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Sample records for harmonic converter crystals

  1. Optical and environmentally protective coatings for potassium dihydrogen phosphate (KDP) harmonic converter crystals

    SciTech Connect

    Thomas, I.M.

    1991-06-24

    Potassium dihydrogen phosphate (KDP) crystals have been used as harmonic converters on the Nova laser at LLNL for over six years. All crystals were coated with a single layer, quarterwave AR coating of porous silica with a refractive index of 1.22. This was prepared by a sol-gel process and was applied from a colloidal suspension by spin coating at room temperature. A few crystals were also coated with a methyl silicone coating prior to the application of the AR coating for environmental protection. The initial optical performance of all crystals was very good but there has been some deterioration over the years because of environmental and laser damage degradation. The deterioration in the silicone samples was, however, much less than the others. We are now in the process of replacing all ten KDP arrays with new crystals and will apply the silicone undercoat to all samples. Recently we have been evaluating a new perfluorinated organic polymer coating which has a refractive index of 1.29. This material is soluble in fluorinated solvents and can be applied by dip coating from solution at room temperature. We hope that this can provide environmental protection when applied to KDP and also act as an AR coating at the same time. The optical performance is not as good as our porous silica because of the higher index; about 0.3% reflection per surface is obtained. 4 refs., 10 figs., 1 tab.

  2. Reduced Switching Frequency Active Harmonic Elimination for Multilevel Converters

    SciTech Connect

    Du, Zhong; Tolbert, Leon M; Chiasson, John N; Ozpineci, Burak

    2008-01-01

    This paper presents a reduced switching-frequency active-harmonic-elimination method (RAHEM) to eliminate any number of specific order harmonics of multilevel converters. First, resultant theory is applied to transcendental equations to eliminate low-order harmonics and to determine switching angles for a fundamental frequency-switching scheme. Next, based on the number of harmonics to be eliminated, Newton climbing method is applied to transcendental equations to eliminate high-order harmonics and to determine switching angles for the fundamental frequency-switching scheme. Third, the magnitudes and phases of the residual lower order harmonics are computed, generated, and subtracted from the original voltage waveform to eliminate these low-order harmonics. Compared to the active-harmonic-elimination method (AHEM), which generates square waves to cancel high-order harmonics, RAHEM has lower switching frequency. The simulation results show that the method can effectively eliminate all the specific harmonics, and a low total harmonic distortion (THD) near sine wave is produced. An experimental 11-level H-bridge multilevel converter with a field-programmable gate-array controller is employed to experimentally validate the method. The experimental results show that RAHEM does effectively eliminate any number of specific harmonics, and the output voltage waveform has low switching frequency and low THD.

  3. Generation of harmonics and supercontinuum in nematic liquid crystals

    SciTech Connect

    Nyushkov, B N; Trashkeev, S I; Klementyev, Vasilii M; Pivtsov, V S; Kobtsev, Sergey M

    2013-02-28

    Nonlinear optical properties of nematic liquid crystals (NLC) have been investigated. A technique for efficient laser frequency conversion in a microscopic NLC volume deposited on an optical fibre end face is experimentally demonstrated. An efficient design of a compact NLC-based IR frequency converter with a fibre input and achromatic collimator is proposed and implemented. Simultaneous generation of the second and third harmonics is obtained for the first time under pumping NLC by a 1.56-mm femtosecond fibre laser. The second-harmonic generation efficiency is measured to be about 1 %, while the efficiency of third-harmonic generation is several tenths of percent. A strong polarisation dependence of the third-harmonic generation efficiency is revealed. When pumping NLC by a cw laser, generation of spectral supercontinua (covering the visible and near-IR spectral ranges) is observed. The nonlinear effects revealed can be due to the light-induced change in the orientational order in liquid crystals, which breaks the initial symmetry and leads to formation of disclination structures. The NLC optical nonlinearity is believed to be of mixed orientationalelectronic nature as a whole. (laser optics 2012)

  4. Second harmonic generation from the 'centrosymmetric' crystals.

    PubMed

    Nalla, Venkatram; Medishetty, Raghavender; Wang, Yue; Bai, Zhaozhi; Sun, Handong; Wei, Ji; Vittal, Jagadese J

    2015-05-01

    Second harmonic generation (SHG) is a well known non-linear optical phenomena which can be observed only in non-centrosymmetric crystals due to non-zero hyperpolarizability. In the current work we observed SHG from a Zn(II) complex which was originally thought to have crystallized in the centrosymmetric space group C2/c. This has been attributed to the unequal antiparallel packing of the metal complexes in the non-symmetric space group Cc or residual non-centrosymmetry in C2/c giving rise to polarizability leading to strong SHG. The enhancement of SHG by UV light has been attributed to the increase in non-centrosymmetry and hence polarity of packing due to strain induced in the crystals. The SHG signals measured from these crystals were as large as potassium dihydrogen phosphate crystals, KH2PO4 (KDP), and showed temperature dependence. The highest SHG efficiency was observed at 50 K. The SHG phenomenon was observed at broad wavelengths ranging from visible to below-red in these crystals.

  5. Second harmonic chalcone crystal: Synthesis, growth and characterization

    NASA Astrophysics Data System (ADS)

    D'silva, E. D.; Narayan Rao, D.; Philip, Reji; Butcher, Ray J.; Rajnikant; Dharmaprakash, S. M.

    2011-05-01

    The novel nonlinear optical chalcone derivative (2 E)-3-[4-(methylsulfanyl)phenyl]-1-(3-bromophenyl)prop-2-en-1-one (3Br4MSP) crystals have been grown by slow evaporation technique at ambient temperature. The crystal was subjected to different types of characterization method in order to study its possible application in nonlinear optics. The structure determination of the grown crystal was done by single crystal X-ray diffraction study. The morphology of the crystal is studied. The crystal was subjected to thermal analysis to find its thermal stability. The grown crystals were characterized for their optical transmission and mechanical hardness. The second harmonic generation (SHG) efficiency of the crystal is obtained by classical powdered technique. The laser damage threshold for 3Br4MSP crystal was determined using Q-switched Nd:YAG laser.

  6. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, C.E.; Eimerl, D.; Velsko, S.P.; Roberts, D.

    1993-11-23

    Temperature-insensitive, phase-matched harmonic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions. 12 figures.

  7. Photovoltaic power converter system with a controller configured to actively compensate load harmonics

    DOEpatents

    de Rooij, Michael Andrew; Steigerwald, Robert Louis; Delgado, Eladio Clemente

    2008-12-16

    Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.

  8. Mitigation of harmonic disturbance at pumped storage power station with static frequency converter

    SciTech Connect

    Chiang, J.C.; Wu, C.J.; Yen, S.S.

    1997-09-01

    This paper investigates the harmonic distortion problem and mitigation method at the Mingtan Pumped Storage Power Station in Taiwan, where six 300 MVA synchronous generators/motors are started by a static frequency converter (SFC) before the pumping stage. Since the SFC uses 6-pulse rectifier technique, a large amount of harmonic currents are produced during the starting period. The harmonic distortion level at each bus of the power plant was very high. Especially, the total harmonic distortion (THD) of current at the lighting feeder reached up to 184%, so that power fuses were burned out. At first a 5 mH reactor was inserted in the SFC feeder and a 5th order and high pass filter was installed. However, the harmonic distortion levels were still too high, but there is no space for additional higher-order filters. Finally, the SFC is fed with an individual transformer, and the harmonic disturbance problem is avoided. This paper also gives computer simulations to investigate the harmonic distortion problems and verify the mitigation methods.

  9. Generation of higher odd harmonics in a defective photonic crystal

    SciTech Connect

    Ramanujam, N. R.; Wilson, K. S. Joseph

    2015-06-24

    A photonic crystal (AB){sup 2}(DB)(AB){sup 2} with high refractive index medium as silicon and low refractive medium as air is considered. Using the transfer matrix method, the transmission properties as a function of wavelength with photonic band gaps has been obtained. We are able to demonstrate the generation of third, fifth, seventh and ninth harmonics in the present work. We show that if the air medium is removed in the defect, the defect modes are generated but not harmonics. It can be designed to have a frequency conversion, and have a potential for becoming the basis for the next generation of optical devices.

  10. Second harmonic generation and crystal growth of substituted thienyl chalcone

    NASA Astrophysics Data System (ADS)

    Goto, Yoshitaka; Hayashi, Akio; Kimura, Yasuhiro; Nakayama, Masaharu

    1991-02-01

    The second harmonic generation (SHG) of 29 kinds of thienyl chalcone derivatives with a thiophene ring were examined. A series of 1-{2-(5-bromothienyl)}-3-(4'-halophenyl)propene-3-one showed high SHG activity. Especially 1-(2-thienyl)-3-(4-methylphenyl)propene-1-one had SHG activity 15 times as large as urea and also high blue light region transparency with a cutoff wavelength of 390 nm. A large high quality single crystal of 60x15x10mm of this compound could be obtained from acetone solution. Analysis of the crystal structure identified it as a monoclinical system of space group P2 1.

  11. Second harmonic generation and crystal growth of new chalcone derivatives

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Dharmaprakash, S. M.; Ramakrishna, K.; Fun, Hoong-Kun; Sai Santosh Kumar, R.; Narayana Rao, D.

    2007-05-01

    We report on the synthesis, crystal structure and optical characterization of chalcone derivatives developed for second-order nonlinear optics. The investigation of a series of five chalcone derivatives with the second harmonic generation powder test according to Kurtz and Perry revealed that these chalcones show efficient second-order nonlinear activity. Among them, high-quality single crystals of 3-Br-4'-methoxychalcone (3BMC) were grown by solvent evaporation solution growth technique. Grown crystals were characterized by X-ray powder diffraction (XRD), laser damage threshold, UV-vis-NIR and refractive index measurement studies. Infrared spectroscopy, thermogravimetric analysis and differential thermal analysis measurements were performed to study the molecular vibration and thermal behavior of 3BMC crystal. Thermal analysis does not show any structural phase transition.

  12. Second harmonic generation from the ‘centrosymmetric’ crystals

    PubMed Central

    Nalla, Venkatram; Medishetty, Raghavender; Wang, Yue; Bai, Zhaozhi; Sun, Handong; Wei, Ji.; Vittal, Jagadese J.

    2015-01-01

    Second harmonic generation (SHG) is a well known non-linear optical phenomena which can be observed only in non-centrosymmetric crystals due to non-zero hyperpolarizability. In the current work we observed SHG from a Zn(II) complex which was originally thought to have crystallized in the centrosymmetric space group C2/c. This has been attributed to the unequal antiparallel packing of the metal complexes in the non-symmetric space group Cc or residual non-centrosymmetry in C2/c giving rise to polarizability leading to strong SHG. The enhancement of SHG by UV light has been attributed to the increase in non-centrosymmetry and hence polarity of packing due to strain induced in the crystals. The SHG signals measured from these crystals were as large as potassium dihydrogen phosphate crystals, KH2PO4 (KDP), and showed temperature dependence. The highest SHG efficiency was observed at 50 K. The SHG phenomenon was observed at broad wavelengths ranging from visible to below-red in these crystals. PMID:25995840

  13. Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon

    NASA Astrophysics Data System (ADS)

    Zeng, Y.; Roland, I.; Checoury, X.; Han, Z.; El Kurdi, M.; Sauvage, S.; Gayral, B.; Brimont, C.; Guillet, T.; Mexis, M.; Semond, F.; Boucaud, P.

    2015-02-01

    We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities χzxx (2 ), χzyy (2 ) and the electric fields of the fundamental cavity mode.

  14. Quartz crystal microbalance based on passive frequency to voltage converter

    SciTech Connect

    Burda, Ioan; Tunyagi, Arthur

    2012-02-15

    In dynamics of evaporation or drying of microdrops from a solid surface, a faster and precise quartz crystal microbalance (QCM) is needed. The fast QCM based on frequency to voltage converter is an attractive and powerful tool in the investigation of the dynamic regime of evaporation to translate the frequency shift in terms of a continuous voltage change. The frequency shift monitoring in fast QCM applications is a real challenge for electronic processing interface. Originally developed as a frequency shift processing interface, this novel passive frequency to voltage converter can produce faster, stable, and accurate results in regard to the QCM sensor behavior. In this article, the concept and circuit of passive frequency to voltage converter will be explained followed by static and dynamic characterization. Experimental results of microdrops evaporation will be given.

  15. Resonant second harmonic generation in a gallium nitride two-dimensional photonic crystal on silicon

    SciTech Connect

    Zeng, Y.; Roland, I.; Checoury, X.; Han, Z.; El Kurdi, M.; Sauvage, S.; Boucaud, P.; Gayral, B.; Brimont, C.; Guillet, T.; Mexis, M.; Semond, F.

    2015-02-23

    We demonstrate second harmonic generation in a gallium nitride photonic crystal cavity embedded in a two-dimensional free-standing photonic crystal platform on silicon. The photonic crystal nanocavity is optically pumped with a continuous-wave laser at telecom wavelengths in the transparency window of the nitride material. The harmonic generation is evidenced by the spectral range of the emitted signal, the quadratic power dependence vs. input power, and the spectral dependence of second harmonic signal. The harmonic emission pattern is correlated to the harmonic polarization generated by the second-order nonlinear susceptibilities χ{sub zxx}{sup (2)}, χ{sub zyy}{sup (2)} and the electric fields of the fundamental cavity mode.

  16. Polarization converting textures of nematic liquid crystal in glass cavities

    NASA Astrophysics Data System (ADS)

    Wang, Xiahui; Xu, Miao; Ren, Hongwen

    2014-01-01

    When a nematic liquid crystal (LC) is filled in a glass cavity, the LC molecules present azimuthal orientations in the cavity. If the surface of the cavity is coated with a homeotropic polyimide, then the LC molecules exhibit radial orientations. By treating the LC on one side of the cavity with homogeneous alignment, the former orientations change to a twisted-azimuthal texture, while the latter orientations change to a twisted-radial texture. Both textures are verified experimentally, and they can convert a linearly polarization light to an azimuthal and/or radial polarization light, depending on the polarization direction of the incident light. In contrast to previous approaches, various LC textures can be easily formed in a cavity, and the fabrication procedure is simple. Since the LC texture is confined in a cavity, an array pattern of the texture can be obtained, if the employed substrate has multiple cavities. A LC with twisted-azimuthal and/or twisted-radial textures in a cavity array has potential applications in phase modulation, polarization compensating, sharp focus, and material processing.

  17. Temperature-insensitive phase-matched optical harmonic conversion crystal

    DOEpatents

    Barker, Charles E.; Eimerl, David; Velsko, Stephan P.; Roberts, David

    1993-01-01

    Temperature-insensitive, phase-matched harmomic frequency conversion of laser light at a preferred wavelength of 1.064 microns can be achieved by use of a crystal of deuterated l-arginine phosphate. The crystal is cut and oriented so that the laser light propagates inside the crystal along one of several required directions, which correspond to a temperature-insensitive, phase-matching locus. The method of measuring and calculating the temperature-insensitive, phase-matching angles can be extended to other fundamental wavelengths and other crystal compositions.

  18. Deep-UV 236.5  nm laser by fourth-harmonic generation of a single-crystal fiber Nd:YAG oscillator.

    PubMed

    Deyra, Loïc; Martial, Igor; Didierjean, Julien; Balembois, François; Georges, Patrick

    2014-04-15

    We demonstrate a deep-UV laser at 236.5 nm based on extracavity fourth-harmonic generation of a Q-switched Nd:YAG single-crystal fiber laser at 946 nm. We first compare two nonlinear crystals available for second-harmonic generation: LBO and BiBO. The best results at 473 nm are obtained with a BiBO crystal, with an average output power of 3.4 W at 20 kHz, corresponding to a second-harmonic generation efficiency of 38%. This blue laser is frequency-converted to 236.5 nm in a BBO crystal with an overall fourth-harmonic generation yield of 6.5%, corresponding to an average output power of 600 mW at 20 kHz. This represents an order of magnitude increase in average power and energy compared to previously reported pulsed lasers at 236.5 nm. This work opens the possibility of LIDAR detection of dangerous compounds for military or civilian applications.

  19. Huge enhancement of backward second-harmonic generation with slow light in photonic crystals

    SciTech Connect

    Iliew, Rumen; Etrich, Christoph; Pertsch, Thomas; Kivshar, Yuri S.

    2010-02-15

    We study theoretically forward and backward second-harmonic generation in a two-dimensional photonic crystal structure made of lithium niobate. The aim of this article is twofold: First, we propose a reliable modal algorithm for describing the light propagation taking into account the vectorial character of the interacting fields as well as the tensorial character of the nonlinearity and verify it by means of the nonlinear finite-difference time-domain method. Second, we propose a photonic crystal where we obtain a giant efficiency increase for backward second-harmonic generation with slow light.

  20. Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs

    SciTech Connect

    Buckley, Sonia Radulaski, Marina; Vučković, Jelena; Biermann, Klaus

    2013-11-18

    We demonstrate second harmonic generation at telecommunications wavelengths in photonic crystal cavities in (111)-oriented GaAs. We fabricate 30 photonic crystal structures in both (111)- and (100)-oriented GaAs and observe an increase in generated second harmonic power in the (111) orientation, with the mean power increased by a factor of 3, although there is a large scatter in the measured values. We discuss possible reasons for this increase, in particular, the reduced two photon absorption for transverse electric modes in (111) orientation, as well as a potential increase due to improved mode overlap.

  1. Semiclassical analysis of high harmonic generation in bulk crystals

    NASA Astrophysics Data System (ADS)

    Vampa, G.; McDonald, C. R.; Orlando, G.; Corkum, P. B.; Brabec, T.

    2015-02-01

    High harmonic generation (HHG) in solids is investigated. We find that interband emission is dominant for the midinfrared laser driver frequencies, whereas intraband emission dominates the far-infrared range. Interband HHG is similar to atomic HHG and therewith opens the possibility to apply atomic attosecond technology to the condensed matter phase. Interband emission is investigated with a quasiclassical method, by which HHG can be modeled based on the classical trajectory analysis of electron-hole pairs. This analysis yields a simple approximate cutoff law for HHG in solids. Differences between HHG in atoms and solids are identified that are important for adapting atomic attosecond technology to make it applicable to condensed matter.

  2. Second-harmonic generation of a new chalcone-type crystal

    NASA Astrophysics Data System (ADS)

    Zhang, G. J.; Kinoshita, T.; Sasaki, K.; Goto, Y.; Nakayama, M.

    1990-07-01

    A new type of chalcone crystal was prepared. Anisotropic indices with wavelength dispersion were measured by the Brewster angle method. The two largest second-harmonic generation (SHG) tensor components were determined by the wedge method and compared with d11 of 2-methyl-4-nitroaniline. Calculated collinear and noncollinear phase-matched SHG patterns reasonably fit the observed photographs.

  3. High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter.

    PubMed

    Matko, Vojko; Milanović, Miro

    2016-06-28

    A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal's natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10(-13) frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10(-11) hysteresis frequency difference.

  4. High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter.

    PubMed

    Matko, Vojko; Milanović, Miro

    2016-01-01

    A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal's natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10(-13) frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10(-11) hysteresis frequency difference. PMID:27367688

  5. High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter

    PubMed Central

    Matko, Vojko; Milanović, Miro

    2016-01-01

    A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal’s natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10−13 frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10−11 hysteresis frequency difference. PMID:27367688

  6. Dependence of high-order-harmonic generation on dipole moment in Si O2 crystals

    NASA Astrophysics Data System (ADS)

    Yu, Chao; Zhang, Xirui; Jiang, Shicheng; Cao, Xu; Yuan, Guanglu; Wu, Tong; Bai, Lihua; Lu, Ruifeng

    2016-07-01

    High-order-harmonic generation in α-quartz Si O2 is theoretically investigated under a strong laser field by solving the extended semiconductor Bloch equations. The accurate band structures as well as dipole moments between different bands are obtained from state-of-the-art first-principles calculations. We find that the shapes of k -space-dependent dipole moments play an important role in harmonic generation. The calculated results show that harmonic conversion efficiency is significantly enhanced and the cutoff energy is distinctly increased when the dipole moments change greatly along a valley in the k direction in the solid. Based on that dependence on the dipole moment, we also show that symmetry groups greatly affect the harmonic spectra from the solid materials. Moreover, a two-color synthesized field is used to achieve a supercontinuum harmonic spectrum near the cutoff region, and isolated attosecond pulses can be obtained directly by filtering out the harmonic radiation. We hope the contribution presented in this work provides a useful reference for future studies on laser-crystal interactions.

