WorldWideScience

Sample records for single mode emission

  1. Single-Mode VCSELs

    Science.gov (United States)

    Larsson, Anders; Gustavsson, Johan S.

    The only active transverse mode in a truly single-mode VCSEL is the fundamental mode with a near Gaussian field distribution. A single-mode VCSEL produces a light beam of higher spectral purity, higher degree of coherence and lower divergence than a multimode VCSEL and the beam can be more precisely shaped and focused to a smaller spot. Such beam properties are required in many applications. In this chapter, after discussing applications of single-mode VCSELs, we introduce the basics of fields and modes in VCSELs and review designs implemented for single-mode emission from VCSELs in different materials and at different wavelengths. This includes VCSELs that are inherently single-mode as well as inherently multimode VCSELs where higher-order modes are suppressed by mode selective gain or loss. In each case we present the current state-of-the-art and discuss pros and cons. At the end, a specific example with experimental results is provided and, as a summary, the most promising designs based on current technologies are identified.

  2. Design of Slow and Fast Light Photonic Crystal Waveguides for Single-photon Emission Using a Bloch Mode Expansion Technique

    DEFF Research Database (Denmark)

    de Lasson, Jakob Rosenkrantz; Rigal, B.; Kapon, E.

    We design slow and fast light photonic crystal waveguides for single-photon emission using a Bloch mode expansion and scattering matrix technique. We propose slow light designs that increase the group index-waveguide mode volume ratio for larger Purcell enhancement, and address efficient slow-to-...

  3. Watt-level widely tunable single-mode emission by injection-locking of a multimode Fabry-Perot quantum cascade laser

    Science.gov (United States)

    Chevalier, Paul; Piccardo, Marco; Anand, Sajant; Mejia, Enrique A.; Wang, Yongrui; Mansuripur, Tobias S.; Xie, Feng; Lascola, Kevin; Belyanin, Alexey; Capasso, Federico

    2018-02-01

    Free-running Fabry-Perot lasers normally operate in a single-mode regime until the pumping current is increased beyond the single-mode instability threshold, above which they evolve into a multimode state. As a result of this instability, the single-mode operation of these lasers is typically constrained to few percents of their output power range, this being an undesired limitation in spectroscopy applications. In order to expand the span of single-mode operation, we use an optical injection seed generated by an external-cavity single-mode laser source to force the Fabry-Perot quantum cascade laser into a single-mode state in the high current range, where it would otherwise operate in a multimode regime. Utilizing this approach, we achieve single-mode emission at room temperature with a tuning range of 36 cm-1 and stable continuous-wave output power exceeding 1 W at 4.5 μm. Far-field measurements show that a single transverse mode is emitted up to the highest optical power, indicating that the beam properties of the seeded Fabry-Perot laser remain unchanged as compared to free-running operation.

  4. Statistical properties of single-mode emission in free-electron lasers

    International Nuclear Information System (INIS)

    Bertolotti, M.; Luks, A.; Perina, J.; Perinova, V.; Sibilia, C.

    1984-01-01

    The authors of this paper discuss the statistical properties of radiation produced in the free electron laser, in the case of singlemode emission when the system is used as an amplifier, with very small gain. The coherent states technique and the q-c number correspondence is employed, starting from the master-equation and obtaining the generalized Fokker-Planck equation for the anti-normal quasidistribution function. Solutions of Fokker-Planck equation provide the photocounting distribution and its factorial moments. No losses are included. It is shown that, in the short-time approximation, the radiation field exhibits antibunching, and that the photocounting distributions, when some suitable conditions on the field intensities are fulfilled, in the stationary regime shows a two-peak behavior, evidencing the existence of bistable states

  5. Single photon emission tomography

    International Nuclear Information System (INIS)

    Buvat, Irene

    2011-09-01

    The objective of this lecture is to present the single photon emission computed tomography (SPECT) imaging technique. Content: 1 - Introduction: anatomic, functional and molecular imaging; Principle and role of functional or molecular imaging; 2 - Radiotracers: chemical and physical constraints, main emitters, radioisotopes production, emitters type and imaging techniques; 3 - Single photon emission computed tomography: gamma cameras and their components, gamma camera specifications, planar single photon imaging characteristics, gamma camera and tomography; 4 - Quantification in single photon emission tomography: attenuation, scattering, un-stationary spatial resolution, partial volume effect, movements, others; 5 - Synthesis and conclusion

  6. Single-mode biological distributed feedback laser

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Maier-Flaig, Florian; Lemmer, Uli

    2013-01-01

    Single-mode second order distributed feedback (DFB) lasers of riboflavin (vitamin B2) doped gelatine films on nanostructured low refractive index material are demonstrated. Manufacturing is based on a simple UV nanoimprint and spin-coating. Emission wavelengths of 543 nm and 562 nm for two...

  7. Single-mode optical fibres

    CERN Document Server

    Cancellieri, G

    1991-01-01

    This book describes signal propagation in single-mode optical fibres for telecommunication applications. Such description is based on the analysis of field propagation, considering waveguide properties and also some of the particular characteristics of the material fibre. The book covers such recent advances as, coherent transmissions; optical amplification; MIR fibres; polarization maintaining; polarization diversity and photon counting.

  8. Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Schlehahn, A.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T., E-mail: tobias.heindel@tu-berlin.de; Reitzenstein, S. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin 10623 (Germany); Gaafar, M.; Vaupel, M.; Stolz, W.; Rahimi-Iman, A.; Koch, M. [Department of Physics and Materials Science Center, Philipps-Universität Marburg, 35032 Marburg (Germany)

    2015-07-27

    We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g{sup (2)}(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

  9. Single-photon emission computed tomography

    International Nuclear Information System (INIS)

    Budinger, T.F.

    1986-01-01

    Single photon tomography dates from the early 1960's when the idea of emission transverse section tomography was presented by Kuhl and Edwards. They used a rectilinear scanner and analogue back-projection methods to detect emissions from a series of sequential positions transverse to the cephaldcaudad axis of the body. This chapter presents an explanation of emission tomography by describing longitudinal and transverse section tomography. In principle all modes of tomography can be considered under the general topic of coded apertures wherein the code ranges from translation of a pinhole collimator to rotation of a parallel hole or focused collimator array

  10. A novel high-efficiency single-mode quantum dot single photon source

    DEFF Research Database (Denmark)

    Gerard, J.M.; Gregersen, Niels; Nielsen, Torben Roland

    2008-01-01

    We present a novel single-mode single photon source exploiting the emission of a semiconductor quantum dot (QD) located inside a photonic wire. Besides an excellent coupling (>95%) of QD spontaneous emission to the fundamental guided mode [1], we show that a single photon collection efficiency...... above 80% within a 0.5 numerical aperture can be achieved using a bottom Bragg mirror and a tapering of the nanowire tip. Because this photon collection strategy does not exploit the Purcell effect, it could also be efficiently applied to broadband single photon emitters such as F-centers in diamond....

  11. Absorption and emission from mode conversion theory

    International Nuclear Information System (INIS)

    Swanson, D.G.

    1995-02-01

    The effects of mode conversion theory on emission have led to some surprising results. The classical expressions were originally derived from models which did not include mode conversion or its attendant reflection. When mode conversion was included, the first surprise was that the transmission coefficient is totally independent of absorption and due exclusively to tunneling. The other surprise is that the observed emission arises from two distinct sources, one direct, and one from an indirect Bernstein wave source which is partially converted in the cyclotron layer to outgoing electromagnetic waves, with the net result that mode conversion cancels out for the electron case. The only corrections to electron cyclotron emission are then due to reflection effects, and these have been shown to be small for laboratory plasmas, leading to the validation of the classical formula, but via an entirely new paradigm in its interpretation. This paper includes a summary of the absorption process for electron cyclotron harmonics, and reviews the emission physics, including both potential error estimates and a discussion of the spatial emission source distribution

  12. 1.9 W continuous-wave single transverse mode emission from 1060 nm edge-emitting lasers with vertically extended lasing area

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. J., E-mail: jarez.miah@tu-berlin.de; Posilovic, K.; Kalosha, V. P.; Rosales, R.; Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Kettler, T. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); PBC Lasers GmbH, Hardenbergstr. 36, 10623 Berlin (Germany); Skoczowsky, D. [PBC Lasers GmbH, Hardenbergstr. 36, 10623 Berlin (Germany); Pohl, J.; Weyers, M. [Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany)

    2014-10-13

    High-brightness edge-emitting semiconductor lasers having a vertically extended waveguide structure emitting in the 1060 nm range are investigated. Ridge waveguide (RW) lasers with 9 μm stripe width and 2.64 mm cavity length yield highest to date single transverse mode output power for RW lasers in the 1060 nm range. The lasers provide 1.9 W single transverse mode optical power under continuous-wave (cw) operation with narrow beam divergences of 9° in lateral and 14° (full width at half maximum) in vertical direction. The beam quality factor M{sup 2} is less than 1.9 up to 1.9 W optical power. A maximum brightness of 72 MWcm{sup −2}sr{sup −1} is obtained. 100 μm wide and 3 mm long unpassivated broad area lasers provide more than 9 W optical power in cw operation.

  13. Single mode dye-doped polymer photonic crystal lasers

    International Nuclear Information System (INIS)

    Christiansen, Mads B; Buß, Thomas; Smith, Cameron L C; Petersen, Sidsel R; Jørgensen, Mette M; Kristensen, Anders

    2010-01-01

    Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e.g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be −0.045 or −0.066 nm K -1 , depending on the material

  14. Single mode dye-doped polymer photonic crystal lasers

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron

    2010-01-01

    Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode...... emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e. g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be -0.045 or -0...

  15. Single-mode coherent synchrotron radiation instability

    Directory of Open Access Journals (Sweden)

    S. Heifets

    2003-06-01

    Full Text Available The microwave instability driven by the coherent synchrotron radiation (CSR has been previously studied [S. Heifets and G. V. Stupakov, Phys. Rev. ST Accel. Beams 5, 054402 (2002] neglecting effect of the shielding caused by the finite beam pipe aperture. In practice, the unstable mode can be close to the shielding threshold where the spectrum of the radiation in a toroidal beam pipe is discrete. In this paper, the CSR instability is studied in the case when it is driven by a single synchronous mode. A system of equations for the beam-wave interaction is derived and its similarity to the 1D free-electron laser theory is demonstrated. In the linear regime, the growth rate of the instability is obtained and a transition to the case of continuous spectrum is discussed. The nonlinear evolution of the single-mode instability, both with and without synchrotron damping and quantum diffusion, is also studied.

  16. Single-mode Laser by Parity-time Symmetry Breaking

    Science.gov (United States)

    2014-11-21

    solenoid -like Pds5B that reside in direct proximity to Wapl and the Smc3-Scc1 in- teraction interface (fig. S13), implying that Wapl and Pds5 control the...accepted 26 September 2014 10.1126/science.1256904 REPORTS ◥ OPTICS Single-mode laser by parity-time symmetry breaking Liang Feng,1* Zi Jing Wong,1...Ren-Min Ma,1* Yuan Wang,1,2 Xiang Zhang1,2† Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and

  17. Holograms for laser diode: Single mode optical fiber coupling

    Science.gov (United States)

    Fuhr, P. L.

    1982-01-01

    The low coupling efficiency of semiconductor laser emissions into a single mode optical fibers place a severe restriction on their use. Associated with these conventional optical coupling techniques are stringent alignment sensitivities. Using holographic elements, the coupling efficiency may be increased and the alignment sensitivity greatly reduced. Both conventional and computer methods used in the generation of the holographic couplers are described and diagrammed. The reconstruction geometries used are shown to be somewhat restrictive but substantially less rigid than their conventional optical counterparts. Single and double hologram techniques are examined concerning their respective ease of fabrication and relative merits.

  18. Single-mode surface plasmon distributed feedback lasers.

    Science.gov (United States)

    Karami Keshmarzi, Elham; Tait, R Niall; Berini, Pierre

    2018-03-29

    Single-mode surface plasmon distributed feedback (DFB) lasers are realized in the near infrared using a two-dimensional non-uniform long-range surface plasmon polariton structure. The surface plasmon mode is excited onto a 20 nm-thick, 1 μm-wide metal stripe (Ag or Au) on a silica substrate, where the stripe is stepped in width periodically, forming a 1st order Bragg grating. Optical gain is provided by optically pumping a 450 nm-thick IR-140 doped PMMA layer as the top cladding, which covers the entire length of the Bragg grating, thus creating a DFB laser. Single-mode lasing peaks of very narrow linewidth were observed for Ag and Au DFBs near 882 nm at room temperature. The narrow linewidths are explained by the low spontaneous emission rate into the surface plasmon lasing mode as well as the high quality factor of the DFB structure. The lasing emission is exclusively TM polarized. Kinks in light-light curves accompanied by spectrum narrowing were observed, from which threshold pump power densities can be clearly identified (0.78 MW cm-2 and 1.04 MW cm-2 for Ag and Au DFB lasers, respectively). The Schawlow-Townes linewidth for our Ag and Au DFB lasers is estimated and very narrow linewidths are predicted for the lasers. The lasers are suitable as inexpensive, recyclable and highly coherent sources of surface plasmons, or for integration with other surface plasmon elements of similar structure.

  19. Single photon emission computerized tomography

    International Nuclear Information System (INIS)

    Hooge, P. de.

    1983-01-01

    In this thesis two single-photon emission tomographic techniques are presented: (a) longitudinal tomography with a rotating slanting-hole collimator, and (b) transversal tomography with a rotating gamma camera. These methods overcome the disadvantages of conventional scintigraphy. Both detection systems and the image construction methods are explained and comparisons with conventional scintigraphy are drawn. One chapter is dedicated to the determination of system parameters like spatial resolution, contrast, detector uniformity, and size of the object, by phantom studies. In separate chapters the results are presented of detection of tumors and metastases in the liver and the liver hilus; skeletal diseases; various pathological aberrations of the brain; and myocardial perfusion. The possible use of these two ect's for other organs and body areas is discussed in the last chapter. (Auth.)

  20. Single-mode fiber laser based on core-cladding mode conversion.

    Science.gov (United States)

    Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

    2008-02-15

    A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

  1. Single photon detection in the SQS mode

    International Nuclear Information System (INIS)

    Alves, M.A.; Fraga, M.M.; Lima, E.P. de; Marques, R.F.; Neves, F.; Policarpo, A.

    1997-01-01

    Results are presented concerning the detection of single UV photons in self quenching streamer detectors by photoionization of one of the gas mixture components, in this case TEA (tri ethyl-amine), whose molecules have low photoionization potential and large absorption cross section. As a UV light source, a gas scintillation counter filled with krypton was used, whose emission light spectrum, centered at approximately 150 nm, overlaps well the photoionization spectrum of TEA. The mixtures studied were argon/ethane/TEA, argon/isobutane/TEA, argon/ethane/methylal/TEA and argon/isobutane/methylal/ TEA. (author). 4 refs., 4 figs

  2. Alcohol sensor based on single-mode-multimode-single-mode fiber structure

    Science.gov (United States)

    Mefina Yulias, R.; Hatta, A. M.; Sekartedjo, Sekartedjo

    2016-11-01

    Alcohol sensor based on Single-mode -Multimode-Single-mode (SMS) fiber structure is being proposed to sense alcohol concentration in alcohol-water mixtures. This proposed sensor uses refractive index sensing as its sensing principle. Fabricated SMS fiber structure had 40 m of multimode length. With power input -6 dBm and wavelength 1550 nm, the proposed sensor showed good response with sensitivity 1,983 dB per % v/v with measurement range 05 % v/v and measurement span 0,5% v/v.

  3. Single-mode operation of a coiled multimode fiber amplifier

    International Nuclear Information System (INIS)

    Koplow, Jeffrey P.; Kliner, Dahv A. V.; Goldberg, Lew

    2000-01-01

    We report a new approach to obtaining single-transverse-mode operation of a multimode fiber amplifier in which the gain fiber is coiled to induce significant bend loss for all but the lowest-order mode. We demonstrated this method by constructing a coiled amplifier using Yb-doped, double-clad fiber with a core diameter of 25 μm and a numerical aperture of ∼0.1 (V≅7.4) . When the amplifier was operated as an amplified-spontaneous-emission source, the output beam had an M 2 value of 1.09±0.09 ; when seeded at 1064 nm, the slope efficiency was similar to that of an uncoiled amplifier. This technique will permit scaling of pulsed fiber lasers and amplifiers to significantly higher pulse energies and peak powers and cw fiber sources to higher average powers while maintaining excellent beam quality. (c) 2000 Optical Society of America

  4. Inhibited emission of electromagnetic modes confined in subwavelength cavities

    International Nuclear Information System (INIS)

    Le Thomas, N.; Houdre, R.

    2011-01-01

    We experimentally demonstrate the active inhibition of subwavelength confined cavity modes emission and quality factor enhancement by controlling the cavity optical surrounding. The intrinsic radiation angular spectrum of modes confined in planar photonics crystal cavities as well as its modifications depending on the environment are inferred via a transfer matrix modeling and k-space imaging.

  5. Optimize Etching Based Single Mode Fiber Optic Temperature Sensor

    OpenAIRE

    Ajay Kumar; Dr. Pramod Kumar

    2014-01-01

    This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF) optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that th...

  6. Mode coupling in hybrid square-rectangular lasers for single mode operation

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xiu-Wen; Huang, Yong-Zhen, E-mail: yzhuang@semi.ac.cn; Yang, Yue-De; Xiao, Jin-Long; Weng, Hai-Zhong; Xiao, Zhi-Xiong [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100083 (China)

    2016-08-15

    Mode coupling between a square microcavity and a Fabry-Pérot (FP) cavity is proposed and demonstrated for realizing single mode lasers. The modulations of the mode Q factor as simulation results are observed and single mode operation is obtained with a side mode suppression ratio of 46 dB and a single mode fiber coupling loss of 3.2 dB for an AlGaInAs/InP hybrid laser as a 300-μm-length and 1.5-μm-wide FP cavity connected to a vertex of a 10-μm-side square microcavity. Furthermore, tunable single mode operation is demonstrated with a continuous wavelength tuning range over 10 nm. The simple hybrid structure may shed light on practical applications of whispering-gallery mode microcavities in large-scale photonic integrated circuits and optical communication and interconnection.

  7. Crosstalk-Managed Heterogeneous Single-Mode 32-Core Fibre

    DEFF Research Database (Denmark)

    Sasaki, Y.; Fukumoto, Ryohei; Takenaga, Katsuhiro

    2016-01-01

    A heterogeneous single-mode 32-core fibre with a cladding diameter of 243 micrometer is designed and fabricated. The highest core count in single-mode multi-core fibres and low worst-case crosstalk of less than -24 dB/1000 km in C-band are achieved simultaneously....

  8. Physics and technology of tunable pulsed single longitudinal mode ...

    Indian Academy of Sciences (India)

    Design and technology demonstration of compact, narrow bandwidth, high repetition rate, tunable SLM dye lasers in two different configurations, namely Littrow and grazing incidence grating (GIG), were carried out in our lab at BARC, India. The single longitudinal mode (SLM) dye laser generates single-mode laser beams ...

  9. The magnetoionic modes and propagation properties of auroral radio emissions

    International Nuclear Information System (INIS)

    Calvert, W.; Hashimoto, Kozo

    1990-01-01

    The different magnetoionic wave modes which accompany the aurora are identified using DE 1 not only by their appearance on satellite radio spectrograms, but also by concurrent measurements of their wave polarization and arrival directions, and by ray-tracing models of their expected propagation behavior. Of the four possible propagation modes, designated O, X, W, and Z for the ordinary, extraordinary, whistler, and Z modes, respectively, all four are found to occur in the auroral zone, as follows: The most intense, of course, is the well-known auroral kilometric radiation (AKR), which originates primarily in the X mode near the electron cyclotron frequency, but which is frequently also accompanied by a weaker O-mode component from the same location. The next most prominent auroral emission is the W-mode auroral hiss originating from altitudes always well below the DE 1 satellite at frequencies below the local cyclotron frequency. The previously reported Z-mode auroral radiation was also detected, but from sources also below the satellite and at the poleward edge of the cavity, and not from the expected AKR source at the cyclotron frequency. A weaker O-mode component seems to accompany these emissions also, both within the polar cap poleward of the source and inside the cavity, the latter seemingly being guided upward by the cavity's lower plasma densities. Finally, exactly on the source field lines at the poleward edge of the cavity, there also occasionally seems to be localized Z-mode emissions extending from the Z-mode cutoff at quite low frequencies up to and above the plasma frequency

  10. Cross-correlated imaging of single-mode photonic crystal rod fiber with distributed mode filtering

    DEFF Research Database (Denmark)

    Laurila, Marko; Barankov, Roman; Jørgensen, Mette Marie

    2013-01-01

    Photonic crystal bandgap fibers employing distributed mode filtering design provide near diffraction-limited light outputs, a critical property of fiber-based high-power lasers. Microstructure of the fibers is tailored to achieve single-mode operation at specific wavelength by resonant mode...... identify regimes of resonant coupling between higher-order core modes and cladding band. We demonstrate a passive fiber design in which the higher-order modal content inside the single-mode guiding regime is suppressed by at least 20 dB even for significantly misaligned input-coupling configurations....

  11. Single ion implantation for single donor devices using Geiger mode detectors

    International Nuclear Information System (INIS)

    Bielejec, E; Seamons, J A; Carroll, M S

    2010-01-01

    Electronic devices that are designed to use the properties of single atoms such as donors or defects have become a reality with recent demonstrations of donor spectroscopy, single photon emission sources, and magnetic imaging using defect centers in diamond. Ion implantation, an industry standard for atom placement in materials, requires augmentation for single ion capability including a method for detecting a single ion arrival. Integrating single ion detection techniques with the single donor device construction region allows single ion arrival to be assured. Improving detector sensitivity is linked to improving control over the straggle of the ion as well as providing more flexibility in lay-out integration with the active region of the single donor device construction zone by allowing ion sensing at potentially greater distances. Using a remotely located passively gated single ion Geiger mode avalanche diode (SIGMA) detector we have demonstrated 100% detection efficiency at a distance of >75 μm from the center of the collecting junction. This detection efficiency is achieved with sensitivity to ∼600 or fewer electron-hole pairs produced by the implanted ion. Ion detectors with this sensitivity and integrated with a thin dielectric, for example a 5 nm gate oxide, using low energy Sb implantation would have an end of range straggle of -1 and 10 -4 for operation temperatures of ∼300 K and ∼77 K, respectively. Low temperature operation and reduced false, 'dark', counts are critical to achieving high confidence in single ion arrival. For the device performance in this work, the confidence is calculated as a probability of >98% for counting one and only one ion for a false count probability of 10 -4 at an average ion number per gated window of 0.015.

  12. Development of IR single mode optical fibers for DARWIN-nulling interferometry

    NARCIS (Netherlands)

    Chakkalakkal Abdulla, S.M.; Cheng, L.K.; Bosch, B. van den; Dijkhuizen, N.; Nieuwland, R.A.; Gielesen, W.L.M.; Lucas, J.; Boussard-Plédel, C.; Conseil, C.; Bureau, B.; Carmo, J.P. do

    2014-01-01

    The DARWIN mission aims to detect weak infra-red emission lines from distant orbiting earth-like planets using nulling interferometry. This requires filtering of wavefront errors using single mode waveguides operating at a wavelength range of 6.5-20 μm. This article describes the optical design of

  13. Physics and technology of tunable pulsed single longitudinal mode ...

    Indian Academy of Sciences (India)

    precious materials. In particular, single-longitudinal mode dye lasers are useful ... to the longitudinal mode spacing of 10 GHz. Grating of 3300 .... the band of wavelength covering 3 pm and SLM operation was shown in the band of 0.5 pm.

  14. LOPUT Laser: A novel concept to realize single longitudinal mode ...

    Indian Academy of Sciences (India)

    2014-02-05

    Feb 5, 2014 ... Abstract. We propose a novel type of cavity design to generate single longitudinal mode laser known as LOPUT cavity. LOPUT cavity stands for linear orthogonally polarized modes resulting in unidirectional travelling wave cavity. The technique can be applied to both isotropic as well as anisotropic gain ...

  15. Quasi-single-mode homogeneous 31-core fibre

    DEFF Research Database (Denmark)

    Sasaki, Y.; Saitoh, S.; Amma, Y.

    2015-01-01

    A homogeneous 31-core fibre with a cladding diameter of 230 μm for quasi-single-mode transmission is designed and fabricated. LP01-crosstalk of -38.4 dB/11 km at 1550 nm is achieved by using few-mode trench-assisted cores....

  16. Radiation-induced transient absorption in single mode optical fibers

    International Nuclear Information System (INIS)

    Looney, L.D.; Lyons, P.B.

    1988-01-01

    This paper reviews the measurements conducted by the Los Alamos National Laboratory in support of these NATO efforts wherein radiation-induced transient absorption was measured over time ranges from a few ns to several μs for two single mode fibers. Experimental conditions were varied to provide data for future development of standarized test conditions for single mode fibers. 8 refs., 11 figs

  17. Damping of unbound single-particle modes

    International Nuclear Information System (INIS)

    Fortier, S.; Beaumel, D.; Gales, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J.M.

    1995-07-01

    The (α, 3 He-n) reaction has been investigated at 120 MeV incident energy on 64 Ni, 90 Zr and 120 Sn target nuclei. Neutrons in coincidence with 3 He particles emitted at 0 deg were detected, in order to get information about the decay of single-particle states embedded in the (α, 3 He) continuum. Neutron angular correlations, multiplicity values and branching ratios to low-lying states of the final nuclei have been compared with the predictions of the statistical decay model. Direct branching ratios in 91 Zr deduced from this analysis are compared with the predictions of two nuclear structure models. (author)

  18. Damping of unbound single-particle modes

    International Nuclear Information System (INIS)

    Fortier, S.; Beaumel, D.; Gales, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J.M.; Bordewijk, J.; Brandenburg, S.; Krasznahorkay, A.; Crawley, G.M.; Massolo, C.P.; Renteria, M.; Khendriche, A.

    1995-01-01

    The (α, 3 He-n) reaction has been investigated at 120 MeV incident energy on 64 Ni, 90 Zr, and 120 Sn target nuclei. Neutrons in coincidence with 3 He particles emitted at 0 degree were detected using the multidetector array EDEN, in order to get information about the decay of single-particle states embedded in the (α, 3 He) continuum. Neutron angular correlations, multiplicity values, and branching ratios to low-lying states of the final nuclei have been compared with the predictions of the statistical decay model. Evidence for a significant nonstatistical decay branch has been observed in the three nuclei below about 15 MeV excitation energy. Direct branching ratios in 91 Zr deduced from this analysis are compared with the predictions of two nuclear structure models. At higher excitation energy, the decay characteristics of the (α, 3 He) continuum are shown to be mainly statistical

  19. Linear optical quantum computing in a single spatial mode.

    Science.gov (United States)

    Humphreys, Peter C; Metcalf, Benjamin J; Spring, Justin B; Moore, Merritt; Jin, Xian-Min; Barbieri, Marco; Kolthammer, W Steven; Walmsley, Ian A

    2013-10-11

    We present a scheme for linear optical quantum computing using time-bin-encoded qubits in a single spatial mode. We show methods for single-qubit operations and heralded controlled-phase (cphase) gates, providing a sufficient set of operations for universal quantum computing with the Knill-Laflamme-Milburn [Nature (London) 409, 46 (2001)] scheme. Our protocol is suited to currently available photonic devices and ideally allows arbitrary numbers of qubits to be encoded in the same spatial mode, demonstrating the potential for time-frequency modes to dramatically increase the quantum information capacity of fixed spatial resources. As a test of our scheme, we demonstrate the first entirely single spatial mode implementation of a two-qubit quantum gate and show its operation with an average fidelity of 0.84±0.07.

  20. Damping of unbound single-particle modes

    Energy Technology Data Exchange (ETDEWEB)

    Fortier, S.; Beaumel, D.; Gales, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J.M.; Bordewijk, J.; Brandenburg, S.; Krasznahorkay, A.; Crawley, G.M.; Massolo, C.P.; Renteria, M.; Khendriche, A. [Institut de Physique Nucleaire, IN2P3-CNRS, 91406 Orsay Cedex (France)]|[Kernfysisch Versneller Instituut, 9747 AA Groningen (Netherlands)]|[Nuclear Research Institute, Debrecen P.O. Box 51, H-4001 (Hungary)]|[NSCL, Michigan State University, East Lansing, Michigan 48824 (United States)]|[Dep. Fisica, Fac. Cs. Exactas, UNLP, CC Nio 67, 1900 La Plata (Argentina)]|[Institut de Sciences Exactes,Universite de Tizi-Ouzou, 15000 Tizi-Ouzou (Algeria)

    1995-11-01

    The ({alpha},{sup 3}He-{ital n}) reaction has been investigated at 120 MeV incident energy on {sup 64}Ni, {sup 90}Zr, and {sup 120}Sn target nuclei. Neutrons in coincidence with {sup 3}He particles emitted at 0{degree} were detected using the multidetector array EDEN, in order to get information about the decay of single-particle states embedded in the ({alpha},{sup 3}He) continuum. Neutron angular correlations, multiplicity values, and branching ratios to low-lying states of the final nuclei have been compared with the predictions of the statistical decay model. Evidence for a significant nonstatistical decay branch has been observed in the three nuclei below about 15 MeV excitation energy. Direct branching ratios in {sup 91}Zr deduced from this analysis are compared with the predictions of two nuclear structure models. At higher excitation energy, the decay characteristics of the ({alpha},{sup 3}He) continuum are shown to be mainly statistical.

  1. Direct detection of the optical field beyond single polarization mode.

    Science.gov (United States)

    Che, Di; Sun, Chuanbowen; Shieh, William

    2018-02-05

    Direct detection is traditionally regarded as a detection method that recovers only the optical intensity. Compared with coherent detection, it owns a natural advantage-the simplicity-but lacks a crucial capability of field recovery that enables not only the multi-dimensional modulation, but also the digital compensation of the fiber impairments linear with the optical field. Full-field detection is crucial to increase the capacity-distance product of optical transmission systems. A variety of methods have been investigated to directly detect the optical field of the single polarization mode, which normally sends a carrier traveling with the signal for self-coherent detection. The crux, however, is that any optical transmission medium supports at least two propagating modes (e.g. single mode fiber supports two polarization modes), and until now there is no direct detection that can recover the complete set of optical fields beyond one polarization, due to the well-known carrier fading issue after mode demultiplexing induced by the random mode coupling. To avoid the fading, direct detection receivers should recover the signal in an intensity space isomorphic to the optical field without loss of any degrees of freedom, and a bridge should be built between the field and its isomorphic space for the multi-mode field recovery. Based on this thinking, we propose, for the first time, the direct detection of dual polarization modes by a novel receiver concept, the Stokes-space field receiver (SSFR) and its extension, the generalized SSFR for multiple spatial modes. The idea is verified by a dual-polarization field recovery of a polarization-multiplexed complex signal over an 80-km single mode fiber transmission. SSFR can be applied to a much wider range of fields beyond optical communications such as coherent sensing and imaging, where simple field recovery without an extra local laser is desired for enhanced system performance.

  2. New results of investigations of whistler-mode chorus emissions

    Czech Academy of Sciences Publication Activity Database

    Santolík, Ondřej

    2008-01-01

    Roč. 15, č. 4 (2008), s. 621-630 ISSN 1023-5809 R&D Projects: GA AV ČR IAA301120601 Grant - others: NASA (US) NNX07AI24G; ESA PECS(XE) 98025 Institutional research plan: CEZ:AV0Z30420517 Keywords : chorus emissions * whistler-mode * Earth's magnetosphere Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.022, year: 2008 http://www.nonlin-processes-geophys.net/15/621/2008/

  3. A Calculation Method of PKA, KERMA and DPA from Evaluated Nuclear Data with an Effective Single-particle Emission Approximation (ESPEA) and Introduction of Event Generator Mode in PHITS Code

    International Nuclear Information System (INIS)

    Fukahori, Tokio; Iwamoto, Yosuke

    2012-01-01

    The displacement calculation method from evaluated nuclear data file has been developed by using effective single-particle emission approximation (ESPEA). The ESPEA can be used effectively below about 50 MeV, because of since multiplicity of emitted particles. These are also reported in the Ref. 24. The displacement calculation method in PHITS has been developed. In the high energy region (≥ 20 MeV) for proton and neutron beams, DPA created by secondary particles increase due to nuclear reactions. For heavy-ion beams, DPA created by the primaries are dominant to total DPA due to the large Coulomb scattering cross sections. PHITS results agree with FLUKA ones within a factor of 1.7. In the high-energy region above 10 MeV/nucleon, comparisons among codes and measurements of displacement damage cross section are necessary. (author)

  4. Terahertz light-emitting graphene-channel transistor toward single-mode lasing

    Science.gov (United States)

    Yadav, Deepika; Tamamushi, Gen; Watanabe, Takayuki; Mitsushio, Junki; Tobah, Youssef; Sugawara, Kenta; Dubinov, Alexander A.; Satou, Akira; Ryzhii, Maxim; Ryzhii, Victor; Otsuji, Taiichi

    2018-03-01

    A distributed feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) was fabricated as a current-injection terahertz (THz) light-emitting laser transistor. We observed a broadband emission in a 1-7.6-THz range with a maximum radiation power of 10 μW as well as a single-mode emission at 5.2 THz with a radiation power of 0.1 μW both at 100 K when the carrier injection stays between the lower cutoff and upper cutoff threshold levels. The device also exhibited peculiar nonlinear threshold-like behavior with respect to the current-injection level. The LED-like broadband emission is interpreted as an amplified spontaneous THz emission being transcended to a single-mode lasing. Design constraints on waveguide structures for better THz photon field confinement with higher gain overlapping as well as DFB cavity structures with higher Q factors are also addressed towards intense, single-mode continuous wave THz lasing at room temperature.

  5. High-power single-mode cw dye ring laser

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, H W; Stein, L; Froelich, D; Fugger, B; Welling, H [Technische Univ. Hannover (Germany, F.R.). Inst. fuer Angewandte Physik

    1977-12-01

    Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.

  6. Investigation of EBW Thermal Emission and Mode Conversion Physics in H-Mode Plasmas on NSTX

    International Nuclear Information System (INIS)

    Diem, S.J.; Taylor, G.; Efthimion, P.C.; Kugel, H.W.; LeBlanc, B.P.; Phillips, C.K.; Caughman, J.B.; Wilgen, J.B.; Harvey, R.W.; Preinhaelter, J.; Urban, J.; Sabbagh, S.A.

    2008-01-01

    High β plasmas in the National Spherical Torus Experiment (NSTX) operate in the overdense regime, allowing the electron Bernstein wave (EBW) to propagate and be strongly absorbed/emitted at the electron cyclotron resonances. As such, EBWs may provide local electron heating and current drive. For these applications, efficient coupling between the EBWs and electromagnetic waves outside the plasma is needed. Thermal EBW emission (EBE) measurements, via oblique B-X-O double mode conversion, have been used to determine the EBW transmission efficiency for a wide range of plasma conditions on NSTX. Initial EBE measurements in H-mode plasmas exhibited strong emission before the L-H transition, but the emission rapidly decayed after the transition. EBE simulations show that collisional damping of the EBW prior to the mode conversion (MC) layer can significantly reduce the measured EBE for T e < 20 eV, explaining the observations. Lithium evaporation was used to reduce EBE collisional damping near the MC layer. As a result, the measured B-X-O transmission efficiency increased from < 10% (no Li) to 60% (with Li), consistent with EBE simulations.

  7. Fibre Optic Sensors Using Adiabatically Tapered Single Mode Fibres

    Science.gov (United States)

    1994-02-01

    molecules were then coupled hack into the fundamental guided mode of the taper. The level of these emissions was characterised by using a monochromati’r...y y y Pae Ps4 Pase4 Pasc4_ Pase4jPase4 _Pasc4 I pase Plate 3: Can be the bof~tom of Plate 1 after it has been read. P7 28 29 3 31 1 32 PB I PG PG G2 P

  8. Single-particle states vs. collective modes: friends or enemies ?

    Science.gov (United States)

    Otsuka, T.; Tsunoda, Y.; Togashi, T.; Shimizu, N.; Abe, T.

    2018-05-01

    The quantum self-organization is introduced as one of the major underlying mechanisms of the quantum many-body systems. In the case of atomic nuclei as an example, two types of the motion of nucleons, single-particle states and collective modes, dominate the structure of the nucleus. The collective mode arises as the balance between the effect of the mode-driving force (e.g., quadrupole force for the ellipsoidal deformation) and the resistance power against it. The single-particle energies are one of the sources to produce such resistance power: a coherent collective motion is more hindered by larger spacings between relevant single particle states. Thus, the single-particle state and the collective mode are "enemies" against each other. However, the nuclear forces are rich enough so as to enhance relevant collective mode by reducing the resistance power by changing single-particle energies for each eigenstate through monopole interactions. This will be verified with the concrete example taken from Zr isotopes. Thus, the quantum self-organization occurs: single-particle energies can be self-organized by (i) two quantum liquids, e.g., protons and neutrons, (ii) monopole interaction (to control resistance). In other words, atomic nuclei are not necessarily like simple rigid vases containing almost free nucleons, in contrast to the naïve Fermi liquid picture. Type II shell evolution is considered to be a simple visible case involving excitations across a (sub)magic gap. The quantum self-organization becomes more important in heavier nuclei where the number of active orbits and the number of active nucleons are larger.

  9. An optical channel modeling of a single mode fiber

    Science.gov (United States)

    Nabavi, Neda; Liu, Peng; Hall, Trevor James

    2018-05-01

    The evaluation of the optical channel model that accurately describes the single mode fibre as a coherent transmission medium is reviewed through analytical, numerical and experimental analysis. We used the numerical modelling of the optical transmission medium and experimental measurements to determine the polarization drift as a function of time for a fixed length of fibre. The probability distribution of the birefringence vector was derived, which is associated to the 'Poole' equation. The theory and experimental evidence that has been disclosed in the literature in the context of polarization mode dispersion - Stokes & Jones formulations and solutions for key statistics by integration of stochastic differential equations has been investigated. Besides in-depth definition of the single-mode fibre-optic channel, the modelling which concerns an ensemble of fibres each with a different instance of environmental perturbation has been analysed.

  10. Semiconductor and ceramic microstructure made by single mode fiber laser

    International Nuclear Information System (INIS)

    Pawlak, R; Tomczyk, M; Walczak, M; Domagalski, P

    2014-01-01

    In the paper the results of micromachining of 3D microstructures of microsystems made from silicon and alumina ceramic using a single mode fiber laser (1064 nm) are presented. The quality of obtained structures and its smallest dimensions with acceptable maintained quality were examined. The influence of variable parameters of laser processing with changing of mapping scale on geometrical features of structures was identified.

  11. Spatially single-mode source of bright squeezed vacuum

    OpenAIRE

    Pérez, A. M.; Iskhakov, T. Sh.; Sharapova, P.; Lemieux, S.; Tikhonova, O. V.; Chekhova, M. V.; Leuchs, G.

    2014-01-01

    Bright squeezed vacuum, a macroscopic nonclassical state of light, can be obtained at the output of a strongly pumped non-seeded traveling-wave optical parametric amplifier (OPA). By constructing the OPA of two consecutive crystals separated by a large distance we make the squeezed vacuum spatially single-mode without a significant decrease in the brightness or squeezing.

  12. Measurement of flow fluctuations in single longitudinal mode pulsed ...

    Indian Academy of Sciences (India)

    2014-02-12

    Feb 12, 2014 ... Page 1 ... Keywords. Dye lasers; single longitudinal mode; flow fluctuations. PACS Nos 42.55.Mv; 42.60.Mi; 42.60.By. 1. Introduction. Narrow-band dye lasers offer ... stabilized tunable laser source plays an important role for many applications as mentioned above [1]. For tight wavelength control, the ...

  13. Single-mode multicore fiber for dense space division multiplexing

    DEFF Research Database (Denmark)

    Sasaki, Yusuke; Amma, Yoshimichi; Takenaga, Katsuhiro

    2016-01-01

    Single-mode multicore fiber (SM-MCF) is attractive for high-capacity transmission. Our fabricated SM-MCFs achieve high core count and low crosstalk with a cladding diameter of 230 µm. Characteristics of fan-in/fan-out for the SM-MCFs are also investigated....

  14. Saturation of single toroidal number Alfvén modes

    International Nuclear Information System (INIS)

    Wang, X; Briguglio, S

    2016-01-01

    The results of numerical simulations are presented to illustrate the saturation mechanism of a single toroidal number Alfvén mode, driven unstable, in a tokamak plasma, by the resonant interaction with energetic ions. The effects of equilibrium geometry non-uniformities and finite mode radial width on the wave-particle nonlinear dynamics are discussed. Saturation occurs as the fast-ion density flattening produced by the radial flux associated to the resonant particles captured in the potential well of the Alfvén wave extends over the whole region where mode-particle power exchange can take place. The occurrence of two different saturation regimes is shown. In the first regime, dubbed resonance detuning, that region is limited by the resonance radial width (that is, the width of the region where the fast-ion resonance frequency matches the mode frequency). In the second regime, called radial decoupling, the power exchange region is limited by the mode radial width. In the former regime, the mode saturation amplitude scales quadratically with the growth rate; in the latter, it scales linearly. The occurrence of one or the other regime can be predicted on the basis of linear dynamics: in particular, the radial profile of the fast-ion resonance frequency and the mode structure. Here, we discuss how such properties can depend on the considered toroidal number and compare simulation results with the predictions obtained from a simplified nonlinear pendulum model. (paper)

  15. Feedback stabilization system for pulsed single longitudinal mode tunable lasers

    Science.gov (United States)

    Esherick, Peter; Raymond, Thomas D.

    1991-10-01

    A feedback stabilization system for pulse single longitudinal mode tunable lasers having an excited laser medium contained within an adjustable length cavity and producing a laser beam through the use of an internal dispersive element, including detection of angular deviation in the output laser beam resulting from detuning between the cavity mode frequency and the passband of the internal dispersive element, and generating an error signal based thereon. The error signal can be integrated and amplified and then applied as a correcting signal to a piezoelectric transducer mounted on a mirror of the laser cavity for controlling the cavity length.

  16. Adapting the mode profile of planar waveguides to single-mode fibers : a novel method

    NARCIS (Netherlands)

    Smit, M.K.; Vreede, De A.H.

    1991-01-01

    A novel method for coupling single-mode fibers to planar optical circuits with small waveguide dimensions is proposed. The method eliminates the need to apply microoptics or to adapt the waveguide dimensions within the planar circuit to the fiber dimensions. Alignment tolerances are comparable to

  17. Research status of large mode area single polarization active fiber

    Science.gov (United States)

    Xiao, Chun; Zhang, Ge; Yang, Bin-hua; Cheng, Wei-feng; Gu, Shao-yi

    2018-03-01

    As high power fiber laser used more and more widely, to increase the output power of fiber laser and beam quality improvement have become an important goal for the development of high power fiber lasers. The use of large mode fiber is the most direct and effective way to solve the nonlinear effect and fiber damage in the fiber laser power lifting process. In order to reduce the effect of polarization of the fiber laser system, the study found that when introduces a birefringence in the single-mode fiber, the polarization state changes caused by the birefringence is far greater than the random polarization state changes, then the external disturbance is completely submerged, finally the polarization can be controlled and stabilized. Through the fine design of the fiber structure, if the birefringence is high enough to achieve the separation of the two polarization states, the fiber will have a different cut-off mechanism to eliminate polarization which is not need, which will realize single mode single polarization transmission in a band. In this paper, different types of single polarization fiber design are presented and the application of these fibers are also discussed.

  18. Vibration modes of a single plate with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Phamová L.

    2016-06-01

    Full Text Available This paper deals with free flexural vibration modes and natural frequencies of a thin plate with general boundary conditions — a simply supported plate connected to its surroundings with torsional springs. Vibration modes were derived on the basis of the Rajalingham, Bhat and Xistris approach. This approach was originally used for a clamped thin plate, so its adaptation was needed. The plate vibration function was usually expressed as a single partial differential equation. This partial differential equation was transformed into two ordinary differential equations that can be solved in the simpler way. Theoretical background of the computations is briefly described. Vibration modes of the supported plate with torsional springs are presented graphically and numerically for three different values of stiffness of torsional springs.

  19. Low-order longitudinal modes of single-component plasmas

    International Nuclear Information System (INIS)

    Tinkle, M.D.; Greaves, R.G.; Surko, C.M.

    1995-01-01

    The low-order modes of spheroidal, pure electron plasmas have been studied experimentally, both in a cylindrical electrode structure and in a quadrupole trap. Comparison is made between measurements of mode frequencies, recent analytical theories, and numerical simulations. Effects considered include trap anharmonicity, image charges, and temperature. Quantitative agreement is obtained between the predictions and these measurements for spheroidal plasmas in the quadrupole trap. In many experiments on single-component plasmas, including antimatter plasmas, the standard diagnostic techniques used to measure the density and temperature are not appropriate. A new method is presented for determining the size, shape, average density, and temperature of a plasma confined in a Penning trap from measurements of the mode frequencies. copyright 1995 American Institute of Physics

  20. Exact decoherence dynamics of a single-mode optical field

    International Nuclear Information System (INIS)

    An, J.-H.; Yeo Ye; Oh, C.H.

    2009-01-01

    We apply the influence-functional method of Feynman and Vernon to the study of a single-mode optical field that interacts with an environment at zero temperature. Using the coherent-state formalism of the path integral, we derive a generalized master equation for the single-mode optical field. Our analysis explicitly shows how non-Markovian effects manifest in the exact decoherence dynamics for different environmental correlation time scales. Remarkably, when these are equal to or greater than the time scale for significant change in the system, the interplay between the backaction-induced coherent oscillation and the dissipative effect of the environment causes the non-Markovian effect to have a significant impact not only on the short-time behavior but also on the long-time steady-state behavior of the system.

  1. Single mode operation of a TEA CO2 laser

    International Nuclear Information System (INIS)

    Wada, Kazuhiro; Tunawaki, Yoshiaki; Yamanaka, Masanobu.

    1993-01-01

    Single mode operation of a TEA CO 2 laser was performed by using an optical system of Fox-Smith type. Laser beam was taken out from the cavity by using a beam splitter, and was reflected by a mirror back to the cavity. By inserting a Fabry-Perot etalon between the splitter and the mirror, beat of laser pulses can be removed completly. (author)

  2. Positron emission tomography with gamma camera in coincidence mode

    International Nuclear Information System (INIS)

    Hertel, A.; Hoer, G.

    1999-01-01

    Positron emission tomography using F-18 FDG has been estbalished in clinical diagnostics with first indications especially in oncology. To install a conventional PET tomography (dedicated PET) is financially costly and restricted to PET examinations only. Increasing demand for PET diagnostics on one hand and restricted financial resources in the health system on the other hand led industry to develop SPECT cameras to be operated in coincidence mode (camera PET) in order to offer nuclear medicine physicians cost-effective devices for PET diagnostic. At the same time camera PET is inferior to conventional PET regarding sensitivity and detection-efficiency for 511 keV photons. Does camera-PET offer a reliable alternative to conventional PET? The first larger comparative studies are now available, so a first apraisal about the technical clinical performance of camera-PET can be done. (orig.) [de

  3. Low-loss single mode light waveguides in polymer

    Science.gov (United States)

    Sieber, Heinrich; Boehm, Hans-Jürgen; Hollenbach, Uwe; Mohr, Jürgen; Ostrzinski, Ute; Pfeiffer, Karl; Szczurowski, Marcin; Urbanczyk, Waclaw

    2012-06-01

    We report on the development of a UV-lithography manufacturing process for low loss single mode light waveguides in a novel polymer and the characterization of the fabricated components in a broad wavelength range from 808 nm to 1550 nm. The main focus of this work lies in providing a quick and cost efficient production technique for single mode waveguides and low loss integrated optical circuits. To achieve this goal we chose a novel photo-structurable polymer host-guest-system consisting of SU8 and a low refractive dopant monomer. Near and far-field measurements at different wavelengths show that the mode propagating within a well designed integrated waveguide structure and the mode of a standard fiber can exhibit a mode overlap value of approximately 1 and suffer only very low coupling losses. We demonstrate excess loss of 0.14 dB/cm for 808 nm, 0.33 dB/cm for 1310 nm and 2.86 dB/cm for 1550 nm. Typical insertion loss values of straight waveguides with a length of 36 mm are 0.9 dB for 808 nm, 1.5 dB for 1310 nm and 10.4 dB for 1550 nm. Polarization dependent loss was found to be less than 0.2 dB on sets of test structures of 36 mm length. We measured material attenuation in the novel polymer material before cross-linking of approximately 0.04 dB/cm for 808 nm and around 0.20 dB/cm for 1310 nm respectively. The presented production technique is suitable to provide low loss and low cost integrated optical circuits for sensor and communication applications in a broad wavelength range.

  4. Zero-mode waveguide nanophotonic structures for single molecule characterization

    Science.gov (United States)

    Crouch, Garrison M.; Han, Donghoon; Bohn, Paul W.

    2018-05-01

    Single-molecule characterization has become a crucial research tool in the chemical and life sciences, but limitations, such as limited concentration range, inability to control molecular distributions in space, and intrinsic phenomena, such as photobleaching, present significant challenges. Recent developments in non-classical optics and nanophotonics offer promising routes to mitigating these restrictions, such that even low affinity (K D ~ mM) biomolecular interactions can be studied. Here we introduce and review specific nanophotonic devices used to support single molecule studies. Optical nanostructures, such as zero-mode waveguides (ZMWs), are usually fabricated in thin gold or aluminum films and serve to confine the observation volume of optical microspectroscopy to attoliter to zeptoliter volumes. These simple nanostructures allow individual molecules to be isolated for optical and electrochemical analysis, even when the molecules of interest are present at high concentration (µM–mM) in bulk solution. Arrays of ZMWs may be combined with optical probes such as single molecule fluorescence, single molecule fluorescence resonance energy transfer, and fluorescence correlation spectroscopy for distributed analysis of large numbers of single-molecule reactions or binding events in parallel. Furthermore, ZMWs may be used as multifunctional devices, for example by combining optical and electrochemical functions in a single discrete architecture to achieve electrochemical ZMWs. In this review, we will describe the optical properties, fabrication, and applications of ZMWs for single-molecule studies, as well as the integration of ZMWs into systems for chemical and biochemical analysis.

  5. Stable Single-Mode Operation of Distributed Feedback Quantum Cascade Laser by Optimized Reflectivity Facet Coatings

    Science.gov (United States)

    Wang, Dong-Bo; Zhang, Jin-Chuan; Cheng, Feng-Min; Zhao, Yue; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2018-02-01

    In this work, quantum cascade lasers (QCLs) based on strain compensation combined with two-phonon resonance design are presented. Distributed feedback (DFB) laser emitting at 4.76 μm was fabricated through a standard buried first-order grating and buried heterostructure (BH) processing. Stable single-mode emission is achieved under all injection currents and temperature conditions without any mode hop by the optimized antireflection (AR) coating on the front facet. The AR coating consists of a double layer dielectric of Al2O3 and Ge. For a 2-mm laser cavity, the maximum output power of the AR-coated DFB-QCL was more than 170 mW at 20 °C with a high wall-plug efficiency (WPE) of 4.7% in a continuous-wave (CW) mode.

  6. Piezoelectric transducer parameter selection for exciting a single mode from multiple modes of Lamb waves

    International Nuclear Information System (INIS)

    Zhang Hai-Yan; Yu Jian-Bo

    2011-01-01

    Excitation and propagation of Lamb waves by using rectangular and circular piezoelectric transducers surface-bonded to an isotropic plate are investigated in this work. Analytical stain wave solutions are derived for the two transducer shapes, giving the responses of these transducers in Lamb wave fields. The analytical study is supported by a numerical simulation using the finite element method. Symmetric and antisymmetric components in the wave propagation responses are inspected in detail with respect to test parameters such as the transducer geometry, the length and the excitation frequency. By placing only one piezoelectric transducer on the top or the bottom surface of the plate and weakening the strength of one mode while enhancing the strength of the other modes to find the centre frequency, with which the peak wave amplitude ratio between the S0 and A0 modes is maximum, a single mode excitation from the multiple modes of the Lamb waves can be achieved approximately. Experimental data are presented to show the validity of the analyses. The results are used to optimize the Lamb wave detection system. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  7. Field emission from a single nanomechanical pillar

    International Nuclear Information System (INIS)

    Kim, Hyun S; Qin Hua; Westphall, Michael S; Smith, Lloyd M; Blick, Robert H

    2007-01-01

    We measured field emission from a silicon nanopillar mechanically oscillating between two electrodes. The pillar has a height of about 200 nm and a diameter of 50 nm, allowing resonant mechanical excitations at radio frequencies. The tunnelling barriers for field emission are mechanically modulated via displacement of the gold island on top of the pillar. We present a rich frequency-dependent response of the emission current in the frequency range of 300-400 MHz at room temperature. Modified Fowler-Nordheim field emission is observed and attributed to the mechanical oscillations of the nanopillar

  8. Single-photon emission tomography and cerebral blood flow

    International Nuclear Information System (INIS)

    Celsis, P.; Chan, M.; Marc-Vergnes, J.P.; Sveinsdottir, E.; Goldman, T.G.; Henriksen, L.; Paulson, O.B.; Stokely, E.M.; Lassen, N.A.

    1982-01-01

    This paper illustrates the capabilities of single-photon emission tomography in imaging local cerebral blood flows in man. The results purport the conclusion that a fairly good improvement has been achieved when compared to stationary detectors and that single-photon emission tomography is a well-suited tool for studying cerebral hemodynamics, especially within the framework of clinical studies [fr

  9. Nonlinear polarization effects in a birefringent single mode optical fiber

    International Nuclear Information System (INIS)

    Ishiekwene, G.C.; Mensah, S.Y.; Brown, C.S.

    2001-04-01

    The nonlinear polarization effects in a birefringent single mode optical fiber is studied using Jacobi elliptic functions. We find that the polarization state of the propagating beam depends on the initial polarization as well as the intensity of the input light in a complicated way. The Stokes polarization parameters are either periodic or aperiodic depending on the value of the Jacobian modulus. Our calculations suggest that the effective beat length of the fiber can become infinite at a higher critical value of the input power when polarization dependent losses are considered. (author)

  10. Mid-Infrared Continuously Tunable Single Mode VECSEL

    Science.gov (United States)

    Khiar, A.; Rahim, M.; Felder, F.; Fill, M.; Zogg, H.

    2011-12-01

    Tunable mid-infrared vertical external cavity surface emitting lasers were developed for the wavelength range around 3.8-3.9 μm and 3.2-3.3 μm, respectively. The devices are based on lead salt materials epitaxially grown by MBE on a Si substrate. The active part consists of PbSe QW in a PbSrSe host layer. Both devices are operated around -20 °C and have output power of several 10 mW. By changing the cavity length, a single mode hop free tuning range up to 80 cm-1 is achieved.

  11. Enhancement of mode-converted electron Bernstein wave emission during National Spherical Torus Experiment H-mode plasmas

    International Nuclear Information System (INIS)

    Taylor, G.; Efthimion, P.C.; Jones, B.; Le Blanc, B.P.; Maingi, R.

    2002-01-01

    A sudden, threefold increase in emission from fundamental electrostatic electron Bernstein waves (EBW) which mode convert and tunnel to the electromagnetic X-mode has been observed during high energy and particle confinement (H-mode) transitions in the National Spherical Torus Experiment (NSTX) plasma [M. Ono, S. Kaye, M. Peng et al., in Proceedings of the 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol. 3, p. 1135]. The mode-converted EBW emission viewed normal to the magnetic field on the plasma midplane increases when the density profile steepens in the vicinity of the mode conversion layer, which is located in the plasma scrape off. The measured conversion efficiency during the H-mode is consistent with the calculated EBW to X-mode conversion efficiency derived using edge density data. Calculations indicate that there may also be a small residual contribution to the measured X-mode electromagnetic radiation from polarization-scrambled, O-mode emission, converted from EBWs

  12. Single-transverse-mode near-IR superluminescent diodes with cw output power up to 100 mW

    International Nuclear Information System (INIS)

    Andreeva, E V; Il'chenko, S N; Kostin, Yu O; Yakubovich, S D

    2014-01-01

    A series of light-emitting modules based on single-mode quantum-well superluminescent diodes with centre emission wavelengths of about 790, 840, 960 and 1060 nm and a cw output power up to 100 mW in free space is developed. A sufficiently long service life of these devices is demonstrated. (lasers)

  13. Single-transverse-mode near-IR superluminescent diodes with cw output power up to 100 mW

    Energy Technology Data Exchange (ETDEWEB)

    Andreeva, E V; Il' chenko, S N; Kostin, Yu O [Superlum Diodes Ltd., Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2014-10-29

    A series of light-emitting modules based on single-mode quantum-well superluminescent diodes with centre emission wavelengths of about 790, 840, 960 and 1060 nm and a cw output power up to 100 mW in free space is developed. A sufficiently long service life of these devices is demonstrated. (lasers)

  14. Optically pumped semiconductor lasers: Conception and characterization of a single mode source for Cesium atoms manipulation

    International Nuclear Information System (INIS)

    Cocquelin, B.

