging from significant detection of either sign, to strong null limits, depending upon which sets of lines and which fitting method were used. We thus speculate that the discrepant results on Δα/α reported in the literature may be due to random fluctuations coming from underestimated systematic errors in wavelength calibration and fitting procedure.

  5. Effect of wavelength shifters on water Cherenkov detectors

    Energy Technology Data Exchange (ETDEWEB)

    Badino, G; Galeotti, P; Periale, L; Saavedra, O; Turtelli, A [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Turin Univ. (Italy). Ist. di Fisica Generale)

    1981-06-15

    We report the results of a test showing that concentrations of approx. equal to 2 mg/l of wavelength shifter in water give almost the maximum efficiency of detection without losing the directionality of Cherenkov light.

  6. Multi-wavelength Ocean Profiling and Atmospheric Lidar

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to build and demonstrate the world's first multi-wavelength ocean-profiling high spectral resolution lidar (HSRL). The lidar will provide profiles of...

  7. Isoplanatic patch of the human eye for arbitrary wavelengths

    Science.gov (United States)

    Han, Guoqing; Cao, Zhaoliang; Mu, Quanquan; Wang, Yukun; Li, Dayu; Wang, Shaoxin; Xu, Zihao; Wu, Daosheng; Hu, Lifa; Xuan, Li

    2018-03-01

    The isoplanatic patch of the human eye is a key parameter for the adaptive optics system (AOS) designed for retinal imaging. The field of view (FOV) usually sets to the same size as the isoplanatic patch to obtain high resolution images. However, it has only been measured at a specific wavelength. Here we investigate the wavelength dependence of this important parameter. An optical setup is initially designed and established in a laboratory to measure the isoplanatic patch at various wavelengths (655 nm, 730 nm and 808 nm). We established the Navarro wide-angle eye model in Zemax software to further validate our results, which suggested high consistency between the two. The isoplanatic patch as a function of wavelength was obtained within the range of visible to near-infrared, which can be expressed as: θ=0.0028 λ - 0 . 74. This work is beneficial for the AOS design for retinal imaging.

  8. Portable Long-Wavelength Infrared Camera for Civilian Application

    Science.gov (United States)

    Gunapala, S. D.; Krabach, T. N.; Bandara, S. V.; Liu, J. K.

    1997-01-01

    In this paper, we discuss the performance of this portable long-wavelength infrared camera in quantum efficiency, NEAT, minimum resolvable temperature differnce (MRTD), uniformity, etc. and its application in science, medicine and defense.

  9. Infrared presensitization photography at deuterium fluoride laser wavelengths

    International Nuclear Information System (INIS)

    Geary, J.M.; Ross, K.; Suter, K.

    1989-01-01

    Near-field irradiance distributions of a deuterium flouride laser system are obtained using infrared presensitization photography. This represents the shortest wavelength region to employ this technique thus far

  10. Leadership Shifts in Changing Field

    Science.gov (United States)

    Zubrzycki, Jaclyn

    2013-01-01

    As groups representing local and state education players struggle to remain relevant in a policy conversation often dominated by foundations, think tanks, new advocacy groups, and political and business figures, a shift in leadership has been under way at major associations. Most of the changes have come as part of the natural churn; former…

  11. Crichton's phase-shift ambiguity

    NARCIS (Netherlands)

    Atkinson, D.; Johnson, P.W.; Mehta, N.; Roo, M. de

    1973-01-01

    A re-examination of the SPD phase-shift ambiguity is made with a view to understanding certain singular features of the elastic unitarity constraint. An explicit solution of Crichton's equations is presented, and certain features of this solution are displayed graphically. In particular, it is shown

  12. Environmental Protection: a shifting focus

    NARCIS (Netherlands)

    Dr. ir. Jan Venselaar

    2004-01-01

    The last two decades have seen a fundamental change in the way chemistry handles environmental issues. A shift in focus has occurred from 'end-of-pipe' to prevention and process integration. Presently an even more fundamental change is brought about by the need for sustainable development. It is

  13. Anthropometric changes and fluid shifts

    Science.gov (United States)

    Thornton, W. E.; Hoffler, G. W.; Rummel, J. A.

    1974-01-01

    Several observations of body size, shape, posture, and configuration were made to document changes resulting from direct effects of weightlessness during the Skylab 4 mission. After the crewmen were placed in orbit, a number of anatomical and anthropometric changes occurred including a straightening of the thoracolumbar spine, a general decrease in truncal girth, and an increase in height. By the time of the earliest in-flight measurement on mission day 3, all crewmen had lost more than two liters of extravascular fluid from the calf and thigh. The puffy facies, the bird legs effect, the engorgement of upper body veins, and the reduced volume of lower body veins were all documented with photographs. Center-of-mass measurements confirmed a fluid shift cephalad. This shift remained throughout the mission until recovery, when a sharp reversal occurred; a major portion of the reversal was completed in a few hours. The anatomical changes are of considerable scientific interest and of import to the human factors design engineer, but the shifts of blood and extravascular fluid are of more consequence. It is hypothesized that the driving force for the fluid shift is the intrinsic and unopposed lower limb elasticity that forces venous blood and then other fluid cephalad.

  14. Self-amplified spontaneous emission for short wavelength coherent radiation

    International Nuclear Information System (INIS)

    Kim, K.J.; Xie, M.

    1992-09-01

    We review the recent progress in our understanding of the self-amplified spontaneous emission (SASE), emphasizing the application to short wavelength generation. Simple formulae are given for the start-up, exponential gain and the saturation of SASE. Accelerator technologies producing high brightness electron beams required for short wavelength SASE are discussed. An example utilizing electron beams from a photocathode-linac system to produce 4nm SASE in the multigigawatt range is presented

  15. Valuing spectrum at mm wavelengths for cellular networks

    OpenAIRE

    Shaw, B. A.; Beltrán, H. F.; Sowerby, K. W.

    2017-01-01

    This paper investigates the economic value of spectrum at mm wavelengths. The analysis uses four techniques to value spectrum, namely a benchmarking comparison, a discounted cash flow analysis, a real options approach and a deprival method. The methods to calculate spectrum value presented in this paper can be used for any spectrum band and in any country. However, to determine the value of mm wavelengths for cellular networks, we have used data from New Zealand, specifically for the existing...

  16. Long wavelength scintillators for fiber-optic applications

    International Nuclear Information System (INIS)

    Lyons, P.B.; Franks, L.; Lutz, S.; Flournoy, J.; Fullman, E.

    1980-01-01

    The use of fiber optics in plasma diagnostics has spurred the development of long wavelength scintillators with fast temporal characteristics. In this paper we describe several new liquid scintillator systems with fluorescent emissions maxima up to 730 nm. Subnanosecond scintillator FWHM response times have been obtained by the operation of liquid scintillators at elevated temperatures. Data on fiber system sensitivity versus fiber length and scintillator emission wavelength will be presented

  17. Optical cross-connect circuit using hitless wavelength selective switch.

    Science.gov (United States)

    Goebuchi, Yuta; Hisada, Masahiko; Kato, Tomoyuki; Kokubun, Yasuo

    2008-01-21

    We have proposed and demonstrated the basic elements of a full matrix optical switching circuit (cross-connect circuit) using a hitless wavelength selective switch (WSS). The cross-connect circuits are made of a multi-wavelength channel selective switch consisting of cascaded hitless WSSs, and a multi-port switch. These switching elements are realized through the individual Thermo-Optic (TO) tuning of a series-coupled microring resonator, and can switch arbitrary wavelength channels without blocking other wavelength channels during tuning. We demonstrate a four wavelength selective switch using a parallel topology of double series coupled microring resonators and a three wavelength selective switch using a parallel topology of quadruple series coupled microring resonators. Since the spectrum shape of quadruple series coupled microring is much more box-like than the double series, a high extinction ratio of 39.0-46.6 dB and low switching cross talk of 19.3-24.5 dB were achieved.

  18. Impact of beacon wavelength on phase-compensation performance

    Science.gov (United States)

    Enterline, Allison A.; Spencer, Mark F.; Burrell, Derek J.; Brennan, Terry J.

    2017-09-01

    This study evaluates the effects of beacon-wavelength mismatch on phase-compensation performance. In general, beacon-wavelength mismatch occurs at the system level because the beacon-illuminator laser (BIL) and high-energy laser (HEL) are often at different wavelengths. Such is the case, for example, when using an aperture sharing element to isolate the beam-control sensor suite from the blinding nature of the HEL. With that said, this study uses the WavePlex Toolbox in MATLAB® to model ideal spherical wave propagation through various atmospheric-turbulence conditions. To quantify phase-compensation performance, we also model a nominal adaptive-optics (AO) system. We achieve correction from a Shack-Hartmann wavefront sensor and continuous-face-sheet deformable mirror using a least-squares phase reconstruction algorithm in the Fried geometry and a leaky integrator control law. To this end, we plot the power in the bucket metric as a function of BIL-HEL wavelength difference. Our initial results show that positive BIL-HEL wavelength differences achieve better phase compensation performance compared to negative BIL-HEL wavelength differences (i.e., red BILs outperform blue BILs). This outcome is consistent with past results.

  19. Wavelength calibration of an imaging spectrometer based on Savart interferometer

    Science.gov (United States)

    Li, Qiwei; Zhang, Chunmin; Yan, Tingyu; Quan, Naicheng; Wei, Yutong; Tong, Cuncun

    2017-09-01

    The basic principle of Fourier-transform imaging spectrometer (FTIS) based on Savart interferometer is outlined. The un-identical distribution of the optical path difference which leads to the wavelength drift of each row of the interferogram is analyzed. Two typical methods for wavelength calibration of the presented system are described. The first method unifies different spectral intervals and maximum spectral frequencies of each row by a reference monochromatic light with known wavelength, and the dispersion compensation of Savart interferometer is also involved. The second approach is based on the least square fitting which builds the functional relation between recovered wavelength, row number and calibrated wavelength by concise equations. The effectiveness of the two methods is experimentally demonstrated with monochromatic lights and mixed light source across the detecting band of the system, and the results indicate that the first method has higher precision and the mean root-mean-square error of the recovered wavelengths is significantly reduced from 19.896 nm to 1.353 nm, while the second method is more convenient to implement and also has good precision of 2.709 nm.

  20. Study of a Digital SiPM for TOF-PET

    CERN Document Server

    Heller, M

    2013-01-01

    The digital Silicon Photomultipliers (dSiPM) from Philips have been used in a study aiming at the proof of principle of an axial positron emission tomography detector with time of flight capabilities. These novel detectors provide various features not present in analog devices. The readout chain is programmable and offers various options affecting the functioning of the device. For each application a characterization and an optimization of the settings must be done in order to get the best out of the sensor. The axial geometry already developed for the AX-PET demonstrator implies the readout of LYSO crystals (used for energy measurement and transaxial coordinate) and of wavelength shifting (WLS) strips (axial coordinate). The readout of these two types of scintillators requires dedicated operation modes of the dSiPM. This technical note describes the characterization of the sensors with the goal of an optimized performance for LYSO crystals and WLS strips.

  1. The optical instrumentation of the ATLAS Tile Calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Abdallah, J [IFIC, Centro Mixto Universidad de Valencia-CSIC, E46100 Burjassot, Valencia (Spain); Adragna, P; Bosi, F [Pisa University and INFN, Pisa (Italy); Alexa, C; Boldea, V [National Institute of Physics and Nuclear Engineering, Bucharest (Romania); Alves, R [LIP and FCTUC Univ. of Coimbra (Portugal); Amaral, P; Andresen, X [CERN, Geneva (Switzerland); Ananiev, A [LIP and IDMEC-IST, Lisbon (Portugal); Anderson, K [University of Chicago, Chicago, Illinois 60637 (United States); Antonaki, A [University of Athens, Athens (Greece); Batusov, V [JINR, Dubna (Russian Federation); Bednar, P [Comenius University, Bratislava (Slovakia); Bergeaas, E; Bohm, C [Stockholm University, Stockholm (Sweden); Biscarat, C [LPC Clermont-Ferrand, Universite Blaise Pascal / CNRS-IN2P3, Clermont-Ferrand (France); Blanch, O; Blanchot, G; Bosman, M [Institut de Fisica d' Altes Energies, Universitat Autonoma de Barcelona, Barcelona (Spain); Bromberg, C [Michigan State University, East Lansing, Michigan 48824 (United States); others, and

    2013-01-15

    The Tile Calorimeter, covering the central region of the ATLAS experiment up to pseudorapidities of {+-}1.7, is a sampling device built with scintillating tiles that alternate with iron plates. The light is collected in wave-length shifting (WLS) fibers and is read out with photomultipliers. In the characteristic geometry of this calorimeter the tiles lie in planes perpendicular to the beams, resulting in a very simple and modular mechanical and optical layout. This paper focuses on the procedures applied in the optical instrumentation of the calorimeter, which involved the assembly of about 460,000 scintillator tiles and 550,000 WLS fibers. The outcome is a hadronic calorimeter that meets the ATLAS performance requirements, as shown in this paper.

  2. The optical instrumentation of the ATLAS Tile Calorimeter

    International Nuclear Information System (INIS)

    Abdallah, J; Adragna, P; Bosi, F; Alexa, C; Boldea, V; Alves, R; Amaral, P; Andresen, X; Ananiev, A; Anderson, K; Antonaki, A; Batusov, V; Bednar, P; Bergeaas, E; Bohm, C; Biscarat, C; Blanch, O; Blanchot, G; Bosman, M; Bromberg, C

    2013-01-01

    The Tile Calorimeter, covering the central region of the ATLAS experiment up to pseudorapidities of ±1.7, is a sampling device built with scintillating tiles that alternate with iron plates. The light is collected in wave-length shifting (WLS) fibers and is read out with photomultipliers. In the characteristic geometry of this calorimeter the tiles lie in planes perpendicular to the beams, resulting in a very simple and modular mechanical and optical layout. This paper focuses on the procedures applied in the optical instrumentation of the calorimeter, which involved the assembly of about 460,000 scintillator tiles and 550,000 WLS fibers. The outcome is a hadronic calorimeter that meets the ATLAS performance requirements, as shown in this paper.

  3. Solitonic supercontinuum of femtosecond mid-IR pulses in W-type index tellurite fibers with two zero dispersion wavelengths

    Directory of Open Access Journals (Sweden)

    S. Kedenburg

    2016-11-01

    Full Text Available We present a detailed experimental parameter study on mid-IR supercontinuum generation in W-type index tellurite fibers, which reveals how the core diameter, pump wavelength, fiber length, and pump power dramatically influence the spectral broadening. As pump source, we use femtosecond mid-IR pulses from a post-amplified optical parametric oscillator tunable between 1.7 μm and 4.1 μm at 43 MHz repetition rate. We are able to generate red-shifted dispersive waves up to a wavelength of 5.1 μm by pumping a tellurite fiber in the anomalous dispersion regime between its two zero dispersion wavelengths. Distinctive soliton dynamics can be identified as the main broadening mechanism resulting in a maximum spectral width of over 2000 nm with output powers of up to 160 mW. We experimentally demonstrated that efficient spectral broadening with considerably improved power proportion in the important first atmospheric transmission window between 3 and 5 μm can be achieved in robust W-type tellurite fibers pumped at long wavelengths by ultra-fast lasers.

  4. From laboratory to the sky: Th-Ar wavelength standards for the cryogenic infrared echelle spectrograph (CRIRES)

    Energy Technology Data Exchange (ETDEWEB)

    Kerber, Florian; Bristow, Paul [European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching (Germany); Nave, Gillian; Sansonetti, Craig J [National Institute of Standards and Technology, Gaithersburg, MD (United States)], E-mail: fkerber@eso.org, E-mail: gillian.nave@nist.gov, E-mail: craig.sansonetti@nist.gov, E-mail: bristowp@eso.org

    2009-05-15

    We report on the collaborative effort of the European Southern Observatory (ESO) and the National Institute of Standards and Technology (NIST) to establish-through laboratory measurements-wavelength standards in the near-infrared (IR) emission line spectrum of a low current Th-Ar hollow cathode lamp. These standards are now routinely used for the wavelength calibration of the cryogenic infrared echelle spectrograph (CRIRES) operated at one of the unit telescopes of the very large telescope (VLT) at ESO's La Silla Paranal Observatory in Chile. The availability of highly accurate wavelength standards from a commercially available calibration source permits a shift to a new operational paradigm for high-resolution IR spectroscopy. Wavelength calibration no longer has to rely on atmospheric features but can make use of laboratory traceable reference data as is normally done in the ultraviolet and visible regions. This opens the door for more quantitative spectroscopic work in the near-IR. To illustrate the potential impact of this development, we briefly review the current state of affairs in IR astronomy and its projected future. With the advent of the next generation of extremely large ground-based telescopes the IR region will become the most powerful window on the universe within the next 10-15 years. We conclude with a short outlook on the contribution atomic physics can make to this evolution.

  5. Intense, stable and excitation wavelength-independent photoluminescence emission in the blue-violet region from phosphorene quantum dots

    Science.gov (United States)

    Ge, Shuaipeng; Zhang, Lisheng; Wang, Peijie; Fang, Yan

    2016-01-01

    Nanoscale phosphorene quantum dots (PQDs) with few-layer structures were fabricated by pulsed laser ablation of a bulk black phosphorus target in diethyl ether. An intense and stable photoluminescence (PL) emission of the PQDs in the blue-violet wavelength region is clearly observed for the first time, which is attributed to electronic transitions from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) and occupied molecular orbitals below the HOMO (H-1, H-2), respectively. Surprisingly, the PL emission peak positions of the PQDs are not red-shifted with progressively longer excitation wavelengths, which is in contrast to the cases of graphene and molybdenum disulphide quantum dots. This excitation wavelength-independence is derived from the saturated passivation on the periphery and surfaces of the PQDs by large numbers of electron-donating functional groups which cause the electron density on the PQDs to be dramatically increased and the band gap to be insensitive to the quantum size effect in the PQDs. This work suggests that PQDs with intense, stable and excitation wavelength-independent PL emission in the blue-violet region have a potential application as semiconductor-based blue-violet light irradiation sources. PMID:27265198

  6. [Burden and health effects of shift work].

    Science.gov (United States)

    Heitmann, Jörg

    2010-10-01

    In Germany aprox. 15% of all employees have irregular or flexible working hours. Disturbed sleep and/or hypersomnia are direct consequences of shift work and therefore described as shift work disorder. Beyond this, shift work can also be associated with specific pathological disorders. There are individual differences in tolerance to shift work. Optimization of both shift schedules and sleep to "non-physiological" times of the day are measures to counteract the negative effects of shift work. There is still not enough evidence to recommend drugs for routine use in shift workers. © Georg Thieme Verlag Stuttgart · New York.

  7. The wavelength dependence of polarization in NGC 2023

    International Nuclear Information System (INIS)

    Rolph, C. D.; Scarrott, S. M.

    1989-01-01

    NGC 2023 is a bright reflection nebula illuminated by the central star HD37903. At 2 microns the nebula is seen solely by reflected light from the central star but in the NIR there is excess radiation that is supposed to arise from thermal emission from a population of small grains (Sellgren, 1984). The unexpectedly high surface brightness at R and I wavelengths has led to the suggestion that even at these wavelengths there is a significant contribution from this thermal emission process (Witt, Schild, and Kraiman, 1984). If the nebula is seen by reflected starlight then this radiation will be linearly polarized. The level of polarization depends on the scattering geometry, grain size distribution, etc., and is typically 20 to 40 percent for nebulae such as NGC 1999 which is morphologically similar to NGC 2023. If, in any waveband, there is a contribution of radiation from emission processes this radiation will be unpolarized and will serve to dilute the scattered radiation to give a lower level of observed polarization. A study of the wavelength dependence of polarization in nebulae in which there may be thermal emission from grains will indicate the contribution from this process to the total luminosity. Polarization maps were produced in BVRI wavebands for the NGC 2023 nebulosity which confirm that at all wavelengths it is a reflection nebula illuminated by a central star. The wavelength dependence of polarization at representative points in the nebula and in a scatter plot of polarization in V and I wavebands at all points at which measurements are given. Results indicate that throughout the nebula there is a general trend for the level of polarization to increase with wavelength and that maximum levels of polarization occur at the longest wavelengths. No evidence is seen in the data for any significant contribution from the thermal emission from grains in the BVRI luminosity of NGC 2023

  8. Ionic liquids as solvents for Čerenkov counting and the effect of a wavelength shifter.

    Science.gov (United States)

    Mirenda, M; Rodrigues, D; Ferreyra, C; Arenillas, P; Sarmiento, G P; Krimer, N; Japas, M L

    2018-04-01

    We study the wavelength shift of the Čerenkov light - generated in the ionic liquid (BMIMCl) - caused by the addition of the highly fluorescent ionic liquid (BMIMHPTS). 18 F and 32 P efficiencies increases up to 124% and 14%, respectively, compared with the values obtained with pure BMIMCl. With this improvement, ionic liquid mixtures become a good alternative - when using the TDCR-Cherenkov technique - to standardize radionuclides having electron emissions energies close to the threshold energy in water (∼ 260keV). As an advantage compared with other solvents, the Ionic liquid mixture can be reused, in the case of short-lived radionuclides, by simply removing all water content in a vacuum oven. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Performance evaluation of FSO system using wavelength and time diversity over malaga turbulence channel with pointing errors

    Science.gov (United States)

    Balaji, K. A.; Prabu, K.