  7. Ultrashort pulse chirp measurement via transverse second-harmonic generation in strontium barium niobate crystal

    SciTech Connect

    Trull, J.; Wang, B.; Parra, A.; Vilaseca, R.; Cojocaru, C.; Sola, I.; Sheng, Y.

    2015-06-01

    Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.

  8. Towards protein-crystal centering using second-harmonic generation (SHG) microscopy

    SciTech Connect

    Kissick, David J.; Dettmar, Christopher M.; Becker, Michael; Mulichak, Anne M.; Cherezov, Vadim; Ginell, Stephan L.; Battaile, Kevin P.; Keefe, Lisa J.; Fischetti, Robert F.; Simpson, Garth J.

    2013-05-01

    The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-ray diffraction of protein crystals has been explored. The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-ray diffraction of protein crystals was explored. These studies included (i) comparison of microcrystal positions in cryoloops as determined by SHG imaging and by X-ray diffraction rastering and (ii) X-ray structure determinations of selected proteins to investigate the potential for laser-induced damage from SHG imaging. In studies using β{sub 2} adrenergic receptor membrane-protein crystals prepared in lipidic mesophase, the crystal locations identified by SHG images obtained in transmission mode were found to correlate well with the crystal locations identified by raster scanning using an X-ray minibeam. SHG imaging was found to provide about 2 µm spatial resolution and shorter image-acquisition times. The general insensitivity of SHG images to optical scatter enabled the reliable identification of microcrystals within opaque cryocooled lipidic mesophases that were not identified by conventional bright-field imaging. The potential impact of extended exposure of protein crystals to five times a typical imaging dose from an ultrafast laser source was also assessed. Measurements of myoglobin and thaumatin crystals resulted in no statistically significant differences between structures obtained from diffraction data acquired from exposed and unexposed regions of single crystals. Practical constraints for integrating SHG imaging into an active beamline for routine automated crystal centering are discussed.

  9. Intercalating dyes for enhanced contrast in second-harmonic generation imaging of protein crystals.

    PubMed

    Newman, Justin A; Scarborough, Nicole M; Pogranichniy, Nicholas R; Shrestha, Rashmi K; Closser, Richard G; Das, Chittaranjan; Simpson, Garth J

    2015-07-01

    The second-harmonic generation (SHG) activity of protein crystals was found to be enhanced by up to ∼1000-fold by the intercalation of SHG phores within the crystal lattice. Unlike the intercalation of fluorophores, the SHG phores produced no significant background SHG from solvated dye or from dye intercalated into amorphous aggregates. The polarization-dependent SHG is consistent with the chromophores adopting the symmetry of the crystal lattice. In addition, the degree of enhancement for different symmetries of dyes is consistent with theoretical predictions based on the molecular nonlinear optical response. Kinetics studies indicate that intercalation arises over a timeframe of several minutes in lysozyme, with detectable enhancements within seconds. These results provide a potential means to increase the overall diversity of protein crystals and crystal sizes amenable to characterization by SHG microscopy. PMID:26143918

  10. Intercalating dyes for enhanced contrast in second-harmonic generation imaging of protein crystals

    PubMed Central

    Newman, Justin A.; Scarborough, Nicole M.; Pogranichniy, Nicholas R.; Shrestha, Rashmi K.; Closser, Richard G.; Das, Chittaranjan; Simpson, Garth J.

    2015-01-01

    The second-harmonic generation (SHG) activity of protein crystals was found to be enhanced by up to ∼1000-fold by the intercalation of SHG phores within the crystal lattice. Unlike the intercalation of fluorophores, the SHG phores produced no significant background SHG from solvated dye or from dye intercalated into amorphous aggregates. The polarization-dependent SHG is consistent with the chromophores adopting the symmetry of the crystal lattice. In addition, the degree of enhancement for different symmetries of dyes is consistent with theoretical predictions based on the molecular nonlinear optical response. Kinetics studies indicate that intercalation arises over a timeframe of several minutes in lysozyme, with detectable enhancements within seconds. These results provide a potential means to increase the overall diversity of protein crystals and crystal sizes amenable to characterization by SHG microscopy. PMID:26143918

  11. Measuring parameters of large-aperture crystals used for generating optical harmonics

    SciTech Connect

    English, R. E.; Hibbard, R. L.; Michie, R. B.; Wegner, P. J.; Auerbach, J. M.; Norton, M. A.; Summers, M. D.; Perfect, S. A.

    1999-02-23

    The purpose of this project was to develop tools for understanding the influence of crystal quality and crystal mounting on harmonic-generation efficiency at high irradiance. Measuring the homogeneity of crystals interferometrically, making detailed physics calculations of conversion efficiency, performing finite- element modeling of mounted crystals, and designing a new optical metrology tool were key elements in obtaining that understanding. For this work, we used the following frequency-tripling scheme: type I second- harmonic generation followed by type II sum-frequency mixing of the residual fundamental and the second harmonic light. The doubler was potassium dihydrogen phosphate (KDP), and the tripler was deuterated KDP (KD*P). With this scheme, near-infrared light (1053 nm) can be frequency tripled (to 351 nm) at high efficiency (theoretically >90%) for high irradiance (>3 GW/cm²). Spatial variations in the birefringence of the large crystals studied here (37 to 41 cm square by about 1 cm thick) imply that the ideal phase-matching orientation of the crystal with respect to the incident laser beam varies across the crystal. We have shown that phase-measuring interferometry can be used to measure these spatial variations. We observed transmitted wavefront differences between orthogonally polarized interferograms of {lambda}/50 to {lambda}/100, which correspond to index variations of order 10-6. On some plates that we measured, the standard deviation of angular errors is 22-23 µrad; this corresponds to a 1% reduction in efficiency. Because these conversion crystals are relatively thin, their surfaces are not flat (deviate by k2.5 urn from flat). A crystal is mounted against a precision-machined surface that supports the crystal on four edges. This mounting surface is not flat either (deviates by +2.5 µm from flat). A retaining flange presses a compliant element against the crystal. The load thus applied near the edges of the crystal surface holds

  12. Concept for power scaling second harmonic generation using a cascade of nonlinear crystals.

    PubMed

    Hansen, A K; Tawfieq, M; Jensen, O B; Andersen, P E; Sumpf, B; Erbert, G; Petersen, P M

    2015-06-15

    Within the field of high-power second harmonic generation (SHG), power scaling is often hindered by adverse crystal effects such as thermal dephasing arising from the second harmonic (SH) light, which imposes limits on the power that can be generated in many crystals. Here we demonstrate a concept for efficient power scaling of single-pass SHG beyond such limits using a cascade of nonlinear crystals, in which the first crystal is chosen for high nonlinear efficiency and the subsequent crystal(s) are chosen for power handling ability. Using this highly efficient single-pass concept, we generate 3.7 W of continuous-wave diffraction-limited (M(2)=1.25) light at 532 nm from 9.5 W of non-diffraction-limited (M(2)=7.7) light from a tapered laser diode, while avoiding significant thermal effects. Besides constituting the highest SH power yet achieved using a laser diode, this demonstrates that the concept successfully combines the high efficiency of the first stage with the good power handling properties of the subsequent stages. The concept is generally applicable and can be expanded with more stages to obtain even higher efficiency, and extends also to other combinations of nonlinear media suitable for other wavelengths.

  13. Towards protein-crystal centering using second-harmonic generation (SHG) microscopy

    PubMed Central

    Kissick, David J.; Dettmar, Christopher M.; Becker, Michael; Mulichak, Anne M.; Cherezov, Vadim; Ginell, Stephan L.; Battaile, Kevin P.; Keefe, Lisa J.; Fischetti, Robert F.; Simpson, Garth J.

    2013-01-01

    The potential of second-harmonic generation (SHG) microscopy for automated crystal centering to guide synchrotron X-­ray diffraction of protein crystals was explored. These studies included (i) comparison of microcrystal positions in cryoloops as determined by SHG imaging and by X-ray diffraction rastering and (ii) X-ray structure determinations of selected proteins to investigate the potential for laser-induced damage from SHG imaging. In studies using β2 adrenergic receptor membrane-protein crystals prepared in lipidic mesophase, the crystal locations identified by SHG images obtained in transmission mode were found to correlate well with the crystal locations identified by raster scanning using an X-­ray minibeam. SHG imaging was found to provide about 2 µm spatial resolution and shorter image-acquisition times. The general insensitivity of SHG images to optical scatter enabled the reliable identification of microcrystals within opaque cryocooled lipidic mesophases that were not identified by conventional bright-field imaging. The potential impact of extended exposure of protein crystals to five times a typical imaging dose from an ultrafast laser source was also assessed. Measurements of myoglobin and thaumatin crystals resulted in no statistically significant differences between structures obtained from diffraction data acquired from exposed and unexposed regions of single crystals. Practical constraints for integrating SHG imaging into an active beamline for routine automated crystal centering are discussed. PMID:23633594

  14. Optical second-harmonic generation enhanced by a twist defect in ferroelectric liquid crystals.

    PubMed

    Hoshi, Hajime; Ishikawa, Ken; Takezoe, Hideo

    2003-08-01

    Second-harmonic generation (SHG) spectra were numerically calculated in ferroelectric liquid crystals with a twist defect. It is shown that SHG is enhanced when the SHG wavelength is close to the defect mode. The spectral width of the enhanced peak becomes sharper with increasing the sample thickness at the same rate for the width of the defect mode peak. The SHG peak intensity increases with about seventh power of the sample thickness.

  15. How a silver dendritic mesocrystal converts to a single crystal

    SciTech Connect

    Fang, J.; Ding, B.; Song, X.; Han, Y.

    2008-05-02

    In this paper, we demonstrate how a silver dendrite transforms from mesocrystal into single crystal and the stability for a dendritic silver mesocrystal within a Sn/AgNO3 galvanic replacement reaction. Our findings provide the direct evidence and visible picture of the transformation from mesocrystal to single crystalline structure and further confirm the particle-mediated crystallization mechanism. At the initial stage of the transformation, there is a crystallographic fusion process, dominated by oriented attachment mechanism. Ostwald ripening also plays an important role in forming smooth surface and regular shape of the final nanocrystal.

  16. Study of the second harmonic generation and optical rectification in a cBN crystal

    SciTech Connect

    Dou Qingping; Ma Haitao; Jia Gang; Chen Zhanguo; Cao Kun; Zhang Tiechen

    2007-02-28

    Cubic boron nitride (cBN) - a kind of an artificial (synthetic) crystal with the band gap of {approx}6.3 eV, which has the zinc blende structure and the 4-bar 3m symmetry, is studied. The optical rectification is obtained and the second harmonic generation (SHG) is observed in the cBN crystal for the first time by using a 1064-nm Q-switched Nd:YAG laser. The green light at 532 nm from the cBN sample can be seen with a naked eye. (nonlinear optical phenomena)

  17. Highly efficient mode converter for coupling light into wide slot photonic crystal waveguide.

    PubMed

    Zhang, Xingyu; Subbaraman, Harish; Hosseini, Amir; Chen, Ray T

    2014-08-25

    We design, fabricate and experimentally demonstrate a highly efficient adiabatic mode converter for coupling light into a silicon slot waveguide with a slot width as large as 320 nm. This strip-to-slot mode converter is optimized to provide a measured insertion loss as low as 0.08 dB. Our mode converter provides 0.1 dB lower loss compared to a conventional V-shape mode converter. This mode converter is used to couple light into and out of a 320 nm slot photonic crystal waveguide, and it is experimentally shown to improve the coupling efficiency up to 3.5 dB compared to the V-shape mode converter, over the slow-light wavelength region.

  18. Efficient intracavity second-harmonic generation at 1063 nm in a GdCOB crystal

    NASA Astrophysics Data System (ADS)

    Wu, Z. C.; Liu, W. M.

    2011-12-01

    We report an efficient intracavity second-harmonic generation (SHG) at 1063 nm in a non-linear optical crystal, GdCa4O(BO3)3 (GdCOB), performed with a diode end pumped continuous-wave (CW) Nd:GdVO4 laser. In the case of a laser with an a-cut 0.4 at % Nd:GdVO4 crystal frequency-doubled with a GdCOB crystal cut for Type I frequency doubling. A CW SHG output power of 2.25 W has been obtained using a 15 mm long GCOB crystal. The optical conversion efficiency with respect to the incident pump power was 12.4%.

  19. Real-time observation of interfering crystal electrons in high-harmonic generation.

    PubMed

    Hohenleutner, M; Langer, F; Schubert, O; Knorr, M; Huttner, U; Koch, S W; Kira, M; Huber, R

    2015-07-30

    Acceleration and collision of particles has been a key strategy for exploring the texture of matter. Strong light waves can control and recollide electronic wavepackets, generating high-harmonic radiation that encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of high-harmonic generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems, and provides hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not so far been observable in real time. Here we study high-harmonic generation in a bulk solid directly in the time domain, and reveal a new kind of strong-field excitation in the crystal. Unlike established atomic sources, our solid emits high-harmonic radiation as a sequence of subcycle bursts that coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features are characteristic of a non-perturbative quantum interference process that involves electrons from multiple valence bands. These results identify key mechanisms for future solid-state attosecond sources and next-generation light-wave electronics. The new quantum interference process justifies the hope for all-optical band-structure reconstruction and lays the foundation for possible quantum logic operations at optical clock rates.

  20. Real-time observation of interfering crystal electrons in high-harmonic generation.

    PubMed

    Hohenleutner, M; Langer, F; Schubert, O; Knorr, M; Huttner, U; Koch, S W; Kira, M; Huber, R

    2015-07-30

    Acceleration and collision of particles has been a key strategy for exploring the texture of matter. Strong light waves can control and recollide electronic wavepackets, generating high-harmonic radiation that encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of high-harmonic generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems, and provides hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not so far been observable in real time. Here we study high-harmonic generation in a bulk solid directly in the time domain, and reveal a new kind of strong-field excitation in the crystal. Unlike established atomic sources, our solid emits high-harmonic radiation as a sequence of subcycle bursts that coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features are characteristic of a non-perturbative quantum interference process that involves electrons from multiple valence bands. These results identify key mechanisms for future solid-state attosecond sources and next-generation light-wave electronics. The new quantum interference process justifies the hope for all-optical band-structure reconstruction and lays the foundation for possible quantum logic operations at optical clock rates. PMID:26223624

  1. An azo-bridged ferroelectric liquid crystal with highly enhanced second and third harmonic generation.

    PubMed

    Zhang, Yongqiang; Ortega, Josu; Baumeister, Ute; Folcia, César L; Sanz-Enguita, Gerardo; Walker, Christopher; Rodriguez-Conde, Sofía; Etxebarria, Jesus; O'Callaghan, Michael J; More, Kundalika

    2012-10-01

    A laterally azo-bridged trimer ferroelectric liquid crystal (FLC) incorporating a strong chromophore along its polar axis was synthesized and characterized by polarized-light optical microscopy, differential scanning calorimetry, two-dimensional X-ray diffraction analysis, electro-optical measurements, and nonlinear optical (NLO) investigations. This mesogen exhibits a thermodynamically stable enantiotropic SmC* phase and a bistable ferroelectric switching in a surface stabilized cell with bookshelf geometry. It gives the resonance-enhanced d(22) coefficient of 28 pm V(-1) (λ = 1.369 μm) for second harmonic generation (SHG), the largest NLO susceptibility reported to date for all FLCs. At the same wavelength, a new type of helicoidal phase matching assisted by the helical SmC* structure was identified. When the second harmonic wavelength of 780 nm is far away from the resonance wavelength (λ(max) = 572 nm), the d(22) coefficient is reduced to 6.8 pm V(-1) (λ = 1.56 μm). In addition to a strong SHG activity, the trimer also shows a strong third harmonic generation (THG) with an estimated third-order nonlinear susceptibility of χ((3)) = ~3 × 10(-11) esu (λ = 1.56 μm), among the largest χ((3)) value reported from THG measurements for liquid crystals. This work enables viable applications of FLCs in nonlinear optics and offers an innovative approach to develop new FLCs with larger NLO strength. PMID:22909407

  2. Third-harmonic generation enhancement in polymer-dispersed liquid crystal grating

    NASA Astrophysics Data System (ADS)

    Wicharn, S.; Buranasiri, P.

    2014-09-01

    In this paper, the enhancement of third-harmonic generation in one-dimensional periodic grating structure with lowindex contrast, which is produced by holographic illuminated liquid crystal droplets and called polymer-dispersed liquid crystal grating, with near-infrared pumping has been demonstrated. The observed enhancement process is theoretically explained and modeled with a multi-scale perturbation analysis and split-step Fourier transform technique, respectively. We show that the third-harmonic generation has been enhanced by setting the fundamental frequency wavelength to the long-wavelength band-edge of the first photonic band-gap of this periodic structure and satisfying band-edge phasematched condition. The numerical results show that a dramatic enhancement of the third-harmonic field is observed near the long-wavelength band-edge of the second photonic band-gap. Furthermore, the conversion efficiency of thirdharmonic field of forward-propagating direction is more than of backward-propagating direction by a factor of 600.

  3. Structural light focusing phenomenon and enhanced second harmonic generation in NaNO2-infiltrated opal photonic crystal

    NASA Astrophysics Data System (ADS)

    Zaytsev, Kirill I.; Katyba, Gleb M.; Yakovlev, Egor V.; Aliev, Ismail N.; Khorokhorov, Alexey M.; Yurchenko, Stanislav O.

    2015-01-01

    We report new experimental results on enhanced second harmonic generation using a structural light focusing phenomenon in photonic crystals (PCs). We use opal-based PC, infiltrated with NaNO2 and pumped with femtosecond laser pulses at various incidence angles, in order to examine the dependence of second harmonic generation efficiency on the pumping wavelength location toward the PC band-gap. We demonstrate one order enhancement of second harmonic generation in case of PC band-gap pumping in comparison to non-band- gap pumping. Second harmonic generation is performed in reflection mode with the maximum of generation in the direction of mirror reflection. We demonstrate that the spectrum of second harmonic does not narrow with the quasi-phase matching condition in case of band-gap generation, and second harmonic spectrum corresponding to non-band-gap generation undergoes 1.5 times narrowing due to the quasi-phase matching.

  4. Nuclear motion effects on the density matrix of crystals: an ab initio Monte Carlo harmonic approach.

    PubMed

    Pisani, Cesare; Erba, Alessandro; Ferrabone, Matteo; Dovesi, Roberto

    2012-07-28

    In the frame of the Born-Oppenheimer approximation, nuclear motions in crystals can be simulated rather accurately using a harmonic model. In turn, the electronic first-order density matrix (DM) can be expressed as the statistically weighted average over all its determinations each resulting from an instantaneous nuclear configuration. This model has been implemented in a computational scheme which adopts an ab initio one-electron (Hartree-Fock or Kohn-Sham) Hamiltonian in the CRYSTAL program. After selecting a supercell of reasonable size and solving the corresponding vibrational problem in the harmonic approximation, a Metropolis algorithm is adopted for generating a sample of nuclear configurations which reflects their probability distribution at a given temperature. For each configuration in the sample the "instantaneous" DM is calculated, and its contribution to the observables of interest is extracted. Translational and point symmetry of the crystal as reflected in its average DM are fully exploited. The influence of zero-point and thermal motion of nuclei on such important first-order observables as x-ray structure factors and Compton profiles can thus be estimated.

  5. Broadband second harmonic generation in an imperfect nonlinear photonic crystal with random defects

    NASA Astrophysics Data System (ADS)

    Ren, Kun; Liu, Yali; Ren, Xiaobin; Fan, Jingyang

    2016-09-01

    In this paper, we study broadband second harmonic generation (SHG) in an imperfect nonlinear photonic crystal in which defects are introduced with random lengths. We show that the efficient SHG output is obtained when the length of each defect varies near certain specialized values. The bandwidth of the SHG output broadens with the increasing randomness of defect length. Moreover, the SHG bandwidth is nearly unaffected only when the total length of the whole structure is long enough. The disordered structure also exhibits good tolerance to the fabrication error, which provides a way to control SHG intensity and bandwidth separately.

  6. Polar structure of disclination loops in nematic liquid crystals probed by second-harmonic-light scattering.

    PubMed

    Pardaev, Shokir A; Williams, J C; Twieg, R J; Jakli, A; Gleeson, J T; Ellman, B; Sprunt, S

    2015-03-01

    Angle-resolved, second-harmonic-light scattering (SHLS) measurements are reported for three different classes of thermotropic nematic liquid crystals (NLCs): polar and nonpolar rodlike compounds and a bent-core compound. Results revealing well-defined scattering peaks are interpreted in terms of the electric polarization induced by distortions of the nematic orientational field ("flexopolarity") associated with inversion wall defects, nonsingular disclinations, analogous to Neel walls in ferromagnets, that often exhibit a closed loop morphology in NLCs. Analysis of the SHLS patterns based on this model provides a "proof-of-concept" for a potentially useful method to probe the flexopolar properties of NLCs.