    2009-02-01

    Lasers currently used in atomic clocks or inertial sensors are suffering from a lack of power, narrow linewidth or compactness for future spatial missions. Optically pumped semiconductor lasers, which combine the approach of classical solid state lasers and the engineering of semiconductor laser, are considered here as a candidate to a metrological laser source dedicated to the manipulation of Cesium atoms in these instruments. These lasers have demonstrated high power laser emission in a circular single transverse mode, as well as single longitudinal mode emission, favoured by the semiconductor structure and the external cavity design. We study the definition and the characterization of a proper semiconductor structure for the cooling and the detection of Cesium atoms at 852 nm. A compact and robust prototype tunable on the Cesium D2 hyperfine structure is built. The laser frequency is locked to an atomic transition thanks to a saturated absorption setup. The emission spectral properties are investigated, with a particular attention to the laser frequency noise and the laser linewidth. Finally, we describe and model the thermal properties of the semiconductor structure, which enables the simulation of the laser power characteristic. The experimental parameters are optimised to obtain the maximum output power with our structure. Thanks to our analysis, we propose several ways to overcome these limitations, by reducing the structure heating. (authors)

  15. Coupled-Mode Theory derivation of the formal equivalence between a three-mode waveguide and a set of three mutually coupled single-mode waveguides

    Directory of Open Access Journals (Sweden)

    Boucher Yann G.

    2017-01-01

    Full Text Available The formal identification between a two-mode waveguide and a system of two mutually coupled single-mode waveguides stems from the symmetries of the evolution operator. When the gap tends to zero, the super-modes of the coupled system merge continuously into the modes of the multimode waveguide. For modelling purposes, it is very tempting to extend the analogy to three-mode waveguides (and beyond. But not without some precautions…

  16. Pulse Propagation in Presence of Polarization Mode Dispersion and Chromatic Dispersion in Single Mode Fibers

    Directory of Open Access Journals (Sweden)

    Hassan Abid Yasser

    2013-01-01

    Full Text Available The presence of (first and second orders polarization mode dispersion (PMD, chromatic dispersion, and initial chirp makes effects on the propagated pulses in single mode fiber. Nowadays, there is not an accurate mathematical formula that describes the pulse shape in the presence of these effects. In this work, a theoretical study is introduced to derive a generalized formula. This formula is exactly approached to mathematical relations used in their special cases. The presence of second-order PMD (SOPMD will not affect the orthogonality property between the principal states of polarization. The simulation results explain that the interaction of the SOPMD components with the conventional effects (chromatic dispersion and chirp will cause a broadening/narrowing and shape distortion. This changes depend on the specified values of SOPMD components as well as the present conventional parameters.

  17. Single-mode regime in large-mode-area rare-earth-doped rod-type PCFs

    DEFF Research Database (Denmark)

    Poli, F.; Cucinotta, A.; Passaro, D.

    2009-01-01

    In this paper, large-mode-area, double-cladding, rare-earth-doped photonic crystal fibers are investigated in order to understand how the refractive index distribution and the mode competition given by the amplification can assure single-mode propagation. Fibers with different core diameters, i...

  18. Mid-infrared performance of single mode chalcogenide fibers

    Science.gov (United States)

    Cook, Justin; Sincore, Alex; Tan, Felix; El Halawany, Ahmed; Riggins, Anthony; Shah, Lawrence; Abouraddy, Ayman F.; Richardson, Martin C.; Schepler, Kenneth L.

    2018-02-01

    Due to the intrinsic absorption edge in silica near 2.4 μm, more exotic materials are required to transmit laser power in the IR such as fluoride or chalcogenide glasses (ChGs). In particular, ChG fibers offer broad IR transmission with low losses fibers at four different infrared wavelengths: 2053 nm, 2520 nm and 4550 nm. Polymer clad ChG fibers were drawn with 12.3 μm and 25 μm core diameters. Testing at 2053 nm was accomplished using a > 15 W, CW Tm:fiber laser. Power handling up to 10.2 W with single mode beam quality has been demonstrated, limited only by the available Tm:fiber output power. Anti-reflective coatings were successfully deposited on the ChG fiber facets, allowing up to 90.6% transmission with 12.2 MW/cm2 intensity on the facet. Single mode guidance at 4550 nm was also demonstrated using a quantum cascade laser (QCL). A custom optical system was constructed to efficiently couple the 0.8 NA QCL radiation into the 0.2 NA ChG fiber, allowing for a maximum of 78% overlap between the QCL radiation and fundamental mode of the fiber. With an AR-coated, 25 μm core diameter fiber, >50 mW transmission was demonstrated with > 87% transmission. Finally, we present results on fiber coupling from a free space Cr:ZnSe resonator at 2520 nm.

  19. Electron-cyclotron maser emission during flares: emission in various modes and temporal variations

    International Nuclear Information System (INIS)

    Winglee, R.M.; Dulk, G.A.

    1986-01-01

    Absorption of radiation at the electron-cyclotron frequency, OMEGA sub e, generated by the electron-cyclotron maser instability was proposed as a possible mechanism for transporting energy and heating of the corona during flares. Radiation from the same instability but at harmonics of OMEGA sub e is believed to be the source of solar microwave spike bursts. The actual mode and frequency of the dominant emission from the maser instability is shown to be dependent on: (1) the plasma temperature, (2) the form of the energetic electron distribution, and (3) on the ratio of the plasma frequency omega sub p to OMEGA sub e. As a result, the emission along a flux tube can vary, with emission at harmonics being favored in regions where omega sub p/OMEGA sub e approx. equal to or greater than 1. Changes in the plasma density and temperature in the source region associated with the flare can also cause the characteristics of the emission to change in time

  20. Demonstration of orbital angular momentum (OAM) modes emission from a silicon photonic integrated device for 20 Gbit/s QPSK carrying data transmission in few-mode fiber

    DEFF Research Database (Denmark)

    Liu, Jun; Li, Shimao; Ding, Yunhong

    2016-01-01

    We experimentally demonstrate orbital angular momentum (OAM) mode emission from a high emission efficiency OAM emitter for 20 Gbit/s QPSK carrying data transmission in few-mode fiber (FMF). Two modes propagate through a 3.6km three-mode FMF with measured OSNR penalties less than 4 dB at a BER of 2e...

  1. Non-Markovian spontaneous emission from a single quantum dot

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg; Ates, Serkan; Lund-Hansen, Toke

    2011-01-01

    We observe non-Markovian dynamics of a single quantum dot when tuned into resonance with a cavity mode. Excellent agreement between experiment and theory is observed providing the first quantitative description of such a system.......We observe non-Markovian dynamics of a single quantum dot when tuned into resonance with a cavity mode. Excellent agreement between experiment and theory is observed providing the first quantitative description of such a system....

  2. 3-4.5 μm continuously tunable single mode VECSEL

    Science.gov (United States)

    Fill, M.; Felder, F.; Rahim, M.; Khiar, A.; Zogg, H.

    2012-11-01

    We present continuously tunable Vertical External Cavity Surface Emitting Lasers (VECSEL) in the mid-infrared. The structure based on IV-VI semiconductors is epitaxially grown on a Si-substrates. The VECSEL emit one single mode, which is mode hop-free tunable over 50-100 nm around the center wavelength. In this work, two different devices are presented, emitting at 3.4 μm and 3.9 μm, respectively. The lasers operate near room temperature with thermoelectric stabilization. They are optically pumped, yielding an output power >10 mWp. The axial symmetric emission beam has a half divergence angle of <3.3∘.

  3. Quench Propagation Ignition using Single-Mode Diode Laser

    CERN Document Server

    Trillaud, F; Devred, Arnaud; Fratini, M; Leboeuf, D; Tixador, P

    2005-01-01

    The stability of NbTi-based multifilamentary composite wires subjected to local heat disturbances of short durations is studied in pool boiling helium conditions. A new type of heater is being developed to characterize the superconducting to normal state transition. It relies on a single-mode Diode Laser with an optical fiber illuminating the wire surface. This first paper focuses mainly on the feasibility of this new heater technology and eventually discusses the difficulties related to it. A small overview of Diode Lasers and optical fibers revolving around our application is given. Then, we describe the experimental setup, and present some recorded voltage traces of transition and recovery processes. In addition, we present also some energy and Normal Zone Propagation Velocity data and we outline ameliorations that will be done to the system.

  4. Picosecond chirped pulse compression in single-mode fibers

    International Nuclear Information System (INIS)

    Wenhua Cao; Youwei Zhang

    1995-01-01

    In this paper, the nonlinear propagation of picosecond chirped pulses in single mode fibers has been investigated both analytically and numerically. Results show that downchirped pulses can be compressed owing to normal group-velocity dispersion. The compression ratio depends both on the initial peak power and on the initial frequency chirp of the input pulse. While the compression ratio depends both on the initial peak power and on the initial frequency chirp of the input pulse. While the compression ratio increases with the negative frequency chirp, it decreases with the initial peak power of the input pulse. This means that the self-phase modulation induced nonlinear frequency chirp which is linear and positive (up-chirp) over a large central region of the pulse and tends to cancel the initial negative chirp of the pulse. It is also shown that, as the negative chirped pulse compresses temporally, it synchronously experiences a spectral narrowing

  5. Current measurements by Faraday rotation in single mode optical fibers

    International Nuclear Information System (INIS)

    Chandler, G.I.; Jahoda, F.C.

    1984-01-01

    Development of techniques for measuring magnetic fields and currents by Faraday rotation in single-mode optical fibers has continued. We summarize the results of attempts to measure the toroidal plasma current in the ZT-40 Reversed-Field-Pinch using multi-turn fiber coils. The fiber response is reproducible and in accord with theory, but the amount and distribution of the stress-induced birefringence in this case are such that prediction of the sensor response at low currents is difficult if not impossible. The low-current difficulty can be overcome by twisting the fiber to induce a circular birefringence bias. We report the results of auxiliary experiments with a fiber that has been twisted with 15 turns per meter and then re-coated to lock the twist in place

  6. Zero-phonon-line emission of single molecules for applications in quantum information processing

    Science.gov (United States)

    Kiraz, Alper; Ehrl, M.; Mustecaplioglu, O. E.; Hellerer, T.; Brauchle, C.; Zumbusch, A.

    2005-07-01

    A single photon source which generates transform limited single photons is highly desirable for applications in quantum optics. Transform limited emission guarantees the indistinguishability of the emitted single photons. This, in turn brings groundbreaking applications in linear optics quantum information processing within an experimental reach. Recently, self-assembled InAs quantum dots and trapped atoms have successfully been demonstrated as such sources for highly indistinguishable single photons. Here, we demonstrate that nearly transform limited zero-phonon-line (ZPL) emission from single molecules can be obtained by using vibronic excitation. Furthermore we report the results of coincidence detection experiments at the output of a Michelson-type interferometer. These experiments reveal Hong-Ou-Mandel correlations as a proof of the indistinguishability of the single photons emitted consecutively from a single molecule. Therefore, single molecules constitute an attractive alternative to single InAs quantum dots and trapped atoms for applications in linear optics quantum information processing. Experiments were performed with a home-built confocal microscope keeping the sample in a superfluid liquid Helium bath at 1.4K. We investigated terrylenediimide (TDI) molecules highly diluted in hexadecane (Shpol'skii matrix). A continuous wave single mode dye laser was used for excitation of vibronic transitions of individual molecules. From the integral fluorescence, the ZPL of single molecules was selected with a spectrally narrow interference filter. The ZPL emission was then sent to a scanning Fabry-Perot interferometer for linewidth measurements or a Michelson-type interferometer for coincidence detection.

  7. Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern

    DEFF Research Database (Denmark)

    Schunk, Gerhard; Fuerst, Josef U.; Förtsch, Michael

    2014-01-01

    Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMR...

  8. Emissions from Ethanol-Gasoline Blends: A Single Particle Perspective

    Directory of Open Access Journals (Sweden)

    Peter H. McMurry

    2011-06-01

    Full Text Available Due to its agricultural origin and function as a fuel oxygenate, ethanol is being promoted as an alternative biomass-based fuel for use in spark ignition engines, with mandates for its use at state and regional levels. While it has been established that the addition of ethanol to a fuel reduces the particulate mass concentration in the exhaust, little attention has been paid to changes in the physicochemical properties of the emitted particles. In this work, a dynamometer-mounted GM Quad-4 spark ignition engine run without aftertreatment at 1,500 RPM and 100% load was used with four different fuel blends, containing 0, 20, 40 and 85 percent ethanol in gasoline. This allowed the effects of the fuel composition to be isolated from other effects. Instrumentation employed included two Aerosol Time-of-Flight Mass Spectrometers covering different size ranges for analysis of single particle composition, an Aethalometer for black carbon, a Scanning Mobility Particle Sizer for particle size distributions, a Photoelectric Aerosol Sensor for particle-bound polycyclic aromatic hydrocarbon (PAH species and gravimetric filter measurements for particulate mass concentrations. It was found that, under the conditions investigated here, additional ethanol content in the fuel changes the particle size distribution, especially in the accumulation mode, and decreases the black carbon and total particulate mass concentrations. The molecular weight distribution of the PAHs was found to decrease with added ethanol. However, PAHs produced from higher ethanol-content fuels are associated with NO2− (m/z—46 in the single-particle mass spectra, indicating the presence of nitro-PAHs. Compounds associated with the gasoline (e.g., sulfur-containing species are diminished due to dilution as ethanol is added to the fuel relative to those associated with the lubricating oil (e.g., calcium, zinc, phosphate in the single particle spectra. These changes have potential

  9. Fracto-emission from single fibres of Kevlar

    Science.gov (United States)

    Dickinson, J. T.; Jahan-Latibari, A.; Jensen, L. C.

    1985-01-01

    Fracto-emission (FE) is the emission of particles (e.g. electrons, ions and photons) during and following fracture. In this paper, we present data on electron emission (EE) and positive ion emission (PIE) from the tensile fracture of Kevlar single fibers. The fibers were initially fractured in pure tension, where a stranded form of fracture was observed, often with multiple peaks spread over several hundred microseconds. The loading condition was then changed by stretching and breaking the fibers over a dull metal edge. With this change in the loading, different forms of fracture were observed, each with distinctive forms of emission curves. When fracture was accompanied by extensive fibril formation, total emission was high and both EE and PIE decay times were long relative to fractures in which little fibril formation occurred. The results of this study suggest that FE has some applicability as a tool for the detection of fracture mechanisms of single fibers.

  10. GaSb-based single-mode distributed feedback lasers for sensing (Conference Presentation)

    Science.gov (United States)

    Gupta, James A.; Bezinger, Andrew; Lapointe, Jean; Poitras, Daniel; Aers, Geof C.

    2017-02-01

    GaSb-based tunable single-mode diode lasers can enable rapid, highly-selective and highly-sensitive absorption spectroscopy systems for gas sensing. In this work, single-mode distributed feedback (DFB) laser diodes were developed for the detection of various trace gases in the 2-3.3um range, including CO2, CO, HF, H2S, H2O and CH4. The lasers were fabricated using an index-coupled grating process without epitaxial regrowth, making the process significantly less expensive than conventional DFB fabrication. The devices are based on InGaAsSb/AlGaAsSb separate confinement heterostructures grown on GaSb by molecular beam epitaxy. DFB lasers were produced using a two step etch process. Narrow ridge waveguides were first defined by optical lithography and etched into the semiconductor. Lateral gratings were then defined on both sides of the ridge using electron-beam lithography and etched to produce the index-grating. Effective index modeling was used to optimize the ridge width, etch depths and the grating pitch to ensure single-lateral-mode operation and adequate coupling strength. The effective index method was further used to simulate the DFB laser emission spectrum, based on a transfer matrix model for light transmission through the periodic structure. The fabricated lasers exhibit single-mode operation which is tunable through the absorption features of the various target gases by adjustment of the drive current. In addition to the established open-path sensing applications, these devices have great potential for optoelectronic integrated gas sensors, making use of integrated photodetectors and possibly on-chip Si photonics waveguide structures.

  11. Switching transport modes to meet voluntary carbon emission targets

    NARCIS (Netherlands)

    Hoen, K.M.R.; Tan, T.; Fransoo, J.C.; Houtum, van G.J.J.A.N.

    2014-01-01

    The transport sector is the second largest carbon emissions contributor in Europe and its emissions continue to increase. Many producers are committing themselves to reducing transport emissions voluntarily, possibly in anticipation of increasing transport prices. In this paper we study a producer

  12. Switching transport modes to meet voluntary carbon emission targets

    NARCIS (Netherlands)

    Hoen, K.M.R.; Tan, T.; Fransoo, J.C.; Houtum, van G.J.J.A.N.

    2011-01-01

    The transport sector is the second largest carbon emissions contributor in Europe and its emissions continue to increase. Many shippers are committing themselves to reducing transport emissions voluntarily, possibly in anticipation of increasing transport prices. In this paper we study a shipper

  13. Combustion Mode Design with High Efficiency and Low Emissions Controlled by Mixtures Stratification and Fuel Reactivity

    Directory of Open Access Journals (Sweden)

    Hu eWang

    2015-08-01

    Full Text Available This paper presents a review on the combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixture stratification that have been conducted in the authors’ group, including the charge reactivity controlled homogeneous charge compression ignition (HCCI combustion, stratification controlled premixed charge compression ignition (PCCI combustion, and dual-fuel combustion concepts controlled by both fuel reactivity and mixture stratification. The review starts with the charge reactivity controlled HCCI combustion, and the works on HCCI fuelled with both high cetane number fuels, such as DME and n-heptane, and high octane number fuels, such as methanol, natural gas, gasoline and mixtures of gasoline/alcohols, are reviewed and discussed. Since single fuel cannot meet the reactivity requirements under different loads to control the combustion process, the studies related to concentration stratification and dual-fuel charge reactivity controlled HCCI combustion are then presented, which have been shown to have the potential to achieve effective combustion control. The efforts of using both mixture and thermal stratifications to achieve the auto-ignition and combustion control are also discussed. Thereafter, both charge reactivity and mixture stratification are then applied to control the combustion process. The potential and capability of thermal-atmosphere controlled compound combustion mode and dual-fuel reactivity controlled compression ignition (RCCI/highly premixed charge combustion (HPCC mode to achieve clean and high efficiency combustion are then presented and discussed. Based on these results and discussions, combustion mode design with high efficiency and low emissions controlled by fuel reactivity and mixtures stratification in the whole operating range is proposed.

  14. Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern.

    Science.gov (United States)

    Schunk, Gerhard; Fürst, Josef U; Förtsch, Michael; Strekalov, Dmitry V; Vogl, Ulrich; Sedlmeir, Florian; Schwefel, Harald G L; Leuchs, Gerd; Marquardt, Christoph

    2014-12-15

    Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMRs. The radial mode numbers q and the angular mode numbers p = ℓ-m are identified and labeled via far-field imaging. The polar mode numbers ℓ are determined unambiguously by fitting the frequency differences between individual whispering gallery modes (WGMs). This allows for the accurate determination of the geometry and the refractive index at different temperatures of the WGMR. For future applications in classical and quantum optics, this mode analysis enables one to control the narrow-band phase-matching conditions in nonlinear processes such as second-harmonic generation or parametric down-conversion.

  15. DBD plasma source operated in single-filamentary mode for therapeutic use in dermatology

    Energy Technology Data Exchange (ETDEWEB)

    Rajasekaran, Priyadarshini; Mertmann, Philipp; Bibinov, Nikita; Awakowicz, Peter [Institute for Electrical Engineering and Plasma Technology, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44801 Bochum (Germany); Wandke, Dirk [CINOGY GmbH, Max-Naeder-Str. 15, 37114 Duderstadt (Germany); Vioel, Wolfgang, E-mail: rajasekaran@aept.rub.d, E-mail: mertmann@aept.rub.d, E-mail: Nikita.Bibinov@rub.d, E-mail: dirk.wandke@cinogy.co, E-mail: vioel@hawk-hhg.d, E-mail: awakowicz@aept.rub.d [University of Applied Sciences and Arts, Faculty of Natural Sciences and Technology, Von-Ossietzky-Str. 99, 37085 Goettingen (Germany)

    2009-11-21

    Our dielectric barrier discharge (DBD) plasma source for bio-medical application comprises a copper electrode covered with ceramic. Objects of high capacitance such as the human body can be used as the opposite electrode. In this study, the DBD source is operated in single-filamentary mode using an aluminium spike as the opposite electrode, to imitate the conditions when the discharge is ignited on a raised point, such as hair, during therapeutic use on the human body. The single-filamentary discharge thus obtained is characterized using optical emission spectroscopy, numerical simulation, voltage-current measurements and microphotography. For characterization of the discharge, averaged plasma parameters such as electron distribution function and electron density are determined. Fluxes of nitric oxide (NO), ozone (O{sub 3}) and photons reaching the treated surface are simulated. The calculated fluxes are finally compared with corresponding fluxes used in different bio-medical applications.

  16. Directional emission of single photons from small atomic samples

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; V. Poulsen, Uffe; Mølmer, Klaus

    2013-01-01

    We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state i...... is coupled by a classical laser field to an optically excited state which rapidly decays to the ground atomic state. Our model accounts for the different field polarization components via re-absorption and emission of light by the Zeeman manifold of optically excited states.......We provide a formalism to describe deterministic emission of single photons with tailored spatial and temporal profiles from a regular array of multi-level atoms. We assume that a single collective excitation is initially shared by all the atoms in a metastable atomic state, and that this state...

  17. Radiation resistance characteristics of optical communication system for single mode

    International Nuclear Information System (INIS)

    Ohe, Masamoto; Chigusa, Yoshiki; Kyodo, Tomohisa; Tanaka, Gohtaro; Watanabe, Hajime; Okamoto, Shin-ichi; Yamamoto, Takao.

    1988-01-01

    Optical communication has been utilized also for nuclear power stations and fuel reporocessing plants. As the sufficient safety countermeasures are required there, the amount of information becomes enormous, therefore, optical communication, by which the required space is expected to be reduced, becomes more important. Also in the application to submarine cables, attention must be paid to the radiation resistance as there are the effects of potassium contained in large amount in seawater and uranium deposits in sea bottom. Therefore, the reliability of the components of optical communication systems against radiation becomes a problem. In this study, single mode optical fibers and transmission and receipt modules were selected, and high dose rate irradiation supposing the case of using in a cell and low dose rate, long time irradiation supposing the case of submarine cables were carried out to evaluate the radiation resistance characteristics. The fibers tested were SiO 2 core/F-SiO 2 clad type and GeO 2 -SiO 2 core/SiO 2 clad type. The characteristics of increasing loss in irradiation and restoration after irradiation of the former type were superior to those of the latter type. The output of a receipt module was normal during irradiation, and the output power of a transmission module decreases, but other problems did not arise. (K.I.)

  18. Modeling bidirectionally coupled single-mode semiconductor lasers

    International Nuclear Information System (INIS)

    Mulet, Josep; Masoller, Cristina; Mirasso, Claudio R.

    2002-01-01

    We develop a dynamical model suitable for the description of two mutually coupled semiconductor lasers in a face-to-face configuration. Our study considers the propagation of the electric field along the compound system as well as the evolution of the carrier densities within each semiconductor laser. Mutual injection, passive optical feedback, and multiple reflections are accounted for in this framework, although under weak to moderate coupling conditions. We systematically describe the effect of the coupling strength on the spectrum of monochromatic solutions and on the respective dynamical behavior. By assuming single-longitudinal-mode operation, weak mutual coupling and slowly varying approximation, the dynamical model can be reduced to rate equations describing the mutual injection from one laser to its counterpart and vice versa. A good agreement between the complete and simplified models is found for small coupling. For larger coupling, higher-order terms lead to a smaller threshold reduction, reflected itself in the spectrum of the monochromatic solutions and in the dynamics of the optical power

  19. Effect of localized surface-plasmon mode on exciton transport and radiation emission in carbon nanotubes.

    Science.gov (United States)

    Roslyak, Oleksiy; Cherqui, Charles; Dunlap, David H; Piryatinski, Andrei

    2014-07-17

    We report on a general theoretical approach to study exciton transport and emission in a single-walled carbon nanotube (SWNT) in the presence of a localized surface-plasmon (SP) mode within a metal nanoparticle interacting via near-field coupling. We derive a set of quantum mechanical equations of motion and approximate rate equations that account for the exciton, SP, and the environmental degrees of freedom. The material equations are complemented by an expression for the radiated power that depends on the exciton and SP populations and coherences, allowing for an examination of the angular distribution of the emitted radiation that would be measured in experiment. Numerical simulations for a (6,5) SWNT and cone-shaped Ag metal tip (MT) have been performed using this methodology. Comparison with physical parameters shows that the near-field interaction between the exciton-SP occurs in a weak coupling regime, with the diffusion processes being much faster than the exciton-SP population exchange. In such a case, the effect of the exciton population transfer to the MT with its subsequent dissipation (i.e., the Förster energy transfer) is to modify the exciton steady state distribution while reducing the equilibration time for excitons to reach a steady sate distribution. We find that the radiation distribution is dominated by SP emission for a SWNT-MT separation of a few tens of nanometers due to the fast SP emission rate, whereas the exciton-SP coherences can cause its rotation.

  20. Estimating accidental coincidences for pixelated PET detectors and singles list-mode acquisition

    International Nuclear Information System (INIS)

    Rafecas, M.; Torres, I.; Spanoudaki, V.; McElroy, D.P.; Ziegler, S.I.

    2007-01-01

    We have studied the validity of random estimation techniques for various low energy thresholds (LETs) and single list-mode data sets in small animal PET. While a LET below 255 keV helps to increase the sensitivity, it also results in an increase of random coincidences and inter-crystal scatter (ICS). The study is carried out for MADPET-II, a dual-layer positron emission tomography (PET) scanner prototype consisting of LSO crystals read out individually by APDs. The data are acquired in singles list-mode format, and coincidences are computed post-acquisition. To estimate randoms, we have used the delayed coincidence window method (DW), and the singles rate model (SR). Various phantoms were simulated using GATE. For LETs under 255 keV, the number of random events R, estimated using the SR and the DW methods, is larger than the number of randoms which was directly computed from GATE simulations, and R(SR)>R(DW)>R(GATE). The higher the LET, the smaller the overestimation. For LETs >255 keV, R(DW)/R(GATE) ∼1. If scattered singles were excluded from the file, this discrepancy between R(DW or SR) and R(GATE) significantly diminished. This fact points out to ICS as the effect responsible for the mismatch, since for LETs lower than 255 keV, all singles related to an ICS event can be detected independently, thus altering the singles rate. Therefore, if low LETs are used, random estimation techniques should account for ICS

  1. Single photon emission computerized tomography (SPECT)

    International Nuclear Information System (INIS)

    Ganatra, R.D.

    1992-01-01

    Tomography in nuclear medicine did not originate after the introduction of X-ray computerized tomography (CT). Even in the days of rectilinear scanner, tomography was attempted with multiple detector heads rotating around the patient, but the counts at each plane were never very high to obtain a satisfactory image. A high resolution focusing collimator can look at different depths but taking several slices in one projection was a time consuming process. Rectilinear scanners lose lot of counts in the collimator to look at one point, at on time, in one plane. It is true that attempts to do tomography with gamma camera really got a boost after the success of CT. By that time, algorithms for doing reconstruction of images also were highly refined and for advanced. Clinical application of SPECT has become widespread now, because of the development of suitable radiopharmaceuticals and improvement in instrumentation. The SPECT provides a direct measure of regional organ function and is performed with nuclides such as 123 I and 99 Tc m that emit a mono-image photon during their decay. SPECT is far less expensive than positron emission tomography

  2. Single photon emission computerized tomography (SPECT)

    Energy Technology Data Exchange (ETDEWEB)

    Ganatra, R D

    1993-12-31

    Tomography in nuclear medicine did not originate after the introduction of X-ray computerized tomography (CT). Even in the days of rectilinear scanner, tomography was attempted with multiple detector heads rotating around the patient, but the counts at each plane were never very high to obtain a satisfactory image. A high resolution focusing collimator can look at different depths but taking several slices in one projection was a time consuming process. Rectilinear scanners lose lot of counts in the collimator to look at one point, at on time, in one plane. It is true that attempts to do tomography with gamma camera really got a boost after the success of CT. By that time, algorithms for doing reconstruction of images also were highly refined and for advanced. Clinical application of SPECT has become widespread now, because of the development of suitable radiopharmaceuticals and improvement in instrumentation. The SPECT provides a direct measure of regional organ function and is performed with nuclides such as {sup 123}I and {sup 99}Tc{sup m} that emit a mono-image photon during their decay. SPECT is far less expensive than positron emission tomography

  3. Strong diameter-dependence of nanowire emission coupled to waveguide modes

    Energy Technology Data Exchange (ETDEWEB)

    Dam, Dick van, E-mail: a.d.v.dam@tue.nl; Haverkort, Jos E. M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Abujetas, Diego R.; Sánchez-Gil, José A. [Instituto de Estructura de la Materia (IEM-CSIC), Consejo Superior de Investigaciones Científicas Serrano, 121, 28006 Madrid (Spain); Bakkers, Erik P. A. M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Gómez Rivas, Jaime, E-mail: j.gomezrivas@differ.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Dutch Institute for Fundamental Energy Research DIFFER, P.O. Box 6336, 5600 HH Eindhoven (Netherlands)

    2016-03-21

    The emission from nanowires can couple to waveguide modes supported by the nanowire geometry, thus governing the far-field angular pattern. To investigate the geometry-induced coupling of the emission to waveguide modes, we acquire Fourier microscopy images of the photoluminescence of nanowires with diameters ranging from 143 to 208 nm. From the investigated diameter range, we conclude that a few nanometers difference in diameter can abruptly change the coupling of the emission to a specific mode. Moreover, we observe a diameter-dependent width of the Gaussian-shaped angular pattern in the far-field emission. This dependence is understood in terms of interference of the guided modes, which emit at the end facets of the nanowire. Our results are important for the design of quantum emitters, solid state lighting, and photovoltaic devices based on nanowires.

  4. Single photon infrared emission spectroscopy: a study of IR emission from UV laser excited PAHs between 3 and 15 micrometers

    Science.gov (United States)

    Cook, D. J.; Schlemmer, S.; Balucani, N.; Wagner, D. R.; Harrison, J. A.; Steiner, B.; Saykally, R. J.

    1998-01-01

    Single-photon infrared emission spectroscopy (SPIRES) has been used to measure emission spectra from polycyclic aromatic hydrocarbons (PAHs). A supersonic free-jet expansion has been used to provide emission spectra of rotationally cold and vibrationally excited naphthalene and benzene. Under these conditions, the observed width of the 3.3-micrometers (C-H stretch) band resembles the bandwidths observed in experiments in which emission is observed from naphthalene with higher rotational energy. To obtain complete coverage of IR wavelengths relevant to the unidentified infrared bands (UIRs), UV laser-induced desorption was used to generate gas-phase highly excited PAHs. Lorentzian band shapes were convoluted with the monochromator-slit function in order to determine the widths of PAH emission bands under astrophysically relevant conditions. Bandwidths were also extracted from bands consisting of multiple normal modes blended together. These parameters are grouped according to the functional groups mostly involved in the vibration, and mean bandwidths are obtained. These bandwidths are larger than the widths of the corresponding UIR bands. However, when the comparison is limited to the largest PAHs studied, the bandwidths are slightly smaller than the corresponding UIR bands. These parameters can be used to model emission spectra from PAH cations and cations of larger PAHs, which are better candidate carriers of the UIRs.

  5. Investigation of single-mode and multi-mode hydromagnetic Rayleigh-Taylor instability in planar geometry

    International Nuclear Information System (INIS)

    Roderick, N.F.; Cochrane, K.; Douglas, M.R.

    1998-01-01

    Previous investigations carried out to study various methods of seeding the hydromagnetic Rayleigh-Taylor instability in magnetohydrodynamic simulations showed features similar to those seen in hydrodynamic calculations. For periodic single-mode initiations the results showed the appearance of harmonics as the single modes became nonlinear. For periodic multi-mode initiations new modes developed that indicated the presence of mode coupling. The MHD simulations used parameters of the high velocity large radius z-pinch experiments performed in the Z-accelerator at Sandia National Laboratories. The cylindrical convergent geometry and variable acceleration of these configurations made comparison with analytic, developed for planar geometry with constant acceleration, difficult. A set of calculations in planar geometry using constant current to produce acceleration and parameters characteristic of the cylindrical implosions has been performed to allow a better comparison. Results of these calculations, comparison with analytic theory, and comparison with the cylindrical configuration calculations will be discussed

  6. Broadband enhancement of single photon emission and polarization dependent coupling in silicon nitride waveguides.

    Science.gov (United States)

    Bisschop, Suzanne; Guille, Antoine; Van Thourhout, Dries; Hens, Zeger; Brainis, Edouard

    2015-06-01

    Single-photon (SP) sources are important for a number of optical quantum information processing applications. We study the possibility to integrate triggered solid-state SP emitters directly on a photonic chip. A major challenge consists in efficiently extracting their emission into a single guided mode. Using 3D finite-difference time-domain simulations, we investigate the SP emission from dipole-like nanometer-sized inclusions embedded into different silicon nitride (SiNx) photonic nanowire waveguide designs. We elucidate the effect of the geometry on the emission lifetime and the polarization of the emitted SP. The results show that highly efficient and polarized SP sources can be realized using suspended SiNx slot-waveguides. Combining this with the well-established CMOS-compatible processing technology, fully integrated and complex optical circuits for quantum optics experiments can be developed.

  7. Tripartite entanglement of bosonic systems in a noninertial frame beyond the single- mode approximation

    Directory of Open Access Journals (Sweden)

    M Soltani

    2015-12-01

    Full Text Available In this work, we generalize the entanglement of three-qbit Bosonic systems beyond the single-mode approximation when one of the observers is accelerated. For this purpose, we review the effects of acceleration on field modes and quantum states. The single-mode approximation and beyond the single-mode approximation methods are introduced. After this brief introduction, the main problem of this paper, tripartite entanglement of bosonic systems in a noninertial frame beyond the single- mode approximation is investigated. The tripartite entangled states have different classes with GHZ and W states being most important. Here, we choose &pi-tangle as a measure of tripartite entanglement. If the three parties share GHZ state, the corresponding &pi-tangle will increase by increasing acceleration for some Unruh modes. This phenomenon, increasing entanglement, has never been observed in the single-mode approximation for bosonic case. Moreover, the &pi-tangle dose not exhibit a monotonic behavior with increasing acceleration. In the infinite acceleration limit, the &pi-tangle goes to different nonzero values for distinct Unruh modes. Unlike GHZ state, the entanglement of the W state shows only monotonically increasing and decreasing behaviors with increasing acceleration. Also, the entanglement for all possible choices of Unruh modes approaches only 0.176 in the high acceleration limit. Therefore, according to the quantum entanglement, there is no distinction between the single-mode approximation and beyond the single-mode approximation methods in this limit.

  8. A scanner for single photon emission tomography

    International Nuclear Information System (INIS)

    Smith, D.B.; Cumpstey, D.E.; Evans, N.T.S.; Coleman, J.D.; Ettinger, K.V.; Mallard, J.R.

    1982-01-01

    The technique of single photon ECT has now been available for some eighteen years, but has yet still to be exploited fully. The difficulties of doing this lie in the need for gathering data of sufficiently good statistical accuracy in a reasonable counting time, in the uniformity of detector sensitivity, and in the means for correcting the image satisfactorily for photon attenuation within the body. The relative ease with which a general purpose gamma camera can be adapted to give rotation around the patient makes this an attractive practical approach to the problem. However, the sensitivity of gamma cameras over their field of view is by no means uniform, and their sensitivity is less good than that of purpose-designed scanners when no more than about ten sections through the body are required. There is therefore a need to assess the clinical usefulness of a whole body tomographic scanner of high sensitivity and uniformity. Such a machine is the Aberdeen Section Scanner Mark II described

  9. Control of Single Molecule Fluorescence Dynamics by Stimulated Emission Depletion

    OpenAIRE

    Marsh, R. J.; Osborne, M. A.; Bain, A. J.

    2003-01-01

    The feasibility of manipulating the single molecule absorption-emission cycle using picosecond stimulated emission depletion (STED) is investigated using a stochastic computer simulation. In the simulation the molecule is subjected to repeated excitation and depletion events using time delayed pairs of excitation (PUMP) and depletion (DUMP) pulses derived from a high repetition rate pulsed laser system. The model is used to demonstrate that a significant and even substantial reduction in the ...

  10. Diagnosis of dementia with single photon emission computed tomography

    International Nuclear Information System (INIS)

    Jagust, W.J.; Budinger, T.F.; Reed, B.R.

    1987-01-01

    Single photon emission computed tomography is a practical modality for the study of physiologic cerebral activity in vivo. We utilized single photon emission computed tomography and N-isopropyl-p-iodoamphetamine iodine 123 to evaluate regional cerebral blood flow in nine patients with Alzheimer's disease (AD), five healthy elderly control subjects, and two patients with multi-infarct dementia. We found that all subjects with AD demonstrated flow deficits in temporoparietal cortex bilaterally, and that the ratio of activity in bilateral temporoparietal cortex to activity in the whole slice allowed the differentiation of all patients with AD from both the controls and from the patients with multi-infarct dementia. Furthermore, this ratio showed a strong correlation with disease severity in the AD group. Single photon emission computed tomography appears to be useful in the differential diagnosis of dementia and reflects clinical features of the disease

  11. Detecting mode hopping in single-longitudinal-mode fiber ring lasers based on an unbalanced fiber Michelson interferometer.

    Science.gov (United States)

    Ma, Mingxiang; Hu, Zhengliang; Xu, Pan; Wang, Wei; Hu, Yongming

    2012-10-20

    A method of detecting mode hopping for single-longitudinal-mode (SLM) fiber ring lasers has been proposed and experimentally demonstrated. The method that is based on an unbalanced Michelson interferometer (MI) utilizing phase generated carrier modulation instantly transforms mode-hopping dynamics into steep phase changes of the interferometer. Multiform mode hops in an SLM erbium-doped fiber ring laser with an 18.6 MHz mode spacing have been detected exactly in real-time domain and discussed in detail. Numerical results show that the MI-based method has a high testing sensitivity for identifying mode hopping, which will play a significant role in evaluating the output stability of SLM fiber lasers.

  12. A narrow linewidth tunable single longitudinal mode Ga-EDF fiber laser

    Science.gov (United States)

    Mohamed Halip, N. H.; Abu Bakar, M. H.; Latif, A. A.; Muhd-Yasin, S. Z.; Zulkifli, M. I.; Mat-Sharif, K. A.; Omar, N. Y. M.; Mansoor, A.; Abdul-Rashid, H. A.; Mahdi, M. A.

    2018-05-01

    A tunable ring cavity single longitudinal mode (SLM) fiber laser incorporating Gallium-Erbium co-doped fiber (Ga-EDF) gain medium and several mode filtration techniques is demonstrated. With Ga-EDF, high emission power was accorded in short fiber length, allowing shorter overall cavity length and wider free spectral range. Tunable bandpass filter, sub-ring structure, and cascaded dissimilar fiber taper were utilized to filter multi-longitudinal modes. Each of the filter mechanism was tested individually within the laser cavity to assess its performance. Once the performance of each filter was obtained, all of them were deployed into the laser system. Ultimately, the 1561.47 nm SLM laser achieved a narrow linewidth laser, optical signal-to-noise ratio, and power fluctuation of 1.19 kHz, 61.52 dB and 0.16 dB, respectively. This work validates the feasibility of Ga-EDF to attain a stable SLM output in simple laser configuration.

  13. Low-bending loss and single-mode operation in few-mode optical fiber

    Science.gov (United States)

    Yin, Ping; Wang, Hua; Chen, Ming-Yang; Wei, Jin; Cai, Zhi-Min; Li, Lu-Ming; Yang, Ji-Hai; Zhu, Yuan-Feng

    2016-10-01

    The technique of eliminating the higher-order modes in a few-mode optical fiber is proposed. The fiber is designed with a group of defect modes in the cladding. The higher-order modes in the fiber can be eliminated by bending the fiber to induce strong coupling between the defect modes and the higher-order modes. Numerical simulation shows the bending losses of the LP01 mode are lower than 1.5×10-4 dB/turn for the wavelength shorter than 1.625 μm. The proposed fiber can be bent multiple turns at small bending radius which are preferable for FTTH related applications.

  14. Design of all solid state tunable single-mode Ti: sapphire laser for nuclear industry

    International Nuclear Information System (INIS)

    Lee, J.H.; Nam, S.M.; Lee, Y.J.; Lee, J.M.; Horn, Roland E.; Wendt, Klaus

    1999-01-01

    We designed a Ti:Sapphire laser pumped by a diode laser pumped solid state laser (DPSSL). The DPSSL was intra-cavity frequency doubled and it had 20 W output power. The Ti:Sapphire laser was designed for single longitudinal mode lasing. For single mode lasing, the laser used several solid etalons. We simulated temporal evolution of the laser pulse and single pass amplification rate of the photons in each modes from rate equations. From the result, we found that single mode lasing is viable in this cavity

  15. Investigation on utilization of biogas and Karanja oil biodiesel in dual fuel mode in a single cylinder DI diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    Prasanna Pattanaik, Bhabani; Nayak, Chandrakanta [Department of Mechanical Eng., Gandhi Institute for Technological Advancement, Madanpur, Bhubaneswar - 752054, Odisha (India); Kumar Nanda, Basanta [Department of Mechanical Eng., Maharaja Institute of Technology, Bhubaneswar, Odisha (India)

    2013-07-01

    In this work, experiments were performed on a single cylinder DI diesel engine by using bio-gas as a primary fuel and Karanja oil biodiesel and diesel oil as secondary fuels in dual fuel operation. The experiments were performed to measure performance parameters i.e. (brake specific fuel consumption, brake thermal efficiency and exhaust gas temperature) and emission parameters such as carbon monoxide, carbon dioxide, nitrogen oxide unburned hydro carbon and smoke etc. at different load conditions. For the dual-fuel system, the intake system of the test engine was modified to convert into biogas and biodiesel of a dual-fueled combustion engine. Biogas was injected during the intake process by gas injectors. The study showed that, the engine performance parameters like BP, BTE and EGT gradually increase with increase in engine load for all test conditions using both pilot fuels diesel and KOBD. However, the BSFC of the engine showed decreasing slope with increase in engine load for all test conditions. Above 40% engine load the BSFC values for all test fuels are very close to each other. The engine emission analysis showed that the CO2, CO and NOx emissions increase with increase in engine load for both single and dual fuel mode operation using both pilot fuels. The NOx concentration of exhaust gases in dual fuel mode is superior than that of single mode.

  16. Mode Engineering of Single Photons from Cavity Spontaneous Parametric Down-Conversion Source and Quantum Dots

    Science.gov (United States)

    Paudel, Uttam

    Over the past decade, much effort has been made in identifying and characterizing systems that can form a building block of quantum networks, among which semiconductor quantum dots (QD) and spontaneous parametric down-conversion (SPDC) source are two of the most promising candidates. The work presented in this thesis will be centered on investigating and engineering the mentioned systems for generating customizable single photons. A type-II SPDC source can generate a highly flexible pair of entangled photons that can be used to interface disparate quantum systems. In this thesis, we have successfully implemented a cavity-SPDC source that emits polarization correlated photons at 942 nm with a lifetime of 950-1050ps that mode matches closely with InAs/GaAs QD photons. The source emits 80 photon pairs per second per mW pump power within the 150MHz bandwidth. Though the detection of idler photons, the source is capable of emitting heralded photons with g2?0.5 for up to 40 mW pump power. For a low pump power of 5 mW, the heralded g2 is 0.06, indicating that the system is an excellent heralded single photon source. By directly exciting a single QD with cavity-SPDC photons, we have demonstrated a heralded-absorption of SPDC photons by QD, resulting in the coupling of the two systems. Due to the large pump bandwidth, the emitted source is highly multimode in nature, requiring us to post-filter the downconverted field, resulting in a lower photon pair emission rate. We propose placing an intra-cavity etalon to suppress the multi-mode emissions and increase the photon count rate. Understanding and experimentally implementing two-photon interference (HOM) measurements will be crucial for building a scalable quantum network. A detailed theoretical description of HOM measurements is given and is experimentally demonstrated using photons emitted by QD. Through HOM measurements we demonstrated that the QD sample in the study is capable of emitting indistinguishable photons, with

  17. Single-mode distributed feedback laser operation with no dependence on the morphology of the gain medium

    Energy Technology Data Exchange (ETDEWEB)

    Umar, Muhammad [Department of Energy Systems Research, Ajou University, Suwon (Korea, Republic of); Min, Kyungtaek [Department of Energy Systems Research, Ajou University, Suwon (Korea, Republic of); Inter-university Semiconductor Research Center, Seoul National University (Korea, Republic of); Jeon, Heonsu [Department of Physics and Astronomy, Seoul National University (Korea, Republic of); Kim, Sunghwan [Department of Energy Systems Research, Ajou University, Suwon (Korea, Republic of); Department of Physics, Ajou University, Suwon (Korea, Republic of)

    2017-06-15

    Organic distributed feedback (DFB) lasers can be useful photonic tools for biological applications where the roles of organic materials are important, because highly coherent single mode emission with broad tuning range can be obtained. However, the formulaic structures of organic lasers, and the uses of gain media as resonators themselves, are not suitable for inducing laser emission from irregular shaped gain media, such as dye-staining cells and tissues. Here, we report a reusable photonic template comprising an exceedingly thin and discrete titanium dioxide (TiO{sub 2}) layer on a one-dimensional (1D) quartz grating to induce single mode DFB lasing from a variety of states of optical gain media. Using the same template, the external gain media of optically thick and thin casted film, liquid, and a free-standing thick film reveal single mode lasing with reliable performance. Numerical simulations demonstrate that the 25-nm thick TiO{sub 2} disconnected grating lines support a spatially confined DFB mode in the vertical direction, even under no index difference between superstrate and substrate. Additionally, not using the typical waveguide gain layer promises high sensitivity and detection limit in refractometric sensing. These results suggest that the photonic structure may serve as a versatile sensing platform for bioapplications. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Multiparameter-dependent spontaneous emission in PbSe quantum dot-doped liquid-core multi-mode fiber

    International Nuclear Information System (INIS)

    Zhang, Lei; Zhang, Yu; Wu, Hua; Zhang, Tieqiang; Gu, Pengfei; Chu, Hairong; Cui, Tian; Wang, Yiding; Zhang, Hanzhuang; Zhao, Jun; Yu, William W.

    2013-01-01

    A theoretical model was established in this paper to analyze the properties of 3.50 and 4.39 nm PbSe quantum dot-doped liquid-core multi-mode fiber. This model was applicable to both single- and multi-mode fiber. The three-level system-based light-propagation equations and rate equations were used to calculate the guided spontaneous emission spectra. Considering the multi-mode in the fiber, the normalized intensity distribution of transversal model was improved and simplified. The detailed calculating results were thus obtained and explained using the above-mentioned model. The redshift of the peak position and the evolution of the emission power were observed and analyzed considering the influence of the fiber length, fiber diameter, doping concentration, and the pump power. The redshift increased with the increases of fiber length, fiber diameter, and doping concentration. The optimal fiber length, fiber diameter, and doping concentration were analyzed and confirmed, and the related spontaneous emission power was obtained. Besides, the normalized emission intensity increased with the increase of pump power in a nearly linear way. The calculating results fitted well to the experimental data

  19. Single-mode ytterbium-doped large-mode-area photonic bandgap rod fiber amplifier

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Scolari, Lara; Broeng, Jes

    2011-01-01

    bandgap structure. The structure allows resonant coupling of higher-order modes from the core and acts as a spatially Distributed Mode Filter (DMF). With this approach, we demonstrate passive SM performance in an only ~50cm long and straight ytterbium-doped rod fiber. The amplifier has a mode field...... diameter of ∼59Lim at 1064nm and exhibits a pump absorption of 27dB/m at 976nm. © 2011 Optical Society of America....

  20. Cyclotron absorption and emission in mode conversion layers emdash a new paradigm

    International Nuclear Information System (INIS)

    Swanson, D.G.

    1995-01-01

    When the analysis of absorption with mode conversion effects included began to mature in recent years, the study of the corresponding effects on emission began and has led to some surprising results. The classical expressions for cyclotron or synchrotron emission from a harmonic resonance were originally derived from models that did not include mode conversion or its attendant reflection, and classical expressions for the optical depth and opacity were obtained. When mode conversion was included, the principal surprise was that the transmission coefficient, which was understood as being due to absorption, is totally independent of absorption and due exclusively to tunneling. The other surprise from the mode conversion analysis is that the observed emission arises from two distinct sources, one direct and one from an indirect Bernstein wave source which is partially converted in the cyclotron layer to outgoing electromagnetic waves, with the net result that mode conversion cancels out for the electron case, but not for ions. The only corrections to electron cyclotron emission are then due to reflection effects, and these have been shown to be small for many laboratory plasmas, leading to the validation of the classical formula for these cases, but via an entirely new paradigm in its interpretation. This review includes a summary of the absorption process for both electron and ion cyclotron harmonics, and reviews carefully the emission physics, including both potential error estimates and a discussion of the emission source distribution in space

  1. Whispering gallery mode emission from a composite system of J-aggregates and photonic microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Melnikau, Dzmitry; Savateeva, Diana [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); Rusakov, Konstantin I. [Department of Physics, Brest State Technical University, Brest 224017 (Belarus); Rakovich, Yury P., E-mail: Yury.Rakovich@ehu.es [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)

    2014-01-15

    We report on development and characterization of Whispering Gallery Modes spherical microcavities integrated with organic dye molecules in a J-aggregate state. The microcavities are studied using micro-photoluminescence spectroscopy, and fluorescence lifetime imaging confocal microscopy. Directional emission of light from the microcavity is also experimentally demonstrated and attributed to the photonic jets generated in the microsphere. -- Highlights: • Report on the development and characterization of hybrid system consisting of thin shell of J-aggregates and spherical Whispering Gallery Mode microcavity. • An investigation of spontaneous emission rate in the shell of J-aggregates integrated with a Whispering Gallery Mode cavity. • Demonstration of directional emission from Whispering Gallery Mode cavity with J-aggregates which is highly desirable functionality for both micro- and nano-scale cavities.

  2. Startup methods for single-mode gyrotron operation

    International Nuclear Information System (INIS)

    Whaley, D.R.; Tran, M.Q.; Alberti, S.; Tran, T.M.; Antonsen, T.M. Jr.; Dubrovin, A.; Tran, C.

    1995-01-01

    Experimental results of startup studies on a 118 GHz TE 22,6 gyrotron are presented and compared with theory. The startup paths through the energy-velocity-pitch-angle plane are determined by the time evolution of the beam parameters during the startup phase. These startup paths are modified by changing the anode and cathode voltage rise from zero to their nominal values and are seen to determine the cavity oscillating mode. Experimental results show specifically that competition between the TE 22,6 and TE -19,7 mode can be completely eliminated by use of the proper startup method in a case where a typical triode startup results in oscillation in the competing TE -19,7 mode. These new results are shown to be in excellent agreement with the theory whose approach is general and therefore applicable to gyrotrons operating in any arbitrary cavity mode. (author) 3 figs., 4 refs

  3. High frequency single mode traveling wave structure for particle acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Ivanyan, M.I.; Danielyan, V.A.; Grigoryan, B.A.; Grigoryan, A.H. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Tsakanian, A.V. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Technische Universität Darmstadt, Institut TEMF, 64289 Darmstadt (Germany); Tsakanov, V.M., E-mail: tsakanov@asls.candle.am [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia); Vardanyan, A.S.; Zakaryan, S.V. [CANDLE Synchrotron Research Institute, 0040 Yerevan (Armenia)

    2016-09-01

    The development of the new high frequency slow traveling wave structures is one of the promising directions in accomplishment of charged particles high acceleration gradient. The disc and dielectric loaded structures are the most known structures with slowly propagating modes. In this paper a large aperture high frequency metallic two-layer accelerating structure is studied. The electrodynamical properties of the slowly propagating TM{sub 01} mode in a metallic tube with internally coated low conductive thin layer are examined.

  4. Zn doped GaN for single-photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Behrends, Arne; Ledig, Johannes; Al-Suleiman, Mohamed Aid Mansur; Bakin, Andrey; Waag, Andreas [Institute of Semiconductor Technology, University of Technology Braunschweig, Hans-Sommer-Str. 66, 38106 Braunschweig (Germany); Peters, Silke; Racu, Ana Maria; Schmunk, Waldemar; Hofer, Helmut; Kueck, Stefan [Physikalisch Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany)

    2012-03-15

    In this work we report on the optical investigation of Zn doped GaN films fabricated by metal organic chemical vapor deposition. The samples show bright emission in the blue spectral range around 2.9 eV when Si codoping is provided. This emission is suggested to be used for single-photon emission, thus the density of the Zn-Si pairs was drastically reduced leading to a decrease of the blue luminescence. For electrically excited single-photon sources these Zn-Si pairs have to be incorporated into LEDs, therefore we fabricated GaN-based nano-LEDs which show electroluminescence at 430 nm (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Startup methods for single-mode gyrotron operation

    International Nuclear Information System (INIS)

    Whaley, D.R.; Tran, M.Q.; Alberti, S.; Tran, T.M.; Antonsen, T.M.; Tran, C.

    1995-03-01

    Experimental results of startup studies on a 118 GHz TE 22,6 gyrotron are presented and compared with theory. The theoretical excitation regimes of competing modes are computed in the energy-velocity-pitch-angle plane near the operation point. The startup paths through the plane are determined by the time evolution of the beam parameters during the startup phase. These startup paths are modified by changing the anode and cathode voltage rise from zero to their nominal values and are seen to determine the cavity oscillating mode. Experimental results show specifically that competition between the TE 22,6 and TE -19,7 mode can be completely eliminated by using the proper startup method in a case where a typical triode startup results in oscillation in the competing TE -19,7 mode. These new results are shown to be in excellent agreement with theory whose approach is general and therefore applicable to gyrotrons operating in any arbitrary cavity mode. (author) 5 figs., 1 tab., 13 refs

  6. Atomic nuclei decay modes by spontaneous emission of heavy ions

    International Nuclear Information System (INIS)

    Poenaru, D.N.; Ivascu, M.; Sandulescu, A.

    1984-01-01

    The great majority of the known nuclei, including the so-called stable nuclides, are in fact metastable with respect to several modes of spontaneous superasymmetric splitting. If the lifetime against these processes is larger than 10 30 s, the phenomenon is not detectable with available experimental techniques, hence one can admit stability from the practical point of view. A model extended from the fission theory of alpha decay allows one to estimate the lifetimes and the branching ratios relatively to the alpha decay for these natural radioactivities. From a huge amount of systematical calculations it is concluded that the process should proceed with maximum intensity in the trans-lead nuclei, where the minimum lifetime is obtained for parent nuclei - heavy clusters leading to a magic ( 208 Pb) or almost daughter nucleus. More than 140 nuclides with atomic number smaller than 25 are possible candidates to be emitted from heavy nuclei, with half-life n the 10 10 -10 30 s range. The shell structure and pairing effects are clearly manifested in these new decay modes

  7. Over 19 W Single-Mode 1545 nm Er,Yb Codoped All-Fiber Laser

    Directory of Open Access Journals (Sweden)

    Jiadong Wu

    2017-01-01

    Full Text Available We report a high-power cladding-pumped Er,Yb codoped all-fiber laser with truly single transverse mode output. The fiber laser is designed to operate at 1545 nm by the use of a pair of fiber Bragg gratings (FBGs to lock and narrow the output spectrum, which can be very useful in generating the eye-safe ~1650 nm laser emission through the Stimulated Raman Scattering (SRS in silica fibers that is of interest in many applications. Two pieces of standard single-mode fibers are inserted into the laser cavity and output port to guarantee the truly single-mode output as well as good compatibility with other standard fiber components. We have obtained a maximum output power of 19.2 W at 1544.68 nm with a FWHM spectral width of 0.08 nm, corresponding to an average overall slope efficiency of 31.9% with respect to the launched pump power. This is, to the best of our knowledge, the highest output power reported from simple all-fiber single-mode Er,Yb codoped laser oscillator architecture.

  8. 40 CFR 1033.515 - Discrete-mode steady-state emission tests of locomotives and locomotive engines.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Discrete-mode steady-state emission... Procedures § 1033.515 Discrete-mode steady-state emission tests of locomotives and locomotive engines. This... a warm-up followed by a sequence of nominally steady-state discrete test modes, as described in...