    2018-03-01

    There is an immense demand for high bandwidth and high data rate systems, which is fulfilled by wireless optical communication or free space optics (FSO). Hence FSO gained a pivotal role in research which has a added advantage of both cost-effective and licence free huge bandwidth. Unfortunately the optical signal in free space suffers from irradiance and phase fluctuations due to atmospheric turbulence and pointing errors which deteriorates the signal and degrades the performance of communication system over longer distance which is undesirable. In this paper, we have considered polarization shift keying (POLSK) system applied with wavelength and time diversity technique over Malaga(M)distribution to mitigate turbulence induced fading. We derived closed form mathematical expressions for estimating the systems outage probability and average bit error rate (BER). Ultimately from the results we can infer that wavelength and time diversity schemes enhances these systems performance.

  10. Stokes shift spectroscopy for the early diagnosis of epithelial precancers in DMBA treated mouse skin carcinogenesis

    Science.gov (United States)

    Jeyasingh, Ebenezar; Singaravelu, Ganesan; Prakasarao, Aruna

    2018-02-01

    In this study, we aim to characterize the tissue transformation in dimethylbenz(a)anthracene (DMBA) treated mouse skin tumor model using stokes shift spectroscopy (SSS) technique for early detection of the neoplastic changes. Stokes shift (SS) spectra measured by scanning both excitation and emission wavelength simultaneously with a fixed wavelength of interval (Δλ=20 nm) in vivo from 33 DMBA treated animals and 6 control animals. The SS spectra of normal (n=6), hyperplasia (n=10), dysplasia (n=10), and WDSCC (n=13) of mice skin shows the distinct peaks around 300, 350, and 386 nm may be attributed to tryptophan, collagen, and NADH respectively. From the observed spectral differences and the ratio variables that resulted in better classification between groups, it is concluded that tryptophan, collagen, and NADH are the key fluorophores that undergo changes during tissue transformation process and hence they can be targeted as tumor markers for early neoplastic changes.

  11. Special training of shift personnel

    International Nuclear Information System (INIS)

    Martin, H.D.

    1981-01-01

    The first step of on-the-job training is practical observation phase in an operating Nuclear Plant, where the participants are assigned to shift work. The simulator training for operating personnel, for key personnel and, to some extent, also for maintenance personnel and specialists give the practical feeling for Nuclear Power Plant behaviour during normal and abnormal conditions. During the commissioning phase of the own Nuclear Power Plant, which is the most important practical training, the participants are integrated into the commissioning staff and assisted during their process of practical learning by special instructors. The preparation for the licensing exams is vitally important for shift personnel and special courses are provided after the first non-nuclear trial operation of the plant. Personnel training also includes performance of programmes and material for retraining, training of instructors and assistance in building up special training programmes and material as well as training centers. (orig./RW)

  12. Single-shot femtosecond-pulsed phase-shifting digital holography.

    Science.gov (United States)

    Kakue, Takashi; Itoh, Seiya; Xia, Peng; Tahara, Tatsuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2012-08-27

    Parallel phase-shifting digital holography is capable of three-dimensional measurement of a dynamically moving object with a single-shot recording. In this letter, we demonstrated a parallel phase-shifting digital holography using a single femtosecond light pulse whose central wavelength and temporal duration were 800 nm and 96 fs, respectively. As an object, we set spark discharge in atmospheric pressure air induced by applying a high voltage to between two electrodes. The instantaneous change in phase caused by the spark discharge was clearly reconstructed. The reconstructed phase image shows the change of refractive index of air was -3.7 × 10(-4).

  13. Shift work as an oxidative stressor

    OpenAIRE

    Pasalar Parvin; Farahani Saeed; Sharifian Akbar; Gharavi Marjan; Aminian Omid

    2005-01-01

    Abstract Background Some medical disorders have higher prevalence in shift workers than others. This study was designed to evaluate the effect of night-shift-working on total plasma antioxidant capacity, with respect to the causative role of oxidative stress in induction of some of these disorders. Methods Two blood samples were taken from 44 workers with a rotational shift schedule, one after their day shift and one after their night shift. The total plasma antioxidant capacity of each worke...

  14. Perihelium shifts in central potentials

    International Nuclear Information System (INIS)

    Amorim, A.E.A.; Ferreira, P.L.

    1987-01-01

    Motivated by the rigorous results on level ordering for arbitrary central potentials recently derived in the literature a classical treatment of the perihelium shifts is presented, based on the consideration of those orbits which lie in the vicinity of a circular orbit. The role played by the Laplacian of the potential is emphasized. By the same approach Bertrand's theorem is also discussed, in connection with Arnold's proof. (Author) [pt

  15. Shift Work and Endocrine Disorders

    Directory of Open Access Journals (Sweden)

    M. A. Ulhôa

    2015-01-01

    Full Text Available The objective of this review was to investigate the impact of shift and night work on metabolic processes and the role of alterations in the sleep-wake cycle and feeding times and environmental changes in the occurrence of metabolic disorders. The literature review was performed by searching three electronic databases for relevant studies published in the last 10 years. The methodological quality of each study was assessed, and best-evidence synthesis was applied to draw conclusions. The literature has shown changes in concentrations of melatonin, cortisol, ghrelin, and leptin among shift workers. Melatonin has been implicated for its role in the synthesis and action of insulin. The action of this hormone also regulates the expression of transporter glucose type 4 or triggers phosphorylation of the insulin receptor. Therefore, a reduction in melatonin can be associated with an increase in insulin resistance and a propensity for the development of diabetes. Moreover, shift work can negatively affect sleep and contribute to sedentarism, unhealthy eating habits, and stress. Recent studies on metabolic processes have increasingly revealed their complexity. Physiological changes induced in workers who invert their activity-rest cycle to fulfill work hours include disruptions in metabolic processes.

  16. PSYCHE Pure Shift NMR Spectroscopy.

    Science.gov (United States)

    Foroozandeh, Mohammadali; Morris, Gareth; Nilsson, Mathias

    2018-03-13

    Broadband homodecoupling techniques in NMR, also known as "pure shift" methods, aim to enhance spectral resolution by suppressing the effects of homonuclear coupling interactions to turn multiplet signals into singlets. Such techniques typically work by selecting a subset of "active" nuclear spins to observe, and selectively inverting the remaining, "passive", spins to reverse the effects of coupling. Pure Shift Yielded by Chirp Excitation (PSYCHE) is one such method; it is relatively recent, but has already been successfully implemented in a range of different NMR experiments. Paradoxically, PSYCHE is one of the trickiest of pure shift NMR techniques to understand but one of the easiest to use. Here we offer some insights into theoretical and practical aspects of the method, and into the effects and importance of the experimental parameters. Some recent improvements that enhance the spectral purity of PSYCHE spectra will be presented, and some experimental frameworks including examples in 1D and 2D NMR spectroscopy, for the implementation of PSYCHE will be introduced. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Ultra-high accuracy optical testing: creating diffraction-limitedshort-wavelength optical systems

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Rekawa, Senajith B.; Denham, Paul E.; Liddle, J. Alexander; Gullikson, Eric M.; Jackson, KeithH.; Anderson, Erik H.; Taylor, John S.; Sommargren, Gary E.; Chapman,Henry N.; Phillion, Donald W.; Johnson, Michael; Barty, Anton; Soufli,Regina; Spiller, Eberhard A.; Walton, Christopher C.; Bajt, Sasa

    2005-08-03

    Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-{angstrom} and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date.

  18. Ultra-high accuracy optical testing: creating diffraction-limited short-wavelength optical systems

    International Nuclear Information System (INIS)

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Rekawa, Senajith B.; Denham, Paul E.; Liddle, J. Alexander; Gullikson, Eric M.; Jackson, KeithH.; Anderson, Erik H.; Taylor, John S.; Sommargren, Gary E.; Chapman, Henry N.; Phillion, Donald W.; Johnson, Michael; Barty, Anton; Soufli, Regina; Spiller, Eberhard A.; Walton, Christopher C.; Bajt, Sasa

    2005-01-01

    Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-(angstrom) and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date

  19. Room temperature performance of mid-wavelength infrared InAsSb nBn detectors

    Energy Technology Data Exchange (ETDEWEB)

    Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Hoglund, Linda; Rosenberg, Robert; Kowalczyk, Robert; Khoshakhlagh, Arezou; Fisher, Anita; Ting, David Z.-Y.; Gunapala, Sarath D. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91030 (United States)

    2014-07-14

    In this work, we investigate the high temperature performance of mid-wavelength infrared InAsSb-AlAsSb nBn detectors with cut-off wavelengths near 4.5 μm. The quantum efficiency of these devices is 35% without antireflection coatings and does not change with temperature in the 77–325 K temperature range, indicating potential for room temperature operation. The current generation of nBn detectors shows an increase of operational bias with temperature, which is attributed to a shift in the Fermi energy level in the absorber. Analysis of the device performance shows that operational bias and quantum efficiency of these detectors can be further improved. The device dark current stays diffusion limited in the 150 K–325 K temperature range and becomes dominated by generation-recombination processes at lower temperatures. Detector detectivities are D*(λ) = 1 × 10{sup 9} (cm Hz{sup 0.5}/W) at T = 300 K and D*(λ) = 5 × 10{sup 9} (cm Hz{sup 0.5}/W) at T = 250 K, which is easily achievable with a one stage TE cooler.

  20. Evaluation of Wavelength Detuning to Mitigate Cross-Beam Energy Transfer Using the Nike Laser

    Science.gov (United States)

    McKenty, P. W.; Marozas, J. A.; Weaver, J.; Obenschain, S. P.; Schmitt, A. J.

    2015-11-01

    Cross-beam energy transfer (CBET) has become a serious threat to the overall success of direct-drive experiments, and especially for polar-direct-drive (PDD) ignition experiments. CBET redirects incident laser light before it can be absorbed into the target, thereby degrading overall target performance. CBET is particularly detrimental over the equator of the target, which is hydrodynamically very sensitive to such losses in the PDD configuration. A promising solution uses laser wavelength detuning between beams to shift the resonance, thereby reducing the interaction cross section between them. Testing this process for direct drive is now underway at the Nike laser at the Naval Research Laboratory. Calculations evaluating the effect CBET has on the scattered-light signals indicate such an experiment will demonstrate the benefits of wavelength detuning for direct-drive implosions. Two-dimensional simulation results will be presented, predicting the effect for both spherical and cylindrical experiments. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  1. New long-wavelength Nd:YAG laser at 1.44 micron: effect on brain.

    Science.gov (United States)

    Martiniuk, R; Bauer, J A; McKean, J D; Tulip, J; Mielke, B W

    1989-02-01

    A wavelength-shifted Nd:YAG laser, tuned to coincide with the infrared absorption peak of water at 1.44 microns, was used to make lesions in normal rabbit brain. A total of 48 lesions were made with power up to 20 W, with energy up to 40 joules, and with two different spot sizes. These lesions were compared to lesions made with 1.06 microns radiation from an Nd:YAG laser under identical operating conditions. Measurements of blood-brain barrier damage and width, depth, and volume of tissue affected were obtained 30 minutes after placement of the lesions. It was found that 1.44-microns lesions produced photoevaporative tissue loss at the highest intensities used. The layer of coagulated tissue remaining after photovaporization had a mean thickness of 0.6 mm irrespective of the volume of tissue removed. There was no photovaporization in the 1.06-microns lesions. In addition, the amount of peripheral edema per unit volume of tissue coagulated was approximately half at the 1.44-microns wavelength. These findings suggest that the 1.44-microns Nd:YAG laser may be a useful surgical instrument since it combines the photoevaporative effect of the CO2 laser while maintaining the advantages of the conventional Nd:YAG laser (quartz fiber delivery and effective hemostasis).

  2. A segmented scintillator-lead photon calorimeter using a double wavelength shifter optical readout system

    International Nuclear Information System (INIS)

    Fent, J.; Fessler, H.; Freund, P.; Gebauer, H.J.; Polakos, P.; Pretzl, K.P.; Schouten, T.; Seyboth, P.; Seyerlein, J.

    1982-11-01

    The construction and performance of a prototype scintillator-lead photon calorimeter using a double wavelength shifter optical readout is described. The calorimeter is divided into 4 individual cells each consisting of 44 layers of 3 mm lead plus 1 cm thick scintillator. The edges of each scintillator plate are covered by acrylic bars doped with a wavelength shifting material. The light produced in each scintillator plate is first converted in these bars, then converted a second time in a set of acrylic rods which run longitudinally through the calorimeter along the corners of each calorimeter cell. A photomultiplier is attached to each of these rods at the back end of the calorimeter. The energy resolution obtained with incident electrons in the energy range of 2-30 GeV is sigma/E = 0.12/√E. The uniformity of response across the front face of each cell was measured. Showers within each cell can be localised with an accuracy of better than sigma = 7 mm. (orig.)

  3. All-optical 40 Gbit/s compact integrated interferometric wavelength converter

    DEFF Research Database (Denmark)

    Jørgensen, Carsten; Danielsen, Søren Lykke; Hansen, Peter Bukhave

    1997-01-01

    An interferometric Michelson wavelength converter is presented that combines a speed-optimized semiconductor optical amplifier technology with the benefits of the integrated interferometer showing 40-Gbit/s wavelength conversion. The optimized wavelength converter demonstrates noninverted converted...

  4. Wavelength conversion, time demultiplexing and multicasting based on cross-phase modulation and four-wave mixing in dispersion-flattened highly nonlinear photonic crystal fiber

    International Nuclear Information System (INIS)

    Hui, Zhan-Qiang; Zhang, Jian-Guo

    2012-01-01

    We propose the use of cross-phase modulation (XPM) and four-wave mixing (FWM) in dispersion-flattened highly nonlinear photonic crystal fibers (HNL-PCFs) to implement the functionalities of wavelength conversion, simultaneous time demultiplexing and wavelength multicasting in optical time-division multiplexing (OTDM) systems. The experiments on wavelength conversion at 80 Gbit s −1 and OTDM demultiplexing from 80 to 10 Gbit s −1 with wavelength multicasting of two channels are successfully demonstrated to validate the proposed scheme, which are carried out by using two segments of dispersion-flattened HNL-PCFs with lengths of 100 and 50 m, respectively. Moreover, the bit error rate (BER) performance is also measured. The results show that our designed system can achieve a power penalty of less than 4.6 dB for two multicasting channels with a 24 nm wavelength span at the BER of 10 −9 when compared with the 10 Gbit/s back-to-back measurement. The proposed system is transparent to bit rate since only an ultrafast third-order nonlinear effect is used. The resulting configuration is compact, robust and reliable, benefiting from the use of dispersion-flattened HNL-PCFs with short lengths. This also makes the proposed system more flexible in the operational wavelengths than those based on dispersion-shifted fibers and traditional highly nonlinear fibers. (paper)

  5. Toward A Neutral Mercury Optical Lattice Clock: Determination of the Magic Wavelength for the Ultraviolet clock Transition

    International Nuclear Information System (INIS)

    Mejri, Sinda

    2012-01-01

    A lattice clock combines the advantages of ion and neutral atom based clocks, namely the recoil and first order Doppler free spectroscopy allowed by the Lamb-Dicke regime. This lattice light field shifts the energy levels of the clock transition. However a wavelength can be found where the light-shift of the clock states cancelled to first order. In this thesis, we present the latest advances in optical lattice clock with mercury atoms developed at LNE-SYRTE. After a review of the current performances of different optical clock are currently under development, we focus on the concept of optical lattice clock and the features of the mercury that make him an excellent candidate for the realization of an optical lattice clock achievement the uncertainty of the level of 10 -17 . The second part is devoted to the characterization of the mercury MOT, using a sensitive detection system, which allowed us to evaluate the temperature of different isotopes present in the MOT and have a good evidence of sub-Doppler cooling for the fermionic isotopes. The third part of this these, present the experimental aspects of the implementation and the development of the laser source required for trapping mercury atoms operating near the predicted magic wavelength. Finally, we report on the Lamb-Dicke spectroscopy of the 1S0 →3 P0 clock transition in the 199 Hg atoms confined in lattice trap. With use of the ultra-stable laser system, linked to LNE-SYRTE primary frequency reference, we have determined the center frequency of the transition for a range of lattice wavelengths and different lattice depths. Analyzing these measurement, we have carried out the first experimental determination of the magic wavelength, which is the crucial step towards achieving a highly accurate frequency standard using mercury. (author)

  6. Moiré phase-shifted fiber Bragg gratings in polymer optical fibers

    Science.gov (United States)

    Min, Rui; Marques, Carlos; Bang, Ole; Ortega, Beatriz

    2018-03-01

    We demonstrate a simple way to fabricate phase-shifted fiber Bragg grating in polymer optical fibers as a narrowband transmission filter for a variety of applications at telecom wavelengths. The filters have been fabricated by overlapping two uniform fiber Bragg gratings with slightly different periods to create a Moiré grating with only two pulses (one pulse is 15 ns) of UV power. Experimental characterization of the filter is provided under different conditions where the strain and temperature sensitivities were measured.

  7. Dynamical resonance shift and unification of resonances in short-pulse laser-cluster interaction

    Science.gov (United States)

    Mahalik, S. S.; Kundu, M.

    2018-06-01

    Pronounced maximum absorption of laser light irradiating a rare-gas or metal cluster is widely expected during the linear resonance (LR) when Mie-plasma wavelength λM of electrons equals the laser wavelength λ . On the contrary, by performing molecular dynamics (MD) simulations of an argon cluster irradiated by short 5-fs (FWHM) laser pulses it is revealed that, for a given laser pulse energy and a cluster, at each peak intensity there exists a λ —shifted from the expected λM—that corresponds to a unified dynamical LR at which evolution of the cluster happens through very efficient unification of possible resonances in various stages, including (i) the LR in the initial time of plasma creation, (ii) the LR in the Coulomb expanding phase in the later time, and (iii) anharmonic resonance in the marginally overdense regime for a relatively longer pulse duration, leading to maximum laser absorption accompanied by maximum removal of electrons from cluster and also maximum allowed average charge states for the argon cluster. Increasing the laser intensity, the absorption maxima is found to shift to a higher wavelength in the band of λ ≈(1 -1.5 ) λM than permanently staying at the expected λM. A naive rigid sphere model also corroborates the wavelength shift of the absorption peak as found in MD and unequivocally proves that maximum laser absorption in a cluster happens at a shifted λ in the marginally overdense regime of λ ≈(1 -1.5 ) λM instead of λM of LR. The present study is important for guiding an optimal condition laser-cluster interaction experiment in the short-pulse regime.

  8. Selection of Quantum Dot Wavelengths for Biomedical Assays and Imaging

    Directory of Open Access Journals (Sweden)

    Yong Taik Lim

    2003-01-01

    Full Text Available Fluorescent semiconductor nanocrystals (quantum dots [QDs] are hypothesized to be excellent contrast agents for biomedical assays and imaging. A unique property of QDs is that their absorbance increases with increasing separation between excitation and emission wavelengths. Much of the enthusiasm for using QDs in vivo stems from this property, since photon yield should be proportional to the integral of the broadband absorption. In this study, we demonstrate that tissue scatter and absorbance can sometimes offset increasing QD absorption at bluer wavelengths, and counteract this potential advantage. By using a previously validated mathematical model, we explored the effects of tissue absorbance, tissue scatter, wavelength dependence of the scatter, water-to- hemoglobin ratio, and tissue thickness on QD performance. We conclude that when embedded in biological fluids and tissues, QD excitation wavelengths will often be quite constrained, and that excitation and emission wavelengths should be selected carefully based on the particular application. Based on our results, we produced near-infrared QDs optimized for imaging surface vasculature with white light excitation and a silicon CCD camera, and used them to image the coronary vasculature in vivo. Taken together, our data should prove useful in designing fluorescent QD contrast agents optimized for specific biomedical applications.

  9. A Multi-Wavelength IR Laser for Space Applications

    Science.gov (United States)

    Li, Steven X.; Yu, Anthony W.; Sun, Xiaoli; Fahey, Molly E.; Numata, Kenji; Krainak, Michael A.

    2017-01-01

    We present a laser technology development with space flight heritage to generate laser wavelengths in the near- to mid-infrared (NIR to MIR) for space lidar applications. Integrating an optical parametric crystal to the LOLA (Lunar Orbiter Laser Altimeter) laser transmitter design affords selective laser wavelengths from NIR to MIR that are not easily obtainable from traditional diode pumped solid-state lasers. By replacing the output coupler of the LOLA laser with a properly designed parametric crystal, we successfully demonstrated a monolithic intra-cavity optical parametric oscillator (iOPO) laser based on all high technology readiness level (TRL) subsystems and components. Several desired wavelengths have been generated including 2.1 microns, 2.7 microns and 3.4 microns. This laser can also be used in trace-gas remote sensing, as many molecules possess their unique vibrational transitions in NIR to MIR wavelength region, as well as in time-of-flight mass spectrometer where desorption of samples using MIR laser wavelengths have been successfully demonstrated.

  10. Multi-Wavelength Photomagnetic Imaging for Oral Cancer

    Science.gov (United States)

    Marks, Michael

    In this study, a multi-wavelength Photomagnetic Imaging (PMI) system is developed and evaluated with experimental studies.. PMI measures temperature increases in samples illuminated by near-infrared light sources using magnetic resonance thermometry. A multiphysics solver combining light and heat transfer models the spatiotemporal distribution of the temperature change. The PMI system develop in this work uses three lasers of varying wavelength (785 nm, 808 nm, 860 nm) to heat the sample. By using multiple wavelengths, we enable the PMI system to quantify the relative concentrations of optical contrast in turbid media and monitor their distribution, at a higher resolution than conventional diffuse optical imaging. The data collected from agarose phantoms with multiple embedded contrast agents designed to simulate the optical properties of oxy- and deoxy-hemoglobin is presented. The reconstructed images demonstrate that multi-wavelength PMI can resolve this complex inclusion structure with high resolution and recover the concentration of each contrast agent with high quantitative accuracy. The modified multi-wavelength PMI system operates under the maximum skin exposure limits defined by the American National Standards Institute, to enable future clinical applications.