  7. Calculation of optical second-harmonic susceptibilities and optical activity for crystals

    SciTech Connect

    Levine, Z.H.

    1994-12-31

    A new generation of nearly first-principles calculations predicts both the linear and second-harmonic susceptibilities for a variety of insulating crystals, including GaAs, GaP, AlAs, AlP, Se, {alpha}-quartz, and c-urea. The results are typically in agreement with experimental measurements. The calculations have been extended to optical activity, with somewhat less success to date. The theory, based on a simple self-energy correction to the local density approximation, and results are reviewed herein.

  8. Ab initio description of second-harmonic generation from crystal surfaces

    NASA Astrophysics Data System (ADS)

    Tancogne-Dejean, Nicolas; Giorgetti, Christine; Véniard, Valérie

    2016-09-01

    We propose an ab initio framework to derive the dielectric and the second-order susceptibility tensors for crystal surfaces. The single-surface response is extracted from a supercell scheme. We evaluate macroscopic quantities, taking into account the local fields. The first- and second-order susceptibilities are evaluated within time-dependent density functional theory, in the long-wavelength limit. We apply our formalism to the calculation of the second-harmonic generation for clean and hydrogenated silicon surfaces. The agreement with measured second-order susceptibility components is significantly better, illustrating the importance of local-field effects.

  9. Multiple copies of orbital angular momentum states through second-harmonic generation in a two-dimensional periodically poled LiTaO{sub 3} crystal

    SciTech Connect

    Fang, Xinyuan; Wei, Dunzhao; Liu, Dongmei; Zhong, Weihao; Ni, Rui; Chen, Zhenhua; Hu, Xiaopeng; Zhang, Yong Zhu, S. N.; Xiao, Min

    2015-10-19

    We experimentally demonstrate multiple copies of optical orbital angular momentum (OAM) states through quasi-phase-matched (QPM) second-harmonic (SH) generation in a 2D periodically poled LiTaO{sub 3} (PPLT) crystal. Since the QPM condition is satisfied by involving different reciprocal vectors in the 2D PPLT crystal, collinear and noncollinear SH beams carrying OAMs of l{sub 2} are simultaneously generated by the input fundamental beam with an OAM of l{sub 1}. The OAM conservation law (i.e., l{sub 2} = 2l{sub 1}) holds well in the experiment, which can tolerate certain phase-mismatch between the interacting waves. Our results provide an efficient way to obtain multiple copies of the wavelength-converted OAM states, which can be used to enhance the capacity in optical communications.

  10. Multi-direction high-efficiency second harmonic generation in ellipse structure nonlinear photonic crystals

    SciTech Connect

    Chen, Bao-Qin; Zhang, Chao; Liu, Rong-Juan; Li, Zhi-Yuan

    2014-10-13

    We have designed and fabricated a lithium niobate (LN) nonlinear photonic crystal (NPC) with a two-dimensional (2D) ellipse structure of inverse poling domains. The structure can offer continuously varying reciprocal lattice vectors in different directions to compensate the phase-mismatching during the second harmonic generation (SHG) for diverse pump wavelengths. We consider three propagation directions with large effective nonlinear susceptibility and measure the nonlinear conversion efficiency of SHG. The experimental data are in good agreement with the quantitative calculation results using the effective susceptibility model with pump depletion. With high-efficiency SHG in multiple propagation direction, the 2D ellipse structure of LN NPC has the potential to realize various broadband nonlinear frequency conversion processes in different propagation direction with a single crystal.

  11. Investigation of a metallic photonic crystal high power microwave mode converter

    SciTech Connect

    Wang, Dong Qin, Fen; Xu, Sha; Yu, Aimin; Wu, Yong

    2015-02-15

    It is demonstrated that an L band metallic photonic crystal TEM-TE{sub 11} mode converter is suitable for narrow band high power microwave application. The proposed mode converter is realized by partially filling metallic photonic crystals along azimuthal direction in a coaxial transmission line for phase-shifting. A three rows structure is designed and simulated by commercial software CST Microwave Studio. Simulation results show that its conversion efficiency is 99% at the center frequency 1.58 GHz. Over the frequency range of 1.56-1.625 GHz, the conversion efficiency exceeds 90 %, with a corresponding bandwidth of 4.1 %. This mode converter has a gigawatt level power handling capability which is suitable for narrow band high power microwave application. Using magnetically insulated transmission line oscillator(MILO) as a high power microwave source, particle-in-cell simulation is carried out to test the performance of the mode converter. The expected TE{sub 11} mode microwave output is obtained and the MILO works well. Mode conversion performance of the converter is tested by far-field measurement method. And the experimental result confirms the validity of our design. Then, high power microwave experiment is carried out on a Marx-driven Blumlein water line pulsed power accelerator. Microwave frequency, radiated pattern and power are measured in the far-field region and the results agree well with simulation results. The experiment also reveals that no microwave breakdown or pulse shortening took place in the experimental setup.

  12. Large enhancement of third-harmonic generation induced by coupled gap solitons in chi(3) nonlinear photonic crystals.

    PubMed

    Xie, Ping; Zhang, Zhao-Qing

    2005-02-01

    It is shown that, in a chi((3)) nonlinear photonic crystal, the third-harmonic conversion efficiency can be enhanced by about three orders of magnitude via the formation of self-organized localized states inside the gaps as compared with that in a bulk medium of the same length with a perfect phase-matching condition. These localized states contain both the fundamental and third-harmonic frequencies located in different gaps. Their existence is a result of both the Kerr effect and the large energy transfer between fundamental and third-harmonic waves.

  13. Crystal growth and second harmonic generation efficiency of a chalcone derivative

    NASA Astrophysics Data System (ADS)

    Meenatchi, V.; Muthu, K.; Rajasekar, M.; Meenakshisundaram, SP.

    2013-06-01

    Single crystals of (2E,6E)-2-(4-fluorobenzylidine)-6-(4-methoxybenzylidine)cyclohexanone (FBMBC) have been grown by a slow evaporation solution growth technique from ethanol at room temperature. The single crystal X-ray diffraction study reveals that the FBMBC belongs to triclinic system and the cell parameters are a=9.790(6) Å, b=12.08(7) Å, c=14.09(9) Å and V=1577 Å3. The structure and the crystallinity of the material were further confirmed by powder X-ray diffraction analysis. The various functional groups present in the molecule are confirmed by Fourier transform infrared spectral analysis. The scanning electron microscopy study reveals the surface morphology of the as-grown crystal. Thermogravimetric/differential thermal analysis studies reveal the purity of the material and the crystals are transparent in the visible region having a low optical cut-off at ∼475 nm. The second harmonic generation efficiency of FBMBC is estimated by the Kurtz and Perry technique. Theoretical calculations were performed using the Hartree-Fock method with 6-31 G(d,p) as the basis set to derive the optimized geometry and the first-order molecular hyperpolarizability (β) values.

  14. Type-II second-harmonic-generation properties of YCOB and GdCOB single crystals.

    PubMed

    Liu, Yanqing; Qi, Hongwei; Lu, Qingming; Yu, Fapeng; Wang, Zhengping; Xu, Xinguang; Zhao, Xian

    2015-02-01

    As excellent nonlinear optical (NLO) crystals, YCa(4)O(BO(3))(3) (YCOB) and GdCa(4)O(BO(3))(3) (GdCOB) have been paid much attention since their first appearance in 1990's. From that time to now, almost all of related researches and applications have focused on their type-I phase-matching (PM) configurations which possess large effective NLO coefficient (d(eff)). In this paper, type-II second-harmonic-generation (SHG) properties of these two crystals are reported, including PM curve, d(eff), angular acceptance and walk-off angle. Both of the type-II SHG experiments for 1064 and 1320 nm have indicated that the optimum directions which have maximum d(eff) locate in the second octant, i.e. (90° < θ< 180°, 0° < ϕ < 90°). For a (112°, 81.3°)-cut, 24 mm long YCOB crystal, the largest type-II SHG conversion efficiency of a 1064 nm Nd:YAG pico-second laser is 55%, which reaches the same level of the optimum type-I sample. To our knowledge this is the first time that type-II SHG performance of YCOB and GdCOB crystals is investigated intensively. Our research has shown that the smaller d(eff) of type-II PM can be compensated by its larger angular acceptance and less beam walk-off. The same level SHG conversion efficiency implies for such type crystals the type-II components have the potential to replace type-I ones and obtain important NLO applications in the future.

  15. Type-II second-harmonic-generation properties of YCOB and GdCOB single crystals.

    PubMed

    Liu, Yanqing; Qi, Hongwei; Lu, Qingming; Yu, Fapeng; Wang, Zhengping; Xu, Xinguang; Zhao, Xian

    2015-02-01

    As excellent nonlinear optical (NLO) crystals, YCa(4)O(BO(3))(3) (YCOB) and GdCa(4)O(BO(3))(3) (GdCOB) have been paid much attention since their first appearance in 1990's. From that time to now, almost all of related researches and applications have focused on their type-I phase-matching (PM) configurations which possess large effective NLO coefficient (d(eff)). In this paper, type-II second-harmonic-generation (SHG) properties of these two crystals are reported, including PM curve, d(eff), angular acceptance and walk-off angle. Both of the type-II SHG experiments for 1064 and 1320 nm have indicated that the optimum directions which have maximum d(eff) locate in the second octant, i.e. (90° < θ< 180°, 0° < ϕ < 90°). For a (112°, 81.3°)-cut, 24 mm long YCOB crystal, the largest type-II SHG conversion efficiency of a 1064 nm Nd:YAG pico-second laser is 55%, which reaches the same level of the optimum type-I sample. To our knowledge this is the first time that type-II SHG performance of YCOB and GdCOB crystals is investigated intensively. Our research has shown that the smaller d(eff) of type-II PM can be compensated by its larger angular acceptance and less beam walk-off. The same level SHG conversion efficiency implies for such type crystals the type-II components have the potential to replace type-I ones and obtain important NLO applications in the future. PMID:25836087

  16. The second-harmonic response of single-crystal silver electrodes obtained with an interference method

    NASA Astrophysics Data System (ADS)

    Beltramo, G.; Bilger, C.; Pettinger, B.; Schmickler, W.

    1998-12-01

    The second-harmonic response of several single-crystal silver electrodes is investigated at a long wavelength. In contrast to earlier experiments, the phase of the signal is obtained directly by an interference method. By comparing measurements at two different angles of incidence, the Rudnick-Stern coefficient characterizing the response perpendicular to the surface can be estimated; for Ag(100) and Ag(111) it agrees fairly well with calculations based on the jellium model. For the Ag(110) surface, the twofold amplitude depends on the electrode potential; in addition, a contribution with a three-fold symmetry is observed. These unexpected features are probably caused by a facetting of the Ag(110) surface.

  17. Enhanced third harmonic generation by organic materials on high-Q plasmonic photonic crystals.

    PubMed

    Ren, Fanghui; Wang, Xiangyu; Li, Zhong'an; Luo, Jingdong; Jang, Sei-Hum; Jen, Alex K-Y; Wang, Alan X

    2014-08-25

    The enhanced optical nonlinearity enabled by localized plasmonic fields has been well studied for all-optical switching processing (AOSP) devices for future optical communication systems. In this work, plasmonic photonic crystals with a nonlinear polycarbonate/polymethine blend cladding layer are designed to enhance the third harmonic generation (THG) at the telecom wavelengths (~1550 nm). Due to the presence of he two-dimensional (2-D) gold nano-patch arrays with improved Q-factor and high local fields, more than 20 × of enhanced THG signals in the hybrid organic-plasmonic nanostructure are experimentally observed. The enhanced THG in the hybrid organic-plasmonic materials suggested that such extraordinary nonlinear effects can be used for AOSP devices and wavelength conversion.

  18. Layer- and frequency-dependent second harmonic generation in reflection from GaSe atomic crystals

    NASA Astrophysics Data System (ADS)

    Tang, Yanhao; Mandal, Krishna C.; McGuire, John A.; Lai, Chih Wei

    2016-09-01

    We report optical second-harmonic generation (SHG) in reflection from GaSe crystals of 1 to more than 100 layers using a fundamental picosecond pulsed pump at 1.58 eV and a supercontinuum white light pulsed laser with energies ranging from 0.85 to 1.4 eV. The measured reflected SHG signal is maximal in samples of ˜20 layers, decreasing in thicker samples as a result of interference. The thickness- and frequency-dependence of the SHG response of samples thicker than ˜7 layers can be reproduced by a second-order optical susceptibility that is the same as in bulk samples. For samples ≲7 layers, the second-order optical susceptibility is reduced compared to that in thicker samples, which is attributed to the expected band-gap increase in mono- and few-layer GaSe.

  19. Surface plasmon-driven second-harmonic generation asymmetry in anisotropic plasmonic crystals

    NASA Astrophysics Data System (ADS)

    Chekhov, A. L.; Razdolski, I.; Kirilyuk, A.; Rasing, Th.; Stognij, A. I.; Murzina, T. V.

    2016-04-01

    We report a strong angular asymmetry of optical second-harmonic generation (SHG) in plasmonic crystals formed by an Au grating on top of an anisotropic bismuth-thulium iron garnet (BTIG) film. We found that a weak anisotropy-driven angular SHG asymmetry of the crystalline BTIG is resonantly enhanced and reaches 95% as the surface plasmon polariton (SPP) is excited at the Au/BTIG interface. The asymmetry introduced by an interference of the odd and even (with respect to the angle of incidence) SHG fields is attributed to the anisotropy of the BTIG film. The angular SHG spectra are reproduced using a simple model with a resonant SPP-induced SHG contribution from the anisotropic Au/BTIG interface. The observed asymmetry of the SHG provides valuable insight into the mechanisms of nonlinear plasmonics and can noticeably expand its abilities regarding active light conversion and manipulation.

  20. Photoinduced second harmonic generation in partially crystallized BiB 3O 6 glass

    NASA Astrophysics Data System (ADS)

    Kityk, I. V.; Imiołek, W.; Majchrowski, A.; Michalski, E.

    2003-04-01

    Photoinduced second harmonic generation was found in BiB 3O 6 (BiBO) glass having different degree of crystallinity. We have revealed that an increasing degree of crystallinity of BiBO glass leads to increase of the output second-order optical susceptibility. We have used a pulsed 35 MW nitrogen laser ( λ=337 nm; τ=50 ps) as a source of photoinducing laser beam. Fundamental laser beam was generated by pulsed Nd:YAG laser ( λ=1.06 μm; time duration about 25 ps). Maximal value of the photoinduced second-order non-linear optical susceptibility d222 was equal to about 5 pm/V, what is substantially higher than in case of BiBO single crystals (˜ 3 pm/ V).

  1. Temperature-frequency converter using a liquid crystal cell as a sensing element.

    PubMed

    Marcos, Carlos; Sánchez Pena, José M; Torres, Juan C; Isidro Santos, José

    2012-01-01

    A new temperature-frequency converter based on the variation of the dielectric permittivity of the Liquid Crystal (LC) material with temperature has been demonstrated. Unlike other temperature sensors based on liquid crystal processing optical signals for determining the temperature, this work presents a system that is able to sense temperature by using only electrical signals. The variation of the dielectric permittivity with temperature is used to modify the capacitance of a plain capacitor using a LC material as non-ideal dielectric. An electric oscillator with an output frequency depending on variable capacitance made of a twisted-nematic (TN) liquid crystal (LC) cell has been built. The output frequency is related to the temperature of LC cell through the equations associated to the oscillator circuit. The experimental results show excellent temperature sensitivity, with a variation of 0.40% of the initial frequency per degree Celsius in the temperature range from -6 °C to 110 °C.

  2. High energy, high repetition rate, second harmonic generation in large aperture DKDP, YCOB, and LBO crystals.

    PubMed

    Phillips, Jonathan P; Banerjee, Saumyabrata; Smith, Jodie; Fitton, Mike; Davenne, Tristan; Ertel, Klaus; Mason, Paul; Butcher, Thomas; De Vido, Mariastefania; Greenhalgh, Justin; Edwards, Chris; Hernandez-Gomez, Cristina; Collier, John

    2016-08-22

    We report on type-I phase-matched second harmonic generation (SHG) in three nonlinear crystals: DKDP (98% deuteration), YCOB (XZ plane), and LBO (XY plane), of 8 J, 10 Hz cryogenic gas cooled Yb:YAG laser operating at 1029.5 nm. DKDP exhibited an efficiency of 45% at a peak fundamental intensity of 0.24 GW/cm2 for 10 Hz operation at 10 ns. At the same intensity and repetition rate, YCOB and LBO showed 50% and 65% conversion efficiencies, respectively. Significant improvement in conversion efficiency, to a maximum of 82%, was demonstrated in LBO at 0.7 GW/cm2 and 10 Hz, generating output energy of 5.6 J at 514.75 nm, without damage or degradation. However, no improvement in conversion efficiency was recorded for YCOB at this increased intensity. Additionally, we present theoretically calculated temperature maps for both 10 J and 100 J operation at 10 Hz, and discuss the suitability of these three crystals for frequency conversion of a 100 J, 10 Hz diode pumped solid state laser (DPSSL). PMID:27557246

  3. High energy, high repetition rate, second harmonic generation in large aperture DKDP, YCOB, and LBO crystals.

    PubMed

    Phillips, Jonathan P; Banerjee, Saumyabrata; Smith, Jodie; Fitton, Mike; Davenne, Tristan; Ertel, Klaus; Mason, Paul; Butcher, Thomas; De Vido, Mariastefania; Greenhalgh, Justin; Edwards, Chris; Hernandez-Gomez, Cristina; Collier, John

    2016-08-22

    We report on type-I phase-matched second harmonic generation (SHG) in three nonlinear crystals: DKDP (98% deuteration), YCOB (XZ plane), and LBO (XY plane), of 8 J, 10 Hz cryogenic gas cooled Yb:YAG laser operating at 1029.5 nm. DKDP exhibited an efficiency of 45% at a peak fundamental intensity of 0.24 GW/cm2 for 10 Hz operation at 10 ns. At the same intensity and repetition rate, YCOB and LBO showed 50% and 65% conversion efficiencies, respectively. Significant improvement in conversion efficiency, to a maximum of 82%, was demonstrated in LBO at 0.7 GW/cm2 and 10 Hz, generating output energy of 5.6 J at 514.75 nm, without damage or degradation. However, no improvement in conversion efficiency was recorded for YCOB at this increased intensity. Additionally, we present theoretically calculated temperature maps for both 10 J and 100 J operation at 10 Hz, and discuss the suitability of these three crystals for frequency conversion of a 100 J, 10 Hz diode pumped solid state laser (DPSSL).

  4. Acoustic harmonic generation from fatigue-generated dislocation substructures in copper single crystals

    NASA Astrophysics Data System (ADS)

    Apple, T. M.; Cantrell, J. H.; Amaro, C. M.; Mayer, C. R.; Yost, W. T.; Agnew, S. R.; Howe, J. M.

    2013-07-01

    Dislocations generated during cyclic loading of metals self-organize into substructures that produce substantial changes in the nonlinear response. The nonlinearity is quantified by the material nonlinearity parameter ? extracted from acoustic harmonic generation measurements. Measurements of ? on copper single crystals oriented for single-slip ([1 2 3] loading axis) and fatigued in plastic strain control are compared to calculations of ? obtained from the Cantrell model for which measured values of model parameters associated with the substructures are required. Transmission electron microscopy measurements of the volume fractions of veins and persistent slip bands, dislocation loop lengths, dipole heights and the densities of primary and secondary dislocations in the fatigue-generated substructures are obtained for input into the model calculations. The model predictions agree with the values observed experimentally. In particular, the experimental data show an increase in ? proportional to ? where ? is the cumulative plastic strain and m is 0.7 and 0.4, respectively, for acoustic wave propagation along the ? and ? crystal axes. Such dependence is consistent with the Cantrell model and at variance with models, based on assumed variations in the third-order elastic constants, which predict an exponential dependence on ? .