  9. Single-mode glass waveguide technology for optical interchip communication on board level

    Science.gov (United States)

    Brusberg, Lars; Neitz, Marcel; Schröder, Henning

    2012-01-01

    The large bandwidth demand in long-distance telecom networks lead to single-mode fiber interconnects as result of low dispersion, low loss and dense wavelength multiplexing possibilities. In contrast, multi-mode interconnects are suitable for much shorter lengths up to 300 meters and are promising for optical links between racks and on board level. Active optical cables based on multi-mode fiber links are at the market and research in multi-mode waveguide integration on board level is still going on. Compared to multi-mode, a single-mode waveguide has much more integration potential because of core diameters of around 20% of a multi-mode waveguide by a much larger bandwidth. But light coupling in single-mode waveguides is much more challenging because of lower coupling tolerances. Together with the silicon photonics technology, a single-mode waveguide technology on board-level will be the straight forward development goal for chip-to-chip optical interconnects integration. Such a hybrid packaging platform providing 3D optical single-mode links bridges the gap between novel photonic integrated circuits and the glass fiber based long-distance telecom networks. Following we introduce our 3D photonic packaging approach based on thin glass substrates with planar integrated optical single-mode waveguides for fiber-to-chip and chip-to-chip interconnects. This novel packaging approach merges micro-system packaging and glass integrated optics. It consists of a thin glass substrate with planar integrated singlemode waveguide circuits, optical mirrors and lenses providing an integration platform for photonic IC assembly and optical fiber interconnect. Thin glass is commercially available in panel and wafer formats and characterizes excellent optical and high-frequency properties. That makes it perfect for microsystem packaging. The paper presents recent results in single-mode waveguide technology on wafer level and waveguide characterization. Furthermore the integration in a

  10. Quantification in single photon emission computed tomography (SPECT)

    International Nuclear Information System (INIS)

    Buvat, Irene

    2005-01-01

    The objective of this lecture is to understand the possibilities and limitations of the quantitative analysis of single photon emission computed tomography (SPECT) images. It is also to identify the conditions to be fulfilled to obtain reliable quantitative measurements from images. Content: 1 - Introduction: Quantification in emission tomography - definition and challenges; quantification biasing phenomena; 2 - quantification in SPECT, problems and correction methods: Attenuation, scattering, un-stationary spatial resolution, partial volume effect, movement, tomographic reconstruction, calibration; 3 - Synthesis: actual quantification accuracy; 4 - Beyond the activity concentration measurement

  11. Edge field emission of large-area single layer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Kleshch, Victor I., E-mail: klesch@polly.phys.msu.ru [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Bandurin, Denis A. [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Orekhov, Anton S. [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); A.V. Shubnikov Institute of Crystallography, RAS, Moscow 119333 (Russian Federation); Purcell, Stephen T. [ILM, Université Claude Bernard Lyon 1 et CNRS, UMR 5586, 69622 Villeurbanne (France); Obraztsov, Alexander N. [Department of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Department of Physics and Mathematics, University of Eastern Finland, Joensuu 80101 (Finland)

    2015-12-01

    Graphical abstract: - Highlights: • Stable field emission was observed from the edge of large-area graphene on quartz. • A strong hysteresis in current–voltage characteristics was observed. • The hysteresis was explained by mechanical peeling of graphene edge from substrate. • Reversible peeling of graphene edge may be used in microelectromechanical systems. - Abstract: Field electron emission from the edges of large-area (∼1 cm × 1 cm) graphene films deposited onto quartz wafers was studied. The graphene was previously grown by chemical vapour deposition on copper. An extreme enhancement of electrostatic field at the edge of the films with macroscopically large lateral dimensions and with single atom thickness was achieved. This resulted in the creation of a blade type electron emitter, providing stable field emission at low-voltage with linear current density up to 0.5 mA/cm. A strong hysteresis in current–voltage characteristics and a step-like increase of the emission current during voltage ramp up were observed. These effects were explained by the local mechanical peeling of the graphene edge from the quartz substrate by the ponderomotive force during the field emission process. Specific field emission phenomena exhibited in the experimental study are explained by a unique combination of structural, electronic and mechanical properties of graphene. Various potential applications ranging from linear electron beam sources to microelectromechanical systems are discussed.

  12. Impacts of Urban Transportation Mode Split on CO2 Emissions in Jinan, China

    Directory of Open Access Journals (Sweden)

    Kebin He

    2011-04-01

    Full Text Available As the world’s largest developing country, China currently is undergoing rapid urbanization and motorization, which will result in far-reaching impacts on energy and the environment. According to estimates, energy use and carbon emissions in the transportation sector will comprise roughly 30% of total emissions by 2030. Since the late 1990s, transportation-related issues such as energy, consumption, and carbon emissions have become a policy focus in China. To date, most research and policies have centered on vehicle technologies that promote vehicle efficiency and reduced emissions. Limited research exists on the control of greenhouse gases through mode shifts in urban transportation—in particular, through the promotion of public transit. The purpose of this study is to establish a methodology to analyze carbon emissions from the urban transportation sector at the Chinese city level. By using Jinan, the capital of China’s Shandong Province, as an example, we have developed an analytical model to simulate energy consumption and carbon emissions based on the number of trips, the transportation mode split, and the trip distance. This model has enabled us to assess the impacts of the transportation mode split on energy consumption and carbon emissions. Furthermore, this paper reviews a set of methods for data collection, estimation, and processing for situations where statistical data are scarce in China. This paper also describes the simulation of three transportation system development scenarios. The results of this study illustrate that if no policy intervention is implemented for the transportation mode split (the business-as-usual (BAU case, then emissions from Chinese urban transportation systems will quadruple by 2030. However, a dense, mixed land-use pattern, as well as transportation policies that encourage public transportation, would result in the elimination of 1.93 million tons of carbon emissions—approximately 50% of the BAU

  13. Single-transverse-mode Ti:sapphire rib waveguide laser

    NARCIS (Netherlands)

    Grivas, C.; Shepherd, D.P.; May-Smith, T.C.; Eason, R.W.; Pollnau, Markus

    2005-01-01

    Laser operation of Ti:sapphire rib waveguides fabricated using photolithography and ion beam etching in pulsed laser deposited layers is reported. Polarized laser emission was observed at 792.5 nm with an absorbed pump power threshold of 265 mW, which is more than a factor of 2 lower in comparison

  14. Interaction of solitary pulses in single mode optical fibres | Usman ...

    African Journals Online (AJOL)

    Two solitary waves launched, by way of incidence, into an optical fibre from a single pulse if the pulses are in-phase as understood from results of inverse scattering transform method applied to the cubic nonlinear Schrödinger equations, (CNLSE\\'s). The single CNLSE is then understood to describe evolution of coupled ...

  15. Refractive index sensor based on an abrupt taper Michelson interferometer in a single-mode fiber.

    Science.gov (United States)

    Tian, Zhaobing; Yam, Scott S-H; Loock, Hans-Peter

    2008-05-15

    A simple refractive index sensor based on a Michelson interferometer in a single-mode fiber is constructed and demonstrated. The sensor consists of a single symmetrically abrupt taper region in a short piece of single-mode fiber that is terminated by approximately 500 nm thick gold coating. The sensitivity of the new sensor is similar to that of a long-period-grating-type sensor, and its ease of fabrication offers a low-cost alternative to current sensing applications.

  16. Comparison of single-/few-/multi-mode 850 nm VCSELs for optical OFDM transmission.

    Science.gov (United States)

    Kao, Hsuan-Yun; Tsai, Cheng-Ting; Leong, Shan-Fong; Peng, Chun-Yen; Chi, Yu-Chieh; Huang, Jian Jang; Kuo, Hao-Chung; Shih, Tien-Tsorng; Jou, Jau-Ji; Cheng, Wood-Hi; Wu, Chao-Hsin; Lin, Gong-Ru

    2017-07-10

    For high-speed optical OFDM transmission applications, a comprehensive comparison of the homemade multi-/few-/single-transverse mode (MM/FM/SM) vertical cavity surface emitting laser (VCSEL) chips is performed. With microwave probe, the direct encoding of pre-leveled 16-QAM OFDM data and transmission over 100-m-long OM4 multi-mode-fiber (MMF) are demonstrated for intra-datacenter applications. The MM VCSEL chip with the largest emission aperture of 11 μm reveals the highest differential quantum efficiency which provides the highest optical power of 8.67 mW but exhibits the lowest encodable bandwidth of 21 GHz. In contrast, the SM VCSEL chip fabricated with the smallest emission aperture of only 3 μm provides the highest 3-dB encoding bandwidth up to 23 GHz at a cost of slight heat accumulation. After optimization, with the trade-off set between the receiving signal-to-noise ratio (SNR) and bandwidth, the FM VCSEL chip guarantees the highest optical OFDM transmission bit rate of 96 Gbit/s under back-to-back case with its strongest throughput. Among three VCSEL chips, the SM VCSEL chip with nearly modal-dispersion free feature is treated as the best candidate for carrying the pre-leveled 16-QAM OFDM data over 100-m OM4-MMF with same material structure but exhibits different oxide-layer confined gain cross-sections with one another at 80-Gbit/s with the smallest receiving power penalty of 1.77 dB.

  17. Electronically Tunable Current-Mode Quadrature Oscillator Using Single MCDTA

    Directory of Open Access Journals (Sweden)

    Y. Li

    2010-12-01

    Full Text Available This paper presents a modified current differencing transconductance amlpifier (MCDTA and the MCDTA based quadrature oscillator. The oscillator is current-mode and provides current output from high output impedance terminals. The circuit uses only one MCDTA and two grounded capacitors, and is easy to be integrated. Its oscillation frequency can be tuned electronically by tuning bias currents of MCDTA. Finally, frequency error is analyzed. The results of circuit simulations are in agreement with theory.

  18. Time-optimal thermalization of single-mode Gaussian states

    Science.gov (United States)

    Carlini, Alberto; Mari, Andrea; Giovannetti, Vittorio

    2014-11-01

    We consider the problem of time-optimal control of a continuous bosonic quantum system subject to the action of a Markovian dissipation. In particular, we consider the case of a one-mode Gaussian quantum system prepared in an arbitrary initial state and which relaxes to the steady state due to the action of the dissipative channel. We assume that the unitary part of the dynamics is represented by Gaussian operations which preserve the Gaussian nature of the quantum state, i.e., arbitrary phase rotations, bounded squeezing, and unlimited displacements. In the ideal ansatz of unconstrained quantum control (i.e., when the unitary phase rotations, squeezing, and displacement of the mode can be performed instantaneously), we study how control can be optimized for speeding up the relaxation towards the fixed point of the dynamics and we analytically derive the optimal relaxation time. Our model has potential and interesting applications to the control of modes of electromagnetic radiation and of trapped levitated nanospheres.

  19. Tunable single and dual mode operation of an external cavity quantum-dot injection laser

    International Nuclear Information System (INIS)

    Biebersdorf, A; Lingk, C; De Giorgi, M; Feldmann, J; Sacher, J; Arzberger, M; Ulbrich, C; Boehm, G; Amann, M-C; Abstreiter, G

    2003-01-01

    We investigate quantum-dot (QD) lasers in an external cavity using Littrow and Littman configurations. Here, we report on a continuously tunable QD laser with a broad tuning range from 1047 to 1130 nm with high stability and efficient side mode suppression. The full-width at half-maximum of the laser line is 0.85 nm determined mainly by the quality of the external grating. This laser can be operated in a dual-mode modus, where the mode-spacing can be tuned continuously between 1.1 and 34 nm. Simultaneous emission of the two laser modes is shown by sum frequency generation experiments

  20. Photon emission by electrons and positrons traversing thin single crystal

    International Nuclear Information System (INIS)

    Ol'chak, A.S.

    1984-01-01

    Radiation emission by planar channeled particles (electrons, positrons) in a thin single crystal of thickness L is considered. It is shown that for L approximately πb/THETAsub(L) (b is the lattice constant, THETA sub(L) the Lindhard angle) besides the main spontaneous channeling maxima there exist auxiliary interference maxima, the positions of all the maxima depending on L. The dependence of the radiation spectral intensity on crystal thickness is discussed

  1. Manipulating single second mode transparency in a corrugated waveguide via the thickness of sputtered gold

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Dan [Key Lab of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); Photonics Research Center, College of Science, Harbin Engineering University, Harbin 150001 (China); Fan, Ya-Xian, E-mail: yxfan@hrbeu.edu.cn [Key Lab of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); Photonics Research Center, College of Science, Harbin Engineering University, Harbin 150001 (China); Sang, Tang-Qing; Xu, Lan-Lan; Bibi, Aysha [Key Lab of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); Photonics Research Center, College of Science, Harbin Engineering University, Harbin 150001 (China); Tao, Zhi-Yong, E-mail: zytao@hrbeu.edu.cn [Key Lab of In-fiber Integrated Optics, Ministry of Education of China, Harbin Engineering University, Harbin 150001 (China); Photonics Research Center, College of Science, Harbin Engineering University, Harbin 150001 (China)

    2016-03-11

    We propose a classical analog of electromagnetically induced transparency in a cylindrical waveguide with undulated metallic walls. The transparency, induced by multi-mode interactions in waveguides, not only has a narrow line-width, but also consists of a single second-order transverse mode, which corresponds to the Bessel function distributions investigated extensively due to their unique characteristics. By increasing the thickness of sputtered gold layers of the waveguide, we demonstrate a frequency-agile single mode transparency phenomenon in a terahertz radiation. It is found that the center frequency of the transparency is linearly related to the gold thickness, indicating the achievement of a controllable single mode terahertz device. The field distributions at the cross-sections of outlets verify the single second mode transparency and indicate the mechanism of its frequency manipulation, which will significantly benefit the mode-control engineering in terahertz applications. - Highlights: • An analog of electromagnetically induced transparency in terahertz tubes is proposed. • A single second transverse mode of Bessel distributions is observed in the pass band. • The operating frequency can be linearly controlled by the sputtered gold thickness. • We can effectively manipulate the slow down factor of light by the gold thickness. • The transparency characteristics rely on the transition of multi-mode interactions.

  2. Manipulating single second mode transparency in a corrugated waveguide via the thickness of sputtered gold

    International Nuclear Information System (INIS)

    Xu, Dan; Fan, Ya-Xian; Sang, Tang-Qing; Xu, Lan-Lan; Bibi, Aysha; Tao, Zhi-Yong

    2016-01-01

    We propose a classical analog of electromagnetically induced transparency in a cylindrical waveguide with undulated metallic walls. The transparency, induced by multi-mode interactions in waveguides, not only has a narrow line-width, but also consists of a single second-order transverse mode, which corresponds to the Bessel function distributions investigated extensively due to their unique characteristics. By increasing the thickness of sputtered gold layers of the waveguide, we demonstrate a frequency-agile single mode transparency phenomenon in a terahertz radiation. It is found that the center frequency of the transparency is linearly related to the gold thickness, indicating the achievement of a controllable single mode terahertz device. The field distributions at the cross-sections of outlets verify the single second mode transparency and indicate the mechanism of its frequency manipulation, which will significantly benefit the mode-control engineering in terahertz applications. - Highlights: • An analog of electromagnetically induced transparency in terahertz tubes is proposed. • A single second transverse mode of Bessel distributions is observed in the pass band. • The operating frequency can be linearly controlled by the sputtered gold thickness. • We can effectively manipulate the slow down factor of light by the gold thickness. • The transparency characteristics rely on the transition of multi-mode interactions.

  3. An optical technique to measure the frequency and mode emission of tunable lasers

    International Nuclear Information System (INIS)

    Marchetti, S.; Simili, R.

    1988-01-01

    To use mode tunable lasers it is necessary to measure the laser frequency and the mode emission. This problem is very important when waveguide lasers are used. Normally this information is obtained by a heterodyne technique, but there are some difficulties to perform this method in a large electrical noise environment, when pulsed of radiofrequency lasers are used. This laser information was obtained by using an alternative low-cost optical system. With this apparatus the cavity pulling was measured and an upper limit for the linewidth of a radiofrequency, high pressure, line and mode-tunable, CO 2 laser was roughly estimated

  4. single photon emission tomography and positron emission tomography - Part 1 (October 2012), Part 2 (October 2010)

    International Nuclear Information System (INIS)

    Buvat, Irene

    2010-10-01

    The objective of this lecture is to present the single photon emission computed tomography (SPECT) and the positron emission tomography (PET) imaging techniques. Part 1 Content: 1 - Introduction: anatomic, functional and molecular imaging; 2 - Radiotracers: chemical and physical constraints, gamma photon emitters, positon emitters, radioisotopes production, emitters type and imaging techniques; 3 - Gamma cameras; 4 - Quantification in emission tomography: attenuation, scattering, un-stationary spatial resolution; 5 - Synthesis and conclusion. Part 2 content: 1 - Positon emitters; 2 - Positons detection: Coincidence detection (electronic collimation, PET detectors with gamma cameras, dedicated PET detectors, spectrometry); PET detectors type; time-of-flight PET; 2D PET; 3D PET; 3 - Quantification in emission tomography: detected events, attenuation, scattering, fortuitous coincidences, standardisation; 4 - Common SPECT and PET problems: partial volume effect, movement, tomographic reconstruction, calibration, dead time; 5 - Synthesis and conclusion

  5. Quantum dash based single section mode locked lasers for photonic integrated circuits.

    Science.gov (United States)

    Joshi, Siddharth; Calò, Cosimo; Chimot, Nicolas; Radziunas, Mindaugas; Arkhipov, Rostislav; Barbet, Sophie; Accard, Alain; Ramdane, Abderrahim; Lelarge, Francois

    2014-05-05

    We present the first demonstration of an InAs/InP Quantum Dash based single-section frequency comb generator designed for use in photonic integrated circuits (PICs). The laser cavity is closed using a specifically designed Bragg reflector without compromising the mode-locking performance of the self pulsating laser. This enables the integration of single-section mode-locked laser in photonic integrated circuits as on-chip frequency comb generators. We also investigate the relations between cavity modes in such a device and demonstrate how the dispersion of the complex mode frequencies induced by the Bragg grating implies a violation of the equi-distance between the adjacent mode frequencies and, therefore, forbids the locking of the modes in a classical Bragg Device. Finally we integrate such a Bragg Mirror based laser with Semiconductor Optical Amplifier (SOA) to demonstrate the monolithic integration of QDash based low phase noise sources in PICs.

  6. Decay properties of high-lying single-particles modes

    NARCIS (Netherlands)

    Beaumel, D; Fortier, S; Gales, S; Guillot, J; LangevinJoliot, H; Laurent, H; Maison, JM; Vernotte, J; Bordewijck, J; Brandenburg, S; Krasznahorkay, A; Crawley, GM; Massolo, CP; Renteria, M; Khendriche, A

    1996-01-01

    The neutron decay of high-lying single-particle states in Ni-64, Zr-90, Sn-120 and (208)pb excited by means of the (alpha,He-3) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular

  7. Attenuation Coefficient of Single-Mode Periodic Waveguides

    Science.gov (United States)

    Baron, A.; Mazoyer, S.; Smigaj, W.; Lalanne, P.

    2011-10-01

    It is widely accepted that, on ensemble average, the transmission T of guided modes decays exponentially with the waveguide length L due to small imperfections, leading to the important figure of merit defined as the attenuation-rate coefficient α=-⟨ln⁡(T)⟩/L. In this Letter, we evidence that the exponential-damping law is not valid in general for periodic monomode waveguides, especially as the group velocity decreases. This result, that contradicts common beliefs and experimental practices aiming at measuring α, is supported by a theoretical study of light transport in the limit of very small imperfections, and by numerical results obtained for two waveguide geometries that offer contrasted damping behaviors.

  8. Light emission from organic single crystals operated by electrolyte doping

    Science.gov (United States)

    Matsuki, Keiichiro; Sakanoue, Tomo; Yomogida, Yohei; Hotta, Shu; Takenobu, Taishi

    2018-03-01

    Light-emitting devices based on electrolytes, such as light-emitting electrochemical cells (LECs) and electric double-layer transistors (EDLTs), are solution-processable devices with a very simple structure. Therefore, it is necessary to apply this device structure into highly fluorescent organic materials for future printed applications. However, owing to compatibility problems between electrolytes and organic crystals, electrolyte-based single-crystal light-emitting devices have not yet been demonstrated. Here, we report on light-emitting devices based on organic single crystals and electrolytes. As the fluorescent materials, α,ω-bis(biphenylyl)terthiophene (BP3T) and 5,6,11,12-tetraphenylnaphthacene (rubrene) single crystals were selected. Using ionic liquids as electrolytes, we observed clear light emission from BP3T LECs and rubrene EDLTs.

  9. B-mode contamination by synchrotron emission from 3-yr Wilkinson Microwave Anisotropy Probe data

    NARCIS (Netherlands)

    Carretti, E.; Bernardi, G.; Cortiglioni, S.

    2006-01-01

    We study the contamination of the B-mode of the cosmic microwave background polarization (CMBP) by Galactic synchrotron in the lowest emission regions of the sky. The 22.8-GHz polarization map of the 3-yr Wilkinson Microwave Anisotropy Probe (WMAP) data release is used to identify and analyse such

  10. Low-loss single-mode hollow-core fiber with anisotropic anti-resonant elements

    DEFF Research Database (Denmark)

    Habib, Selim; Bang, Ole; Bache, Morten

    2016-01-01

    A hollow-core fiber using anisotropic anti-resonant tubes in thecladding is proposed for low loss and effectively single-mode guidance. We show that the loss performance and higher-order mode suppression is significantly improved by using symmetrically distributed anisotropic antiresonant tubes i...

  11. Mode of transport to work, car ownership and CO{sub 2} emissions in Mauritius

    Energy Technology Data Exchange (ETDEWEB)

    Jaunky, V.C. (ETH Zuerich. Centre for Energy Policy and Economics, Zuerich (Switzerland)); Bundhoo, M.N.; Moco, S.Y. (Mauritius (Mauritius))

    2011-05-15

    Fast economical and demographic revolution in the small island developing state of Mauritius over the last decades has led to an unprecedented rise in private vehicle utilization. In this arena, the cognition of ongoing travel practices and their determinants is sine qua non. This paper examines the determinants of mode of transport, rise in car ownership and its related environmental impacts. We employ cross-section micro-data obtained from our household drop-off survey to estimate a multinomial logistic regression model of transport mode choice coupled with an exhaustive ordinary least squares analysis of carbon emissions. Empirical results indicate that factors such as travel time, expenses and time lost in traffic jam coupled with demographic and socio-economic characteristics such as age of individual and household income have profound upshots on transport mode decisions. On the other hand, fuel type, residential distance from work and age of individual displays statistically significant impacts on carbon dioxide emissions. (Author)

  12. Amplitude Noise Suppression and Orthogonal Multiplexing Using Injection-Locked Single-Mode VCSEL

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir; von Lerber, Tuomo; Lassas, Matti

    2017-01-01

    We experimentally demonstrate BER reduction and orthogonal modulation using an injection locked single-mode VCSEL. It allows us suppressing an amplitude noise of optical signal and/or double the capacity of an information channel.......We experimentally demonstrate BER reduction and orthogonal modulation using an injection locked single-mode VCSEL. It allows us suppressing an amplitude noise of optical signal and/or double the capacity of an information channel....

  13. Celiac disease biodetection using lossy-mode resonances generated in tapered single-mode optical fibers

    Science.gov (United States)

    Socorro, A. B.; Corres, J. M.; Del Villar, I.; Matias, I. R.; Arregui, F. J.

    2014-05-01

    This work presents the development and test of an anti-gliadin antibodies biosensor based on lossy mode resonances (LMRs) to detect celiac disease. Several polyelectrolites were used to perform layer-by-layer assembly processes in order to generate the LMR and to fabricate a gliadin-embedded thin-film. The LMR shifted 20 nm when immersed in a 5 ppm anti-gliadin antibodies-PBS solution, what makes this bioprobe suitable for detecting celiac disease. This is the first time, to our knowledge, that LMRs are used to detect celiac disease and these results suppose promising prospects on the use of such phenomena as biological detectors.

  14. Single photon emission computed tomography and oth selected computer topics

    International Nuclear Information System (INIS)

    Frey, G.D.

    1981-01-01

    This book, the proceedings of a meeting in January 1980, contains 21 papers. Thirteen are devoted to aspects of emission tomography, four to nuclear cardiology, and five to other topics. The initial set of papers consists of reviews of the single photon emission tomography process. These include transverse axial tomography using scintillation cameras and other devices, longitudinal section tomography, and pin-hole and slant-hole systems. These reviews are generally well done, but as might be expected, lack any coherence from paper to paper. The papers on nuclear cardiology include several of Fourier analysis in nuclear cardiology and one on shunt quantification. Other clinical papers are on quantifying Tc-99m glucoheptonate uptake in the brain and on iron-59 retention studies. A general criticism of the book is the poor quality of photographic reproductions

  15. Decay properties of high-lying single-particles modes

    Science.gov (United States)

    Beaumel, D.; Fortier, S.; Galès, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J. M.; Vernotte, J.; Bordewijck, J.; Brandenburg, S.; Krasznahorkay, A.; Crawley, G. M.; Massolo, C. P.; Renteria, M.; Khendriche, A.

    1996-02-01

    The neutron decay of high-lying single-particle states in 64Ni, 90Zr, 120Sn and 208Pb excited by means of the (α, 3He) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular correlation analysis. The structure located between 11 and 15 MeV in 91Zr, and between 8 and 12 MeV excitation energy in 209Pb display large departures from a pure statistical decay. The corresponding non-statistical branching ratios are compared with the results of two theoretical calculations.

  16. Characteristics of dioxin emissions from a Waelz plant with acid and basic kiln mode.

    Science.gov (United States)

    Hung, Pao Chen; Chi, Kai Hsien; Chen, Mei Lien; Chang, Moo Been

    2012-01-30

    The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were measured in the flue gas of a Waelz plant operated in acid and basic modes, respectively. To abate (PCDD/F) and other pollutants, the plant operates with a post-treatment of flue gases by activated carbon injection and subsequent filtration. Relatively high PCDD/F discharge by fly ashes is found with acid kiln mode of the Waelz process. Therefore, basic kiln mode of the Waelz process is investigated and compared in this plant. With the adsorbent injection rate of 7 kg/h (95 mg/Nm(3)), the PCDD/F concentration in stack gas was measured as 0.123 ng I-TEQ/Nm(3) in the basic operating mode. The added Ca(OH)(2) reacted with metal catalysts and HCl((g)) in the flue gas and thus effectively suppressed the formation of PCDD/Fs. PCDD/F concentrations in fly ashes sampled from the dust settling chamber, cyclone, primary filter and secondary filter in basic kiln mode were significantly lower than that in acid kiln mode. Total PCDD/F emission on the basis of treating one kg of electric arc furnace dust in the basic operation mode was 269 ng I-TEQ/kg EAF-dust treated which was significantly lower than that in acid mode (640 ng I-TEQ/kg EAF-dust treated). Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Single mode operation of a hybrid optically pumped D2O far infrared laser

    International Nuclear Information System (INIS)

    Yuan, D.C.; Siegrist, M.R.

    1990-04-01

    We have achieved single mode operation in a hybrid optically pumped D 2 O far infrared laser. The active volume of the resonator was divided into two sections separated by a thin plastic foil. The larger section served as the main gain medium and the shorter section as mode selective element. The vapor pressure in the smaller volume was either very low or alternatively about 3 times higher than the pressure in the main part. In both cases single mode operation was achieved without any reduction of the total output energy. (author) 13 refs., 7 figs

  18. Decay properties of high-lying single-particles modes

    Energy Technology Data Exchange (ETDEWEB)

    Beaumel, D. [Institut de Physique Nucleaire, 91 - Orsay (France); Fortier, S. [Institut de Physique Nucleaire, 91 - Orsay (France); Gales, S. [Institut de Physique Nucleaire, 91 - Orsay (France); Guillot, J. [Institut de Physique Nucleaire, 91 - Orsay (France); Langevin-Joliot, H. [Institut de Physique Nucleaire, 91 - Orsay (France); Laurent, H. [Institut de Physique Nucleaire, 91 -Orsay (France); Maison, J.M. [Institut de Physique Nucleaire, 91 - Orsay (France); Vernotte, J. [Institut de Physique Nucleaire, 91 - Orsay (France); Bordewijck, J. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Brandenburg, S. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Krasznahorkay, A. [Kernfysisch Versneller Instituut, 9747 Groningen (Netherlands); Crawley, G.M. [NSCL, Michigan State University, East Lansing, MI 48824 (United States); Massolo, C.P. [Universitad Nacional de La Plata, 1900 La Plata (Argentina); Renteria, M. [Universitad Nacional de La Plata, 1900 La Plata (Argentina); Khendriche, A. [University of Tizi-Ouzou, Tizi-Ouzou (Algeria)

    1996-03-18

    The neutron decay of high-lying single-particle states in {sup 64}Ni, {sup 90}Zr, {sup 120}Sn and {sup 208}Pb excited by means of the ({alpha},{sup 3}He) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular correlation analysis. The structure located between 11 and 15 MeV in {sup 91}Zr, and between 8 and 12 MeV excitation energy in {sup 209}Pb display large departures from a pure statistical decay. The corresponding non-statistical branching ratios are compared with the results of two theoretical calculations. (orig.).

  19. Single photon emission computed tomography in children with idiopathic seizures

    International Nuclear Information System (INIS)

    Hara, Masafumi; Takahashi, Mutsumasa; Kojima, Akihiro; Shimomura, Osamu; Kinoshita, Rumi; Tomiguchi, Seiji; Taku, Keiichi; Miike, Teruhisa

    1991-01-01

    Single photon emission computed tomography (SPECT) with N-isoprophyl-p [ 123 I]-iodoamphetamine (IMP), X-ray computed tomography (X-CT), and magnetic resonance imaging (MRI) were performed in 20 children with idiopathic seizures. In children with idiopathic seizures, SPECT could detect the abnormal sites at the highest rate (45%) compared with CT (10%) and MRI (12%), but the abnormal sites on SPECT correlated poorly with the foci on electroencephalograph (EEG). Idiopathic epilepsy with hypoperfusion on SPECT was refractory to treatment and was frequently associated with mental and/or developmental retardation. Perfusion defects on SPECT scans probably affect the development and maturation of the brain in children. (author)

  20. Effect of injection pressure on performance, emission, and combustion characteristics of diesel-acetylene-fuelled single cylinder stationary CI engine.

    Science.gov (United States)

    Srivastava, Anmesh Kumar; Soni, Shyam Lal; Sharma, Dilip; Jain, Narayan Lal

    2018-03-01

    In this paper, the effect of injection pressure on the performance, emission, and combustion characteristics of a diesel-acetylene fuelled single cylinder, four-stroke, direct injection (DI) diesel engine with a rated power of 3.5 kW at a rated speed of 1500 rpm was studied. Experiments were performed in dual-fuel mode at four different injection pressures of 180, 190, 200, and 210 bar with a flow rate of 120 LPH of acetylene and results were compared with that of baseline diesel operation. Experimental results showed that highest brake thermal efficiency of 27.57% was achieved at injection pressure of 200 bar for diesel-acetylene dual-fuel mode which was much higher than 23.32% obtained for baseline diesel. Carbon monoxide, hydrocarbon, and smoke emissions were also measured and found to be lower, while the NO x emissions were higher at 200 bar in dual fuel mode as compared to those in other injection pressures in dual fuel mode and also for baseline diesel mode. Peak cylinder pressure, net heat release rate, and rate of pressure rise were also calculated and were higher at 200 bar injection pressure in dual fuel mode.

  1. X-mode artificial optical emissions and attendant phenomena at EISCAT/Heating

    Science.gov (United States)

    Blagoveshchenskaya, Nataly; Sergienko, Tima; Rietveld, Michael; Brandstrom, Urban; Senior, Andrew; Haggstrom, Ingemar; Kosch, Michael; Borisova, Tatiana; Yeoman, Tim

    We present the experimental evidence for the formation of the artificial optical emissions induced by the X-mode powerful HF radio waves injected towards the magnetic zenith (MZ) into the high latitude F region of the ionosphere. The experiments were conducted in the course of Russian EISCAT heating campaigns in October 2012 and October 2013 at the Heating facility at Tromsø, Norway. The HF pump wave with the X-mode polarization was radiated at 7.1 or 6.2 MHz. The phased array 1, resulting in an ERP = 430 - 600 MW was used. Optical emissions at red (630 nm) and green (557 nm) lines were imaged from Tromsø site by the digital All-Sky Imager mark 2 (DASI - 2) and from a remote site at Abisco by the Auroral Large Imaging System (ALIS) in Scandinavia. The intensities of X-mode emissions at red and green lines varied between about of 150 - 1000 R and 50 - 300 R above the background respectively in different experiments. The artificial optical emissions were accompanied by very strong HF-enhanced ion lines and HF induced plasma lines from the EISCAT UHF incoherent scatter radar measurements and artificial small-scale field-aligned irregularities from CUTLASS (SuperDARN) HF coherent radar in Finland. The results obtained are discussed.

  2. Emissions from large-scale medium-speed diesel engines: 2. Influence of fuel type and operating mode

    International Nuclear Information System (INIS)

    Sarvi, Arto; Zevenhoven, Ron; Fogelholm, Carl-Johan

    2008-01-01

    This paper addresses gaseous emissions smoke (soot) and particulate matter in large-scale diesel engine exhaust. The test engine was a large-scale turbocharged, after-cooled mean speed (∝ 500 rpm) direct-injection diesel engine and the power per cylinder was about 1 MW. Emission measurements were carried out on burning heavy fuel (HFO) and light fuel (LFO) oils. The test modes for the investigation were a propulsion mode (marine application) and a generator mode (power plant application). Gaseous emissions were measured according to the IMO technical code, smoke (soot) emissions were determined optically and particulate matter (PM) was measured by gravimetric impactor designed for five size fractions. In comparison the emissions from HFO and LFO utilisations indicate slightly higher NO and CO emissions for HFO, while LFO gives clearly higher emissions of hydrocarbons (HC). Emissions of soot and CO appeared to correlate very well, being very high for both fuels throughout the propulsion mode and low load, otherwise being similar for both modes. PM emissions are more than three times higher with HFO than with LFO and appear to decrease with the load except for HFO during the generator mode where an increase of PM emissions with the load is seen. Some data on sampled particles is given. (author)

  3. The Influence of Various Operation Modes on Diesel Passenger Cars CO2 Emissions

    Directory of Open Access Journals (Sweden)

    Arina Negoițescu

    2015-07-01

    Full Text Available The amount of emissions released into the atmosphere by polluting sources was significantly reduced due to the limitations introduced by the EU. Since one of the main sources affecting air quality is the car, researches regarding the influence of various factors on exhaust emissions are carried out. As CO2 is the main pollutant responsible for the greenhouse effect, the article treats the influence of vehicle load and traffic levels, running modes, the electric consumer’s utilization, and driving style on CO2 emissions for cars equipped with diesel engine. The results from the conducted study can contribute to adopt solutions in order to decrease the concentration of CO2 emissions from cars equipped with diesel engines.

  4. Multi-level single mode 2D polymer waveguide optical interconnects using nano-imprint lithography

    NARCIS (Netherlands)

    Khan, M.U.; Justice, J.; Petäjä, J.; Korhonen, T.; Boersma, A.; Wiegersma, S.; Karppinen, M.; Corbett, B.

    2015-01-01

    Single and multi-layer passive optical interconnects using single mode polymer waveguides are demonstrated using UV nano-imprint lithography. The fabrication tolerances associated with imprint lithography are investigated and we show a way to experimentally quantify a small variation in index

  5. A New Three-Dimensional High-Accuracy Automatic Alignment System For Single-Mode Fibers

    Science.gov (United States)

    Yun-jiang, Rao; Shang-lian, Huang; Ping, Li; Yu-mei, Wen; Jun, Tang

    1990-02-01

    In order to achieve the low-loss splices of single-mode fibers, a new three-dimension high-accuracy automatic alignment system for single -mode fibers has been developed, which includes a new-type three-dimension high-resolution microdisplacement servo stage driven by piezoelectric elements, a new high-accuracy measurement system for the misalignment error of the fiber core-axis, and a special single chip microcomputer processing system. The experimental results show that alignment accuracy of ±0.1 pin with a movable stroke of -±20μm has been obtained. This new system has more advantages than that reported.

  6. Feasibility of efficient room-temperature solid-state sources of indistinguishable single photons using ultrasmall mode volume cavities

    Science.gov (United States)

    Wein, Stephen; Lauk, Nikolai; Ghobadi, Roohollah; Simon, Christoph

    2018-05-01

    Highly efficient sources of indistinguishable single photons that can operate at room temperature would be very beneficial for many applications in quantum technology. We show that the implementation of such sources is a realistic goal using solid-state emitters and ultrasmall mode volume cavities. We derive and analyze an expression for photon indistinguishability that accounts for relevant detrimental effects, such as plasmon-induced quenching and pure dephasing. We then provide the general cavity and emitter conditions required to achieve efficient indistinguishable photon emission and also discuss constraints due to phonon sideband emission. Using these conditions, we propose that a nanodiamond negatively charged silicon-vacancy center combined with a plasmonic-Fabry-Pérot hybrid cavity is an excellent candidate system.

  7. Single-mode annular chirally-coupled core fibers for fiber lasers

    Science.gov (United States)

    Zhang, Haitao; Hao, He; He, Linlu; Gong, Mali

    2018-03-01

    Chirally-coupled core (CCC) fiber can transmit single fundamental mode and effectively suppresses higher-order mode (HOM) propagation, thus improve the beam quality. However, the manufacture of CCC fiber is complicated due to its small side core. To decrease the manufacture difficulty in China, a novel fiber structure is presented, defined as annular chirally-coupled core (ACCC) fiber, replacing the small side core by a larger side annulus. In this paper, we designed the fiber parameters of this new structure, and demonstrated that the new structure has a similar property of single mode with traditional CCC fiber. Helical coordinate system was introduced into the finite element method (FEM) to analyze the mode field in the fiber, and the beam propagation method (BPM) was employed to analyze the influence of the fiber parameters on the mode loss. Based on the result above, the fiber structure was optimized for efficient single-mode transmission, in which the core diameter is 35 μm with beam quality M2 value of 1.04 and an optical to optical conversion efficiency of 84%. In this fiber, fundamental mode propagates in an acceptable loss, while the HOMs decay rapidly.

  8. Processing of complex shapes with single-mode resonant frequency microwave applicators

    International Nuclear Information System (INIS)

    Fellows, L.A.; Delgado, R.; Hawley, M.C.

    1994-01-01

    Microwave processing is an alternative to conventional composite processing techniques. Single-mode microwave applicators efficiently couple microwave energy into the composite. The application of the microwave energy is greatly affected by the geometry of the composite. In the single mode microwave applicator, two types of modes are available. These modes are best suited to processing flat planar samples or cylindrical samples with geometries that align with the electric fields. Mode-switching is alternating between different electromagnetic modes with the intelligent selection of the modes to alleviate undesirable temperature profiles. This method has improved the microwave heating profiles of materials with complex shapes that do not align with either type of electric field. Parts with two different complex geometries were fabricated from a vinyl toluene/vinyl ester resin with a continuous glass fiber reinforcement by autoclaving and by microwave techniques. The flexural properties of the microwave processed samples were compared to the flexural properties of autoclaved samples. The trends of the mechanical properties for the complex shapes were consistent with the results of experiments with flat panels. This demonstrated that mode-switching techniques are as applicable for the complex shapes as they are for the simpler flat panel geometry

  9. Single-molecule electronics: Cooling individual vibrational modes by the tunneling current.

    Science.gov (United States)

    Lykkebo, Jacob; Romano, Giuseppe; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C

    2016-03-21

    Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes can, in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions, or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular "heat sink" where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the "cooling mode," given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.

  10. A 66 fs highly stable single wall carbon nanotube mode locked fiber laser

    International Nuclear Information System (INIS)

    Yu, Zhenhua; Zhang, Xiao; Dong, Xinzheng; Tian, Jinrong; Song, Yanrong; Wang, Yonggang

    2014-01-01

    We demonstrate a highly stable mode locked fiber laser based on single wall carbon nanotubes. The mode locking is achieved by the evanescent field interaction of the propagating light with a single wall carbon nanotube saturable absorber in a microfiber. The pulse width is 66 fs, which, to the best of our knowledge, is the shortest pulse achieved in a carbon nanotube mode locked fiber laser. The maximum average output power is 26 mW, which is about 20 times larger than that of a typical carbon nanotube mode locked fiber laser. The center of the wavelength is 1555 nm, with 54 nm spectral width. The repetition rate is 146 MHz. To investigate the laser’s stability, the output pulses are monitored for 120 h and there is no significant degradation of the laser spectral width or shape. (paper)

  11. Self-Similar Nanocavity Design with Ultrasmall Mode Volume for Single-Photon Nonlinearities

    DEFF Research Database (Denmark)

    Choi, Hyeongrak; Heuck, Mikkel; Englund, Dirk R.

    2017-01-01

    We propose a photonic crystal nanocavity design with self-similar electromagnetic boundary conditions, achieving ultrasmall mode volume (V-eff). The electric energy density of a cavity mode can be maximized in the air or dielectric region, depending on the choice of boundary conditions. We illust...... at the single-photon level. These features open new directions in cavity quantum electrodynamics, spectroscopy, and quantum nonlinear optics....

  12. High performance mode locking characteristics of single section quantum dash lasers.

    Science.gov (United States)

    Rosales, Ricardo; Murdoch, S G; Watts, R T; Merghem, K; Martinez, Anthony; Lelarge, Francois; Accard, Alain; Barry, L P; Ramdane, Abderrahim

    2012-04-09

    Mode locking features of single section quantum dash based lasers are investigated. Particular interest is given to the static spectral phase profile determining the shape of the mode locked pulses. The phase profile dependence on cavity length and injection current is experimentally evaluated, demonstrating the possibility of efficiently using the wide spectral bandwidth exhibited by these quantum dash structures for the generation of high peak power sub-picosecond pulses with low radio frequency linewidths.

  13. Wavelength-selectable and steady single-mode erbium-doped fiber multiple ring laser

    Science.gov (United States)

    Yeh, Chien-Hung; Yang, Zi-Qing; Huang, Tzu-Jung; Chow, Chi-Wai; Chen, Jing-Heng; Chen, Kun-Huang

    2017-11-01

    To achieve a stable and selectable C-band erbium-doped fiber (EDF) laser with single-longitudinal-mode output, a multiple ring architecture is proposed and demonstrated experimentally. In this work, we design a passively quadruple-ring structure in the cavity of an EDF laser to produce a Vernier effect with a mode filter for suppressing the multimode spikes significantly. In addition, the output performance and stability of the proposed EDF ring laser are discussed.

  14. Investigation of single lateral mode for 852nm diode lasers with ridge waveguide design

    Science.gov (United States)

    Liu, Chu; Guan, Baolu; Mi, Guoxin; Liao, Yiru; Liu, Zhenyang; Li, Jianjun; Xu, Chen

    2016-11-01

    852nm Narrow linewidth lasers can be widely used in the field of ultra-fine spectrum measurement, Cs atomic clock control, satellite and optical fiber communication and so on. Furthermore, the stability of the single lateral mode is a very important condition to guarantee the narrow linewidth lasers. Here we investigate experimentally the influence of the narrow ridge structure and asymmetrical waveguide design on the stability single lateral mode of an 852nm diode laser. According to the waveguide theoretical analysis, ridge mesa etch depth (Δη , related to the refractive index difference of parallel to the junction) and ridge mesa width (the narrower the more control force to low order mode) are the main elements for lateral modes. In this paper, we designed different structures to investigate and verify major factors for lateral mode by experiment, and to confirm our thought. Finally, the 5μm mesa ridge laser, 800nm etch depth, with groove structure obtains excellent steady single lateral mode output by 150mA operating current and 30°C temperature. The optical spectrum FWHM is 0.5nm and side mode suppression ratio is 27dBm with uncoated. The laser with 1mm cavity length showed the threshold current of 50mA, a lasing wavelength of λ = 852.6nm, slope efficiency of above 0.7mW/mA. We accomplished single lateral mode of ridge waveguide edge-emitting lasers which can also be used as a laser source in the ultra-narrow linewidth external cavity laser system.

  15. Development of a 10-decade single-mode reactor flux monitoring system

    International Nuclear Information System (INIS)

    Valentine, K.H.; Shepard, R.L.; Falter, K.G.; Reese, W.B.

    1988-01-01

    Conventional wide-range neutron channels employ three optional modes to monitor the required flux range from source levels to full power (typically 10 or more decades). Difficult calibrations are necessary to provide a continuous output signal when such a system switches from counting mode in the source range to mean-square voltage mode in the midrange to dc current mode in the power range. In an ORNL proof-of-principle test, a method of extended range counting was implemented with a fission counter and conventional wide-band pulse processing electronics to provide a single-mode, monotonically increasing signal that spanned /approximately 10/ decades of neutron flux. Ongoing work includes design, fabrication, and testing of a comlpete neutron flux monitoring system suitable for advanced liquid metal reactor designs. 6 refs., 4 figs

  16. A Lifecycle Emissions Model (LEM): Lifecycle Emissions from Transportation Fuels, Motor Vehicles, Transportation Modes, Electricity Use, Heating and Cooking Fuels, and Materials, APPENDIX A: Energy Use and Emissions from the Lifecycle of Diesel-Like Fuels Derived From Biomass

    OpenAIRE

    Delucchi, Mark; Lipman, Timothy

    2003-01-01

    An Appendix to the Report, “A Lifecycle Emissions Model (LEM): Lifecycle Emissions From Transportation Fuels, Motor Vehicles, Transportation Modes, Electricity Use, Heating and Cooking Fuels, and Materialsâ€

  17. Sensitivity estimation in time-of-flight list-mode positron emission tomography.

    Science.gov (United States)

    Herraiz, J L; Sitek, A

    2015-11-01

    An accurate quantification of the images in positron emission tomography (PET) requires knowing the actual sensitivity at each voxel, which represents the probability that a positron emitted in that voxel is finally detected as a coincidence of two gamma rays in a pair of detectors in the PET scanner. This sensitivity depends on the characteristics of the acquisition, as it is affected by the attenuation of the annihilation gamma rays in the body, and possible variations of the sensitivity of the scanner detectors. In this work, the authors propose a new approach to handle time-of-flight (TOF) list-mode PET data, which allows performing either or both, a self-attenuation correction, and self-normalization correction based on emission data only. The authors derive the theory using a fully Bayesian statistical model of complete data. The authors perform an initial evaluation of algorithms derived from that theory and proposed in this work using numerical 2D list-mode simulations with different TOF resolutions and total number of detected coincidences. Effects of randoms and scatter are not simulated. The authors found that proposed algorithms successfully correct for unknown attenuation and scanner normalization for simulated 2D list-mode TOF-PET data. A new method is presented that can be used for corrections for attenuation and normalization (sensitivity) using TOF list-mode data.

  18. Sensitivity estimation in time-of-flight list-mode positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Herraiz, J. L. [Madrid-MIT M+Visión Consortium, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and Grupo de Física Nuclear, Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, CEI Moncloa, Madrid 28040 (Spain); Sitek, A., E-mail: sarkadiu@gmail.com [Center for Advanced Medical Imaging Sciences, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States)

    2015-11-15

    Purpose: An accurate quantification of the images in positron emission tomography (PET) requires knowing the actual sensitivity at each voxel, which represents the probability that a positron emitted in that voxel is finally detected as a coincidence of two gamma rays in a pair of detectors in the PET scanner. This sensitivity depends on the characteristics of the acquisition, as it is affected by the attenuation of the annihilation gamma rays in the body, and possible variations of the sensitivity of the scanner detectors. In this work, the authors propose a new approach to handle time-of-flight (TOF) list-mode PET data, which allows performing either or both, a self-attenuation correction, and self-normalization correction based on emission data only. Methods: The authors derive the theory using a fully Bayesian statistical model of complete data. The authors perform an initial evaluation of algorithms derived from that theory and proposed in this work using numerical 2D list-mode simulations with different TOF resolutions and total number of detected coincidences. Effects of randoms and scatter are not simulated. Results: The authors found that proposed algorithms successfully correct for unknown attenuation and scanner normalization for simulated 2D list-mode TOF-PET data. Conclusions: A new method is presented that can be used for corrections for attenuation and normalization (sensitivity) using TOF list-mode data.

  19. Facile synthesis of graphene on single mode fiber via chemical vapor deposition

    International Nuclear Information System (INIS)

    Zhang, C.; Man, B.Y.; Jiang, S.Z.; Yang, C.; Liu, M.; Chen, C.S.; Xu, S.C.; Feng, D.J.; Bi, D.; Liu, F.Y.; Qiu, H.W.

    2014-01-01

    Direct deposition of graphene film on the standard single mode fiber is offered using a Cu-vapor-assisted chemical vapor deposition system. The gas flow of H 2 and Ar before the growth process plays a crucial role for the direct deposition of the graphene film and the layers of the graphene can be controlled by the growth time. With a large gas flow, Cu atoms are carried off with the gas flow and hard to deposit on the surface of the single mode fiber before the growth process. Consequently, uniform graphene film is obtained in this case. On the contrary, with a lower one, Cu atoms is facile to deposit on the surface of the single mode fiber and form nanodots acting as active catalytic sites for the growth of carbon nanotubes. This method presents us a promising transfer-free technique for fabrication of the photonic applications.

  20. Utilizing wheel-ring architecture for stable and selectable single-longitudinal-mode erbium fiber laser

    Science.gov (United States)

    Yeh, Chien-Hung; Yang, Zi-Qing; Huang, Tzu-Jung; Chow, Chi-Wai

    2018-03-01

    To achieve a steady single-longitudinal-mode (SLM) erbium-doped fiber (EDF) laser, the wheel-ring architecture is proposed in the laser cavity. According to Vernier effect, the proposed wheel-ring can produce three different free spectrum ranges (FSRs) to serve as the mode-filter for suppressing the densely multi-longitudinal-mode (MLM). Here, to complete wavelength-tunable EDF laser, an optical tunable bandpass filter (OTBF) is utilized inside the cavity for tuning arbitrarily. In addition, the entire output performances of the proposed EDF wheel-ring laser are also discussed and analyzed experimentally.

  1. Studies of new modes of radioactive decay by spontaneous emission of complex nuclei

    International Nuclear Information System (INIS)

    Barwick, S.W.; Hulet, E.K.; Moody, K.; Price, P.B.; Ravn, H.L.

    1990-01-01

    Impressive progress has been made in the two years since Rose and Jones first reported the novel spontaneous decay mode 223 Ra → 14 C + 209 Pb. Since then, the isotopes 222 Ra, 224 Ra, and 226 Ra have been observed to emit 14 C, and stringent upper limits have been set on branching ratios B( 14 C/α) for 221 Ra and 225 Ac. The discoveries of emission of 24 Ne from 232 U, and 231 Pa, and 233 U show that the phenomenon of heavy ion emission is a general one. A goal of recent experiments by the authors collaboration is to test models that differ by as much as 10 5 in predicted half-lives for the emission of complex nuclei with Z ≥ 12. Due to small branching ratios B approx-lt 10 -14 , and large fission background, they are developing new techniques to insure reliable identification of such rare decay modes. Experimental support for the unified models of alpha decay, complex nuclei emission, and spontaneous fission are addressed

  2. PERFORMANCE, EMISSION, AND COMBUSTION CHARACTERISTICS OF A CI ENGINE USING LIQUID PETROLEUM GAS AND NEEM OIL IN DUAL FUEL MODE

    Directory of Open Access Journals (Sweden)

    Palanimuthu Vijayabalan

    2010-01-01

    Full Text Available Increased environmental awareness and depletion of resources are driving the industries to develop viable alternative fuels like vegetable oils, compresed natural gas, liquid petroleum gas, producer gas, and biogas in order to provide suitable substitute to diesel for compression ignition engine. In this investigation, a single cylinder, vertical, air-cooled diesel engine was modified to use liquid petroleum gas in dual fuel mode. The liquefied petroleum gas, was mixed with air and supplied through intake manifold. The liquid fuel neem oil or diesel was injected into the combustion chamber. The performance, emission, and combustion characteristics were studied and compared for neat fuel and dual fuel mode. The experimental results on dual fuel engine show a reduction in oxides of nitrogen up to 70% of the rated power and smoke in the entire power range. However the brake thermal efficiency was found decreased in low power range due to lower calorific value of liquid petroleum gas, and increase in higher power range due to the complete burning of liquid petroleum gas. Hydrocarbon and carbon monoxide emissions were increased significantly at lower power range and marginal variation in higher power range.

  3. Single photon emission computed tomography of the liver

    International Nuclear Information System (INIS)

    Makler, P.T. Jr.

    1988-01-01

    Single photon emission computed tomography (SPECT) of the liver has been introduced in order to improve sensitivity and localization of space-occupying lesions. There have been numerous reports on the usefulness of the technique, as well as extensive analyses of its technical drawbacks. In general, SPECT provides a more accurate estimation of defect size than does conventional planar scintigraphy for cases in which one wishes to evaluate changes in lesion size due to therapy. The presence of a superimposed parenchymal disease, however, remains a major problem, which will only be resolved by a scanning technique that specifically detects the disease process of concern (hot spot imaging) rather than displacement of normal tissue (cold spot imaging)

  4. Single photon emission computed tomography in AIDS dementia complex

    International Nuclear Information System (INIS)

    Pohl, P.; Vogl, G.; Fill, H.; Roessler, H.Z.; Zangerle, R.; Gerstenbrand, F.

    1988-01-01

    Single photon emission computed tomography (SPECT) studies were performed in AIDS dementia complex using IMP in 12 patients (and HM-PAO in four of these same patients). In all patients, SPECT revealed either multiple or focal uptake defects, the latter corresponding with focal signs or symptoms in all but one case. Computerized tomography showed a diffuse cerebral atrophy in eight of 12 patients, magnetic resonance imaging exhibited changes like atrophy and/or leukoencephalopathy in two of five cases. Our data indicate that both disturbance of cerebral amine metabolism and alteration of local perfusion share in the pathogenesis of AIDS dementia complex. SPECT is an important aid in the diagnosis of AIDS dementia complex and contributes to the understanding of the pathophysiological mechanisms of this disorder

  5. Non-classical light emission from single conjugated polymers

    Science.gov (United States)

    Hollars, Christopher; Lane, Stephen; Huser, Thomas

    2002-03-01

    Photon-antibunching from single, isolated molecules of collapsed-chain poly[2-methoxy,5-(2’-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) has been observed using confocal microscopy techniques. Efficient inter-segment energy transfer in collapsed-chain conjugated polymers leads to emission from an average of only 2-3 active sites on a polymer chain that is composed of hundreds of quasi-chromophores. These few centers consist of the segments with the lowest excitation energy and are supplied by the efficient light-harvesting and energy transfer of the surrounding higher-energy segments. This effect depends on the conformation of the polymer molecules, which is controlled by solvent polarity. These results provide new insight into the controversial photophysics of conjugated polymers and their application in optoelectronic devices.

  6. Single nucleon emission in relativistic nucleus-nucleus reactions

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Significant discrepancies between theory and experiment have previously been noted for nucleon emission via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work investigates the hypothesis that these discrepancies have arisen due to uncertainties about how to deduce the experimental electromagnetic cross section from the total measured cross section. An optical-model calculation of single neutron removal is added to electromagnetic cross sections and compared to the total experimental cross sections. Good agreement is found thereby resolving some of the earlier noted discrepancies. A detailed comparison to the recent work of Benesh, Cook, and Vary is made for both the impact parameter and the nuclear cross section. Good agreement is obtained giving an independent confirmation of the parameterized formulas developed by those authors

  7. Super-resolution from single photon emission: toward biological application

    Science.gov (United States)

    Moreva, E.; Traina, P.; Forneris, J.; Ditalia Tchernij, S.; Guarina, L.; Franchino, C.; Picollo, F.; Ruo Berchera, I.; Brida, G.; Degiovanni, I. P.; Carabelli, V.; Olivero, P.; Genovese, M.

    2017-08-01

    Properties of quantum light represent a tool for overcoming limits of classical optics. Several experiments have demonstrated this advantage ranging from quantum enhanced imaging to quantum illumination. In this work, experimental demonstration of quantum-enhanced resolution in confocal fluorescence microscopy will be presented. This is achieved by exploiting the non-classical photon statistics of fluorescence emission of single nitrogen-vacancy (NV) color centers in diamond. By developing a general model of super-resolution based on the direct sampling of the kth-order autocorrelation function of the photoluminescence signal, we show the possibility to resolve, in principle, arbitrarily close emitting centers. Finally, possible applications of NV-based fluorescent nanodiamonds in biosensing and future developments will be presented.

  8. Single-mode hole-assisted fiber as a bending-loss insensitive fiber

    Science.gov (United States)

    Nakajima, Kazuhide; Shimizu, Tomoya; Matsui, Takashi; Fukai, Chisato; Kurashima, Toshio

    2010-12-01

    We investigate the design and characteristics of a single-mode and low bending loss HAF both numerically and experimentally. An air filling fraction S is introduced to enable us to design a HAF with desired characteristics more easily. We show that we can expect to realize a single-mode and low bending loss HAF by considering the S dependence of the bending loss α b and cutoff wavelength λ c as well as their relative index difference Δ dependence. We also show that the mode-field diameter (MFD) and chromatic dispersion characteristics of the single-mode and low bending loss HAF can be tailored by optimizing the distance between the core and the air holes. We also investigate the usefulness of the fabricated HAFs taking the directly modulated transmission and multipath interference (MPI) characteristics into consideration. We show that the designed HAF has sufficient applicability to both analog and digital transmission systems. Our results reveal that the single-mode and low bending loss HAF is beneficial in terms of developing a future fiber to the home (FTTH) network as well as for realizing flexible optical wiring.

  9. Large-core single-mode rib SU8 waveguide using solvent-assisted microcontact molding.

    Science.gov (United States)

    Huang, Cheng-Sheng; Wang, Wei-Chih

    2008-09-01

    This paper describes a novel fabrication technique for constructing a polymer-based large-core single-mode rib waveguide. A negative tone SU8 photoresist with a high optical transmission over a large wavelength range and stable mechanical properties was used as a waveguide material. A waveguide was constructed by using a polydimethylsiloxane stamp combined with a solvent-assisted microcontact molding technique. The effects on the final pattern's geometry of four different process conditions were investigated. Optical simulations were performed using beam propagation method software. Single-mode beam propagation was observed at the output of the simulated waveguide as well as the actual waveguide through the microscope image.