  11. Choice of the laser wavelength for a herpetic keratitis treatment

    Science.gov (United States)

    Razhev, Alexander M.; Bagayev, Sergei N.; Chernikh, Valery V.; Kargapoltsev, Evgeny S.; Trunov, Alexander; Zhupikov, Andrey A.

    2002-06-01

    For the first time the effect of the UV laser radiation to human eye cornea with herpetic keratitis was experimentally investigated. In experiments the UV radiation of ArF (193 nm), KrCl (223 nm), KrF (248 nm) excimer lasers were used. Optimal laser radiation parameters for the treatment of the herpetic keratitis were determined. The immuno-biochemical investigations were carried out and the results of clinical trials are presented. The maximum ablation rate was obtained for the 248 nm radiation wavelength. The process of healing was successful but in some cases the haze on the surface of the cornea was observed. When used the 193 nm radiation wavelength the corneal surface was clear without any hazes but the epithelization process was slower than for 248 nm wavelength and in some cases the relapse was occurred. The best results for herpetic keratitis treatment have been achieved by utilizing the 223 nm radiation wavelength of the KrCl excimer laser. The use of the 223 nm radiation wavelength allows treating the herpetic keratitis with low traumatic process of ablation and provides high quality of corneal surface.

  12. Study of the correlation of scintillation decay and emission wavelength

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Yamaji, Akihiro; Kawaguchi, Noriaki; Kamada, Kei; Totsuka, Daisuke; Fukuda, Kentaro; Yamanoi, Kohei; Nishi, Ryosuke; Kurosawa, Shunsuke; Shimizu, Toshihiko; Sarukura, Nobuhiko

    2013-01-01

    In photoluminescence which directly excites the emission center of phosphor material is known to have a correlation between the emission wavelength and the decay time based on quantum mechanics. In scintillation phenomenon, host lattice of the material is first excited by ionizing radiation and then the excitation energy is transferred to emission centers. For the first time, we investigated the correlation between the scintillation decay and the emission wavelength by using pulse X-ray equipped streak camera system which could observe time and wavelength resolved scintillation phenomenon. Investigated materials were Ce 3+ , Pr 3+ and Nd 3+ doped oxides and fluorides which all showed 5d-4f transition based emission. As a result, we obtained the relation that τ (scintillation decay time) was proportional to the λ 2.15 (emission wavelength). -- Highlights: ► The correlation between emission wavelength and scintillation decay time is investigated. ► Photoluminescence decay times are also evaluated and compared with scintillation decay times. ► It is proved the relaxation process in emission center is dominant even in scintillation decay

  13. Time evolution, Lamb shift, and emission spectra of spontaneous emission of two identical atoms

    International Nuclear Information System (INIS)

    Wang Dawei; Li Zhenghong; Zheng Hang; Zhu Shiyao

    2010-01-01

    A unitary transformation method is used to investigate the dynamic evolution of two multilevel atoms, in the basis of symmetric and antisymmetric states, with one atom being initially prepared in the first excited state and the other in the ground state. The unitary transformation guarantees that our calculations are based on the ground state of the atom-field system and the self-energy is subtracted at the beginning. The total Lamb shifts of the symmetric and antisymmetric states are divided into transformed shift and dynamic shift. The transformed shift is due to emitting and reabsorbing of virtual photons, by a single atom (nondynamic single atomic shift) and between the two atoms (quasi-static shift). The dynamic shift is due to the emitting and reabsorbing of real photons, by a single atom (dynamic single atomic shift) and between the two atoms (dynamic interatomic shift). The emitting and reabsorbing of virtual and real photons between the two atoms result in the interatomic shift, which does not exist for the one-atom case. The spectra at the long-time limit are calculated. If the distance between the two atoms is shorter than or comparable to the wavelength, the strong coupling between the two atoms splits the spectrum into two peaks, one from the symmetric state and the other from the antisymmetric state. The origin of the red or blue shifts for the symmetric and antisymmetric states mainly lies in the negative or positive interaction energy between the two atoms. In the investigation of the short time evolution, we find the modification of the effective density of states by the interaction between two atoms can modulate the quantum Zeno and quantum anti-Zeno effects in the decays of the symmetric and antisymmetric states.

  14. Wavelength selection in traveling-wave convection in a fluid mixture

    International Nuclear Information System (INIS)

    Surko, C.M.; Eaton, K.D.; Baxter, G.W.; Iwata, K.

    1993-01-01

    The mechanisms by which a one-dimensional pattern of traveling waves changes wavelength (i.e. the Eckhaus instability) is studied in a binary fluid mixture. Propagating wavelength modulations develop when the Rayleigh number of the system is decreased below a wavelength-dependent threshold, commonly referred to as the Eckhaus boundary. These wavelength modulations increase in amplitude and narrow in spatial extent until they trigger the creation or annihilation of convection roll pairs and thereby change the average wavelength of the system. The authors find qualitatively different dynamics for wavelength-increasing events and wavelength-decreasing events; these differences are due to the strong wavelength dependence of the group velocity

  15. Effect of graphene on plasmonic metasurfaces at infrared wavelengths

    Directory of Open Access Journals (Sweden)

    Shinpei Ogawa

    2013-11-01

    Full Text Available Significant enhancement of infrared transmittance by the presence of a graphene layer on a plasmonic metasurface (PLM has been demonstrated. PLMs with different configurations were fabricated, and their transmittance with and without graphene was compared. Selective enhancement by graphene occurred at the plasmon resonance wavelength. The degree of enhancement was found to depend on the width of the gap between the periodic metal regions in the PLM. A maximum enhancement of ∼210% was achieved at a wavelength of 10 μm. The ability to achieve such a drastic increase in transmittance at the plasmon resonant wavelength is expected to lead to improvements in the performance of energy collecting devices and optical sensors.

  16. In-vacuum long-wavelength macromolecular crystallography.

    Science.gov (United States)

    Wagner, Armin; Duman, Ramona; Henderson, Keith; Mykhaylyk, Vitaliy

    2016-03-01

    Structure solution based on the weak anomalous signal from native (protein and DNA) crystals is increasingly being attempted as part of synchrotron experiments. Maximizing the measurable anomalous signal by collecting diffraction data at longer wavelengths presents a series of technical challenges caused by the increased absorption of X-rays and larger diffraction angles. A new beamline at Diamond Light Source has been built specifically for collecting data at wavelengths beyond the capability of other synchrotron macromolecular crystallography beamlines. Here, the theoretical considerations in support of the long-wavelength beamline are outlined and the in-vacuum design of the endstation is discussed, as well as other hardware features aimed at enhancing the accuracy of the diffraction data. The first commissioning results, representing the first in-vacuum protein structure solution, demonstrate the promising potential of the beamline.

  17. Method of stabilizing a laser apparatus with wavelength converter

    DEFF Research Database (Denmark)

    2013-01-01

    and to output the frequency-converted radiation (213), the frequency-converted radiation having at least a second wavelength different from the first wavelength, the diode laser (10) comprising at least a first and a second section (222,223), a first contact (220) for injecting a first current (I1......) into the first section (222), a second contact (221) for injecting a second current (I2) into the second section (223), and means for controlling a temperature of the diode laser; wherein the method comprises monitoring a first parameter indicative of the power content of a dominant lobe of the first radiation......A method of controlling beam quality and stability of a laser apparatus, the laser apparatus comprising, a diode laser (10) providing first radiation of at least a first wavelength, and a frequency conversion unit (12) configured to frequency-convert the first radiation from the diode laser...

  18. Do shorter wavelengths improve contrast in optical mammography?

    International Nuclear Information System (INIS)

    Taroni, P; Pifferi, A; Torricelli, A; Spinelli, L; Danesini, G M; Cubeddu, R

    2004-01-01

    The detection of tumours with time-resolved transmittance imaging relies essentially on blood absorption. Previous theoretical and phantom studies have shown that both contrast and spatial resolution of optical images are affected by the optical properties of the background medium, and high absorption and scattering are generally beneficial. Based on these observations, wavelengths shorter than presently used (680-780 nm) could be profitable for optical mammography. A study was thus performed analysing time-resolved transmittance images at 637, 656, 683 and 785 nm obtained from 26 patients bearing 16 tumours and 15 cysts. The optical contrast proved to increase upon decreasing wavelengths for the detection of cancers in late-gated intensity images, with higher gain in contrast for lesions of smaller size (<1.5 cm diameter). For cysts either a progressive increase or decrease in contrast with wavelength was observed in scattering images

  19. Cluster dynamics at different cluster size and incident laser wavelengths

    International Nuclear Information System (INIS)

    Desai, Tara; Bernardinello, Andrea

    2002-01-01

    X-ray emission spectra from aluminum clusters of diameter -0.4 μm and gold clusters of dia. ∼1.25 μm are experimentally studied by irradiating the cluster foil targets with 1.06 μm laser, 10 ns (FWHM) at an intensity ∼10 12 W/cm 2 . Aluminum clusters show a different spectra compared to bulk material whereas gold cluster evolve towards bulk gold. Experimental data are analyzed on the basis of cluster dimension, laser wavelength and pulse duration. PIC simulations are performed to study the behavior of clusters at higher intensity I≥10 17 W/cm 2 for different size of the clusters irradiated at different laser wavelengths. Results indicate the dependence of cluster dynamics on cluster size and incident laser wavelength

  20. Enhanced Plasmonic Wavelength Selective Infrared Emission Combined with Microheater

    Directory of Open Access Journals (Sweden)

    Hiroki Ishihara

    2017-09-01

    Full Text Available The indirect wavelength selective thermal emitter that we have proposed is constructed using a new microheater, demonstrating the enhancement of the emission peak generated by the surface plasmon polariton. The thermal isolation is improved using a 2 μm-thick Si membrane having 3.6 and 5.4 mm outer diameter. The emission at around the wavelength of the absorption band of CO2 gas is enhanced. The absorption signal increases, confirming the suitability for gas sensing. Against input power, the intensity at the peak wavelength shows a steeper increasing ratio than the background intensity. The microheater with higher thermal isolation gives larger peak intensity and its increasing ratio against the input power.

  1. Electrically tunable zero dispersion wavelengths in photonic crystal fibers filled with a dual frequency addressable liquid crystal

    International Nuclear Information System (INIS)

    Wahle, Markus; Kitzerow, Heinz-Siegfried

    2015-01-01

    We present a liquid crystal (LC) infiltrated photonic crystal fiber, which enables the electrical tuning of the position of zero dispersion wavelengths (ZDWs). A dual frequency addressable liquid crystal is aligned perpendicular on the inclusion walls of a photonic crystal fiber, which results in an escaped radial director field. The orientation of the LC is controlled by applying an external electric field. Due to the high index of the liquid crystal the fiber guides light by the photonic band gap effect. Multiple ZDWs exist in the visible and near infrared. The positions of the ZDWs can be either blue or red shifted depending on the frequency of the applied voltage

  2. Visual attention shifting in autism spectrum disorders.

    Science.gov (United States)

    Richard, Annette E; Lajiness-O'Neill, Renee

    2015-01-01

    Abnormal visual attention has been frequently observed in autism spectrum disorders (ASD). Abnormal shifting of visual attention is related to abnormal development of social cognition and has been identified as a key neuropsychological finding in ASD. Better characterizing attention shifting in ASD and its relationship with social functioning may help to identify new targets for intervention and improving social communication in these disorders. Thus, the current study investigated deficits in attention shifting in ASD as well as relationships between attention shifting and social communication in ASD and neurotypicals (NT). To investigate deficits in visual attention shifting in ASD, 20 ASD and 20 age- and gender-matched NT completed visual search (VS) and Navon tasks with attention-shifting demands as well as a set-shifting task. VS was a feature search task with targets defined in one of two dimensions; Navon required identification of a target letter presented at the global or local level. Psychomotor and processing speed were entered as covariates. Relationships between visual attention shifting, set shifting, and social functioning were also examined. ASD and NT showed comparable costs of shifting attention. However, psychomotor and processing speed were slower in ASD than in NT, and psychomotor and processing speed were positively correlated with attention-shifting costs on Navon and VS, respectively, for both groups. Attention shifting on VS and Navon were correlated among NT, while attention shifting on Navon was correlated with set shifting among ASD. Attention-shifting costs on Navon were positively correlated with restricted and repetitive behaviors among ASD. Relationships between attention shifting and psychomotor and processing speed, as well as relationships between measures of different aspects of visual attention shifting, suggest inefficient top-down influences over preattentive visual processing in ASD. Inefficient attention shifting may be

  3. Broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity

    Science.gov (United States)

    Li, Q.; Jia, Z. X.; Weng, H. Z.; Li, Z. R.; Yang, Y. D.; Xiao, J. L.; Chen, S. W.; Huang, Y. Z.; Qin, W. P.; Qin, G. S.

    2018-05-01

    We demonstrate broadband multi-wavelength Brillouin lasers with an operating wavelength range of 1500–1600 nm and a frequency separation of ~9.28 GHz generated by four-wave mixing in a dual wavelength Brillouin fiber laser cavity. By using one continuous-wave laser as the pump source, multi-wavelength Brillouin lasers with an operating wavelength range of 1554–1574 nm were generated via cascaded Brillouin scattering and four-wave mixing. Interestingly, when pumped by two continuous-wave lasers with an appropriate frequency separation, the operating wavelength range of the multi-wavelength Brillouin lasers was increased to 1500–1600 nm due to cavity-enhanced cascaded four-wave mixing among the frequency components generated by two pump lasers in the dual wavelength Brillouin laser cavity.

  4. Three wavelength optical alignment of the Nova laser

    International Nuclear Information System (INIS)

    Swift, C.D.; Bliss, E.S.; Jones, W.A.; Seppala, L.G.

    1983-01-01

    The Nova laser, presently under construction at Lawrence Livermore National Laboratory, will be capable of delivering more than 100 kJ of focused energy to an Inertial Confinement Fusion (ICF) target. Operation at the fundamental wavelength of the laser (1.05 μm) and at the second and third harmonic will be possible. This paper will discuss the optical alignment systems and techniques being implemented to align the laser output to the target at these wavelengths prior to each target irradiation. When experiments require conversion of the laser light to wavelengths of 0.53 μm and 0.35 μm prior to target irradiation, this will be accomplished in harmonic conversion crystals located at the beam entrances to the target chamber. The harmonic alignment system will be capable of introducing colinear alignment beams of all three wavelengths into the laser chains at the final spatial filter. The alignment beam at 1.05 μm will be about three cm in diameter and intense enough to align the conversion crystals. Beams at 0.53 μm and 0.35 μm will be expanded by the spatial filter to full aperture (74 cm) and used to illuminate the target and other alignment aids at the target chamber focus. This harmonic illumination system will include viewing capability as well. A final alignment sensor will be located at the target chamber. It will view images of the chamber focal plane at all three wavelengths. In this way, each beam can be aligned at the desired wavelength to produce the focal pattern required for each target irradiation. The design of the major components in the harmonic alignment system will be described, and a typical alignment sequence for alignment to a target will be presented

  5. Analysis of calibration-free wavelength-scanned wavelength modulation spectroscopy for practical gas sensing using tunable diode lasers

    Science.gov (United States)

    Sun, K.; Chao, X.; Sur, R.; Goldenstein, C. S.; Jeffries, J. B.; Hanson, R. K.

    2013-12-01

    A novel strategy has been developed for analysis of wavelength-scanned, wavelength modulation spectroscopy (WMS) with tunable diode lasers (TDLs). The method simulates WMS signals to compare with measurements to determine gas properties (e.g., temperature, pressure and concentration of the absorbing species). Injection-current-tuned TDLs have simultaneous wavelength and intensity variation, which severely complicates the Fourier expansion of the simulated WMS signal into harmonics of the modulation frequency (fm). The new method differs from previous WMS analysis strategies in two significant ways: (1) the measured laser intensity is used to simulate the transmitted laser intensity and (2) digital lock-in and low-pass filter software is used to expand both simulated and measured transmitted laser intensities into harmonics of the modulation frequency, WMS-nfm (n = 1, 2, 3,…), avoiding the need for an analytic model of intensity modulation or Fourier expansion of the simulated WMS harmonics. This analysis scheme is valid at any optical depth, modulation index, and at all values of scanned-laser wavelength. The method is demonstrated and validated with WMS of H2O dilute in air (1 atm, 296 K, near 1392 nm). WMS-nfm harmonics for n = 1 to 6 are extracted and the simulation and measurements are found in good agreement for the entire WMS lineshape. The use of 1f-normalization strategies to realize calibration-free wavelength-scanned WMS is also discussed.

  6. Cycle 24 COS FUV Internal/External Wavelength Scale Monitor

    Science.gov (United States)

    Fischer, William J.

    2018-02-01

    We report on the monitoring of the COS FUV wavelength scale zero-points during Cycle 24 in program 14855. Select cenwaves were monitored for all FUV gratings at Lifetime Position 3. The target and cenwaves have remained the same since Cycle 21, with a change only to the target acquisition sequence. All measured offsets are within the error goals, although the G140L cenwaves show offsets at the short-wavelength end of segment A that are approaching the tolerance. This behavior will be closely monitored in subsequent iterations of the program.

  7. Intensities of decimetric-wavelength radio recombination lines

    International Nuclear Information System (INIS)

    Parrish, A.; Pankonin, V.

    1975-01-01

    We summarize the intensity results of some of the 221 and 248α recombination-line observations taken with the Arecibo telescope, and report additional results including 166α observations from the NRAO 300-foot (91 m) telescope. The brightness temperatures of these lines increase sharply with wavelength. We show that these results require that the upper levels of the recombining atoms be overpopulated with respect to LTE conditions. The most reasonable interpretation of the results is that the line emission at these decimetric wavelengths is stimulated by a background source of continuum radiation

  8. Single-wavelength functional photoacoustic microscopy in biological tissue.

    Science.gov (United States)

    Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V

    2011-03-01

    Recently, we developed a reflection-mode relaxation photoacoustic microscope, based on saturation intensity, to measure picosecond relaxation times using a nanosecond laser. Here, using the different relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, the oxygen saturation was quantified in vivo with single-wavelength photoacoustic microscopy. All previous functional photoacoustic microscopy measurements required imaging with multiple-laser-wavelength measurements to quantify oxygen saturation. Eliminating the need for multiwavelength measurements removes the influence of spectral properties on oxygenation calculations and improves the portability and cost-effectiveness of functional or molecular photoacoustic microscopy.

  9. OMEGA: a short-wavelength laser for fusion experiments

    International Nuclear Information System (INIS)

    Soures, J.M.; Hutchison, R.J.; Jacobs, S.D.; Lund, L.D.; McCrory, R.L.; Richardson, M.C.

    1983-01-01

    The OMEGA, Nd:glass laser facility was constructed for the purpose of investigating the feasibility of direct-drive laser fusion. With 24 beams producing a total energy of 4 kJ or a peak power of 12 TW, OMEGA is capable of nearly uniform illumination of spherical targets. Six of the OMEGA beams have recently been converted to short-wavelength operation (351 nm). In this paper, we discuss details of the system design and performance, with particular emphasis on the frequency-conversion system and multi-wavelength diagnostic system

  10. Wavelength-encoded OCDMA system using opto-VLSI processors.

    Science.gov (United States)

    Aljada, Muhsen; Alameh, Kamal

    2007-07-01

    We propose and experimentally demonstrate a 2.5 Gbits/sper user wavelength-encoded optical code-division multiple-access encoder-decoder structure based on opto-VLSI processing. Each encoder and decoder is constructed using a single 1D opto-very-large-scale-integrated (VLSI) processor in conjunction with a fiber Bragg grating (FBG) array of different Bragg wavelengths. The FBG array spectrally and temporally slices the broadband input pulse into several components and the opto-VLSI processor generates codewords using digital phase holograms. System performance is measured in terms of the autocorrelation and cross-correlation functions as well as the eye diagram.

  11. An algorithm for link restoration of wavelength routing optical networks

    DEFF Research Database (Denmark)

    Limal, Emmanuel; Stubkjær, Kristian

    1999-01-01

    We present an algorithm for restoration of single link failure in wavelength routing multihop optical networks. The algorithm is based on an innovative study of networks using graph theory. It has the following original features: it (i) assigns working and spare channels simultaneously, (ii......) prevents the search for unacceptable routing paths by pointing out channels required for restoration, (iii) offers a high utilization of the capacity resources and (iv) allows a trivial search for the restoration paths. The algorithm is for link restoration of networks without wavelength translation. Its...

  12. Wavelength-encoded OCDMA system using opto-VLSI processors

    Science.gov (United States)

    Aljada, Muhsen; Alameh, Kamal

    2007-07-01

    We propose and experimentally demonstrate a 2.5 Gbits/sper user wavelength-encoded optical code-division multiple-access encoder-decoder structure based on opto-VLSI processing. Each encoder and decoder is constructed using a single 1D opto-very-large-scale-integrated (VLSI) processor in conjunction with a fiber Bragg grating (FBG) array of different Bragg wavelengths. The FBG array spectrally and temporally slices the broadband input pulse into several components and the opto-VLSI processor generates codewords using digital phase holograms. System performance is measured in terms of the autocorrelation and cross-correlation functions as well as the eye diagram.