  5. Photonic crystal surface-emitting lasers as a pumping light source for second harmonic generation

    NASA Astrophysics Data System (ADS)

    Watanabe, Akiyoshi; Hirose, Kazuyoshi; Kurosaka, Yoshitaka; Sugiyama, Takahiro; Liang, Yong; Noda, Susumu

    2014-02-01

    Photonic crystal surface emitting lasers (PCSELs) have recently been achieved with both a single spectrum and narrow spot beam pattern under several hundred mW of output power. Even though the high coherence properties of PCSELs are expected to be used for various applications, we have focused on a pumping light source for a wavelength conversion system in this work. We fabricated a 1.06 μm PCSEL with a square lattice 2D photonic crystal in which the lattice period corresponded to the lasing wavelength to obtain green light. The fabricated device had a narrow spot beam pattern of less than 0.5 degrees and a single spectrum at 1068 nm under CW output power of more than 200 mW despite the broad emitting area of 200 × 200 μm2. The wavelength conversion system used single pass second-harmonic generation (SHG) that consisted of only the PCSEL and 50 mm long bulk MgO doped periodically with poled lithium niobate (MgO:PPLN) as a nonlinear medium, i.e., it was a lens-free system. It was important to maintain the high brightness of the pumping light in this system with a single spectrum through the MgO:PPLN. As a result, SHG light was obtained at 534 nm with a narrow spot beam pattern, which followed the beam quality of the PCSEL under CW operation.

  6. A harmonic transition state theory model for defect initiation in crystals

    NASA Astrophysics Data System (ADS)

    Delph, T. J.; Cao, P.; Park, H. S.; Zimmerman, J. A.

    2013-03-01

    We outline here a model for the initiation of defects in crystals based upon harmonic transition state theory (hTST). This model combines a previously developed model for zero-temperature defect initiation with a multi-dimensional hTST model that is capable of accurately predicting the effects of temperature and loading rate upon defect initiation. The model has several features that set it apart from previous efforts along these lines, most notably a straightforward method of determining the energy barrier between adjacent equilibrium states that does not depend upon a priori information concerning the nature of the defect. We apply the model to two examples, triaxial stretching of a perfect fcc crystal and nanoindentation of a gold substrate. Very good agreement is found between the predictions of the model and independent molecular dynamics (MD) simulations. Among other things, the model predicts a strong dependence of the defect initiation behavior upon the loading parameter. A very attractive feature of this model is that it is valid for arbitrarily slow loading rates, in particular loading rates achievable in the laboratory, and suffers from none of the limitations in this regard inherent in MD simulations.

  7. Design of a compact mode and polarization converter in three-dimensional photonic crystals.

    PubMed

    Wang, Jian; Qi, Minghao

    2012-08-27

    A mode and polarization converter is proposed and optimized for 3D photonic integrated circuits based on photonic crystals (PhCs). The device converts the index-guided TE mode of a W1 solid-core (SC) waveguide to the band-gap-guided TM mode of a W1 hollow-core (HC) waveguide in 3D PhCs, and vice versa. The conversion is achieved based on contra-directional mode coupling. For a 25 μm-long device, simulations show that the power conversion efficiency is over 98% across a wavelength range of 16 nm centered at 1550 nm, whereas the reflection remains below -20 dB. The polarization extinction ratio of the conversion is in principle infinitely high because both W1 waveguides operate in the single-mode regimes in this wavelength range.

  8. Optoelectronic optimization of mode selective converter based on liquid crystal on silicon

    NASA Astrophysics Data System (ADS)

    Wang, Yongjiao; Liang, Lei; Yu, Dawei; Fu, Songnian

    2016-03-01

    We carry out comprehensive optoelectronic optimization of mode selective converter used for the mode division multiplexing, based on liquid crystal on silicon (LCOS) in binary mode. The conversion error of digital-to-analog (DAC) is investigated quantitatively for the purpose of driving the LCOS in the application of mode selective conversion. Results indicate the DAC must have a resolution of 8-bit, in order to achieve high mode extinction ratio (MER) of 28 dB. On the other hand, both the fast axis position error of half-wave-plate (HWP) and rotation angle error of Faraday rotator (FR) have negative influence on the performance of mode selective conversion. However, the commercial products provide enough angle error tolerance for the LCOS-based mode selective converter, taking both of insertion loss (IL) and MER into account.

  9. NONLINEAR OPTICAL PHENOMENA: Peculiarites of second harmonic generation of radiation from a pulsed ytterbium-doped fibre laser in KTiOPO4 crystals

    NASA Astrophysics Data System (ADS)

    Davydov, B. L.; Krylov, Aleksandr A.

    2007-07-01

    Second harmonic generation of radiation from a high-power fibre Yb3+ laser is studied upon sf—f phase matching near the X axis of the KTP crystal (KTiOPO4). The temperature dependence of the phase-matching wavelength as well as its spectral, angular and temperature tuning characteristics of the second harmonic generator are experimentally measured. It is found that the increase in the average output power of the second harmonic in a single crystal is limited, first of all, by the thermal self-focusing of radiation caused by the absorption of radiation from the second harmonic, whose threshold decreases with increasing the crystal temperature. When the two-channel scheme is used, the maximum stable ~4-W output power of the second harmonic is obtained in two tandem KTP crystals.

  10. Organic salts of biguanide - An attempt to crystal engineering of novel materials for second harmonic generation

    NASA Astrophysics Data System (ADS)

    Matulková, Irena; Němec, Ivan; Císařová, Ivana; Němec, Petr; Vaněk, Přemysl

    2010-03-01

    Three organic salts of biguanide with oxalic, succinic and L-tartaric acids have been prepared and X-ray structural analysis has been performed. Biguanidium(1+) oxalate hemihydrate ( a = 6.8330(2) Å, b = 10.0430(2) Å, c = 14.6230(4) Å, α = 90.236(1) , β = 90.333(1) , γ = 105.605(2) , V = 966.46(4) Å 3, Z = 1, R = 0.0393 for 3704 observed reflections) and biguanidium(1+) hydrogen succinate ( a = 6.4600(1) Å, b = 6.7670(2) Å, c = 11.4150(3) Å, α = 91.822(1) , β = 105.312(1) , γ = 90.922(1) , V = 480.89(2) Å 3, Z = 2, R = 0.0357 for 1880 observed reflections) belong to the triclinic space group P 1¯. Their crystal structures are based on biguanidium(1+) pairs connected by intermolecular N-H⋯N hydrogen bonds. The remaining ions (eventually water molecules) form a 3D structural network with these pairs. Furthermore, the formation of the cationic and anionic layers interconnected by intermolecular N-H⋯O hydrogen bonds was observed in the crystal structure of biguanidium(1+) hydrogen succinate. Biguanidium(2+) L-tartrate crystallizes in the orthorhombic space group P 2 12 12 1 ( a = 6.7170(2) Å, b = 9.2740(2) Å, c = 16.1500(4) Å, V = 1006.04(4) Å 3, Z = 4, R = 0.0432 for 2193 observed reflections). The crystal structure is based on L-tartrate chains, which are interconnected by isolated biguanidium(2+) cations via several types of N-H⋯O hydrogen bonds. The formation of L-tartrate chains is mediated by two types of intermolecular O-H⋯O hydrogen bonds connecting the hydroxyl and carboxylate groups. The FTIR and FT Raman spectra of all the compounds were recorded and discussed. The theoretical values of the first hyperpolarizability components were calculated for biguanidium(1+) and biguanidium(2+) cations at the B3LYP level with the 6-311G(d,p) basis set. Quantitative measurements of the second harmonic generation of powdered biguanidium(2+) L-tartrate at 800 nm were performed and a relative efficiency of 2% (compared to KDP) was

  11. Optical second-harmonic generation from two-dimensional hexagonal crystals with broken space inversion symmetry.

    PubMed

    Margulis, Vl A; Muryumin, E E; Gaiduk, E A

    2013-05-15

    We propose a microscopic theory of the optical second-harmonic generation (SHG) from π electrons in two-dimensional (2D) honeycomb lattice structures with broken space inversion symmetry, such as graphene epitaxially grown on a SiC substrate and boronitrene (a single sheet of hexagonal boron nitride (h-BN)). The approach developed is based on a simple two-band π-electron tight-binding model combined with the original Genkin-Mednis formalism of the second-order nonlinear optical response theory, detailed in our recent paper (2010 Phys. Rev. B 82 235426). Within the framework of the approach, we derive an explicit expression for the SHG susceptibility χ2(SHG(ω), which involves two distinct contributions originating from a mixture of interband and intraband motion of π electrons. Both the contributions, and, hence, the χ2(SHG(ω) on the whole, are found to tend to zero when the π-electron energy bands involved are treated at the simplest level of approximation, neglecting the effect of their trigonal warping around the corners of the Brillouin zone of the 2D hexagonal lattice. Through numerical calculations, it is shown that this effect, though rather small, leads to a fairly large magnitude of the SHG susceptibility, reaching the order of 10(-4) esu for the graphene/SiC overlayer system and 10(-7) esu for monolayer h-BN, when the pump photon energy ħω approaches half the bandgap energy Eg of those structures. These theoretical findings suggest that SHG can be used as a sensitive optical probe of the electronic structure of the examined 2D hexagonal crystals and simultaneously demonstrate that those crystals may be an appropriate material for practical uses in future optoelectronic nano-devices.

  12. Heat transport and phonon localization in mass-disordered harmonic crystals

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Abhishek; Kundu, Anupam; Roy, Dibyendu; Dhar, Abhishek; Lebowitz, Joel L.; Spohn, Herbert

    2010-02-01

    We investigate the steady-state heat current in two- and three-dimensional disordered harmonic crystals in a slab geometry connected at the boundaries to stochastic white-noise heat baths at different temperatures. The disorder causes short-wavelength phonon modes to be localized so the heat current in this system is carried by the extended phonon modes which can be either diffusive or ballistic. Using ideas both from localization theory and from kinetic theory we estimate the contribution of various modes to the heat current and from this we obtain the asymptotic system size dependence of the current. These estimates are compared with results obtained from a numerical evaluation of an exact formula for the current, given in terms of a frequency-transmission function, as well as from direct nonequilibrium simulations. These yield a strong dependence of the heat flux on boundary conditions. Our analytical arguments show that for realistic boundary conditions the conductivity is finite in three dimensions but we are not able to verify this numerically, except in the case where the system is subjected to an external pinning potential. This case is closely related to the problem of localization of electrons in a random potential and here we numerically verify that the pinned three-dimensional system satisfies Fourier’s law while the two-dimensional system is a heat insulator. We also investigate the inverse participation ratio of different normal modes.

  13. Chirped photonic crystal mode converters for broad-band coupling with highly dispersive photonic crystal microring resonators

    NASA Astrophysics Data System (ADS)

    Lo, Stanley M.; Lee, Jonathan Y.; Weiss, Sharon M.; Fauchet, Philippe M.

    2014-03-01

    We demonstrate evanescent coupling between a photonic crystal (PhC) waveguide and a PhC embedded microring resonator on the silicon-on-insulator platform. The mode converter comprises 6 linearly chirped air holes that adiabatically couple the light between the silicon waveguide mode and the PhC mode. Three-dimensional finitedifference time-domain simulations reveal a coupling bandwidth of >100nm. From our experiment, the optical spectra show a photonic bandgap located below ~1590nm. At the resonances in the slow-light regime, a loaded quality factor as high as ~2500 was measured and a group index of ~16 in the PhC embedded microring resonator was estimated from the non-uniform free spectral ranges.

  14. Temperature-Frequency Converter Using a Liquid Crystal Cell as a Sensing Element

    PubMed Central

    Marcos, Carlos; Sánchez Pena, José M.; Torres, Juan C.; Santos, José Isidro

    2012-01-01

    A new temperature-frequency converter based on the variation of the dielectric permittivity of the Liquid Crystal (LC) material with temperature has been demonstrated. Unlike other temperature sensors based on liquid crystal processing optical signals for determining the temperature, this work presents a system that is able to sense temperature by using only electrical signals. The variation of the dielectric permittivity with temperature is used to modify the capacitance of a plain capacitor using a LC material as non-ideal dielectric. An electric oscillator with an output frequency depending on variable capacitance made of a twisted-nematic (TN) liquid crystal (LC) cell has been built. The output frequency is related to the temperature of LC cell through the equations associated to the oscillator circuit. The experimental results show excellent temperature sensitivity, with a variation of 0.40% of the initial frequency per degree Celsius in the temperature range from −6 °C to 110 °C. PMID:22737002

  15. Antimicrobial activity and second harmonic studies on organic non-centrosymmetric pure and doped ninhydrin single crystals

    NASA Astrophysics Data System (ADS)

    Prasanyaa, T.; Jayaramakrishnan, V.; Haris, M.

    2013-03-01

    In this paper, we report the successful growth of pure, Cu2+ ions and Cd2+ ions doped on ninhydrin single crystals by slow solvent evaporation technique. The presence of Cu2+ and Cd2+ ions in the specimen of ninhydrin single crystal has been determined by atomic absorption spectroscopy. The powder X-ray diffraction analysis was done to calculate the lattice parameters of the pure and doped crystals. The percentage of transmittance of the crystal was recorded using the UV-Vis Spectrophotometer. Thermal behaviors of the grown crystals have been examined by the thermal gravimetric/differential thermal analysis. The hardness of the grown crystals was assessed and the results show the minor variation in the hardness value for the pure and doped ninhydrin samples. The value of the work hardening coefficient n was found to be 2.0, 1.0 and 1.06 for pure, copper and cadmium doped ninhydrin crystals respectively. The second harmonic generation efficiency of Cd2+ and Cu2+ doped ninhydrin is 8.3 and 6.3 times greater than well known nonlinear crystal of potassium dihydrogen phosphate respectively. The antibacterial and antifungal activities of the title compound were performed by disk diffusion method against the standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillis niger and Aspergillus flavus.

  16. Green up-converted luminescence in (Er3+-Yb3+) co-doped LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Stoffel, M.; Rinnert, H.; Kokanyan, E.; Demirkhanyan, G.; Demirkhanyan, H.; Aillerie, M.

    2016-07-01

    Er3+ doped and (Er3+-Yb3+) co-doped LiNbO3 (LN) crystals grown by the Czochralski method are investigated by photoluminescence spectroscopy. Green up-converted luminescence is observed in Er3+ doped LN crystals under 980 nm excitation. This is explained by an energy transfer between two neighboring Er3+ ions. In (Er3+, Yb3+) co-doped LN crystals, the intensity of the green up-converted luminescence can be further enhanced suggesting that Yb3+ ions also contribute to the up-conversion process. Time resolved photoluminescence measurements clearly demonstrate that an efficient energy transfer occurs between Yb3+ and Er3+ ions. A theoretical model taking into account the contribution of both Er3+-Er3+ pairs and Yb3+-Er3+ pairs is able to describe correctly the decay of the up-converted luminescence.

  17. High harmonic generation in a gas-filled hollow-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Heckl, O. H.; Baer, C. R. E.; Kränkel, C.; Marchese, S. V.; Schapper, F.; Holler, M.; Südmeyer, T.; Robinson, J. S.; Tisch, J. W. G.; Couny, F.; Light, P.; Benabid, F.; Keller, U.

    2009-10-01

    High harmonic generation (HHG) of intense infrared laser radiation (Ferray et al., J. Phys. B: At. Mol. Opt. Phys. 21:L31, 1988; McPherson et al., J. Opt. Soc. Am. B 4:595, 1987) enables coherent vacuum-UV (VUV) to soft-X-ray sources. In the usual setup, energetic femtosecond laser pulses are strongly focused into a gas jet, restricting the interaction length to the Rayleigh range of the focus. The average photon flux is limited by the low conversion efficiency and the low average power of the complex laser amplifier systems (Keller, Nature 424:831, 2003; Südmeyer et al., Nat. Photonics 2:599, 2008; Röser et al., Opt. Lett. 30:2754, 2005; Eidam et al., IEEE J. Sel. Top. Quantum Electron. 15:187, 2009) which typically operate at kilohertz repetition rates. This represents a severe limitation for many experiments using the harmonic radiation in fields such as metrology or high-resolution imaging. Driving HHG with novel high-power diode-pumped multi-megahertz laser systems has the potential to significantly increase the average photon flux. However, the higher average power comes at the expense of lower pulse energies because the repetition rate is increased by more than a thousand times, and efficient HHG is not possible in the usual geometry. So far, two promising techniques for HHG at lower pulse energies were developed: external build-up cavities (Gohle et al., Nature 436:234, 2005; Jones et al., Phys. Rev. Lett. 94:193, 2005) and resonant field enhancement in nanostructured targets (Kim et al., Nature 453:757, 2008). Here we present a third technique, which has advantages in terms of ease of HHG light extraction, transverse beam quality, and the possibility to substantially increase conversion efficiency by phase-matching (Paul et al., Nature 421:51, 2003; Ren et al., Opt. Express 16:17052, 2008; Serebryannikov et al., Phys. Rev. E (Stat. Nonlinear Soft Matter Phys.) 70:66611, 2004; Serebryannikov et al., Opt. Lett. 33:977, 2008; Zhang et al., Nat. Phys. 3

  18. High-Efficiency Broadband High-Harmonic Generation from a Single Quasi-Phase-Matching Nonlinear Crystal.

    PubMed

    Chen, Bao-Qin; Zhang, Chao; Hu, Chen-Yang; Liu, Rong-Juan; Li, Zhi-Yuan

    2015-08-21

    Nonlinear frequency conversion offers an effective way to expand the laser wavelength range based on birefringence phase matching (BPM) or quasi-phase-matching (QPM) techniques in nonlinear crystals. So far, efficient high-harmonic generation is enabled only via multiple cascaded crystals because of the extreme difficulty to simultaneously satisfy BPM or QPM for multiple nonlinear up-conversion processes within a single crystal. Here we report the design and fabrication of a chirped periodic poled lithium niobate (CPPLN) nonlinear crystal that offers controllable multiple QPM bands to support 2nd-8th harmonic generation (HG) simultaneously. Upon illumination of a mid-IR femtosecond pulse laser, we observe the generation of an ultrabroadband visible white light beam corresponding to 5th-8th HG with a record high conversion efficiency of 18%, which is high compared to conventional supercontinuum generation, especially in the HG parts. Our CPPLN scheme opens up a new avenue to explore and engineer novel nonlinear optical interactions in solid state materials for application in ultrafast lasers and broadband laser sources. PMID:26340190

  19. High-Efficiency Broadband High-Harmonic Generation from a Single Quasi-Phase-Matching Nonlinear Crystal.

    PubMed

    Chen, Bao-Qin; Zhang, Chao; Hu, Chen-Yang; Liu, Rong-Juan; Li, Zhi-Yuan

    2015-08-21

    Nonlinear frequency conversion offers an effective way to expand the laser wavelength range based on birefringence phase matching (BPM) or quasi-phase-matching (QPM) techniques in nonlinear crystals. So far, efficient high-harmonic generation is enabled only via multiple cascaded crystals because of the extreme difficulty to simultaneously satisfy BPM or QPM for multiple nonlinear up-conversion processes within a single crystal. Here we report the design and fabrication of a chirped periodic poled lithium niobate (CPPLN) nonlinear crystal that offers controllable multiple QPM bands to support 2nd-8th harmonic generation (HG) simultaneously. Upon illumination of a mid-IR femtosecond pulse laser, we observe the generation of an ultrabroadband visible white light beam corresponding to 5th-8th HG with a record high conversion efficiency of 18%, which is high compared to conventional supercontinuum generation, especially in the HG parts. Our CPPLN scheme opens up a new avenue to explore and engineer novel nonlinear optical interactions in solid state materials for application in ultrafast lasers and broadband laser sources.

  20. High-Efficiency Broadband High-Harmonic Generation from a Single Quasi-Phase-Matching Nonlinear Crystal

    NASA Astrophysics Data System (ADS)

    Chen, Bao-Qin; Zhang, Chao; Hu, Chen-Yang; Liu, Rong-Juan; Li, Zhi-Yuan

    2015-08-01

    Nonlinear frequency conversion offers an effective way to expand the laser wavelength range based on birefringence phase matching (BPM) or quasi-phase-matching (QPM) techniques in nonlinear crystals. So far, efficient high-harmonic generation is enabled only via multiple cascaded crystals because of the extreme difficulty to simultaneously satisfy BPM or QPM for multiple nonlinear up-conversion processes within a single crystal. Here we report the design and fabrication of a chirped periodic poled lithium niobate (CPPLN) nonlinear crystal that offers controllable multiple QPM bands to support 2nd-8th harmonic generation (HG) simultaneously. Upon illumination of a mid-IR femtosecond pulse laser, we observe the generation of an ultrabroadband visible white light beam corresponding to 5th-8th HG with a record high conversion efficiency of 18%, which is high compared to conventional supercontinuum generation, especially in the HG parts. Our CPPLN scheme opens up a new avenue to explore and engineer novel nonlinear optical interactions in solid state materials for application in ultrafast lasers and broadband laser sources.