  10. Second-order interference of two independent and tunable single-mode continuous-wave lasers

    International Nuclear Information System (INIS)

    Liu Jianbin; Chen Hui; Zheng Huaibin; Xu Zhuo; Wei Dong; Zhou Yu; Gao Hong; Li Fu-Li

    2016-01-01

    The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by employing two-photon interference in Feynman’s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra. (paper)

  11. The second-order interference of two independent single-mode He-Ne lasers

    Science.gov (United States)

    Liu, Jianbin; Le, Mingnan; Bai, Bin; Wang, Wentao; Chen, Hui; Zhou, Yu; Li, Fu-li; Xu, Zhuo

    2015-09-01

    The second-order spatial and temporal interference patterns with two independent single-mode continuous-wave He-Ne lasers are observed when these two lasers are incident to two adjacent input ports of a 1:1 non-polarizing beam splitter, respectively. Two-photon interference based on the superposition principle in Feynman's path integral theory is employed to interpret the experimental results. The conditions to observe the second-order interference pattern with two independent single-mode continuous-wave lasers are discussed. It is concluded that frequency stability is important to observe the second-order interference pattern with two independent light beams.

  12. Excitation of contained modes by high energy nuclei and correlated cyclotron emission

    International Nuclear Information System (INIS)

    Coppi, B.; Penn, G.; Riconda, C.

    1997-01-01

    In experiments with fusing plasmas, enhanced radiation emission at the harmonics of the cyclotron frequency of fusion reaction products has been observed. A theory is presented that explains key features of these observations and indicates the possibility of extracting significant information about the fusion product population distribution, both in velocity space and over the plasma cross section. The considered model is consistent in particular with the fact that, in DT plasmas, the radiation peaks occur at frequencies corresponding to harmonics of the α particles cyclotron frequency Ω a evaluated at the outer edge of the plasma column, and that a transition to a open-quotes continuumclose quotes spectrum at high frequencies (ω approx-gt 7Ω α ) can be identified. In this model, the radiation is the result of the excitation of radially open-quotes containedclose quotes modes which are driven unstable by the fusion products. The modes considered to be responsible for the discrete part of the spectrum are spatially localized near the plasma edge. The radial containment, which is associated mainly with the inhomogeneity of the plasma density, is in fact a fundamental characteristic since only contained modes can grow out of a relatively weak mode-particle interaction and justify the detected emission power levels. The contained mode is a solution to a set of macroscopic equations, in which the electron motion is tied to that of the magnetic field (Hall effect). The growth rate has been evaluated considering the particle orbits in a toroidal confinement configuration and modelling the distribution function of the interacting particles with the energy at birth before slowing down occurs. The growth rate depends linearly on the α-particle density and can be larger than, or of the order of, the bounce frequency of the magnetically trapped α-particles, which can have a resonant interaction with the mode. According to the theoretical model presented, the discrete

  13. A study of tearing modes via electron cyclotron emission from tokamak plasmas

    International Nuclear Information System (INIS)

    Ren, C.

    1998-07-01

    This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm's law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented

  14. A study of tearing modes via electron cyclotron emission from tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Chuang [Univ. of Wisconsin, Madison, WI (United States)

    1998-07-01

    This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm`s law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented.

  15. Proceedings of clinical SPECT [single photon emission computed tomography] symposium

    International Nuclear Information System (INIS)

    1986-09-01

    It has been five years since the last in-depth American College of Nuclear Physicians/Society of Nuclear Medicine Symposium on the subject of single photon emission computed tomography (SPECT) was held. Because this subject was nominated as the single most desired topic we have selected SPECT imaging as the basis for this year's program. The objectives of this symposium are to survey the progress of SPECT clinical applications that have taken place over the last five years and to provide practical and timely guidelines to users of SPECT so that this exciting imaging modality can be fully integrated into the evaluation of pathologic processes. The first half was devoted to a consideration of technical factors important in SPECT acquisition and the second half was devoted to those organ systems about which sufficient clinical SPECT imaging data are available. With respect to the technical aspect of the program we have selected the key areas which demand awareness and attention in order to make SPECT operational in clinical practice. These include selection of equipment, details of uniformity correction, utilization of phantoms for equipment acceptance and quality assurance, the major aspect of algorithms, an understanding of filtered back projection and appropriate choice of filters and an awareness of the most commonly generated artifacts and how to recognize them. With respect to the acquisition and interpretation of organ images, the faculty will present information on the major aspects of hepatic, brain, cardiac, skeletal, and immunologic imaging techniques. Individual papers are processed separately for the data base

  16. 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.

  17. A portable optical emission spectroscopy-cavity ringdown spectroscopy dual-mode plasma spectrometer for measurements of environmentally important trace heavy metals: Initial test with elemental Hg

    Science.gov (United States)

    Sahay, Peeyush; Scherrer, Susan T.; Wang, Chuji

    2012-09-01

    A portable optical emission spectroscopy-cavity ringdown spectroscopy (OES-CRDS) dual-mode plasma spectrometer is described. A compact, low-power, atmospheric argon microwave plasma torch (MPT) is utilized as the emission source when the spectrometer is operating in the OES mode. The same MPT serves as the atomization source for ringdown measurements in the CRDS mode. Initial demonstration of the instrument is carried out by observing OES of multiple elements including mercury (Hg) in the OES mode and by measuring absolute concentrations of Hg in the metastable state 6s6p 3P0 in the CRDS mode, in which a palm-size diode laser operating at a single wavelength 405 nm is incorporated in the spectrometer as the light source. In the OES mode, the detection limit for Hg is determined to be 44 parts per 109 (ppb). A strong radiation trapping effect on emission measurements of Hg at 254 nm is observed when the Hg solution concentration is higher than 50 parts per 106 (ppm). The radiation trapping effect suggests that two different transition lines of Hg at 253.65 nm and 365.01 nm be selected for emission measurements in lower (50 ppm), respectively. In the CRDS mode, the detection limit of Hg in the metastable state 6s6p 3P0 is achieved to be 2.24 parts per 1012 (ppt) when the plasma is operating at 150 W with sample gas flow rate of 480 mL min-1; the detection limit corresponds to 50 ppm in Hg sample solution. Advantage of this novel spectrometer has two-fold, it has a large measurement dynamic range, from a few ppt to hundreds ppm and the CRDS mode can serve as calibration for the OES mode as well as high sensitivity measurements. Measurements of seven other elements, As, Cd, Mn, Ni, P, Pb, and Sr, using the OES mode are also carried out with detection limits of 1100, 33, 30, 144, 576, 94, and 2 ppb, respectively. Matrix effect in the presence of other elements on Hg measurements has been found to increase the detection limit to 131 ppb. These elements in lower

  18. Dual-mode optical microscope based on single-pixel imaging

    OpenAIRE

    Rodríguez Jiménez, Angel David; Clemente Pesudo, Pedro Javier; Tajahuerce, Enrique; Lancis Sáez, Jesús

    2016-01-01

    We demonstrate an inverted microscope that can image specimens in both reflection and transmission modes simultaneously with a single light source. The microscope utilizes a digital micromirror device (DMD) for patterned illumination altogether with two single-pixel photosensors for efficient light detection. The system, a scan-less device with no moving parts, works by sequential projection of a set of binary intensity patterns onto the sample that are codified onto a modified commercial DMD...

  19. Computational investigation of single mode vs multimode Rayleigh endash Taylor seeding in Z-pinch implosions

    International Nuclear Information System (INIS)

    Douglas, M.R.; Deeney, C.; Roderick, N.F.

    1998-01-01

    A series of two-dimensional magnetohydrodynamic calculations have been carried out to investigate single and multimode growth and mode coupling for magnetically-driven Rayleigh endash Taylor instabilities in Z pinches. Wavelengths ranging from 5.0 mm down to 1.25 mm were considered. Such wavelengths are comparable to those observed at stagnation using a random density open-quotes seedingclose quotes method. The calculations show that wavelengths resolved by less than 10 cells exhibit an artificial decrease in initial Fourier spectrum amplitudes and a reduction in the corresponding amplitude growth. Single mode evolution exhibits linear exponential growth and the development of higher harmonics as the mode transitions into the nonlinear phase. The mode growth continues to exponentiate but at a slower rate than determined by linear hydrodynamic theory. In the two and three mode case, there is clear evidence of mode coupling and inverse cascade. In addition, distinct modal patterns are observed late in the implosion, resulting from finite shell thickness and magnetic field effects. copyright 1998 American Institute of Physics. thinsp

  20. 107.5 Gb/s 850 nm multi- and single-mode VCSEL transmission over 10 and 100 m of multi-mode fiber

    DEFF Research Database (Denmark)

    Puerta Ramírez, Rafael; Agustin, M.; Chorchos, L.

    2016-01-01

    First time successful 107.5 Gb/s MultiCAP 850 nm OM4 MMF transmissions over 10 m with multi-mode VCSEL and up to 100 m with single-mode VCSEL are demonstrated, with BER below 7% overhead FEC limit measured for each case.......First time successful 107.5 Gb/s MultiCAP 850 nm OM4 MMF transmissions over 10 m with multi-mode VCSEL and up to 100 m with single-mode VCSEL are demonstrated, with BER below 7% overhead FEC limit measured for each case....

  1. Probing quantum entanglement in the Schwarzschild space-time beyond the single-mode approximation

    Science.gov (United States)

    He, Juan; Ding, Zhi-Yong; Ye, Liu

    2018-05-01

    In this paper, we deduce the vacuum structure for Dirac fields in the background of Schwarzschild space-time beyond the single-mode approximation and discuss the performance of quantum entanglement between particle and antiparticle modes of a Dirac field with Hawking effect. It is shown that Hawking radiation does not always destroy the physically accessible entanglement, and entanglement amplification may happen in some cases. This striking result is different from that of the single-mode approximation, which holds that the Hawking radiation can only destroy entanglement. Lastly, we analyze the physically accessible entanglement relation outside the event horizon and demonstrate that the monogamy inequality is constantly established regardless of the choice of given parameters.

  2. Quantum teleportation via noisy bipartite and tripartite accelerating quantum states: beyond the single mode approximation

    Science.gov (United States)

    Zounia, M.; Shamirzaie, M.; Ashouri, A.

    2017-09-01

    In this paper quantum teleportation of an unknown quantum state via noisy maximally bipartite (Bell) and maximally tripartite (Greenberger-Horne-Zeilinger (GHZ)) entangled states are investigated. We suppose that one of the observers who would receive the sent state accelerates uniformly with respect to the sender. The interactions of the quantum system with its environment during the teleportation process impose noises. These (unital and nonunital) noises are: phase damping, phase flip, amplitude damping and bit flip. In expressing the modes of the Dirac field used as qubits, in the accelerating frame, the so-called single mode approximation is not imposed. We calculate the fidelities of teleportation, and discuss their behaviors using suitable plots. The effects of noise, acceleration and going beyond the single mode approximation are discussed. Although the Bell states bring higher fidelities than GHZ states, the global behaviors of the two quantum systems with respect to some noise types, and therefore their fidelities, are different.

  3. Practical Considerations Concerning the Interleaved Transition Mode Single-stage Ballast

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Kjær, Søren Bækhøj; Munk-Nielsen, Stig

    2002-01-01

    The aim of this paper is to present a novel single-stage interleaved ballast focusing on practical design aspects like: key current expression, overall losses, harmonic analysis of the differential-mode EMI current and preheating ballast function. A new preheating method is also presented. A PSPICE...

  4. Analytical Expression for the Electric Field of the Single Mode Laser ...

    African Journals Online (AJOL)

    The simplest model of the laser is that of a single mode system homogenously broadened. The dynamical behavior of this laser is described by three differential equations, called Haken-Lorenz equations[1], similar to the Lorenz model [1] already known to predict deterministic chaos. In previous recent work [5-7] we have ...

  5. Optical Field-Strength Polarization of Two-Mode Single-Photon States

    Science.gov (United States)

    Linares, J.; Nistal, M. C.; Barral, D.; Moreno, V.

    2010-01-01

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of…

  6. Current Mode Full-Wave Rectifier Based on a Single MZC-CDTA

    Directory of Open Access Journals (Sweden)

    Neeta Pandey

    2013-01-01

    Full Text Available This paper presents a current mode full-wave rectifier based on single modified Z copy current difference transconductance amplifier (MZC-CDTA and two switches. The circuit is simple and is suitable for IC implementation. The functionality of the circuit is verified with SPICE simulation using 0.35 μm TSMC CMOS technology parameters.

  7. Flexible long-range surface plasmon polariton single-mode waveguide for optical interconnects

    DEFF Research Database (Denmark)

    Vernoux, Christian; Chen, Yiting; Markey, Laurent

    2018-01-01

    We present the design, fabrication and characterization of long-range surface plasmon polariton waveguide arrays with materials, mainly silicones, carefully selected with the aim to be used as mechanically flexible single-mode optical interconnections, the socalled "plasmonic arc" working at 1.55μm...

  8. Single-mode very wide tunability in laterally coupled semiconductor lasers with electrically controlled reflectivities

    Science.gov (United States)

    Griffel, Giora; Chen, Howard Z.; Grave, Ilan; Yariv, Amnon

    1991-04-01

    The operation of a novel multisection structure comprised of laterally coupled gain-guided semiconductor lasers is demonstrated. It is shown that tunable single longitudinal mode operation can be achieved with a high degree of frequency selectivity. The device has a tuning range of 14.5 nm, the widest observed to date in a monolithic device.

  9. Extremely low-loss single-mode photonic crystal fiber in the terahertz regime

    DEFF Research Database (Denmark)

    Islam, Raonaqul; Hasanuzzaman, G. K M; Sadath, Md Anwar

    2015-01-01

    This paper presents an updated design and numerical characterization of a rotated porous-core hexagonal photonic crystal fiber (PCF) for single-mode terahertz (THz) wave guidance. The simulation results are found using an efficient finite element method (FEM) which show a better and ultra-low eff...

  10. Efficient coupling of a single diamond color center to propagating plasmonic gap modes

    DEFF Research Database (Denmark)

    Kumar, Shailesh; Huck, Alexander; Andersen, Ulrik L

    2013-01-01

    We report on coupling of a single nitrogen-vacancy (NV) center in a nanodiamond to the propagating gap mode of two parallel placed chemically grown silver nanowires. The coupled NV-center nanowire system is made by manipulating nanodiamonds and nanowires with the tip of an atomic force microscope...

  11. Single-mode 37-core fiber with a cladding diameter of 248 μm

    DEFF Research Database (Denmark)

    Sasaki, Y.; Takenaga, K.; Aikawa, K.

    2017-01-01

    A heterogeneous single-mode 37-core fiber with a cladding diameter of 248 μm is designed and fabricated. The fiber provides the highest core count and low total-crosstalk less than −20 dB/1000 km in C+L band....

  12. Image properties of list mode likelihood reconstruction for a rectangular positron emission mammography with DOI measurements

    International Nuclear Information System (INIS)

    Qi, Jinyi; Klein, Gregory J.; Huesman, Ronald H.

    2000-01-01

    A positron emission mammography scanner is under development at our Laboratory. The tomograph has a rectangular geometry consisting of four banks of detector modules. For each detector, the system can measure the depth of interaction information inside the crystal. The rectangular geometry leads to irregular radial and angular sampling and spatially variant sensitivity that are different from conventional PET systems. Therefore, it is of importance to study the image properties of the reconstructions. We adapted the theoretical analysis that we had developed for conventional PET systems to the list mode likelihood reconstruction for this tomograph. The local impulse response and covariance of the reconstruction can be easily computed using FFT. These theoretical results are also used with computer observer models to compute the signal-to-noise ratio for lesion detection. The analysis reveals the spatially variant resolution and noise properties of the list mode likelihood reconstruction. The theoretical predictions are in good agreement with Monte Carlo results

  13. Proceedings of clinical SPECT (single photon emission computed tomography) symposium

    Energy Technology Data Exchange (ETDEWEB)

    1986-09-01

    It has been five years since the last in-depth American College of Nuclear Physicians/Society of Nuclear Medicine Symposium on the subject of single photon emission computed tomography (SPECT) was held. Because this subject was nominated as the single most desired topic we have selected SPECT imaging as the basis for this year's program. The objectives of this symposium are to survey the progress of SPECT clinical applications that have taken place over the last five years and to provide practical and timely guidelines to users of SPECT so that this exciting imaging modality can be fully integrated into the evaluation of pathologic processes. The first half was devoted to a consideration of technical factors important in SPECT acquisition and the second half was devoted to those organ systems about which sufficient clinical SPECT imaging data are available. With respect to the technical aspect of the program we have selected the key areas which demand awareness and attention in order to make SPECT operational in clinical practice. These include selection of equipment, details of uniformity correction, utilization of phantoms for equipment acceptance and quality assurance, the major aspect of algorithms, an understanding of filtered back projection and appropriate choice of filters and an awareness of the most commonly generated artifacts and how to recognize them. With respect to the acquisition and interpretation of organ images, the faculty will present information on the major aspects of hepatic, brain, cardiac, skeletal, and immunologic imaging techniques. Individual papers are processed separately for the data base. (TEM)

  14. Mode division multiplexing technology for single-fiber optical trapping axial-position adjustment.

    Science.gov (United States)

    Liu, Zhihai; Wang, Lei; Liang, Peibo; Zhang, Yu; Yang, Jun; Yuan, Libo

    2013-07-15

    We demonstrate trapped yeast cell axial-position adjustment without moving the optical fiber in a single-fiber optical trapping system. The dynamic axial-position adjustment is realized by controlling the power ratio of the fundamental mode beam (LP01) and the low-order mode beam (LP11) generated in a normal single-core fiber. In order to separate the trapping positions produced by the two mode beams, we fabricate a special fiber tapered tip with a selective two-step method. A yeast cell of 6 μm diameter is moved along the optical axis direction for a distance of ~3 μm. To the best of our knowledge, this is the first demonstration of the trapping position adjustment without moving the fiber for single-fiber optical tweezers. The excitation and utilization of multimode beams in a single fiber constitutes a new development for single-fiber optical trapping and makes possible more practical applications in biomedical research fields.

  15. Benchmarking of Grid Fault Modes in Single-Phase Grid-Connected Photovoltaic Systems

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2013-01-01

    Pushed by the booming installations of singlephase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of Low Voltage Ride-Through (LVRT) and grid support...... phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant synchronization and control strategies are discussed. Some faulty modes are studied experimentally...... and provided at the end of this paper. It is concluded that there are extensive control possibilities in single-phase PV systems under grid faults. The Second Order General Integral based PLL technique might be the most promising candidate for future single-phase PV systems because of its fast adaptive...

  16. Frequency splitter based on the directional emission from surface modes in dielectric photonic crystal structures.

    Science.gov (United States)

    Tasolamprou, Anna C; Zhang, Lei; Kafesaki, Maria; Koschny, Thomas; Soukoulis, Costas M

    2015-06-01

    We demonstrate the numerical design and the experimental validation of frequency dependent directional emission from a dielectric photonic crystal structure. The wave propagates through a photonic crystal line-defect waveguide, while a surface layer at the termination of the photonic crystal enables the excitation of surface modes and a subsequent grating layer transforms the surface energy into outgoing propagating waves of the form of a directional beam. The angle of the beam is controlled by the frequency and the structure operates as a frequency splitter in the intermediate and far field region.

  17. Single photon emission computed tomography in lumbar degenerative spondylolisthesis

    International Nuclear Information System (INIS)

    Ito, S.; Muro, T.; Eisenstein, S.

    1998-01-01

    Analysis of single photon emission computed tomographic images and plain X-ray films of the lumbar vertebrae was performed in 15 patients with lumbar spondylosis and 15 patients with lumbar degenerative spondylolisthesis. The facet joint and osteophyte images were observed in particular, and the slipping ratio of spondylolisthetic vertebrae was determined. The slipping ratio of degenerative spondylolisthesis ranged from 11.8 % to 22.3 %. Hot uptake of 99mTc-HMDP by both L4-5 facet joints was significantly greater in the patients with degenerative spondylolisthesis than in those with lumbar spondylosis. The hot uptake by the osteophytes in lumbar spondylosis was nearly uniform among the three inferior segments, L3-4, L4-5 and L5-S, but was localized to the spondylolisthetic vertebrae, L4-5, or L5-S, in the patients with spondylolisthesis. Half of the osteophytes with hot uptake were assigned to the 3rd degree of Nathan's grading. It was suggested that stress was localized to the slipping vertebrae and their facet joints in patients with lumbar degenerative spondylolisthesis. (author)

  18. Visualization of portal venous system by single photon emission CT

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwagi, T; Ikawa, T; Azuma, M; Matsuda, H; Yoshioka, H; Mitsutani, N; Koizumi, T

    1987-03-01

    Single photon emission CT (SPECT) was performed for the intra-abdominal blood pool with /sup 99m/Tc autologous red blood cells (RBC) in 15 patients with liver cirrhosis. Twenty mCi of /sup 99m/Tc-RBC labeled by in vivo technique were administered intravenously and tomographic imaging of the intra-abdominal vascular blood pool was performed as follows. For each subject, 64 views were obtained over 360 deg of elliptic rotation at 30 seconds per view using a high resolution low energy parallel-hole collimator. Portal vein and portosystemic collaterals were clearly observed in coronal images. In 12 of 15 patients, portal vein was delineated. Portosystemic collaterals such as coronary vein, splenorenal shunt and umbilical vein were also shown in 12 patients. These images were consistent with images obtained by scintiphotosplenoportography or arterial portography. Therefore, it is considered that SPECT study for the intra-abdominal blood pool is clinically very useful for the diagnosis of abnormality of portal venous system in portal hypertension.

  19. Brain single photon emission computed tomography in neonates

    International Nuclear Information System (INIS)

    Denays, R.; Van Pachterbeke, T.; Tondeur, M.

    1989-01-01

    This study was designed to rate the clinical value of [ 123 I]iodoamphetamine (IMP) or [ 99m Tc] hexamethyl propylene amine oxyme (HM-PAO) brain single photon emission computed tomography (SPECT) in neonates, especially in those likely to develop cerebral palsy. The results showed that SPECT abnormalities were congruent in most cases with structural lesions demonstrated by ultrasonography. However, mild bilateral ventricular dilatation and bilateral subependymal porencephalic cysts diagnosed by ultrasound were not associated with an abnormal SPECT finding. In contrast, some cortical periventricular and sylvian lesions and all the parasagittal lesions well visualized in SPECT studies were not diagnosed by ultrasound scans. In neonates with subependymal and/or intraventricular hemorrhage the existence of a parenchymal abnormality was only diagnosed by SPECT. These results indicate that [ 123 I]IMP or [ 99m Tc]HM-PAO brain SPECT shows a potential clinical value as the neurodevelopmental outcome is clearly related to the site, the extent, and the number of cerebral lesions. Long-term clinical follow-up is, however, mandatory in order to define which SPECT abnormality is associated with neurologic deficit

  20. Efficient white organic light emission by single emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Young Wook; Chung, Choong-Heui; Lee, Jin Ho; Kim, Yong-Hae; Sohn, Choong-Yong; Kim, Bong-Chul; Hwang, Chi-Sun; Song, Yoon-Ho; Lim, Jongtae; Ahn, Young-Joo; Kang, Gi-Wook; Lee, Namheon; Lee, Changhee

    2003-02-24

    Stable organic white light-emitting diodes are successfully fabricated by a single organic white emitting layer, which is Bis (2-methyl-8-quinolinato) (triphenylsiloxy) aluminum (III) (SAlq) doped red fluorescent dye of 4-(dicyanomethylene)-2-tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)- 4H-pyran (DCJTB). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCJTB enables to obtain a stable white balanced light-emission by the DCJTB doping concentration of 0.5%. A device with the structure of ITO/TPD (50 nm)/SAlq:DCJTB (30 nm, 0.5%)/Alq{sub 3} (20 nm)/LiF (0.5 nm)/Al (110 nm) shows maximum luminance of 20 400 cd/m{sup 2} at 810 mA/cm{sup 2}, external quantum efficiency of 2% at 200 cd/m{sup 2} ({approx}3 mA/cm{sup 2}), power efficiency of 2.3 lm/W at 67 cd/m{sup 2} ({approx}1 mA/cm{sup 2}), and a Commission Internationale de l'Eclairage chromaticity coordinates of (0.34, 0.39) at 1.8 mA/cm{sup 2} to (0.31, 0.38) at 36 mA/cm{sup 2}.

  1. Single-Photon Emission Computed Tomography (SPECT) in childhood epilepsy

    International Nuclear Information System (INIS)

    Gulati, Sheffali; Kalra, Veena; Bal, C.S.

    2000-01-01

    The success of epilepsy surgery is determined strongly by the precise location of the epileptogenic focus. The information from clinical electrophysiological data needs to be strengthened by functional neuroimaging techniques. Single photon emission computed tomography (SPECT) available locally has proved useful as a localising investigation. It evaluates the regional cerebral blood flow and the comparison between ictal and interictal blood flow on SPECT has proved to be a sensitive nuclear marker for the site of seizure onset. Many studies justify the utility of SPECT in localising lesions to possess greater precision than interictal scalp EEG or anatomic neuroimaging. SPECT is of definitive value in temporal lobe epilepsy. Its role in extratemporal lobe epilepsy is less clearly defined. It is useful in various other generalized and partial seizure disorders including epileptic syndromes and helps in differentiating pseudoseizures from true seizures. The need for newer radiopharmaceutical agents with specific neurochemical properties and longer shelf life are under investigation. Subtraction ictal SPECT co-registered to MRI is a promising new modality. (author)

  2. Peristaltic modes of a single vortex in the Abelian Higgs model

    International Nuclear Information System (INIS)

    Kojo, Toru; Suganuma, Hideo; Tsumura, Kyosuke

    2007-01-01

    Using the Abelian Higgs model, we study the radial excitations of single vortex and their propagation modes along the vortex line. We call such beyond-stringy modes peristaltic modes of single vortex. With the profile of the static vortex, we derive the vortex-induced potential, i.e., single-particle potential for the Higgs and the photon field fluctuations around the static vortex, and investigate the coherently propagating fluctuations which correspond to the vibration of the vortex. We derive, analyze, and numerically solve the field equations of the Higgs and the photon field fluctuations around the static vortex with various Ginzburg-Landau parameter κ and topological charge n. Around the Bogomol'nyi-Prasad-Sommerfield value or critical coupling κ 2 =1/2, there appears a significant correlation between the Higgs and the photon field fluctuations mediated by the static vortex. As a result, for κ 2 =1/2, we find the characteristic new-type discrete pole of the peristaltic mode corresponding to the quasibound state of coherently fluctuating fields and the static vortex. We investigate its excitation energy, correlation energy of coherent fluctuations, spatial distributions, and the resulting magnetic flux behavior in detail. Our investigation covers not only usual type-II vortices with n=1 but also type-I and type-II vortices with n set-membership sign Z for the application to various general systems where the vortexlike objects behave as the essential degrees of freedom

  3. Single-Phase Microgrid with Seamless Transition Capabilities between Modes of Operation

    DEFF Research Database (Denmark)

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril

    2015-01-01

    with the secondary control loops that are used to synchronize the microgrid as a single unit to the grid. Simulation results are given that show the seamless transitions between the two modes without any disconnection times for the CC-VSIs and VC-VSIs connected to the microgrid.......Microgrids are an effective way to increase the penetration of DG into the grid. They are capable of operating either in grid-connected or in islanded mode thereby increasing the supply reliability for the end user. This paper focuses on achieving seamless transitions from islanded to grid-connected...

  4. Bend compensated large-mode-area fibers: achieving robust single-modedness with transformation optics.

    Science.gov (United States)

    Fini, John M; Nicholson, Jeffrey W

    2013-08-12

    Fibers with symmetric bend compensated claddings are proposed, and demonstrate performance much better than conventional designs. These fibers can simultaneously achieve complete HOM suppression, negligible bend loss, and mode area >1000 square microns. The robust single-modedness of these fibers offers a path to overcoming mode instability limits on high-power amplifiers and lasers. The proposed designs achieve many of the advantages of our previous (asymmetric) bend compensation strategy in the regime of moderately large area, and are much easier to fabricate and utilize.

  5. Effects of underwater turbulence on laser beam propagation and coupling into single-mode optical fiber.

    Science.gov (United States)

    Hanson, Frank; Lasher, Mark

    2010-06-01

    We characterize and compare the effects of turbulence on underwater laser propagation with theory. Measurements of the coupling efficiency of the focused beam into a single-mode fiber are reported. A simple tip-tilt control system, based on the position of the image centroid in the focal plane, was shown to maintain good coupling efficiency for a beam radius equal to the transverse coherence length, r(0). These results are relevant to high bandwidth communication technology that requires good spatial mode quality.

  6. Excitation of surface plasmon polariton modes with multiple nitrogen vacancy centers in single nanodiamonds

    International Nuclear Information System (INIS)

    Kumar, Shailesh; Lausen, Jens L; Andersen, Sebastian K H; Roberts, Alexander S; Radko, Ilya P; Bozhevolnyi, Sergey I; Garcia-Ortiz, Cesar E; Smith, Cameron L C; Kristensen, Anders

    2016-01-01

    Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple NV centers in nanodiamonds (NDs) are especially useful as biological fluorophores due to their chemical neutrality, brightness and room-temperature photostability. Furthermore, NDs containing multiple NV centers also have potential in high-precision magnetic field and temperature sensing. Coupling NV centers to propagating surface plasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices, allows enhanced fluorescence emission and collection which can further enhance the precision of NV-based sensors. Here, we investigate coupling of multiple NV centers in individual NDs to the SPP modes supported by silver surfaces protected by thin dielectric layers and by gold V-grooves (VGs) produced via the self-terminated silicon etching. In the first case, we concentrate on monitoring differences in fluorescence spectra obtained from a source ND, which is illuminated by a pump laser, and from a scattering ND illuminated only by the fluorescence-excited SPP radiation. In the second case, we observe changes in the average NV lifetime when the same ND is characterized outside and inside a VG. Fluorescence emission from the VG terminations is also observed, which confirms the NV coupling to the VG-supported SPP modes. (paper)

  7. Excitation of surface plasmon polariton modes with multiple nitrogen vacancy centers in single nanodiamonds

    Science.gov (United States)

    Kumar, Shailesh; Lausen, Jens L.; Garcia-Ortiz, Cesar E.; Andersen, Sebastian K. H.; Roberts, Alexander S.; Radko, Ilya P.; Smith, Cameron L. C.; Kristensen, Anders; Bozhevolnyi, Sergey I.

    2016-02-01

    Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple NV centers in nanodiamonds (NDs) are especially useful as biological fluorophores due to their chemical neutrality, brightness and room-temperature photostability. Furthermore, NDs containing multiple NV centers also have potential in high-precision magnetic field and temperature sensing. Coupling NV centers to propagating surface plasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices, allows enhanced fluorescence emission and collection which can further enhance the precision of NV-based sensors. Here, we investigate coupling of multiple NV centers in individual NDs to the SPP modes supported by silver surfaces protected by thin dielectric layers and by gold V-grooves (VGs) produced via the self-terminated silicon etching. In the first case, we concentrate on monitoring differences in fluorescence spectra obtained from a source ND, which is illuminated by a pump laser, and from a scattering ND illuminated only by the fluorescence-excited SPP radiation. In the second case, we observe changes in the average NV lifetime when the same ND is characterized outside and inside a VG. Fluorescence emission from the VG terminations is also observed, which confirms the NV coupling to the VG-supported SPP modes.

  8. Design optimization of the distributed modal filtering rod fiber for increasing single mode bandwidth

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko

    2012-01-01

    . Large preform tolerances are compensated during the fiber draw resulting in ultra low NA fibers with very large cores. In this paper, design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared...... LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled from the outer fiber. However, achieving ultra low NA for single-mode (SM) guidance is challenging, and thus different design strategies must be applied to filter out higher order modes (HOMs). The novel...... distributed modal filtering (DMF) design presented here enables SM guidance, and previous results have shown a SM mode field diameter of 60 μm operating in a 20 nm SM bandwidth. The DMF rod fiber has high index ring-shaped inclusions acting as resonators enabling SM guidance through modal filtering of HOMs...

  9. Three-dimensional single-mode nonlinear ablative Rayleigh-Taylor instability

    International Nuclear Information System (INIS)

    Yan, R.; Aluie, H.; Betti, R.; Sanz, J.; Liu, B.; Frank, A.

    2016-01-01

    The nonlinear evolution of the single-mode ablative Rayleigh-Taylor instability is studied in three dimensions. As the mode wavelength approaches the cutoff of the linear spectrum (short-wavelength modes), it is found that the three-dimensional (3D) terminal bubble velocity greatly exceeds both the two-dimensional (2D) value and the classical 3D bubble velocity. Unlike in 2D, the 3D short-wavelength bubble velocity does not saturate. The growing 3D bubble acceleration is driven by the unbounded accumulation of vorticity inside the bubble. The vorticity is transferred by mass ablation from the Rayleigh-Taylor spikes to the ablated plasma filling the bubble volume

  10. Kerr-lens mode-locked Ti:Sapphire laser pumped by a single laser diode

    Science.gov (United States)

    Kopylov, D. A.; Esaulkov, M. N.; Kuritsyn, I. I.; Mavritskiy, A. O.; Perminov, B. E.; Konyashchenko, A. V.; Murzina, T. V.; Maydykovskiy, A. I.

    2018-04-01

    The performance of a Ti:sapphire laser pumped by a single 461 nm laser diode is presented for both the continuous-wave and the mode-locked regimes of operation. We introduce a simple astigmatism correction scheme for the laser diode beam consisting of two cylindrical lenses affecting the pump beam along the fast axis of the laser diode, which provides the mode-matching between the nearly square-shaped pump beam and the cavity mode. The resulting efficiency of the suggested Ti:Sapphire oscillator pumped by such a laser diode is analyzed for the Ti:sapphire crystals of 3 mm, 5 mm and 10 mm in length. We demonstrate that such a system provides the generation of ultrashort pulses up to 15 fs in duration with the repetition rate of 87 MHz, the average power being 170 mW.

  11. Coherent properties of single quantum dot transitions and single photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Ester, Patrick

    2008-04-23

    of the first laser pulse. The relative phase of the QDs exciton can be controlled externally via the bias voltage. This effect is the basis for the observation of RAMSEY-fringes, which are presented in this work. The coherent manipulation of the p-shell is the basis for a novel excitation scheme for single photon emission. In this work it is shown that the first excited state can be coherently manipulated, similar to the ground state. (orig.)

  12. Coherent properties of single quantum dot transitions and single photon emission

    International Nuclear Information System (INIS)

    Ester, Patrick

    2008-01-01

    of the first laser pulse. The relative phase of the QDs exciton can be controlled externally via the bias voltage. This effect is the basis for the observation of RAMSEY-fringes, which are presented in this work. The coherent manipulation of the p-shell is the basis for a novel excitation scheme for single photon emission. In this work it is shown that the first excited state can be coherently manipulated, similar to the ground state. (orig.)

  13. Orthopedic applications of single photon emission computed Tomographic bone scanning

    International Nuclear Information System (INIS)

    Collier, B.D.

    1987-01-01

    When compared with planar bone scanning, single photon emission computed tomography (SPECT) has technical advantages of potential diagnostic significance. Planar imaging often superimposes substantial underlying or overlying activity on the bony structure of medical interest. SPECT, however, can be used to remove such unwanted activity. For example, in the hip the acetabulum extends downwards behind the femoral head. Therefore when using planar bone scanning techniques, the photon-deficient defect typical of avascular necrosis (AVN) of the femoral had may be obscured by activity originating in the underlying acetabulum. By using SPECT, underlying and overlying distributions of activity can be separated into sequential tomographic planes. For this reason SPECT facilitates the detection of AVN of the femoral head. When referring a patient without a history of malignancy for bone scanning, the orthopaedic surgeon usually has a specific clinical question involving a limited portion of the skeleton. Orthopaedic surgeons at their institution commonly use bone scanning to clarify the cause of back, hip or knee pain; to determine with a physiological test the significance of radiographic findings; and to establish the extent of disease at symptomatic skeletal sites such as the three compartments of the knee. In instances such as these, when clinical concern is limited to a specific anatomical region, a bone scan procedure that includes SPECT imaging of only a portion of the skeleton is appropriate. To date, SPECT of the skeletal system has most frequently been used to evaluate patients with pain the larger joints and bony structures such as the lumbar spine, hips, knees, or temporomandibular joints (TMJ)

  14. 11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene.

    Science.gov (United States)

    Okhrimchuk, Andrey G; Obraztsov, Petr A

    2015-06-08

    We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires-Tournois interferometer.

  15. Quantum discord dynamics of two qubits in single-mode cavities

    International Nuclear Information System (INIS)

    Wang Chen; Chen Qing-Hu

    2013-01-01

    The dynamics of quantum discord for two identical qubits in two independent single-mode cavities and a common single-mode cavity are discussed. For the initial Bell state with correlated spins, while the entanglement sudden death can occur, the quantum discord vanishes only at discrete moments in the independent cavities and never vanishes in the common cavity. Interestingly, quantum discord and entanglement show opposite behavior in the common cavity, unlike in the independent cavities. For the initial Bell state with anti-correlated spins, quantum discord and entanglement behave in the same way for both independent cavities and a common cavity. It is found that the detunings always stabilize the quantum discord. (general)

  16. High Energy, Single-Mode, All-Solid-State and Tunable UV Laser Transmitter

    Science.gov (United States)

    Prasad, Narasimha S.; Singh, Upendra N.; Hovis, FLoyd

    2007-01-01

    A high energy, single mode, all solid-state Nd:YAG laser primarily for pumping an UV converter is developed. Greater than 1 J/pulse at 50 HZ PRF and pulse widths around 22 ns have been demonstrated. Higher energy, greater efficiency may be possible. Refinements are known and practical to implement. Technology Demonstration of a highly efficient, high-pulse-energy, single mode UV wavelength generation using flash lamp pumped laser has been achieved. Greater than 90% pump depletion is observed. 190 mJ extra-cavity SFG; IR to UV efficiency > 21% (> 27% for 1 mJ seed). 160 mJ intra-cavity SFG; IR to UV efficiency up to 24% Fluence laser is being refined to match or exceed the above UV converter results. Currently the Nd:YAG pump laser development is a technology demonstration. System can be engineered for compact packaging.

  17. Optical field-strength polarization of two-mode single-photon states

    Energy Technology Data Exchange (ETDEWEB)

    Linares, J; Nistal, M C; Barral, D; Moreno, V, E-mail: suso.linares.beiras@usc.e [Optics Area, Department of Applied Physics, Faculty of Physics and School of Optics and Optometry, University of Santiago de Compostela, Campus Universitario Sur s/n, 15782-Santiago de Compostela, Galicia (Spain)

    2010-09-15

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

  18. Optical field-strength polarization of two-mode single-photon states

    International Nuclear Information System (INIS)

    Linares, J; Nistal, M C; Barral, D; Moreno, V

    2010-01-01

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

  19. Bend-insensitive single-mode photonic crystal fiber with ultralarge effective area for dual applications

    Science.gov (United States)

    Islam, Md. Asiful; Alam, M. Shah

    2013-05-01

    A novel photonic crystal fiber (PCF) having circular arrangement of cladding air holes has been designed and numerically optimized to obtain a bend insensitive single mode fiber with large mode area for both wavelength division multiplexing (WDM) communication and fiber-to-the-home (FTTH) application. The bending loss of the proposed bent PCF lies in the range of 10-3 to 10-4 dB/turn or lower over 1300 to 1700 nm, and 2 × 10-4 dB/turn at the wavelength of 1550 nm for a 30-mm bend radius with a higher order mode (HOM) cut-off frequency below 1200 nm for WDM application. When the whole structure of the PCF is scaled down, a bending loss of 6.78×10-4 dB/turn at 1550 nm for a 4-mm bend radius is obtained, and the loss remains in the order of 10-4 dB/turn over the same range of wavelength with an HOM cut-off frequency below 700 nm, and makes the fiber useful for FTTH applications. Furthermore, this structure is also optimized to show a splice loss near zero for fusion-splicing to a conventional single-mode fiber (SMF).

  20. BEND-INDUCED LOSSES IN A SINGLE-MODE MICROSTRUCTURED FIBER WITH A LARGE CORE

    Directory of Open Access Journals (Sweden)

    Y. A. Gatchin

    2015-03-01

    Full Text Available A study of bend-induced losses in a silica-based single-mode microstructured fiber with a core diameter ranging from 20 to 35 microns and increased relative air content in the holey cladding has been conducted. With the use of the equivalent step-index profile method in approximation of waveguide parameters of microstructured fiber (normalized frequency and normalized transverse attenuation constant the effect of bending on the spectral position of the fundamentalmode short-wavelength leakage boundary has been analyzed. Upon measurement of spectral characteristics of attenuation in the considered fibers good accordance of numerical and experimental data has been found out. It is shown that increase of the air content in the holey cladding leads to expansion of the mentioned boundary to lower wavelengths for the value from 150 to 800 nm depending on the core size and bending conditions. A single-transverse-mode propagation is achieved on fiber length of 5-10 meters due to a substantial difference in losses of fundamental and higher-order guided modes attained by bending. Optical losses in all studied samples are less than 10 dB/km at the wavelength λ = 1550 nm. The results of the study can be applied in the design of high-power laser systems having such basic requirements as a relatively large mode spot and high beam quality.

  1. Single longitudinal mode operation of a solid-state dye laser oscillator

    CERN Document Server

    Lim, G; Kim, H S; Cha, B H; Lee, J M

    2000-01-01

    We have operated a single longitudinal mode of a solid-state dye laser oscillator in a Littman configuration. The host material of the solid-state gain medium was rhodamine dye-doped poly (methyl methacrylate). The pumping source was the second harmonic of a Nd:YAG laser with a repetition rate of 10 Hz. The measured linewidth of the laser output was about 1.5 GHz.

  2. Instant recording of the duration of a single mode-locked Nd:YAG laser pulse

    International Nuclear Information System (INIS)

    Lompre, L.A.; Mainfray, G.; Thebault, J.

    1975-01-01

    An electro-optic streak camera incorporating a storage memory video system has been developed and used to instantly visualize and record the shape of a 1.06-μ-wavelength pulse generated by a mode-locked Nd:YAG laser. The duration of a single laser pulse (approximately 30 psec) has been directly measured with and without laser amplification. (U.S.)

  3. Combined effect of viscosity and vorticity on single mode Rayleigh-Taylor instability bubble growth

    International Nuclear Information System (INIS)

    Banerjee, Rahul; Mandal, Labakanta; Roy, S.; Khan, M.; Gupta, M. R.

    2011-01-01

    The combined effect of viscosity and vorticity on the growth rate of the bubble associated with single mode Rayleigh-Taylor instability is investigated. It is shown that the effect of viscosity on the motion of the lighter fluid associated with vorticity accumulated inside the bubble due to mass ablation may be such as to reduce the net viscous drag on the bubble exerted by the upper heavier fluid as the former rises through it.

  4. Cavity Formation Modeling of Fiber Fuse in Single-Mode Optical Fibers

    Directory of Open Access Journals (Sweden)

    Yoshito Shuto

    2017-01-01

    Full Text Available The evolution of a fiber-fuse phenomenon in a single-mode optical fiber was studied theoretically. To clarify both the silica-glass densification and cavity formation, which have been observed in fiber fuse propagation, we investigated a nonlinear oscillation model using the Van Der Pol equation. This model was able to phenomenologically explain both the densification of the core material and the formation of periodic cavities in the core layer as a result of a relaxation oscillation.

  5. Single Mode Optical Fiber based Refractive Index Sensor using Etched Cladding

    OpenAIRE

    Kumar, Ajay; Gupta, Geeta; Mallik, Arun; Bhatnagar, Anuj

    2011-01-01

    The use of optical fiber for sensor applications is a topic of current interest. We report the fabrication of etched single mode optical fiber based refractive index sensor. Experiments are performed to determine the etch rate of fiber in buffered hydrofluoric acid, which can be high or low depending upon the temperature at which etching is carried out. Controlled wet etching of fiber cladding is performed using these measurements and etched fiber region is tested for refractive index sensing...

  6. Single-mode waveguides with SU-8 polymer core and cladding for MOEMS applications

    OpenAIRE

    Nordström, Maria; Zauner, Dan; Boisen, Anja; Hübner, Jörg

    2007-01-01

    Fabrication and optical characterization of singlemode polymeric embedded waveguides are performed. A specific material combination (SU-8 2005 as core and the modified SU-8 mr-L 6050XP as cladding) is chosen in order to obtain a small refractive index difference for single-mode propagation combined with the conventional fabrication method UV lithography to facilitate the integration of different types of optical detection methods on lab-on-a-chip systems. We analyze the behavior of the refrac...

  7. PF-KO system for single bunch mode operation of a storage ring

    International Nuclear Information System (INIS)

    Ohgaki, H.; Sugiyama, S.; Mikado, T.; Chiwaki, M.; Yamada, K.; Suzuki, R.; Sei, N.; Noguchi, T.; Yamazaki, T.

    1994-01-01

    A new RF-KO (RF knockout) system for the single bunch mode operation of a storage ring has been developed. The knockout signal is modulated by the sum signal of the RF acceleration frequency of the storage ring and a bunch selection signal. We do not need any special device or a timing unit with this method. We obtain a high purity of bunch structure in a short knock out time. The single bunch impurity of 0.2% has been achieved. (author)

  8. Design and experiments of a linear piezoelectric motor driven by a single mode.

    Science.gov (United States)

    Liu, Zhen; Yao, Zhiyuan; Li, Xiang; Fu, Qianwei

    2016-11-01

    In this contribution, we propose a novel linear piezoelectric motor with a compact stator that is driven by a single mode. The linear piezoelectric motor can realize bidirectional motion by changing the vibration modes of the stator. Finite element analysis is performed to determine the required vibration mode of the stator and obtain the optimal stator structure and dimensions. Furthermore, the trajectories of the driving foot are analyzed with and without consideration of the mechanical contact with the slider. It is shown that the trajectory of the driving foot is an oblique line when disregarding the contact, and the trajectory becomes an oblique ellipse while taking into account the contact. Finally, a prototype of the motor is fabricated based on the results of finite element analysis. The optimization results show that the motor reaches its maximum thrust force of 4.0 kg, maximum thrust-weight ratio of 33.3, maximum unloaded velocity of 385 mm/s under the excitation of Mode-B, and maximum unloaded velocity of 315 mm/s under the excitation of Mode-L.

  9. Few-mode vertical-cavity surface-emitting laser: Optional emission of transverse modes with different polarizations

    Science.gov (United States)

    Zhong, Chuyu; Zhang, Xing; Hofmann, Werner; Yu, Lijuan; Liu, Jianguo; Ning, Yongqiang; Wang, Lijun

    2018-05-01

    Few-mode vertical-cavity surface-emitting lasers that can be controlled to emit certain modes and polarization states simply by changing the biased contacts are proposed and fabricated. By directly etching trenches in the p-doped distributed Bragg reflector, the upper mesa is separated into several submesas above the oxide layer. Individual contacts are then deposited. Each contact is used to control certain transverse modes with different polarization directions emitted from the corresponding submesa. These new devices can be seen as a prototype of compact laser sources in mode division multiplexing communications systems.

  10. Single frequency Nd:YLF and Nd:YVO4 laser in the red emission

    International Nuclear Information System (INIS)

    Camargo, Fabiola de Almeida

    2010-01-01

    All solid-state continuous-wave (cw) narrow emission linewidth and tunable red lasers are convenient alternative sources to bulky and expensive dye-lasers for high precision laser spectroscopy. Single-frequency operation of diode-pumped Nd:YLiF 4 and Nd:YVO 4 cw ring lasers were investigated in the 1.32 - 1.34μm range, together with their intracavity second-harmonic generation (SHG) to the red spectral range (0.65 - 0.67μm) using either BiB 3 O 6 (BiBO) or periodically-poled KTiOPO 4 (ppKTP) crystals. We report on such a single-end diode-pumped Nd:YVO 4 unidirectional red ring laser containing a type-I cut BiBO nonlinear crystal, yielding a record of 680 mW of single-longitudinal mode (SLM) red output power at 671.1nm without any intra-cavity etalon. For smooth SLM wavelength tuning over the full gain bandwidth (∼4 nm), a partially-coated (R = 40%) 100μm-thin etalon was found necessary, reducing the maximum SLM power (at 671.15 nm) to 380 mW. At 1342.5nm and with a T = 2% transmission output coupler, the laser provided an optimal 1.5W of single-frequency power. We demonstrate also optimal intracavity SHG of a Nd:YLF ring laser in the π- polarization (λ = 1321.5nm) using a ppKTP. The laser yielded 1.4 W of single frequency red power at 660.5 nm, as much as the maximum fundamental power that can be extracted from the resonator using an optimal output coupler. With a partially coated (R = 25%) thin etalon, the laser was tunable over Δλ∼ 1.6nm. (author)

  11. Single-nanoparticle detection with slot-mode photonic crystal cavities

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cheng; Kita, Shota; Lončar, Marko, E-mail: loncar@seas.harvard.edu [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Quan, Qimin [Rowland Institute at Harvard University, Cambridge, Massachusetts 02142 (United States); Li, Yihang [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China)

    2015-06-29

    Optical cavities that are capable for detecting single nanoparticles could lead to great progress in early stage disease diagnostics and the study of biological interactions on the single-molecule level. In particular, photonic crystal (PhC) cavities are excellent platforms for label-free single-nanoparticle detection, owing to their high quality (Q) factors and wavelength-scale modal volumes. Here, we demonstrate the design and fabrication of a high-Q (>10{sup 4}) slot-mode PhC nanobeam cavity, which is able to strongly confine light in the slotted regions. The enhanced light-matter interaction results in an order of magnitude improvement in both refractive index sensitivity (439 nm/RIU) and single-nanoparticle sensitivity compared with conventional dielectric-mode PhC cavities. Detection of single polystyrene nanoparticles with radii of 20 nm and 30 nm is demonstrated in aqueous environments (D{sub 2}O), without additional laser and temperature stabilization techniques.

  12. Experimental demonstration of a simple displacement sensor based on a bent single-mode–multimode–single-mode fiber structure

    International Nuclear Information System (INIS)

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

    2011-01-01

    A simple displacement sensor based on a bent single-mode–multimode–single-mode (SMS) fiber structure is proposed and experimentally investigated. The sensor offers a wider displacement range, not limited by the risk of fiber breakage, as well as a three-fold increase in displacement sensitivity by comparison with a straight SMS structure sensor. This sensor can be interrogated by either an optical spectral analyzer (OSA) or a ratiometric interrogation system: (1) if interrogated by an OSA assuming a resolution of 1 pm, it has a sensitivity of 28.2 nm for a displacement measurement range from 0 to 280 µm; (2) if interrogated by a ratiometric interrogation system, it has worst and best case resolutions of 556 and 38 nm, respectively, for a displacement measurement range from 0 to 520 µm

  13. Three-Input Single-Output Voltage-Mode Multifunction Filter with Electronic Controllability Based on Single Commercially Available IC

    Directory of Open Access Journals (Sweden)

    Supachai Klungtong

    2017-01-01

    Full Text Available This paper presents a second-order voltage-mode filter with three inputs and single-output voltage using single commercially available IC, one resistor, and two capacitors. The used commercially available IC, called LT1228, is manufactured by Linear Technology Corporation. The proposed filter is based on parallel RLC circuit. The filter provides five output filter responses, namely, band-pass (BP, band-reject (BR, low-pass (LP, high-pass (HP, and all-pass (AP functions. The selection of each filter response can be done without the requirement of active and passive component matching condition. Furthermore, the natural frequency and quality factor are electronically controlled. Besides, the nonideal case is also investigated. The output voltage node exhibits low impedance. The experimental results can validate the theoretical analyses.

  14. Electrically-pumped, broad-area, single-mode photonic crystal lasers.

    Science.gov (United States)

    Zhu, Lin; Chak, Philip; Poon, Joyce K S; DeRose, Guy A; Yariv, Amnon; Scherer, Axel

    2007-05-14

    Planar broad-area single-mode lasers, with modal widths of the order of tens of microns, are technologically important for high-power applications and improved coupling efficiency into optical fibers. They may also find new areas of applications in on-chip integration with devices that are of similar size scales, such as for spectroscopy in microfluidic chambers or optical signal processing with micro-electromechanical systems. An outstanding challenge is that broad-area lasers often require external means of control, such as injection-locking or a frequency/spatial filter to obtain single-mode operation. In this paper, we propose and demonstrate effective index-guided, large-area, edge-emitting photonic crystal lasers driven by pulsed electrical current injection at the optical telecommunication wavelength of 1550 nm. By suitable design of the photonic crystal lattice, our lasers operate in a single mode with a 1/e(2) modal width of 25 microm and a length of 600 microm.

  15. Single-mode electrically pumped GaSb-based VCSELs emitting continuous-wave at 2.4 and 2.6 μm

    International Nuclear Information System (INIS)

    Bachmann, Alexander; Arafin, Shamsul; Kashani-Shirazi, Kaveh

    2009-01-01

    Vertical-cavity surface-emitting lasers (VCSELs) are perfect light sources for spectroscopic applications, where properties such as continuous-wave (cw) operation, single-mode emission, high lifetime and often low power consumption are crucial. For applications such as tunable diode laser absorption spectroscopy (TDLAS), there is a growing interest in laser devices emitting in the near- to mid-infrared wavelength range, where many environmentally and technologically important gases show strong absorption lines. The (AlGaIn)(AsSb) material system based on GaSb is the material of choice for covering the 2.0-3.3 μm range. In this paper, we report on electrically pumped single-mode VCSELs with emission wavelengths of 2.4 and 2.6 μm, operating cw at room temperature and beyond. By (electro-) thermal tuning, the emission wavelength can be tuned mode-hop free over a range of several nanometers. In addition, low threshold currents of several milliamperes promise mobile application. In the devices, a structured buried tunnel junction with subsequent overgrowth has been used in order to achieve efficient current confinement, reduced optical losses and increased electrical conductivity. Furthermore, strong optical confinement is introduced in the lasers due to laterally differing cavity lengths.

  16. Mode-converted electron Bernstein wave emission research on CDX-U and NSTX

    International Nuclear Information System (INIS)

    Taylor, G.; Efthimion, P.C; Jones, B.; Munsat, T.; Hosea, J.C; Kaita, R.; Majeski, R.; Spaleta, J.; Wilson, J.R.; Wilgen, J.B.; Bell, G.L.; Rasmussen, D.A.; Ram, A.K.; Bers, A.; Harvey, R.W.; Smirnov, A.P.

    2003-01-01

    Electron Bernstein waves (EBWs) may enable electron temperature profile measurements and local electron heating and current drive in high β overdense (ω pe /ω ce >>1) plasmas. Significant results are presented from the measurement of X-mode radiation, converted from EBWs observed normal to the magnetic field on the mid-plane of overdense plasmas in CDX-U and NSTX. A radially scannable, in-vessel, quad-ridged antenna and Langmuir probe array on CDX-U studied EBW to X-mode conversion. A local limiter optimized the conversion efficiency by modifying the density scale length at the mode conversion layer. The fundamental EBW conversion efficiency increased, by an order of magnitude, to ∼100% when the local limiter and antenna were inserted near the conversion layer. This technique can be extended to large, high temperature devices. Another significant observation was that the EBW emission source was localized near the electron cyclotron resonance. As a result, mode-converted EBW radiometry has measured radial transport in CDX-U. In addition, a threefold increase in conversion efficiency was observed at the L to H transition in NSTX. Measured conversion efficiency agreed well with theoretical predictions. EBW ray tracing and bounce-averaged Fokker-Planck codes are being used to model EBW heating and current drive scenarios for NSTX equilibria with β up to 40%. So far, results show that it is possible to drive localized currents on the high field side of the magnetic axis in NSTX at β ∼ 12% with current drive efficiency which compares favorably with ECCD. (authors)

  17. Comparison of emissions from on-road sources using a mobile laboratory under various driving and operational sampling modes

    Directory of Open Access Journals (Sweden)

    M. Zavala

    2009-01-01

    Full Text Available Mobile sources produce a significant fraction of the total anthropogenic emissions burden in large cities and have harmful effects on air quality at multiple spatial scales. Mobile emissions are intrinsically difficult to estimate due to the large number of parameters affecting the emissions variability within and across vehicles types. The MCMA-2003 Campaign in Mexico City has showed the utility of using a mobile laboratory to sample and characterize specific classes of motor vehicles to better quantify their emissions characteristics as a function of their driving cycles. The technique clearly identifies "high emitter" vehicles via individual exhaust plumes, and also provides fleet average emission rates. We have applied this technique to Mexicali during the Border Ozone Reduction and Air Quality Improvement Program (BORAQIP for the Mexicali-Imperial Valley in 2005. We analyze the variability of measured emission ratios for emitted NOx, CO, specific VOCs, NH3, and some primary fine particle components and properties by deploying a mobile laboratory in roadside stationary sampling, chase and fleet average operational sampling modes. The measurements reflect various driving modes characteristic of the urban fleets. The observed variability for all measured gases and particle emission ratios is greater for the chase and roadside stationary sampling than for fleet average measurements. The fleet average sampling mode captured the effects of traffic conditions on the measured on-road emission ratios, allowing the use of fuel-based emission ratios to assess the validity of traditional "bottom-up" emissions inventories. Using the measured on-road emission ratios, we estimate CO and NOx mobile emissions of 175±62 and 10.4±1.3 metric tons/day, respectively, for the gasoline vehicle fleet in Mexicali. Comparisons with similar on-road emissions data from Mexico City indicated that fleet average NO emission ratios were

  18. MRPC prototypes for NeuLAND tested using the single electron mode of ELBE/Dresden

    Energy Technology Data Exchange (ETDEWEB)

    Yakorev, Dmitry; Bemmerer, Daniel; Elekes, Zoltan; Kempe, Mathias; Stach, Daniel; Wagner, Andreas [Forschungszentrum Dresden-Rossendorf (FZD), Dresden (Germany); Aumann, Tom; Boretzky, Konstanze; Caesar, Christoph; Ciobanu, Mircea; Hehner, Joerg; Heil, Michael; Nusair, Omar; Reifarth, Rene; Simon, Haik [GSI, Darmstadt (Germany); Elvers, Michael; Maroussov, Vassili; Zilges, Andreas [Universitaet Koeln (Germany); Zuber, Kai [TU Dresden (Germany)

    2010-07-01

    The NeuLAND detector at the R{sup 3}B experiment at the future FAIR facility in Darmstadt aims to detect fast neutrons (0.2-1.0 GeV) with high time and spatial resolutions ({sigma}{sub t}<100 ps, {sigma}{sub x,y,z}<1 cm). Prototypes for the NeuLAND detector have been built at FZD and GSI and then studied using the 32 MeV pulsed electron beam at the superconducting electron accelerator ELBE in Dresden, Germany. Owing to the new, single-electron per bunch mode of operation, a rapid validation of the design criteria ({>=}90% efficiency for minimum ionizing particles, {sigma} {<=} 100 ps time resolution) was possible. Tested properties of the prototypes include glass thickness, spacing of the central anode, and a comparison of single-ended and differential readout. Tested frontend electronics schemes include FOPI (single-ended), PADI-based (both single-ended and differential mode tested), and ALICE (differential).