  13. Aperture Mask for Unambiguous Parity Determination in Long Wavelength Imagers

    Science.gov (United States)

    Bos, Brent

    2011-01-01

    A document discusses a new parity pupil mask design that allows users to unambiguously determine the image space coordinate system of all the James Webb Space Telescope (JWST) science instruments by using two out-of-focus images. This is an improvement over existing mask designs that could not completely eliminate the coordinate system parity ambiguity at a wavelength of 5.6 microns. To mitigate the problem of how the presence of diffraction artifacts can obscure the pupil mask detail, this innovation has been created with specifically designed edge features so that the image space coordinate system parity can be determined in the presence of diffraction, even at long wavelengths.

  14. Aluminum nitride nanophotonic circuits operating at ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Stegmaier, M.; Ebert, J.; Pernice, W. H. P., E-mail: wolfram.pernice@kit.edu [Institute of Nanotechnology, Karlsruhe Institute of Technology, 76133 Karlsruhe (Germany); Meckbach, J. M.; Ilin, K.; Siegel, M. [Institute of Micro- und Nanoelectronic Systems, Karlsruhe Institute of Technology, 76187 Karlsruhe (Germany)

    2014-03-03

    Aluminum nitride (AlN) has recently emerged as a promising material for integrated photonics due to a large bandgap and attractive optical properties. Exploiting the wideband transparency, we demonstrate waveguiding in AlN-on-Insulator circuits from near-infrared to ultraviolet wavelengths using nanophotonic components with dimensions down to 40 nm. By measuring the propagation loss over a wide spectral range, we conclude that both scattering and absorption of AlN-intrinsic defects contribute to strong attenuation at short wavelengths, thus providing guidelines for future improvements in thin-film deposition and circuit fabrication.

  15. Laboratory study of nitrate photolysis in Antarctic snow. II. Isotopic effects and wavelength dependence

    Energy Technology Data Exchange (ETDEWEB)

    Berhanu, Tesfaye A.; Erbland, Joseph; Savarino, Joël [Laboratoire de Glaciologie et Géophysique de l’Environnement, CNRS, F-38041 Grenoble (France); Univ. Grenoble Alpes, LGGE, F-38041 Grenoble (France); Meusinger, Carl; Johnson, Matthew S. [Copenhagen Center for Atmospheric Research (CCAR), Department of Chemistry, University of Copenhagen, Copenhagen (Denmark); Jost, Rémy [Laboratoire de Interdisciplinaire de Physique (LIPHY) Univ. de Grenoble, Grenoble (France); Bhattacharya, S. K. [Research Center for Environmental Changes, Academia Sinica, Nangang, Taipei 115, Taiwan (China)

    2014-06-28

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [“Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry,” J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate ({sup 15}N, {sup 17}O, and {sup 18}O) provide additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters. The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ{sup 15}N, δ{sup 18}O, and Δ{sup 17}O). From these measurements an average photolytic isotopic fractionation of {sup 15}ε = (−15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation of the intense absorption band of nitrate around 200 nm in addition to the weaker band centered at 305 nm followed by photodissociation. An experiment with a filter blocking wavelengths shorter than 320 nm, approximating the actinic flux spectrum at Dome C, yielded a photolytic isotopic fractionation of {sup 15}ε = (−47.9 ± 6.8)‰, in good agreement with fractionations determined by previous studies for the East Antarctic Plateau which range from −40 to −74.3‰. We describe a new semi-empirical zero point energy shift model used to derive the absorption cross sections of {sup 14}NO{sub 3}{sup −} and {sup 15}NO{sub 3}{sup −} in snow at a chosen temperature. The nitrogen isotopic fractionations obtained by applying

  16. Noninvasive optical inhibition with a red-shifted microbial rhodopsin

    DEFF Research Database (Denmark)

    Chuong, Amy S; Miri, Mitra L; Busskamp, Volker

    2014-01-01

    Optogenetic inhibition of the electrical activity of neurons enables the causal assessment of their contributions to brain functions. Red light penetrates deeper into tissue than other visible wavelengths. We present a red-shifted cruxhalorhodopsin, Jaws, derived from Haloarcula (Halobacterium......) salinarum (strain Shark) and engineered to result in red light-induced photocurrents three times those of earlier silencers. Jaws exhibits robust inhibition of sensory-evoked neural activity in the cortex and results in strong light responses when used in retinas of retinitis pigmentosa model mice. We also...... demonstrate that Jaws can noninvasively mediate transcranial optical inhibition of neurons deep in the brains of awake mice. The noninvasive optogenetic inhibition opened up by Jaws enables a variety of important neuroscience experiments and offers a powerful general-use chloride pump for basic and applied...

  17. Hyperfine Structure and Isotope Shifts in Dy II

    Directory of Open Access Journals (Sweden)

    Dylan F. Del Papa

    2017-01-01

    Full Text Available Using fast-ion-beam laser-fluorescence spectroscopy (FIBLAS, we have measured the hyperfine structure (hfs of 14 levels and an additional four transitions in Dy II and the isotope shifts (IS of 12 transitions in the wavelength range of 422–460 nm. These are the first precision measurements of this kind in Dy II. Along with hfs and IS, new undocumented transitions were discovered within 3 GHz of the targeted transitions. These atomic data are essential for astrophysical studies of chemical abundances, allowing correction for saturation and the effects of blended lines. Lanthanide abundances are important in diffusion modeling of stellar interiors, and in the mechanisms and history of nucleosynthesis in the universe. Hfs and IS also play an important role in the classification of energy levels, and provide a benchmark for theoretical atomic structure calculations.

  18. Simultaneous multichannel wavelength multicasting and XOR logic gate multicasting for three DPSK signals based on four-wave mixing in quantum-dot semiconductor optical amplifier.

    Science.gov (United States)

    Qin, Jun; Lu, Guo-Wei; Sakamoto, Takahide; Akahane, Kouichi; Yamamoto, Naokatsu; Wang, Danshi; Wang, Cheng; Wang, Hongxiang; Zhang, Min; Kawanishi, Tetsuya; Ji, Yuefeng

    2014-12-01

    In this paper, we experimentally demonstrate simultaneous multichannel wavelength multicasting (MWM) and exclusive-OR logic gate multicasting (XOR-LGM) for three 10Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signals in quantum-dot semiconductor optical amplifier (QD-SOA) by exploiting the four-wave mixing (FWM) process. No additional pump is needed in the scheme. Through the interaction of the input three 10Gbps DPSK signal lights in QD-SOA, each channel is successfully multicasted to three wavelengths (1-to-3 for each), totally 3-to-9 MWM, and at the same time, three-output XOR-LGM is obtained at three different wavelengths. All the new generated channels are with a power penalty less than 1.2dB at a BER of 10(-9). Degenerate and non-degenerate FWM components are fully used in the experiment for data and logic multicasting.

  19. Manipulation of light wavelength at appropriate growth stage to enhance biomass productivity and fatty acid methyl ester yield using Chlorella vulgaris.

    Science.gov (United States)

    Kim, Dae Geun; Lee, Changsu; Park, Seung-Moon; Choi, Yoon-E

    2014-05-01

    LEDs light offer several advantages over the conventional lamps, thereby being considered as the optimal light sources for microalgal cultivation. In this study, various light-emitting diodes (LEDs) especially red and blue color with different light wavelengths were employed to explore the effects of light source on phototrophic cultivation of Chlorella vulgaris. Blue light illumination led to significantly increased cell size, whereas red light resulted in small-sized cell with active divisions. Based on the discovery of the effect of light wavelengths on microalgal biology, we then applied appropriate wavelength at different growth stages; blue light was illuminated first and then shifted to red light. By doing so, biomass and lipid productivity of C. vulgaris could be significantly increased, compared to that in the control. These results will shed light on a novel approach using LED light for microalgal biotechnology. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Wide range operation of regenerative optical parametric wavelength converter using ASE-degraded 43-Gb/s RZ-DPSK signals.

    Science.gov (United States)

    Gao, Mingyi; Kurumida, Junya; Namiki, Shu

    2011-11-07

    For sustainable growth of the Internet, wavelength-tunable optical regeneration is the key to scaling up high energy-efficiency dynamic optical path networks while keeping the flexibility of the network. Wavelength-tunable optical parametric regenerator (T-OPR) based on the gain saturation effect of parametric amplification in a highly nonlinear fiber is promising for noise reduction in phase-shift keying signals. In this paper, we experimentally evaluated the T-OPR performance for ASE-degraded 43-Gb/s RZ-DPSK signals over a 20-nm input wavelength range between 1527 nm and 1547 nm. As a result, we achieved improved power penalty performance for the regenerated idler with a proper pump power range.

  1. Cortisol shifts financial risk preferences.

    Science.gov (United States)

    Kandasamy, Narayanan; Hardy, Ben; Page, Lionel; Schaffner, Markus; Graggaber, Johann; Powlson, Andrew S; Fletcher, Paul C; Gurnell, Mark; Coates, John

    2014-03-04

    Risk taking is central to human activity. Consequently, it lies at the focal point of behavioral sciences such as neuroscience, economics, and finance. Many influential models from these sciences assume that financial risk preferences form a stable trait. Is this assumption justified and, if not, what causes the appetite for risk to fluctuate? We have previously found that traders experience a sustained increase in the stress hormone cortisol when the amount of uncertainty, in the form of market volatility, increases. Here we ask whether these elevated cortisol levels shift risk preferences. Using a double-blind, placebo-controlled, cross-over protocol we raised cortisol levels in volunteers over 8 d to the same extent previously observed in traders. We then tested for the utility and probability weighting functions underlying their risk taking and found that participants became more risk-averse. We also observed that the weighting of probabilities became more distorted among men relative to women. These results suggest that risk preferences are highly dynamic. Specifically, the stress response calibrates risk taking to our circumstances, reducing it in times of prolonged uncertainty, such as a financial crisis. Physiology-induced shifts in risk preferences may thus be an underappreciated cause of market instability.

  2. Cortisol shifts financial risk preferences

    Science.gov (United States)

    Kandasamy, Narayanan; Hardy, Ben; Page, Lionel; Schaffner, Markus; Graggaber, Johann; Powlson, Andrew S.; Fletcher, Paul C.; Gurnell, Mark; Coates, John

    2014-01-01

    Risk taking is central to human activity. Consequently, it lies at the focal point of behavioral sciences such as neuroscience, economics, and finance. Many influential models from these sciences assume that financial risk preferences form a stable trait. Is this assumption justified and, if not, what causes the appetite for risk to fluctuate? We have previously found that traders experience a sustained increase in the stress hormone cortisol when the amount of uncertainty, in the form of market volatility, increases. Here we ask whether these elevated cortisol levels shift risk preferences. Using a double-blind, placebo-controlled, cross-over protocol we raised cortisol levels in volunteers over 8 d to the same extent previously observed in traders. We then tested for the utility and probability weighting functions underlying their risk taking and found that participants became more risk-averse. We also observed that the weighting of probabilities became more distorted among men relative to women. These results suggest that risk preferences are highly dynamic. Specifically, the stress response calibrates risk taking to our circumstances, reducing it in times of prolonged uncertainty, such as a financial crisis. Physiology-induced shifts in risk preferences may thus be an underappreciated cause of market instability. PMID:24550472

  3. Proposal for Research and Development of a Hadron Calorimeter for High Magnetic Fields

    CERN Multimedia

    2002-01-01

    RD43 : We intend to pursue the R\\&D necessary to demonstrate that a Cu-scintillator hadron calorimeter can operate reliably and well at the LHC at large pseudorapidities (\\mid $\\eta$\\mid~$\\leq$~2.6) and in a high magnetic field (4~T). The chosen technique consists of embedding a wavelength shifting (WLS) fibre in a scintillator plate in the form of a $\\sigma$. A clear fibre, spliced on to the WLS fibre, transports the shifted light to a photodetector. This technique was chosen by the SDC Collaboration for their electromagnetic and hadronic calorimetry. R\\&D efforts will concentrate on radiation tolerant scintillator/WLS combinations, transducers that can provide gain and operate in high magnetic fields, the effect on the performance of dead material (e.g. coil of~$\\leq$~1 $\\lambda $) placed after 5-7 $\\lambda $, the effect on performance of a high resolution electromagnetic calorimeter, the design of a hermetic mechanical structure, the issues of calibration and monitoring.

  4. Organic wavelength selective mirrors for luminescent solar concentrators

    NARCIS (Netherlands)

    Verbunt, P.P.C.; Debije, M.G.; Broer, D.J.; Bastiaansen, C.W.M.; Boer, de D.K.G.; Wehrspohn, R.; Gombert, A.

    2012-01-01

    Organic polymeric chiral nematic liquid crystalline (cholesteric) wavelength selective mirrors can increase the efficiency of luminescent solar concentrators (LSCs) when they are illuminated with direct sunlight normal to the device. However, due to the angular dependence of the reflection band, at

  5. [Wavelength Selection in Hemolytic Evaluation Systems with Spectrophotometry Detection].

    Science.gov (United States)

    Zhang, Hong; Su, Baochang; Ye, Xunda; Luo, Man

    2016-04-01

    Spectrophotometry is a simple hemolytic evaluation method commonly used in new drugs,biomedical materials and blood products.It is for the quantitative analysis of the characteristic absorption peaks of hemoglobin.Therefore,it is essential to select the correct detection wavelength when the evaluation system has influences on the conformation of hemoglobin.Based on the study of changes in the characteristic peaks over time of the hemolysis supernatant in four systems,namely,cell culture medium,phosphate buffered saline(PBS),physiological saline and banked blood preservation solution,using continuous wavelength scanning,the selections of detection wavelength were proposed as follows.In the cell culture medium system,the wavelength of 415 nm should be selected within 4h;,near 408 nm should be selected within 4~72h.In PBS system,within 4h,541 nm,577nm or 415 nm should be selected;4~72h,541 nm,577nm or near 406 nm should be selected.In physiological saline system,within 4h,414 nm should be selected;4~72h,near 405 nm should be selected;within 12 h,541nm or 577 nm could also be selected.In banked blood preservation solution system,within 72 h,415nm,540 nm or 576 nm should be selected.

  6. Metallic nano-cavity lasers at near infrared wavelengths

    NARCIS (Netherlands)

    Hill, M.T.; Stockman, M.I.

    2009-01-01

    There has been considerable interest in nano-cavity lasers, both from a scientific perspective for investigating fundamental properties of lasers and cavities, and also to produce smaller and better lasers for low-power applications. Light confinement on a wavelength scale has been reported in

  7. Pilot tones in WDM networks with wavelength converters

    DEFF Research Database (Denmark)

    Kloch, Allan; Mikkelsen, Benny; Stubkjær, Kristian

    1997-01-01

    Here we investigate the transmission of a pilot tone through an interferometric wavelength converter (IWC) in conjunction with a 2.5 Gbit/s experiment. The pilot tone is added by sinusoidal modulation of the bias current to the signal laser. After the IWC (Michelson interferometer) the converted...

  8. Wavelength selection method with standard deviation: application to pulse oximetry.

    Science.gov (United States)

    Vazquez-Jaccaud, Camille; Paez, Gonzalo; Strojnik, Marija

    2011-07-01

    Near-infrared spectroscopy provides useful biological information after the radiation has penetrated through the tissue, within the therapeutic window. One of the significant shortcomings of the current applications of spectroscopic techniques to a live subject is that the subject may be uncooperative and the sample undergoes significant temporal variations, due to his health status that, from radiometric point of view, introduce measurement noise. We describe a novel wavelength selection method for monitoring, based on a standard deviation map, that allows low-noise sensitivity. It may be used with spectral transillumination, transmission, or reflection signals, including those corrupted by noise and unavoidable temporal effects. We apply it to the selection of two wavelengths for the case of pulse oximetry. Using spectroscopic data, we generate a map of standard deviation that we propose as a figure-of-merit in the presence of the noise introduced by the living subject. Even in the presence of diverse sources of noise, we identify four wavelength domains with standard deviation, minimally sensitive to temporal noise, and two wavelengths domains with low sensitivity to temporal noise.

  9. Single-wavelength functional photoacoustic microscopy in biological tissue

    OpenAIRE

    Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

    2011-01-01

    Recently, we developed a reflection-mode relaxation photoacoustic microscope, based on saturation intensity, to measure picosecond relaxation times using a nanosecond laser. Here, using the different relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, the oxygen saturation was quantified in vivo with single-wavelength photoacoustic microscopy. All previous functional photoacoustic microscopy measurements required ima...

  10. POF based glucose sensor incorporating grating wavelength filters

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Aasmul, Søren; Bang, Ole

    2014-01-01

    AND RESEARCH IN POLYMER OPTICAL DEVICES; TRIPOD. Within the domain of TRIPOD, research is conducted on "Plastic Optical Fiber based Glucose Sensors Incorporating Grating Wavelength Filters". Research will be focused to optimized fiber tips for better coupling efficiency, reducing the response time of sensor...

  11. Compact titanium dioxide waveguides with high nonlinearity at telecommunication wavelengths

    DEFF Research Database (Denmark)

    Guan, Xiaowei; Hu, Hao; Oxenløwe, Leif Katsuo

    2018-01-01

    .43 mu m(2)) and a low loss (5.4 +/- 1 dB/cm) at telecommunication wavelengths around 1550 nm have been fabricated and measured. A microring resonator having a 50 mu m radius has been measured to have a loaded quality factor of 53500. Four-wave mixing experiments reveal a nonlinear parameter...

  12. Agility of Felix Regarding Wavelength and Micropulse Shape

    NARCIS (Netherlands)

    Bakker, R. J.; van der Geer, C. A. J.; Jaroszynski, D. A.; van der Meer, A. F. G.; Oepts, D.; van Amersfoort, P. W.; Anderegg, V.; van Son, P. C.

    1993-01-01

    The user-facility FELIX employs two FELs together covering the spectral range from 6.5 to 110 mum. Adjustment of the undulator strength permits wavelength tuning over a factor of two within two minutes while continuously providing several kilowatts of output power. As FELIX combines short electron

  13. Nonlinear propagation of short wavelength drift-Alfven waves

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two-dim...

  14. Enabling Searches on Wavelengths in a Hyperspectral Indices Database

    Science.gov (United States)

    Piñuela, F.; Cerra, D.; Müller, R.

    2017-10-01

    Spectral indices derived from hyperspectral reflectance measurements are powerful tools to estimate physical parameters in a non-destructive and precise way for several fields of applications, among others vegetation health analysis, coastal and deep water constituents, geology, and atmosphere composition. In the last years, several micro-hyperspectral sensors have appeared, with both full-frame and push-broom acquisition technologies, while in the near future several hyperspectral spaceborne missions are planned to be launched. This is fostering the use of hyperspectral data in basic and applied research causing a large number of spectral indices to be defined and used in various applications. Ad hoc search engines are therefore needed to retrieve the most appropriate indices for a given application. In traditional systems, query input parameters are limited to alphanumeric strings, while characteristics such as spectral range/ bandwidth are not used in any existing search engine. Such information would be relevant, as it enables an inverse type of search: given the spectral capabilities of a given sensor or a specific spectral band, find all indices which can be derived from it. This paper describes a tool which enables a search as described above, by using the central wavelength or spectral range used by a given index as a search parameter. This offers the ability to manage numeric wavelength ranges in order to select indices which work at best in a given set of wavelengths or wavelength ranges.

  15. Long-Wavelength Phonon Scattering in Nonpolar Semiconductors

    DEFF Research Database (Denmark)

    Lawætz, Peter

    1969-01-01

    The long-wavelength acoustic- and optical-phonon scattering of carriers in nonpolar semiconductors is considered from a general point of view. The deformation-potential approximation is defined and it is shown that long-range electrostatic forces give a nontrivial correction to the scattering...... of the very-short-range nature of interactions in a covalent semiconductor....

  16. Wavelength-converted long-reach reconfigurable optical access network

    NARCIS (Netherlands)

    Tran, N.C.; Tangdiongga, E.; Koonen, A.M.J.

    2012-01-01

    Next generation optical access networks should not only increase the capacity but also be able to redistribute the capacity on the fly in order to manage more fluctuated traffic patterns. Wavelength reconfigurability is the instrument to enable such capability of network-wide bandwidth

  17. Vertical integration of dual wavelength index guided lasers

    NARCIS (Netherlands)

    Karouta, F.; Tan, H.H.; Jagadish, C.; Roy, van B.H.

    1999-01-01

    The vertical integration of two GaAs-based lasers operating at different wavelengths has been achieved with the use of re-growth technology. A V-channel substrate inner stripe structure was used for the bottom laser and a ridge waveguide for the top laser. Both lasers shared a common electrode and

  18. CO ICE PHOTODESORPTION: A WAVELENGTH-DEPENDENT STUDY

    International Nuclear Information System (INIS)

    Fayolle, Edith C.; Linnartz, Harold; Bertin, Mathieu; Romanzin, Claire; Michaut, Xavier; Fillion, Jean-Hugues; Oeberg, Karin I.

    2011-01-01

    UV-induced photodesorption of ice is a non-thermal evaporation process that can explain the presence of cold molecular gas in a range of interstellar regions. Information on the average UV photodesorption yield of astrophysically important ices exists for broadband UV lamp experiments. UV fields around low-mass pre-main-sequence stars, around shocks and in many other astrophysical environments are however often dominated by discrete atomic and molecular emission lines. It is therefore crucial to consider the wavelength dependence of photodesorption yields and mechanisms. In this work, for the first time, the wavelength-dependent photodesorption of pure CO ice is explored between 90 and 170 nm. The experiments are performed under ultra high vacuum conditions using tunable synchrotron radiation. Ice photodesorption is simultaneously probed by infrared absorption spectroscopy in reflection mode of the ice and by quadrupole mass spectrometry of the gas phase. The experimental results for CO reveal a strong wavelength dependence directly linked to the vibronic transition strengths of CO ice, implying that photodesorption is induced by electronic transition (DIET). The observed dependence on the ice absorption spectra implies relatively low photodesorption yields at 121.6 nm (Lyα), where CO barely absorbs, compared to the high yields found at wavelengths coinciding with transitions into the first electronic state of CO (A 1 Π at 150 nm); the CO photodesorption rates depend strongly on the UV profiles encountered in different star formation environments.