  1. Ultra-compact photonic crystal waveguide spatial mode converter and its connection to the optical diode effect.

    PubMed

    Liu, Victor; Miller, David A B; Fan, Shanhui

    2012-12-17

    We design an extremely compact photonic crystal waveguide spatial mode converter which converts the fundamental even mode to the higher order odd mode with nearly 100% efficiency. We adapt a previously developed design and optimization process that allows these types of devices to be designed in a matter of minutes. We also present an extremely compact optical diode device and clarify its general properties and its relation to spatial mode converters. Finally, we connect the results here to a general theory on the complexity of optical designs.

  2. Generation of third harmonic picosecond pulses at 355 nm by sum frequency mixing in periodically poled MgSLT crystal

    NASA Astrophysics Data System (ADS)

    Kaltenbach, André; Schönau, Thomas; Lauritsen, Kristian; Tränkle, Günther; Erdmann, Rainer

    2015-02-01

    Third harmonic 355nm picosecond pulses are generated by sum frequency mixing in a periodically poled magnesium doped stoichiometric lithium tantalate (PPMgSLT) crystal. The third harmonic generation is based on the 1064nm radiation of a gain-switched distributed feedback (DFB) diode laser which is amplified by a two-stage fiber amplifier. The diode laser is freely triggerable at variable repetition rates up to 80MHz and provides optical pulses of 65 ps FWHM duration and pulse energies in the range of 5 pJ. The 355nm third harmonic generation is realized in a two-step conversion process. First, the 1064nm fundamental radiation is frequency-doubled to 532 nm, afterwards both frequencies are mixed in the PPMgSLT crystal to 355 nm. The UV-radiation shows a pulse width of 60 ps, a good beam profile and stable pulse energy over a wide range of repetition rates by proprietary pump power management. At 355nm a pulse peak power of 5.3W was achieved with 192W pulse peak power of the fundamental radiation.

  3. The optimum configuration for the third-harmonic generation of 1.064 μm in a YCOB crystal

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Fu, K.; Xu, X.; Sun, X.; Jiang, H.; Song, R.; Liu, J.; Wang, J.; Liu, Y.; Wei, J.; Shao, Z.

    A method of determining the spatial configuration of a YCa4O(BO3)3 (YCOB) crystal is introduced. The type-I phase-matching points for the sum-frequency of 1.064 μm and 0.532 μm, as well as the conversion efficiency for YCOB samples cut in different directions, have been measured. When the input intensity is 0.76 GW/cm2, the third-harmonic generation (THG) conversion efficiency for the (106°, 77.2°)-cut YCOB crystal reaches 26.2%, which is the highest that we know so far. Both the calculations and the experiments show that the optimum THG configuration for a YCOB crystal is near (106°, 77.2°), or other equivalent directions in space.

  4. Manifestation of quantum disordered wave functions with weak localization from conical second harmonic generation in ferroelectric crystal

    NASA Astrophysics Data System (ADS)

    Yu, H. H.; Zhang, H. J.; Wang, Z. P.; Xu, H. H.; Wang, Y. C.; Wang, J. Y.; Petrov, V.

    2012-02-01

    The spatial structure of two-dimensional quantum disordered wave functions with weak localization (WL) is experimentally observed using a calcium barium niobate Ca0.28Ba0.72Nb2O6 (CBN-28) ferroelectric crystal illuminated by a pulsed laser beam. Non-collinear phase-matching in CBN-28 produces conical second harmonic pattern in the far-field. The probability density distribution of the experimental near-field pattern agrees very well with the theoretical predictions. The localization degree, within the error limits, is the same at different transverse positions due to the periodicity of the crystal and the eigenfunctions are degenerated. We conclude that a ferroelectric crystal represents an ideal model system for investigation of WL.

  5. Second-harmonic generation in quaternary atomically thin layered AgInP2S6 crystals

    NASA Astrophysics Data System (ADS)

    Wang, Xingzhi; Du, Kezhao; Liu, Weiwei; Hu, Peng; Lu, Xin; Xu, Weigao; Kloc, Christian; Xiong, Qihua

    2016-09-01

    Nonlinear effects in two-dimensional (2D) atomic layered materials have attracted increasing interest. Here, we report the observation of optical second-harmonic generation (SHG) in two-dimensional atomically thin silver indium phosphorus sulfide (AgInP2S6) crystals, with odd layer thickness. The nonlinear signal facilitates the use of thickness-dependent SHG intensity to investigate the stacking type of this material, while the crystal-orientation dependent SHG intensity of the monolayer sample reveals the rotational symmetry of the AgInP2S6 lattice in plane. Our studies expand the 2D crystal family in nonlinear effect field, which opened considerable promise to the functionalities and potential applications of 2D materials.

  6. Growth and characterization of crystals for IR detectors and second harmonic gereration devices

    NASA Technical Reports Server (NTRS)

    Lal, Ravi B.; Batra, Ashok K.; Rao, Sistla M.; Bhatia, S. S.; Chunduru, Kunar P.; Paulson, Ron; Moorkherji, Tripty K.

    1989-01-01

    Two types of materials, L-arginine phosphate (LAP) and doped triglycine sulfate (TGS), are examined for their growth characteristics and relevant properties for second harmonic generation and IR detector applications, respectively.

  7. Improved frequency/voltage converters for fast quartz crystal microbalance applications

    SciTech Connect

    Torres, R.; Kim, L. To Thi; Garcia, J. V.; Arnau, A.

    2008-04-15

    The monitoring of frequency changes in fast quartz crystal microbalance (QCM) applications is a real challenge in today's instrumentation. In these applications, such as ac electrogravimetry, small frequency shifts, in the order of tens of hertz, around the resonance of the sensor can occur up to a frequency modulation of 1 kHz. These frequency changes have to be monitored very accurately both in magnitude and phase. Phase-locked loop techniques can be used for obtaining a high performance frequency/voltage converter which can provide reliable measurements. Sensitivity higher than 10 mV/Hz, for a frequency shift resolution of 0.1 Hz, with very low distortion in tracking both the magnitude and phase of the frequency variations around the resonance frequency of the sensor are required specifications. Moreover, the resonance frequency can vary in a broad frequency range from 5 to 10 MHz in typical QCM sensors, which introduces an additional difficulty. A new frequency-voltage conversion system based on a double tuning analog-digital phase-locked loop is proposed. The reported electronic characterization and experimental results obtained with conducting polymers prove its reliability for ac-electrogravimetry measurements and, in general, for fast QCM applications.

  8. Numerical analysis of second harmonic generation for THz-wave in a photonic crystal waveguide using a nonlinear FDTD algorithm

    NASA Astrophysics Data System (ADS)

    Saito, Kyosuke; Tanabe, Tadao; Oyama, Yutaka

    2016-04-01

    We have presented a numerical analysis to describe the behavior of a second harmonic generation (SHG) in THz regime by taking into account for both linear and nonlinear optical susceptibility. We employed a nonlinear finite-difference-time-domain (nonlinear FDTD) method to simulate SHG output characteristics in THz photonic crystal waveguide based on semi insulating gallium phosphide crystal. Unique phase matching conditions originated from photonic band dispersions with low group velocity are appeared, resulting in SHG output characteristics. This numerical study provides spectral information of SHG output in THz PC waveguide. THz PC waveguides is one of the active nonlinear optical devices in THz regime, and nonlinear FDTD method is a powerful tool to design photonic nonlinear THz devices.

  9. Generation of arbitrary vector beams with liquid crystal polarization converters and vector-photoaligned q-plates

    SciTech Connect

    Chen, Peng; Ji, Wei; Wei, Bing-Yan; Hu, Wei Lu, Yan-Qing; Chigrinov, Vladimir

    2015-12-14

    Arbitrary vector beams (VBs) are realized by the designed polarization converters and corresponding vector-photoaligned q-plates. The polarization converter is a specific twisted nematic cell with one substrate homogeneously aligned and the other space-variantly aligned. By combining a polarization-sensitive alignment agent with a dynamic micro-lithography system, various categories of liquid crystal polarization converters are demonstrated. Besides, traditional radially/azimuthally polarized light, high-order and multi-ringed VBs, and a VB array with different orders are generated. The obtained converters are further utilized as polarization masks to implement vector-photoaligning. The technique facilitates both the volume duplication of these converters and the generation of another promising optical element, the q-plate, which is suitable for the generation of VBs for coherent lasers. The combination of proposed polarization converters and correspondingly fabricated q-plates would drastically enhance the capability of polarization control and may bring more possibilities for the design of photonic devices.

  10. Crystalline perfection, optical and third harmonic generation analyses of non-linear optical single crystal of L-lysine acetate.

    PubMed

    Rani, Neelam; Vijayan, N; Thukral, Kanika; Maurya, K K; Haranath, D; Bhagavannarayana, G; Verma, S; Wahab, M A

    2013-03-15

    The potential organic non-linear optical single crystal of L-lysine acetate has been grown by slow evaporation solution growth technique (SEST) at room temperature. It crystallizes in the monoclinic system with space group of P2(1). The crystalline perfection of the grown single crystal has been examined by high resolution X-ray diffraction analysis (HRXRD). The functional groups of the synthesized compound have been identified by (13)C NMR, (1)H NMR and FTIR analyses. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut-off wavelength of 236 nm. The optical band gap is found to be 5.29 eV. The steady-state PL spectra was recorded for pure L-lysine acetate crystal at room temperature. The third harmonic generation efficiency of the crystal has been evaluated by Z-scan technique and its non-linear optical coefficient has been calculated. Birefringence measurement has been carried out in order to see the optical homogeneity of the grown specimen. Its electrical properties has been assessed by dielectric measurement at different temperatures. The calculated optical band gap is 5.29 eV. Its thermal parameters like thermal diffusivity (α), thermal effusivity (e), thermal conductivity (k) and heat capacity (C(p)) have been determined by photopyroelectric technique. Vickers micro hardness studies were carried out using a Vickers hardness tester equipped with a diamond square indenter. The piezoelectric measurement for L-lysine acetate has been also been carried at ambient condition.

  11. In-plane time-harmonic elastic wave motion and resonance phenomena in a layered phononic crystal with periodic cracks.

    PubMed

    Golub, Mikhail V; Zhang, Chuanzeng

    2015-01-01

    This paper presents an elastodynamic analysis of two-dimensional time-harmonic elastic wave propagation in periodically multilayered elastic composites, which are also frequently referred to as one-dimensional phononic crystals, with a periodic array of strip-like interior or interface cracks. The transfer matrix method and the boundary integral equation method in conjunction with the Bloch-Floquet theorem are applied to compute the elastic wave fields in the layered periodic composites. The effects of the crack size, spacing, and location, as well as the incidence angle and the type of incident elastic waves on the wave propagation characteristics in the composite structure are investigated in details. In particular, the band-gaps, the localization and the resonances of elastic waves are revealed by numerical examples. In order to understand better the wave propagation phenomena in layered phononic crystals with distributed cracks, the energy flow vector of Umov and the corresponding energy streamlines are visualized and analyzed. The numerical results demonstrate that large energy vortices obstruct elastic wave propagation in layered phononic crystals at resonance frequencies. They occur before the cracks reflecting most of the energy transmitted by the incoming wave and disappear when the problem parameters are shifted from the resonant ones.

  12. Repetitively pulsed TEA CO2 laser and its application for second harmonic generation in ZnGeP2 crystal

    NASA Astrophysics Data System (ADS)

    Koval'chuk, L. V.; Grezev, A. N.; Niz'ev, V. G.; Yakunin, V. P.; Mezhevov, V. S.; Goryachkin, D. A.; Sergeev, V. V.; Kalintsev, A. G.

    2015-10-01

    Experimental results are presented on the development of a radiation source emitting at a wavelength of 4.775 μm with a pulse energy up to 50 mJ and an average power up to several watts in short pulse trains. A TEA CO2 laser and a nonlinear converter based on a ZnGeP2 crystal, which are specially designed for these experiments, are described. The main limitations of nonlinear conversion and possible ways to overcome these limitations are considered.

  13. Laue diffraction in one-dimensional photonic crystals: The way for phase-matched second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Novikov, V. B.; Maydykovskiy, A. I.; Mantsyzov, B. I.; Murzina, T. V.

    2016-06-01

    Phase-matched second-harmonic generation (SHG) under the Bragg diffraction in the Laue geometry in one-dimensional photonic crystal (PhC) is studied theoretically and experimentally. We demonstrate that the phase-matched SHG can be realized in a PhC by compensation of the material dispersion of the PhC constituent layers of adjustable thickness. The second-order nonlinear susceptibility is introduced in the porous quartz-based PhC by its infiltration by sodium nitrite. We observed that two second-harmonic (SH) beams appear after passing through the PhC under the phase-matched process, which correspond to the transmission and diffraction angular directions. The appearance of the phase-matched SHG is confirmed by a pronounced SH spectral dependence and a narrow SH angular distribution, with the FWHM of the SH peak of approximately 3.5 times smaller as compared to the case of non-phase-matched SHG.

  14. Precise, motion-free polarization control in Second Harmonic Generation microscopy using a liquid crystal modulator in the infinity space.

    PubMed

    Lien, Chi-Hsiang; Tilbury, Karissa; Chen, Shean-Jen; Campagnola, Paul J

    2013-01-01

    Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies.

  15. Enhancement of second harmonic generation in NaNO2-infiltrated opal photonic crystal using structural light focusing

    NASA Astrophysics Data System (ADS)

    Zaytsev, Kirill I.; Yurchenko, Stanislav O.

    2014-08-01

    Experimental and numerical results for second harmonic generation (SHG) in photonic crystal (PC) based on NaNO2-infiltrated opal matrix are presented. SHG is performed in reflection mode; thus, the direction of the SHG maximum is equal to the angle of mirror reflection. The PC was pumped with femtosecond optical pulses at different angles of incidence, allowing the dependence of the SHG efficiency on the location of the fundamental wavelength toward the PC band gap (BG) to be examined. The most efficient SHG was observed when pumping the BG of the PC. To interpret the experimental results, finite-difference time-domain numerical simulations of the light interaction with the PC were conducted. The observed effect of highly efficient SHG is associated with structural light focusing, and, as a consequence, with strong optical field localization within certain near-surface PC regions. Thus, SHG enhancement based on structural light focusing in PC was demonstrated.

  16. Observation of optical second-harmonic generation in porous-silicon-based photonic crystals in the Laue diffraction scheme

    NASA Astrophysics Data System (ADS)

    Kopylov, D. A.; Svyakhovskiy, S. E.; Dergacheva, L. V.; Bushuev, V. A.; Mantsyzov, B. I.; Murzina, T. V.

    2016-05-01

    Second-harmonic generation (SHG) in the Laue scheme of the dynamical Bragg diffraction in one-dimensional photonic crystal (PhC) is studied. The experiments are performed for partially annealed porous-silicon PhC containing 250 periods of the structure. Our measurements confirm that the phase-matched optical SHG is observed under the Bragg conditions, which is evidenced by a narrow angular and spectral distribution of the diffracted SHG outgoing the PhC. This is confirmed by both the analytical description of the SHG process performed in the two-wave approximation, and by direct calculations of the PhC dispersion curves for the fundamental and SHG wavelengths by the revised plane wave method. Possible types of phase- and quasi-phase-matching realized in the studied PhC under the Laue diffraction scheme are discussed.

  17. Enhancement of second harmonic generation in NaNO{sub 2}-infiltrated opal photonic crystal using structural light focusing

    SciTech Connect

    Zaytsev, Kirill I. Yurchenko, Stanislav O.

    2014-08-04

    Experimental and numerical results for second harmonic generation (SHG) in photonic crystal (PC) based on NaNO{sub 2}-infiltrated opal matrix are presented. SHG is performed in reflection mode; thus, the direction of the SHG maximum is equal to the angle of mirror reflection. The PC was pumped with femtosecond optical pulses at different angles of incidence, allowing the dependence of the SHG efficiency on the location of the fundamental wavelength toward the PC band gap (BG) to be examined. The most efficient SHG was observed when pumping the BG of the PC. To interpret the experimental results, finite-difference time-domain numerical simulations of the light interaction with the PC were conducted. The observed effect of highly efficient SHG is associated with structural light focusing, and, as a consequence, with strong optical field localization within certain near-surface PC regions. Thus, SHG enhancement based on structural light focusing in PC was demonstrated.

  18. Simultaneous negative refraction and focusing of fundamental frequency and second-harmonic fields by two-dimensional photonic crystals

    SciTech Connect

    Zhang, Jun; Zhang, Xiangdong

    2015-09-28

    Simultaneous negative refraction for both the fundamental frequency (FF) and second-harmonic (SH) fields in two-dimensional nonlinear photonic crystals have been found through both the physical analysis and exact numerical simulation. By combining such a property with the phase-matching condition and strong second-order susceptibility, we have designed a SH lens to realize focusing for both the FF and SH fields at the same time. Good-quality non-near field images for both FF and SH fields have been observed. The physical mechanism for such SH focusing phenomena has been disclosed, which is different from the backward SH generation as has been pointed out in the previous investigations. In addition, the effect of absorption losses on the phenomena has also been discussed. Thus, potential applications of these phenomena to biphotonic microscopy technique are anticipated.

  19. Electro-optic harmonic conversion to switch a laser beam out of a cavity

    DOEpatents

    Haas, Roger A.; Henesian, Mark A.

    1987-01-01

    The invention is a switch to permit a laser beam to escape a laser cavity through the use of an externally applied electric field across a harmonic conversion crystal. Amplification takes place in the laser cavity, and then the laser beam is switched out by the laser light being harmonically converted with dichroic or polarization sensitive elements present to alter the optical path of the harmonically converted laser light. Modulation of the laser beam can also be accomplished by varying the external electric field.

  20. Investigation about relationships between the symmetries of ferroelectric crystal Ca0.28Ba0.72Nb2O6 and second-harmonic patterns

    NASA Astrophysics Data System (ADS)

    Xu, Tianxiang; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2015-08-01

    The broadband quasi-phase matching (QPM) process in a uniaxial ferroelectric crystal Ca0.28Ba0.72Nb2O6 (CBN-28) was demonstrated with the second-harmonic wavelength range from 450 nm to 650 nm, and the relationship between the symmetries of CBN-28 and the second-harmonic patterns was experimentally and theoretically investigated based on the random anti-parallel domains in the crystal and QPM conditions. The dependences of frequency-doubled patterns on the wavelength and anisotropy of the nonlinear crystal were also studied, and the frequency-doubled photons were found to be trapped on circles. By analyzing the light-matter interacting Hamiltonians, the trapping force for second-harmonic photons was found to be centripetal and tunable by the fundamental lasers, and the variation tendencies of the rotational velocity of second-harmonic generation photons could also be predicated. The results indicate that the CBN-28 ferroelectric crystal is a promising nonlinear optical material for the generation of broadband frequency-doubled waves, and the analysis on centripetal force based on the interaction Hamiltonians may provide a novel recognition for the investigation of QPM process to be further studied.

  1. Crystallization and second harmonic generation in potassium-sodium niobiosilicate glasses

    SciTech Connect

    Aronne, Antonio; Fanelli, Esther; Pernice, Pasquale; Peli, Simone; Giannetti, Claudio; Ferrini, Gabriele

    2009-10-15

    Transparent glasses having molar composition (23-x)K{sub 2}O.xNa{sub 2}O.27Nb{sub 2}O{sub 5}.50SiO{sub 2} (x=0, 5, 10, 15 and 23) have been synthesized by the melt-quenching technique and their devitrification behaviour has been investigated by DTA and XRD. Depending on the composition, the glasses showed a glass transition temperature in the range 660-680 deg. C and devitrified in several steps. XRD measurements showed that the replacement of K{sub 2}O by Na{sub 2}O strongly affects the crystallization behaviour. Particularly, in the glasses with only potassium or low sodium content the first devitrification step is related to the crystallization of an unidentified phase, while in the glass containing only sodium, NaNbO{sub 3} crystallizes. For an intermediate sodium content (x=10 and 15) a potassium sodium niobate crystalline phase, belonging to the tungsten-bronze family, is formed by bulk nucleation. This system looks promising to produce active nanostructured glasses as the tungsten-bronze type crystals have ferroelectric, electro-optical and non-linear optical properties. Preliminary measurements evidenced SHG activity in the crystallized glasses containing this phase. - Graphical abstract: Synthesis of glasses (23-x)K{sub 2}O.xNa{sub 2}O.27Nb{sub 2}O{sub 5}.50SiO{sub 2} (x=0, 5, 10, 15 and 23) from which SHG active phases crystallize by bulk nucleation for non-linear optical nanostructured glasses.

  2. XTL Converter

    SciTech Connect

    Spurgeon, Steven R

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious; it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Header information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.