  19. Multifunction Voltage-Mode Filter Using Single Voltage Differencing Differential Difference Amplifier

    Directory of Open Access Journals (Sweden)

    Chaichana Amornchai

    2017-01-01

    Full Text Available In this paper, a voltage mode multifunction filter based on single voltage differencing differential difference amplifier (VDDDA is presented. The proposed filter with three input voltages and single output voltage is constructed with single VDDDA, two capacitors and two resistors. Its quality factor can be adjusted without affecting natural frequency. Also, the natural frequency can be electronically tuned via adjusting of bias current. The filter can offer five output responses, high-pas (HP, band-pass (BP, band-reject (BR, low-pass (LP and all-ass (AP functions in the same circuit topology. The output response can be selected by choosing the suitable input voltage without the component matching condition and the requirement of additional double gain voltage amplifier. PSpice simulation results to confirm an operation of the proposed filter correspond to the theory.

  20. Design of single-longitudinal-mode laser oscillator for edge Thomson scattering system in ITER

    International Nuclear Information System (INIS)

    Hatae, Takaki; Kusama, Yoshinori; Kubomura, Hiroyuki; Matsuoka, Shin-ichi

    2006-06-01

    A high output energy (5J) and high repetition rate (100 Hz) laser system is required for the edge Thomson scattering system in ITER. A YAG laser (Nd:YAG laser) is a first candidate for the laser system satisfying the requirements. It is important to develop a high beam quality and single longitudinal mode (SLM) laser oscillator in order to realize this high power laser system. In this design work, following activities relating to the SLM laser oscillator have been carried out: design of the laser head and the resonator, estimation of the output power for the SLM laser oscillator, consideration of the feedback control scheme and consideration of interface for amplification system to achieve required performance (5J, 100 Hz). It is expected that the designed laser diode (LD) pumped SLM laser oscillator realizes: 100 Hz of repetition rate, 10 mJ of output energy, 10 ns of pulse width, single longitudinal mode, TEM 00 of transversal mode, divergence less than 4 times of the diffraction limit, energy stability within 5%. (author)

  1. New VCSEL technology with scalability for single mode operation and densely integrated arrays

    Science.gov (United States)

    Zhao, Guowei; Demir, Abdullah; Freisem, Sabine; Zhang, Yu; Liu, Xiaohang; Deppe, Dennis G.

    2011-06-01

    Data are presented demonstrating a new lithographic vertical-cavity surface-emitting laser (VCSEL) technology, which produces simultaneous mode- and current-confinement only by lithography and epitaxial crystal growth. The devices are grown by solid source molecular beam epitaxy, and have lithographically defined sizes that vary from 3 μm to 20 μm. The lithographic process allows the devices to have high uniformity throughout the wafer and scalability to very small size. The 3 μm device shows a threshold current of 310 μA, the slope efficiency of 0.81 W/A, and the maximum output power of more than 5 mW. The 3 μm device also shows single-mode single-polarization operation without the use of surface grating, and has over 25 dB side-mode-suppression-ratio up to 1 mW of output power. The devices have low thermal resistance due to the elimination of oxide aperture. High reliability is achieved by removal of internal strain caused by the oxide, stress test shows no degradation for the 3 μm device operating at very high injection current level of 142 kA/cm2 for 1000 hours, while at this dive level commercial VCSELs fail rapidly. The lithographic VCSEL technology can lead to manufacture of reliable small size laser diode, which will have application in large area 2-D arrays and low power sensors.

  2. A novel L-shaped linear ultrasonic motor operating in a single resonance mode

    Science.gov (United States)

    Zhang, Bailiang; Yao, Zhiyuan; Liu, Zhen; Li, Xiaoniu

    2018-01-01

    In this study, a large thrust linear ultrasonic motor using an L-shaped stator is described. The stator is constructed by two mutually perpendicular rectangular plate vibrators, one of which is mounted in parallel with the slider to make the motor structure to be more compact. The symmetric and antisymmetric modes of the stator based on the first order bending vibration of two vibrators are adopted, in which each resonance mode is assigned to drive the slider in one direction. The placement of piezoelectric ceramics in a stator could be determined by finite element analysis, and the influence of slots in the head block on the vibration amplitudes of driving foot was studied as well. Three types of prototypes (non-slotted, dual-slot, and single-slot) were fabricated and experimentally investigated. Experimental results demonstrated that the prototype with one slot exhibited the best mechanical output performance. The maximum loads under the excitation of symmetric mode and antisymmetric mode were 65 and 90 N, respectively.

  3. Impact of quantum–classical correspondence on entanglement enhancement by single-mode squeezing

    International Nuclear Information System (INIS)

    Joseph, Sijo K.; Chew, Lock Yue; Sanjuán, Miguel A.F.

    2014-01-01

    Quantum entanglement between two field modes can be achieved through the collective squeezing of the two respective modes. If single-mode squeezing is performed prior to such a two-mode squeezing, an enhancement of entanglement production can happen. Interestingly, the occurrence of this enhancement can be implicitly linked to the local classical dynamical behavior via the paradigm of quantum–classical correspondence. In particular, the entanglement generated through quantum chaos is found to be hardly enhanced by prior squeezing, since it is bounded by the saturation value of the maximally entangled Schmidt state with fixed energy. These results illustrate that entanglement enhancement via initial squeezing can serve as a useful indicator of quantum chaotic behaviour. - Highlights: • Continuous-variable entanglement is explored in the Pullen–Edmonds Hamiltonian. • The local phase-space structure and the entanglement enhancement are related. • Entanglement enhancement via squeezing is smaller for the chaotic orbit. • Entanglement enhancement via squeezing is higher for the regular orbit. • The magnitude of the entanglement enhancement serves as a quantum-chaos indicator

  4. Single mode operation in a pulsed Ti:sapphire laser oscillator with a grazing-incidence four-mirror cavity

    CERN Document Server

    Ko, D K; Binks, D J; Gloster, L A W; King, T A

    1998-01-01

    We demonstrate stable single mode operation in a pulsed Ti:sapphire laser oscillator with a novel grazing-incidence four-mirror coupled cavity. This cavity consists of a grating, a gain medium, and four mirrors and, therefore, has a four-arm interferometer configuration. Through the interferometric effect, we could suppress the adjacent modes and obtain stable single mode operation with a bandwidth of < 200 MHz. We also have developed a general analysis of the laser modes and the threshold conditions for configuration and the experimental results agree well with the theoretical predictions.

  5. Explosive-Emission Plasma Dynamics in Ion Diode in Double-Pulse Mode

    International Nuclear Information System (INIS)

    Pushkarev, Alexander I.; Isakova, Yulia I.

    2011-01-01

    The results of an experimental investigation of explosive-emission plasma dynamics in an ion diode with self-magnetic insulation are presented. The investigations were accomplished at the TEMP-4M accelerator set in a mode of double pulse formation. Plasma behaviour in the anode-cathode gap was analyzed according to both the current-voltage characteristics of the diode (time resolution of 0.5 ns) and thermal imprints on a target (spatial resolution of 0.8 mm). It was shown that when plasma formation at the potential electrode was complete, and up until the second (positive) pulse, the explosive-emission plasma expanded across the anode-cathode gap with a speed of 1.3±0.2 cm/μs. After the voltage polarity at the potential electrode was reversed (second pulse), the plasma erosion in the anode-cathode gap (similar to the effect of a plasma opening switch) occurred. During the generation of an ion beam the size of the anode-cathode gap spacing was determined by the thickness of the plasma layer on the potential electrode and the layer thickness of the electrons drifting along the grounded electrode. (15th asian conference on electrical discharge)

  6. Report on first masing and single mode locking in a prebunched beam FEM oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M.; Eichenbaum, A.; Kleinman, H. [Tel-Aviv Univ., Ramat-Aviv (Israel)] [and others

    1995-12-31

    Radiation characteristics of a table-top free electron maser (FEM) are described in this paper. The FEM employs a prebunched electron beam and is operated as an oscillator in the low-gain collective (Raman) regime. Using electron beam prebunching single mode locking at any one of the possible oscillation modes was obtained. The electron beam is prebunched by a microwave tube section before it is injected into the wiggler. By tuning the electron beam bunching frequency, the FEM oscillation frequency can be locked to any eigen frequency of the resonant waveguide cavity which is within the frequency band of net gain of the FEM. The oscillation build up process is sped up, when the FEM operates with a prebunched electron beam, and the build-up time of radiation is shortened significantly. First measurements of masing with and without prebunching and characterization of the emitted radiation are reported.

  7. Microwave measurements of energy lost to longitudinal modes by single electron bunches traversing periodic structures

    International Nuclear Information System (INIS)

    Wang, J.W.; Loew, G.A.; Weaver, J.N.; Wilson, P.B.

    1981-10-01

    In the design of future linear colliders, it will be important to minimize the loss of beam energy due to the excitation of higher-order modes in the accelerator structure by single bunches of electrons or positrons. This loss is not only detrimental in itself but also gives rise to energy spectrum widening and transverse emittance growth. Microwave measurements made on disk-loaded and alternating-spoke structures to determine the loss to the longitudinal modes are described. In these measurements the Gaussian bunch is simulated by a current pulse of the same shape transmitted through the structure on an axial center conductor. Results to date are presented for the total longitudinal loss parameter per period K in volts per picocoulomb

  8. Diffusion-cooled high-power single-mode waveguide CO2 laser for transmyocardial revascularization

    Science.gov (United States)

    Berishvili, I. I.; Bockeria, L. A.; Egorov, E. N.; Golubev, Vladimir S.; Galushkin, Michail G.; Kheliminsky, A. A.; Panchenko, Vladislav Y.; Roshin, A. P.; Sigaev, I. Y.; Vachromeeva, M. N.; Vasiltsov, Victor V.; Yoshina, V. I.; Zabelin, Alexandre M.; Zelenov, Evgenii V.

    1999-01-01

    The paper presents the results on investigations and development of multichannel waveguide CO2 laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO2 laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.

  9. Evaluation of single photon and Geiger mode Lidar for the 3D Elevation Program

    Science.gov (United States)

    Stoker, Jason M.; Abdullah, Qassim; Nayegandhi, Amar; Winehouse, Jayna

    2016-01-01

    Data acquired by Harris Corporation’s (Melbourne, FL, USA) Geiger-mode IntelliEarth™ sensor and Sigma Space Corporation’s (Lanham-Seabrook, MD, USA) Single Photon HRQLS sensor were evaluated and compared to accepted 3D Elevation Program (3DEP) data and survey ground control to assess the suitability of these new technologies for the 3DEP. While not able to collect data currently to meet USGS lidar base specification, this is partially due to the fact that the specification was written for linear-mode systems specifically. With little effort on part of the manufacturers of the new lidar systems and the USGS Lidar specifications team, data from these systems could soon serve the 3DEP program and its users. Many of the shortcomings noted in this study have been reported to have been corrected or improved upon in the next generation sensors.

  10. Electrically tunable Brillouin fiber laser based on a metal-coated single-mode optical fiber

    Directory of Open Access Journals (Sweden)

    S.M. Popov

    Full Text Available We explore tunability of the Brillouin fiber laser employing Joule heating. For this purpose, 10-m-length of a metal-coated single-mode optical cavity fiber has been directly included into an electrical circuit, like a conductor wire. With the current up to ∼3.5 A the laser tuning is demonstrated over a spectrum range of ∼400 MHz. The observed laser line broadening up to ∼2 MHz is explained by frequency drift and mode-hoping in the laser caused by thermal noise. Keywords: Brillouin fiber laser, Metal-coated optical fiber, Laser tuning, Fiber sensors

  11. 2-kW single-mode fiber laser employing bidirectional-pump scheme

    Science.gov (United States)

    Zhang, Fan; Zheng, Wenyou; Shi, Pengyang; Zhang, Xinhai

    2018-01-01

    2kW single-mode fiber laser with two cascade home-made cladding light strippers (CLSs) by employing bidirectionalpump scheme has been demonstrated. 2.009 kW signal power is obtained when pump power is 2.63 kW and the slope efficiency is 76.6%. Raman Stokes light is less than -47 dB at 2.009 kW even with a 10-m delivery fiber with core/inner cladding diameter of 20/400um. The beam quality M2<=1.2 and the spectral FWHM bandwidth is 4.34nm. There is no transverse mode instability and the output power stability of +/-0.14% is achieved by special thermal management for a more uniform temperature distribution on the Yb-doped gain fiber.

  12. Harmonics Suppression for Single-Phase Grid-Connected Photovoltaic Systems in Different Operation Modes

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede

    2013-01-01

    -connected PV inverters may be severely affected in different operation modes. In this paper, a detailed analysis is conducted to reveal the relationship between the harmonics level with the power factor and the current level in the PV systems. A current control solution which employs an Internal Model...... Principle (IMP) is proposed to suppress the harmonic currents injected into the grid. Experiments are carried out to verify the analysis and the performance of the proposed control method. It is demonstrated that the proposed method presents an effective solution to harmonics suppression for single......-phase grid-connected PV systems in different operation modes. Especially, it can remove higher order harmonics effectively leading to a better power quality compared to the Proportional plus Multi-Resonant Controller, and it has less computational burden....

  13. Tunneling-Electron-Induced Light Emission from Single Gold Nanoclusters.

    Science.gov (United States)

    Yu, Arthur; Li, Shaowei; Czap, Gregory; Ho, W

    2016-09-14

    The coupling of tunneling electrons with the tip-nanocluster-substrate junction plasmon was investigated by monitoring light emission in a scanning tunneling microscope (STM). Gold atoms were evaporated onto the ∼5 Å thick Al2O3 thin film grown on the NiAl (110) surface where they formed nanoclusters 3-7 nm wide. Scanning tunneling spectroscopy (STS) of these nanoclusters revealed quantum-confined electronic states. Spatially resolved photon imaging showed localized emission hot spots. Size dependent study and light emission from nanocluster dimers further support the viewpoint that coupling of tunneling electrons to the junction plasmon is the main radiative mechanism. These results showed the potential of the STM to reveal the electronic and optical properties of nanoscale metallic systems in the confined geometry of the tunnel junction.

  14. Thermal radio emission from the winds of single stars

    International Nuclear Information System (INIS)

    Abbott, D.C.

    1985-01-01

    Observations of thermal emission at radio wavelengths provides a powerful diagnostic of the rate of mass loss and temperature of the winds of early-type stars. Some winds are also strong sources of nonthermal emission. Case studies of known thermal and nonthermal sources provide empirical criteria for classifying the observed radio radiation. Mass loss rates are derived for 37 OB and Wolf-Rayet stars considered definite or probable thermal wind sources by these criteria. The rate of mass loss is strongly linked to stellar luminosity in OB stars and probably linked to stellar mass in Wolf-Rayet stars, with no measurable correlation with any other stellar property. A few late-type giants and supergiants also have detectable thermal emission, which arises from extended, accelerating, partially-ionized chromospheres. (orig.)

  15. Study of the impact of board orientation on radiated emissions due to common-mode currents on attached cables

    DEFF Research Database (Denmark)

    Sørensen, Morten; Hubing, Todd H.; Jensen, Kim

    2016-01-01

    Common-mode current on attached cables is a typical source for radiated emission. Several models have been made for conversion of the intended differential signal to unwanted common-mode current on cables. In this paper we refine a method for identifying the radiation sources arising from a long...... microstrip. This method is used to show that the radiated emission from a PCB with attached cable(s) caused by a long trace depends on whether the trace is facing up or down with different result for voltage and current sources....

  16. Fine structure of the stimulated Raman spectrum in compressed hydrogen. The relaxation-oscillation mode of backscattered Stokes emission

    International Nuclear Information System (INIS)

    Bespalov, V.G.; Efimov, Yu.N.; Staselko, D.I.

    1992-01-01

    This paper studies the emission spectra of backscattered stimulated Raman scattering (SRS) in compressed hydrogen in the relaxation-oscillation mode and the compression SRS mode for the minimum width of the spontaneous scattering spectrum (in the region of the Dicke dip). It is shown that the generation of a train of Stokes-emission subpulses results in the appearance of fine structure in the backscattered SRS spectrum. The influence of the temporal structure of reflected Stokes pulses on this spectrum and on the appearance of fine structure in it is analyzed. The conditions for generating spectrally limited (without phase modulation), extremely coherent Stokes pulses are explained. 18 refs., 3 figs

  17. Differential modal delay measurements in a graded-index multimode fibre waveguide, using a single-mode fibre pro mode selection

    International Nuclear Information System (INIS)

    Sunak, H.R.D.; Soares, S.M.

    1981-01-01

    Differential model delay (DMD) measurements in graded-index multimode optical fibre waveguides, which are very promising for many types of communication system were carried out. These DMD measurements give a direct indication of the deviation of the refractive index profile, from the optimum value, at a given wavelength. For the first time, by using a single-mode fibre, a few guided modes in the graded-index fibre were selected, in two different ways: launching a few modes at the input end or selecting a few modes at the output end. By doing so important features of propagation in the fibre were revealed, especially the intermodal coupling that may exist. The importance of this determination of intermodal coupling or mode mixing, particularly when many fibres are joined together in a link, and the merits of DMD measurements in general and their importance for the production of high bandwidth graded-index fibres are discussed. (Author) [pt

  18. Modeling natural emissions in the Community Multiscale Air Quality (CMAQ) Model-I: building an emissions data base

    Science.gov (United States)

    Smith, S. N.; Mueller, S. F.

    2010-05-01

    A natural emissions inventory for the continental United States and surrounding territories is needed in order to use the US Environmental Protection Agency Community Multiscale Air Quality (CMAQ) Model for simulating natural air quality. The CMAQ air modeling system (including the Sparse Matrix Operator Kernel Emissions (SMOKE) emissions processing system) currently estimates non-methane volatile organic compound (NMVOC) emissions from biogenic sources, nitrogen oxide (NOx) emissions from soils, ammonia from animals, several types of particulate and reactive gas emissions from fires, as well as sea salt emissions. However, there are several emission categories that are not commonly treated by the standard CMAQ Model system. Most notable among these are nitrogen oxide emissions from lightning, reduced sulfur emissions from oceans, geothermal features and other continental sources, windblown dust particulate, and reactive chlorine gas emissions linked with sea salt chloride. A review of past emissions modeling work and existing global emissions data bases provides information and data necessary for preparing a more complete natural emissions data base for CMAQ applications. A model-ready natural emissions data base is developed to complement the anthropogenic emissions inventory used by the VISTAS Regional Planning Organization in its work analyzing regional haze based on the year 2002. This new data base covers a modeling domain that includes the continental United States plus large portions of Canada, Mexico and surrounding oceans. Comparing July 2002 source data reveals that natural emissions account for 16% of total gaseous sulfur (sulfur dioxide, dimethylsulfide and hydrogen sulfide), 44% of total NOx, 80% of reactive carbonaceous gases (NMVOCs and carbon monoxide), 28% of ammonia, 96% of total chlorine (hydrochloric acid, nitryl chloride and sea salt chloride), and 84% of fine particles (i.e., those smaller than 2.5 μm in size) released into the atmosphere

  19. Dynamics of Nonlinear Excitation of the High-Order Mode in a Single-Mode Step-Index Optical Fiber

    Science.gov (United States)

    Burdin, V.; Bourdine, A.

    2018-04-01

    This work is concerned with approximate model of higher-order mode nonlinear excitation in a singlemode silica optical fiber. We present some results of simulation for step-index optical fiber under femtosecond optical pulse launching, which confirm ability of relatively stable higher-order mode excitation in such singlemode optical fiber over sufficiently narrow range of launched optical power variation.

  20. Optical measuring system with an interrogator and a polymer-based single-mode fibre optic sensor system

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates to an optical measuring system comprising a polymer-based single-mode fibre-optic sensor system (102), an optical interrogator (101), and an optical arrangement (103) interconnecting the optical interrogator (101) and the polymer-based single-mode fibre-optic sensor...... system (102). The invention further relates to an optical interrogator adapted to be connected to a polymer-based single-mode fibre-optic sensor system via an optical arrangement. The interrogator comprises a broadband light source arrangement (104) and a spectrum analysing arrangement which receives...

  1. Tunable single photonic defect-mode in cholesteric liquid crystals with laser-induced local modifications of helix

    International Nuclear Information System (INIS)

    Yoshida, Hiroyuki; Lee, Chee Heng; Fujii, Akihiko; Ozaki, Masanori

    2006-01-01

    The authors demonstrate a tunable single photonic defect-mode in a single cholesteric liquid crystal material based on a structural defect introduced by local modification of the helix. An unpolymerized region of cholesteric liquid crystal acting as the defect was left between two polymerized regions via a two-photon excitation laser-lithography process. Upon polymerization, the cholesteric liquid crystal helix elongated and became thermally stable, and a single photonic defect mode was exhibited due to the contrast in the helix pitch at the defect. The defect mode showed tunability upon heating, and a 36 nm redshift was seen over a temperature range of 30 deg. C

  2. Response of two-band systems to a single-mode quantized field

    Science.gov (United States)

    Shi, Z. C.; Shen, H. Z.; Wang, W.; Yi, X. X.

    2016-03-01

    The response of topological insulators (TIs) to an external weakly classical field can be expressed in terms of Kubo formula, which predicts quantized Hall conductivity of the quantum Hall family. The response of TIs to a single-mode quantized field, however, remains unexplored. In this work, we take the quantum nature of the external field into account and define a Hall conductance to characterize the linear response of a two-band system to the quantized field. The theory is then applied to topological insulators. Comparisons with the traditional Hall conductance are presented and discussed.

  3. Highly optimized tunable Er3+-doped single longitudinal mode fiber ring laser, experiment and model

    DEFF Research Database (Denmark)

    Poulsen, Christian; Sejka, Milan

    1993-01-01

    A continuous wave (CW) tunable diode-pumped Er3+-doped fiber ring laser, pumped by diode laser at wavelengths around 1480 nm, is discussed. Wavelength tuning range of 42 nm, maximum slope efficiency of 48% and output power of 14.4 mW have been achieved. Single longitudinal mode lasing...... with a linewidth of 6 kHz has been measured. A fast model of erbium-doped fiber laser was developed and used to optimize output parameters of the laser...

  4. Mode locking of electron spin coherences in singly charged quantum dots.

    Science.gov (United States)

    Greilich, A; Yakovlev, D R; Shabaev, A; Efros, Al L; Yugova, I A; Oulton, R; Stavarache, V; Reuter, D; Wieck, A; Bayer, M

    2006-07-21

    The fast dephasing of electron spins in an ensemble of quantum dots is detrimental for applications in quantum information processing. We show here that dephasing can be overcome by using a periodic train of light pulses to synchronize the phases of the precessing spins, and we demonstrate this effect in an ensemble of singly charged (In,Ga)As/GaAs quantum dots. This mode locking leads to constructive interference of contributions to Faraday rotation and presents potential applications based on robust quantum coherence within an ensemble of dots.

  5. Stochastic resonance in a single-mode laser driven by frequency modulated signal and coloured noises

    Institute of Scientific and Technical Information of China (English)

    Jin Guo-Xiang; Zhang Liang-Ying; Cao Li

    2009-01-01

    By adding frequency modulated signals to the intensity equation of gain-noise model of the single-mode laser driven by two coloured noises which are correlated, this paper uses the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity. The results show that the SNR appears typical stochastic resonance with the variation of intensity of the pump noise and quantum noise. As the amplitude of a modulated signal has effects on the SNR, it shows suppression, monotone increasing, stochastic resonance, and multiple stochastic resonance with the variation of the frequency of a carrier signal and modulated signal.

  6. Generation efficiency of single-photon current pulses in the Geiger mode of silicon avalanche photodiodes

    International Nuclear Information System (INIS)

    Verkhovtseva, A. V.; Gergel, V. A.

    2009-01-01

    Statistical fluctuations of the avalanche's multiplication efficiency were studied as applied to the single-photon (Geiger) mode of avalanche photodiodes. The distribution function of partial multiplication factors with an anomalously wide (of the order of the average) dispersion was obtained. Expressions for partial feedback factors were derived in terms of the average gain and the corresponding dependences on the diode's overvoltage were calculated. Final expressions for the photon-electric pulse's conversion were derived by averaging corresponding formulas over the coordinate of initiating photoelectron generation using the functions of optical photon absorption in silicon.

  7. Cantilever-based sensor with integrated optical read-out using single mode waveguides

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Calleja, Montserrat

    2007-01-01

    This work presents the design, fabrication and mechanical characterisation of an integrated optical read-out scheme for cantilever-based biosensors. A cantilever can be used as a biosensor by monitoring its bending caused by the surface stress generated due to chemical reactions occurring on its...... surface. Here, we present a novel integrated optical read-out scheme based on single-mode waveguides that enables the fabrication of a compact system. The complete system is fabricated in the polymer SU-8. This manuscript shows the principle of operation and the design well as the fabrication...

  8. Plasma-implantation-based surface modification of metals with single-implantation mode

    Science.gov (United States)

    Tian, X. B.; Cui, J. T.; Yang, S. Q.; Fu, Ricky K. Y.; Chu, Paul K.

    2004-12-01

    Plasma ion implantation has proven to be an effective surface modification technique. Its biggest advantage is the capability to treat the objects with irregular shapes without complex manipulation of target holder. Many metal materials such as aluminum, stainless steel, tool steel, titanium, magnesium etc, has been treated using this technique to improve their wear-resistance, corrosion-resistance, fatigue-resistance, oxidation-resistance, bio-compatiblity etc. However in order to achieve thicker modified layers, hybrid processes combining plasma ion implantation with other techniques have been frequently employed. In this paper plasma implantation based surface modification of metals using single-implantation mode is reviewed.

  9. Single-mode waveguides with SU-8 polymer core and cladding for MOEMS applications

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Boisen, Anja

    2007-01-01

    Fabrication and optical characterization of singlemode polymeric embedded waveguides are performed. A specific material combination (SU-8 2005 as core and the modified SU-8 mr-L 6050XP as cladding) is chosen in order to obtain a small refractive index difference for single-mode propagation combined...... can fabricate waveguides with an index difference in the order of 10−3, where both the core material and the cladding material are based on SU-8. The refractive index measurements are performed on thin polymeric films, while further optical characterizations are performed on waveguides with a height...

  10. Self-pulsing and chaos in inhomogeneously broadened single mode lasers

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R; Cho, Y

    1983-08-01

    A four-dimensional model and a six-dimensional model describing the self-pulsing instabilities and chaotic dynamics of inhomogeneously broadened single-mode lasers are derived as the first two steps of an infinite hierarchy of approximations increasing in accuracy and complexity. The results of a linear stability analysis of the time-independent states and some numerical solutions are given to show the various types of dynamic behavior which can occur in these models. The dynamic behavior is found to be much more complex than in the homogeneously broadened case and is obtained under physically more realistic conditions. 10 references.

  11. Single-longitudinal-mode BEFL incorporating a Bragg grating written in EDF

    Science.gov (United States)

    Gao, Ya; Sun, Junqiang; Chen, Guodong; Xie, Heng

    2015-06-01

    A stable and tunable single-longitudinal-mode (SLM) Brillouin/Erbium fiber laser (BEFL) with narrow linewidth is proposed and experimentally demonstrated. A uniform Bragg grating written in a segment of unpumped Erbium-doped fiber (EDF) is incorporated as an auto-tracking filter to achieve SLM operation. A length of 5 m pumped EDF is used to provide both Brillouin and linear gain in the cavity. The linewidth is measured to be 18 kHz and the lasing peak power fluctuation and wavelength shift are monitored less than 0.027 dB and 2 pm respectively.

  12. Highly damped quasinormal modes of generic single-horizon black holes

    Energy Technology Data Exchange (ETDEWEB)

    Daghigh, Ramin G [Physics Department, University of Winnipeg, Winnipeg, Manitoba R3B 2E9 (Canada); Kunstatter, Gabor [Winnipeg Institute for Theoretical Physics, Winnipeg, Manitoba (Canada)

    2005-10-07

    We calculate analytically the highly damped quasinormal mode spectra of generic single-horizon black holes using the rigorous WKB techniques of Andersson and Howls (2004 Class. Quantum Grav. 21 1623). We thereby provide a firm foundation for previous analysis, and point out some of their possible limitations. The numerical coefficient in the real part of the highly damped frequency is generically determined by the behaviour of coupling of the perturbation to the gravitational field near the origin, as expressed in tortoise coordinates. This fact makes it difficult to understand how the famous ln(3) could be related to the quantum gravitational microstates near the horizon.

  13. Writing single-mode waveguides in lithium niobate by ultra-low intensity solitons

    International Nuclear Information System (INIS)

    Fazio, E.; Ramadan, W.; Petris, A.; Chauvet, M.; Bosco, A.; Vlad, V.I.; Bertolotti, M.

    2005-01-01

    Optical waveguides can be conveniently written in photorefractive materials by using spatial solitons. We have generated bright spatial solitons inside lithium niobate which allow single-mode light propagation. Efficient waveguides have been generated with CW light powers as high as few microwatts. According to the soliton formation, waveguides can be formed with different shapes. Due to the slow response time of the lithium niobate, both for soliton formation and relaxation, the soliton waveguide remains memorised for a long time, of the order of months

  14. Investigation of the glide modes of single crystals of beryllium; Etude des modes de glissement de monocristaux de beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Regnier, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-05-01

    The flow characteristics of single crystals of beryllium specially oriented for slip along a single plane and a single direction have been thoroughly investigated. The elastic limit and the strain hardening in basal glide have been investigated in the temperature range (-195 deg. C, 400 deg. C) in tension as well as in compression. Observation of the slip lines and of the dislocation configurations have also been made in addition to the mechanical tests. The prismatic slip has been studied in greater detail: tensile tests have been performed on specimens carefully oriented at different temperatures, strain rates and with varying orientations of the basal and of the prism planes. Tests have also been made in the micro-strain range; the slip lines and the dislocation arrangements were observed in detail. The very unusual variation of the elastic limit with temperature is not due to impurities but to a cross slip mechanism. A model of dislocation locking is proposed to account for the experimental results. This mechanism assumes that the a-bar dislocations may also dissociate on the prism planes [101-bar 0]. Various possible dissociations are suggested, the most probable of which corresponds to the phase transformation: Hexagonal close packed to body centered cubic. This proposal can be extended to account for the relative ease of glide on the different systems in the hexagonal close packed metals. (author) [French] L' ecoulement de monocristaux de berylliurn deformes en glissement basal et en glissement prismatique a ete etudie sur des echantillons orientes de maniere a favoriser au maximum la deformation suivant une seule direction d'un seul systeme de glissement. L'influence de la temperature sur la limite elastique et la consolidation en glissement basal a ete etudie depuis -195 deg. C jusqu' 400 deg. C sur des echantillons deformes en tension et sur d'autres deformes en compression. Ces essais mecaniques ont ete completes par l'observation des lignes de

  15. Detection of respiratory tumour motion using intrinsic list mode-driven gating in positron emission tomography.

    Science.gov (United States)

    Büther, Florian; Ernst, Iris; Dawood, Mohammad; Kraxner, Peter; Schäfers, Michael; Schober, Otmar; Schäfers, Klaus P

    2010-12-01

    Respiratory motion of organs during PET scans is known to degrade PET image quality, potentially resulting in blurred images, attenuation artefacts and erroneous tracer quantification. List mode-based gating has been shown to reduce these pitfalls in cardiac PET. This study evaluates these intrinsic gating methods for tumour PET scans. A total of 34 patients with liver or lung tumours (14 liver tumours and 27 lung tumours in all) underwent a 15-min single-bed list mode PET scan of the tumour region. Of these, 15 patients (8 liver and 11 lung tumours in total) were monitored by a video camera registering a marker on the patient's abdomen, thus capturing the respiratory motion for PET gating (video method). Further gating information was deduced by dividing the list mode stream into 200-ms frames, determining the number of coincidences (sensitivity method) and computing the axial centre of mass of the measured count rates in the same frames (centre of mass method). Additionally, these list mode-based methods were evaluated using only coincidences originating from the tumour region by segmenting the tumour in sinogram space (segmented sensitivity/centre of mass method). Measured displacement of the tumours between end-expiration and end-inspiration and the increase in apparent uptake in the gated images served as a measure for the exactness of gating. To estimate the accuracy, a thorax phantom study with moved activity sources simulating small tumours was also performed. All methods resolved the respiratory motion with varying success. The best results were seen in the segmented centre of mass method, on average leading to larger displacements and uptake values than the other methods. The simple centre of mass method performed worse in terms of displacements due to activities moving into the field of view during the respiratory cycle. Both sensitivity- and video-based methods lead to similar results. List mode-driven PET gating, especially the segmented centre of mass

  16. Steady-state crack growth in single crystals under Mode I loading

    DEFF Research Database (Denmark)

    Juul, Kristian Jørgensen; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2017-01-01

    The active plastic zone that surrounds the tip of a sharp crack growing under plane strain Mode I loading conditions at a constant velocity in a single crystal is studied. Both the characteristics of the plastic zone and its effect on the macroscopic toughness is investigated in terms of crack tip...... that the largest shielding effect develops in HCP crystals, while the lowest shielding exists for FCC crystals. Rate-sensitivity is found to affect the plastic zone size, but the characteristics overall remain similar for each individual crystal structure. An increasing rate-sensitivity at low crack velocities...... shielding due to plasticity (quantified by employing the Suo, Shih, and Varias set-up). Three single crystals (FCC, BCC, HCP) are modelled in a steady-state elastic visco-plastic framework, with emphasis on the influence of rate-sensitivity and crystal structures. Distinct velocity discontinuities...

  17. Single top quarks at the Tevatron and observation of the s-channel production mode

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    The presentation gives an overview of single-top-quark production at the Tevatron proton-antiproton collider. The talk covers measurements of the total s+t channel production cross section and the extraction of the CKM matrix element |V_tb|. Furthermore, separate analyses of the s-channel and t-channel production modes are discussed. The data correspond to total integrated luminosities of up to 9.7 fb-1 per experiment and represent in most cases the full Run-II dataset. Through a combination of the CDF and D0 measurements the first observation of single-top-quark production in the s-channel is claimed. This is particularly highlighted in the seminar.

  18. Temperature Insensitive Current-Mode Four Quadrant Multiplier Using Single CFCTA

    Directory of Open Access Journals (Sweden)

    Tuntrakool Sunti

    2017-01-01

    Full Text Available A four quadrant multiplier of two current input signals using active building block, namely current follower cascaded transconductance amplifier (CFCTA is presented in this paper. The proposed multiplier consists of only single CFCTA without the use of any passive element. The presented circuit has low impedance at current input node and high impedance at current output node which is convenient for cascading in current mode circuit without the need of current buffer circuits. The output current can multiply two input currents with temperature insensitivity. Moreover, the magnitude of output current can be controlled electronically via DC bias current. With only single active building block, the presented multiplier is suitable for integrated circuit implementation for analog signal processing. Simulation results from a PSpice program are presented in order to demonstrate the multiplier proposed here.

  19. Dynamically controlling the emission of single excitons in photonic crystal cavities

    NARCIS (Netherlands)

    Pagliano, F.; Cho, Y.; Xia, T.; Otten, van F.W.M.; Johne, R.; Fiore, A.

    2014-01-01

    Single excitons in semiconductor microcavities represent a solid state and scalable platform for cavity quantum electrodynamics, potentially enabling an interface between flying (photon) and static (exciton) quantum bits in future quantum networks. While both singlephoton emission and the strong

  20. Anisotropic anti-resonant elements gives broadband single-mode low-loss hollow-core fibers

    DEFF Research Database (Denmark)

    Habib, Selim; Bang, Ole; Bache, Morten

    2016-01-01

    Hollow-core fibers with node-free anisotropic anti-resonant elements give broadband low-loss fibers that are also single-moded. At 1.06 μm silica-based fiber designs show higher-order-mode extinction-ratio >1000 and losses below 10 dB/km over a broad wavelength range....

  1. Tuning the dispersion and single/multi-modeness of a hole-assisted fiber by the hole's geometrical parameters

    NARCIS (Netherlands)

    Uranus, H.P.; Hoekstra, Hugo; van Groesen, Embrecht W.C.

    2008-01-01

    Using a vectorial finite element mode solver developed earlier, we studied a hole-assisted multi-ring fiber. We report the role of the hole’s geometrical parameters in tuning the waveguide dispersion and the single/multi-modeness of the particular fiber. By correctly selecting the hole’s size and

  2. Simple immunoglobulin G sensor based on thin core single-mode fiber

    Science.gov (United States)

    Zheng, Yingfang; Lang, Tingting; Shen, Tingting; Shen, Changyu

    2018-03-01

    In this paper, a simple fiber biosensor (FOB) for immunoglobulin G (IgG) detection is designed and experimentally verified. The FOB is constructed by a 20 mm long thin core single-mode fiber (TCSMF) sandwiched between two single-mode optical fibers (SMFs). First, the refractive index (RI) sensitivity of the fiber structures is calculated by the beam propagation method. The refractive index sensing experiment is performed using different concentrations of glycerol solutions, and the experimental results are mostly consistent with the simulation predictions. The experimental RI sensitivity increases with the surrounding RI and reaches 82.7 nm/RIU. Then the surface of the FOB is functionalized by APTES for covalent bonding. The human IgG and goat anti-human IgG are chosen as a bioconjugated pair to examine the bio-sensing effectiveness of this FOB. The sensitivity of IgG detection is determined to be 10.4 nm/(mg/ml). And the serum IgG concentration in normal adults lies within the range of 6-16 mg/ml (Worsfold et al., 1985), so the sensor is applicable to human IgG monitoring. The specificity of the FOB is also verified by a contrast experiment conducted using rabbit immunoglobulin G. The proposed FOB is simple, low loss, cost-effective, and can be used for various biological and chemical applications.

  3. Probing the limits of Si:P δ-doped devices patterned by a scanning tunneling microscope in a field-emission mode

    Energy Technology Data Exchange (ETDEWEB)

    Rudolph, M.; Carr, S. M.; Ten Eyck, G.; Dominguez, J.; Carroll, M. S.; Bussmann, E. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Subramania, G. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Lilly, M. P. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Pluym, T.

    2014-10-20

    Recently, a single atom transistor was deterministically fabricated using phosphorus in Si by H-desorption lithography with a scanning tunneling microscope (STM). This milestone in precision, achieved by operating the STM in the conventional tunneling mode, typically utilizes slow (∼10{sup 2} nm{sup 2}/s) patterning speeds. By contrast, using the STM in a high-voltage (>10 V) field-emission mode, patterning speeds can be increased by orders of magnitude to ≳10{sup 4} nm{sup 2}/s. We show that the rapid patterning negligibly affects the functionality of relatively large micron-sized features, which act as contacting pads for these devices. For nanoscale structures, we show that the resulting electrical transport is consistent with the donor incorporation chemistry constraining the electrical dimensions to a scale of 10 nm even though the pattering spot size is 40 nm.

  4. Amplified emission and modified spectral features in an opal hetero-structure mediated by passive defect mode localization

    Science.gov (United States)

    Rout, Dipak; Kumar, Govind; Vijaya, R.

    2018-01-01

    A photonic crystal hetero-structure consisting of a passive planar defect of SiO2 thin film sandwiched between two identical opals grown by inward growing self-assembly method using Rhodamine-B dye-doped polystyrene microspheres is studied for the characteristics of dye emission. The optical properties and the defect mode characteristics of the hetero-structure are studied from the reflection and transmission measurements. Laser-induced fluorescence from the hetero-structure showed amplified and spectrally narrowed emission compared to the photonic crystal emphasizing the role of the defect mode and distributed feedback. The enhanced emission is also complemented by the reduction in fluorescence decay time in the case of the hetero-structure in comparison to the 3D photonic crystals.

  5. Fluorescence Intrinsic Characterization of Excitation-Emission Matrix Using Multi-Dimensional Ensemble Empirical Mode Decomposition

    Directory of Open Access Journals (Sweden)

    Tzu-Chien Hsiao

    2013-11-01

    Full Text Available Excitation-emission matrix (EEM fluorescence spectroscopy is a noninvasive method for tissue diagnosis and has become important in clinical use. However, the intrinsic characterization of EEM fluorescence remains unclear. Photobleaching and the complexity of the chemical compounds make it difficult to distinguish individual compounds due to overlapping features. Conventional studies use principal component analysis (PCA for EEM fluorescence analysis, and the relationship between the EEM features extracted by PCA and diseases has been examined. The spectral features of different tissue constituents are not fully separable or clearly defined. Recently, a non-stationary method called multi-dimensional ensemble empirical mode decomposition (MEEMD was introduced; this method can extract the intrinsic oscillations on multiple spatial scales without loss of information. The aim of this study was to propose a fluorescence spectroscopy system for EEM measurements and to describe a method for extracting the intrinsic characteristics of EEM by MEEMD. The results indicate that, although PCA provides the principal factor for the spectral features associated with chemical compounds, MEEMD can provide additional intrinsic features with more reliable mapping of the chemical compounds. MEEMD has the potential to extract intrinsic fluorescence features and improve the detection of biochemical changes.

  6. A new mode of acoustic NDT via resonant air-coupled emission

    Science.gov (United States)

    Solodov, Igor; Dillenz, Alexander; Kreutzbruck, Marc

    2017-06-01

    Resonant modes of non-destructive testing (NDT) which make use of local damage resonance (LDR) have been developed recently and demonstrated a significant increase in efficiency and sensitivity of hybrid inspection techniques by laser vibrometry, ultrasonic thermography, and shearography. In this paper, a new fully acoustic version of resonant NDT is demonstrated for defects in composite materials relevant to automotive and aviation applications. This technique is based on an efficient activation of defect vibrations by using a sonic/ultrasonic wave matched to a fundamental LDR frequency of the defect. On this condition, all points of the faulty area get involved in synchronous out-of-plane vibrations which produce a similar in-phase wave motion in ambient air. This effect of resonant air-coupled emission results in airborne waves emanating from the defect area, which can be received by a commercial microphone (low LDR frequency) or an air-coupled ultrasonic transducer (high frequency LDR). A series of experiments confirm the feasibility of both contact and non-contact versions of the technique for NDT and imaging of simulated and realistic defects (impacts, delaminations, and disbonds) in composites.

  7. Single-Phase Full-Wave Rectifier as an Effective Example to Teach Normalization, Conduction Modes, and Circuit Analysis Methods

    Directory of Open Access Journals (Sweden)

    Predrag Pejovic

    2013-12-01

    Full Text Available Application of a single phase rectifier as an example in teaching circuit modeling, normalization, operating modes of nonlinear circuits, and circuit analysis methods is proposed.The rectifier supplied from a voltage source by an inductive impedance is analyzed in the discontinuous as well as in the continuous conduction mode. Completely analytical solution for the continuous conduction mode is derived. Appropriate numerical methods are proposed to obtain the circuit waveforms in both of the operating modes, and to compute the performance parameters. Source code of the program that performs such computation is provided.

  8. Study of energy transfer in single and multi-emissive layer using Gaussian peak fitting

    International Nuclear Information System (INIS)

    Yoon, Ju-An; Kim, You-Hyun; Kim, Nam Ho; Moon, Chang-Bum; He, Gufeng; Kim, Woo Young

    2014-01-01

    White organic light-emitting diodes(WOLEDs) were fabricated with the device structure of ITO(1800 Å)/NPB(700 Å)/emissive layer(300 Å)/Bphen(300 Å)/Liq(20 Å)/Al(1200 Å) using the two complementary colors method. Then, we investigated their electrical and optical characteristics to determine luminous efficiency, luminance and color coordinates of single, double, triple and quadruple emissive layered-WOLED. Thickness of emissive layer was fixed at 30 Å, and DPASN and BAlq were used for blue emissive host material and DCJTB was added as red dopant in the emissive layer. Then, we investigated the performance of OLEDs via its charge blocking structure and its different emissive region with emissive layers. Luminous efficiency of 5.30 cd/A at 50 mA/cm 2 of current density is obtained in WOLED device with double emissive layer of DPASN:DCJTB-0.1% (150 Å)/BAlq:DCJTB-0.1% (150 Å) and these are 80% higher than WOLED device with single emissive layer of DPASN:DCJTB-0.1% (300 Å). - Highlights: • White OLEDs with multiple-emissive layer were fabricated using p- and n-type emissive materials. • We fabricated WOLEDs only using a small quantity of fluorescent red dopant materials. • The spectroscopic analysis using multi-peak fits with a Gaussian function. • The explain electroluminescence spectra of white OLEDs with the multiple-emissive layer. • We examine changes in the number of emissive layer about white OLEDs performance

  9. Q-switching and efficient harmonic generation from a single-mode LMA photonic bandgap rod fiber laser

    DEFF Research Database (Denmark)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas T.

    2011-01-01

    We demonstrate a Single-Mode (SM) Large-Mode-Area (LMA) ytterbium-doped PCF rod fiber laser with stable and close to diffraction limited beam quality with 110W output power. Distributed-Mode-Filtering (DMF) elements integrated in the cladding of the rod fiber provide a robust spatial mode...... with a Mode-Field-Diameter (MFD) of 59 mu m. We further demonstrate high pulse energy Second-Harmonic-Generation (SHG) and Third Harmonic Generation (THG) using a simple Q-switched single-stage rod fiber laser cavity architecture reaching pulse energies up to 1mJ at 515nm and 0.5mJ at 343nm. (C) 2011 Optical...

  10. Tuning Single Quantum Dot Emission with a Micromirror.

    Science.gov (United States)

    Yuan, Gangcheng; Gómez, Daniel; Kirkwood, Nicholas; Mulvaney, Paul

    2018-02-14

    The photoluminescence of single quantum dots fluctuates between bright (on) and dark (off) states, also termed fluorescence intermittency or blinking. This blinking limits the performance of quantum dot-based devices such as light-emitting diodes and solar cells. However, the origins of the blinking remain unresolved. Here, we use a movable gold micromirror to determine both the quantum yield of the bright state and the orientation of the excited state dipole of single quantum dots. We observe that the quantum yield of the bright state is close to unity for these single QDs. Furthermore, we also study the effect of a micromirror on blinking, and then evaluate excitation efficiency, biexciton quantum yield, and detection efficiency. The mirror does not modify the off-time statistics, but it does change the density of optical states available to the quantum dot and hence the on times. The duration of the on times can be lengthened due to an increase in the radiative recombination rate.

  11. Geometric characterization of separability and entanglement in pure Gaussian states by single-mode unitary operations

    Science.gov (United States)

    Adesso, Gerardo; Giampaolo, Salvatore M.; Illuminati, Fabrizio

    2007-10-01

    We present a geometric approach to the characterization of separability and entanglement in pure Gaussian states of an arbitrary number of modes. The analysis is performed adapting to continuous variables a formalism based on single subsystem unitary transformations that has been recently introduced to characterize separability and entanglement in pure states of qubits and qutrits [S. M. Giampaolo and F. Illuminati, Phys. Rev. A 76, 042301 (2007)]. In analogy with the finite-dimensional case, we demonstrate that the 1×M bipartite entanglement of a multimode pure Gaussian state can be quantified by the minimum squared Euclidean distance between the state itself and the set of states obtained by transforming it via suitable local symplectic (unitary) operations. This minimum distance, corresponding to a , uniquely determined, extremal local operation, defines an entanglement monotone equivalent to the entropy of entanglement, and amenable to direct experimental measurement with linear optical schemes.

  12. Comparison of higher order modes damping techniques for 800 MHz single cell superconducting cavities

    Science.gov (United States)

    Shashkov, Ya. V.; Sobenin, N. P.; Petrushina, I. I.; Zobov, M. M.

    2014-12-01

    At present, applications of 800 MHz harmonic cavities in both bunch lengthening and shortening regimes are under consideration and discussion in the framework of the High Luminosity LHC project. In this paper we study electromagnetic characteristics of high order modes (HOMs) for a single cell 800 MHz superconducting cavity and arrays of such cavities connected by drifts tubes. Different techniques for the HOMs damping such as beam pipe grooves, coaxial-notch loads, fluted beam pipes etc. are investigated and compared. The influence of the sizes and geometry of the drift tubes on the HOMs damping is analyzed. The problems of a multipacting discharge in the considered structures are discussed and the operating frequency detuning due to the Lorentz force is evaluated.

  13. Stochastic resonance for signal-modulated pump noise in a single-mode laser

    Institute of Scientific and Technical Information of China (English)

    Liangying Zhang; Li Cao; Fahui Zhu

    2006-01-01

    By adopting the gain-noise model of the single-mode laser in which with bias and periodical signals serve as inputs, combining with the effect of coloured pump noise, we use the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity under the condition of pump noise and quantum noise cross-related in the form of δ function. It is found that with the change of pump noise correlation time, both SNR and the output power will occur stochastic resonance (SR). If the bias signal α is very small, changing the intensities of pump noise and quantum noise respectively does not lead to the appearance of SR in the SNR; while α increases to a certain number, SR appears.

  14. Geometric characterization of separability and entanglement in pure Gaussian states by single-mode unitary operations

    International Nuclear Information System (INIS)

    Adesso, Gerardo; Giampaolo, Salvatore M.; Illuminati, Fabrizio

    2007-01-01

    We present a geometric approach to the characterization of separability and entanglement in pure Gaussian states of an arbitrary number of modes. The analysis is performed adapting to continuous variables a formalism based on single subsystem unitary transformations that has been recently introduced to characterize separability and entanglement in pure states of qubits and qutrits [S. M. Giampaolo and F. Illuminati, Phys. Rev. A 76, 042301 (2007)]. In analogy with the finite-dimensional case, we demonstrate that the 1xM bipartite entanglement of a multimode pure Gaussian state can be quantified by the minimum squared Euclidean distance between the state itself and the set of states obtained by transforming it via suitable local symplectic (unitary) operations. This minimum distance, corresponding to a, uniquely determined, extremal local operation, defines an entanglement monotone equivalent to the entropy of entanglement, and amenable to direct experimental measurement with linear optical schemes

  15. Comparison of higher order modes damping techniques for 800 MHz single cell superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Shashkov, Ya.V., E-mail: shashkovyv@mail.ru [National Research Nuclear University MEPhI, Moscow (Russian Federation); Sobenin, N.P.; Petrushina, I.I. [National Research Nuclear University MEPhI, Moscow (Russian Federation); Zobov, M.M. [Laboratori Nazionali di Frascati INFN, Rome (Italy)

    2014-12-11

    At present, applications of 800 MHz harmonic cavities in both bunch lengthening and shortening regimes are under consideration and discussion in the framework of the High Luminosity LHC project. In this paper we study electromagnetic characteristics of high order modes (HOMs) for a single cell 800 MHz superconducting cavity and arrays of such cavities connected by drifts tubes. Different techniques for the HOMs damping such as beam pipe grooves, coaxial-notch loads, fluted beam pipes etc. are investigated and compared. The influence of the sizes and geometry of the drift tubes on the HOMs damping is analyzed. The problems of a multipacting discharge in the considered structures are discussed and the operating frequency detuning due to the Lorentz force is evaluated.

  16. Semiconductor laser engineering, reliability and diagnostics a practical approach to high power and single mode devices

    CERN Document Server

    Epperlein, Peter W

    2013-01-01

    This reference book provides a fully integrated novel approach to the development of high-power, single-transverse mode, edge-emitting diode lasers by addressing the complementary topics of device engineering, reliability engineering and device diagnostics in the same book, and thus closes the gap in the current book literature. Diode laser fundamentals are discussed, followed by an elaborate discussion of problem-oriented design guidelines and techniques, and by a systematic treatment of the origins of laser degradation and a thorough exploration of the engineering means to enhance the optical strength of the laser. Stability criteria of critical laser characteristics and key laser robustness factors are discussed along with clear design considerations in the context of reliability engineering approaches and models, and typical programs for reliability tests and laser product qualifications. Novel, advanced diagnostic methods are reviewed to discuss, for the first time in detail in book literature, performa...

  17. Interaction of a single mode field cavity with the 1D XY model: Energy spectrum

    International Nuclear Information System (INIS)

    Tonchev, H; Donkov, A A; Chamati, H

    2016-01-01

    In this work we use the fundamental in quantum optics Jaynes-Cummings model to study the response of spin 1/2chain to a single mode of a laser light falling on one of the spins, a focused interaction model between the light and the spin chain. For the spin-spin interaction along the chain we use the XY model. We report here the exact analytical results, obtained with the help of a computer algebra system, for the energy spectrum in this model for chains of up to 4 spins with nearest neighbors interactions, either for open or cyclic chain configurations. Varying the sign and magnitude of the spin exchange coupling relative to the light-spin interaction we have investigated both cases of ferromagnetic or antiferromagnetic spin chains. (paper)

  18. PREPARATION OF THE SINGLE MODE PLANAR OPTICAL SPLITTER MODULES AND THEIR CHARACTERIZATIONS

    Directory of Open Access Journals (Sweden)

    Vu Doan Mien

    2017-11-01

    Full Text Available Optical splitter modules have been prepared based on 1x8 single mode silica planar waveguide optical splitter chips with 250 µm spacing and v-groove fiber arrays for applications in fiber optic communications. We report the technology of precise optical coupling and packaging of the splitter modules and the measurements of the insertion loss (< 11 dB,  uniformity (< 0.80 dB and polarization dependence loss (PLD < 0.10 dB as well as the lateral profile and the image of the input and output lights for the wavelengths of 1310 nm and 1550 nm. The main characteristics of the prepared splitter modules are about the same for the commercial available products. The prepared modules have been tested for operation in the conditions of wide temperature range (5–80°C and humidity range (50–98% and no changes in the main characteristics were observed.

  19. A long-baseline interferometer employing single-mode fiber optics

    Science.gov (United States)

    Shaklan, Stuart

    The idea of the Fiber-Linked Optical Array Telescope proposed by Connes (1987) is to mount several small optical telescopes around the perimeter of a radio dish or other large steerable structure, couple the light into single-mode (SM) fibers, and use the fibers to coherently combine the beams at the output. This paper examines the important properties of SM fibers and then discusses the whole system in general terms, starting with the telescopes and following the light through to the detectors, along with the results of laboratory experiments evaluating the performance of SM fibers. The imaging capabilities of the array were simulated, and it was found that, using 10 telescopes on a 440-m dish, the array obtains images with resolution of the order of 2 milliarc seconds in the visible range.

  20. High energy, single frequency, tunable laser source operating in burst mode for space based lidar applications

    Science.gov (United States)

    Cosentino, Alberto; Mondello, Alessia; Sapia, Adalberto; D'Ottavi, Alessandro; Brotini, Mauro; Gironi, Gianna; Suetta, Enrico

    2017-11-01

    This paper describes energetic, spatial, temporal and spectral characterization measurements of the Engineering Qualification Model (EQM) of the Laser Transmitter Assembly (TXA) used in the ALADIN instrument currently under development for the ESA ADM-AEOLUS mission (EADS Astrium as prime contractor for the satellite and the instrument). The EQM is equivalent to the Flight Model, with the exception of some engineering grade components. The Laser Transmitter Assembly, based on a diode pumped tripled Nd:YAG laser, is used to generate laser pulses at a nominal wavelength of 355 nm. This laser is operated in burst mode, with a pulse repetition cycle of 100 Hz during bursts. It is capable to operate in Single Longitudinal Mode and to be tuned over 25 GHz range. An internal "network" of sensors has been implemented inside the laser architecture to allow "in flight" monitoring of transmitter. Energy in excess of 100 mJ, with a spatial beam quality factor (M2) lower than 3, a spectral linewidth less than 50 MHz with a frequency stability better than 4 MHz on short term period have been measured on the EQM. Most of the obtained results are well within the expected values and match the Instrument requirements. They constitute an important achievement, showing the absence of major critical areas in terms of performance and the capability to obtain them in a rugged and compact structure suitable for space applications. The EQM will be submitted in the near future to an Environmental test campaign.