  19. Recent advances in long wavelength quantum dot lasers and amplifiers

    NARCIS (Netherlands)

    Nötzel, R.; Bente, E.A.J.M.; Smit, M.K.; Dorren, H.J.S.

    2009-01-01

    We demonstrate 1.55-µm InAs/InGaAsP/InP (100) quantum dot (QD) shallow and deep etched Fabry-Pérot and ring lasers, micro-ring lasers, mode-locked lasers, Butt-joint integrated lasers, polarization control of gain, and wavelength conversion in QD amplifiers.

  20. Individual differences in shift work tolerance

    NARCIS (Netherlands)

    Lammers-van der Holst, H.M.

    2016-01-01

    Shift work is a key feature of our contemporary 24/7 society, employing several successive work teams to sustain around-the-clock operations. However, numerous studies imply that frequently shifting the periods of sleep and wakefulness poses a serious threat to the shift worker’s physical, mental

  1. Shifting Cultivation : Promoting Innovative Policy and Development ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Shifting Cultivation : Promoting Innovative Policy and Development Options in the Eastern Himalayas. Shifting ... pressure and market forces. The idea is to share good policies and practices related to shifting cultivation and alternative options through regional exchange. ... Les chaînes de valeur comme leviers stratégiques.

  2. Long-wavelength photonic integrated circuits and avalanche photodetectors

    Science.gov (United States)

    Tsou, Yi-Jen D.; Zaytsev, Sergey; Pauchard, Alexandre; Hummel, Steve; Lo, Yu-Hwa

    2001-10-01

    Fast-growing internet traffic volume require high data communication bandwidth over longer distances. Access network bottlenecks put pressure on short-range (SR) telecommunication systems. To effectively address these datacom and telecom market needs, low-cost, high-speed laser modules at 1310 to 1550 nm wavelengths and avalanche photodetectors are required. The great success of GaAs 850nm VCSEls for Gb/s Ethernet has motivated efforts to extend VCSEL technology to longer wavelengths in the 1310 and 1550 nm regimes. However, the technological challenges associated with materials for long wavelength VCSELs are tremendous. Even with recent advances in this area, it is believed that significant additional development is necessary before long wavelength VCSELs that meet commercial specifications will be widely available. In addition, the more stringent OC192 and OC768 specifications for single-mode fiber (SMF) datacom may require more than just a long wavelength laser diode, VCSEL or not, to address numerous cost and performance issues. We believe that photonic integrated circuits (PICs), which compactly integrate surface-emitting lasers with additional active and passive optical components with extended functionality, will provide the best solutions to today's problems. Photonic integrated circuits have been investigated for more than a decade. However, they have produced limited commercial impact to date primarily because the highly complicated fabrication processes produce significant yield and device performance issues. In this presentation, we will discuss a new technology platform of InP-based PICs compatible with surface-emitting laser technology, as well as a high data rate externally modulated laser module. Avalanche photodetectors (APDs) are the key component in the receiver to achieve high data rate over long transmission distance because of their high sensitivity and large gain- bandwidth product. We have used wafer fusion technology to achieve In

  3. Accelerator physics and radiometric properties of superconducting wavelength shifters

    International Nuclear Information System (INIS)

    Scheer, Michael

    2008-01-01

    Subject of this thesis is the operation of wave-length shifters at electron storage rings and their use in radiometry. The basic aspects of the radiometry, the technical requirements, the influence of wave-length shifters on the storage ring, and results of first measurements are presented for a device installed at BESSY. Most of the calculations are carried out by the program WAVE, which has been developed within this thesis. WAVE allows to calculate the synchrotron radiation spectra of wavelength shifters within an relative uncertainty of 1/100000. The properties of wave-length shifters in terms of accelerator physics as well as a generating function for symplectic tracking calculations can also be calculated by WAVE. The later was implemented in the tracking code BETA to investigate the influence of insertion devices on the dynamic aperture and emittance of the storage ring. These studies led to the concept of alternating low- and high-beta-sections at BESSY-II, which allow to operate superconducting insertion devices without a significant distortion of the magnetic optics. To investigate the experimental aspects of the radiometry at wave-length shifters, a program based on the Monte-Carlo-code GEANT4 has been developed. It allows to simulate the radiometrical measurements and the absorption properties of detectors. With the developed codes first radiometrical measurements by the PTB have been analysed. A comparison of measurements and calculations show a reasonable agreement with deviations of about five percent in the spectral range of 40-60 keV behind a 1-mm-Cu filter. A better agreement was found between 20 keV and 80 keV without Cu filter. In this case the measured data agreed within a systematic uncertainty of two percent with the results of the calculations. (orig.)

  4. Tilt shift determinations with spatial-carrier phase-shift method in temporal phase-shift interferometry

    International Nuclear Information System (INIS)

    Liu, Qian; Wang, Yang; He, Jianguo; Ji, Fang; Wang, Baorui

    2014-01-01

    An algorithm is proposed to deal with tilt-shift errors in temporal phase-shift interferometry (PSI). In the algorithm, the tilt shifts are detected with the spatial-carrier phase-shift (SCPS) method and then the tilt shifts are applied as priori information to the least-squares fittings of phase retrieval. The algorithm combines the best features of the SCPS and the temporal PSI. The algorithm could be applied to interferograms of arbitrary aperture without data extrapolation for the Fourier transform is not involved. Simulations and experiments demonstrate the effectiveness of the algorithm. The statistics of simulation results show a satisfied accuracy in detecting tilt-shift errors. Comparisons of the measurements with and without environmental vibration show that the proposed algorithm could compensate tilt-shift errors and retrieve wavefront phase accurately. The algorithm provides an approach to retrieve wavefront phase for the temporal PSI in vibrating environment. (paper)

  5. Steady State Shift Damage Localization

    DEFF Research Database (Denmark)

    Sekjær, Claus; Bull, Thomas; Markvart, Morten Kusk

    2017-01-01

    The steady state shift damage localization (S3DL) method localizes structural deterioration, manifested as either a mass or stiffness perturbation, by interrogating the damage-induced change in the steady state vibration response with damage patterns cast from a theoretical model. Damage is, thus...... the required accuracy when examining complex structures, an extensive amount of degrees of freedom (DOF) must often be utilized. Since the interrogation matrix for each damage pattern depends on the size of the system matrices constituting the FE-model, the computational time quickly becomes of first......-order importance. The present paper investigates two sub-structuring approaches, in which the idea is to employ Craig-Bampton super-elements to reduce the amount of interrogation distributions while still providing an acceptable localization resolution. The first approach operates on a strict super-element level...

  6. Identical and shifted identical bands

    International Nuclear Information System (INIS)

    Dodder, R.S; Jones, E.F.; Hamilton, J.H.

    1997-01-01

    Spontaneous fission of 252 Cm was studied with 72 large Compton suppressed Ge detectors in Gamma sphere. New isotopes 160 Sm and 162 Gd were identified. Through X-ray-γ and γ-γ-γ) coincidence measurements, level energies were established to spins 14 + to 20 + in 152 , 154 156 60 Nd 92 94 96 , 156 , 158 , 160 62 Sm 94 , 96 , 98 , and 160 , 162 64 Gd 96 , 98 . These nuclei exhibit a remarkable variety of identical bands and bands where the energies and moments of inertia are shifted by the same constant amount for every spin state from 2 + to 12 + for various combinations of nuclei differing by 2n, 4n, 2p, 4p, and α

  7. Measurement and modeling of low-wavelength losses in silica fibers and their impact at communication Wavelengths

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Grüner-Nielsen, Lars; Rottwitt, Karsten

    2009-01-01

    Using the cutback technique, the attenuation of four different silica step-index fibers is measured in the very wide wavelength range of 190-1700 nm. The measured spectra are deconvolved into components describing Rayleigh scattering, infrared losses, Urbach edge, anomalous loss, and different...

  8. Local Analysis Approach for Short Wavelength Geopotential Variations

    Science.gov (United States)

    Bender, P. L.

    2009-12-01

    The value of global spherical harmonic analyses for determining 15 day to 30 day changes in the Earth's gravity field has been demonstrated extensively using data from the GRACE mission and previous missions. However, additional useful information appears to be obtainable from local analyses of the data. A number of such analyses have been carried out by various groups. In the energy approximation, the changes in the height of the satellite altitude geopotential can be determined from the post-fit changes in the satellite separation during individual one-revolution arcs of data from a GRACE-type pair of satellites in a given orbit. For a particular region, it is assumed that short wavelength spatial variations for the arcs crossing that region during a time T of interest would be used to determine corrections to the spherical harmonic results. The main issue in considering higher measurement accuracy in future missions is how much improvement in spatial resolution can be achieved. For this, the shortest wavelengths that can be determined are the most important. And, while the longer wavelength variations are affected by mass distribution changes over much of the globe, the shorter wavelength ones hopefully will be determined mainly by more local changes in the mass distribution. Future missions are expected to have much higher accuracy for measuring changes in the satellite separation than GRACE. However, how large an improvement in the derived results in hydrology will be achieved is still very much a matter of study, particularly because of the effects of uncertainty in the time variations in the atmospheric and oceanic mass distributions. To be specific, it will be assumed that improving the spatial resolution in continental regions away from the coastlines is the objective, and that the satellite altitude is in the range of roughly 290 to 360 km made possible for long missions by drag-free operation. The advantages of putting together the short wavelength

  9. Observation of Atom Wave Phase Shifts Induced by Van Der Waals Atom-Surface Interactions

    International Nuclear Information System (INIS)

    Perreault, John D.; Cronin, Alexander D.

    2005-01-01

    The development of nanotechnology and atom optics relies on understanding how atoms behave and interact with their environment. Isolated atoms can exhibit wavelike (coherent) behavior with a corresponding de Broglie wavelength and phase which can be affected by nearby surfaces. Here an atom interferometer is used to measure the phase shift of Na atom waves induced by the walls of a 50 nm wide cavity. To our knowledge this is the first direct measurement of the de Broglie wave phase shift caused by atom-surface interactions. The magnitude of the phase shift is in agreement with that predicted by Lifshitz theory for a nonretarded van der Waals interaction. This experiment also demonstrates that atom waves can retain their coherence even when atom-surface distances are as small as 10 nm

  10. Apparatus for measuring speed through the Doppler frequency shift of sound

    Science.gov (United States)

    Schier, Walter

    2011-04-01

    The Doppler frequency shift of sound apparatus is based on a one meter diameter rotary table with a "button" speaker at its outer edge. A semicircular waveguide encloses half the periphery and has a microphone pickup on its wall at the midpoint. The tangential speed of the button speaker can be determined two ways for comparison. One method calculates speed from the frequency shift of sound, the other uses the repeat sound pattern. Agreement to one percent is possible at speeds of about 25 mph. In the lab the microphone output is fed successively to pairs of students at ten computer stations. Students must also perform an exercise in their lab report that introduces them to the red shifted wavelengths of receding galaxies at determined distances from the earth thus introducing them to Hubble's law, the concept of the "Big Bang", and their estimate of the age of the universe.

  11. Liquid level and temperature sensing by using dual-wavelength fiber laser based on multimode interferometer and FBG in parallel

    Science.gov (United States)

    Sun, Chunran; Dong, Yue; Wang, Muguang; Jian, Shuisheng

    2018-03-01

    The detection of liquid level and temperature based on a fiber ring cavity laser sensing configuration is presented and demonstrated experimentally. The sensing head contains a fiber Bragg grating (FBG) and a single-mode-cladding-less-single-mode multimode interferometer, which also functions as wavelength-selective components of the fiber laser. When the liquid level or temperature is applied on the sensing head, the pass-band peaks of both multimode interference (MMI) filter and FBG filter vary and the two output wavelengths of the laser shift correspondingly. In the experiment, the corresponding sensitivities of the liquid level with four different refractive indices (RI) in the deep range from 0 mm to 40 mm are obtained and the sensitivity enhances with the RI of the liquid being measured. The maximum sensitivity of interferometer is 106.3 pm/mm with the RI of 1.391. For the temperature measurement, a sensitivity of 10.3 pm/°C and 13.8 pm/°C are achieved with the temperature ranging from 0 °C to 90 °C corresponding to the two lasing wavelengths selective by the MMI filter and FBG, respectively. In addition, the average RI sensitivity of 155.77 pm/mm/RIU is also obtained in the RI range of 1.333-1.391.

  12. Effect of Shift Work on Nocturia.

    Science.gov (United States)

    Kim, Jin Wook

    2016-01-01

    To identify the circadian sensitive component of nocturia by comparing nocturia in patients who voluntarily choose a disrupted circadian rhythm, that is, shift workers, with those who maintain normal day-night cycles. Between 2011 and 2013, a total of 1741 untreated patients, 1376 nonshift workers and 365 shift workers, were compared for nocturia indices based on frequency volume charts (FVCs). General linear model of 8-hour interval urine production and frequency were compared between FVCs of nonshift workers, FVCs of night-shift workers, and FVCs of day-shift workers. Nocturia frequency was increased in the night-shift workers (2.38 ± 1.44) compared with nonshift workers (2.18 ± 1.04) (P night-shift workers, 0.34 ± 0.13 for nonshift workers, P = .24), nocturnal bladder capacity index increased significantly (1.41 ± 1.06 for night-shift workers, 1.26 ± 0.92 for nonshift workers, P shift (P shift changes (P = .35). Patients in alternating work shifts showed increased nocturia, especially during their night shift. These changes tended to be more associated with decreased nocturnal bladder capacity than increased nocturnal polyuria. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Real life working shift assignment problem

    Science.gov (United States)

    Sze, San-Nah; Kwek, Yeek-Ling; Tiong, Wei-King; Chiew, Kang-Leng

    2017-07-01

    This study concerns about the working shift assignment in an outlet of Supermarket X in Eastern Mall, Kuching. The working shift assignment needs to be solved at least once in every month. Current approval process of working shifts is too troublesome and time-consuming. Furthermore, the management staff cannot have an overview of manpower and working shift schedule. Thus, the aim of this study is to develop working shift assignment simulation and propose a working shift assignment solution. The main objective for this study is to fulfill manpower demand at minimum operation cost. Besides, the day off and meal break policy should be fulfilled accordingly. Demand based heuristic is proposed to assign working shift and the quality of the solution is evaluated by using the real data.

  14. Dynamics and computation in functional shifts

    Science.gov (United States)

    Namikawa, Jun; Hashimoto, Takashi

    2004-07-01

    We introduce a new type of shift dynamics as an extended model of symbolic dynamics, and investigate the characteristics of shift spaces from the viewpoints of both dynamics and computation. This shift dynamics is called a functional shift, which is defined by a set of bi-infinite sequences of some functions on a set of symbols. To analyse the complexity of functional shifts, we measure them in terms of topological entropy, and locate their languages in the Chomsky hierarchy. Through this study, we argue that considering functional shifts from the viewpoints of both dynamics and computation gives us opposite results about the complexity of systems. We also describe a new class of shift spaces whose languages are not recursively enumerable.

  15. Rigorous Progress on Algorithms Based Routing and Wavelength Assignment in Trans-Egypt Network (TEGYNET) Management

    OpenAIRE

    Abd El–Naser A. Mohammed; Ahmed Nabih Zaki Rashed; Osama S. Fragallah; Mohamed G. El-Abyad

    2013-01-01

    In simple wavelength-division multiplexed (WDM) networks, a connection must be established along a route using a common wavelength on all of the links along the route. The introduction of wavelength converters into WDM cross connects increases the hardware cost and complexity. Given a set of connection requests, the routing and wavelength assignment problem involves finding a route (routing) and assigning a wavelength to each request. This paper has presented the WDM technology is being exten...

  16. Switchable multi-wavelength erbium-doped fiber ring laser based on a tapered in-line Mach–Zehnder interferometer

    Science.gov (United States)

    Zhou, Yuxin; Wang, Xin; Tang, Zijuan; Lou, Shuqin

    2018-05-01

    In this paper, a switchable multi-wavelength erbium-doped fiber ring laser based on a tapered in-line Mach–Zehnder interferometer is proposed. The in-line Mach–Zehnder interferometer is fabricated by splicing a large-core fiber between two segments of single mode fibers, in which the first splicing point is tapered and the second splicing point is connected directly. By carefully rotating the polarization controller, switchable single-, dual-, triple- and quad-wavelength lasing outputs can be obtained with a side mode suppression ratio higher than 50 dB. The maximal peak power difference of multi-wavelength lasing is 3.67 dB, demonstrating a good power equalization performance. Furthermore, the proposed laser is proven to be very stable at room temperature. The wavelength shifts and peak power fluctuations are less than 0.02 nm and 1.3 dB over half an hour. In addition, stable quintuple-wavelength lasing with a side mode suppression ratio higher than 50 dB can also be realized when the filter length is changed.

  17. GaAsSb/InGaAs type-II quantum wells for long-wavelength lasers on GaAs substrates

    International Nuclear Information System (INIS)

    Klem, J. F.; Blum, O.; Kurtz, S. R.; Fritz, I. J.; Choquette, K. D.

    2000-01-01

    We have investigated the properties of GaAsSb/InGaAs type-II bilayer quantum-well structures grown by molecular-beam epitaxy for use in long-wavelength lasers on GaAs substrates. Structures with layer strains and thicknesses designed to be thermodynamically stable against dislocation formation exhibit room-temperature photoluminescence at wavelengths as long as 1.43 μm. The photoluminescence emission wavelength is significantly affected by growth temperature and the sequence of layer growth (InGaAs/GaAsSb versus GaAsSb/InGaAs), suggesting that Sb and/or In segregation results in nonideal interfaces under certain growth conditions. At low-injection currents, double-heterostructure lasers with GaAsSb/InGaAs bilayer quantum-well active regions display electroluminescence at wavelengths comparable to those obtained in photoluminescence, but at higher currents the electroluminescence shifts to shorter wavelengths. Lasers have been obtained with threshold current densities of 120 A/cm2 at 1.17 μm, and 2.1 kA/cm2 at 1.21 μm. (c) 2000 American Vacuum Society

  18. Two-Copy Wavelength Conversion of an 80 Gbit/s Serial Data Signal Using Cross-Phase Modulation in a Silicon Nanowire and Detailed Pump-Probe Characterisation

    DEFF Research Database (Denmark)

    Ji, Hua; Cleary, C. S.; Dailey, J. M.

    2012-01-01

    We experimentally demonstrate 80 Gbit/s wavelength conversion to two copies by simultaneously extracting the blue- and red-shifted sidebands from XPM in a silicon nanowire. Bit error rates of 10-9 with only ~2 dB power penalty is achieved for both sidebands. Detailed pump-probe characterisation r...

  19. Multi-Wavelength Polarimetry of Isolated Neutron Stars

    Directory of Open Access Journals (Sweden)

    Roberto P. Mignani

    2018-03-01

    Full Text Available Isolated neutron stars are known to be endowed with extreme magnetic fields, whose maximum intensity ranges from 10 12 – 10 15 G, which permeates their magnetospheres. Their surrounding environment is also strongly magnetized, especially in the compact nebulae powered by the relativistic wind from young neutron stars. The radiation from isolated neutron stars and their surrounding nebulae is, thus, supposed to bring a strong polarization signature. Measuring the neutron star polarization brings important information about the properties of their magnetosphere and of their highly magnetized environment. Being the most numerous class of isolated neutron stars, polarization measurements have been traditionally carried out for radio pulsars, hence in the radio band. In this review, I summarize multi-wavelength linear polarization measurements obtained at wavelengths other than radio both for pulsars and other types of isolated neutron stars and outline future perspectives with the upcoming observing facilities.

  20. Cavity-enhanced resonant tunneling photodetector at telecommunication wavelengths

    International Nuclear Information System (INIS)

    Pfenning, Andreas; Hartmann, Fabian; Langer, Fabian; Höfling, Sven; Kamp, Martin; Worschech, Lukas

    2014-01-01

    An AlGaAs/GaAs double barrier resonant tunneling diode (RTD) with a nearby lattice-matched GaInNAs absorption layer was integrated into an optical cavity consisting of five and seven GaAs/AlAs layers to demonstrate cavity enhanced photodetection at the telecommunication wavelength 1.3 μm. The samples were grown by molecular beam epitaxy and RTD-mesas with ring-shaped contacts were fabricated. Electrical and optical properties were investigated at room temperature. The detector shows maximum photocurrent for the optical resonance at a wavelength of 1.29 μm. At resonance a high sensitivity of 3.1×10 4 A/W and a response up to several pA per photon at room temperature were found

  1. Automated dual-wavelength spectrophotometer optimized for phytochrome assay

    International Nuclear Information System (INIS)

    Pratt, L.H.; Wampler, J.E.; Rich, E.S. Jr.