  3. XTL Converter

    2015-10-07

    "XTL Converter" is a short Python script for electron microscopy simulation. The program takes an input crystal file in the VESTA *.XTL format and converts it to a text format readable by the multislice simulation program ìSTEM. The process of converting a crystal *.XTL file to the format used by the ìSTEM simulation program is quite tedious; it generally requires the user to select dozens or hundreds of atoms, rearranging and reformatting their position. Headermore » information must also be reformatted to a specific style to be read by ìSTEM. "XTL Converter" simplifies this process, saving the user time and allowing for easy batch processing of crystals.« less

  4. Ultra-compact broadband mode converter and optical diode based on linear rod-type photonic crystal waveguide.

    PubMed

    Ye, Han; Wang, Donglin; Yu, Zhongyuan; Zhang, Jinqiannan; Chen, Zhihui

    2015-04-20

    In this paper, we present extremely compact designs of both broadband mode converter and optical diode in linear rod-type photonic crystal (PhC) waveguide with functional region consisting of only 4 × 1 unit cells of perfect PhC. The dielectric distribution inside functional region are optimized by combining geometry projection method and method of moving asymptotes. Bidirectional mode converter realizes above 60% transmission efficiency within bandwidth 0.02c/a, where c and a represent light velocity and PhC lattice constant respectively. Optical diode achieves above 19 dB unidirectionality for even mode within bandwidth 0.01c/a. Moreover, the proposed designs have reasonable tolerance of rod boundary fluctuation. We expect the results will help developing recipes for future PhC devices in all-optical integrated circuits.

  5. A two-stage photonic crystal fiber / silicon photonic wire short-wave infrared wavelength converter/amplifier based on a 1064 nm pump source.

    PubMed

    Kuyken, B; Leo, F; Mussot, A; Kudlinski, A; Roelkens, G

    2015-05-18

    We demonstrate a two-stage wavelength converter that uses compact near-infrared sources to amplify and convert short-wave infrared signals. The first stage consists of a photonic crystal fiber wavelength converter pumped by a Q-switched 1064 nm pump source, while the second stage consists of a silicon photonic wire waveguide wavelength converter. The system enables on-chip amplification and conversion of up to 30 dB . We demonstrate amplification in a broad wavelength range around 2344 nm using temporally long pulses (>300ps).

  6. Liquid-crystal alignment on polytetrafluoroethylene and high-density polyethylene thin films studied by optical second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Dennis, John R.; Vogel, Viola

    1998-05-01

    We have used optical second-harmonic generation to study surface molecular order in a liquid-crystal (4'-n-octyl-4-cyano-biphenyl, or 8CB) on shear-deposited polymer films. The films are highly oriented layers of polytetrafluoroethylene (PTFE) or high-density polyethylene (HDPE), with a surface topology of uniaxially aligned nanoscale ridges and grooves, which are used as versatile substrates for oriented growth and alignment of other materials. In nematic 8CB cells made with either polymer, the surface monolayers of 8CB were aligned along the polymer orientation axis, and showed C2ν symmetry. In the isotropic phase, the surface monolayer alignment in these cells was lost. Monolayers of 8CB evaporated onto either polymer showed little or no alignment. These data indicate that the PTFE and HDPE films do not produce the strong epitaxylike alignment seen on some cloth-rubbed polymer surfaces. Instead, alignment appears to be primarily caused by surface ridges through an elastic, bulk-mediated mechanism.

  7. Application of the optical second harmonic generation method in the study of the crystallization of noncetrosymmetric phases in glasses

    SciTech Connect

    Stefanovich, S.Yu.; Sigaev, V.N.

    1995-07-01

    The theoretical and experimental foundations of the optical-radiation second harmonic generation (SHG) method are briefly reported. The optimum conditions for applying the SHG method both to an investigation of glasses and glass-ceramics at the early stages of the glass crystallization and to an analysis of the well-formed glass-ceramic structure are determined. The exceptionally high informative capabilities of the SHG method in studies of phase transformations of the {open_quotes}glass-acentric phase{close_quotes} type is demonstrated by the example of glass-forming systems containing the acentric phases [Li{sub 2}SiO{sub 3}, Li{sub 2}GeO{sub 3}, LiB{sub 3}O{sub 5}, Li{sub 2}B{sub 4}O{sub 7}, PbTiO{sub 3}, Pb{sub 5}Ge{sub 3}O{sub 11}, LnBXO{sub 5} (Ln=La, Ce, and Pr; X=Si and Ge), and others].

  8. Technique for locking a second-harmonic generation cavity with an electro-optic active nonlinear crystal

    SciTech Connect

    Cesar, Claudio L.

    2001-08-01

    A new technique for generating an error signal for locking a second-harmonic generation (SHG) enhancement cavity is presented. The calculations are developed within a linear system framework treated with a Laplace transform. The error-signal generation is based on FM sidebands, but it differs from the Pound--Drever--Hall technique by performing the modulation on the (assumed) electro-optic active nonlinear crystal in the cavity. This new technique for generating the error signal has some advantages over the former one in that (i) the shape of the error signal is independent of the relative phase of the rf signal between the photodiode and the local oscillator; (ii) it provides a handy, high-bandwidth actuator to improve the cavity lock, which can improve the average SHG power; and (iii) it decreases cost and complexity by not requiring an external electro-optical modulator. The specific case of SHG in KNbO{sub 3} is treated as an example of the feasibility of the technique. {copyright} 2001 Optical Society of America

  9. The crystal structure, vibrational spectra, thermal behaviour and second harmonic generation of aminoguanidinium(1+) hydrogen L-tartrate monohydrate

    NASA Astrophysics Data System (ADS)

    Macháčková, Zorka; Němec, Ivan; Teubner, Karel; Němec, Petr; Vaněk, Přemysl; Mička, Zdeněk

    2007-04-01

    Aminoguanidinium(1+) hydrogen L-tartrate monohydrate was prepared by crystallisation from aqueous solution and X-ray structural analysis was carried out. The substance crystallises in the orthorhombic system in space group P2 12 12 1, a = 7.1380(2) Å, b = 9.9700(4) Å, c = 14.0790(6) Å, V = 1001.94(7) Å 3, Z = 4, R = 0.0271 for 2272 observed reflections. The crystal structure consists of a 3D framework formed by hydrogen tartrate anions and water molecules with incorporated aminoguanidinium(1+) cations connected by a system of hydrogen bonds. The FTIR and FT Raman spectra of natural and N,O-deuterated compounds were measured and discussed at laboratory temperature. DSC measurements were carried out in the temperature range from 95 to 380 K. A weak anomaly was observed at a temperature of 268 K. Quantitative measurements of second harmonic generation of powdered aminoguanidinium(1+) hydrogen tartrate monohydrate at 800 nm were performed relative to KDP and a relative efficiency of 14% was observed.

  10. Hyperpolarizability Components for α- and ω-Helical Polypeptides in Polar Crystals Determined from Second-Harmonic Generation Measurements

    NASA Astrophysics Data System (ADS)

    Yen, Chu-Chun; Araoka, Fumito; Tokita, Masatoshi; Kawauchi, Susumu; Park, Byoungchoo; Takezoe, Hideo; Watanabe, Junji

    2004-10-01

    Second-harmonic generation (SHG) properties of α-helical and ω-helical polypeptides have been investigated by using crystalline films prepared by casting lyotropic liquid crystal solutions of poly(γ-phenylpropyl L-glutamate) (3PLG) and poly(β-benzyl L-aspartate) (PBLA) under a high electric field. The crystalline films generated SH light upon irradiation of the Nd:YAG laser, which ensures that the films have a polar structure. The in-plane anisotropy of the polarized SH light intensity is well explained by theoretical descriptions under the C6 and C4 symmetries for 3PLG and PBLA, respectively. On the basis of the SHG results, the hyperpolarizability tensor components of the individual polypeptide helical molecules are characterized as βZXX/βZZZ=1.2, βXZX/βZZZ=3.8, and 2βZXX/βXZX=0.7 for the α-helix 3PLG, and βZXX/βZZZ=3.8, βXZX/βZZZ=5.0, and 2βZXX/βXZX=1.5 for the ω-helix PBLA, where the z-axis is set as the helical axis. Quantum chemical calculation is successfully performed to reveal the general character of the polypeptide helix, βZXX>βZZZ.

  11. A new high-resolution crystal structure of the Drosophila melanogaster angiotensin converting enzyme homologue, AnCE.

    PubMed

    Harrison, Charlotte; Acharya, K Ravi

    2015-01-01

    Angiotensin converting enzyme (ACE) is a zinc-dependent dipeptidyl carboxypeptidase with an essential role in blood pressure homeostasis in mammals. ACE has long been targeted in the treatment of hypertension through ACE inhibitors, however current inhibitors are known to cause severe side effects. Therefore, there is a requirement for a new generation of ACE inhibitors and structural information will be invaluable in their development. ACE is a challenging enzyme to work with due to its extensive glycosylation. As such, the Drosophila melanogaster ACE homologue, AnCE, which shares ∼60% sequence similarity with human ACE, can be used as a model for studying inhibitor binding. The presence of ligands originating from the crystallisation condition at the AnCE active site has proved an obstacle to studying the binding of new inhibitor precursors. Here we present the crystal structure of AnCE (in a new crystal form) at 1.85 Å resolution, using crystals grown under different conditions. This new structure may be more suitable for studying the binding of new compounds, with the potential of developing a new generation of improved ACE inhibitors. PMID:26380810

  12. Second Harmonic Generation of Self-Mode-Locked СО2-Laser Radiation in GaSe and GaSeS Crystals

    NASA Astrophysics Data System (ADS)

    Genin, D. E.; Beloplotov, D. V.; Sitnikov, A. G.; Panchenko, A. N.; Sarkisov, S. Yu.; Chernyshov, A. I.

    2014-03-01

    A TEA CO2 laser generating at the wavelength λ = 10.6 μm in the modes of free lasing and self-mode-locking was used to obtain and compare second harmonic generation (SHG) in GaSe and GaSe0.7S0.3 crystals. With the self-mode-locked laser, a 5-times higher energy efficiency of SHG was obtained. The efficiency of SHG in the GaSe0.7S0.3 crystal and its second-order nonlinear susceptibility were estimated and compared with their values for undoped GaSe.

  13. Timing jitter measurement of transmitted laser pulse relative to the reference using type II second harmonic generation in two nonlinear crystals.

    PubMed

    Ma, Xuelian; Liu, Lu; Tang, Junxiong

    2009-10-12

    A new method is proposed and analyzed for measuring the timing jitter of the transmitted pulse relative to the reference pulse using two type II phase-matched nonlinear crystals for second harmonic generation (SHG). The polarizations of the two pulses are exchanged in two crystals and the difference between two detected second harmonic signals can reflect the transmitted jitter. This new method provides a high sensitivity and timing resolution compared with the conventional RF (radio frequency) method. Since the overlapping levels in the two crystals are the same, the final output is zero when there is no time delay between the two pulses. Thus no offset is necessary to be subtracted from the final output and no time delay adjustment is required between the two pulses, compared with the previous optical method using one crystal and two dichroic beamsplitters. The jitter measuring performance is studied theoretically using non-stationary nonlinear wave-coupled equations for type II SHG of two pulses. The theoretical computation and analysis show that the sensitivity and the dynamic range of this new method depend on pulse width, crystal pulses and group velocity difference between two fundamental pulses. PMID:20372647

  14. Second harmonic generation of spectrally broadened femtosecond ytterbium laser radiation in a gas-filled capillary

    SciTech Connect

    Didenko, N V; Konyashchenko, Aleksandr V; Kostryukov, P V; Losev, Leonid L; Tenyakov, S Yu

    2011-09-30

    A 300-fs radiation pulse of an ytterbium laser with a wavelength of 1030 nm and energy of 150 {mu}J were converted to a 15-fs pulse with a wavelength of 515 nm by broadening the emission spectrum in a capillary filled with xenon and by generating the second harmonic in a KDP crystal. The energy efficiency of the conversion was 30 %.

  15. In-situ characterization of femtosecond laser-induced crystallization in borosilicate glass using time-resolved surface third-harmonic generation

    SciTech Connect

    Liu, Weimin; Wang, Liang; Han, Fangyuan; Fang, Chong

    2013-11-11

    Coherent phonon dynamics in condensed-phase medium are responsible for important material properties including thermal and electrical conductivities. We report a structural dynamics technique, time-resolved surface third-harmonic generation (TRSTHG) spectroscopy, to capture transient phonon propagation near the surface of polycrystalline CaF{sub 2} and amorphous borosilicate (BK7) glass. Our approach time-resolves the background-free, high-sensitivity third harmonic generation (THG) signal in between the two crossing near-IR pulses. Pronounced intensity quantum beats reveal the impulsively excited low-frequency Raman mode evolution on the femtosecond to picosecond timescale. After amplified laser irradiation, danburite-crystal-like structure units form at the glass surface. This versatile TRSTHG setup paves the way to mechanistically study and design advanced thermoelectrics and photovoltaics.

  16. In-situ characterization of femtosecond laser-induced crystallization in borosilicate glass using time-resolved surface third-harmonic generation

    NASA Astrophysics Data System (ADS)

    Liu, Weimin; Wang, Liang; Han, Fangyuan; Fang, Chong

    2013-11-01

    Coherent phonon dynamics in condensed-phase medium are responsible for important material properties including thermal and electrical conductivities. We report a structural dynamics technique, time-resolved surface third-harmonic generation (TRSTHG) spectroscopy, to capture transient phonon propagation near the surface of polycrystalline CaF2 and amorphous borosilicate (BK7) glass. Our approach time-resolves the background-free, high-sensitivity third harmonic generation (THG) signal in between the two crossing near-IR pulses. Pronounced intensity quantum beats reveal the impulsively excited low-frequency Raman mode evolution on the femtosecond to picosecond timescale. After amplified laser irradiation, danburite-crystal-like structure units form at the glass surface. This versatile TRSTHG setup paves the way to mechanistically study and design advanced thermoelectrics and photovoltaics.

  17. Quaternionic Harmonic Analysis of Texture

    SciTech Connect

    Mason, J.

    2012-10-01

    QHAT uses various functions and data structures native to MATLAB to analyze crystallographic texture information using harmonic functions on the space of rotations represented as normalized quaternions. These harmonic functions generalize the spherical harmonics in three dimensions, and form the basis for the irreducible representations of the four-dimensional rotation group. This allows the basis of harmonic functions to be reduced to linearly independent combinations that satisfy the crystal and sample symmetry point groups.

  18. On how differently the quasi-harmonic approximation works for two isostructural crystals: Thermal properties of periclase and lime

    SciTech Connect

    Erba, A. Dovesi, R.; Shahrokhi, M.; Moradian, R.

    2015-01-28

    Harmonic and quasi-harmonic thermal properties of two isostructural simple oxides (periclase, MgO, and lime, CaO) are computed with ab initio periodic simulations based on the density-functional-theory (DFT). The more polarizable character of calcium with respect to magnesium cations is found to dramatically affect the validity domain of the quasi-harmonic approximation that, for thermal structural properties (such as temperature dependence of volume, V(T), bulk modulus, K(T), and thermal expansion coefficient, α(T)), reduces from [0 K-1000 K] for MgO to just [0 K-100 K] for CaO. On the contrary, thermodynamic properties (such as entropy, S(T), and constant-volume specific heat, C{sub V}(T)) are described reliably at least up to 2000 K and quasi-harmonic constant-pressure specific heat, C{sub P}(T), up to about 1000 K in both cases. The effect of the adopted approximation to the exchange-correlation functional of the DFT is here explicitly investigated by considering five different expressions of three different classes (local-density approximation, generalized-gradient approximation, and hybrids). Computed harmonic thermodynamic properties are found to be almost independent of the adopted functional, whereas quasi-harmonic structural properties are more affected by the choice of the functional, with differences that increase as the system becomes softer.

  19. Broadband 120 MHz Impedance Quartz Crystal Microbalance (QCM) with Calibrated Resistance and Quantitative Dissipation for Biosensing Measurements at Higher Harmonic Frequencies

    PubMed Central

    Kasper, Manuel; Traxler, Lukas; Salopek, Jasmina; Grabmayr, Herwig; Ebner, Andreas; Kienberger, Ferry

    2016-01-01

    We developed an impedance quartz crystal microbalance (QCM) approach with the ability to simultaneously record mass changes and calibrated energy dissipation with high sensitivity using an impedance analyzer. This impedance QCM measures frequency shifts and resistance changes of sensing quartz crystals very stable, accurately, and calibrated, thus yielding quantitative information on mass changes and dissipation. Resistance changes below 0.3 Ω were measured with corresponding dissipation values of 0.01 µU (micro dissipation units). The broadband impedance capabilities allow measurements between 20 Hz and 120 MHz including higher harmonic modes of up to 11th order for a 10 MHz fundamental resonance frequency quartz crystal. We demonstrate the adsorbed mass, calibrated resistance, and quantitative dissipation measurements on two biological systems including the high affinity based avidin-biotin interaction and nano-assemblies of polyelectrolyte layers. The binding affinity of a protein-antibody interaction was determined. The impedance QCM is a versatile and simple method for accurate and calibrated resistance and dissipation measurements with broadband measurement capabilities for higher harmonics measurements. PMID:27231946

  20. Broadband 120 MHz Impedance Quartz Crystal Microbalance (QCM) with Calibrated Resistance and Quantitative Dissipation for Biosensing Measurements at Higher Harmonic Frequencies.

    PubMed

    Kasper, Manuel; Traxler, Lukas; Salopek, Jasmina; Grabmayr, Herwig; Ebner, Andreas; Kienberger, Ferry

    2016-05-25

    We developed an impedance quartz crystal microbalance (QCM) approach with the ability to simultaneously record mass changes and calibrated energy dissipation with high sensitivity using an impedance analyzer. This impedance QCM measures frequency shifts and resistance changes of sensing quartz crystals very stable, accurately, and calibrated, thus yielding quantitative information on mass changes and dissipation. Resistance changes below 0.3 Ω were measured with corresponding dissipation values of 0.01 µU (micro dissipation units). The broadband impedance capabilities allow measurements between 20 Hz and 120 MHz including higher harmonic modes of up to 11th order for a 10 MHz fundamental resonance frequency quartz crystal. We demonstrate the adsorbed mass, calibrated resistance, and quantitative dissipation measurements on two biological systems including the high affinity based avidin-biotin interaction and nano-assemblies of polyelectrolyte layers. The binding affinity of a protein-antibody interaction was determined. The impedance QCM is a versatile and simple method for accurate and calibrated resistance and dissipation measurements with broadband measurement capabilities for higher harmonics measurements.

  1. Broadband 120 MHz Impedance Quartz Crystal Microbalance (QCM) with Calibrated Resistance and Quantitative Dissipation for Biosensing Measurements at Higher Harmonic Frequencies.

    PubMed

    Kasper, Manuel; Traxler, Lukas; Salopek, Jasmina; Grabmayr, Herwig; Ebner, Andreas; Kienberger, Ferry

    2016-01-01

    We developed an impedance quartz crystal microbalance (QCM) approach with the ability to simultaneously record mass changes and calibrated energy dissipation with high sensitivity using an impedance analyzer. This impedance QCM measures frequency shifts and resistance changes of sensing quartz crystals very stable, accurately, and calibrated, thus yielding quantitative information on mass changes and dissipation. Resistance changes below 0.3 Ω were measured with corresponding dissipation values of 0.01 µU (micro dissipation units). The broadband impedance capabilities allow measurements between 20 Hz and 120 MHz including higher harmonic modes of up to 11th order for a 10 MHz fundamental resonance frequency quartz crystal. We demonstrate the adsorbed mass, calibrated resistance, and quantitative dissipation measurements on two biological systems including the high affinity based avidin-biotin interaction and nano-assemblies of polyelectrolyte layers. The binding affinity of a protein-antibody interaction was determined. The impedance QCM is a versatile and simple method for accurate and calibrated resistance and dissipation measurements with broadband measurement capabilities for higher harmonics measurements. PMID:27231946

  2. Production, purification, and crystallization of human interleukin-1 beta converting enzyme derived from an Escherichia coli expression system.

    PubMed Central

    Malinowski, J. J.; Grasberger, B. L.; Trakshel, G.; Huston, E. E.; Helaszek, C. T.; Smallwood, A. M.; Ator, M. A.; Banks, T. M.; Brake, P. G.; Ciccarelli, R. B.