  1. Trapped-ion anomalous diffusion coefficient on the basis of single mode saturation

    International Nuclear Information System (INIS)

    Koshi, Yuji; Hatayama, Akiyoshi; Ogasawara, Masatada.

    1982-03-01

    Expressions of the anomalous diffusion coefficient due to the dissipative trapped ion instability (DTII) are derived for the case with and without the effect of magnetic shear. Derivation is made by taking into account of the single mode saturation of the DTII previously obtained numerically. In the absence of the shear effect, the diffusion coefficient is proportional to #betta#sub(i)a 2 (#betta#sub(i) is the effective collision frequency of the trapped ions and a is the minor radius of a torus) and is much larger than the neoclassical ion heat conductivity. In the presence of the shear effect, the diffusion coefficient is much smaller than the Kadomtsev and Pogutse's value and is the same order of magnitude as the neoclassical ion heat conductivity. Dependences of the diffusion coefficient on the temperature and on the total particle number density are rather complicated due to the additional spectral cut-off, which is introduced to regularize the short wavelength modes in the numerical analysis. (author)

  2. Tunneling Mode of Scanning Electrochemical Microscopy: Probing Electrochemical Processes at Single Nanoparticles.

    Science.gov (United States)

    Sun, Tong; Wang, Dengchao; Mirkin, Michael V

    2018-06-18

    Electrochemical experiments at individual nanoparticles (NPs) can provide new insights into their structure-activity relationships. By using small nanoelectrodes as tips in a scanning electrochemical microscope (SECM), we recently imaged individual surface-bound 10-50 nm metal NPs. Herein, we introduce a new mode of SECM operation based on tunneling between the tip and a nanoparticle immobilized on the insulating surface. The obtained current vs. distance curves show the transition from the conventional feedback response to electron tunneling between the tip and the NP at separation distances of less than about 3 nm. In addition to high-resolution imaging of the NP topography, the tunneling mode enables measurement of the heterogeneous kinetics at a single NP without making an ohmic contact with it. The developed method should be useful for studying the effects of nanoparticle size and geometry on electrocatalytic activity in real-world applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Multipacting and higher order mode analysis of 325 MHz single spoke resonators

    International Nuclear Information System (INIS)

    Pal, Mukesh Kumar; Gaur, Rahul; Kumar, Vinit

    2015-01-01

    Superconducting Single Spoke Resonators (SSRs) will be used to accelerate the H - ions from 3 MeV to 160 MeV in the injector linac for the proposed Indian Spallation Neutron Source (ISNS) at RRCAT. Electromagnetic design studies of 325 MHz SSRs have been performed for βg = 0.11, 0.22 and 0.42. Performance of SSRs are typically limited by multipacting phenomenon and higher order modes. In our design, we have performed detailed studies of electron multipacting phenomenon, which is a resonant process, using a computer code CST-PS. Based on this analysis, refinements in the geometry of the SSRs have been made, in order to reduce the growth rate of multipacting. We have also carried out extensive analysis of Higher Order Mode (HOM) for the SSR structure, using the computer code CST-MWS, where the R/Q parameter has been calculated for monopole, dipole and quadrupole HaMs. Details of these calculations will be presented in this paper. (author)

  4. Interferometric measurement of refractive index modification in a single mode microfiber

    Science.gov (United States)

    Ahmed, Farid; Ahsani, Vahid; Jun, Martin B. G.

    2017-02-01

    Efficient and cost effective measurement of the refractive index profile in an optical fiber is a significant technical job to design and manufacture in-fiber photonic devices and communication systems. For instance, to design fiber gratings, it is required to estimate the refractive index modulation to be inscribed by the fabrication apparatus such as ultraviolet or infrared lasers. Mach-Zehnder interferometer (MZI) based quantification of refractive index change written in single mode microfiber by femtosecond laser radiation is presented in this study. The MZI is constructed by splicing a microfiber (core diameter: 3.75 μm, cladding diameter: 40 μm) between standard single mode fibers. To measure the RI inscribed by infrared femtosecond laser, 200 μm length of the core within the MZI was scanned with laser radiation. As the higher index was written within 200 μm length of the core, the transmission spectrum of the interferometer displayed a corresponding red shift. The observed spectral shift was used to calculate the amount of refractive index change inscribed by the femtosecond irradiation. For the MZI length of 3.25 mm, and spectral shift of 0.8 nm, the calculated refractive index was found to be 0.00022. The reported results display excellent agreement between theory and experimental findings. Demonstrated method provides simple yet very effective on-site measurement of index change in optical fibers. Since the MZI can be constructed in diverse fiber types, this technique offers flexibility to quantify index change in various optical fibers.

  5. Silicon photonics WDM transmitter with single section semiconductor mode-locked laser

    Science.gov (United States)

    Müller, Juliana; Hauck, Johannes; Shen, Bin; Romero-García, Sebastian; Islamova, Elmira; Azadeh, Saeed Sharif; Joshi, Siddharth; Chimot, Nicolas; Moscoso-Mártir, Alvaro; Merget, Florian; Lelarge, François; Witzens, Jeremy

    2015-04-01

    We demonstrate a wavelength domain-multiplexed (WDM) optical link relying on a single section semiconductor mode-locked laser (SS-MLL) with quantum dash (Q-Dash) gain material to generate 25 optical carriers spaced by 60.8 GHz, as well as silicon photonics (SiP) resonant ring modulators (RRMs) to modulate individual optical channels. The link requires optical reamplification provided by an erbium-doped fiber amplifier (EDFA) in the system experiments reported here. Open eye diagrams with signal quality factors (Q-factors) above 7 are measured with a commercial receiver (Rx). For higher compactness and cost effectiveness, reamplification of the modulated channels with a semiconductor optical amplifier (SOA) operated in the linear regime is highly desirable. System and device characterization indicate compatibility with the latter. While we expect channel counts to be primarily limited by the saturation output power level of the SOA, we estimate a single SOA to support more than eight channels. Prior to describing the system experiments, component design and detailed characterization results are reported including design and characterization of RRMs, ring-based resonant optical add-drop multiplexers (RR-OADMs) and thermal tuners, S-parameters resulting from the interoperation of RRMs and RR-OADMs, and characterization of Q-Dash SS-MLLs reamplified with a commercial SOA. Particular emphasis is placed on peaking effects in the transfer functions of RRMs and RR-OADMs resulting from transient effects in the optical domain, as well as on the characterization of SS-MLLs in regard to relative intensity noise (RIN), stability of the modes of operation, and excess noise after reamplification.

  6. Coupling single NV-centres to high-Q whispering gallery modes of a preselected frequency-matched microresonator

    International Nuclear Information System (INIS)

    Schietinger, Stefan; Benson, Oliver

    2009-01-01

    In this paper, we report the controlled coupling of fluorescence from a single NV-centre in a single nanodiamond to the high-Q modes of a preselected microsphere. Microspheres from an ensemble with a finite size distribution can be characterized precisely via white light Mie-scattering. The mode spectrum of individual spheres can be determined with high precision. A sphere with an appropriate spectrum can be selected, and a nanodiamond containing a single NV-centre can be coupled to it. The spectral position of the calculated lowest order whispering gallery modes are found to be in very good agreement with the experimentally observed resonances of the coupled fluorescence from the single NV-re.

  7. Conversion of electrostatic upper hybrid emissions to electromagnetic O and X mode waves in the Earth's magnetosphere

    International Nuclear Information System (INIS)

    Budden, K.G.; Jones, D.

    1987-01-01

    The linear conversion of electrostatic upper hybrid emissions via the Z mode to electromagnetic ordinary (O) mode waves has for some time been invoked for the source of Terrestrial and Saturnian myriametric and Jovian kilometric radiations. The conversion occurs by virtue of the emissions' propagation in concentration gradients, and for it to be efficient it is necessary for the gradient to be normal to the ambient magnetic field. Suitable concentration gradients are believed to occur at the plasmapause and at the magnetopause. Ray theory predicts only O mode production whereas full wave theory in a cold plasma shows that both O and X (extraordinary) mode are produced, their relative intensities depending on the plasma parameters. Full wave theory in a warm plasma, besides yielding more accurate information on the O and X modes also provides an insight into the effect of conversion on the source plasma wave. Results obtained from these three levels of theory are compared using plasma parameters derived from wave experiments on spacecraft

  8. Conversion of electrostatic upper hybrid emissions to electromagnetic O and X mode waves in the Earth's magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Budden, K.G.; Jones, D.

    1987-02-01

    The linear conversion of electrostatic upper hybrid emissions via the Z mode to electromagnetic ordinary (O) mode waves has for some time been invoked for the source of Terrestrial and Saturnian myriametric and Jovian kilometric radiations. The conversion occurs by virtue of the emissions' propagation in concentration gradients, and for it to be efficient it is necessary for the gradient to be normal to the ambient magnetic field. Suitable concentration gradients are believed to occur at the plasmapause and at the magnetopause. Ray theory predicts only O mode production whereas full wave theory in a cold plasma shows that both O and X (extraordinary) mode are produced, their relative intensities depending on the plasma parameters. Full wave theory in a warm plasma, besides yielding more accurate information on the O and X modes also provides an insight into the effect of conversion on the source plasma wave. Results obtained from these three levels of theory are compared using plasma parameters derived from wave experiments on spacecraft.

  9. A tuneable, power efficient and narrow single longitudinal mode fibre ring laser using an inline dual-taper fibre Mach–Zehnder filter

    International Nuclear Information System (INIS)

    Ahmad, H; Dernaika, M; Alimadad, M; Ibrahim, M F; Lim, K S; Harun, S W; Kharraz, O M

    2014-01-01

    A tuneable single longitudinal mode fibre ring laser with dual-taper fibre filter is proposed and experimentally demonstrated in this paper. The single longitudinal mode operation, and power limitations for a Mach–Zehnder interferometer filter generated from a single mode fibre, are verified for the first time. Incorporating an in-line taper fibre Mach–Zehnder interferometer filter inside the laser ring cavity causes a spatial mode beating interference, resulting in a passive narrow band filter with the ability to generate stable single longitudinal modes. The single longitudinal mode achieves a side mode suppression ratio of more than 60 dB using low pump power. The tuneability of the fibre laser ranges from 1525 to 1562 nm using a passive band pass filter. A study of the stability and limitation of the single longitudinal mode in the Mach–Zehnder tapered fibre is also presented. (paper)

  10. Systematic analysis of whistler-mode emissions below the lower hybrid frequency based on the data of the Cluster project.

    Science.gov (United States)

    Nemec, F.; Santolik, O.; Gereova, K.; Macusova, E.; Cornilleau-Wehrlin, N.

    2003-12-01

    We report results of a systematic analysis of equatorial noise below the local lower hybrid frequency. Our analysis is based on the entire data set collected by the STAFF-SA instruments on board the Cluster spacecraft during the first two years of operation (2001 - 2002). We compare intensities of equatorial noise with other whistler-mode emissions, for example with chorus or hiss. The results indicate that these emissions can play a significant role in the dynamics of the inner magnetosphere. Using the multipoint measurement we show considerable spatio-temporal variations of the wave intensity.

  11. A Single Mode Study of a Quasi-Geostrophic Convection-Driven Dynamo Model

    Science.gov (United States)

    Plumley, M.; Calkins, M. A.; Julien, K. A.; Tobias, S.

    2017-12-01

    Planetary magnetic fields are thought to be the product of hydromagnetic dynamo action. For Earth, this process occurs within the convecting, turbulent and rapidly rotating outer core, where the dynamics are characterized by low Rossby, low magnetic Prandtl and high Rayleigh numbers. Progress in studying dynamos has been limited by current computing capabilities and the difficulties in replicating the extreme values that define this setting. Asymptotic models that embrace these extreme parameter values and enforce the dominant balance of geostrophy provide an option for the study of convective flows with actual relevance to geophysics. The quasi-geostrophic dynamo model (QGDM) is a multiscale, fully-nonlinear Cartesian dynamo model that is valid in the asymptotic limit of low Rossby number. We investigate the QGDM using a simplified class of solutions that consist of a single horizontal wavenumber which enforces a horizontal structure on the solutions. This single mode study is used to explore multiscale time stepping techniques and analyze the influence of the magnetic field on convection.

  12. Mode I fracture toughness analysis of a single-layer grapheme sheet

    Energy Technology Data Exchange (ETDEWEB)

    Ky, Minh Nguyen; Yum, Young Jin [University of Ulsan, Ulsan (Korea, Republic of)

    2014-09-15

    To predict the fracture toughness of a single-layer graphene sheet (SLGS), analytical formulations were devised for the hexagonal honeycomb lattice using a linkage equivalent discrete frame structure. Broken bonds were identified by a sharp increase in the position of the atoms. As crack propagation progressed, the crack tip position and crack path were updated from broken bonds in the molecular dynamics (MD) model. At each step in the simulation, the atomic model was centered on the crack tip to adaptively follow its path. A new formula was derived analytically from the deformation and bending mechanism of solid-state carbon-carbon bonds so as to describe the mode I fracture of SLGS. The fracture toughness of single-layer graphene is governed by a competition between bond breaking and bond rotation at a crack tip. K-field based displacements were applied on the boundary of the micromechanical model, and FEM results were obtained and compared with theoretical findings. The critical stress intensity factor for a graphene sheet was found to be K{sub IC} = 2.63 ∼ 3.2 MPa√m for the case of a zigzag crack.

  13. Dual-mode optical microscope based on single-pixel imaging

    Science.gov (United States)

    Rodríguez, A. D.; Clemente, P.; Tajahuerce, E.; Lancis, J.

    2016-07-01

    We demonstrate an inverted microscope that can image specimens in both reflection and transmission modes simultaneously with a single light source. The microscope utilizes a digital micromirror device (DMD) for patterned illumination altogether with two single-pixel photosensors for efficient light detection. The system, a scan-less device with no moving parts, works by sequential projection of a set of binary intensity patterns onto the sample that are codified onto a modified commercial DMD. Data to be displayed are geometrically transformed before written into a memory cell to cancel optical artifacts coming from the diamond-like shaped structure of the micromirror array. The 24-bit color depth of the display is fully exploited to increase the frame rate by a factor of 24, which makes the technique practicable for real samples. Our commercial DMD-based LED-illumination is cost effective and can be easily coupled as an add-on module for already existing inverted microscopes. The reflection and transmission information provided by our dual microscope complement each other and can be useful for imaging non-uniform samples and to prevent self-shadowing effects.

  14. Design and Characterization of 64K Pixels Chips Working in Single Photon Processing Mode

    CERN Document Server

    Llopart Cudie, Xavier; Campbell, M

    2007-01-01

    Progress in CMOS technology and in fine pitch bump bonding has made possible the development of high granularity single photon counting detectors for X-ray imaging. This thesis studies the design and characterization of three pulse processing chips with 65536 square pixels of 55 µm x 55 µm designed in a commercial 0.25 µm 6-metal CMOS technology. The 3 chips share the same architecture and dimensions and are named Medipix2, Mpix2MXR20 and Timepix. The Medipix2 chip is a pixel detector readout chip consisting of 256 x 256 identical elements, each working in single photon counting mode for positive or negative input charge signals. The preamplifier feedback provides compensation for detector leakage current on a pixel by pixel basis. Two identical pulse height discriminators are used to define an energy window. Every event falling inside the energy window is counted with a 13 bit pseudo-random counter. The counter logic, based in a shift register, also behaves as the input/output register for the pixel. Each...

  15. Geiger-mode APD camera system for single-photon 3D LADAR imaging

    Science.gov (United States)

    Entwistle, Mark; Itzler, Mark A.; Chen, Jim; Owens, Mark; Patel, Ketan; Jiang, Xudong; Slomkowski, Krystyna; Rangwala, Sabbir

    2012-06-01

    The unparalleled sensitivity of 3D LADAR imaging sensors based on single photon detection provides substantial benefits for imaging at long stand-off distances and minimizing laser pulse energy requirements. To obtain 3D LADAR images with single photon sensitivity, we have demonstrated focal plane arrays (FPAs) based on InGaAsP Geiger-mode avalanche photodiodes (GmAPDs) optimized for use at either 1.06 μm or 1.55 μm. These state-of-the-art FPAs exhibit excellent pixel-level performance and the capability for 100% pixel yield on a 32 x 32 format. To realize the full potential of these FPAs, we have recently developed an integrated camera system providing turnkey operation based on FPGA control. This system implementation enables the extremely high frame-rate capability of the GmAPD FPA, and frame rates in excess of 250 kHz (for 0.4 μs range gates) can be accommodated using an industry-standard CameraLink interface in full configuration. Real-time data streaming for continuous acquisition of 2 μs range gate point cloud data with 13-bit time-stamp resolution at 186 kHz frame rates has been established using multiple solid-state storage drives. Range gate durations spanning 4 ns to 10 μs provide broad operational flexibility. The camera also provides real-time signal processing in the form of multi-frame gray-scale contrast images and single-frame time-stamp histograms, and automated bias control has been implemented to maintain a constant photon detection efficiency in the presence of ambient temperature changes. A comprehensive graphical user interface has been developed to provide complete camera control using a simple serial command set, and this command set supports highly flexible end-user customization.

  16. Real-time control of tearing modes using a line-of-sight electron cyclotron emission diagnostic

    International Nuclear Information System (INIS)

    Hennen, B A; Westerhof, E; De Baar, M R; Bongers, W A; Thoen, D J; Nuij, P W J M; Steinbuch, M; Oosterbeek, J W; Buerger, A

    2010-01-01

    The stability and performance of tokamak plasmas are limited by instabilities such as neoclassical tearing modes. This paper reports on an experimental proof of principle of a feedback control approach for real-time, autonomous suppression and stabilization of tearing modes in a tokamak. The system combines an electron cyclotron emission diagnostic for sensing of the tearing modes in the same sight line with a steerable electron cyclotron resonance heating and current drive (ECRH/ECCD) antenna. A methodology for fast detection of q = m/n = 2/1 tearing modes and retrieval of their location, rotation frequency and phase is presented. Set-points to establish alignment of the ECRH/ECCD deposition location with the centre of the tearing mode are generated in real time and forwarded in closed loop to the steerable launcher and as a modulation pulse train to the gyrotron. Experimental results demonstrate the capability of the control system to track externally perturbed tearing modes in real time.

  17. Field emission of carbon quantum dots synthesized from a single organic solvent.

    Science.gov (United States)

    Liu, Xiahui; Yang, Bingjun; Yang, Juan; Yu, Shengxue; Chen, Jiangtao

    2016-11-04

    In this paper, a facile synthesis of carbon quantum dots (CQDs) and its field emission performance are reported. The CQDs are prepared from a single N, N-dimethylformamide acting as carbon and nitrogen-doping sources simultaneously. The CQDs are investigated by photoluminescence, transmission electron microscopy and x-ray photoelectron spectroscopy. The CQDs have an average size of 3 nm and are doped with N atoms. CQD dispersion shows strong fluorescence under UV illumination. For the first time, the field emission behavior of CQDs coated on Si substrate is studied. As a candidate of cold cathode, the CQDs display good field emission performance. The CQD emitter reaches the current density of 1.1 mA cm(-2) at 7.0 V μm(-1) and exhibits good long-term emission stability, suggesting promising application in field emission devices.

  18. Emissions gazeuses en élevage porcin et mode de réduction : revue bibliographique

    Directory of Open Access Journals (Sweden)

    Degre A.

    2001-01-01

    Full Text Available Gaseous emissions in pig husbandry and measures of reduction : a review. Atmospheric emissions of pig husbandry are studied at the level of the farm building, storage area and land used for spreading. The process leading to formation of NH3,N2O, CH4 and various smelling gases, the parameters controlling their level of emission, and their effects are described. Emission of molecular nitrogen is also addressed. Measures for reducing atmospheric emissions are detailed. They rely on animal feeding, design of farm building and storage area, air treatments, effluent management and disposal. The sub-products of the effluents are also considered. The costs of the techniques used to reduce gas emissions are detailed in BEF per weight of carcass. This document gives evidence that the most effective measures to reduce the emissions are linked to the design of the farm buildings and the storage of the effluents.

  19. 3 kW single stage all-fiber Yb-doped single-mode fiber laser for highly reflective and highly thermal conductive materials processing

    Science.gov (United States)

    Ikoma, S.; Nguyen, H. K.; Kashiwagi, M.; Uchiyama, K.; Shima, K.; Tanaka, D.

    2017-02-01

    A 3 kW single stage all-fiber Yb-doped single-mode fiber laser with bi-directional pumping configuration has been demonstrated. Our newly developed high-power LD modules are employed for a high available pump power of 4.9 kW. The length of the delivery fiber is 20 m which is long enough to be used in most of laser processing machines. An output power of 3 kW was achieved at a pump power of 4.23 kW. The slope efficiency was 70%. SRS was able to be suppressed at the same output power by increasing ratio of backward pump power. The SRS level was improved by 5dB when 57% backward pump ratio was adopted compared with the case of 50%. SRS was 35dB below the laser power at the output power of 3 kW even with a 20-m delivery fiber. The M-squared factor was 1.3. Single-mode beam quality was obtained. To evaluate practical utility of the 3 kW single-mode fiber laser, a Bead-on-Plate (BoP) test onto a pure copper plate was executed. The BoP test onto a copper plate was made without stopping or damaging the laser system. That indicates our high power single-mode fiber lasers can be used practically in processing of materials with high reflectivity and high thermal conductivity.

  20. Toward single-mode random lasing within a submicrometre-sized spherical ZnO particle film

    International Nuclear Information System (INIS)

    Niyuki, Ryo; Fujiwara, Hideki; Sasaki, Keiji; Ishikawa, Yoshie; Koshizaki, Naoto; Tsuji, Takeshi

    2016-01-01

    We had recently reported unique random laser action such as quasi-single-mode and low-threshold lasing from a submicrometre-sized spherical ZnO nanoparticle film with polymer particles as defects. The present study demonstrates a novel approach to realize single-mode random lasing by adjusting the sizes of the defect particles. From the dependence of random lasing properties on defect size, we find that the average number of lasing peaks can be modified by the defect size, while other lasing properties such as lasing wavelengths and thresholds remain unchanged. These results suggest that lasing wavelengths and thresholds are determined by the resonant properties of the surrounding scatterers, while the defect size stochastically determines the number of lasing peaks. Therefore, if we optimize the sizes of the defects and scatterers, we can intentionally induce single-mode lasing even in a random structure (Fujiwara et al 2013 Appl. Phys. Lett. 102 061110). (paper)

  1. Dynamics of a Dispersion-Managed Passively Mode-Locked Er-Doped Fiber Laser Using Single Wall Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Norihiko Nishizawa

    2015-07-01

    Full Text Available We investigated the dynamics of a dispersion-managed, passively mode-locked, ultrashort-pulse, Er-doped fiber laser using a single-wall carbon nanotube (SWNT device. A numerical model was constructed for analysis of the SWNT fiber laser. The initial process of passive mode-locking, the characteristics of the output pulse, and the dynamics inside the cavity were investigated numerically for soliton, dissipative-soliton, and stretched-pulse mode-locking conditions. The dependencies on the total dispersion and recovery time of the SWNTs were also examined. Numerical results showed similar behavior to experimental results.

  2. Single-mode temperature and polarisation-stable high-speed 850nm vertical cavity surface emitting lasers

    International Nuclear Information System (INIS)

    Nazaruk, D E; Blokhin, S A; Maleev, N A; Bobrov, M A; Pavlov, M M; Kulagina, M M; Vashanova, K A; Zadiranov, Yu M; Ustinov, V M; Kuzmenkov, A G; Vasil'ev, A P; Gladyshev, A G; Blokhin, A A; Salut, 7 Larina Str, N Novgorod, 603950 (Russian Federation))" data-affiliation=" (JSV Salut, 7 Larina Str, N Novgorod, 603950 (Russian Federation))" >Fefelov, A G

    2014-01-01

    A new intracavity-contacted design to realize temperature and polarization-stable high-speed single-mode 850 nm vertical cavity surface emitting lasers (VCSELs) grown by molecular-beam epitaxy is proposed. Temperature dependences of static and dynamic characteristics of the 4.5 pm oxide aperture InGaAlAs VCSEL were investigated in detail. Due to optimal gain-cavity detuning and enhanced carrier localization in the active region the threshold current remains below 0.75 mA for the temperature range within 20-90°C, while the output power exceeds 1 mW up to 90°C. Single-mode operation with side-mode suppression ratio higher than 30 dB and orthogonal polarization suppression ratio more than 18 dB was obtained in the whole current and temperature operation range. Device demonstrates serial resistance less than 250 Ohm, which is rather low for any type of single-mode short- wavelength VCSELs. VCSEL demonstrates temperature robust high-speed operation with modulation bandwidth higher than 13 GHz in the entire temperature range of 20-90°C. Despite high resonance frequency the high-speed performance of developed VCSELs was limited by the cut-off frequency of the parasitic low pass filter created by device resistances and capacitances. The proposed design is promising for single-mode high-speed VCSEL applications in a wide spectral range

  3. Multi-wavelength emission from a single InGaN/GaN nanorod analyzed by cathodoluminescence hyperspectral imaging

    KAUST Repository

    Kusch, Gunnar

    2018-01-23

    Multiple luminescence peaks emitted by a single InGaN/GaN quantum-well(QW) nanorod, extending from the blue to the red, were analysed by a combination of electron microscope based imaging techniques. Utilizing the capability of cathodoluminescence hyperspectral imaging it was possible to investigate spatial variations in the luminescence properties on a nanoscale. The high optical quality of a single GaN nanorod was demonstrated, evidenced by a narrow band-edge peak and the absence of any luminescence associated with the yellow defect band. Additionally two spatially confined broad luminescence bands were observed, consisting of multiple peaks ranging from 395 nm to 480 nm and 490 nm to 650 nm. The lower energy band originates from broad c-plane QWs located at the apex of the nanorod and the higher energy band from the semipolar QWs on the pyramidal nanorod tip. Comparing the experimentally observed peak positions with peak positions obtained from plane wave modelling and 3D finite difference time domain(FDTD) modelling shows modulation of the nanorod luminescence by cavity modes. By studying the influence of these modes we demonstrate that this can be exploited as an additional parameter in engineering the emission profile of LEDs.

  4. Yb-doped rod-type photonic crystal fibers for single-mode amplification

    DEFF Research Database (Denmark)

    Poli, Frederica; Passaro, Davide; Cucinotta, Annamaria

    2009-01-01

    The competition among the guided modes in rod-type photonic crystal fibers with a low refractive index ring in the Yb-doped core is investigated with an amplifier model to demonstrate the effective higher-order mode suppression.......The competition among the guided modes in rod-type photonic crystal fibers with a low refractive index ring in the Yb-doped core is investigated with an amplifier model to demonstrate the effective higher-order mode suppression....

  5. Single-mode solid-state polymer dye laser fabricated with standard I-line UV lithography

    DEFF Research Database (Denmark)

    Balslev, Søren; Mironov, Andrej; Nilsson, Daniel

    2005-01-01

    We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G.......We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G....

  6. Controlling light emission from single-photon sources using photonic nanowires

    DEFF Research Database (Denmark)

    Gregersen, Niels; Chen, Yuntian; Mørk, Jesper

    2012-01-01

    The photonic nanowire has recently emerged as an promising alternative to microcavity-based single-photon source designs. In this simple structure, a geometrical effect ensures a strong coupling between an embedded emitter and the optical mode of interest and a combination of tapers and mirrors a...

  7. Quantitative single-photon emission tomography for cerebral flow and receptor distribution imaging

    International Nuclear Information System (INIS)

    Budinger, T.F.

    1985-01-01

    Recently there has been renewed interest in single-photon emission tomography for two major reasons. First, correction methods have been devised for attenuation compensation, nonuniform resolution, and scattered radiation. Second, new radiopharmaceuticals with 1-5% uptake in the brain provide adequate statistics for quantitative imaging of flow using properly designed single-photon tomographic instruments. The lack of commercially available instruments designed specifically to optimize sensitivity for a resolution finer than 15 mm full width at half maximum (FWHM) seems now to be the major deterrent to the widespread use of single-photon emission tomography. But it appears now that some development in this respect also might lead to a widespread renewed interest in single-photon tomography of the brain. Major activities of the past few years can be placed in three distinct categories of instrumentation and methodology

  8. Tailoring light-sound interactions in a single mode fiber for the high-power transmission or sensing applications

    Science.gov (United States)

    Gulistan, Aamir; Rahman, M. M.; Ghosh, Souvik; Rahman, B. M. A.

    2018-03-01

    A full-vectorial numerically efficient Finite Element Method (FEM) based computer code is developed to study complex light-sound interactions in a single mode fiber (SMF). The SBS gain or SBS threshold in a fiber is highly related to the overlap between the optical and acoustic modes. For a typical SMF the acoustic-optic overlap strongly depends on the optical and acoustic mode profiles and it is observed that the acoustic mode is more confined in the core than the optical mode and reported overlap is around 94 % between these fundamental optical and acoustic modes. However, it is shown here that selective co-doping of Aluminum and Germanium in core reduces the acoustic index while keeping the optical index of the same value and thus results in increased acoustic- optic overlap of 99.7%. On the other hand, a design of acoustic anti-guide fiber for high-power transmission systems is also proposed, where the overlap between acoustic and optical modes is reduced. Here, we show that by keeping the optical properties same as a standard SMF and introducing a Boron doped 2nd layer in the cladding, a very low value of 2.7% overlap is achieved. Boron doping in cladding 2nd layer results in a high acoustic index and acoustic modes shifts in the cladding from the core, allowing much high power delivery through this SMF.

  9. MICROSTRUCTURING OF SILICON SINGLE CRYSTALS BY FIBER LASER IN HIGH-SPEED SCANNING MODE

    Directory of Open Access Journals (Sweden)

    T. A. Trifonova

    2015-11-01

    Full Text Available Subject of Study. The surface structure of the silicon wafers (substrate with a thermally grown silicon dioxide on the surface (of SiO2/Si is studied after irradiation by pulse fiber laser of ILI-1-20 type. The main requirements for exposure modes of the system are: the preservation of the integrity of the film of silicon dioxide in the process of microstructuring and the absence of interference of surrounding irradiated areas of the substrate. Method. Studies were carried out on silicon wafers KEF-4,5 oriented in the crystallographic plane (111 with the source (natural silicon dioxide (SiO2 with thickness of about 4 nm, and SiO2 with 40 nm and 150 nm thickness, grown by thermal oxidation in moist oxygen. Also, wafers KHB-10 oriented in the plane (100 with 500 nm thickness of thermal oxide were investigated. Irradiation of SiO2/Si system was produced by laser complex based on ytterbium fiber pulse laser ILI-1-20. Nominal output power of the laser was 20 W, and the laser wavelength was λ = 1062 nm. Irradiation was carried out by a focused beam spot with a diameter of 25 microns and a pulse repetition rate of 99 kHz. The samples with 150 nm and 40 nm thickness of SiO2 were irradiated at a power density equal to 1,2·102 W/cm2, and the samples of SiO2 with 500 nm thickness were irradiated at a power density equal to 2,0·102 W/cm2. Scanning was performed using a two-axis Coordinate Scanning Device based on VM2500+ drives with control via a PC with the software package "SinMarkTM." Only one scan line was used at the maximum speed of the beam equal to 8750 mm/s. Morphology control of the irradiated samples was conducted by an optical microscope ZeissA1M with high-resolution CCD array. A scanning probe microscope Nanoedicator of the NT-MDT company was used for structural measurements. Main Results. It has been shown that at a single exposure of high-frequency pulsed laser radiation on SiO2/Si system, with maintaining the integrity of the SiO2 film

  10. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    International Nuclear Information System (INIS)

    Knauer, J.P.; Verdon, C.P.; Meyerhofer, D.D.; Boehly, T.R.; Bradley, D.K.; Smalyuk, V.A.; Ofer, D.; McKenty, P.W.; Glendinning, S.G.; Kalantar, D.H.; Watt, R.G.; Gobby, P.L.; Willi, O.; Taylor, R.J.

    1997-01-01

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5x10 14 W/cm 2 . Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%endash 7% over a 600-μm-diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-μm and 60-μm wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-μm-thick polystyrene foam buffer layer resulted in reduced growth of the 31-μm perturbation and essentially unchanged growth for the 60-μm case when compared to targets without foam. copyright 1997 American Institute of Physics

  11. Capacitive deionization of arsenic-contaminated groundwater in a single-pass mode.

    Science.gov (United States)

    Fan, Chen-Shiuan; Liou, Sofia Ya Hsuan; Hou, Chia-Hung

    2017-10-01

    A single-pass-mode capacitive deionization (CDI) reactor was used to remove arsenic from groundwater in the presence of multiple ions. The CDI reactor involved an applied voltage of 1.2 V and six cell pairs of activated carbon electrodes, each of which was 20 × 30 cm 2 . The results indicate that this method achieved an effluent arsenic concentration of 0.03 mg L -1 , which is lower than the arsenic concentration standard for drinking water and irrigation sources in Taiwan, during the charging stage. Additionally, the ability of the CDI to remove other coexisting ions was studied. The presence of other ions has a significant influence on the removal of arsenic from groundwater. From the analysis of the electrosorption selectivity, the preference for anion removal could be ordered as follows: NO 3 -  > SO 4 2-  > F -  > Cl - >As. The electrosorption selectivity for cations could be ordered as follows: Ca 2+  > Mg 2+  > Na +  ∼ K + . Moreover, monovalent cations can be replaced by divalent cations at the electrode surface in the later period of the electrosorption stage. Consequently, activated carbon-based capacitive deionization is demonstrated to be a high-potential technology for remediation of arsenic-contaminated groundwater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Single-mode optical waveguides on native high-refractive-index substrates

    Directory of Open Access Journals (Sweden)

    Richard R. Grote

    2016-10-01

    Full Text Available High-refractive-index semiconductor optical waveguides form the basis for modern photonic integrated circuits (PICs. However, conventional methods for achieving optical confinement require a thick lower-refractive-index support layer that impedes large-scale co-integration with electronics and limits the materials on which PICs can be fabricated. To address this challenge, we present a general architecture for single-mode waveguides that confine light in a high-refractive-index material on a native substrate. The waveguide consists of a high-aspect-ratio fin of the guiding material surrounded by lower-refractive-index dielectrics and is compatible with standard top-down fabrication techniques. This letter describes a physically intuitive, semi-analytical, effective index model for designing fin waveguides, which is confirmed with fully vectorial numerical simulations. Design examples are presented for diamond and silicon at visible and telecommunications wavelengths, respectively, along with calculations of propagation loss due to bending, scattering, and substrate leakage. Potential methods of fabrication are also discussed. The proposed waveguide geometry allows PICs to be fabricated alongside silicon CMOS electronics on the same wafer, removes the need for heteroepitaxy in III-V PICs, and will enable wafer-scale photonic integration on emerging material platforms such as diamond and SiC.

  13. Experimental demonstration of single-mode fiber coupling over relatively strong turbulence with adaptive optics.

    Science.gov (United States)

    Chen, Mo; Liu, Chao; Xian, Hao

    2015-10-10

    High-speed free-space optical communication systems using fiber-optic components can greatly improve the stability of the system and simplify the structure. However, propagation through atmospheric turbulence degrades the spatial coherence of the signal beam and limits the single-mode fiber (SMF) coupling efficiency. In this paper, we analyze the influence of the atmospheric turbulence on the SMF coupling efficiency over various turbulences. The results show that the SMF coupling efficiency drops from 81% without phase distortion to 10% when phase root mean square value equals 0.3λ. The simulations of SMF coupling with adaptive optics (AO) indicate that it is inevitable to compensate the high-order aberrations for SMF coupling over relatively strong turbulence. The SMF coupling efficiency experiments, using an AO system with a 137-element deformable mirror and a Hartmann-Shack wavefront sensor, obtain average coupling efficiency increasing from 1.3% in open loop to 46.1% in closed loop under a relatively strong turbulence, D/r0=15.1.

  14. Role of third-order dispersion in chirped Airy pulse propagation in single-mode fibers

    Science.gov (United States)

    Cai, Wangyang; Wang, Lei; Wen, Shuangchun

    2018-04-01

    The dynamic propagation of the initial chirped Airy pulse in single-mode fibers is studied numerically, special attention being paid to the role of the third-order dispersion (TOD). It is shown that for the positive TOD, the Airy pulse experiences inversion irrespective of the sign of initial chirp. The role of TOD in the dynamic propagation of the initial chirped Airy pulse depends on the combined sign of the group-velocity dispersion (GVD) and the initial chirp. If the GVD and chirp have the opposite signs, the chirped Airy pulse compresses first and passes through a breakdown area, then reconstructs a new Airy pattern with opposite acceleration, with the breakdown area becoming small and the main peak of the new Airy pattern becoming asymmetric with an oscillatory structure due to the positive TOD. If the GVD and chirp have the same signs, the finite-energy Airy pulse compresses to a focal point and then inverses its acceleration, in the case of positive TOD, the distance to the focal point becoming smaller. At zero-dispersion point, the finite-energy Airy pulse inverses to the opposite acceleration at a focal point, with the tight-focusing effect being reduced by initial chirp. Under the effect of negative TOD, the initial chirped Airy pulse disperses and the lobes split. In addition, in the anomalous dispersion region, for strong nonlinearity, the initial chirped Airy pulse splits and enters a soliton shedding regime.

  15. Fidelity of Quantum Teleportation for Single-Mode Squeezed State Light

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-Xiang; XIE Chang-De; PENG Kun-Chi

    2005-01-01

    @@ The fidelity of quantum teleportation of a single-mode squeezed state of light is calculated based on the general theory of quantum-mechanical measurement in the Schrodinger picture. It is shown that the criterion for the nonclassical state teleportation is different from that for coherent state. F = 1/2 is no longer the rigorous boundary between classical and quantum teleportation for a squeezed state of light. When the quantum entanglement of an Einstein-Podolsky-Rosen (EPR) beam used for teleportation and the parameters of the system are given,the fidelity depends on the squeezing of the input squeezed state. The higher the squeezing is, the smaller the fidelity is, and the lower the classical limitation of fidelity is. The dependence of the optimum gain for teleporting a squeezed vacuum state upon the EPR entanglement is also calculated. The results obtained provide important references for designing experimental systems of teleporting a non-classical state and judging the quality of the teleported quantum state.

  16. Single Mode SU8 Polymer Based Mach-Zehnder Interferometer for Bio-Sensing Application

    Science.gov (United States)

    Boiragi, Indrajit; Kundu, Sushanta; Makkar, Roshan; Chalapathi, Krishnamurthy

    2011-10-01

    This paper explains the influence of different parameters to the sensitivity of an optical waveguide Mach-Zehnder Interferometer (MZI) for real time detection of biomolecules. The sensing principle is based on the interaction of evanescence field with the biomolecules that get immobilized on sensing arm. The sensitivity has been calculated by varying the sensing window length, wavelength and concentration of bio-analyte. The maximum attainable sensitivity for the preferred design is the order of 10-8 RIU at 840 nm wavelength with a sensing window length of 1cm. All the simulation work has been carried out with Opti-BPMCAD for the optimization of MZI device parameters. The SU8 polymers are used as a core and clad material to fabricate the waveguide. The refractive index of cladding layer is optimized by varying the curing temperature for a fixed time period and the achieved index difference between core and clad is Δn = 0.0151. The fabricated MZI device has been characterized with LASER beam profiler at 840 nm wavelength. This study demonstrates the effectiveness of the different parameter to the sensitivity of a single mode optical waveguide Mach-Zehnder Interferometer for bio-sensing application.

  17. Influence of photo- and thermal bleaching on pre-irradiation low water peak single mode fibers

    Science.gov (United States)

    Yin, Jianchong; Wen, Jianxiang; Luo, Wenyun; Xiao, Zhongyin; Chen, Zhenyi; Wang, Tingyun

    2011-12-01

    Reducing the radiation-induced transmission loss in low water peak single mode fiber (LWP SMF) has been investigated by using photo-bleaching method with 980nm pump light source and using thermal-bleaching method with temperature control system. The results show that the radiation-induced loss of pre-irradiation optical fiber can be reduced effectively with the help of photo-bleaching or thermal-bleaching. Although the effort of photo-bleaching is not as significant as thermal-bleaching, by using photo-bleaching method, the loss of fiber caused by radiation-induced defects can be reduced best up to 49% at 1310nm and 28% at 1550nm in low pre-irradiation condition, the coating of the fiber are not destroyed, and the rehabilitating time is just several hours, while self-annealing usually costs months' time. What's more, the typical high power LASER for photo-bleaching can be 980nm pump Laser Diode, which is very accessible.

  18. Pulsed x-ray induced attenuation measurements of single mode optical fibers and coupler materials

    International Nuclear Information System (INIS)

    Johan, A.; Charre, P.

    1994-01-01

    Pulsed X-ray induced transient radiation attenuation measurements of single mode optical fibers have been performed versus total dose, light wavelength, optical power and fiber coil diameter in order to determine the behavior of parameters sensitive to ionizing radiation. The results did not show any photobleaching phenomenon and the attenuation was found independent of the spool diameter. As expected, transient attenuation was lower for higher wave-lengths. The recovery took place in the millisecond range and was independent of total dose, light wavelength and optical power. In optical modules and devices a large range of behaviors was observed according to coupler material i.e., Corning coupler showed a small peak attenuation that remained more than one day later; on the other hand LiTaO 3 material experienced an order of magnitude higher peak attenuation and a recovery in the millisecond range. For applications with optical fibers and integrated optics devices the authors showed that in many cases the optical fiber (length above 100 m) is the most sensitive device in a transient ionizing radiation field

  19. Single-mode, All-Solid-State Nd:YAG Laser Pumped UV Converter

    Science.gov (United States)

    Prasad, Narasimha S.; Armstrong, Darrell, J.; Edwards, William C.; Singh, Upendra N.

    2008-01-01

    In this paper, the status of a high-energy, all solid-state Nd:YAG laser pumped nonlinear optics based UV converter development is discussed. The high-energy UV transmitter technology is being developed for ozone sensing applications from space based platforms using differential lidar technique. The goal is to generate greater than 200 mJ/pulse with 10-50 Hz PRF at wavelengths of 308 nm and 320 nm. A diode-pumped, all-solid-state and single longitudinal mode Nd:YAG laser designed to provide conductively cooled operation at 1064 nm has been built and tested. Currently, this pump laser provides an output pulse energy of >1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns with an electrical-to-optical system efficiency of greater than 7% and a M(sup 2) value of UV converter arrangement basically consists of an IR Optical Parametric Oscillator (OPO) and a Sum Frequency Generator (SFG) setups that are pumped by 532 nm wavelength obtained via Second Harmonic Generation (SHG). In this paper, the operation of an inter cavity SFG with CW laser seeding scheme generating 320 nm wavelength is presented. Efforts are underway to improve conversion efficiency of this mJ class UV converter by modifying the spatial beam profile of the pump laser.

  20. A Novel Technique for Sterilization Using a Power Self-Regulated Single-Mode Microwave Cavity.

    Science.gov (United States)

    Reverte-Ors, Juan D; Pedreño-Molina, Juan L; Fernández, Pablo S; Lozano-Guerrero, Antonio J; Periago, Paula M; Díaz-Morcillo, Alejandro

    2017-06-07

    In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs) for different food samples (laboratory medium, soup, or fish-based animal by-products). The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.

  1. A Novel Technique for Sterilization Using a Power Self-Regulated Single-Mode Microwave Cavity

    Directory of Open Access Journals (Sweden)

    Juan D. Reverte-Ors

    2017-06-01

    Full Text Available In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs for different food samples (laboratory medium, soup, or fish-based animal by-products. The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.

  2. Bending , Heating and Pressure Effects of He-Ne Laserin Single Mode Fiber

    Directory of Open Access Journals (Sweden)

    Nizar Salim Shnan

    2017-12-01

    Full Text Available In this paper a single mode fiber have been chosen with a refractive index (1.50 to the core, and (1.485 to the cladding, with length of (2 m. It was exposed this optical fiber to a bending with different diameters, and to a different temperatures as well as pressure due to putting different weights to study dispersion phenomenon which affects on a pulse shape that travels in optical fiber. Experimental results explain when a bending diameter for an optical fiber increases it will decrease the dispersion and pulse shape will approximate from a Gaussian shape , and the increasing in temperature will increasing  the attenuation in the pulse transfer through the optical fiber .                                                                                                 But when increasing pressure, the dispersion will increases and the pulse shape will be distorted

  3. Imaging of the dopaminergic neurotransmission system using single-photon emission tomography and positron emission tomography in patients with parkinsonism

    International Nuclear Information System (INIS)

    Booij, J.; Tissingh, G.; Winogrodzka, A.; Royen, E.A. van

    1999-01-01

    Parkinsonism is a feature of a number of neurodegenerative diseases, including Parkinson's disease, multiple system atrophy and progressive supranuclear palsy. The results of post-mortem studies point to dysfunction of the dopaminergic neurotransmitter system in patients with parkinsonism. Nowadays, by using single-photon emission tomography (SPET) and positron emission tomography (PET) it is possible to visualise both the nigrostriatal dopaminergic neurons and the striatal dopamine D 2 receptors in vivo. Consequently, SPET and PET imaging of elements of the dopaminergic system can play an important role in the diagnosis of several parkinsonian syndromes. This review concentrates on findings of SPET and PET studies of the dopaminergic neurotransmitter system in various parkinsonian syndromes. (orig.)

  4. Acoustic emission evolution during sliding friction of Hadfield steel single crystal

    Science.gov (United States)

    Lychagin, D. V.; Novitskaya, O. S.; Kolubaev, A. V.; Sizova, O. V.

    2017-12-01

    Friction is a complex dynamic process. Direct observation of processes occurring in the friction zone is impossible due to a small size of a real contact area and, as a consequence, requires various additional methods applicable to monitor a tribological contact state. One of such methods consists in the analysis of acoustic emission data of a tribological contact. The use of acoustic emission entails the problem of interpreting physical sources of signals. In this paper, we analyze the evolution of acoustic emission signal frames in friction of Hadfield steel single crystals. The chosen crystallographic orientation of single crystals enables to identify four stages related to friction development as well as acoustic emission signals inherent in these stages. Acoustic emission signal parameters are studied in more detail by the short-time Fourier transform used to determine the time variation of the median frequency and its power spectrum. The results obtained will facilitate the development of a more precise method to monitor the tribological contact based on the acoustic emission method.

  5. Saline-enhanced hepatic radiofrequency ablation using a perfused-cooled electrode: comparison of dual probe bipolar mode with monopolar and single probe bipolar modes

    International Nuclear Information System (INIS)

    Lee, Jeong Min; Han, Joon Koo; Kim, Se Hyung; Lee, Jae Young; Kim, Dae Jin; Lee, Min Woo; Cho, Gyung Goo; Han, Chang Jin; Choi, Byung Ihn

    2004-01-01

    To determine whether saline-enhanced dual probe bipolar radiofrequency ablation (RFA) using perfused-cooled electrodes shows better in-vitro efficiency than monopolar or single probe bipolar RFA in creating larger coagulation necrosis. RF was applied to excised bovine livers in both bipolar and monopolar modes using a 200W generator (CC-3; Radionics) and the perfused-cooled electrodes for 10 mins. After placing single or double perfused-cooled electrodes in the explanted liver, 30 ablation zones were created at three different regimens: group A; saline-enhanced monopolar RFA, group B; saline-enhanced single probe bipolar RFA, and group C; saline-enhanced dual probe bipolar RFA. During RFA, we measured the tissue temperature at 15mm from the electrode. The dimensions of the ablation zones and changes in the impedance currents and liver temperature during RFA were then compared between the groups. The mean current values were higher for monopolar mode (group A) than for the bipolar modes (group B and C): 1550 ± 25 mA in group A, 764 ±189 mA in group B and 819 ± 98 mA in group C(ρ 3 in group A, 23.7 ±3.8 cm 3 in group B, and 34.2 ± 5.1 cm 3 in group C(ρ 0.05). The temperature at 15 mm from the electrode was higher in group C than in the other groups: 70 ± 18 .deg. C in group A, 59 ± 23 .deg. C in group B and 96 ± 16 .deg. C in group C (ρ < 0.05). Saline-enhanced bipolar RFA using dual perfused-cooled electrodes increases the dimension of the ablation zone more efficiently than monopolar RFA or single probe bipolar RFA

  6. Characteristics of a single photon emission tomography system with a wide field gamma camera

    International Nuclear Information System (INIS)

    Mathonnat, F.; Soussaline, F.; Todd-Pokropek, A.E.; Kellershohn, C.

    1979-01-01

    This text summarizes a work study describing the imagery possibilities of a single photon emission tomography system composed of a conventional wide field gamma camera, connected to a computer. The encouraging results achieved on the various phantoms studied suggest a significant development of this technique in clinical work in Nuclear Medicine Departments [fr

  7. Relative work function of clean molybdenum single-crystal planes determined by field emission microscopy

    International Nuclear Information System (INIS)

    Bergeret, G.; Abon, M.; Tardy, B.; Teichner, S.J.

    1974-01-01

    A probe-hole field emission microscope was used to determine the work function of clean molybdenum single crystal planes relative to the average work function of the field emitter, assumed to be 4.20 eV. Results are compared with other available data

  8. Single-mode Brillouin fiber laser passively stabilized at resonance frequency with self-injection locked pump laser

    International Nuclear Information System (INIS)

    Spirin, V V; Lopez-Mercado, C A; Megret, P; Fotiadi, A A

    2012-01-01

    We demonstrate a single-mode Brillouin fiber ring laser, which is passively stabilized at pump resonance frequency by using self-injection locking of semiconductor pump laser. Resonance condition for Stokes radiation is achieved by length fitting of Brillouin laser cavity. The laser generate single-frequency Stokes wave with linewidth less than 0.5 kHz using approximately 17-m length cavity

  9. Fingerprinting of traditional Chinese medicines on the C18-Diol mixed-mode column in online or offline two-dimensional liquid chromatography on the single column modes.

    Science.gov (United States)

    Wang, Qing; Tong, Ling; Yao, Lin; Zhang, Peng; Xu, Li

    2016-06-05

    In the present study, a mixed-mode stationary phase, C18-Diol, was applied for fingerprint analysis of traditional Chinese medicines. Hydrophobic, hydrogen bonding and electrostatic interactions were demonstrated to contribute the retention separately or jointly, which endowed the C18-Diol stationary phase with distinct selectivity compared to the bare C18 one. The separation of total alkaloids extracted from Fritillaria hupehensis was compared on the C18-Diol and conventional C18 column with the greater resolving power and better symmetry responses on the former one. Besides, a novel two-dimensional liquid chromatography on the single column (2D-LC-1C) was realized on C18-Diol with the offline mode for the alcohol extract of Fritillaria hupehensis and online mode for Ligusticum chuanxiong Hort. The early co-eluted extracted components with great polarity on the first dimension were reinjected on the same column and well separated on the second dimension. The results exhibited that the two complementary RPLC and HILIC modes on C18-Diol stationary phase enhanced the separation capacity and revealed more abundant chemical information of the sample, which was a powerful tool in analyzing complex herbal medicines. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Ag-protein plasmonic architectures for surface plasmon-coupled emission enhancements and Fabry-Perot mode-coupled directional fluorescence emission

    Science.gov (United States)

    Badiya, Pradeep Kumar; Patnaik, Sai Gourang; Srinivasan, Venkatesh; Reddy, Narendra; Manohar, Chelli Sai; Vedarajan, Raman; Mastumi, Noriyoshi; Belliraj, Siva Kumar; Ramamurthy, Sai Sathish

    2017-10-01

    We report the use of silver decorated plant proteins as spacer material for augmented surface plasmon-coupled emission (120-fold enhancement) and plasmon-enhanced Raman scattering. We extracted several proteins from different plant sources [Triticum aestivum (TA), Aegle marmelos (AM), Ricinus communis (RC), Jatropha curcas (JC) and Simarouba glauca (SG)] followed by evaluation of their optical properties and simulations to rationalize observed surface plasmon resonance. Since the properties exhibited by protein thin films is currently gaining research interest, we have also carried out simulation studies with Ag-protein biocomposites as spacer materials in metal-dielectric-metal planar microcavity architecture for guided emission of Fabry-Perot mode-coupled fluorescence.

  11. Characterization of microwave plasma in a multicusp using 2D emission based tomography: Bessel modes and wave absorption

    Science.gov (United States)

    Rathore, Kavita; Bhattacharjee, Sudeep; Munshi, Prabhat

    2017-06-01

    A tomographic method based on the Fourier transform is used for characterizing a microwave plasma in a multicusp (MC), in order to obtain 2D distribution of plasma emissions, plasma (electron) density (Ne) and temperature (Te). The microwave plasma in the MC is characterized as a function of microwave power, gas pressure, and axial distance. The experimentally obtained 2D emission profiles show that the plasma emissions are generated in a circular ring shape. There are usually two bright rings, one at the plasma core and another near the boundary. The experimental results are validated using a numerical code that solves Maxwell's equations inside a waveguide filled with a plasma in a magnetic field, with collisions included. It is inferred that the dark and bright circular ring patterns are a result of superposition of Bessel modes (TE11 and TE21) of the wave electric field inside the plasma filled MC, which are in reasonable agreement with the plasma emission profiles. The tomographically obtained Ne and Te profiles indicate higher densities in the plasma core (˜1010 cm-3) and enhanced electron temperature in the ECR region (˜13 eV), which are in agreement with earlier results using a Langmuir probe and optical emission spectroscopy (OES) diagnostics.

  12. Tailoring surface plasmon resonance and dipole cavity plasmon modes of scattering cross section spectra on the single solid-gold/gold-shell nanorod

    International Nuclear Information System (INIS)

    Chou Chau, Yuan-Fong; Lim, Chee Ming; Kumara, N. T. R. N.; Yoong, Voo Nyuk; Lee, Chuanyo; Huang, Hung Ji; Lin, Chun-Ting; Chiang, Hai-Pang

    2016-01-01

    Tunable surface plasmon resonance (SPR) and dipole cavity plasmon modes of the scattering cross section (SCS) spectra on the single solid-gold/gold-shell nanorod have been numerically investigated by using the finite element method. Various effects, such as the influence of SCS spectra under x- and y-polarizations on the surface of the single solid-gold/gold-shell nanorod, are discussed in detail. With the single gold-shell nanorod, one can independently tune the relative SCS spectrum width by controlling the rod length and rod diameter, and the surface scattering by varying the shell thickness and polarization direction, as well as the dipole peak energy. These behaviors are consistent with the properties of localized SPRs and offer a way to optically control and produce selected emission wavelengths from the single solid-gold/gold-shell nanorod. The electric field and magnetic distributions provide us a qualitative idea of the geometrical properties of the single solid-gold/gold-shell nanorod on plasmon resonance.

  13. Tunable single-polarization single-longitudinal-mode erbium-doped fiber ring laser employing a CMFBG filter and saturable absorber

    Science.gov (United States)

    Feng, Suchun; Lu, Shaohua; Peng, Wanjing; Li, Qi; Feng, Ting; Jian, Shuisheng

    2013-04-01

    A tunable single-polarization single-longitudinal-mode (SLM) erbium-doped fiber ring laser is proposed and demonstrated. For the first time as we know, a chirped moiré fiber Bragg grating (CMFBG) filter with ultra-narrow transmission band and a uniform fiber Bragg grating (UFBG) are used to select the laser longitudinal mode. The stable SLM operation of the fiber laser is guaranteed by the combination of the CMFBG filter and 3 m unpumped erbium-doped fiber acting as a saturable absorber. The single polarization operation of the fiber laser is obtained by using an inline broadband polarizer. A tuning range of about 0.7 nm with about 0.1 nm step is achieved by stretching the uniform FBG.

  14. Efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser.

    Science.gov (United States)

    Wang, P; Cooper, L J; Sahu, J K; Clarkson, W A

    2006-01-15

    A novel approach to achieving robust single-spatial-mode operation of cladding-pumped fiber lasers with multimode cores is reported. The approach is based on the use of a fiber geometry in which the core has a helical trajectory within the inner cladding to suppress laser oscillation on higher-order modes. In a preliminary proof-of-principle study, efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser with a 30 microm diameter core and a numerical aperture of 0.087 has been demonstrated. The laser yielded 60.4 W of output at 1043 nm in a beam with M2 clad fiber lasers.

  15. Study on performance and emission characteristics of a single cylinder diesel engine using exhaust gas recirculation

    Directory of Open Access Journals (Sweden)

    Anantha Raman Lakshmipathi

    2017-01-01

    Full Text Available Exhaust gas re-circulation is a method used in compression ignition engines to control and reduce NOx emission. These emissions are controlled by reducing the oxygen concentration inside the cylinder and thereby reducing the flame temperature of the charge mixture inside the combustion chamber. In the present investigation, experiments were performed to study the effect of exhaust gas re-circulation on performance and emission characteristics in a four stroke single cylinder, water cooled and constant speed diesel engine. The experiments were performed to study the performance and emissions for different exhaust gas re-circulation ratios of the engine. Performance parameters such as brake thermal efficiency, indicated thermal efficiency, specific fuel consumption, total fuel consumption and emission parameters such as oxides of nitrogen, unburned hydrocarbons, carbon monoxide, carbon dioxide and smoke opacity were measured. Reductions in NOx and CO2 were observed but other emissions like HC, CO, and smoke opacity were found to have increased with the usage of exhaust gas re-circulation. The 15% exhaust gas re-circulation was found optimum for the engine in the aspects of performance and emission.