    1985-01-01

    A microcomputer-controlled dual-wavelength spectrophotometer suitable for automated phytochrome assay is described. The optomechanical unit provides for sequential irradiation of the sample by the two measuring wavelengths with intervening dark intervals and for actinic irradiation to interconvert phytochrome between its two forms. Photomultiplier current is amplified, converted to a digital value and transferred into the computer using a custom-designed IEEE-488 bus interface. The microcomputer calculates mathematically both absorbance and absorbance difference values with dynamic correction for photomultiplier dark current. In addition, the computer controls the operating parameters of the spectrophotometer via a separate interface. These parameters include control of the durations of measuring and actinic irradiation intervals and their sequence. 14 references, 4 figures

  2. High accuracy wavelength calibration for a scanning visible spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Scotti, Filippo; Bell, Ronald E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2010-10-15

    Spectroscopic applications for plasma velocity measurements often require wavelength accuracies {<=}0.2 A. An automated calibration, which is stable over time and environmental conditions without the need to recalibrate after each grating movement, was developed for a scanning spectrometer to achieve high wavelength accuracy over the visible spectrum. This method fits all relevant spectrometer parameters using multiple calibration spectra. With a stepping-motor controlled sine drive, an accuracy of {approx}0.25 A has been demonstrated. With the addition of a high resolution (0.075 arc sec) optical encoder on the grating stage, greater precision ({approx}0.005 A) is possible, allowing absolute velocity measurements within {approx}0.3 km/s. This level of precision requires monitoring of atmospheric temperature and pressure and of grating bulk temperature to correct for changes in the refractive index of air and the groove density, respectively.

  3. Microscopic single-crystal refractometry as a function of wavelength

    International Nuclear Information System (INIS)

    DeLoach, L.D.

    1994-01-01

    The refractive indices of crystal fragments 50--200 μm in size can be measured for light wavelengths between 365 and 1100 nm with a spindle-stage refractometer. Established methods from optical crystallograpy are used to orient a crystal on the microscope spindle stage and then to match its refractive index to an immersion fluid. The refractive index of the fluid for the wavelength of light and matching temperature is determined by comparison of a reference crystal on a second spindle axis with the fluid under the match conditions. Investigations of new nonlinear-optical crystals admirably demonstrate the advantages of measuring the refractive index to ± 0.0004 in small single crystals

  4. Dual-Wavelength Sensitized Photopolymer for Holographic Data Storage

    Science.gov (United States)

    Tao, Shiquan; Zhao, Yuxia; Wan, Yuhong; Zhai, Qianli; Liu, Pengfei; Wang, Dayong; Wu, Feipeng

    2010-08-01

    Novel photopolymers for holographic storage were investigated by combining acrylate monomers and/or vinyl monomers as recording media and liquid epoxy resins plus an amine harder as binder. In order to improve the holographic performances of the material at blue-green wavelength band two novel dyes were used as sensitizer. The methods of evaluating the holographic performances of the material, including the shrinkage and noise characteristics, are described in detail. Preliminary experiments show that samples with optimized composite have good holographic performances, and it is possible to record dual-wavelength hologram simultaneously in this photopolymer by sharing the same optical system, thus the storage density and data rate can be doubly increased.

  5. Light Wavelength Correlation on the Effect of Hair Growth

    International Nuclear Information System (INIS)

    Wan Saffiey Wan Abdullah

    2010-01-01

    The use of laser light as a bio stimulator at certain wavelength is a new development in laser photonics and become an acceptable tool in medical therapy. It based on low power and low energy laser light. The effect of biological cells behaviour to low power laser light stimulates various studies in many areas such as for medical and cosmetic applications. This paper discusses some results of low power laser light that is used for stimulating the hair growth of skinned mouse by using an optically expanded low power laser light. The study indicates that the red light laser provide a significant growth of mouse hair with exposure duration of two hours daily for 24 consecutive days. Apart from that the green laser light is also used in this study; however result shows no significant influence to the growth of mouse hair in this light wavelength. (author)

  6. Excision of oral mucocele by different wavelength lasers

    Directory of Open Access Journals (Sweden)

    Umberto Romeo

    2013-01-01

    Full Text Available Background: Mucocele is a common benign neoplasm of oral soft tissues and the most common after fibroma. It generally occurs in the lower lip and its treatment includes excision of cyst and the responsible salivary gland, in order to prevent recurrences. Aims: To evaluate the capability of three different lasers in performing the excision of labial mucocele with two different techniques. Materials and Methods: In the presented cases, excision was performed using two different techniques (circumferential incision technique and mucosal preservation technique and three different laser wavelengths (Er,Cr:YSGG 2780 nm, diode 808 nm, and KTP 532 nm. Results: All the tested lasers, regardless of wavelength, showed many advantages (bloodless surgical field, no postoperative pain, relative speed, and easy execution. The most useful surgical technique depends on clinical features of the lesion. Conclusion: Tested lasers, with both techniques, are helpful in the management of labial mucocele.

  7. Approaches for a quantum memory at telecommunication wavelengths

    International Nuclear Information System (INIS)

    Lauritzen, Bjoern; Minar, Jiri; Riedmatten, Hugues de; Afzelius, Mikael; Gisin, Nicolas

    2011-01-01

    We report experimental storage and retrieval of weak coherent states of light at telecommunication wavelengths using erbium ions doped into a solid. We use two photon-echo-based quantum storage protocols. The first one is based on controlled reversible inhomogeneous broadening (CRIB). It allows the retrieval of the light on demand by controlling the collective atomic coherence with an external electric field, via the linear Stark effect. We study how atoms in the excited state affect the signal-to-noise ratio of the CRIB memory. Additionally we show how CRIB can be used to modify the temporal width of the retrieved light pulse. The second protocol is based on atomic frequency combs. Using this protocol we verify that the reversible mapping is phase preserving by performing an interference experiment with a local oscillator. These measurements are enabling steps toward solid-state quantum memories at telecommunication wavelengths. We also give an outlook on possible improvements.

  8. System and Method for Multi-Wavelength Optical Signal Detection

    Science.gov (United States)

    McGlone, Thomas D. (Inventor)

    2017-01-01

    The system and method for multi-wavelength optical signal detection enables the detection of optical signal levels significantly below those processed at the discrete circuit level by the use of mixed-signal processing methods implemented with integrated circuit technologies. The present invention is configured to detect and process small signals, which enables the reduction of the optical power required to stimulate detection networks, and lowers the required laser power to make specific measurements. The present invention provides an adaptation of active pixel networks combined with mixed-signal processing methods to provide an integer representation of the received signal as an output. The present invention also provides multi-wavelength laser detection circuits for use in various systems, such as a differential absorption light detection and ranging system.

  9. Optogalvanic wavelength calibration for laser monitoring of reactive atmospheric species

    Science.gov (United States)

    Webster, C. R.

    1982-01-01

    Laser-based techniques have been successfully employed for monitoring atmospheric species of importance to stratospheric ozone chemistry or tropospheric air quality control. When spectroscopic methods using tunable lasers are used, a simultaneously recorded reference spectrum is required for wavelength calibration. For stable species this is readily achieved by incorporating into the sensing instrument a reference cell containing the species to be monitored. However, when the species of interest is short-lived, this approach is unsuitable. It is proposed that wavelength calibration for short-lived species may be achieved by generating the species of interest in an electrical or RF discharge and using optogalvanic detection as a simple, sensitive, and reliable means of recording calibration spectra. The wide applicability of this method is emphasized. Ultraviolet, visible, or infrared lasers, either CW or pulsed, may be used in aircraft, balloon, or shuttle experiments for sensing atoms, molecules, radicals, or ions.

  10. Linear programming phase unwrapping for dual-wavelength digital holography.

    Science.gov (United States)

    Wang, Zhaomin; Jiao, Jiannan; Qu, Weijuan; Yang, Fang; Li, Hongru; Tian, Ailing; Asundi, Anand

    2017-01-20

    A linear programming phase unwrapping method in dual-wavelength digital holography is proposed and verified experimentally. The proposed method uses the square of height difference as a convergence standard and theoretically gives the boundary condition in a searching process. A simulation was performed by unwrapping step structures at different levels of Gaussian noise. As a result, our method is capable of recovering the discontinuities accurately. It is robust and straightforward. In the experiment, a microelectromechanical systems sample and a cylindrical lens were measured separately. The testing results were in good agreement with true values. Moreover, the proposed method is applicable not only in digital holography but also in other dual-wavelength interferometric techniques.

  11. Observation of Rayleigh - Taylor growth to short wavelengths on Nike

    International Nuclear Information System (INIS)

    Pawley, C.J.; Bodner, S.E.; Dahlburg, J.P.; Obenschain, S.P.; Schmitt, A.J.; Sethian, J.D.; Sullivan, C.A.; Gardner, J.H.; Aglitskiy, Y.; Chan, Y.; Lehecka, T.

    1999-01-01

    The uniform and smooth focal profile of the Nike KrF laser [S. Obenschain et al., Phys. Plasmas 3, 2098 (1996)] was used to ablatively accelerate 40 μm thick polystyrene planar targets with pulse shaping to minimize shock heating of the compressed material. The foils had imposed small-amplitude sinusoidal wave perturbations of 60, 30, 20, and 12.5 μm wavelength. The shortest wavelength is near the ablative stabilization cutoff for Rayleigh - Taylor growth. Modification of the saturated wave structure due to random laser imprint was observed. Excellent agreement was found between the two-dimensional simulations and experimental data for most cases where the laser imprint was not dominant. copyright 1999 American Institute of Physics

  12. Short wavelength limits of current shot noise suppression

    International Nuclear Information System (INIS)

    Nause, Ariel; Dyunin, Egor; Gover, Avraham

    2014-01-01

    Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect

  13. Short wavelength limits of current shot noise suppression

    Energy Technology Data Exchange (ETDEWEB)

    Nause, Ariel, E-mail: arielnau@post.tau.ac.il [Faculty of Exact Sciences, Department of Physics, Tel Aviv University, Tel Aviv (Israel); Dyunin, Egor; Gover, Avraham [Faculty of Engineering, Department of Physical Electronics, Tel Aviv University, Tel Aviv (Israel)

    2014-08-15

    Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect.

  14. Dual-wavelength laser transmission photoscanner for breast cancer detection

    International Nuclear Information System (INIS)

    Kaneko, M.; He, P.; Tanaka, H.; Takahashi, M.; Takai, M.; Baba, K.; Yamashita, Y.; Ohta, K.

    1989-01-01

    This paper reports on the prototype of a laser transmission photoscanner (LTPS) constructed and used for the detection of breast cancer and compared with x-ray mammography. LTPS has been improved to enable spectroanalysis and application in breast cancer screening. The new type is introduced. In order to obtain higher sensitivity, the output of lasers was increased in intensity. The signal integration time was increased 10-fold, and the width of the detector area was doubled. The gated operation of the detector enables the good throughput. Simultaneous scanning in the dual wavelengths of 630 and 830 nm makes it possible to differentiate hemoglobin (Hb) and oxyhemoglobin (HbO 2 ) in spectroanalysis by means of Lambert--Beer's law. Clinical application of dual-wavelength LTPS shows good correlation with pathology

  15. MULTI-WAVELENGTH AFTERGLOWS OF FAST RADIO BURSTS

    International Nuclear Information System (INIS)

    Yi, Shuang-Xi; Gao, He; Zhang, Bing

    2014-01-01

    The physical origin of fast radio bursts (FRBs) is unknown. Detecting electromagnetic counterparts to FRBs in other wavelengths is essential to measure their distances and to determine their physical origin. Assuming that at least some of them are of cosmological origin, we calculate their afterglow light curves in multiple wavelengths (X-rays, optical, and radio) by assuming a range of total kinetic energies and redshifts. We focus on forward shock emission, but also consider the possibility that some of the FRBs might have bright reverse shock emission. In general, FRB afterglows are too faint to be detected by current detectors. Only if an FRB has a very low radiative efficiency in radio (hence, a very large kinetic energy), and when it is close enough to observe can its afterglow be detected in the optical and radio bands. We discuss observational strategies for detecting these faint afterglows using future telescopes such as Large Synoptic Survey Telescope and Expanded Very Large Array

  16. Multi-Wavelength Monitoring of GRS 1915+105

    Science.gov (United States)

    Bandyopadhyay, R.; Martini, P.; Gerard, E.; Charles, P. A.; Wagner, R. M.; Shrader, C.; Shahbaz, T.; Mirabel, I. F.

    1997-01-01

    Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present here first results from a multi-wavelength campaign undertaken from July to September 1996. This study includes X-ray data from the RXTE All Sky Monitor and BATSE, two-frequency data from the Nancay radio telescope, and infrared photometry from the 1.8 m Perkins telescope at Lowell Observatory. The first long-term well-sampled IR light curve of GRS 1915+105 is presented herein and is consistent with the interpretation of this source as a long-period binary. We compare the various light curves, searching for correlations in the behaviour of the source at differing wavelengths and for possible periodicities.

  17. Laser-assisted decontamination—A wavelength dependent study

    Science.gov (United States)

    Nilaya, J. Padma; Raote, Pallavi; Kumar, Aniruddha; Biswas, Dhruba J.

    2008-09-01

    We present here the experimental results on cleaning of radioactive dielectric particulates, loosely deposited on stainless steel, by coherent light of 1064 nm wavelength and its three harmonics occurring at 532 nm, 355 nm and 266 nm, derived from an Nd-YAG laser. For the initial few exposures, the decontamination factor has been found to be highest when exposed to 1064 nm radiation. With increasing number of exposures, however, the radiation with reducing wavelength assumes a more important role as a cleaning agent. The observation of almost no cleaning with 1064 nm and much reduced cleaning with its harmonics when the contamination is deposited on a transparent substrate confirms the dominant role played by metal substrate towards expelling the loose particulates from its surface.

  18. The sub-wavelength imaging performance of disordered wire media

    International Nuclear Information System (INIS)

    Powell, David A.

    2008-01-01

    An analysis of the sub-wavelength imaging performance of disordered thin wire media is undertaken, in order to understand how its performance may be affected by manufacturing errors. The structure is found to be extremely robust to disorder which keeps the wires parallel. Variation in the orientation of the wires and their longitudinal position causes more significant degradation in the image quality, which is quantified numerically

  19. Dual wavelength operation in diode-end-pumped hybrid vanadate ...

    Indian Academy of Sciences (India)

    Dual wavelength operation at 1062.8 nm and 1064.1 nm in a diode-pumped hybrid laser comprising of Nd3+-doped birefringent YVO4 and GdVO4 crystals is demon-strated. A detailed characterization of the laser is performed under CW and pulsed operation. Under Q-switching, 4 W of average power at 5 kHz repetition ...

  20. Properties of Sub-wavelength Resonances in Metamaterial Cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Clausen, N.C.J.; Pedersen, R.R.

    2008-01-01

    The analytical solution for the canonical configuration with electric line source illumination of concentric metamaterial cylinders is employed to study the properties of the observed sub-wavelength resonances. The near- and far-field distributions, the frequency and geometry bandwidths, and the ......, and the line source impedance are investigated for varying electromagnetic and geometrical parameters. The results of this study are of importance for metamaterial-based miniaturization of antennas....

  1. Wavelength-independent all-fiber mode converters.

    Science.gov (United States)

    Lai, K; Leon-Saval, S G; Witkowska, A; Wadsworth, W J; Birks, T A

    2007-02-15

    We have used two different photonic crystal fiber (PCF) techniques to make all-fiber mode converters. An LP(01) to LP(11) mode converter was made by the ferrule technique on a drawing tower, and an LP(01) to LP(02) mode converter was made by controlled hole inflation of an existing PCF on a tapering rig. Both devices rely on adiabatic propagation rather than resonant coupling; so high extinction was achieved across a wide wavelength range.

  2. Non-occupational physical activity levels of shift workers compared with non-shift workers

    Science.gov (United States)

    Loef, Bette; Hulsegge, Gerben; Wendel-Vos, G C Wanda; Verschuren, W M Monique; Bakker, Marije F; van der Beek, Allard J; Proper, Karin I

    2017-01-01

    Objectives Lack of physical activity (PA) has been hypothesised as an underlying mechanism in the adverse health effects of shift work. Therefore, our aim was to compare non-occupational PA levels between shift workers and non-shift workers. Furthermore, exposure–response relationships for frequency of night shifts and years of shift work regarding non-occupational PA levels were studied. Methods Data of 5980 non-shift workers and 532 shift workers from the European Prospective Investigation into Cancer and Nutrition-Netherlands (EPIC-NL) were used in these cross-sectional analyses. Time spent (hours/week) in different PA types (walking/cycling/exercise/chores) and intensities (moderate/vigorous) were calculated based on self-reported PA. Furthermore, sports were operationalised as: playing sports (no/yes), individual versus non-individual sports, and non-vigorous-intensity versus vigorous-intensity sports. PA levels were compared between shift workers and non-shift workers using Generalized Estimating Equations and logistic regression. Results Shift workers reported spending more time walking than non-shift workers (B=2.3 (95% CI 1.2 to 3.4)), but shift work was not associated with other PA types and any of the sports activities. Shift workers who worked 1–4 night shifts/month (B=2.4 (95% CI 0.6 to 4.3)) and ≥5 night shifts/month (B=3.7 (95% CI 1.8 to 5.6)) spent more time walking than non-shift workers. No exposure–response relationships were found between years of shift work and PA levels. Conclusions Shift workers spent more time walking than non-shift workers, but we observed no differences in other non-occupational PA levels. To better understand if and how PA plays a role in the negative health consequences of shift work, our findings need to be confirmed in future studies. PMID:27872151

  3. Free-space wavelength-multiplexed optical scanner demonstration.

    Science.gov (United States)

    Yaqoob, Zahid; Riza, Nabeel A

    2002-09-10

    Experimental demonstration of a no-moving-parts free-space wavelength-multiplexed optical scanner (W-MOS) is presented. With fast tunable lasers or optical filters and planar wavelength dispersive elements such as diffraction gratings, this microsecond-speed scanner enables large several-centimeter apertures for subdegree angular scans. The proposed W-MOS design incorporates a unique optical amplifier and variable optical attenuator combination that enables the calibration and modulation of the scanner response, leading to any desired scanned laser beam power shaping. The experimental setup uses a tunable laser centered at 1560 nm and a 600-grooves/mm blazed reflection grating to accomplish an angular scan of 12.92 degrees as the source is tuned over an 80-nm bandwidth. The values for calculated maximum optical beam divergance, required wavelength resolution, beam-pointing accuracy, and measured scanner insertion loss are 1.076 mrad, 0.172 nm, 0.06 mrad, and 4.88 dB, respectively.

  4. Long wavelength limit of evolution of nonlinear cosmological perturbations

    International Nuclear Information System (INIS)

    Hamazaki, Takashi

    2008-01-01

    In the general matter composition where the multiple scalar fields and the multiple perfect fluids coexist, in the leading order of the gradient expansion, we construct all of the solutions of the nonlinear evolutions of the locally homogeneous universe. From the momentum constraint, we derive the constraints which the solution constants of the locally homogeneous universe must satisfy. We construct the gauge invariant perturbation variables in the arbitrarily higher order nonlinear cosmological perturbation theory around the spatially flat Friedmann-Robertson-Walker universe. We construct the nonlinear long wavelength limit formula representing the long wavelength limit of the evolution of the nonlinear gauge invariant perturbation variables in terms of perturbations of the evolutions of the locally homogeneous universe. By using the long wavelength limit formula, we investigate the evolution of nonlinear cosmological perturbations in the universe dominated by the multiple slow rolling scalar fields with an arbitrary potential. The τ function and the N potential introduced in this paper make it possible to write the evolution of the multiple slow rolling scalar fields with an arbitrary interaction potential and the arbitrarily higher order nonlinear Bardeen parameter at the end of the slow rolling phase analytically. It is shown that the nonlinear parameters such as f NL and g NL are suppressed by the slow rolling expansion parameters.

  5. New preemptive scheduling for OBS networks considering cascaded wavelength conversion

    Science.gov (United States)

    Gao, Xingbo; Bassiouni, Mostafa A.; Li, Guifang

    2009-05-01

    In this paper we introduce a new preemptive scheduling technique for next generation optical burst-switched networks considering the impact of cascaded wavelength conversions. It has been shown that when optical bursts are transmitted all optically from source to destination, each wavelength conversion performed along the lightpath may cause certain signal-to-noise deterioration. If the distortion of the signal quality becomes significant enough, the receiver would not be able to recover the original data. Accordingly, subject to this practical impediment, we improve a recently proposed fair channel scheduling algorithm to deal with the fairness problem and aim at burst loss reduction simultaneously in optical burst switching. In our scheme, the dynamic priority associated with each burst is based on a constraint threshold and the number of already conducted wavelength conversions among other factors for this burst. When contention occurs, a new arriving superior burst may preempt another scheduled one according to their priorities. Extensive simulation results have shown that the proposed scheme further improves fairness and achieves burst loss reduction as well.

  6. Effective long wavelength scalar dynamics in de Sitter

    Energy Technology Data Exchange (ETDEWEB)

    Moss, Ian; Rigopoulos, Gerasimos, E-mail: ian.moss@newcastle.ac.uk, E-mail: gerasimos.rigopoulos@ncl.ac.uk [School of Mathematics and Statistics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU U.K. (United Kingdom)

    2017-05-01

    We discuss the effective infrared theory governing a light scalar's long wavelength dynamics in de Sitter spacetime. We show how the separation of scales around the physical curvature radius k / a ∼ H can be performed consistently with a window function and how short wavelengths can be integrated out in the Schwinger-Keldysh path integral formalism. At leading order, and for time scales Δ t >> H {sup −1}, this results in the well-known Starobinsky stochastic evolution. However, our approach allows for the computation of quantum UV corrections, generating an effective potential on which the stochastic dynamics takes place. The long wavelength stochastic dynamical equations are now second order in time, incorporating temporal scales Δ t ∼ H {sup −1} and resulting in a Kramers equation for the probability distribution—more precisely the Wigner function—in contrast to the more usual Fokker-Planck equation. This feature allows us to non-perturbatively evaluate, within the stochastic formalism, not only expectation values of field correlators, but also the stress-energy tensor of φ.