    1995-01-01

    Interleukin-1 beta converting enzyme (ICE) is a cysteine protease that catalyzes the conversion of the inactive precursor form of IL-1 beta to an active mature form. The mature form of IL-1 beta is involved in mediating inflammatory responses and in the progression of autoimmune diseases. We recently reported on the production of active human ICE in insect cells using the baculovirus expression system (Wang XM et al., 1994, Gene 145:273-277). Because the levels of expression achieved with this system were limiting for the purpose of performing detailed biochemical and biophysical studies, we examined the production of ICE in Escherichia coli. By using a tac promoter-based expression system and fusion to thioredoxin we were able to recover high levels of active ICE protein. The expressed protein, which was distributed between the soluble and insoluble fractions, was purified to homogeneity from both fractions using a combination of classical and affinity chromatography. Comparisons of ICE derived from both fractions indicated that they were comparable in their specific activities, subunit composition, and sensitivities to specific ICE inhibitors. The combined yields of ICE obtained from the soluble and insoluble fractions was close to 1 mg/L of induced culture. Recombinant human ICE was crystallized in the presence of a specific ICE inhibitor in a form suitable for X-ray crystallographic analysis. This readily available source of ICE will facilitate the further characterization of this novel and important protease. PMID:8535252

  3. Investigation of organic nonlinear optical crystals for harmonic frequency conversion and electro-optics. Final technical report

    SciTech Connect

    1998-01-01

    The authors are conducting a detailed study of the crystal growth of different organic materials and their physical, optical and morphological properties. The crystals are grown by a novel solution crystal growth technique developed by the principal investigator at Alabama A and M University (AAMU). The studies included the measurement of solubility of organic NLO materials in different solvents, growth of crystals by solution growth technique, and the characterization of optical properties and damage threshold of crystals for high power laser applications. Two different NLO crystals of 4-Aminobenzophenone (ABP) and 3-methoxy-4-hydroxy-benzaldehyde (MHBA) were investigated during the course of this investigation. A paper on ABP crystals was published in Journal of Crystal Growth in 1997.

  4. Optical harmonic generator

    DOEpatents

    Summers, Mark A.; Eimerl, David; Boyd, Robert D.

    1985-01-01

    A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The "extraordinary" or "e" directions of the crystal elements are oriented in the integral assembly to be in quadrature (90.degree.). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude "o" and "e" components. For a third-harmonic generation, the input fundamental wave has "o" and "e" components whose amplitudes are in a ratio of 2:1 ("o":"e" reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10.degree.. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axes ("o").

  5. Optical harmonic generator

    DOEpatents

    Summers, M.A.; Eimerl, D.; Boyd, R.D.

    1982-06-10

    A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The extraordinary or e directions of the crystal elements are oriented in the integral assembly to be in quadrature (90/sup 0/). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude o and e components. For a third-harmonic generation, the input fundamental wave has o and e components whose amplitudes are in a ratio of 2:1 (o:e reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10/sup 0/. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axeses (o).

  6. The use of ( R)-(+)-α-methylbenzylamine and ( S)-(-)-α-methylbenzylamine as chiral moieties to obtain monomers for second harmonic generation crystals

    NASA Astrophysics Data System (ADS)

    Chapela, V. M.; Percino, M. J.; Jiménez, A.; Ortega-Martínez, R.; Escalante, C. A.; Rodríguez de Barbarín, C.

    2003-03-01

    The use of chiral moieties as a way to warranty noncentrosymmetric monomers crystals in order to obtain second harmonic generation materials has been the study purpose of nonlinear properties of the two new N-( R)-(+)-α- and N-( S)-(-)-α-methylbenzylmethacryloylamine enantiomeric monomers. The enantiomeric monomers crystallized in a monoclinic system and belong to the P2 1 space group and the asymmetric unit comprises two molecules of the enantiomeric compound. The molecular structure shows that the amide moiety is not coplanar with the double bond of the methylene group, as one would assume before hand. The hydrogen bond system is formed between the symmetry related molecules using H atom of the amide and keto oxygen of consecutive molecules along the a axis forming parallel series of continuous chains The second-harmonic generation produced 532 nm light for both compounds and they were measured following the Kurtz and Perry modified procedure in powder form. The values were compared with the chiral compound (saccharose, sucrose, know as sugar) calibration spectrum used as standard. The monomers characterization were made using conventional methods: melting point measurements, infrared spectroscopy, nuclear magnetic resonance spectroscopy and polarimetry.

  7. Growth and characterization of crystals for room temperature I.R. detectors and second harmonic generation devices

    NASA Technical Reports Server (NTRS)

    Lal, R. B.

    1995-01-01

    One of the major objectives of this program was to modify the triglycine sulfate (TGS) crystals with suitable dopants and variants to achieve better pyroelectric properties and improved infrared detectivities (D(sup *)), and higher Curie transition temperature compared to undoped TGS crystals. Towards these objectives, many promising dopants, both inorganic and organic, were investigated in the last few years. These dopants gave significant improvement in the D(sup *) value of the infrared detectors fabricated from the grown crystals with no significant increase in the Curie temperature (49 C). The IR detectors were fabricated at EDO/Barnes Engineering Division, Shelton, CT. In the last one year many TGS crystals doped with urea were grown using the low temperature solution crystal growth facility. It is found that doping with urea, the normalized growth yield increased significantly compared to pure TGS crystals and there is an improvement in the pyroelectric and dielectric constant values of doped crystals. This gave a significant increase in the materials figure of merits. The Vicker's hardness of 10 wt percent urea doped crystals is found to be about three times higher in the (010) direction compared to undoped crystals. This report describes in detail the results of urea doped TGS crystals.

  8. Remarkable enhancement in crystalline perfection, second harmonic generation efficiency, optical transparency, and laser damage threshold in potassium dihydrogen phosphate crystals by L-threonine doping

    SciTech Connect

    Kushwaha, S. K.; Maurya, K. K.; Bhagavannarayana, G.; Shakir, Mohd.; Shah, A. L.; Wahab, M. A.

    2010-08-15

    Effect of L-threonine (LT) doping on crystalline perfection, second harmonic generation (SHG) efficiency, optical transparency, and laser damage threshold (LDT) in potassium dihydrogen phosphate (KDP) crystals grown by slow evaporation solution technique (SEST) has been investigated. The influence of doping on growth rate and morphology of the grown crystals has also been studied. Powder x-ray diffraction data confirms the crystal structure of KDP and shows a systematic variation in intensity of diffraction peaks in correlation with morphology due to varying LT concentration. No extra phase formation was observed which is further confirmed by Fourier transform Raman (FT-Raman) studies. High-resolution x-ray diffraction curves indicate that crystalline perfection has been improved to a great extent at low concentrations with a maximum perfection at 1 mol % doping. At higher concentrations (5 to 10 mol %), it is slightly reduced due to excess incorporation of dopants at the interstitial sites of the crystalline matrix. LDT has been increased considerably with increase in doping concentration, whereas SHG efficiency was found to be maximum at 1 mol % in correlation with crystalline. The optical transparency for doped crystals has been increased as compared to that of pure KDP with a maximum value at 1 mol % doping.

  9. Micromachining of liquid crystal polymer film with frequency converted diode-pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Li, Mingwei; Hix, Ken; Dosser, Larry R.; Hartke, Kevin; Blackshire, Jim

    2003-07-01

    Liquid crystal polymer (LCP) is a new and innovative material being used as an alternative to polyimide in the flexible circuit industry. LCP has many intrinsic benefits over polyimide including lower moisture absorption and improved dimensional stability. However, LCP is very resistant to chemical milling or etching. As a result, other methods for processing the material are being investigated including laser micromachining. In this paper, three frequency converted diode-pumped solid-state (DPSS) Nd:YVO4 lasers at 355 nm were used to micromachine a LCP film and a copper/LCP laminate. Of them, two are Q-switched lasers operating in the nanosecond regime and the other a mode-locked laser in the picosecond regime. The Q-switched lasers can be operated at pulse repetition rates of 1 to 300 kHz while the mode-locked system is operated at 80 MHz. The micromachining experiments consisted of cutting the 50 μm thick LCP film, cutting the 18 μm thick copper on the film, and drilling micro-vias through both the copper coating and the film substrate. The laser/material interactions and processing speeds were studied and compared. The results show that, compared to polyimide film of the same thickness, LCP film can be more efficiently processed by laser micromachining. In addition, each laser has a unique advantage in processing LCP based flexible circuit materials. The Q-switched lasers are more capable of processing the copper coating while the mode-locked laser can cut LCP film faster with the smallest kerf width.

  10. Phase-matched electric-field-induced second-harmonic generation in Xe-filled hollow-core photonic crystal fiber.

    PubMed

    Ménard, Jean-Michel; Russell, Philip St J

    2015-08-01

    Second-order nonlinearity is induced inside a Xe-filled hollow-core photonic crystal fiber (PCF) by applying an external dc field. The system uniquely allows the linear optical properties to be adjusted by changing the gas pressure, allowing for precise phase matching between the LP01 mode at 1064 nm and the LP02 mode at 532 nm. The dependence of the second-harmonic conversion efficiency on the gas pressure, launched pulse energy, and applied field agrees well with theory. The ultra-broadband guidance offered by anti-resonant reflecting hollow-core PCFs, for example, a kagomé PCF, offers many possibilities for generating light in traditionally difficult-to-access regions of the electromagnetic spectrum, such as the ultraviolet or the terahertz windows. The system can also be used for noninvasive measurements of the transmission loss in a hollow-core PCF over a broad spectrum, including the deep and vacuum UV regions.

  11. Fast ion energy distribution from third harmonic radio frequency heating measured with a single crystal diamond detector at the Joint European Torus

    SciTech Connect

    Nocente, M.; Rebai, M.; Gorini, G.; Cazzaniga, C.; Tardocchi, M.; Giacomelli, L.; Muraro, A.; Binda, F.; Eriksson, J.; Sharapov, S.; Collaboration:

    2015-10-15

    Neutron spectroscopy measurements with a single crystal diamond detector have been carried out at JET, for the first time in an experiment aimed at accelerating deuterons to MeV energies with radio frequency heating at the third harmonic. Data are interpreted by means of the expected response function of the detector and are used to extract parameters of the highly non-Maxwellian distribution function generated in this scenario. A comparison with observations using a time of flight and liquid scintillator neutron spectrometers is also presented. The results demonstrate the capability of diamond detectors to contribute to fast ion physics studies at JET and are of more general relevance in view of the application of such detectors for spectroscopy measurements in the neutron camera of next step tokamak devices.

  12. The effect of air flow on the temperature distribution and the harmonic conversion efficiency of the ADP crystal with large aperture in the temperature control scheme

    NASA Astrophysics Data System (ADS)

    Sun, Fuzhong; Zhang, Peng; Lu, Lihua; Xiang, Yong; Bai, Qingshun

    2016-03-01

    This paper presented a temperature control scheme for ammonium dihydrogen phosphate (ADP) crystal of V80 mm in diameter, and the influence of the air flow was also studied. This research aims to obtain the high energy, high frequency laser with large aperture under the non-critical phase matching (NCPM). Firstly, thermal analysis was carried out to investigate the air flow property in the cavity, as well as the effect of ambient temperature was analyzed. Secondly, the temperature distributions of air flow were achieved using the Finite Volume Method (FVM), and this prediction was validated by the experiment results. Finally, the effect of air flow in the cavity was obtained from the heating method, and the variation of harmonic conversion efficiency caused by the ambient temperature was also highlighted.

  13. Investigation about relationships between the symmetries of ferroelectric crystal Ca{sub 0.28}Ba{sub 0.72}Nb{sub 2}O{sub 6} and second-harmonic patterns

    SciTech Connect

    Xu, Tianxiang; Yu, Haohai Zhang, Huaijin Wang, Jiyang

    2015-08-07

    The broadband quasi-phase matching (QPM) process in a uniaxial ferroelectric crystal Ca{sub 0.28}Ba{sub 0.72}Nb{sub 2}O{sub 6} (CBN-28) was demonstrated with the second-harmonic wavelength range from 450 nm to 650 nm, and the relationship between the symmetries of CBN-28 and the second-harmonic patterns was experimentally and theoretically investigated based on the random anti-parallel domains in the crystal and QPM conditions. The dependences of frequency-doubled patterns on the wavelength and anisotropy of the nonlinear crystal were also studied, and the frequency-doubled photons were found to be trapped on circles. By analyzing the light-matter interacting Hamiltonians, the trapping force for second-harmonic photons was found to be centripetal and tunable by the fundamental lasers, and the variation tendencies of the rotational velocity of second-harmonic generation photons could also be predicated. The results indicate that the CBN-28 ferroelectric crystal is a promising nonlinear optical material for the generation of broadband frequency-doubled waves, and the analysis on centripetal force based on the interaction Hamiltonians may provide a novel recognition for the investigation of QPM process to be further studied.

  14. First-principles study of crystal structure, electronic structure, and second-harmonic generation in a polar double perovskite Bi2ZnTiO6.

    PubMed

    Ju, Sheng; Guo, Guang-Yu

    2008-11-21

    Within the density functional theory with the generalized gradient approximation, we present a systematic ab initio investigation of crystal structure, electronic structure, and linear and nonlinear optical responses in a polar double perovskite Bi(2)ZnTiO(6). The effect of B-site ordering is explored by comparing three possible configurations: A-type with alternative Zn and Ti layers stacking along the c axis; C-type with Zn and Ti c axis chains; and G-type with every Zn(Ti) atoms is surrounded by its nearby six Ti(Zn) atoms. It is found that the system with G-type B-site ordering is energetically favorable, which is lower in the total energies of 0.055 and 0.133 eV/formula unit than C-type and A-type, respectively. Optical calculations indicate that all the three configurations show large second-harmonic generation (SHG) coefficients, and the largest static SHG observed in the C-type system reaches 123 (10(-9) esu), the value of which is much larger than ever known polar oxides, e.g., 72 (10(-9) esu) in LiNbO(3). The predicted significant nonlinear optical properties are consistent with the calculated high tetragonality as well as the large off-center displacement of Zn, Ti, and Bi atoms. In particular, a large off-center displacement greater than 0.5 A in Zn atoms is revealed for the first time. A further microscopic picture is presented via the successful connection of the prominent feature of SHG in Bi(2)ZnTiO(6) with that of the linear optical dielectric function in terms of single-photon and double-photon resonances. Our calculations demonstrate the promising application of Bi(2)ZnTiO(6) in optoelectronics.

  15. Modeling of large aperture third harmonic frequency conversion of high power Nd:glass laser systems

    SciTech Connect

    Henesian, M.A.; Wegner, P.J.; Speck, D.R.; Bibeau, C.; Ehrlich, R.B.; Laumann, C.W.; Lawson, J.K.; Weiland, T.L.

    1991-03-13

    To provide high-energy, high-power beams at short wavelengths for inertial-confinement-fusion experiments, we routinely convert the 1.053-{mu}m output of the Nova, Nd:phosphate-glass, laser system to its third-harmonic wavelength. We describe performance and conversion efficiency modeling of the 3 {times} 3 arrays potassium-dihydrogen-phosphate crystal plates used for type II/type II phase-matched harmonic conversion of Nova 0.74-m diameter beams, and an alternate type I/type II phase-matching configuration that improves the third-harmonic conversion efficiency. These arrays provide energy conversion of up to 65% and intensity conversion to 70%. 19 refs., 11 figs.

  16. In-phased second harmonic wave array generation with intra-Talbot-cavity frequency-doubling.

    PubMed

    Hirosawa, Kenichi; Shohda, Fumio; Yanagisawa, Takayuki; Kannari, Fumihiko

    2015-03-23

    The Talbot cavity is one promising method to synchronize the phase of a laser array. However, it does not achieve the lowest array mode with the same phase but the highest array mode with the anti-phase between every two adjacent lasers, which is called out-phase locking. Consequently, their far-field images exhibit 2-peak profiles. We propose intra-Talbot-cavity frequency-doubling. By placing a nonlinear crystal in a Talbot cavity, the Talbot cavity generates an out-phased fundamental wave array, which is converted into an in-phase-locked second harmonic wave array at the nonlinear crystal. We demonstrate numerical calculations and experiments on intra-Talbot-cavity frequency-doubling and obtain an in-phase-locked second harmonic wave array for a Nd:YVO₄ array laser.

  17. Frequency converter development for the National Ignition Facility

    SciTech Connect

    Auerbach, J M; Barker, C E; Burkhart, S C; Couture, S A; DeYoreo, J J; Hackel, L A; Hibbard, R L; Liou, L W; Norton, M A; Wegner, P J; Whitman, P A

    1998-10-30

    The design of the National Ignition Facility (NIF) incorporates a type I/type II third harmonic generator to convert the 1.053-{micro}m fundamental wavelength of the laser amplifier to a wavelength of 0.351 {micro}m for target irradiation. To understand and control the tolerances in the converter design, we have developed a comprehensive error budget that accounts for effects that are known to influence conversion efficiency, including variations in amplitude and phase of the incident laser pulse, temporal bandwidth of the incident laser pulse, crystal surface figure and bulk non-uniformities, angular alignment errors, Fresnel losses, polarization errors and crystal temperature variations. The error budget provides specifications for the detailed design of the NIF final optics assembly (FOA) and the fabrication of optical components. Validation is accomplished through both modeling and measurement, including full-scale Beamlet tests of a 37-cm aperture frequency converter in a NIF prototype final optics cell. The prototype cell incorporates full-perimeter clamping to support the crystals, and resides in a vacuum environment as per the NIF design.

  18. Organometallic Salts Generate Optical Second Harmonics

    NASA Technical Reports Server (NTRS)

    Marder, Seth R.; Perry, Joseph W.

    1991-01-01

    Series of organometallic salts exhibit large second-order dielectric susceptibilities, as evidenced by generation of second harmonics when illuminated at visible and near-infrared wavelengths. Investigations of these and related compounds continue with view toward development of materials for use as optical second-harmonic generators, electro-optical modulators, optical switches, piezoelectric sensors, and parametric crystals.

  19. Harmonic engine

    DOEpatents

    Bennett, Charles L.

    2009-10-20

    A high efficiency harmonic engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes harmonic oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.

  20. Successive approximation-like 4-bit full-optical analog-to-digital converter based on Kerr-like nonlinear photonic crystal ring resonators

    NASA Astrophysics Data System (ADS)

    Tavousi, Alireza; Mansouri-Birjandi, Mohammad Ali; Saffari, Mehdi

    2016-09-01

    Implementing of photonic sampling and quantizing analog-to-digital converters (ADCs) enable us to extract a single binary word from optical signals without need for extra electronic assisting parts. This would enormously increase the sampling and quantizing time as well as decreasing the consumed power. To this end, based on the concept of successive approximation method, a 4-bit full-optical ADC that operates using the intensity-dependent Kerr-like nonlinearity in a two dimensional photonic crystal (2DPhC) platform is proposed. The Silicon (Si) nanocrystal is chosen because of the suitable nonlinear material characteristic. An optical limiter is used for the clamping and quantization of each successive levels that represent the ADC bits. In the proposal, an energy efficient optical ADC circuit is implemented by controlling the system parameters such as ring-to-waveguide coupling coefficients, the ring's nonlinear refractive index, and the ring's length. The performance of the ADC structure is verified by the simulation using finite difference time domain (FDTD) method.

  1. Harmonic engine

    SciTech Connect

    Bennett, Charles L.; Sewall, Noel; Boroa, Carl

    2014-08-19

    An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into of the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. Upon releasing the inlet valve the inlet valve head undergoes a single oscillation past the equilibrium positio to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. Protrusions carried either by the inlet valve head or piston head are used to bump open the inlet valve from the closed position and initiate the single oscillation of the inlet valve head, and protrusions carried either by the outlet valve head or piston head are used to close the outlet valve ahead of the bump opening of the inlet valve.

  2. CAVE: the design of a precision metrology instrument for studying performance of KDP crystals

    SciTech Connect

    Hibbard, R.L., LLNL

    1998-03-30

    A device has been developed to measure the frequency conversion performance of large aperture potassium dihydrogen phosphate (KDP) crystals. Third harmonic generation using ICDP is critical to the function of the National Ignition Facility (NIF) laser. The crystals in the converter can be angularly or thermally tuned but are subject to larger aperture inhomogeneities that are functions of growth manufacturing and - mounting. The CAVE (Crystal Alignment Verification Equipment) instrument scans the crystals in a thermally and mechanically controlled environment to determine the local peak tuning angles. The CAVE can then estimate the optimum tuning angle and conversion efficiency over the entire aperture. Coupled with other metrology techniques, the CAVE will help determine which crystal life-cycle components most affect harmonic conversion.

  3. Thermionic converter

    DOEpatents

    Fitzpatrick, G.O.

    1987-05-19

    A thermionic converter is set forth which includes an envelope having an electron collector structure attached adjacent to a wall. An electron emitter structure is positioned adjacent the collector structure and spaced apart from opposite wall. The emitter and collector structures are in a common chamber. The emitter structure is heated substantially only by thermal radiation. Very small interelectrode gaps can be maintained utilizing the thermionic converter whereby increased efficiency results. 10 figs.