  16. Dissociation pathways of a single dimethyl disulfide on Cu(111): Reaction induced by simultaneous excitation of two vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Motobayashi, Kenta, E-mail: kmotobayashi@cat.hokudai.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan); Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Kim, Yousoo [Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Arafune, Ryuichi [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Ohara, Michiaki; Ueba, Hiromu; Kawai, Maki, E-mail: maki@k.u-tokyo.ac.jp [Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan)

    2014-05-21

    We present a novel reaction mechanism for a single adsorbed molecule that proceeds via simultaneous excitation of two different vibrational modes excited by inelastic tunneling electrons from a scanning tunneling microscope. Specifically, we analyze the dissociation of a single dimethyl disulfide (DMDS, (CH{sub 3}S){sub 2}) molecule on Cu(111) by using a versatile theoretical method, which permits us to simulate reaction rates as a function of sample bias voltage. The reaction is induced by the excitation of C-H stretch and S-S stretch modes by a two-electron process at low positive bias voltages. However, at increased voltages, the dissociation becomes a single-electron process that excites a combination mode of these stretches, where excitation of the C-H stretch is the energy source and excitation of the S-S stretch mode enhances the anharmonic coupling rate. A much smaller dissociation yield (few orders of magnitude) at negative bias voltages is understood in terms of the projected density of states of a single DMDS on Cu(111), which reflects resonant excitation through the molecular orbitals.

  17. Open quantum systems and the two-level atom interacting with a single mode of the electromagnetic field

    International Nuclear Information System (INIS)

    Sandulescu, A.; Stefanescu, E.

    1987-07-01

    On the basis of Lindblad theory of open quantum systems we obtain new optical equations for the system of two-level atom interacting with a single mode of the electromagnetic field. The conventional Block equations in a generalized form with field phases are obtained in the hypothesis that all the terms are slowly varying in the rotating frame.(authors)

  18. Single-Mode, High Repetition Rate, Compact Ho:YLF Laser for Space-Borne Lidar Applications

    Science.gov (United States)

    Bai, Yingxin; Yu, Jirong; Wong, Teh-Hwa; Chen, Songsheng; Petros, Mulugeta; Singh, Upendra N.

    2014-01-01

    A single transverse/longitudinal mode, compact Q-switched Ho:YLF laser has been designed and demonstrated for space-borne lidar applications. The pulse energy is between 34-40 mJ for 100-200 Hz operation. The corresponding peak power is >1 MW.

  19. Light coupling and distribution for Si3N4/SiO2 integrated multichannel single-mode sensing system

    Science.gov (United States)

    Kaźmierczak, Andrzej; Dortu, Fabian; Schrevens, Olivier; Giannone, Domenico; Bouville, David; Cassan, Eric; Gylfason, Kristinn B.; Sohlström, Hans; Sanchez, Benito; Griol, Amadeu; Hill, Daniel

    2009-01-01

    We present an efficient and highly alignment-tolerant light coupling and distribution system for a multichannel Si3N4/SiO2 single-mode photonics sensing chip. The design of the input and output couplers and the distribution splitters is discussed. Examples of multichannel data obtained with the system are given.

  20. Mode I crack analysis in single crystals with anisotropic discrete dislocation plasticity : I. Formulation and crack growth

    NARCIS (Netherlands)

    Shishvan, Siamak Soleymani; Van der Giessen, Erik

    Analyses of monotonic loading of a plane-strain mode I crack in an fcc single crystal under small-scale yielding are carried out using discrete dislocation plasticity (DDP) incorporating anisotropic elasticity. Two crystallographically symmetric crack orientations are considered where plane-strain

  1. Tunable and stable single-longitudinal-mode dual-wavelength erbium fiber laser with 1.3 nm mode spacing output

    International Nuclear Information System (INIS)

    Yeh, C H; Shih, F Y; Wang, C H; Chow, C W; Chi, S

    2008-01-01

    In this investigation, we propose and investigate a stable and tunable dual-wavelength erbium-doped fiber (EDF) ring laser with self-injected Fabry-Perot laser diode (FP-LD) scheme. By using an FP-LD incorporated with a tunable bandpass filter (TBF) within the gain cavity, the fiber laser can lase at two single-longitudinal-mode (SLM) wavelengths simultaneously due to the self-injected operation. The proposed dual-wavelength laser has a good performance of the output power and optical side-mode suppression ratio (SMSR). The laser also shows a wide tuning range from 1523.08 to 1562.26 nm. Besides, the output stabilities of the fiber laser are also discussed

  2. Realization of Current Mode Universal Filter and a Dual-Mode Single Resistance Controlled Quadrature Oscillator Employing VDCC and Only Grounded Passive Elements

    Directory of Open Access Journals (Sweden)

    Manish Gupta

    2017-01-01

    Full Text Available The manuscript presents a circuit that can act as a universal filter as well as a single resistence controlled oscillator by unpretentiously changing the switch positions. The circuit employs only two active devices and all grounded passive elements. The utilization of only grounded passive components makes this circuit a better choice for integrated circuit implementation. The current mode biquadratic filter offers all the five basic responses along with independent tunability of its quality factor. The dual-mode quadrature sinusoidal oscillator offers explicit current outputs along with voltage outputs. The circuit also offers a simple and uncoupled condition of oscillation and frequency of oscillation. The typical analysis such as non-ideal, sensitivity and parasitic analysis along with the regular simulation results as well as experimental results are exposed here, to strengthen the design idea.

  3. National emission standards for hazardous air pollutants application for approval to construct rotary mode core-sampling truck and exhauster

    International Nuclear Information System (INIS)

    1993-05-01

    Characterization of wastes in the underground single-shell tanks and double-shell tanks on the Hanford Site is crucial in developing the final disposal options for the waste and closure strategy for the Hanford Site. Additionally, characterization of tank waste is important for the waste tank safety programs. The Hanford Federal Facility Agreement and Consent Order (also referred to as the Tri-Party Agreement) Milestone M-10-00 requires the obtaining and analyzing of at least two samples from each single-shell tank, and Milestone M-10-13 specifically requires the ability to sample hard saltcake. Existing equipment does not allow sampling of all single-shell tanks within established tank safety limits. Consequently, the US Department of Energy, Richland Operations Office has developed a rotary mode core-sampling system that uses nitrogen gas to cool and clear the drill bit. A rotary mode core-sampling truck will be used on approximately 80 single-shell tanks which contain saltcake wastes, and will provide crucial information on the contents of the tanks. This application is a request for approval to construct and operate the rotary mode core-sampling truck and exhauster in the 200 East and 200 West Area Tank Farms of the Hanford Site. This request is being made pursuant to 40 CFR 61, Subpart H

  4. Phosphorus-free mode-locked semiconductor laser with emission wavelength 1550 nm

    Science.gov (United States)

    Kolodeznyi, E. S.; Novikov, I. I.; Babichev, A. V.; Kurochkin, A. S.; Gladyshev, A. G.; Karachinsky, L. Ya; Gadzhiev, I. M.; Buyalo, M. S.; Usikova, A. A.; Ilynskaya, N. D.; Bougrov, V. E.; Egorov, A. Yu

    2017-11-01

    We have fabricated passive mode-locked laser diodes based on strained InGaAlAs/InGaAs/InP heterostructures with crystal lattice mismatch parameter of +1.0 % between quantum well and barrier. The laser with temperature stabilization at 18 °C was demonstrated 10.027 GHz optical pulse repetition rate with 6 ps pulse duration time. Timing jitter of optical pulses in mode-locked regime was 0.145 ps.

  5. Self-similar photonic crystal cavity with ultrasmall mode volume for single-photon nonlinearities

    DEFF Research Database (Denmark)

    Choi, Hyeongrak; Heuck, Mikkel; Englund, Dirk

    2017-01-01

    We propose a photonic crystal cavity design with self-similar structure to achieve ultrasmall mode volume. We describe the concept with a silicon-air nanobeam cavity at λ ∼ 1550nm, reaching a mode volume of ∼ 7.01 × 10∼5λ3.......We propose a photonic crystal cavity design with self-similar structure to achieve ultrasmall mode volume. We describe the concept with a silicon-air nanobeam cavity at λ ∼ 1550nm, reaching a mode volume of ∼ 7.01 × 10∼5λ3....

  6. A method to synchronize signals from multiple patient monitoring devices through a single input channel for inclusion in list-mode acquisitions

    International Nuclear Information System (INIS)

    O’Connor, J. Michael; Pretorius, P. Hendrik; Johnson, Karen; King, Michael A.

    2013-01-01

    Purpose: This technical note documents a method that the authors developed for combining a signal to synchronize a patient-monitoring device with a second physiological signal for inclusion into list-mode acquisition. Our specific application requires synchronizing an external patient motion-tracking system with a medical imaging system by multiplexing the tracking input with the ECG input. The authors believe that their methodology can be adapted for use in a variety of medical imaging modalities including single photon emission computed tomography (SPECT) and positron emission tomography (PET). Methods: The authors insert a unique pulse sequence into a single physiological input channel. This sequence is then recorded in the list-mode acquisition along with the R-wave pulse used for ECG gating. The specific form of our pulse sequence allows for recognition of the time point being synchronized even when portions of the pulse sequence are lost due to collisions with R-wave pulses. This was achieved by altering our software used in binning the list-mode data to recognize even a portion of our pulse sequence. Limitations on heart rates at which our pulse sequence could be reliably detected were investigated by simulating the mixing of the two signals as a function of heart rate and time point during the cardiac cycle at which our pulse sequence is mixed with the cardiac signal. Results: The authors have successfully achieved accurate temporal synchronization of our motion-tracking system with acquisition of SPECT projections used in 17 recent clinical research cases. In our simulation analysis the authors determined that synchronization to enable compensation for body and respiratory motion could be achieved for heart rates up to 125 beats-per-minute (bpm). Conclusions: Synchronization of list-mode acquisition with external patient monitoring devices such as those employed in motion-tracking can reliably be achieved using a simple method that can be implemented using

  7. A method to synchronize signals from multiple patient monitoring devices through a single input channel for inclusion in list-mode acquisitions

    Energy Technology Data Exchange (ETDEWEB)

    O’Connor, J. Michael; Pretorius, P. Hendrik; Johnson, Karen; King, Michael A., E-mail: Michael.King@umassmed.edu [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States)

    2013-12-15

    Purpose: This technical note documents a method that the authors developed for combining a signal to synchronize a patient-monitoring device with a second physiological signal for inclusion into list-mode acquisition. Our specific application requires synchronizing an external patient motion-tracking system with a medical imaging system by multiplexing the tracking input with the ECG input. The authors believe that their methodology can be adapted for use in a variety of medical imaging modalities including single photon emission computed tomography (SPECT) and positron emission tomography (PET). Methods: The authors insert a unique pulse sequence into a single physiological input channel. This sequence is then recorded in the list-mode acquisition along with the R-wave pulse used for ECG gating. The specific form of our pulse sequence allows for recognition of the time point being synchronized even when portions of the pulse sequence are lost due to collisions with R-wave pulses. This was achieved by altering our software used in binning the list-mode data to recognize even a portion of our pulse sequence. Limitations on heart rates at which our pulse sequence could be reliably detected were investigated by simulating the mixing of the two signals as a function of heart rate and time point during the cardiac cycle at which our pulse sequence is mixed with the cardiac signal. Results: The authors have successfully achieved accurate temporal synchronization of our motion-tracking system with acquisition of SPECT projections used in 17 recent clinical research cases. In our simulation analysis the authors determined that synchronization to enable compensation for body and respiratory motion could be achieved for heart rates up to 125 beats-per-minute (bpm). Conclusions: Synchronization of list-mode acquisition with external patient monitoring devices such as those employed in motion-tracking can reliably be achieved using a simple method that can be implemented using

  8. Physics of reshock and mixing in single-mode Richtmyer-Meshkov instability

    International Nuclear Information System (INIS)

    Schilling, O; Latini, M; Don, W

    2006-01-01

    The ninth-order weighted essentially non-oscillatory (WENO) shock-capturing method is used to investigate the physics of reshock and mixing in two-dimensional single-mode Richtmyer-Meshkov instability to late times. The initial conditions and computational domain were adapted from the Mach 1.21 air(acetone)/SF 6 shock tube experiment of Collins and Jacobs [J. Fluid Mech. 464, 113 (2002)]: the growth of the bubble and spike perturbation amplitudes from fifth- and ninth-order WENO simulations of this experiment were compared to the predictions of amplitude growth models, and were shown to be in very good agreement with the experimental data prior to reshock [Latini, Schilling and Don, Phys. Fluids (2007), in press]. In the present investigation, the density, vorticity, baroclinic vorticity production, and simulated density Schlieren fields are first presented to qualitatively describe reshock. The baroclinic circulation deposition on the interface is shown to agree with the predictions of the Samtaney and Zabusky [J. Fluid Mech. 269, 45 (1994)] model and linear instability theory. The time-evolution of the positive and negative circulation on the interface is considered before and after reshock: it is shown that the circulations are equal before, as well as after reshock, until the interaction of the reflected rarefaction with the layer leads to flow symmetry breaking and different evolutions of the positive and negative circulation. The post-reshock mixing layer growth is shown to be in very good agreement with three models predicting linear growth for a short time following reshock. Next, a comprehensive investigation of local and global mixing properties as a function of time is performed. The distribution and amount of mixed fluid along the shock propagation direction is characterized using averaged mole fraction profiles, a fast kinetic reaction model, and molecular mixing fractions. The modal distribution of energy in the mixing layer is quantified using the

  9. ESTABLISHED MODES AND STATIC CHARACTERISTICS OF THREE-PHASE ASYNCHRONOUS MOTOR POWERED WITH SINGLE PHASE NETWORK

    Directory of Open Access Journals (Sweden)

    V. S. Malyar

    2016-01-01

    Full Text Available A mathematical model is developed to study the operation of three-phase asynchronous motor with squirrel-cage rotor when the stator winding is powered from a single phase network. To create a rotating magnetic field one of the phases is fed through the capacitor. Due to the asymmetry of power feed not only transients, but the steady-state regimes are dynamic, so they are described by differential equations in any coordinate system. Their study cannot be carried out with sufficient adequacy on the basis of known equivalent circuits and require the use of dynamic parameters. In the mathematical model the state equations of the circuits of the stator and rotor are composed in the stationary three phase coordinate system. Calculation of the established mode is performed by solving the boundary problem that makes it possible to obtain the coordinate dependences over the period, without calculation of the transient process. In order to perform it, the original nonlinear differential equations are algebraized by approximating the variables with the use of cubic splines. The resulting nonlinear system of algebraic equations is a discrete analogue of the initial system of differential equations. It is solved by parameter continuation method. To calculate the static characteristics as a function of a certain variable, the system is analytically differentiated, and then numerically integrated over this variable. In the process of integration, Newton's refinement is performed at each step or at every few steps, making it possible to implement the integration in just a few steps using Euler's method. Jacobi matrices in both cases are the same. To account for the current displacement in the rods of the squirrel-cage rotor, each of them, along with the squirrel-cage rings, is divided in height into several elements. This results in several squirrel-cage rotor windings which are represented by three-phase windings with magnetic coupling between them.

  10. A comparative study of the single-mode Richtmyer-Meshkov instability

    Science.gov (United States)

    Bai, X.; Deng, X.-L.; Jiang, L.

    2017-11-01

    In this work, the single-mode Richtmyer-Meshkov instability is studied numerically to find a reasonable nonlinear theoretical model which can be applied to predict the interface evolution from the linear stage to the early nonlinear stage. The cut-cell-based sharp-interface methods MuSiC+ (Chang et al. in J Comput Phys 242:946-990, 2013) and CCGF (Bai and Deng in Adv Appl Math Mech 9(5):1052-1075, 2017) are applied to generate numerical results for comparisons. Classical Air-SF6 and Air-Helium conditions are applied in this study, and initial amplitude and Atwood number are varied for comparison. Comparisons to the simulation results from the literature show the applicability of MuSiC+ and CCGF. Comparisons to the nonlinear theoretical models show that ZS (Zhang and Sohn in Phys Lett A 212:149-155, 1996; Phys Fluids 9:1106-1124, 1997), SEA (Sadot et al. in Phys Rev Lett 80:1654-1657, 1998), and DR (Dimonte and Ramaprabhu in Phys Fluids 22:014104, 2010) models are valid for both spike and bubble growth rates, and MIK (Mikaelian in Phys Rev E 67:026319, 2003) and ZG (Zhang and Guo in J Fluid Mech 786:47-61, 2016) models are valid for bubble growth rate, when the initial perturbation is small and the Atwood number is low, but only the DR model is applicable for both spike and bubble growth rates when the initial perturbation amplitude and the Atwood number are large. A new term of non-dimensional initial perturbation amplitude is presented and multiplied to the DR model to get a unified fitted DR model, which gives consistent results to the simulation ones for small and large initial amplitudes.

  11. Model of a single mode energy harvester and properties for optimal power generation

    International Nuclear Information System (INIS)

    Liao Yabin; Sodano, Henry A

    2008-01-01

    The process of acquiring the energy surrounding a system and converting it into usable electrical energy is termed power harvesting. In the last few years, the field of power harvesting has experienced significant growth due to the ever increasing desire to produce portable and wireless electronics with extended life. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their finite energy supply, which necessitates their periodic replacement. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of disposable nature to allow the device to function over extended periods of time. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and covert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. The development of energy harvesting systems is greatly facilitated by an accurate model to assist in the design of the system. This paper will describe a theoretical model of a piezoelectric based energy harvesting system that is simple to apply yet provides an accurate prediction of the power generated around a single mode of vibration. Furthermore, this model will allow optimization of system parameters to be studied such that maximal performance can be achieved. Using this model an expression for the optimal resistance and a parameter describing the energy harvesting efficiency will be presented and evaluated through numerical simulations. The second part of this paper will present an experimental validation of the model and optimal parameters

  12. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    International Nuclear Information System (INIS)

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10 14 W/cm 2 . Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 μm diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 μm wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics

  13. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    Energy Technology Data Exchange (ETDEWEB)

    Knauer, J. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Betti, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Bradley, D. K. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Boehly, T. R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Collins, T. J. B. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Goncharov, V. N. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); McKenty, P. W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Smalyuk, V. A. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Verdon, C. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] (and others)

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 {mu}m diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 {mu}m wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics.

  14. Toward photostable multiplex analyte detection on a single mode planar optical waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Harshini [Los Alamos National Laboratory; Xei, Hongshi [Los Alamos National Laboratory; Anderson, Aaron S [Los Alamos National Laboratory; Grace, Wynne K [Los Alamos National Laboratory; Martinez, Jennifer S [NON LANL; Swanson, Basil [Los Alamos National Laboratory

    2009-01-01

    We have developed a waveguide-based optical biosensor for the sensitive and specific detection of biomarkers associated with disease. Our technology combines the superior optical properties of single-mode planar waveguides, the robust nature of functionalized self-assembled monolayer sensing films and the specificity of fluorescence sandwich immunoassays to detect biomarkers in complex biological samples such as serum, urine and sputum. We have previously reported the adaptation of our technology to the detection of biomarkers associated with breast cancer and anthrax. However, these approaches primarily used phospholipid bilayers as the functional film and organic dyes (ex: AlexaFluors) as the fluorescence reporter. Organic dyes are easily photodegraded and are not amenable to multiplexing because of their narrow Stokes' shift. Here we have developed strategies for conjugation of the detector antibodies with quantum dots for use in a multiplex detection platform. We have previously evaluated dihydroxylipoic acid quantum dots for the detection of a breast cancer biomarker. In this manuscript, we investigate the detection of the Bacillus anthracis protective antigen using antibodies conjugated with polymer-coated quantum dots. Kinetics of binding on the waveguide-based biosensor is reported. We compare the sensitivity of quantum dot labeled antibodies to those labeled with AlexaFluor and demonstrate the photostability of the former in our assay platform. In addition, we compare sulfydryl labeling of the antibody in the hinge region to that of nonspecific amine labeling. This is but the first step in developing a multiplex assay for such biomarkers on our waveguide platform.

  15. Low-NA single-mode LMA photonic crystal fiber amplifier

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Laurila, Marko; Scolari, Lara

    2011-01-01

    a spatially Distributed Mode Filter (DMF). This approach achieves SM performance in a short and straight rod fiber and allows preform tolerances to be compensated during draw. A low-NA SM rod fiber amplifier having a mode field diameter of ~60μm at 1064nm and a pump absorption of 27dB/m at 976nm...

  16. High core count single-mode multicore fiber for dense space division multiplexing

    DEFF Research Database (Denmark)

    Aikawa, K.; Sasaki, Y.; Amma, Y.

    2016-01-01

    Multicore fibers and few-mode fibers have the potential to realize dense-space-division multiplexing systems. Several dense-space-division multiplexing system transmission experiments over multicore fibers and few-mode fibers have been demonstrated so far. Multicore fibers, including recent resul...

  17. Measurement of peripheral electron temperature by electron cyclotron emission during the H-mode transition in JFT-2M tokamak

    International Nuclear Information System (INIS)

    Hoshino, Katsumichi; Yamamoto, Takumi; Kawashima, Hisato

    1987-01-01

    Time evolution and profile of peripheral electron temperature during the H-mode like transition in a tokamak plasma is measured using the second and third harmonic of electron cyclotron emission (ECE). The so called ''H-mode'' state which has good particle/energy confinement is characterized by sudden decrease in the spectral line intensity of deuterium molecule. Such a sudden decrease in the line intensity of D α with good energy confinement is found not only in divertor discharges, but also in limiter dischargs in JFT-2M tokamak. It is found by the measurement of ECE that the peripheral electron temperature suddenly increases in both of such phases. The relation between H-transition and the peripheral electron temperature or its profile is investigated. (author)

  18. Single-Photon Emission Computerized Tomography (SPECT in Neuropsychiatry: A Review

    Directory of Open Access Journals (Sweden)

    B. K. Puri

    1992-01-01

    Full Text Available Cranial single-photon emission computerized tomography (SPECT or SPET can now give regional cerebral blood flow images with a resolution approaching that of positron emission tomography (PET. In this paper, the use of high resolution SPECT neuroimaging in neuropsychiatric disorders, including Alzheimer's disease, multi-infarct dementia, Pick's disease, progressive supranuclear palsy, Korsakoff's psychosis, Creutzfeld-Jakob disease, Parkinson's disease, Huntington's disease, schizophrenia, mood disorders, obsessive–compulsive disorder, HIV infection and AIDS is reviewed. Finally, further potential research and clinical uses, based on ligand studies, are outlined.

  19. Hybrid Single Photon Emission Computed Tomography/Computed Tomography Sulphur Colloid Scintigraphy in Focal Nodular Hyperplasia

    International Nuclear Information System (INIS)

    Bhoil, Amit; Gayana, Shankramurthy; Sood, Ashwani; Bhattacharya, Anish; Mittal, Bhagwant Rai

    2013-01-01

    It is important to differentiate focal nodular hyperplasia (FNH), a benign condition of liver most commonly affecting women, from other neoplasm such as hepatic adenoma and metastasis. The functional reticuloendothelial features of FNH can be demonstrated by scintigraphy. We present a case of breast cancer in whom fluorodeoxyglucose positron emission tomography/computerized tomography (CT) showed a homogenous hyperdense lesion in liver, which on Tc99m sulfur colloid single-photon emission computed tomography/CT was found to have increased focal tracer uptake suggestive of FNH

  20. Characterization of continuous and pulsed emission modes of a hybrid micro focus x-ray source for medical imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Ghani, Muhammad U.; Wong, Molly D.; Ren, Liqiang; Wu, Di; Zheng, Bin [Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019 (United States); Rong, John X. [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030 (United States); Wu, Xizeng [Department of Radiology, University of Alabama at Birmingham, Birmingham, AL 35249 (United States); Liu, Hong, E-mail: liu@ou.edu [Center for Biomedical Engineering and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019 (United States)

    2017-05-01

    The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16 µm to 50 µm as the source output power changes from 10 to 39 W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (µA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22 µm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50 µm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications. - Highlights: • A micro focus x-ray source that operates in both continuous and pulse emission modes was quantitatively characterized. • The source output, beam quality, focal spot measurements, kV accuracy, spectra analyses and spatial resolution were measured. • Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam

  1. Characterization of continuous and pulsed emission modes of a hybrid micro focus x-ray source for medical imaging applications

    International Nuclear Information System (INIS)

    Ghani, Muhammad U.; Wong, Molly D.; Ren, Liqiang; Wu, Di; Zheng, Bin; Rong, John X.; Wu, Xizeng; Liu, Hong

    2017-01-01

    The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16 µm to 50 µm as the source output power changes from 10 to 39 W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (µA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22 µm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50 µm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications. - Highlights: • A micro focus x-ray source that operates in both continuous and pulse emission modes was quantitatively characterized. • The source output, beam quality, focal spot measurements, kV accuracy, spectra analyses and spatial resolution were measured. • Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam

  2. Near-roadway monitoring of vehicle emissions as a function of mode of operation for light-duty vehicles.

    Science.gov (United States)

    Wen, Dongqi; Zhai, Wenjuan; Xiang, Sheng; Hu, Zhice; Wei, Tongchuan; Noll, Kenneth E

    2017-11-01

    Determination of the effect of vehicle emissions on air quality near roadways is important because vehicles are a major source of air pollution. A near-roadway monitoring program was undertaken in Chicago between August 4 and October 30, 2014, to measure ultrafine particles, carbon dioxide, carbon monoxide, traffic volume and speed, and wind direction and speed. The objective of this study was to develop a method to relate short-term changes in traffic mode of operation to air quality near roadways using data averaged over 5-min intervals to provide a better understanding of the processes controlling air pollution concentrations near roadways. Three different types of data analysis are provided to demonstrate the type of results that can be obtained from a near-roadway sampling program based on 5-min measurements: (1) development of vehicle emission factors (EFs) for ultrafine particles as a function of vehicle mode of operation, (2) comparison of measured and modeled CO 2 concentrations, and (3) application of dispersion models to determine concentrations near roadways. EFs for ultrafine particles are developed that are a function of traffic volume and mode of operation (free flow and congestion) for light-duty vehicles (LDVs) under real-world conditions. Two air quality models-CALINE4 (California Line Source Dispersion Model, version 4) and AERMOD (American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model)-are used to predict the ultrafine particulate concentrations near roadways for comparison with measured concentrations. When using CALINE4 to predict air quality levels in the mixing cell, changes in surface roughness and stability class have no effect on the predicted concentrations. However, when using AERMOD to predict air quality in the mixing cell, changes in surface roughness have a significant impact on the predicted concentrations. The paper provides emission factors (EFs) that are a function of traffic volume and mode of

  3. Aphasia following left thalamic hemorrhage. A study by Western Aphasia Battery and single photon emission CT

    Energy Technology Data Exchange (ETDEWEB)

    Makishita, Hideo; Miyasaka, Motomaro; Tanizaki, Yoshio; Yanagisawa, Nobuo; Sugishita, Morihiro

    1984-07-01

    A report is given of 7 patients with left thalamic hemorrhage in the chronic stage (from 1.5 months to 4.5 months) in which language disorders were examined by Western Aphasia Battery (WAB) and cerebral blood flow was measured by single photon emission CT. Examination of language by WAB revealed 4 aphasics out of 7 cases, and 3 patients had no language deficit. The patient with Wernicke's aphasia showed low density area only in the left posterior thalamus in X-ray CT, and revealed severe low blood flow area extending to left temporal lobe in emission CT. In the case with transcortical sensory aphasia, although X-ray CT showed no obvious low density area, emission CT revealed moderate low flow area in the left temporooccipital region and low blood flow at the left thalamus. In one of the two patients classified as anomic aphasia, emission CT showed slight low flow area at the temporo-occipital region similar to the case with transcortical sensory aphasia. In another case with anomic aphasia there was a wide low density area all over the left thalamus and midline shift to the right in X-ray CT, and emission CT showed severe low blood flow in the same region spreading widely toward the cerebral surface. In all of the 3 patients without aphasia, emission CT showed low flow region restricted to the left thalamus.

  4. Nanometer-scale discernment of field emission from tungsten surface with single carbon monoxide molecule

    Science.gov (United States)

    Matsunaga, Soichiro; Suwa, Yuji; Katagiri, Souichi

    2017-12-01

    Unusual quantized beam fluctuations were found in the emission current from a cold-field emitter (CFE) operating in an extremely high vacuum of 10-10 Pa. To clarify the microscopic mechanism behind these fluctuations, we developed a new calculation method to evaluate the field emission from a heterogeneous surface under a strong electric field of 4 × 109 V/m by using the local potential distribution obtained by a first-principles calculation, instead of by using the work function. As a result of the first-principles calculations of a single molecule adsorbed on a tungsten surface, we found that dissociative adsorption of a carbon monoxide (CO) molecule enhances the emission current by changing the potential barrier in the area surrounding the C and O adatoms when these two atoms are placed at their most stable positions. It is also found that the migration of the O atom from the most stable position reduces the emission current. These types of enhancement and reduction of the emission current quantitatively explain the observed quantized fluctuations of the CFE emission current.

  5. Investigation of pyroelectric electron emission from monodomain lithium niobate single crystals

    International Nuclear Information System (INIS)

    Bourim, El Mostafa; Moon, Chang-Wook; Lee, Seung-Woon; Kyeong Yoo, In

    2006-01-01

    The behaviors of thermally stimulated electron emission from pyroelectric monodomain lithium niobate single crystal (LiNbO 3 ) were investigated by utilizing a Si p-n junction photodiode as electron detector and a receptive electron beam resist (E-beam resist) as electron collector. In high vacuum (10 -6 Torr), the pyroelectric electron emission (PEE) was found to depend on the exposed emitting polar crystal surface (+Z face or -Z face) and was significantly influenced by the emitter-electron receiver gap distances. Thus, the PEE from +Z face was detected during heating and was activated, in small gaps ( 2 mm) the emission was simply mastered by field emission effect. Whereas, The PEE from -Z face was detected during cooling and was solely due to the field ionization effect. Therewith, for small gaps ( 2 mm) PEE was governed by field ionization generating a soft and continuous plasma ambient atmosphere. Significant decrease of electron emission current was observed from +Z face after successive thermal cycles. A fast and fully emission recovery was established after a brief exposure of crystal to a poor air vacuum of 10 -1 Torr

  6. Low temperature synthesis and field emission characteristics of single to few layered graphene grown using PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avshish; Khan, Sunny; Zulfequar, M.; Harsh; Husain, Mushahid, E-mail: mush_reslab@rediffmail.com

    2017-04-30

    Highlights: • Graphene was synthesized by PECVD system at a low temperature of 600 °C. • From different characterization techniques, the presence of single and few layered graphene was confirmed. • X-ray diffraction pattern of the graphene showed single crystalline nature of the film. • The as-grown graphene films were observed extremely good field emitters with long term emission current stability. - Abstract: In this work, high-quality graphene has successfully been synthesized on copper (Cu) coated Silicon (Si) substrate at very large-area by plasma enhanced chemical vapor deposition system. This method is low cost and highly effective for synthesizing graphene relatively at low temperature of 600 °C. Electron microscopy images have shown that surface morphology of the grown samples is quite uniform consisting of single layered graphene (SLG) to few layered graphene (FLG). Raman spectra reveal that graphene has been grown with high-quality having negligible defects and the observation of G and G' peaks is also an indicative of stokes phonon energy shift caused due to laser excitation. Scanning probe microscopy image also depicts the synthesis of single to few layered graphene. The field emission characteristics of as-grown graphene samples were studied in a planar diode configuration at room temperature. The graphene samples were observed to be a good field emitter having low turn-on field, higher field amplification factor and long term emission current stability.

  7. A Comparison between Boundary and Continuous Conduction Modes in Single Phase PFC Using 600V Range Devices

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2015-01-01

    This paper presents an analysis and comparison of boundary conduction mode (BCM) and continuous conduction mode (CCM) in single phase power factor correction (PFC) applications. The comparison is based on double pulse tester (DPT) characterization results of state-of-the-art superjunction devices...... in the 600V range. The measured switching energy is used to evaluate the devices performance in a conventional PFC. This data is used together with a mathematical model for prediction of the conducted electromagnetic interference (EMI). This allows comparing the different devices in BCM and CCM operation...

  8. Strong coupling between a single nitrogen-vacancy spin and the rotational mode of diamonds levitating in an ion trap

    Science.gov (United States)

    Delord, T.; Nicolas, L.; Chassagneux, Y.; Hétet, G.

    2017-12-01

    A scheme for strong coupling between a single atomic spin and the rotational mode of levitating nanoparticles is proposed. The idea is based on spin readout of nitrogen-vacancy centers embedded in aspherical nanodiamonds levitating in an ion trap. We show that the asymmetry of the diamond induces a rotational confinement in the ion trap. Using a weak homogeneous magnetic field and a strong microwave driving we then demonstrate that the spin of the nitrogen-vacancy center can be strongly coupled to the rotational mode of the diamond.

  9. Towards a single European electricity market. A structured approach to regulatory mode decision-making

    International Nuclear Information System (INIS)

    De Jong, H.M.

    2009-01-01

    This study focuses on the processes through which the rules and regulations that govern European electricity markets - and inherently, their integration process - are established. So far, European policy makers have largely followed a 'trial-and-error' approach to finding an appropriate regulatory mode (process) for dealing effectively with market integration issues. This unstructured approach to regulatory mode selection leads to several problems: - Today's trial-and-error strategy of shifting from one regulatory mode to another is time-consuming. - In the regulatory mode selection process, certain key principles of good governance are insufficiently considered. - European regulatory processes are experienced as vague, intransparent, and illegitimate by 'outside' stakeholders. This study develops a 'structured approach to regulatory mode decision-making' (STARMODE) based on the theory of decision modelling in policy management and a case study exploring three key market integration issues in the field of electricity markets: interconnector investment, congestion management and market transparency. The main objective is to present a systematic and comprehensive framework for analysing and improving regulatory mode decision-making in the context of the European Union, focusing on electricity market integration. The STARMODE approach is generally applicable to (and relevant for) European market integration issues in industries characterized by a natural monopoly and/or an essential service. The approach may also contribute to national regulatory mode decision-making and multi-state decision-making in other continents.

  10. Baseline performance and emissions data for a single-cylinder, direct-injected diesel engine

    Science.gov (United States)

    Dezelick, R. A.; Mcfadden, J. J.; Ream, L. W.; Barrows, R. F.

    1983-01-01

    Comprehensive fuel consumption, mean effective cylinder pressure, and emission test results for a supercharged, single-cylinder, direct-injected, four-stroke-cycle, diesel test engine are documented. Inlet air-to-exhaust pressure ratios were varied from 1.25 to 3.35 in order to establish the potential effects of turbocharging techniques on engine performance. Inlet air temperatures and pressures were adjusted from 34 to 107 C and from 193 to 414 kPa to determine the effects on engine performance and emissions. Engine output ranged from 300 to 2100 kPa (brake mean effective pressure) in the speed range of 1000 to 3000 rpm. Gaseous and particulate emission rates were measured. Real-time values of engine friction and pumping loop losses were measured independently and compared with motored engine values.

  11. Simulation Study of Single Photon Emission Computed Tomography for Industrial Applications

    International Nuclear Information System (INIS)

    Roy, Tushar; Sarkar, P. S.; Sinha, Amar

    2008-01-01

    SPECT (Single Photon Emission Computed Tomography) provides for an invaluable non-invasive technique for the characterization and activity distribution of the gamma-emitting source. For many applications of radioisotopes for medical and industrial application, not only the positional information of the distribution of radioisotopes is needed but also its strength. The well-established X-ray radiography or transmission tomography techniques do not yield sufficient quantitative information about these objects. Emission tomography is one of the important methods for such characterization. Application of parallel beam, fan beam and 3D cone beam emission tomography methods have been discussed in this paper. Simulation studies to test these algorithms have been carried out to validate the technique.

  12. The contribution of single photon emission computed tomography in the clinical assessment of Alzheimer type dementia

    International Nuclear Information System (INIS)

    Boudousq, V.; Collombier, L.; Kotzki, P.O.

    1999-01-01

    Interest of brain single-photon emission computed tomography to support clinical diagnosis of Alzheimer-type dementia is now established. Numerous studies have reported a decreased perfusion in the association cortex of the parietal lobe and the posterior temporal regions. In patients with mild cognitive complaints, the presence of focal hypoperfusion may increase substantially the probability of the disease. In addition, emission tomography emerges as a helpful tool in situation in which there is diagnostic doubt. In this case, the presence of temporo-parietal perfusion deficit associated with hippocampal atrophy on MRI or X-ray computed tomography contributes to diagnostic accuracy. However, some studies suggest that emission tomography may be useful for preclinical prediction of Alzheimer's disease and to predict cognitive decline. (author)

  13. Thermal field emission observation of single-crystal LaB6

    International Nuclear Information System (INIS)

    Nagata, H.; Harada, K.; Shimizu, R.

    1990-01-01

    TFE (thermal field emission) properties of LaB 6 left-angle 100 right-angle and left-angle 310 right-angle single crystals were investigated by emission pattern observation. It was found that field evaporation with the tip temperature held at ∼1500 degree C is very useful to get a clean pattern of fourfold symmetry. Each of four bright spots in the clean pattern was presumed to correspond to left-angle 310 right-angle emission. It is proposed, as the most appropriate operating condition, to use the left-angle 310 right-angle LaB 6 tip at a temperature ∼1000 degree C in vacuum of 10 -9 Torr region, promising a new TF emitter of high brightness and stability for practical use

  14. Experience with Aerosol Generation During Rotary Mode Core Sampling in the Hanford Single Shell Waste Tanks

    International Nuclear Information System (INIS)

    SCHOFIELD, J.S.

    1999-01-01

    This document provides data on aerosol concentrations in tank head spaces, total mass of aerosols in the tank head space and mass of aerosols sent to the exhauster during Rotary Mode Core Sampling from November 1994 through April 1999

  15. Design and prototyping of self-centering optical single-mode fiber alignment structures

    International Nuclear Information System (INIS)

    Ebraert, Evert; Gao, Fei; Thienpont, Hugo; Van Erps, Jürgen; Beri, Stefano; Watté, Jan

    2016-01-01

    The European Commission’s goal of providing each European household with at least a 30 Mb s −1 Internet connection by 2020 would be facilitated by a widespread deployment of fibre-to-the-home, which would in turn be sped up by the development of connector essential components, such as high-precision alignment features. Currently, the performance of state-of-the-art physical contact optical fiber connectors is limited by the tolerance on the cladding of standard telecom-grade single-mode fiber (SMF), which is typically smaller than  ±1 μ m. We propose to overcome this limit by developing micro-spring-based self-centering alignment structures (SCAS) for SMF-connectors. We design these alignment structures with robustness and low-cost replication in mind, allowing for large-scale deployment. Both theoretical and finite element analysis (FEA) models are used to determine the optimal dimensions of the beams of which the micro-springs of the SCAS are comprised. Two topologies of the SCAS, consisting of three and four micro-springs respectively, are investigated for two materials: polysulfone (PSU) and polyetherimide (PEI). These materials hold great potential for high-performance fiber connectors while being compatible with low-cost production and with the harsh environmental operation conditions of those connectors. The theory and FEA agree well (<3% difference) for a simple micro-spring. When including a pedestal on the micro-spring (to bring it further away from the fiber) and for shorter spring lengths the agreement worsens. This is due to spring compression effects not being taken into account in our theoretical model. Prototypes are successfully fabricated using deep proton writing and subsequently characterized. The controlled insertion of an SMF in the SCAS is investigated and we determine that a force of 0.11 N is required. The fiber insertion also causes an out-of-plane deformation of the micro-springs in the SCAS of about 7 μ m, which is no

  16. The entanglement of two moving atoms interacting with a single-mode field via a three-photon process

    International Nuclear Information System (INIS)

    Chao, Wu; Mao-Fa, Fang

    2010-01-01

    In this paper, the entanglement of two moving atoms induced by a single-mode field via a three-photon process is investigated. It is shown that the entanglement is dependent on the category of the field, the average photon number N, the number p of half-wave lengths of the field mode and the atomic initial state. Also, the sudden death and the sudden birth of the entanglement are detected in this model and the results show that the existence of the sudden death and the sudden birth depends on the parameter and the category of the mode field. In addition, the three-photon process is a higher order nonlinear process. (general)

  17. PET and Single-Photon Emission Computed Tomography in Brain Concussion.

    Science.gov (United States)

    Raji, Cyrus A; Henderson, Theodore A

    2018-02-01

    This article offers an overview of the application of PET and single photon emission computed tomography brain imaging to concussion, a type of mild traumatic brain injury and traumatic brain injury, in general. The article reviews the application of these neuronuclear imaging modalities in cross-sectional and longitudinal studies. Additionally, this article frames the current literature with an overview of the basic physics and radiation exposure risks of each modality. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Degenerative dementia: nosological aspects and results of single photon emission computed tomography

    International Nuclear Information System (INIS)

    Dubois, B.; Habert, M.O.

    1999-01-01

    Ten years ago, the diagnosis discussion of a dementia case for the old patient was limited to two pathologies: the Alzheimer illness and the Pick illness. During these last years, the frame of these primary degenerative dementia has fallen into pieces. The different diseases and the results got with single photon emission computed tomography are discussed. for example: fronto-temporal dementia, primary progressive aphasia, progressive apraxia, visio-spatial dysfunction, dementia at Lewy's bodies, or cortico-basal degeneration. (N.C.)

  19. Imaging by single photon emission computed tomography: interest in the pre surgical check up of epilepsy

    International Nuclear Information System (INIS)

    Biraben, A.; Bernard, A.M.

    1999-01-01

    With the single photon emission computed tomography, it is a more reliable technique that is at someone's disposal, especially to limit spatially the evolution of epilepsy crisis before any surgery act. The determination of the precise area is necessary to make sure that the crisis come really from this area and the determination of the functionality of this area is checked to be sure that the ablation of the zone will not lead to an unacceptable functional deficit. (N.C.)

  20. Single Mode Theory for Impedance Eduction in Large-Scale Ducts with Grazing Flow

    Science.gov (United States)

    Watson, Willie R.; Gerhold, Carl H.; Jones, Michael G.; June, Jason C.

    2014-01-01

    An impedance eduction theory for a rigid wall duct containing an acoustic liner with an unknown impedance and uniform grazing flow is presented. The unique features of the theory are: 1) non-planar waves propagate in the hard wall sections of the duct, 2) input data consist solely of complex acoustic pressures acquired on a wall adjacent to the liner, and 3) multiple higher-order modes may exist in the direction perpendicular to the liner and the opposite rigid wall. The approach is to first measure the axial propagation constant of a dominant higher-order mode in the liner sample section. This axial propagation constant is then used in conjunction with a closed-form solution to a reduced form of the convected Helmholtz equation and the wall impedance boundary condition to educe the liner impedance. The theory is validated on a conventional liner whose impedance spectrum is educed in two flow ducts with different cross sections. For the frequencies and Mach numbers of interest, no higher-order modes propagate in the hard wall sections of the smaller duct. A benchmark method is used to educe the impedance spectrum in this duct. A dominant higher-order vertical mode propagates in the larger duct for similar test conditions, and the current theory is applied to educe the impedance spectrum. Results show that when the theory is applied to data acquired in the larger duct with a dominant higher-order vertical mode, the same impedance spectra is educed as that obtained in the small duct where only the plane wave mode is present and the benchmark method is used. This result holds for each higher-order vertical mode that is considered.

  1. Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio

    2016-01-01

    We have fabricated the first single-mode step-index and humidity insensitive polymer optical fiber operating in the 850 nm wavelength ranges. The step-index preform is fabricated using injection molding, which is an efficient method for cost effective, flexible and fast preparation of the fiber...... preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed...... SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured...

  2. Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres

    Science.gov (United States)

    Gissibl, Timo; Thiele, Simon; Herkommer, Alois; Giessen, Harald

    2016-01-01

    Micro-optics are widely used in numerous applications, such as beam shaping, collimation, focusing and imaging. We use femtosecond 3D printing to manufacture free-form micro-optical elements. Our method gives sub-micrometre accuracy so that direct manufacturing even on single-mode fibres is possible. We demonstrate the potential of our method by writing different collimation optics, toric lenses, free-form surfaces with polynomials of up to 10th order for intensity beam shaping, as well as chiral photonic crystals for circular polarization filtering, all aligned onto the core of the single-mode fibres. We determine the accuracy of our optics by analysing the output patterns as well as interferometrically characterizing the surfaces. We find excellent agreement with numerical calculations. 3D printing of microoptics can achieve sufficient performance that will allow for rapid prototyping and production of beam-shaping and imaging devices. PMID:27339700

  3. The use of Lorentz group formalism in solving polarization effects of a birefringent single mode optical fiber

    International Nuclear Information System (INIS)

    Ishiekwene, G.C.; Brown, C.S.; Mensah, S.Y.; Bak, A.E.

    2000-07-01

    A theoretical analysis on the polarization effects of a light beam propagating in a birefringent single-mode fiber is presented. We derive a system of differential equations representing the evolution of Stokes parameters and illustrate their application to polarization effects in a straight birefringent single mode optical fiber. The solutions to the set of equations are obtained using specifically the methods of the unified formalism for polarization optics which adopt the use of the Stokes-Mueller equation and the Lorentz group to model polarization phenomena in media such as optical fibers. The analytical results presented using this approach are identical to results obtained from other conventional methods. We observe the characteristic exponential decrease in the total intensity of the input light due to attenuation by the fiber. (author)

  4. A tunable and switchable single-longitudinal-mode dual-wavelength fiber laser with a simple linear cavity.

    Science.gov (United States)

    He, Xiaoying; Fang, Xia; Liao, Changrui; Wang, D N; Sun, Junqiang

    2009-11-23

    A simple linear cavity erbium-doped fiber laser based on a Fabry-Perot filter which consists of a pair of fiber Bragg gratings is proposed for tunable and switchable single-longitudinal-mode dual-wavelength operation. The single-longitudinal-mode is obtained by the saturable absorption of an unpumed erbium-doped fiber together with a narrow-band fiber Bragg grating. Under the high pump power (>166 mW) condition, the stable dual-wavelength oscillation with uniform amplitude can be realized by carefully adjusting the polarization controller in the cavity. Wavelength selection and switching are achieved by tuning the narrow-band fiber Bragg grating in the system. The spacing of the dual-wavelength can be selected at 0.20 nm (approximately 25.62 GHz), 0.22 nm (approximately 28.19 GHz) and 0.54 nm (approximately 69.19 GHz).

  5. Quantum properties of a superposition of squeezed displaced two-mode vacuum and single-photon states

    International Nuclear Information System (INIS)

    El-Orany, Faisal A A; Obada, A-S F; M Asker, Zafer; Perina, J

    2009-01-01

    In this paper, we study some quantum properties of a superposition of displaced squeezed two-mode vacuum and single-photon states, such as the second-order correlation function, the Cauchy-Schwarz inequality, quadrature squeezing, quasiprobability distribution functions and purity. These type of states include two mechanisms, namely interference in phase space and entanglement. We show that these states can exhibit sub-Poissonian statistics, squeezing and deviate from the classical Cauchy-Schwarz inequality. Moreover, the amount of entanglement in the system can be increased by increasing the squeezing mechanism. In the framework of the quasiprobability distribution functions, we show that the single-mode state can tend to the thermal state based on the correlation mechanism. A generation scheme for such states is given.

  6. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    International Nuclear Information System (INIS)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-01-01

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed

  7. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Hiroaki; Sul, Soohwan [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States); Ge, Nien-Hui, E-mail: nhge@uci.edu [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States)

    2013-08-30

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  8. Single and two-mode mechanical squeezing of an optically levitated nanodiamond via dressed-state coherence

    International Nuclear Information System (INIS)

    Ge, Wenchao; Bhattacharya, M

    2016-01-01

    Nonclassical states of macroscopic objects are promising for ultrasensitive metrology as well as testing quantum mechanics. In this work, we investigate dissipative mechanical quantum state engineering in an optically levitated nanodiamond. First, we study single-mode mechanical squeezed states by magnetically coupling the mechanical motion to a dressed three-level system provided by a nitrogen-vacancy center in the nanoparticle. Quantum coherence between the dressed levels is created via microwave fields to induce a two-phonon transition, which results in mechanical squeezing. Remarkably, we find that in ultrahigh vacuum quantum squeezing is achievable at room temperature with feedback cooling. For moderate vacuum, quantum squeezing is possible with cryogenic temperature. Second, we present a setup for two mechanical modes coupled to the dressed three levels, which results in two-mode squeezing analogous to the mechanism of the single-mode case. In contrast to previous works, our study provides a deterministic method for engineering macroscopic squeezed states without the requirement for a cavity. (paper)

  9. Single and two-mode mechanical squeezing of an optically levitated nanodiamond via dressed-state coherence

    Science.gov (United States)

    Ge, Wenchao; Bhattacharya, M.

    2016-10-01

    Nonclassical states of macroscopic objects are promising for ultrasensitive metrology as well as testing quantum mechanics. In this work, we investigate dissipative mechanical quantum state engineering in an optically levitated nanodiamond. First, we study single-mode mechanical squeezed states by magnetically coupling the mechanical motion to a dressed three-level system provided by a nitrogen-vacancy center in the nanoparticle. Quantum coherence between the dressed levels is created via microwave fields to induce a two-phonon transition, which results in mechanical squeezing. Remarkably, we find that in ultrahigh vacuum quantum squeezing is achievable at room temperature with feedback cooling. For moderate vacuum, quantum squeezing is possible with cryogenic temperature. Second, we present a setup for two mechanical modes coupled to the dressed three levels, which results in two-mode squeezing analogous to the mechanism of the single-mode case. In contrast to previous works, our study provides a deterministic method for engineering macroscopic squeezed states without the requirement for a cavity.

  10. Phonon Self-Energy Corrections to Nonzero Wave-Vector Phonon Modes in Single-Layer Graphene

    Science.gov (United States)

    Araujo, P. T.; Mafra, D. L.; Sato, K.; Saito, R.; Kong, J.; Dresselhaus, M. S.

    2012-07-01

    Phonon self-energy corrections have mostly been studied theoretically and experimentally for phonon modes with zone-center (q=0) wave vectors. Here, gate-modulated Raman scattering is used to study phonons of a single layer of graphene originating from a double-resonant Raman process with q≠0. The observed phonon renormalization effects are different from what is observed for the zone-center q=0 case. To explain our experimental findings, we explored the phonon self-energy for the phonons with nonzero wave vectors (q≠0) in single-layer graphene in which the frequencies and decay widths are expected to behave oppositely to the behavior observed in the corresponding zone-center q=0 processes. Within this framework, we resolve the identification of the phonon modes contributing to the G⋆ Raman feature at 2450cm-1 to include the iTO+LA combination modes with q≠0 and also the 2iTO overtone modes with q=0, showing both to be associated with wave vectors near the high symmetry point K in the Brillouin zone.

  11. A sensitivity-enhanced refractive index sensor using a single-mode thin-core fiber incorporating an abrupt taper.

    Science.gov (United States)

    Shi, Jie; Xiao, Shilin; Yi, Lilin; Bi, Meihua

    2012-01-01

    A sensitivity-enhanced fiber-optic refractive index (RI) sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF) between two sections of single-mode fibers (SMFs). The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI). An abrupt taper (tens of micrometers long) made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity.

  12. A Sensitivity-Enhanced Refractive Index Sensor Using a Single-Mode Thin-Core Fiber Incorporating an Abrupt Taper

    Directory of Open Access Journals (Sweden)

    Jie Shi

    2012-04-01

    Full Text Available A sensitivity-enhanced fiber-optic refractive index (RI sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF between two sections of single-mode fibers (SMFs. The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI. An abrupt taper (tens of micrometers long made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity.

  13. Single-mode optical fiber design with wide-band ultra low bending-loss for FTTH application.

    Science.gov (United States)

    Watekar, Pramod R; Ju, Seongmin; Han, Won-Taek

    2008-01-21

    We propose a new design of a single-mode optical fiber (SMF) which exhibits ultra low bend sensitivity over a wide communication band (1.3 microm to 1.65 microm). A five-cladding fiber structure has been proposed to minimize the bending loss, estimated to be as low as 4.4x10(-10) dB/turn for the bend radius of 10 mm.

  14. Toward single-mode UV to near-IR guidance using hollow-core anti-resonant silica fiber

    DEFF Research Database (Denmark)

    Habib, Md Selim; Antonio-Lopez, Jose Enrique; Van Newkirk, Amy

    2017-01-01

    Hollow-core anti-resonant (HC-AR) fibers with a “negative-curvature” of the core-cladding boundary have been extensively studied over the past few years owing to their low loss and wide transmission bandwidths. The key unique feature of the HC-AR fiber is that the coupling between the core and cl...... a silica HC-AR fiber having a single ring of 7 non-touching capillaries, designed to have effectively single-mode operation and low loss from UV to near-IR....

  15. “MODAL NOISE” IN SINGLE-MODE FIBERS: A CAUTIONARY NOTE FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Schwab, Christian, E-mail: shalverson@psu.edu [Macquarie University, Sydney, NSW 2109 (Australia)

    2015-12-01

    Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical “seeing-limited” instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as “modal noise,” are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.

  16. Effects of ethanol on combustion and emissions of a gasoline engine operating with different combustion modes

    OpenAIRE

    Ojapah, MM; Zhao, H; Zhang, Y

    2016-01-01

    The introduction of fuel economy and CO2 emission legislations for passenger cars in many countries and regions has spurred the research and development of more efficient gasoline engines. The pumping loss at part-load operations is a major factor for the higher fuel consumption of spark ignition (SI) gasoline engines than the diesel engines. Various approaches have been identified to reduce the pumping loss at part-load operations, leading to improved fuel economy, including Early Intake Val...

  17. Explanation of the quantum phenomenon of off-resonant cavity-mode emission

    Science.gov (United States)

    Echeverri-Arteaga, Santiago; Vinck-Posada, Herbert; Gómez, Edgar A.

    2018-04-01

    We theoretically investigate the unexpected occurrence of an extra emission peak that has been experimentally observed in off-resonant studies of cavity QED systems. Our results within the Markovian master equation approach successfully explain why the central peak arises, and how it reveals that the system is suffering a dynamical phase transition induced by the phonon-mediated coupling. Our findings are in qualitative agreement with previous reported experimental results, and the fundamental physics behind this quantum phenomenon is understood.

  18. Source region and growth analysis of narrowband Z-mode emission

    Czech Academy of Sciences Publication Activity Database

    Menietti, J. D.; Yoon, P. H.; Píša, David; Ye, S.; Y.; Santolík, Ondřej; Arridge, C. S.; Gurnett, D. A.; Coates, A. J.

    2016-01-01

    Roč. 121, č. 12 (2016), s. 11929-11942 ISSN 2169-9380 Grant - others:AV ČR(CZ) AP1401 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:68378289 Keywords : auroral radio emissions * magnetic-field * plasma * magnetosphere * radiation * acceleration * pectrometer * electrons * density Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.733, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/2016JA022913/abstract

  19. Fully quantum-mechanical dynamic analysis of single-photon transport in a single-mode waveguide coupled to a traveling-wave resonator

    International Nuclear Information System (INIS)

    Hach, Edwin E. III; Elshaari, Ali W.; Preble, Stefan F.

    2010-01-01

    We analyze the dynamics of single-photon transport in a single-mode waveguide coupled to a micro-optical resonator by using a fully quantum-mechanical model. We examine the propagation of a single-photon Gaussian packet through the system under various coupling conditions. We review the theory of single-photon transport phenomena as applied to the system and we develop a discussion on the numerical technique we used to solve for dynamical behavior of the quantized field. To demonstrate our method and to establish robust single-photon results, we study the process of adiabatically lowering or raising the energy of a single photon trapped in an optical resonator under active tuning of the resonator. We show that our fully quantum-mechanical approach reproduces the semiclassical result in the appropriate limit and that the adiabatic invariant has the same form in each case. Finally, we explore the trapping of a single photon in a system of dynamically tuned, coupled optical cavities.

  20. Theoretical and experimental study on active sound transmission control based on single structural mode actuation using point force actuators.

    Science.gov (United States)

    Sanada, Akira; Tanaka, Nobuo

    2012-08-01

    This study deals with the feedforward active control of sound transmission through a simply supported rectangular panel using vibration actuators. The control effect largely depends on the excitation method, including the number and locations of actuators. In order to obtain a large control effect at low frequencies over a wide frequency, an active transmission control method based on single structural mode actuation is proposed. Then, with the goal of examining the feasibility of the proposed method, the (1, 3) mode is selected as the target mode and a modal actuation method in combination with six point force actuators is considered. Assuming that a single input single output feedforward control is used, sound transmission in the case minimizing the transmitted sound power is calculated for some actuation methods. Simulation results showed that the (1, 3) modal actuation is globally effective at reducing the sound transmission by more than 10 dB in the low-frequency range for both normal and oblique incidences. Finally, experimental results also showed that a large reduction could be achieved in the low-frequency range, which proves the validity and feasibility of the proposed method.