  7. Research with high-power short-wavelength lasers

    International Nuclear Information System (INIS)

    Holzrichter, J.F.; Campbell, E.M.; Lindl, J.D.; Storm, E.

    1985-01-01

    Three important high-temperature, high-density experiments were conducted recently using the 10-TW, short-wavelength Novette laser system at the Lawrence Livermore National Laboratory. These experiments demonstrated successful solutions to problems that arose during previous experiments with long wavelength lasers (lambda greater than or equal to 1μm) in which inertial confinement fusion (ICF), x-ray laser, and other high-temperature physics concepts were being tested. The demonstrations were: (1) large-scale plasmas (typical dimensions of up to 1000 laser wavelengths) were produced in which potentially deleterious laser-plasma instabilities were collisionally damped. (2) Deuterium-tritium fuel was imploded to a density of 20 g/cm 3 and a pressure of 10 10 atm. (3) A 700-fold amplification of soft x rays by stimulated emission at 206 and 209 A (62 eV) from Se +24 ions was observed in a laser-generated plasma. Isoelectronic scaling to 155 A (87 eV) in Y +29 was also demonstrated

  8. Photoacoustic imaging at 1064nm wavelength with exogenous contrast agents

    Science.gov (United States)

    Upputuri, Paul Kumar; Jiang, Yuyan; Pu, Kanyi; Pramanik, Manojit

    2018-02-01

    Photoacoustic (PA) imaging is a promising imaging modality for both preclinical research and clinical practices. Laser wavelengths in the first near infrared window (NIR-I, 650-950 nm) have been widely used for photoacoustic imaging. As compared with NIR-I window, scattering of photons by biological tissues is largely reduced in the second NIR (NIR-II) window, leading to enhanced imaging fidelity. However, the lack of biocompatible NIR-II absorbing exogenous agents prevented the use of this window for in vivo imaging. In recent years, few studies have been reported on photoacoustic imaging in NIR-II window using exogenous contrast agents. In this work, we discuss the recent work on PA imaging using 1064 nm wavelength, the fundamental of Nd:YAG laser, as an excitation wavelength. The PA imaging at 1064 nm is advantageous because of the low and homogeneous signal from tissue background, enabling high contrast in PA imaging when NIR-II absorbing contrast agents are employed.

  9. Swift Multi-wavelength Observing Campaigns: Strategies and Outcomes

    Science.gov (United States)

    Krimm, Hans A.

    2007-01-01

    The Swift gamma-ray burst explorer has been operating since December 2004 as both a gamma-ray burst (GRB) monitor and telescope and a multi-wavelength observatory, covering the energy range from V band and near UV to hard X rays above 150 keV. It is designed to rapidly repoint to observe newly discovered GRBs, and this maneuverability, combined with an easily changed observing program, allows Swift to also be an effective multiwavelength observatory for non-GRB targets, both as targets of opportunity and pre-planned multi-wavelength observing campaigns. Blazars are particularly attractive targets for coordinated campaigns with TeV experiments since many blazars are bright in both the hard X-ray and TeV energy ranges. Successful coordinated campaigns have included observations of 3C454.3 during its 2005 outburst. The latest Swift funding cycles allow for non- GRB related observations to be proposed. The Burst Alert Telescope on Swift also serves as a hard X-ray monitor with a public web page that includes light curves for over 400 X-ray sources and is used to alert the astronomical community about increased activity from both known and newly discovered sources. This presentation mill include Swift capabilities, strategies and policies for coordinated multi-wavelength observations as well as discussion of the potential outcomes of such campaigns.

  10. Wavelength and ambient luminance dependence of laser eye dazzle.

    Science.gov (United States)

    Williamson, Craig A; McLin, Leon N; Rickman, J Michael; Manka, Michael A; Garcia, Paul V; Kinerk, Wesley T; Smith, Peter A

    2017-10-10

    A series of experiments has been conducted to quantify the effects of laser wavelength and ambient luminance on the severity of laser eye dazzle experienced by human subjects. Eight laser wavelengths in the visible spectrum were used (458-647 nm) across a wide range of ambient luminance conditions (0.1-10,000  cd·m -2 ). Subjects were exposed to laser irradiance levels up to 600  μW·cm -2 and were asked to recognize the orientation of optotypes at varying eccentricities up to 31.6 deg of visual angle from the laser axis. More than 40,000 data points were collected from 14 subjects (ages 23-64), and these were consolidated into a series of obscuration angles for comparison to a theoretical model of laser eye dazzle. Scaling functions were derived to allow the model to predict the effects of laser dazzle on vision more accurately by including the effects of ambient luminance and laser wavelength. The updated model provides an improved match to observed laser eye dazzle effects across the full range of conditions assessed. The resulting model will find use in a variety of laser safety applications, including the estimation of maximum dazzle exposure and nominal ocular dazzle distance values.

  11. Mid-wavelength infrared unipolar nBp superlattice photodetector

    Science.gov (United States)

    Kazemi, Alireza; Myers, Stephen; Taghipour, Zahra; Mathews, Sen; Schuler-Sandy, Ted; Lee, Seunghyun; Cowan, Vincent M.; Garduno, Eli; Steenbergen, Elizabeth; Morath, Christian; Ariyawansa, Gamini; Scheihing, John; Krishna, Sanjay

    2018-01-01

    We report a Mid-Wavelength Infrared (MWIR) barrier photodetector based on the InAs/GaSb/AlSb type-II superlattice (T2SL) material system. The nBp design consists of a single unipolar barrier (InAs/AlSb SL) placed between a 4 μm thick p-doped absorber (InAs/GaSb SL) and an n-type contact layer (InAs/GaSb SL). At 80 K, the device exhibited a 50% cut-off wavelength of 5 μm, was fully turned-ON at zero bias and the measured QE was 50% (front side illumination with no AR coating) at 4.5 μm with a dark current density of 4.7 × 10-6 A/cm2 at Vb = 50 mV. At 150 K and Vb = 50 mV, the 50% cut-off wavelength increased to 5.3 μm, and the QE was 54% at 4.5 μm with a dark current of 5.0 × 10-4 A/cm2.

  12. SPLASH-SXDF Multi-wavelength Photometric Catalog

    Science.gov (United States)

    Mehta, Vihang; Scarlata, Claudia; Capak, Peter; Davidzon, Iary; Faisst, Andreas; Hsieh, Bau Ching; Ilbert, Olivier; Jarvis, Matt; Laigle, Clotilde; Phillips, John; Silverman, John; Strauss, Michael A.; Tanaka, Masayuki; Bowler, Rebecca; Coupon, Jean; Foucaud, Sébastien; Hemmati, Shoubaneh; Masters, Daniel; McCracken, Henry Joy; Mobasher, Bahram; Ouchi, Masami; Shibuya, Takatoshi; Wang, Wei-Hao

    2018-04-01

    We present a multi-wavelength catalog in the Subaru/XMM-Newton Deep Field (SXDF) as part of the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH). We include the newly acquired optical data from the Hyper-Suprime-Cam Subaru Strategic Program, accompanied by IRAC coverage from the SPLASH survey. All available optical and near-infrared data is homogenized and resampled on a common astrometric reference frame. Source detection is done using a multi-wavelength detection image including the u-band to recover the bluest objects. We measure multi-wavelength photometry and compute photometric redshifts as well as physical properties for ∼1.17 million objects over ∼4.2 deg2, with ∼800,000 objects in the 2.4 deg2 HSC-Ultra-Deep coverage. Using the available spectroscopic redshifts from various surveys over the range of 0 fraction of 3.2%. The SPLASH-SXDF catalog is a valuable, publicly available resource, perfectly suited for studying galaxies in the early universe and tracing their evolution through cosmic time.

  13. Linear response to long wavelength fluctuations using curvature simulations

    Energy Technology Data Exchange (ETDEWEB)

    Baldauf, Tobias; Zaldarriaga, Matias [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ (United States); Seljak, Uroš [Physics Department, Astronomy Department and Lawrence Berkeley National Laboratory, University of California, Berkeley, CA (United States); Senatore, Leonardo, E-mail: baldauf@ias.edu, E-mail: useljak@berkeley.edu, E-mail: senatore@stanford.edu, E-mail: matiasz@ias.edu [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA (United States)

    2016-09-01

    We study the local response to long wavelength fluctuations in cosmological N -body simulations, focusing on the matter and halo power spectra, halo abundance and non-linear transformations of the density field. The long wavelength mode is implemented using an effective curved cosmology and a mapping of time and distances. The method provides an alternative, more direct, way to measure the isotropic halo biases. Limiting ourselves to the linear case, we find generally good agreement between the biases obtained from the curvature method and the traditional power spectrum method at the level of a few percent. We also study the response of halo counts to changes in the variance of the field and find that the slope of the relation between the responses to density and variance differs from the naïve derivation assuming a universal mass function by approximately 8–20%. This has implications for measurements of the amplitude of local non-Gaussianity using scale dependent bias. We also analyze the halo power spectrum and halo-dark matter cross-spectrum response to long wavelength fluctuations and derive second order halo bias from it, as well as the super-sample variance contribution to the galaxy power spectrum covariance matrix.

  14. Fabrication of sub-wavelength photonic structures by nanoimprint lithography

    Energy Technology Data Exchange (ETDEWEB)

    Kontio, J.

    2013-11-01

    Nanoimprint lithography (NIL) is a novel but already a mature lithography technique. In this thesis it is applied to the fabrication of nanophotonic devices using its main advantage: the fast production of sub-micron features in high volume in a cost-effective way. In this thesis, fabrication methods for conical metal structures for plasmonic applications and sub-wavelength grating based broad-band mirrors are presented. Conical metal structures, nanocones, with plasmonic properties are interesting because they enable concentrating the energy of light in very tight spots resulting in very high local intensities of electromagnetic energy. The nanocone formation process is studied with several metals. Enhanced second harmonic generation using gold nanocones is presented. Bridged-nanocones are used to enhance Raman scattering from a dye solution. The sub-wavelength grating mirror is an interesting structure for photonics because it is very simple to fabricate and its reflectivity can be extended to the far infrared wavelength range. It also has polarization dependent properties which are used in this thesis to stabilize the output beam of infrared semiconductor disk laser. NIL is shown to be useful a technique in the fabrication of nanophotonic devices in the novel and rapidly growing field of plasmonics and also in more traditional, but still developing, semiconductor laser applications (orig.)

  15. Shift work-related health problems in

    Directory of Open Access Journals (Sweden)

    S. Khavaji

    2010-04-01

    Full Text Available Background and aimsShift work is a major feature of working life that affects diverse aspects of human life. The main purposes of this study were to investigate shift work-related health problems and their risk factors among workers of "12-hour shift" schedule.MethodsThis cross-sectional study was carried out at 8 petrochemical industries in Asalooyeh area. Study population consisted of 1203 workers including 549 shift worker (46% and 654 day worker (54%. Data on personal details, shift schedule and adverse effects of shift work werecollected by anonymous questionnaire. Statistical analyses were performed using SPSS, version 11.5. The level of significance was set at 5%.ResultsAlthough, the results showed that health problems among shift workers was more prevalent than day workers, but the differences were just significant in gastrointestinal and musculoskeletal disorders (p<0.05. Multiple linear regressions indicated that in addition to shift working, other variants such as long work hours, type of employment, second job, number of children and job title were associated with health problems.ConclusionPrevalence rates of gastrointestinal and musculoskeletal problems among shift workers were significantly higher than that of day workers. Although, working in shift system was the main significant factor associated with the reported problems, but other demographic andwork variables were also found to have association.

  16. Shift work as an oxidative stressor

    Directory of Open Access Journals (Sweden)

    Pasalar Parvin

    2005-12-01

    Full Text Available Abstract Background Some medical disorders have higher prevalence in shift workers than others. This study was designed to evaluate the effect of night-shift-working on total plasma antioxidant capacity, with respect to the causative role of oxidative stress in induction of some of these disorders. Methods Two blood samples were taken from 44 workers with a rotational shift schedule, one after their day shift and one after their night shift. The total plasma antioxidant capacity of each worker was measured through the FRAP method. The impacts of age and weight were also assessed. Results The total plasma antioxidant capacity was measured in 44 shift-workers with a mean age of 36.57 years (SD: 10.18 and mean BMI of 26.06 (SD: 4.37 after their day and night shifts. The mean reduction of total plasma antioxidant capacity after the night shift was 105.8 μmol/L (SD: 146.39. Also, a significant correlation was shown between age and weight and total plasma antioxidant capacity. Age and weight were found to be inversely related to total plasma antioxidant capacity; as age and weight increased, the total plasma antioxidant capacity decreased. Conclusion Shift work can act as an oxidative stressor and may induce many medical disorders. Aging and obesity in shift workers makes them more sensitive to this hazardous effect.

  17. Empirical isotropic chemical shift surfaces

    International Nuclear Information System (INIS)

    Czinki, Eszter; Csaszar, Attila G.

    2007-01-01

    A list of proteins is given for which spatial structures, with a resolution better than 2.5 A, are known from entries in the Protein Data Bank (PDB) and isotropic chemical shift (ICS) values are known from the RefDB database related to the Biological Magnetic Resonance Bank (BMRB) database. The structures chosen provide, with unknown uncertainties, dihedral angles φ and ψ characterizing the backbone structure of the residues. The joint use of experimental ICSs of the same residues within the proteins, again with mostly unknown uncertainties, and ab initio ICS(φ,ψ) surfaces obtained for the model peptides For-(l-Ala) n -NH 2 , with n = 1, 3, and 5, resulted in so-called empirical ICS(φ,ψ) surfaces for all major nuclei of the 20 naturally occurring α-amino acids. Out of the many empirical surfaces determined, it is the 13C α ICS(φ,ψ) surface which seems to be most promising for identifying major secondary structure types, α-helix, β-strand, left-handed helix (α D ), and polyproline-II. Detailed tests suggest that Ala is a good model for many naturally occurring α-amino acids. Two-dimensional empirical 13C α - 1 H α ICS(φ,ψ) correlation plots, obtained so far only from computations on small peptide models, suggest the utility of the experimental information contained therein and thus they should provide useful constraints for structure determinations of proteins

  18. Red Shifts and Existing Speculations

    Science.gov (United States)

    Aisenberg, Sol

    2009-03-01

    There are many current flaws, mysteries, and errors in the standard model of the universe - all based upon speculative interpretation of many excellent and verified observations. The most serious cause of some errors is the speculation about the meaning of the redshifts observed in the 1930s by Hubble. He ascribed the redshifts as due to ``an apparent Doppler effect''. This led to speculation that the remote stars were receding, and the universe was expanding -- although without observational proof of the actual receding velocity of the stars. The age of the universe, based upon the Hubble constant is pure speculation because of lack of velocity demonstration. The belief in expansion, the big bang, and of inflation should be reexamined. Also, the redshift cannot always be used as a distance measure, particularly for photons from quasars containing massive black holes that can reduce photon energy through gravitational attraction. If the linear Hubble constant is extrapolated to the most remote super novae and beyond, it would eventually require that the corresponding photon energy go to zero or become negative -- according to Hubble linear relationship. This should require a reexamination of the meaning of the red shift and the speculative consequences and give a model with fewer mysteries.

  19. Core shift effect in blazars

    Science.gov (United States)

    Agarwal, A.; Mohan, P.; Gupta, Alok C.; Mangalam, A.; Volvach, A. E.; Aller, M. F.; Aller, H. D.; Gu, M. F.; Lähteenmäki, A.; Tornikoski, M.; Volvach, L. N.

    2017-07-01

    We studied the pc-scale core shift effect using radio light curves for three blazars, S5 0716+714, 3C 279 and BL Lacertae, which were monitored at five frequencies (ν) between 4.8 and 36.8 GHz using the University of Michigan Radio Astronomical Observatory (UMRAO), the Crimean Astrophysical Observatory (CrAO) and Metsähovi Radio Observatory for over 40 yr. Flares were Gaussian fitted to derive time delays between observed frequencies for each flare (Δt), peak amplitude (A) and their half width. Using A ∝ να, we infer α in the range of -16.67-2.41 and using Δ t ∝ ν ^{1/k_r}, we infer kr ∼ 1, employed in the context of equipartition between magnetic and kinetic energy density for parameter estimation. From the estimated core position offset (Ωrν) and the core radius (rcore), we infer that opacity model may not be valid in all cases. The mean magnetic field strengths at 1 pc (B1) and at the core (Bcore) are in agreement with previous estimates. We apply the magnetically arrested disc model to estimate black hole spins in the range of 0.15-0.9 for these blazars, indicating that the model is consistent with expected accretion mode in such sources. The power-law-shaped power spectral density has slopes -1.3 to -2.3 and is interpreted in terms of multiple shocks or magnetic instabilities.

  20. Study of the optical properties of the DF2000MA daylight film used in the XENON1T muon veto water tank

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Diego [Institut fuer Physik, Johannes Gutenberg-Universitaet Mainz (Germany)

    2016-07-01

    XENON1T is the 3rd stage of a series of experiments performed by the XENON collaboration for the direct detection of dark matter candidates, such as WIMPs. Its projected spin-independent WIMP-nucleon elastic scattering cross-section entails an improvement of two orders of magnitude with respect to Xenon100 and requires, for a fiducial mass of the detector of about 1 ton liquid xenon, a similar reduction in background. In order to minimize the neutron background induced by cosmic ray muons, the XENON1T TPC is placed in the center of a 750 m{sup 3} water tank acting as an active Cherenkov muon veto, the walls of which are clad with the high reflective DF2000MA foil by 3M. The improved setup and results of a dedicated study of the reflective properties of the foil is presented, as well as a measurement of its possible wavelength shifting (WLS) properties. The analysis yields a specular reflectance of ∼ 100% for wavelengths larger than 400 nm, while ∼ 90% of the incoming light with wavelengths smaller than 370 nm is absorbed by the foil. The emission spectra of the WLS are dependent on the absorbed wavelength and show Gaussian shapes, with highest intensities at mean values of ∼ 450 nm emission wavelength.

  1. All-optical logic gates and wavelength conversion via the injection locking of a Fabry-Perot semiconductor laser

    Science.gov (United States)

    Harvey, E.; Pochet, M.; Schmidt, J.; Locke, T.; Naderi, N.; Usechak, N. G.

    2013-03-01

    This work investigates the implementation of all-optical logic gates based on optical injection locking (OIL). All-optical inverting, NOR, and NAND gates are experimentally demonstrated using two distributed feedback (DFB) lasers, a multi-mode Fabry-Perot laser diode, and an optical band-pass filter. The DFB lasers are externally modulated to represent logic inputs into the cavity of the multi-mode Fabry-Perot slave laser. The input DFB (master) lasers' wavelengths are aligned with the longitudinal modes of the Fabry-Perot slave laser and their optical power is used to modulate the injection conditions in the Fabry-Perot slave laser. The optical band-pass filter is used to select a Fabry- Perot mode that is either suppressed or transmitted given the logic state of the injecting master laser signals. When the input signal(s) is (are) in the on state, injection locking, and thus the suppression of the non-injected Fabry-Perot modes, is induced, yielding a dynamic system that can be used to implement photonic logic functions. Additionally, all-optical photonic processing is achieved using the cavity-mode shift produced in the injected slave laser under external optical injection. The inverting logic case can also be used as a wavelength converter — a key component in advanced wavelength-division multiplexing networks. As a result of this experimental investigation, a more comprehensive understanding of the locking parameters involved in injecting multiple lasers into a multi-mode cavity and the logic transition time is achieved. The performance of optical logic computations and wavelength conversion has the potential for ultrafast operation, limited primarily by the photon decay rate in the slave laser.

  2. Matching the laser wavelength to the absorption properties of matrices increases the ion yield in UV-MALDI mass spectrometry.

    Science.gov (United States)

    Wiegelmann, Marcel; Soltwisch, Jens; Jaskolla, Thorsten W; Dreisewerd, Klaus

    2013-09-01

    A high analytical sensitivity in ultraviolet matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) is only achieved if the laser wavelength corresponds to a high optical absorption of the matrix. Laser fluence and the physicochemical properties of the compounds, e.g., the proton affinity, also influence analytical sensitivity significantly. In combination, these parameters determine the amount of material ejected per laser pulse and the ion yield, i.e., the fraction of ionized biomolecules. Here, we recorded peptide ion signal intensities as a function of these parameters. Three cinnamic acid matrices were investigated: α-cyano-4-hydroxycinnamic acid, α-cyano-4-chlorocinnamic acid, and α-cyano-2,4-difluorocinnamic acid. In addition, 2,5-dihydroxybenzoic acid was used in comparison experiments. Ion signal intensities "per laser shot" and integrated ion signal intensities were acquired over 900 consecutive laser pulses applied on distinct positions on the dried-droplet sample preparations. With respect to laser wavelength, the two standard MALDI wavelengths of 337/355 nm were investigated. Also, 305 or 320 nm was selected to account for the blue-shifted absorption profiles of the halogenated derivatives. Maximal peptide ion intensities were obtained if the laser wavelength fell within the peak of the absorption profile of the compound and for fluences two to three times the corresponding ion detection threshold. The results indicate ways for improving the analytical sensitivity in MALDI-MS, and in particular for MALDI-MS imaging applications where a limited amount of material is available per irradiated pixel.

  3. Modeling Multi-wavelength Stellar Astrometry. III. Determination of the Absolute Masses of Exoplanets and Their Host Stars

    Science.gov (United States)

    Coughlin, J. L.; López-Morales, Mercedes

    2012-05-01

    Astrometric measurements of stellar systems are becoming significantly more precise and common, with many ground- and space-based instruments and missions approaching 1 μas precision. We examine the multi-wavelength astrometric orbits of exoplanetary systems via both analytical formulae and numerical modeling. Exoplanets have a combination of reflected and thermally emitted light that causes the photocenter of the system to shift increasingly farther away from the host star with increasing wavelength. We find that, if observed at long enough wavelengths, the planet can dominate the astrometric motion of the system, and thus it is possible to directly measure the orbits of both the planet and star, and thus directly determine the physical masses of the star and planet, using multi-wavelength astrometry. In general, this technique works best for, though is certainly not limited to, systems that have large, high-mass stars and large, low-mass planets, which is a unique parameter space not covered by other exoplanet characterization techniques. Exoplanets that happen to transit their host star present unique cases where the physical radii of the planet and star can be directly determined via astrometry alone. Planetary albedos and day-night contrast ratios may also be probed via this technique due to the unique signature they impart on the observed astrometric orbits. We develop a tool to examine the prospects for near-term detection of this effect, and give examples of some exoplanets that appear to be good targets for detection in the K to N infrared observing bands, if the required precision can be achieved.

  4. MODELING MULTI-WAVELENGTH STELLAR ASTROMETRY. III. DETERMINATION OF THE ABSOLUTE MASSES OF EXOPLANETS AND THEIR HOST STARS

    International Nuclear Information System (INIS)

    Coughlin, J. L.; López-Morales, Mercedes

    2012-01-01

    Astrometric measurements of stellar systems are becoming significantly more precise and common, with many ground- and space-based instruments and missions approaching 1 μas precision. We examine the multi-wavelength astrometric orbits of exoplanetary systems via both analytical formulae and numerical modeling. Exoplanets have a combination of reflected and thermally emitted light that causes the photocenter of the system to shift increasingly farther away from the host star with increasing wavelength. We find that, if observed at long enough wavelengths, the planet can dominate the astrometric motion of the system, and thus it is possible to directly measure the orbits of both the planet and star, and thus directly determine the physical masses of the star and planet, using multi-wavelength astrometry. In general, this technique works best for, though is certainly not limited to, systems that have large, high-mass stars and large, low-mass planets, which is a unique parameter space not covered by other exoplanet characterization techniques. Exoplanets that happen to transit their host star present unique cases where the physical radii of the planet and star can be directly determined via astrometry alone. Planetary albedos and day-night contrast ratios may also be probed via this technique due to the unique signature they impart on the observed astrometric orbits. We develop a tool to examine the prospects for near-term detection of this effect, and give examples of some exoplanets that appear to be good targets for detection in the K to N infrared observing bands, if the required precision can be achieved.

  5. Cost effective shift schedules enhance utility operations

    International Nuclear Information System (INIS)

    Coleman, R.M.

    1995-01-01

    This article describes how new shift scheduling concepts can save utility operations millions of dollars every year and yet maintain safety and improve employee morale. The key to scheduling is to define and match the work load. This includes discretionary as well as daily, weekly, and yearly core work loads. In most power plants the overall work load (including maintenance, operations, materials handling, etc.) on day shift is greater than on other shifts, hence an unbalanced schedule would be appropriate

  6. Stochastic dynamical models for ecological regime shifts

    DEFF Research Database (Denmark)

    Møller, Jan Kloppenborg; Carstensen, Jacob; Madsen, Henrik

    the physical and biological knowledge of the system, and nonlinearities introduced here can generate regime shifts or enhance the probability of regime shifts in the case of stochastic models, typically characterized by a threshold value for the known driver. A simple model for light competition between...... definition and stability of regimes become less subtle. Ecological regime shifts and their modeling must be viewed in a probabilistic manner, particularly if such model results are to be used in ecosystem management....

  7. Time Zones, Shift Working and International Outsourcing

    OpenAIRE

    Matsuoka, Yuji; Fukushima, Marcelo

    2009-01-01

    We build a trade model with two identical countries located in different time zones and a monopolistically competitive sector of which production requires differentiated goods produced in two successive stages. We introduce shift working disutility and allow consumers to choose between day and night shifts. Shift working disutility raises the cost of night production and firms can reduce costs by “virtually” outsourcing foreign labor. We found that firms only outsource if relat...

  8. Night shift work and modifiable lifestyle factors.

    Science.gov (United States)

    Pepłońska, Beata; Burdelak, Weronika; Krysicka, Jolanta; Bukowska, Agnieszka; Marcinkiewicz, Andrzej; Sobala, Wojciech; Klimecka-Muszyńska, Dorota; Rybacki, Marcin

    2014-10-01

    Night shift work has been linked to some chronic diseases. Modification of lifestyle by night work may partially contribute to the development of these diseases, nevertheless, so far epidemiological evidence is limited. The aim of the study was to explore association between night shift work and lifestyle factors using data from a cross-sectional study among blue-collar workers employed in industrial plants in Łódź, Poland. The anonymous questionnaire was self-administered among 605 employees (236 women and 369 men, aged 35 or more) - 434 individuals currently working night shifts. Distribution of the selected lifestyle related factors such as smoking, alcohol drinking, physical activity, body mass index (BMI), number of main meals and the hour of the last meal was compared between current, former, and never night shift workers. Adjusted ORs or predicted means were calculated, as a measure of the associations between night shift work and lifestyle factors, with age, marital status and education included in the models as covariates. Recreational inactivity (defined here as less than one hour per week of recreational physical activity) was associated with current night shift work when compared to never night shift workers (OR = 2.43, 95% CI: 1.13-5.22) among men. Alcohol abstinence and later time of the last meal was associated with night shift work among women. Statistically significant positive relationship between night shift work duration and BMI was observed among men (p = 0.029). This study confirms previous studies reporting lower exercising among night shift workers and tendency to increase body weight. This finding provides important public health implication for the prevention of chronic diseases among night shift workers. Initiatives promoting physical activity addressed in particular to the night shift workers are recommended.

  9. Night shift work and modifiable lifestyle factors

    Directory of Open Access Journals (Sweden)

    Beata Pepłońska

    2014-10-01

    Full Text Available Objectives: Night shift work has been linked to some chronic diseases. Modification of lifestyle by night work may partially contribute to the development of these diseases, nevertheless, so far epidemiological evidence is limited. The aim of the study was to explore association between night shift work and lifestyle factors using data from a cross-sectional study among blue-collar workers employed in industrial plants in Łódź, Poland. Material and Methods: The anonymous questionnaire was self-administered among 605 employees (236 women and 369 men, aged 35 or more - 434 individuals currently wor­king night shifts. Distribution of the selected lifestyle related factors such as smoking, alcohol drinking, physical activity, body mass index (BMI, number of main meals and the hour of the last meal was compared between current, former, and never night shift workers. Adjusted ORs or predicted means were calculated, as a measure of the associations between night shift work and lifestyle factors, with age, marital status and education included in the models as covariates. Results: Recreational inactivity (defined here as less than one hour per week of recreational physical activity was associated with current night shift work when compared to never night shift workers (OR = 2.43, 95% CI: 1.13-5.22 among men. Alcohol abstinence and later time of the last meal was associated with night shift work among women. Statistically significant positive relationship between night shift work duration and BMI was observed among men (p = 0.029. Conclusions: This study confirms previous studies reporting lower exercising among night shift workers and tendency to increase body weight. This finding provides important public health implication for the prevention of chronic diseases among night shift workers. Initiatives promoting physical activity addressed in particular to the night shift workers are recommended.

  10. Examining paid sickness absence by shift workers.

    Science.gov (United States)

    Catano, V M; Bissonnette, A B

    2014-06-01

    Shift workers are at greater risk than day workers with respect to psychological and physical health, yet little research has linked shift work to increased sickness absence. To investigate the relationship between shift work and sickness absence while controlling for organizational and individual characteristics and shift work attributes that have confounded previous research. The study used archive data collected from three national surveys in Canada, each involving over 20000 employees and 6000 private-sector firms in 14 different occupational groups. The employees reported the number of paid sickness absence days in the past 12 months. Data were analysed using both chi-squared statistics and hierarchical regressions. Contrary to previous research, shift workers took less paid sickness absence than day workers. There were no differences in the length of the sickness absence between both groups or in sickness absence taken by female and male workers whether working days or shifts. Only job tenure, the presence of a union in the workplace and working rotating shifts predicted sickness absence in shift workers. The results were consistent across all three samples. In general, shift work does not seem to be linked to increased sickness absence. However, such associations may be true for specific industries. Male and female workers did not differ in the amount of sickness absence taken. Rotating shifts, regardless of industry, predicted sickness absence among shift workers. Consideration should be given to implementing scheduled time off between shift changes. © The Author 2014. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Gas transmission : a paradigm shift

    International Nuclear Information System (INIS)

    Cornelson, D.W.

    1997-01-01

    The evolution of energy markets in North America was discussed. The investment opportunities that are possible in a deregulated energy market, be it in production or in the generation of energy commodities, in the development of midstream infrastructure, or in the provision of energy services, were outlined. Deregulation of crude oil, natural gas and electricity has resulted in significant changes in the structure of energy markets and the way in which customers are served. One of the advantages of competition regarding power generation is that it has turned energy into a commodity which has resulted in greater customer choice and efficiency. As one example of midstream infrastructure development, the Alliance Pipeline project was described. This project was conceived as a means to enhance the value of western Canadian natural gas. The 1,900 mile pipeline will run from British Columbia, through Alberta into Chicago where it will interconnect with the North American gas transmission grid. The pipeline is an efficient means of transporting energy from Western Canada to North American markets, and Alliance, as a lowest cost transporter, will continue to put pressure on the traditional infrastructure to become even more competitive at the margin. As such, Alliance represents a paradigm shift in energy transportation, and serves as an excellent example of the type of investment opportunity that a deregulated market can provide. It was suggested that innovation and competition in a deregulated North American energy market will continue to increase. As electricity is deregulated, the energy market will respond more quickly to changes in supply and demand than it did in the past, in an effort to satisfy the needs of investors and customers. This will provide increased opportunities for restructuring and further competition

  12. Shifting currents: Progress, setbacks, and shifts in policy and practice

    Science.gov (United States)

    ,; Dunning, Charles; Robertson, Dale M.

    2016-01-01

    clean water future. More than a decade has passed since our first statewide WOW conversation and the report that captured recommendations from its participants: Waters of Wisconsin: The Future of Our Aquatic Ecosystems and Resources. Drawing from a diverse and growing set of stakeholders from across the state, the Wisconsin Academy initiated a new conversation in 2012 (known as WOW II) to assess progress in regard to our 2003 recommendations. We also sought to review the status of waters in Wisconsin today. The result of this renewed conversation is Shifting Currents: Progress, Setbacks, and Shifts in Policy and Practice. The new report assesses progress in brief, and explores in greater depth the continuing and emerging challenges to water quality, supply, and aquatic ecosystems in Wisconsin.In this report, we first review the context and frameworks for public decision-making about water and then examine some of the root causes—or “drivers”—and ecological stressors that underlie many of the symptoms we see in the form of pollution or ecosystem degradation in Wisconsin. This is followed by a summary of current water issues, many of which had been identified in the 2003 report and remain relevant today. We examine progress since 2003 but also setbacks, and discuss issues that we are likely to continue to face in the coming decades, including controlling agricultural runoff, mitigating climate change and grappling with its effects on the state’s waters, protecting groundwater from bacterial contamination and other pollutants, and preventing groundwater depletion. We also attempt to anticipate issues on the horizon. We offer a deeper look at some particular challenges, such as phosphorus pollution and groundwater contamination. We then consider the current decision-making framework and how it is shaping our capacity to respond to water challenges in Wisconsin. Finally, we offer recommendations and identify opportunities to safeguard Wisconsin’s waters in the

  13. Goos-Haenchen shift in complex crystals

    Energy Technology Data Exchange (ETDEWEB)

    Longhi, Stefano; Della Valle, Giuseppe; Staliunas, Kestutis [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Departament de Fisica i Enginyeria Nuclear, Instituci Catalana de Recerca i Estudis Avanats (ICREA), Universitat Politcnica de Catalunya, Colom 11, E-08222 Terrassa, Barcelona (Spain)

    2011-10-15

    The Goos-Haenchen (GH) effect for wave scattering from complex PT-symmetric periodic potentials (complex crystals) is theoretically investigated, with specific reference to optical GH shift in photonic crystal slabs with a sinusoidal periodic modulation of both real and imaginary parts of the dielectric constant. The analysis highlights some distinct and rather unique features as compared to the GH shift found in ordinary crystals. In particular, as opposed to GH shift in ordinary crystals, which is large at the band gap edges, in complex crystals the GH shift can be large inside the reflection (amplification) band and becomes extremely large as the PT symmetry-breaking threshold is approached.

  14. Wavelength-tunable laser based on nonlinear dispersive-wave generation in a tapered optical waveguide

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a method and a wavelength tunable laser comprising a first laser source configured to emit a first optical pulse having a pump wavelength, the first optical pulse being emitted in a first longitudinal direction. Furthermore, the wavelength tunable laser comprises...... a waveguide extending in the first longitudinal direction, the waveguide having longitudinally varying phase matching conditions, the waveguide being configured to generate a second optical pulse with a centre wavelength upon receiving the first optical pulse, wherein the wavelength tunable laser...... is configured to tune the centre wavelength of the second optical pulse by varying at least one pulse property of the first optical pulse....

  15. Wavelength dependence of the bidirectional reflectance distribution function (BRDF) of beach sands.

    Science.gov (United States)

    Doctor, Katarina Z; Bachmann, Charles M; Gray, Deric J; Montes, Marcos J; Fusina, Robert A

    2015-11-01

    The wavelength dependence of the dominant directional reflective properties of beach sands was demonstrated using principal component analysis and the related correlation matrix. In general, we found that the hyperspectral bidirectional reflectance distribution function (BRDF) of beach sands has weak wavelength dependence. Its BRDF varies slightly in three broad wavelength regions. The variations are more evident in surfaces of greater visual roughness than in smooth surfaces. The weak wavelength dependence of the BRDF of beach sand can be captured using three broad wavelength regions instead of hundreds of individual wavelengths.

  16. Reduced Tolerance to Night Shift in Chronic Shift Workers: Insight From Fractal Regulation.

    Science.gov (United States)

    Li, Peng; Morris, Christopher J; Patxot, Melissa; Yugay, Tatiana; Mistretta, Joseph; Purvis, Taylor E; Scheer, Frank A J L; Hu, Kun

    2017-07-01

    Healthy physiology is characterized by fractal regulation (FR) that generates similar structures in the fluctuations of physiological outputs at different time scales. Perturbed FR is associated with aging and age-related pathological conditions. Shift work, involving repeated and chronic exposure to misaligned environmental and behavioral cycles, disrupts circadian coordination. We tested whether night shifts perturb FR in motor activity and whether night shifts affect FR in chronic shift workers and non-shift workers differently. We studied 13 chronic shift workers and 14 non-shift workers as controls using both field and in-laboratory experiments. In the in-laboratory study, simulated night shifts were used to induce a misalignment between the endogenous circadian pacemaker and the sleep-wake cycles (ie, circadian misalignment) while environmental conditions and food intake were controlled. In the field study, we found that FR was robust in controls but broke down in shift workers during night shifts, leading to more random activity fluctuations as observed in patients with dementia. The night shift effect was present even 2 days after ending night shifts. The in-laboratory study confirmed that night shifts perturbed FR in chronic shift workers and showed that FR in controls was more resilience to the circadian misalignment. Moreover, FR during real and simulated night shifts was more perturbed in those who started shift work at older ages. Chronic shift work causes night shift intolerance, which is probably linked to the degraded plasticity of the circadian control system. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  17. Fiber Bragg grating interrogation using wavelength modulated tunable distributed feedback lasers and a fiber-optic Mach-Zehnder interferometer.

    Science.gov (United States)

    Roy, Anirban; Chakraborty, Arup Lal; Jha, Chandan Kumar

    2017-04-20

    This paper demonstrates a technique of high-resolution interrogation of two fiber Bragg gratings (FBGs) with flat-topped reflection spectra centered on 1649.55 nm and 1530.182 nm with narrow line width tunable semiconductor lasers emitting at 1651.93 nm and 1531.52 nm, respectively. The spectral shift of the reflection spectrum in response to temperature and strain is accurately measured with a fiber-optic Mach-Zehnder interferometer that has a free spectral range of 0.0523 GHz and a broadband photodetector. Laser wavelength modulation and harmonic detection techniques are used to transform the gentle edges of the flat-topped FBG into prominent leading and trailing peaks that are up to five times narrower than the FBG spectrum. Either of these peaks can be used to accurately measure spectral shifts of the FBG reflection spectrum with a resolution down to a value of 0.47 pm. A digital signal processing board is used to measure the temperature-induced spectral shifts over the range of 30°C-80°C and strain-induced spectral shifts from 0  μϵ to 12,000  μϵ. The shift is linear in both cases with a temperature sensitivity of 12.8 pm/°C and strain sensitivity of 0.12  pm/μϵ. The distinctive feature of this technique is that it does not use an optical spectrum analyzer at any stage of its design or operation. It can be readily extended to all types of tunable diode lasers and is ideally suited for compact field instruments and for biomedical applications in stroke rehabilitation monitoring.

  18. Enhancing the blue shift of SHG signal in GaSe:B/Ce crystal

    Science.gov (United States)

    Karatay, Ahmet; Yuksek, Mustafa; Ertap, Hüseyin; Elmali, Ayhan; Karabulut, Mevlut

    2018-02-01

    The influence of Ce3+ on the wavelength of second harmonic generation (SHG) signal in boron doped GaSe crystals have been investigated. We found that by substitution of Ce3+ with B3+, SHG signal shifted to lower wavelength. In addition, the nonlinear absorption (NA) properties and ultrafast dynamics of pure, 1 at.% B3+ and 0.5 at.% B3++ 0.5 at.% Ce3+ doped GaSe crystals have been studied by open aperture Z-scan and ultrafast pump probe spectroscopy techniques. From the open aperture Z-scan experiments we observed that all of the crystals showed nonlinear absorption (NA). However, pump-probe experiments revealed that when GaSe crystal is doped, the NA signal turns into a bleaching signal with different lifetimes depending on the type and concentration of the dopant atoms.

  19. Highly birefringent phase-shifted fiber Bragg gratings inscribed with femtosecond laser.

    Science.gov (United States)

    He, Jun; Wang, Yiping; Liao, Changrui; Wang, Qiaoni; Yang, Kaiming; Sun, Bing; Yin, Guolu; Liu, Shen; Zhou, Jiangtao; Zhao, Jing

    2015-05-01

    We demonstrate a highly birefringent phase-shifted fiber Bragg grating (PS-FBG) inscribed in H2-free fiber with a near-infrared femtosecond Gaussian laser beam and uniform phase mask. The PS-FBG was fabricated from an ordinary fiber Bragg grating (FBG) in a case in which overexposure was applied. The spectral evolution from FBG to FS-FBG was observed experimentally with a decrease in transmission loss at dip wavelength, blueshift of the dip wavelength, decrease in the cladding mode loss, and an increase in the insertion loss. A high birefringence was demonstrated experimentally with the existence of PS-FBG only in TM polarization. The formation of the PS-FBG may be due to a negative index change induced by the higher intensity in the center of the Gaussian laser beam.

  20. Objective identification of informative wavelength regions in galaxy spectra

    Energy Technology Data Exchange (ETDEWEB)

    Yip, Ching-Wa; Szalay, Alexander S.; Budavári, Tamás; Wyse, Rosemary F. G. [Department of Physics and Astronomy, The Johns Hopkins University, 3701 San Martin Drive, Baltimore, MD 21218 (United States); Mahoney, Michael W. [Department of Mathematics, Stanford University, Stanford, CA 94305 (United States); Csabai, István; Dobos, Laszlo, E-mail: cwyip@pha.jhu.edu, E-mail: szalay@jhu.edu, E-mail: mmahoney@cs.stanford.edu [Department of Physics of Complex Systems, Eötvös Loránd University, H-1117 Budapest (Hungary)

    2014-05-01

    Understanding the diversity in spectra is the key to determining the physical parameters of galaxies. The optical spectra of galaxies are highly convoluted with continuum and lines that are potentially sensitive to different physical parameters. Defining the wavelength regions of interest is therefore an important question. In this work, we identify informative wavelength regions in a single-burst stellar population model using the CUR Matrix Decomposition. Simulating the Lick/IDS spectrograph configuration, we recover the widely used D {sub n}(4000), Hβ, and Hδ {sub A} to be most informative. Simulating the Sloan Digital Sky Survey spectrograph configuration with a wavelength range 3450-8350 Å and a model-limited spectral resolution of 3 Å, the most informative regions are: first region—the 4000 Å break and the Hδ line; second region—the Fe-like indices; third region—the Hβ line; and fourth region—the G band and the Hγ line. A principal component analysis on the first region shows that the first eigenspectrum tells primarily the stellar age, the second eigenspectrum is related to the age-metallicity degeneracy, and the third eigenspectrum shows an anti-correlation between the strengths of the Balmer and the Ca K and H absorptions. The regions can be used to determine the stellar age and metallicity in early-type galaxies that have solar abundance ratios, no dust, and a single-burst star formation history. The region identification method can be applied to any set of spectra of the user's interest, so that we eliminate the need for a common, fixed-resolution index system. We discuss future directions in extending the current analysis to late-type galaxies. ASCII formatted tables of the regional eigenspectra are available.