  1. Enhancement of single mode operation in coaxial optical waveguide using DB boundary conditions

    Science.gov (United States)

    Lohia, Pooja; Prajapati, Y.; Saini, J. P.; Rai, B. S.

    2014-11-01

    In this study, a competent numerical strategy to compute the dispersion of optical waveguides is presented and propagation of electromagnetic waves in a coaxial optical waveguide with DB boundary conditions is instigated. For this intend, cylindrical coordinates are here being used to derive the DB boundary conditions and to obtain field components for the modes. The propagation constant for the waveguide to be studied is determined by solving the Bessel and the modified Bessel functions. The cutoff frequencies for various lower order modes have been calculated and their dispersion characteristics are plotted correspondingly. The behavior of the coaxial optical waveguide under DB boundary conditions is shown to be significantly different from that of coaxial optical waveguide and conventional optical waveguide under traditional or tangential boundary conditions. Finally, the effect of waveguide dimensions on the mode cutoff frequencies and fabrication issues are also addressed.

  2. SISGR: Room Temperature Single-Molecule Detection and Imaging by Stimulated Emission Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xiaoliang Sunney [Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry and Chemical Biology

    2017-03-13

    Single-molecule spectroscopy has made considerable impact on many disciplines including chemistry, physics, and biology. To date, most single-molecule spectroscopy work is accomplished by detecting fluorescence. On the other hand, many naturally occurring chromophores, such as retinal, hemoglobin and cytochromes, do not have detectable fluorescence. There is an emerging need for single-molecule spectroscopy techniques that do not require fluorescence. In the last proposal period, we have successfully demonstrated stimulated emission microscopy, single molecule absorption, and stimulated Raman microscopy based on a high-frequency modulation transfer technique. These first-of-a- kind new spectroscopy/microscopy methods tremendously improved our ability to observe molecules that fluorescence weakly, even to the limit of single molecule detection for absorption measurement. All of these methods employ two laser beams: one (pump beam) excites a single molecule to a real or virtual excited state, and the other (probe beam) monitors the absorption/emission property of the single. We extract the intensity change of the probe beam with high sensitivity by implementing a high-frequency phase-sensitive detection scheme, which offers orders of magnitude improvement in detection sensitivity over direct absorption/emission measurement. However, single molecule detection based on fluorescence or absorption is fundamentally limited due to their broad spectral response. It is important to explore other avenues in single molecule detection and imaging which provides higher molecular specificity for studying a wide variety of heterogeneous chemical and biological systems. This proposal aimed to achieve single-molecule detection sensitivity with near resonance stimulated Raman scattering (SRS) microscopy. SRS microscopy was developed in our lab as a powerful technique for imaging heterogeneous samples based on their intrinsic vibrational contrasts, which provides much higher molecular

  3. Single-temporal-mode photon generation beyond the low-power regime

    DEFF Research Database (Denmark)

    McKinstrie, C. J.; Christensen, Jesper Bjerge; Rottwitt, Karsten

    2017-01-01

    Nondegenerate four-wave mixing in a strongly-birefringent fiber generates signal and idler photons that are associated with only one pair of temporal modes, for a wide range of pump powers. Nonlinear phase modulation degrades the heralded-signal purity only slightly.......Nondegenerate four-wave mixing in a strongly-birefringent fiber generates signal and idler photons that are associated with only one pair of temporal modes, for a wide range of pump powers. Nonlinear phase modulation degrades the heralded-signal purity only slightly....

  4. Fracture mode during cyclic loading of implant-supported single-tooth restorations

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Kleven, Erik; Gotfredsen, Klaus

    2012-01-01

    restorations of zirconia abutment-retained crowns with zirconia copings veneered with glass-ceramics (n=8) and feldspathic ceramics (n=8). The control group was composed of 16 metal ceramic restorations of titanium abutment-retained crowns with gold alloy copings veneered with glass (n=8) and feldspathic...... ceramics (n=8). The palatal surfaces of the crowns were exposed to cyclic loading of 800 N with a frequency of 2 Hz, which continued to 4.2 million cycles or until fracture of the copings, abutments, or implants. The number of cycles and the fracture modes were recorded. The fracture modes were analyzed...

  5. On the effectiveness of single and multiple base station sleep modes in cellular networks

    OpenAIRE

    Marsan, Marco Ajmone; Chiaraviglio, Luca; Ciullo, Delia; Meo, Michela

    2013-01-01

    In this paper we study base station sleep modes that, by reducing power consumption in periods of low traffic, improve the energy efficiency of cellular access networks. We assume that when some base stations enter sleep mode, radio coverage and service provisioning are provided by the base stations that remain active, so as to guarantee that service is available over the whole area at all times. This may be an optimistic assumption in the case of the sparse base station layouts typical of ru...

  6. Brain receptor single-photon emission computer tomography with 123I Datscan in Parkinson's disease

    International Nuclear Information System (INIS)

    Minchev, D.; Peshev, N.; Kostadinova, I.; Grigorova, O.; Trindev, P.; Shotekov, P.

    2005-01-01

    Clinical aspects of Parkinson's disease are not enough for the early diagnosis of the disease. Positron emission tomography and the receptor single - photon emission tomography can be used for imaging functional integrity of nigrostriatal dopaminergic structures. 24 patient (17 men and 7 women) were investigated. 20 of them are with Parkinson's disease and 4 are with essential tremor. The radiopharmaceutical - 123I-Datscan (ioflupane, bind with 123I) represent a cocaine analogue with selective affinity to dopamine transporters, located in the dopaminergic nigrostriatal terminals in the striatum. Single - photon emission computer tomography was performed with SPECT gamma camera (ADAC, SH Epic detector). The scintigraphic study was made 3 to 6 hours after intravenous injection of the radiopharmaceutical - 123I- Datscan in dose 185 MBq. 120 frames are registered with duration of each one 22 seconds and gamma camera rotation 360. After generation of transversal slices we generated two composites pictures. The first composite picture image the striatum, the second - the occipital region. Two ratios were calculated representing the uptake of the radiopharmaceutical in the left and right striatum. Qualitative and quantitative criteria were elaborated for evaluating the scintigraphic patterns. Decreased, nonhomogeneous and asymmetric uptake of the radiopharmaceutical coupled with low quantitative parameters in range from 1.44 to 2.87 represents the characteristic scintigraphic pattern for Parkinson's disease with clear clinical picture. Homogenous with high intensity and symmetric uptake of the radiopharmaceutical in the striatum coupled with his clear frontier and with quantitative parameters up to 4.40 represent the scintigraphic pattern in two patients with essential tremor. Receptor single - photon emission computer tomography with 123I - Datscan represents an accurate nuclear-medicine method for precise diagnosis of Parkinson's disease and for its differentiation from

  7. A single source microwave photonic filter using a novel single-mode fiber to multimode fiber coupling technique.

    Science.gov (United States)

    Chang, John; Fok, Mable P; Meister, James; Prucnal, Paul R

    2013-03-11

    In this paper we present a fully tunable and reconfigurable single-laser multi-tap microwave photonic FIR filter that utilizes a special SM-to-MM combiner to sum the taps. The filter requires only a single laser source for all the taps and a passive component, a SM-to-MM combiner, for incoherent summing of signal. The SM-to-MM combiner does not produce optical interference during signal merging and is phase-insensitive. We experimentally demonstrate an eight-tap filter with both positive and negative programmable coefficients with excellent correspondence between predicted and measured values. The magnitude response shows a clean and accurate function across the entire bandwidth, and proves successful operation of the FIR filter using a SM-to-MM combiner.

  8. Reduction of NOx emission in tangential fired - furnace by changing the, mode of operation

    International Nuclear Information System (INIS)

    Chudnovsky, B.; Talanker, A.; Levin, L.; Kahana, S

    1998-01-01

    The present work analyses tile results of tests on 575 MW units with tangential firing furnace arrangement in sub-stoichiometric combustion. Tangential firing provides good conditions for implementing sub-stoichiometric combustion owing to the delivery scheme of pulverized coal and air. The furnace was tested in several different modes of operation (Over Fire Air, Bunkers Out Of Service, Excess air, Tilt etc.) to achieve low cost NOx reduction. Actual performance data are presented based on experiments made on lEC's boiler in M.D. 'B' power station

  9. Spectrum of single photon emission computed tomography/computed tomography findings in patients with parathyroid adenomas.

    Science.gov (United States)

    Chakraborty, Dhritiman; Mittal, Bhagwant Rai; Harisankar, Chidambaram Natrajan Balasubramanian; Bhattacharya, Anish; Bhadada, Sanjay

    2011-01-01

    Primary hyperparathyroidism results from excessive parathyroid hormone secretion. Approximately 85% of all cases of primary hyperparathyroidism are caused by a single parathyroid adenoma; 10-15% of the cases are caused by parathyroid hyperplasia. Parathyroid carcinoma accounts for approximately 3-4% of cases of primary disease. Technetium-99m-sestamibi (MIBI), the current scintigraphic procedure of choice for preoperative parathyroid localization, can be performed in various ways. The "single-isotope, double-phase technique" is based on the fact that MIBI washes out more rapidly from the thyroid than from abnormal parathyroid tissue. However, not all parathyroid lesions retain MIBI and not all thyroid tissue washes out quickly, and subtraction imaging is helpful. Single photon emission computed tomography (SPECT) provides information for localizing parathyroid lesions, differentiating thyroid from parathyroid lesions, and detecting and localizing ectopic parathyroid lesions. Addition of CT with SPECT improves the sensitivity. This pictorial assay demonstrates various SPECT/CT patterns observed in parathyroid scintigraphy.

  10. Surface plasmon modes of a single silver nanorod: An electron energy loss study

    DEFF Research Database (Denmark)

    Nicoletti, Olivia; Wubs, Martijn; Mortensen, N. Asger

    2011-01-01

    We present an electron energy loss study using energy filtered TEM of spatially resolved surface plasmon excitations on a silver nanorod of aspect ratio 14.2 resting on a 30 nm thick silicon nitride membrane. Our results show that the excitation is quantized as resonant modes whose intensity maxima...

  11. Experience with Aerosol Generation During Rotary Mode Core Sampling in the Hanford Single Shell Waste Tanks

    International Nuclear Information System (INIS)

    SCHOFIELD, J.S.

    2000-01-01

    This document provides data on aerosol concentrations in tank head spaces, total mass of aerosols in the tank head space and mass of aerosols sent to the exhauster during Rotary Mode Core Sampling from November 1994 through June 1999. A decontamination factor for the RMCS exhauster filter housing is calculated based on operation data

  12. Divertor power load studies for attached L-mode single-null plasmas in TCV

    NARCIS (Netherlands)

    Maurizio, R.; Elmore, S.; Fedorczak, N.; Gallo, A.; Reimerdes, H.; Labit, B.; Theiler, C.; Tsui, C. K.; Vijvers, W. A. J.; TCV team,; MST1 Team,

    2018-01-01

    This paper investigates the power loads at the inner and outer divertor targets of attached, Ohmic L-mode, deuterium plasmas in the TCV tokamak, in various experimental situations using an Infrared thermography system. The study comprises variations of the outer divertor leg length and target flux

  13. Enhanced single-photon emission from a diamond–silver aperture

    KAUST Repository

    Choy, Jennifer T.; Hausmann, Birgit J. M.; Babinec, Thomas M.; Bulu, Irfan; Khan, Mughees; Maletinsky, Patrick; Yacoby, Amir; Lončar, Marko

    2011-01-01

    Solid-state quantum emitters, such as the nitrogen-vacancy centre in diamond, are robust systems for practical realizations of various quantum information processing protocols2-5 and nanoscale magnetometry schemes6,7 at room temperature. Such applications benefit from the high emission efficiency and flux of single photons, which can be achieved by engineering the electromagnetic environment of the emitter. One attractive approach is based on plasmonic resonators8-13, in which sub-wavelength confinement of optical fields can strongly modify the spontaneous emission of a suitably embedded dipole despite having only modest quality factors. Meanwhile, the scalability of solid-state quantum systems critically depends on the ability to control such emitterg-cavity interaction in a number of devices arranged in parallel. Here, we demonstrate a method to enhance the radiative emission rate of single nitrogen-vacancy centres in ordered arrays of plasmonic apertures that promises greater scalability over the previously demonstrated bottom-up approaches for the realization of on-chip quantum networks. © 2011 Macmillan Publishers Limited. All rights reserved.

  14. Enhanced single-photon emission from a diamond–silver aperture

    KAUST Repository

    Choy, Jennifer T.

    2011-10-09

    Solid-state quantum emitters, such as the nitrogen-vacancy centre in diamond, are robust systems for practical realizations of various quantum information processing protocols2-5 and nanoscale magnetometry schemes6,7 at room temperature. Such applications benefit from the high emission efficiency and flux of single photons, which can be achieved by engineering the electromagnetic environment of the emitter. One attractive approach is based on plasmonic resonators8-13, in which sub-wavelength confinement of optical fields can strongly modify the spontaneous emission of a suitably embedded dipole despite having only modest quality factors. Meanwhile, the scalability of solid-state quantum systems critically depends on the ability to control such emitterg-cavity interaction in a number of devices arranged in parallel. Here, we demonstrate a method to enhance the radiative emission rate of single nitrogen-vacancy centres in ordered arrays of plasmonic apertures that promises greater scalability over the previously demonstrated bottom-up approaches for the realization of on-chip quantum networks. © 2011 Macmillan Publishers Limited. All rights reserved.

  15. Color optimization of single emissive white OLEDs via energy transfer between RGB fluorescent dopants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam Ho; Kim, You-Hyun; Yoon, Ju-An; Lee, Sang Youn [Department of Green Energy and Semiconductor Engineering, Hoseo University, Asan (Korea, Republic of); Ryu, Dae Hyun [Department of Information Technology, Hansei University, Gunpo (Korea, Republic of); Wood, Richard [Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada L8S 4L7 (Canada); Moon, C.-B. [Department of Green Energy and Semiconductor Engineering, Hoseo University, Asan (Korea, Republic of); Kim, Woo Young, E-mail: wykim@hoseo.edu [Department of Green Energy and Semiconductor Engineering, Hoseo University, Asan (Korea, Republic of); Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada L8S 4L7 (Canada)

    2013-11-15

    The electroluminescent characteristics of white organic light-emitting diodes (WOLEDs) were investigated including single emitting layer (SEL) with an ADN host and dopants; BCzVBi, C545T, and DCJTB for blue, green and red emission, respectively. The structure of the high efficiency WOLED device was; ITO/NPB(700 Å)/ADN: BCzVBi-7%:C545T-0.05%:DCJTB-0.1%(300 Å)/Bphen(300 Å)/Liq(20 Å)/Al(1200 Å) for mixing three primary colors. Luminous efficiency was 9.08 cd/A at 3.5 V and Commission Intenationale de L’eclairage (CIE{sub x,y}) coordinates of white emission was measured as (0.320, 0.338) at 8 V while simulated CIE{sub x,y} coordinates were (0.336, 0.324) via estimation from each dopant's PL spectrum. -- Highlights: • This paper observes single-emissive-layered white OLED using fluorescent dopants. • Electrical and optical properties are analyzed. • Color stability of white OLED is confirmed for new planar light source.

  16. Color optimization of single emissive white OLEDs via energy transfer between RGB fluorescent dopants

    International Nuclear Information System (INIS)

    Kim, Nam Ho; Kim, You-Hyun; Yoon, Ju-An; Lee, Sang Youn; Ryu, Dae Hyun; Wood, Richard; Moon, C.-B.; Kim, Woo Young

    2013-01-01

    The electroluminescent characteristics of white organic light-emitting diodes (WOLEDs) were investigated including single emitting layer (SEL) with an ADN host and dopants; BCzVBi, C545T, and DCJTB for blue, green and red emission, respectively. The structure of the high efficiency WOLED device was; ITO/NPB(700 Å)/ADN: BCzVBi-7%:C545T-0.05%:DCJTB-0.1%(300 Å)/Bphen(300 Å)/Liq(20 Å)/Al(1200 Å) for mixing three primary colors. Luminous efficiency was 9.08 cd/A at 3.5 V and Commission Intenationale de L’eclairage (CIE x,y ) coordinates of white emission was measured as (0.320, 0.338) at 8 V while simulated CIE x,y coordinates were (0.336, 0.324) via estimation from each dopant's PL spectrum. -- Highlights: • This paper observes single-emissive-layered white OLED using fluorescent dopants. • Electrical and optical properties are analyzed. • Color stability of white OLED is confirmed for new planar light source

  17. Diesel Combustion and Emission Using High Boost and High Injection Pressure in a Single Cylinder Engine

    Science.gov (United States)

    Aoyagi, Yuzo; Kunishima, Eiji; Asaumi, Yasuo; Aihara, Yoshiaki; Odaka, Matsuo; Goto, Yuichi

    Heavy-duty diesel engines have adopted numerous technologies for clean emissions and low fuel consumption. Some are direct fuel injection combined with high injection pressure and adequate in-cylinder air motion, turbo-intercooler systems, and strong steel pistons. Using these technologies, diesel engines have achieved an extremely low CO2 emission as a prime mover. However, heavy-duty diesel engines with even lower NOx and PM emission levels are anticipated. This study achieved high-boost and lean diesel combustion using a single cylinder engine that provides good engine performance and clean exhaust emission. The experiment was done under conditions of intake air quantity up to five times that of a naturally aspirated (NA) engine and 200MPa injection pressure. The adopted pressure booster is an external supercharger that can control intake air temperature. In this engine, the maximum cylinder pressure was increased and new technologies were adopted, including a monotherm piston for endurance of Pmax =30MPa. Moreover, every engine part is newly designed. As the boost pressure increases, the rate of heat release resembles the injection rate and becomes sharper. The combustion and brake thermal efficiency are improved. This high boost and lean diesel combustion creates little smoke; ISCO and ISTHC without the ISNOx increase. It also yields good thermal efficiency.

  18. Single-mode biological distributed feedback lasers based on vitamin B2 doped gelatin

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Maier-Flaig, F.; Lemmer, U.

    Biological second-order distributed feedback (DFB) lasers are presented. Riboflavin (vitamin B2) doped gelatin as active material is spin-coated onto nanoimprinted polymer with low refractive index. DFB grating periods of 368 nm and 384 nm yield laser emission at 543 nm and 562 nm, respectively....

  19. Development of radioiodinated receptor ligands for cerebral single photon emission tomography

    International Nuclear Information System (INIS)

    Knapp, F.F. Jr.; McPherson, D.W.

    1992-01-01

    In the last decade the use of radiolabeled ligands for the imaging of cerebral receptors by emission computed tomography (ECT) has seen rapid growth. The opportunity to routinely perform cerebral single photon emission tomography (SPET) with iodine-123-labeled ligands depends on the availability of receptor ligands into which iodine can be introduced without decreasing the required high target receptor specificity. The use of iodine-123-labeled receptor-specific ligands also depends on the availability of high purity iodine-123 at reasonable costs and the necessary imaging instrumentation. In this paper, the development and current stage of evaluation of various iodine-123-labeled ligands for SPET imaging of dopaminergic, serotonergic and muscarinic acetylcholinergic receptor classes are discussed

  20. First detection of nonflare microwave emissions from the coronae of single late-type dwarf stars

    Science.gov (United States)

    Gary, D. E.; Linsky, J. L.

    1981-01-01

    Results are presented of a search for nonflare microwave radiation from the coronae of nearby late-type dwarf stars comparable to the sun: single stars without evidence for either a large wind or circumstellar envelope. The observing program consisted of flux measurements of six stars over a 24-h period with the VLA in the C configuration at a wavelength of 6 cm with 50 MHz bandwidth. Positive detections at 6 cm were made for Chi 1 Ori (0.6 mJy) and the flare star UV Cet (1.55 mJy), and upper limits were obtained for the stars Pi 1 UMa, Xi Boo A, 70 Oph A and Epsilon Eri. It is suggested that Chi 1 Ori, and possibly UV Cet, represent the first detected members of a new class of radio sources which are driven by gyroresonance emission, i.e. cyclotron emission from nonrelativistic Maxwellian electrons.

  1. Single-photon emission associated with double electron capture in F9+ + C collisions

    CERN Document Server

    Elkafrawy, Tamer; Tanis, John A; Warczak, Andrzej

    2016-01-01

    Radiative double electron capture (RDEC), the one-step process occurring in ion-atom collisions, has been investigated for bare fluorine ions colliding with carbon. RDEC is completed when two target electrons are captured to a bound state of a projectile simultaneously with the emission of a single photon. This work is a follow-up to our earlier measurement of RDEC for bare oxygen projectiles, thus providing a recipient system free of electron-related Coulomb fields in both cases and allowing for the comparison between the two collision systems as well as with available theoretical studies. The most significant mechanisms of x-ray emission that may contribute to the RDEC energy region as background processes are also addressed.

  2. Aeration Strategies To Mitigate Nitrous Oxide Emissions from Single-Stage Nitritation/Anammox Reactors

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Mutlu, A. Gizem; Jensen, Marlene Mark

    2014-01-01

    Autotrophic nitrogen removal is regarded as a resource efficient process to manage nitrogen-rich residual streams. However, nitrous oxide emissions of these processes are poorly documented and strategies to mitigate emissions unknown. In this study, two sequencing batch reactors performing single...... was noted when the duration of aeration was increased while decreasing air flow rate (10.9 +/- 3.2% Delta N2O/Delta TN). The extant ammonium oxidation activity (mgNH(4)(+)-N/gVSS.min) positively correlated with the specific N2O production rate (mgN(2)O-N/gVSS.min) of the systems. Operating under conditions......-stage nitritation/anammox were operated under different aeration strategies, gradually adjusted over six months. At constant but limiting oxygen loading, synthetic reject water was fed (0.75g-N/L.d) and high nitrogen removal efficiencies (83 +/- 5 and 88 +/- 2%) obtained. Dynamics of liquid phase nitrous (N2O...

  3. Single-photon emission computed tomography in the clinical evaluation of dementia

    International Nuclear Information System (INIS)

    Jagust, W.J.; Reed, B.R.; Budinger, T.F.; Colina, M.

    1987-01-01

    Physiological imaging using positron emission tomography (PET) has been a useful tool in the investigation of dementia. In particular, patterns of cerebral glucose utilization appear to differentiate various types of dementia, with Alzheimer's disease (AD) demonstrating a propensity for hypometabolism to involve the temporoparietal cortex. Single-photon emission computed tomography (SPECT) using new tracers for the measurement of regional cerebral blood flow is a technique with potentially broader clinical availability than PET and thus may provide a practical method of routinely evaluating patients. The authors studied eight patients with AD, four healthy elderly controls, and one patient with multi-infarct dementia (MID) using the tracer 123 I-N-isopropyl-p-iodoamphetamine with SPECT

  4. Origin of yellow emission in white OLED with single emitting material

    Energy Technology Data Exchange (ETDEWEB)

    Akimoto, Ikuko; Tsuzuki, Sayaka; Uzawa, Hidetoshi; Hinatsu, Masako; Nishide, Yosuke; Osuga, Hideji; Sakamoto, Hidefumi [Faculty of Systems Engineering, Wakayama University, Sakaedani 930, Wakayama 640-8510 (Japan)

    2011-01-15

    The photo-luminescence (PL) and electro-luminescence (EL) of a novel organic material, benzodithiophene/triphenylamine copolymer (P-PBTx, n=5-6) were investigated. The PL exhibited wide blue emission at room temperature, which is attributed to fluorescence from a chromophore, benzodithiophene moiety, from results of spectral analysis and decay profile. The EL, however, exhibited white emission consisting of wide blue (B) and yellow (Y) bands, although it was prepared with P-PBTx as a single emitting material. The Y-band was slightly observed at 7 K and found to possess long lived component of 19 ms lifetime. The origin of the Y-band efficiently stimulated by carrier injection is supposed to be a charge-transfer state between benzodithiophene and triphenylamine moieties. The long lived component could be explained by lowered transition probability caused by charge separation. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Science.gov (United States)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-08-01

    We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester Cdbnd O and diazo Ndbnd N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency-frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single Cdbnd O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  6. A safety equipment list for rotary mode core sampling systems operation in single shell flammable gas tanks; TOPICAL

    International Nuclear Information System (INIS)

    SMALLEY, J.L.

    1999-01-01

    This document identifies all interim safety equipment to be used for rotary mode core sampling of single-shell flammable gas tanks utilizing Rotary Mode Core Sampling systems (RMCS). This document provides the safety equipment for RMCS trucks HO-68K-4600, HO-68K-4647, trucks three and four respectively, and associated equipment. It is not intended to replace or supersede WHC-SD-WM-SEL-023, (Kelly 1991), or WHC-SD-WM-SEL-032, (Corbett 1994), which classifies 80-68K-4344 and HO-68K-4345 respectively. The term ''safety equipment'' refers to safety class (SC) and safety significant (SS) equipment, where equipment refers to structures, systems and components (SSC's). The identification of safety equipment in this document is based on the credited design safety features and analysis contained in the Authorization Basis (AB) for rotary mode core sampling operations in single-shell flammable gas tanks. This is an interim safety classification since the AB is interim. This document will be updated to reflect the final RMCS equipment safety classification designations upon completion of a final AB which will be implemented with the release of the Final Safety Analysis Report (FSAR)

  7. The quantum dynamics of two qubits inside two distant microcavities connected via a single-mode optical fiber

    International Nuclear Information System (INIS)

    Nguyen, Van Hieu; Nguyen, Bich Ha; Duong, Hai Trieu

    2010-01-01

    For application to studying the transmission of quantum information, also called quantum communication, between two identical qubits placed inside two identical single-mode microcavities connected via a single-mode optical fiber, the time evolution of this system is investigated. In the Markovian approximation, the von Neumann equation for its reduced density matrix contains a completely positive linear operator called the Liouvillian operator describing the decoherence of this system due to its interaction with the environment. By using the Linblad formula for the Liouvillian operator, a system of rate equations can be derived. In the special case of resonance between the energy difference of two states in each qubit and the energy of the fiber mode, the rate equations for the system excited up to the first level are solved in first order approximation with respect to the decoherence constants. It is shown that when there is no decoherence, the perfect quantum state transmission between two qubits can take place if the physical parameters of the system satisfy definite conditions. A possible extension to studying the system excited to high energy states is also discussed

  8. A safety equipment list for rotary mode core sampling systems operation in single shell flammable gas tanks

    International Nuclear Information System (INIS)

    SMALLEY, J.L.

    1999-01-01

    This document identifies all interim safety equipment to be used for rotary mode core sampling of single-shell flammable gas tanks utilizing Rotary Mode Core Sampling systems (RMCS). This document provides the safety equipment for RMCS trucks HO-68K-4600, HO-68K-4647, trucks three and four respectively, and associated equipment. It is not intended to replace or supersede WHC-SD-WM-SEL-023, (Kelly 1991), or WHC-SD-WM-SEL-032, (Corbett 1994), which classifies 80-68K-4344 and HO-68K-4345 respectively. The term ''safety equipment'' refers to safety class (SC) and safety significant (SS) equipment, where equipment refers to structures, systems and components (SSC's). The identification of safety equipment in this document is based on the credited design safety features and analysis contained in the Authorization Basis (AB) for rotary mode core sampling operations in single-shell flammable gas tanks. This is an interim safety classification since the AB is interim. This document will be updated to reflect the final RMCS equipment safety classification designations upon completion of a final AB which will be implemented with the release of the Final Safety Analysis Report (FSAR)

  9. Signal Processing using Nonlinear Optical Eects in Single- and Few-Mode Fibers

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk

    noise, loss, and pump depletion on the noise properties of parametric frequency conversion and phase-insensitive and phase-sensitive parametric amplification. An important part of realizing space-division multiplexing is the ability of optical signal processing so the second part of this thesis......-wave mixing in two-mode fibers acvi counting for six simultaneous processes is derived, and the conversion efficiency from signal to idler in the four-wave mixing processes of phase conjugation and Bragg scattering in two two-mode fibers with different phase matching properties are experimentally investigated......The stagnating increase in data transmission capacity in optical communication systems combined with the ever growing demand of transmission bandwidth is leading to an impending capacity crunch, referring to the point in time after which the available bandwidth of the individual user starts...

  10. Phonon self-energy corrections to non-zero wavevector phonon modes in single-layer graphene

    Science.gov (United States)

    Araujo, Paulo; Mafra, Daniela; Sato, Kentaro; Saito, Richiiro; Kong, Jing; Dresselhaus, Mildred

    2012-02-01

    Phonon self-energy corrections have mostly been studied theoretically and experimentally for phonon modes with zone-center (q = 0) wave-vectors. Here, gate-modulated Raman scattering is used to study phonons of a single layer of graphene (1LG) in the frequency range from 2350 to 2750 cm-1, which shows the G* and the G'-band features originating from a double-resonant Raman process with q 0. The observed phonon renormalization effects are different from what is observed for the zone-center q = 0 case. To explain our experimental findings, we explored the phonon self-energy for the phonons with non-zero wave-vectors (q 0) in 1LG in which the frequencies and decay widths are expected to behave oppositely to the behavior observed in the corresponding zone-center q = 0 processes. Within this framework, we resolve the identification of the phonon modes contributing to the G* Raman feature at 2450 cm-1 to include the iTO+LA combination modes with q 0 and the 2iTO overtone modes with q = 0, showing both to be associated with wave-vectors near the high symmetry point K in the Brillouin zone.

  11. Single-mode saturation of the bump-on-tail instability

    International Nuclear Information System (INIS)

    Simon, A.; Rosenbluth, M.N.

    1976-01-01

    A slightly unstable plasma with only one or a few linear modes unstable is considered. Nonlinear saturation at small amplitudes has been treated by time-asymptotic analysis which is a generalization of the methods of Bogolyubov and co-workers. In this paper the method is applied to instability in a collisionless plasma governed by the vlasov equation. The bump-on-tail instability is considered for a one-dimensional plasma

  12. Fully 3-D list-mode positron emission tomography image reconstruction on a multi-GPU cluster

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jingyu [Stanford Univ., CA (United States). Dept. of Electrical Engineering; Prevrhal, Sven; Shao, Lingxiong [Philips Healthcare, San Jose, CA (United States); Pratx, Guillem [Stanford Univ., CA (United States). Dept. of Radiation Oncology; Levin, Craig S. [Stanford Univ., CA (United States). Dept. of Radiology, Electrical Engineering, and Physics; Stanford Univ., CA (United States). Molecular Imaging Program at Stanford (MIPS); Stanford Univ., CA (United States). School of Medicine

    2011-07-01

    List-mode processing is an efficient way of dealing with the sparse nature of PET data sets, and is the processing method of choice for time-of-flight (ToF) PET. We present a novel method of computing line projection operations required for list-mode ordered subsets expectation maximization (OSEM) for fully 3-D PET image reconstruction on a graphics processing unit (GPU) using the compute unified device architecture (CUDA) framework. Our method overcomes challenges such as compute thread divergence, and exploits GPU capabilities such as shared memory and atomic operations. When applied to line projection operations for list-mode time-of-flight PET, this new GPU-CUDA reformulation is 188X faster than a single-threaded reference CPU implementation. When embedded in a multi-process environment on a GPU-equipped small cluster, a speedup of 4X was observed over the same configuration but without GPU support. Image quality is preserved with root mean squared (RMS) deviation of 0.05% between CPU and GPU-generated images, which has negligible effect in typical clinical applications. (orig.)

  13. Transition of lasing modes in polymeric opal photonic crystal resonating cavity.

    Science.gov (United States)

    Shi, Lan-Ting; Zheng, Mei-Ling; Jin, Feng; Dong, Xian-Zi; Chen, Wei-Qiang; Zhao, Zhen-Sheng; Duan, Xuan-Ming

    2016-06-10

    We demonstrate the transition of lasing modes in the resonating cavity constructed by polystyrene opal photonic crystals and 7 wt. % tert-butyl Rhodamine B doped polymer film. Both single mode and multiple mode lasing emission are observed from the resonating cavity. The lasing threshold is determined to be 0.81  μJ/pulse for single mode lasing emission and 2.25  μJ/pulse for multiple mode lasing emission. The single mode lasing emission is attributed to photonic lasing resulting from the photonic bandgap effect of the opal photonic crystals, while the multiple mode lasing emission is assigned to random lasing due to the defects in the photonic crystals. The result would benefit the development of low threshold polymeric solid state photonic crystal lasers.

  14. Nonlinear Phenomena in the Single-Mode Dynamics in an AFM Cantilever Beam

    KAUST Repository

    Ruzziconi, Laura; Lenci, Stefano; Younis, Mohammad I.

    2016-01-01

    This study deals with the nonlinear dynamics arising in an atomic force microscope cantilever beam. After analyzing the static behavior, a single degree of freedom Galerkin reduced order model is introduced, which describes the overall scenario

  15. Seismic response of elastically restrained single bellows expansion joint in lateral mode

    International Nuclear Information System (INIS)

    Kameswara Rao, C.; Radhakrishna, M.

    2003-01-01

    The present paper attempts to derive an exact solution for the seismic response of U type of single bellows that are considered elastically restrained against rotation to classical fixed-fixed case considered by Morishita et al. (author)

  16. Cyclotron Acceleration of Relativistic Electrons through Landau Resonance with Obliquely Propagating Whistler Mode Chorus Emissions

    Science.gov (United States)

    Omura, Y.; Hsieh, Y. K.; Foster, J. C.; Erickson, P. J.; Kletzing, C.; Baker, D. N.

    2017-12-01

    A recent test particle simulation of obliquely propagating whistler mode wave-particle interaction [Hsieh and Omura, 2017] shows that the perpendicular wave electric field can play a significant role in trapping and accelerating relativistic electrons through Landau resonance. A further theoretical and numerical investigation verifies that there occurs nonlinear wave trapping of relativistic electrons by the nonlinear Lorentz force of the perpendicular wave magnetic field. An electron moving with a parallel velocity equal to the parallel phase velocity of an obliquely propagating wave basically see a stationary wave phase. Since the electron position is displaced from its gyrocenter by a distance ρ*sin(φ), where ρ is the gyroradius and φ is the gyrophase, the wave phase is modulated with the gyromotion, and the stationary wave fields as seen by the electron are expanded as series of Bessel functions Jn with phase variations n*φ. The J1 components of the wave electric and magnetic fields rotate in the right-hand direction with the gyrofrequency, and they can be in resonance with the electron undergoing the gyromotion, resulting in effective electron acceleration and pitch angle scattering. We have performed a subpacket analysis of chorus waveforms observed by the Van Allen Probes [Foster et al., 2017], and calculated the energy gain by the cyclotron acceleration through Landau resonance. We compare the efficiencies of accelerations by cyclotron and Landau resonances in typical events of rapid electron acceleration observed by the Van Allen Probes.References:[1] Hsieh, Y.-K., and Y. Omura (2017), Nonlinear dynamics of electrons interacting with oblique whistler mode chorus in the magnetosphere, J. Geophys. Res. Space Physics, 122, 675-694, doi:10.1002/2016JA023255.[2] Foster, J. C., P. J. Erickson, Y. Omura, D. N. Baker, C. A. Kletzing, and S. G. Claudepierre (2017), Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear

  17. Hard photon emission from high energy electrons and positrons in single crystals

    International Nuclear Information System (INIS)

    Bajer, V.N.; Katkov, V.M.; Strakhovenko, V.M.

    1991-01-01

    A radiation of electrons and positrons in single crystals in coherent bremsstrahlung (CBS) region has been considered for the case when CBS has the most hard spectrum. Under this condition a particle moves near a crystalline plane (in fcc(d) crystal for axis (001) this is the plane (110)) and influence of the continuous plane potential should be taken into account. This potential gives additional contribution in soft part of the spectrum and affects on hard photon emission. Observation of this phenomena at high energy is discussed. 14 refs.; 5 figs.; 1 tab

  18. Left ventricular volume determination from single-photon emission computed tomography

    International Nuclear Information System (INIS)

    Bunker, S.R.; Hartshorne, M.F.; Schmidt, W.P.; Cawthon, M.A.; Karl, R.D. Jr.; Bauman, J.M.; Howard, W.H. III; Rubal, B.J.

    1985-01-01

    To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterizaiton for coronary artery or valvular heart disease were first evaluated scintigraphically. SPECT volume values showed a high degree of correlation with those determined by angiography with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting

  19. Left ventricular volume determination from single-photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bunker, S.R.; Hartshorne, M.F.; Schmidt, W.P.; Cawthon, M.A.; Karl, R.D. Jr.; Bauman, J.M.; Howard, W.H. III; Rubal, B.J.

    1985-02-01

    To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterizaiton for coronary artery or valvular heart disease were first evaluated scintigraphically. SPECT volume values showed a high degree of correlation with those determined by angiography with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting.

  20. Painful spondylolysis or spondylolisthesis studied by radiography and single-photon emission computed tomography

    International Nuclear Information System (INIS)

    Collier, B.D.; Johnson, R.P.; Carrera, G.F.

    1985-01-01

    Planar bone scintigraphy (PBS) and single-photon emission computed tomography (SPECT) were compared in 19 adults with radiographic evidence of spondylolysis and/or spondylolisthesis. SPECT was more sensitive than PBS when used to identify symptomatic patients and sites of painful defects in the pars interarticularis. In addition, SPECT allowed more accurate localization than PBS. In 6 patients, spondylolysis or spondylolisthesis was unrealted to low back pain, and SPECT images of the posterior neural arch were normal. The authors conclude that when spondylolysis or spondylolisthesis is the cause of low back pain, pars defects are frequently heralded by increased scintigraphic activity which is best detected and localized by SPECT

  1. Painful spondylolysis or spondylolisthesis studied by radiography and single-photon emission computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Collier, B.D.; Johnson, R.P.; Carrera, G.F.; Meyer, G.A.; Schwab, J.P.; Flatley, T.J.; Isitman, A.T.; Hellman, R.S.; Zielonka, J.S.; Knobel, J.

    1985-01-01

    Planar bone scintigraphy (PBS) and single-photon emission computed tomography (SPECT) were compared in 19 adults with radiographic evidence of spondylolysis and/or spondylolisthesis. SPECT was more sensitive than PBS when used to identify symptomatic patients and sites of painful defects in the pars interarticularis. In addition, SPECT allowed more accurate localization than PBS. In 6 patients, spondylolysis or spondylolisthesis was unrealted to low back pain, and SPECT images of the posterior neural arch were normal. The authors conclude that when spondylolysis or spondylolisthesis is the cause of low back pain, pars defects are frequently heralded by increased scintigraphic activity which is best detected and localized by SPECT.

  2. Bronchobiliary Fistula Localized by Cholescintigraphy with Single-Photon Emission Computed Tomography

    International Nuclear Information System (INIS)

    Artunduaga, Maddy; Patel, Niraj R.; Wendt, Julie A.; Guy, Elizabeth S.; Nachiappan, Arun C.

    2015-01-01

    Biliptysis is an important clinical feature to recognize as it is associated with bronchobiliary fistula, a rare entity. Bronchobiliary fistulas have been diagnosed with planar cholescintigraphy. However, cholescintigraphy with single-photon emission computed tomography (SPECT) can better spatially localize a bronchobiliary fistula as compared to planar cholescintigraphy alone, and is useful for preoperative planning if surgical treatment is required. Here, we present the case of a 23-year-old male who developed a bronchobiliary fistula in the setting of posttraumatic and postsurgical infection, which was diagnosed and localized by cholescintigraphy with SPECT

  3. An analysis of regional cerebral blood flow in impulsive murderers using single photon emission computed tomography.

    Science.gov (United States)

    Amen, Daniel G; Hanks, Chris; Prunella, Jill R; Green, Aisa

    2007-01-01

    The authors explored differences in regional cerebral blood flow in 11 impulsive murderers and 11 healthy comparison subjects using single photon emission computed tomography. The authors assessed subjects at rest and during a computerized go/no-go concentration task. Using statistical parametric mapping software, the authors performed voxel-by-voxel t tests to assess significant differences, making family-wide error corrections for multiple comparisons. Murderers were found to have significantly lower relative rCBF during concentration, particularly in areas associated with concentration and impulse control. These results indicate that nonemotionally laden stimuli may result in frontotemporal dysregulation in people predisposed to impulsive violence.

  4. Photon emission statistics and photon tracking in single-molecule spectroscopy of molecular aggregates : Dimers and trimers

    NARCIS (Netherlands)

    Bloemsma, E. A.; Knoester, J.

    2012-01-01

    Based on the generating function formalism, we investigate broadband photon statistics of emission for single dimers and trimers driven by a continuous monochromatic laser field. In particular, we study the first and second moments of the emission statistics, which are the fluorescence excitation

  5. On the excess photon noise in single-beam measurements with photo-emissive and photo-conductive cells

    NARCIS (Netherlands)

    Alkemade, C.T.J.

    In this paper the so-called excess photon noise is theoretically considered with regard to noise power measurements with a single, illumined photo-emissive or photo-conductive cell. Starting from a modification of Mandel's stochastic association of the emission of photo-electrons with wave

  6. Impacts of fleet types and charging modes for electric vehicles on emissions under different penetrations of wind power

    Science.gov (United States)

    Chen, Xinyu; Zhang, Hongcai; Xu, Zhiwei; Nielsen, Chris P.; McElroy, Michael B.; Lv, Jiajun

    2018-05-01

    Current Chinese policy promotes the development of both electricity-propelled vehicles and carbon-free sources of power. Concern has been expressed that electric vehicles on average may emit more CO2 and conventional pollutants in China. Here, we explore the environmental implications of investments in different types of electric vehicle (public buses, taxis and private light-duty vehicles) and different modes (fast or slow) for charging under a range of different wind penetration levels. To do this, we take Beijing in 2020 as a case study and employ hourly simulation of vehicle charging behaviour and power system operation. Assuming the slow-charging option, we find that investments in electric private light-duty vehicles can result in an effective reduction in the emission of CO2 at several levels of wind penetration. The fast-charging option, however, is counter-productive. Electrifying buses and taxis offers the most effective option to reduce emissions of NOx, a major precursor for air pollution.

  7. Multistabilities and symmetry-broken one-color and two-color states in closely coupled single-mode lasers.

    Science.gov (United States)

    Clerkin, Eoin; O'Brien, Stephen; Amann, Andreas

    2014-03-01

    We theoretically investigate the dynamics of two mutually coupled, identical single-mode semi-conductor lasers. For small separation and large coupling between the lasers, symmetry-broken one-color states are shown to be stable. In this case the light outputs of the lasers have significantly different intensities while at the same time the lasers are locked to a single common frequency. For intermediate coupling we observe stable symmetry-broken two-color states, where both lasers lase simultaneously at two optical frequencies which are separated by up to 150 GHz. Using a five-dimensional model, we identify the bifurcation structure which is responsible for the appearance of symmetric and symmetry-broken one-color and two-color states. Several of these states give rise to multistabilities and therefore allow for the design of all-optical memory elements on the basis of two coupled single-mode lasers. The switching performance of selected designs of optical memory elements is studied numerically.

  8. Assessment of left ventricular function by electrocardiogram-gated myocardial single photon emission computed tomography using quantitative gated single photon emission computed tomography software

    International Nuclear Information System (INIS)

    Morita, Koichi; Adachi, Itaru; Konno, Masanori

    1999-01-01

    Electrocardiogram (ECG)-gated myocardial single photon emission computed tomography (SPECT) can assess left ventricular (LV) perfusion and function easily using quantitative gated SPECT (QGS) software. ECG-gated SPECT was performed in 44 patients with coronary artery disease under post-stress and resting conditions to assess the values of LV functional parameters, by comparison to LV ejection fraction derived from gated blood pool scan and myocardial characteristics. A good correlation was obtained between ejection fraction using QGS and that using cardiac blood pool scan (r=0.812). Some patients with myocardial ischemia had lower ejection fraction under post-stress compared to resting conditions, indicating post-stress LV dysfunction. LV wall motion and wall thickening were significantly impaired in ischemic and infarcted myocardium, and the degree of abnormality in the infarcted areas was greater than in the ischemia area. LV functional parameters derived using QGS were useful to assess post-stress LV dysfunction and myocardial viability. In conclusion, ECG-gated myocardial SPECT permits simultaneous quantitative assessment of myocardial perfusion and function. (author)

  9. Interannual variation in the fine-mode MODIS aerosol optical depth and its relationship to the changes in sulfur dioxide emissions in China between 2000 and 2010

    Directory of Open Access Journals (Sweden)

    S. Itahashi

    2012-03-01

    Full Text Available Anthropogenic SO2 emissions increased alongside economic development in China at a rate of 12.7% yr−1 from 2000 to 2005. However, under new Chinese government policy, SO2 emissions declined by 3.9% yr−1 between 2005 and 2009. Between 2000 and 2010, we found that the variability in the fine-mode (submicron aerosol optical depth (AOD over the oceans adjacent to East Asia increased by 3–8% yr−1 to a peak around 2005–2006 and subsequently decreased by 2–7% yr−1, based on observations by the Moderate Resolution Imaging Spectroradiometer (MODIS on board NASA's Terra satellite and simulations by a chemical transport model. This trend is consistent with ground-based observations of aerosol particles at a mountainous background observation site in central Japan. These fluctuations in SO2 emission intensity and fine-mode AOD are thought to reflect the widespread installation of fuel-gas desulfurization (FGD devices in power plants in China, because aerosol sulfate is a major determinant of the fine-mode AOD in East Asia. Using a chemical transport model, we confirmed that the contribution of particulate sulfate to the fine-mode AOD is more than 70% of the annual mean and that the abovementioned fluctuation in fine-mode AOD is caused mainly by changes in SO2 emission rather than by other factors such as varying meteorological conditions in East Asia. A strong correlation was also found between satellite-retrieved SO2 vertical column density and bottom-up SO2 emissions, both of which were also consistent with observed fine-mode AOD trends. We propose a simplified approach for evaluating changes in SO2 emissions in China, combining the use of modeled sensitivity coefficients that describe the variation of fine-mode AOD with changes in SO2 emissions and satellite retrieval. Satellite measurements of fine-mode AOD

  10. Electrical manipulation of the light emission of single CdSe/CdS nanorods

    International Nuclear Information System (INIS)

    Mueller, J.

    2005-01-01

    In the center of the present thesis lies the study and manipulation of the light emission of novel rod-shaped cadmium-selenide/cadmium-sulfide (CdSe/CdS) nanocrystals. These nanocrystals consist of a spherical CdSe nucleus, on which a CdS nanorod is grown monocrystallinely. By this grow spatially asymmetric semiconductor nanorods with an aspect ratio between 1.6 and 4.0. By the measurement of the radiation rate in this thesis it could be shown that the electron is delocalized over the whole nanorod, while the hole is localized in the CdSe nucleus. Therefore by the length of the cadmium-sulfide rod the wave-function overlap can be directly manipulated. The wave functions and by this the emission energies can be beside the geometry especially also controlled by external fields. Because the magnitude of the so-called ''Stark effect in quantum-bounded structures'' increases with the spatial extension of the nanostructure, in the nanorods an in comparison with spherical nanocrystals distinctly increased field effect could be observed. Experiments on single CdSe/CdS nanorods exhibit however not only a shift of the emission energy by the 50-fold of the line width, but simultaneously a field-induced decreasement of the emission intensity by one order of magnitude. The experimental results can be excellently compared with a theoretical model. For this the effective-mass model was supplemented by the Coulomb interaction and extended by a finite-element method for asymmetric geometries. By this it is possible to predict both the radiation rate, the Stark shift of the emission energy, and the intensity modulation by electric fields qualitatively and quantitatively and to describe the Stark effect in colloidal nanocrystal by a quantum-mechanical model. The emission characteristics is not only influenced by external fields, but also by fluctuations of local fields, which arise by diffunding surface charges. These local field changes induce also a Stark shift and lead to a time

  11. Sliding-mode control of single input multiple output DC-DC converter

    Science.gov (United States)

    Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

    2016-10-01

    Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage DC bus and middle-voltage output terminals, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

  12. Failure mode analysis in adrenal vein sampling: a single-center experience.

    Science.gov (United States)

    Trerotola, Scott O; Asmar, Melissa; Yan, Yan; Fraker, Douglas L; Cohen, Debbie L

    2014-10-01

    To analyze failure modes in a high-volume adrenal vein sampling (AVS) practice in an effort to identify preventable causes of nondiagnostic sampling. A retrospective database was constructed containing 343 AVS procedures performed over a 10-year period. Each nondiagnostic AVS procedure was reviewed for failure mode and correlated with results of any repeat AVS. Data collected included selectivity index, lateralization index, adrenalectomy outcomes if performed, and details of AVS procedure. All AVS procedures were performed after cosyntropin stimulation, using sequential technique. AVS was nondiagnostic in 12 of 343 (3.5%) primary procedures and 2 secondary procedures. Failure was right-sided in 8 (57%) procedures, left-sided in 4 (29%) procedures, bilateral in 1 procedure, and neither in 1 procedure (laboratory error). Failure modes included diluted sample from correctly identified vein (n = 7 [50%]; 3 right and 4 left), vessel misidentified as adrenal vein (n = 3 [21%]; all right), failure to locate an adrenal vein (n = 2 [14%]; both right), cosyntropin stimulation failure (n = 1 [7%]; diagnostic by nonstimulated criteria), and laboratory error (n = 1 [7%]; specimen loss). A second AVS procedure was diagnostic in three of five cases (60%), and a third AVS procedure was diagnostic in one of one case (100%). Among the eight patients in whom AVS ultimately was not diagnostic, four underwent adrenalectomy based on diluted AVS samples, and one underwent adrenalectomy based on imaging; all five experienced improvement in aldosteronism. A substantial percentage of AVS failures occur on the left, all related to dilution. Even when technically nondiagnostic per strict criteria, some "failed" AVS procedures may be sufficient to guide therapy. Repeat AVS has a good yield. Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.

  13. Studies of left ventricular volume estimation from single photon emission computed tomography

    International Nuclear Information System (INIS)

    Hiraki, Yoshio; Shimizu, Mitsuharu; Joja, Ikuo; Aono, Kaname; Yanagi, Hidekiyo; Indo, Haruaki; Seno, Yoshimasa; Teramoto, Shigeru; Nagaya, Isao.

    1988-01-01

    We studied the comparative accuracy of 99m Tc cardiac blood pool Single Photon Emission Computed Tomography (SPECT) for the measurement of left ventricular volume in 20 patients undergoing SPECT and single plane contrast left ventriculography (LVG). Left ventricular volume was calculated based on the total number of voxels in left ventricle. End-diastolic left ventricular volume (EDV) and end-systolic left ventricular volume (ESV) calculated from SPECT were compared with those from LVG. SPECT volume values showed a high degree of correlation with those by LVG (r = 0.923 for EDV, r = 0.903 for ESV). We appreciated the usefulness and accuracy of SPECT in measuring left ventricular volume because of its three-dimensional information. (author)

  14. Evaluation of scatter correction using a single isotope for simultaneous emission and transmission data

    International Nuclear Information System (INIS)

    Yang, J.; Kuikka, J.T.; Vanninen, E.; Laensimies, E.; Kauppinen, T.; Patomaeki, L.

    1999-01-01

    Photon scatter is one of the most important factors degrading the quantitative accuracy of SPECT images. Many scatter correction methods have been proposed. The single isotope method was proposed by us. Aim: We evaluate the scatter correction method of improving the quality of images by acquiring emission and transmission data simultaneously with single isotope scan. Method: To evaluate the proposed scatter correction method, a contrast and linearity phantom was studied. Four female patients with fibromyalgia (FM) syndrome and four with chronic back pain (BP) were imaged. Grey-to-cerebellum (G/C) and grey-to-white matter (G/W) ratios were determined by one skilled operator for 12 regions of interest (ROIs) in each subject. Results: The linearity of activity response was improved after the scatter correction (r=0.999). The y-intercept value of the regression line was 0.036 (p [de

  15. The incidence angle influence on the structure of secondary-emission characteristics of single crystals

    International Nuclear Information System (INIS)

    Gasanov, E.R.; Aliyev, B.Z.

    2012-01-01

    Full text : The dependences of Wand MO single crystals in different atom planes have been studied in this work. It is revealed that maximums are added to each dependency and also minimums of first and second degree. This fact is explained by diffraction dynamic theory. It is established that electron diffraction oriented not perpendicularly to crystal surface is the reason of appearance of second order structure on studied secondary-emission characteristics. In the present work being the continuation and development of SEE investigations of high-melting metal single crystals begun earlier by authors, the structure dependence of SEE main characteristics of angle has been studied. This angle has been chosen because as it is mentioned before the bad repeatability in different experiments for it is observed

  16. Position Control of the Single Spherical Wheel Mobile Robot by Using the Fuzzy Sliding Mode Controller

    OpenAIRE

    Hamed Navabi; Soroush Sadeghnejad; Sepehr Ramezani; Jacky Baltes

    2017-01-01

    A spherical wheel robot or Ballbot—a robot that balances on an actuated spherical ball—is a new and recent type of robot in the popular area of mobile robotics. This paper focuses on the modeling and control of such a robot. We apply the Lagrangian method to derive the governing dynamic equations of the system. We also describe a novel Fuzzy Sliding Mode Controller (FSMC) implemented to control a spherical wheel mobile robot. The nonlinear nature of the equations makes the controller nontrivi...

  17. Thermal Effects on the Single-Mode Regime of Distributed Modal Filtering Rod Fiber

    DEFF Research Database (Denmark)

    Coscelli, Enrico; Poli, Federica; Alkeskjold, Thomas Tanggaard

    2012-01-01

    Power scaling of fiber laser systems requires the development of innovative active fibers, capable of providing high pump absorption, ultralarge effective area, high-order mode suppression, and resilience to thermal effects. Thermally induced refractive index change has been recently appointed...... as one major limitation to the achievable power, causing degradation of the modal properties and preventing to obtain stable diffraction-limited output beam. In this paper, the effects of thermally induced refractive index change on the guiding properties of a double-cladding distributed modal filtering...

  18. High-performance imaging of stem cells using single-photon emissions

    Science.gov (United States)

    Wagenaar, Douglas J.; Moats, Rex A.; Hartsough, Neal E.; Meier, Dirk; Hugg, James W.; Yang, Tang; Gazit, Dan; Pelled, Gadi; Patt, Bradley E.

    2011-10-01

    Radiolabeled cells have been imaged for decades in the field of autoradiography. Recent advances in detector and microelectronics technologies have enabled the new field of "digital autoradiography" which remains limited to ex vivo specimens of thin tissue slices. The 3D field-of-view (FOV) of single cell imaging can be extended to millimeters if the low energy (10-30 keV) photon emissions of radionuclides are used for single-photon nuclear imaging. This new microscope uses a coded aperture foil made of highly attenuating elements such as gold or platinum to form the image as a kind of "lens". The detectors used for single-photon emission microscopy are typically silicon detectors with a pixel pitch less than 60 μm. The goal of this work is to image radiolabeled mesenchymal stem cells in vivo in an animal model of tendon repair processes. Single-photon nuclear imaging is an attractive modality for translational medicine since the labeled cells can be imaged simultaneously with the reparative processes by using the dual-isotope imaging technique. The details our microscope's two-layer gold aperture and the operation of the energy-dispersive, pixellated silicon detector are presented along with the first demonstration of energy discrimination with a 57Co source. Cell labeling techniques have been augmented by genetic engineering with the sodium-iodide symporter, a type of reporter gene imaging method that enables in vivo uptake of free 99mTc or an iodine isotope at a time point days or weeks after the insertion of the genetically modified stem cells into the animal model. This microscopy work in animal research may expand to the imaging of reporter-enabled stem cells simultaneously with the expected biological repair process in human clinical trials of stem cell therapies.

  19. Single-shot readout of accumulation mode Si/SiGe spin qubits using RF reflectometry

    Science.gov (United States)

    Volk, Christian; Martins, Frederico; Malinowski, Filip; Marcus, Charles M.; Kuemmeth, Ferdinand

    Spin qubits based on gate-defined quantum dots are promising systems for realizing quantum computation. Due to their low concentration of nuclear-spin-carrying isotopes, Si/SiGe heterostructures are of particular interest. While high fidelities have been reported for single-qubit and two-qubit gate operations, qubit initialization and measurement times are relatively slow. In order to develop fast read-out techniques compatible with the operation of spin qubits, we characterize double and triple quantum dots confined in undoped Si/Si0.7Ge0.3 heterostructures using accumulation and depletion gates and a nearby RF charge sensor dot. We implement a RF reflectometry technique that allows single-shot charge read-out at integration times on the order of a few μs. We show our recent advancement towards implementing spin qubits in these structures, including spin-selective single-shot read-out.

  20. Threshold and maximum power evolution of stimulated Brillouin scattering and Rayleigh backscattering in a single mode fiber segment

    International Nuclear Information System (INIS)

    Sanchez-Lara, R; Alvarez-Chavez, J A; Mendez-Martinez, F; De la Cruz-May, L; Perez-Sanchez, G G

    2015-01-01

    The behavior of stimulated Brillouin scattering (SBS) and Rayleigh backscattering phenomena, which limit the forward transmission power in modern, ultra-long haul optical communication systems such as dense wavelength division multiplexing systems is analyzed via simulation and experimental investigation of threshold and maximum power. Evolution of SBS, Rayleigh scattering and forward powers are experimentally investigated with a 25 km segment of single mode fiber. Also, a simple algorithm to predict the generation of SBS is proposed where two criteria of power thresholds was used for comparison with experimental data. (paper)