  4. Ac-dc converter firing error detection

    SciTech Connect

    Gould, O.L.

    1996-07-15

    Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal.

  5. Watt-level second-harmonic generation at 589  nm with a PPMgO:LN ridge waveguide crystal pumped by a DBR tapered diode laser.

    PubMed

    Bege, R; Jedrzejczyk, D; Blume, G; Hofmann, J; Feise, D; Paschke, K; Tränkle, G

    2016-04-01

    A DBR tapered diode laser in continuous wave operation was used to generate second-harmonic radiation at 589 nm in a PPMgO:LN ridge waveguide crystal. An optical output power of 0.86 W at an optical-to-optical and an electrical-to-optical efficiency of 42% and 11%, respectively, was achieved. The visible radiation was characterized by a spectral bandwidth ΔνFWHM of 230 MHz and a beam propagation parameter M1/e22 better than 1.1. The integration of such a system into a housing of a small footprint will enable a portable and highly efficient module featuring a visible output power in the watt-level range. PMID:27192279

  6. Thermionic converter

    DOEpatents

    Fitzpatrick, Gary O.

    1987-05-19

    A thermionic converter (10) is set forth which includes an envelope (12) having an electron collector structure (22) attached adjacent to a wall (16). An electron emitter structure (24) is positioned adjacent the collector structure (22) and spaced apart from opposite wall (14). The emitter (24) and collector (22) structures are in a common chamber (20). The emitter structure (24) is heated substantially only by thermal radiation. Very small interelectrode gaps (28) can be maintained utilizing the thermionic converter (10) whereby increased efficiency results.

  7. The third harmonic in the Russia-Finland DC interconnection

    SciTech Connect

    Kazachkov, Yu. ); Boyarsky, A.; Kraichik, Yu. )

    1994-10-01

    During 12 years of operation of the DC back-to-back tie between Russia and Finland some undesirable phenomena at frequencies close to the third harmonic have been noticed. They may become more severe after the planned upgrading of the converter station. Steady state and transient processes with dominant third harmonic and their improvement by means of filters in the power and control circuits have been studied. Recordings of steady states with noticeable third harmonic are included.

  8. Frequency mixing crystal

    DOEpatents

    Ebbers, Christopher A.; Davis, Laura E.; Webb, Mark

    1992-01-01

    In a laser system for converting infrared laser light waves to visible light comprising a source of infrared laser light waves and means of harmoic generation associated therewith for production of light waves at integral multiples of the frequency of the original wave, the improvement of said means of harmonic generation comprising a crystal having the chemical formula X.sub.2 Y(NO.sub.3).sub.5 .multidot.2 nZ.sub.2 o wherein X is selected from the group consisting of Li, Na, K, Rb, Cs, and Tl; Y is selected from the group consisting of Sc, Y, La, Ce, Nd, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In; Z is selected from the group consisting of H and D; and n ranges from 0 to 4.

  9. Harmonic polynomials, hyperspherical harmonics, and atomic spectra

    NASA Astrophysics Data System (ADS)

    Avery, John Scales

    2010-01-01

    The properties of monomials, homogeneous polynomials and harmonic polynomials in d-dimensional spaces are discussed. The properties are shown to lead to formulas for the canonical decomposition of homogeneous polynomials and formulas for harmonic projection. Many important properties of spherical harmonics, Gegenbauer polynomials and hyperspherical harmonics follow from these formulas. Harmonic projection also provides alternative ways of treating angular momentum and generalised angular momentum. Several powerful theorems for angular integration and hyperangular integration can be derived in this way. These purely mathematical considerations have important physical applications because hyperspherical harmonics are related to Coulomb Sturmians through the Fock projection, and because both Sturmians and generalised Sturmians have shown themselves to be extremely useful in the quantum theory of atoms and molecules.

  10. Harmonic and Anharmonic Properties of Diamond Structure Crystals with Application to the Calculation of the Thermal Expansion of Silicon. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Wanser, K. H.

    1981-01-01

    Silicon has interesting harmonic and anharmonic properties such as the low lying transverse acoustic modes at the X and L points of the Brillouin zone, negative Gruneisen parameters, negative thermal expansion and anomalous acoustic attenuation. In an attempt to understand these properties, a lattice dynamical model employing long range, nonlocal, dipole-dipole interactions was developed. Analytic expression for the Gruneisen parameters of several modes are presented. These expressions explain how the negative Gruneisen parameters arise. This model is applied to the calculation of the thermal expansion of silicon from 5K to 1700K. The thermoelastic contribution to the acoustic attenuation of silicon is computed from 1 to 300 K. Strong attenuation anomalies associated with negative thermal expansion are found in the vicinity of 17K and 125K.

  11. High harmonics from solids probe Angstrom scale structure

    NASA Astrophysics Data System (ADS)

    You, Yong Sing; Reis, David; Ghimire, Shambhu

    2016-05-01

    The basic microscopic mechanism for the high harmonics generation (HHG) in isolated atoms and molecules has been understood in the 90's. Since then the gas harmonics have been utilized widely in ultrafast x-ray science, from attosecond pulse generation to imaging molecular orbitals of the target molecule. In contrast, the solid-state harmonic generation mechanism is currently being investigated following the recent experimental discovery in zinc oxide crystal. In particular, because of the fundamental differences, attributed to the high density and periodicity of the crystal, it was not clear if the solid-state harmonics could be used to reveal bonding structures in crystals. Here we report our experimental results on generation of XUV harmonics in single crystal MgO subjected to the field strengths on the order of 1V/Å without damage. High harmonics in MgO show strong crystal orientation dependence as well as a strong laser ellipticity dependence. By exploiting these unique characteristics, we demonstrate that XUV harmonics from bulk crystals can probe Angstrom scale electronic structure of the crystal.

  12. Assessment on third order non linearity and other optical analyses of L-Asparagine Monohydrate single crystal: An efficient candidate for harmonic conversions.

    PubMed

    Thukral, Kanika; Vijayan, N; Haranath, D; Jayaramakrishnan, V; Philip, J; Sreekanth, P; Bhagavannaryana, G

    2015-12-01

    Single crystal of l-Asparagine Monohydrate, an organic material has been successfully grown by slow evaporation solution growth technique at ambient condition. The lattice parameters and its strain of the grown crystal have been evaluated from powder X-ray diffraction and found that it belongs to orthorhombic crystal system. The polarizability has been measured by using the Clausius-Mossotti relation. The crystalline perfection of grown single crystal has been examined by high resolution X-ray diffraction and its imperfection in the diffraction plane was clearly visible by recording topographical image of the plane. From the high resolution XRD, it confirms that the crystal contained high crystalline perfection. The optical behavior was analyzed by photoluminescence and birefringence methods. In the photoluminescence, a broad peak has been observed at 475 nm which suggest that it emits blue light. The decay tendency of the material has also been observed by calculating decay constant. The optical homogeneity has been determined by the dispersion pattern of the material. The two photon absorption coefficient was further calculated by Z-scan, which gives the information about the third order non linear optical behavior of the material. The value of two-photon absorption coefficient is 4.25 × 10(-12)m/W. The thermal parameters like thermal effusivity, thermal diffusivity, specific heat and thermal conductivity was obtained by using photopyroelectric technique. The ferroelectric behavior of the grown specimen was analyzed from PE (polarization VS electric field) loop. The loop suggests that the material was a nearly equivalent to ideal capacitor. PMID:26148830

  13. Color harmonization for images

    NASA Astrophysics Data System (ADS)

    Tang, Zhen; Miao, Zhenjiang; Wan, Yanli; Wang, Zhifei

    2011-04-01

    Color harmonization is an artistic technique to adjust a set of colors in order to enhance their visual harmony so that they are aesthetically pleasing in terms of human visual perception. We present a new color harmonization method that treats the harmonization as a function optimization. For a given image, we derive a cost function based on the observation that pixels in a small window that have similar unharmonic hues should be harmonized with similar harmonic hues. By minimizing the cost function, we get a harmonized image in which the spatial coherence is preserved. A new matching function is proposed to select the best matching harmonic schemes, and a new component-based preharmonization strategy is proposed to preserve the hue distribution of the harmonized images. Our approach overcomes several shortcomings of the existing color harmonization methods. We test our algorithm with a variety of images to demonstrate the effectiveness of our approach.

  14. Multipurpose Power Converter for Non-Grid-Connected Microsystems

    NASA Astrophysics Data System (ADS)

    Vovos, Panagis N.; Georgakas, Konstantinos G.

    2015-04-01

    The aim of this paper is to present a multipurpose converter, appropriate for non-grid-connected microsystems, which are prone to harmonic distortion. The converter suppresses harmonics by injecting mirror harmonics in the modulation stage. An important property is that it continuously monitors and significantly reduces the harmonic content without the use of active or passive low-frequency filters. This is under constant switching frequency, no matter if the harmonics are mainly created by the source, the loads or even its own operation. The converter is regulating output voltage using typical fuzzy control. The two types of control (harmonic and voltage) do not seem to affect each other during operation. Furthermore, it can supply either dc or ac loads from a dc source. The versatility of the converter is a useful property for remote or mobile micropower systems, where neither sources nor loads are of a single type. The converter has been tested successfully for a combination of harmonic-injecting electric appliances and various load step changes.

  15. Simple Harmonic Motion in Harmonic Plane Waves.

    ERIC Educational Resources Information Center

    Benumof, Reuben

    1980-01-01

    Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

  16. Spectrum of second-harmonic radiation generated from incoherent light

    SciTech Connect

    Stabinis, A.; Pyragaite, V.; Tamosauskas, G.; Piskarskas, A.

    2011-10-15

    We report on the development of the theory of second-harmonic generation by an incoherent pump with broad angular and frequency spectra. We show that spatial as well as temporal walk-off effects in a nonlinear crystal result in angular dispersion of the second-harmonic radiation. We demonstrate that the acceptance angle in second-harmonic generation by incoherent light is caused by the width of the pump angular spectrum and the resulting angular dispersion of second-harmonic radiation but does not depend on crystal length. In this case the frequency spectrum of second-harmonic radiation is determined by its angular dispersion and the pump angular spectrum. The theory is supported by an experiment in which a LiIO{sub 3} crystal was pumped by a tungsten halogen lamp.

  17. Study on the second harmonic generation of tunable TEA CO2 laser in quasi-phase-matched GaAs crystal

    NASA Astrophysics Data System (ADS)

    Zheng, Yijun; Li, Qiang; Tan, Rongqing; Wang, Hao

    2015-10-01

    In this paper, on the basis of the theory of quasi phase matched, CO2 laser spectrum corresponding to GaAs chip within the scope of the matching length was calculated. Through the numerical solution of the wave equation, the relationship between power density of pump laser and frequency doubling conversion efficiency was given under the different crystal length conditions. By adjusting the CO2 laser gas mixture components, we optimized the pump laser pulse wave to meet the requirements in the temporal distribution of the pump light. On the other hand, we optimize the output beam mode to meet the pump light distribution in space requirements. We use the tunable TEA CO2 laser as the light source to pump quasi phase matching GaAs crystal, When the pump wavelength is changed from 9.23μm to 10.75μm range, the conversion efficiency of frequency doubling output is greater than 4%, when the pump wavelength is 10.68um, the frequency doubling efficiency reached 6.58%.

  18. Investigation of intracavity third-harmonic generation at 1.06 μm in YCa4O(BO3)3 crystals

    NASA Astrophysics Data System (ADS)

    Du, C.; Wang, Z.; Liu, J.; Xu, X.; Fu, K.; Xu, G.; Wang, J.; Shao, Z.

    Intracavity sum-frequency mixing of 1.06 μm and 532 nm in YCa4O(BO3)3 (YCOB) crystals cut for different type-I phase-matching directions of (θ,ϕ)=(106°,77.2°), (111°, 79.6°) and (65°, 82.8°) was investigated in a compact diode-end-pumped acousto-optical Q-switched Nd:YVO4/KTP laser formed with a three-mirror folded resonator. The maximum 355-nm average output power of 124 mW was obtained in the phase-matching direction of (106°, 77.2°) with a pump-to-ultraviolet conversion efficiency of 3.3% at the repetition frequency of 20 kHz.

  19. Squeezed light from second-harmonic generation: experiment versus theory.

    PubMed

    Ralph, T C; Taubman, M S; White, A G; McClelland, D E; Bachor, H A

    1995-06-01

    We report excellent quantitative agreement between theoretical predictions and experimental observation of squeezing from a singly resonant second-harmonic-generating crystal. Limitations in the noise suppression imposed by the pump laser are explicitly modeled and confirmed by our measurements.

  20. Third-harmonic performance of the Beamlet prototype laser

    SciTech Connect

    Wegner, P.J.; Barker, C.E.; Caird, J.A.; Dixit, S.N.; Henesian, M.A.; Seppala, L.G.; Thompson, C.E.; Van Wonterghem, B.V.

    1997-01-31

    The Beamlet laser is a nearly full-scale, single-aperture prototype of the driver design for the National Ignition Facility (NIF). As part of a test and validation plan for the NIF design, Beamlet was recently equipped with final focusing optics and diagnostics for the purpose of evaluating integrated component performance and equivalent target-plane irradiance conditions at the 0.351-{mu}m output wavelength specified for NIF targets. A 37-cm aperture two-crystal converter scheme generates the third harmonic of the Nd:glass 1.053-{mu}m wavelength with high efficiency. The efficiency of the converter has been characterized and is reported, along with detailed measurements of the near-field and far-field UV irradiance distributions at operating conditions up to and exceeding red-line levels for the NIF. Dependences of observed beam quality on critical laser parameters including output power, B-integral, and spatial filtering are discussed and compared with numerical simulations.

  1. Measurement of submilliwatt, picosecond terahertz emission from a femtosecond-laser-pumped solid-state dc to ac radiation converter based on a ZnSe crystal

    SciTech Connect

    Yugami, Noboru; Ohata, Nobuo; Yaegashi, Kenta; Kawanago, Hiroshi

    2006-11-15

    We measured the terahertz pulse emission from a femtosecond-laser-pumped solid-state dc to ac radiation converter using a 150 fs Ti:sapphire laser pulse for dense plasma diagnostics. The laser-produced ionization front was directly modulated from a periodic electrostatic field to pulsed emission. The central frequency of the emission was measured to be 0.13 THz having a bandwidth of 0.1 THz and a peak power of 0.2 mW. This emission source is suitable for use in various novel diagnostic techniques, such as dense plasma diagnostics.

  2. Design and Analysis of the Main AC/DC Converter System for ITER

    NASA Astrophysics Data System (ADS)

    Sheng, Zhicai; Xu, Liuwei; Fu, Peng

    2012-04-01

    A design of the main AC/DC converter system for ITER is described and the configuration of the main AC/DC converters is presented. To reduce the reactive power absorbed from the converter units, the main AC/DC converters are designed to be series-connected and work in a sequential mode. The structure of the regulator of the converter system is described. A simulation model was built up for the PSCAD/EMTDC code, and the design was validated accordingly. Harmonic analysis and reactive power calculation of the converters units are presented. The results reveal the advantage of sequential control in reducing reactive power and harmonics.

  3. Convertible Stadium

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Air flotation technology used in NASA's Apollo program has found an interesting application in Hawaii's Aloha Stadium near Honolulu. The stadium's configuration can be changed, by moving entire 7,000-seat sections on a cushion of air, for best accommodation of spectators and participants at different types of events. In most stadiums, only a few hundred seats can be moved, by rolling sections on wheels or rails. At Aloha Stadium, 28,000 of the 50,000 seats can be repositioned for better spectator viewing and, additionally, for improved playing conditions. For example, a stadium designed primarily for football may compromise the baseball diamond by providing only a shallow outfield. Aloha's convertibility allows a full-size baseball field as well as optimum configurations for many other types of sports and special events. The photos show examples. The stadium owes its versatility to air flotation technology developed by General Motors. Its first large-scale application was movement of huge segments of the mammoth Saturn V moonbooster during assembly operations at Marshall Space Flight Center.

  4. Thermionic converter

    DOEpatents

    Rasor, Ned S.; Britt, Edward J.

    1976-01-01

    A gas-filled thermionic converter is provided with a collector and an emitter having a main emitter region and an auxiliary emitter region in electrical contact with the main emitter region. The main emitter region is so positioned with respect to the collector that a main gap is formed therebetween and the auxiliary emitter region is so positioned with respect to the collector that an auxiliary gap is formed therebetween partially separated from the main gap with access allowed between the gaps to allow ionizable gas in each gap to migrate therebetween. With heat applied to the emitter the work function of the auxiliary emitter region is sufficiently greater than the work function of the collector so that an ignited discharge occurs in the auxiliary gap and the work function of the main emitter region is so related to the work function of the collector that an unignited discharge occurs in the main gap sustained by the ions generated in the auxiliary gap. A current flows through a load coupled across the emitter and collector due to the unignited discharge in the main gap.

  5. Controlling Second Harmonic Efficiency of Laser Beam Interactions

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

    2011-01-01

    A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact.

  6. Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, D. (Editor); Kim, Y. S. (Editor); Zachary, W. W. (Editor)

    1993-01-01

    Proceedings of a workshop on Harmonic Oscillators held at the College Park Campus of the University of Maryland on March 25 - 28, 1992 are presented. The harmonic oscillator formalism is playing an important role in many branches of physics. This is the simplest mathematical device which can connect the basic principle of physics with what is observed in the real world. The harmonic oscillator is the bridge between pure and applied physics.

  7. Research on fiber-optic sensors for methane detection based on Harmonic detection

    NASA Astrophysics Data System (ADS)

    Wang, Shutao; Huang, Liang; Zhou, Zhishuang; Zhu, Zhihui

    2010-10-01

    In this paper, a sylstem of fiber-optic gas sensor based methane absorption spectra is studied. The system have made great improvement and in-depth analysis in methane spectral absorption,a weak optical signal extraction and processing and gas measurement accuracy.The system consists of light source, Photonic Crystal Fiber, air chamber, photoelectric detectors and signal processing components and so on. According to the Lambert-Beer law, spectrum absorption intensity is closely relate with the concentration of the gas. In order to ensure the system at a high resolution and sensitivity,The system used distributed feedback semiconductor laser (DFBLD) as a light source .It bring useful information of the optical signal to PIN Photodetector which then convert the optical signal to electrical signals after optical interacting with the methane gas,then send the electrical signal to lock-in amplifier.the harmonic detection of gas concentration was achieved by the light modulator, And then compared the harmonic component. Finally, the signal expected was produced through the A / D converter digital in the computer.

  8. Covariant harmonic oscillators and coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo; Kim, Young S.; Noz, Marilyn E.

    1995-01-01

    It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.

  9. Nonlinear harmonic generation in the STARS FEL

    NASA Astrophysics Data System (ADS)

    Abo-Bakr, M.; Goldammer, K.; Kamps, T.; Knobloch, J.; Kuske, B.; Leitner, T.; Meseck, A.

    2008-08-01

    BESSY proposes to build STARS, an FEL to demonstrate cascaded High Gain Harmonic Generation (HGHG). In two HGHG stages, a laser source of 700-900 nm is converted down to a wavelength of 40-70 nm. The STARS facility consists of a normal-conducting RF photoinjector, three superconducting TESLA-type acceleration modules, a magnetic bunch compressor and two stages of HGHG, each consisting of a modulator, dispersive chicane and a radiator. At the entrance of the undulator section, the beam energy is 325 MeV and the peak current is about 500 A. With these parameters, the STARS FEL reaches saturation with a peak power of 100-350 MW. A superradiant mode is also foreseen which boosts the radiation power to the GW-level. Due to nonlinear harmonic generation (NHG), free electron lasers also radiate coherently at higher harmonics of the FEL resonant frequency. STARS can hence extend its output range to even shorter wavelengths. This paper presents studies of the STARS harmonic content in the wavelength range of 6-20 nm. Seeding with high harmonic generation pulses at 32 nm is also discussed.

  10. Microwave harmonic generation and nonlinearity in microplasmas

    NASA Astrophysics Data System (ADS)

    Gregório, José; Parsons, Stephen; Hopwood, Jeffrey

    2016-06-01

    Nonlinearities in microplasmas excited by microwaves are described both experimentally and through a 2D fluid model. A split-ring resonator generates a microplasma in a 150 μm discharge gap at 1 GHz. Nonlinearity generates both radiated and conducted harmonics which are measured from 0.2–760 Torr (Ar) for power levels between 0.5 and 3 W. Asymmetric electrode configurations produce the highest 3rd harmonic power (>10 mW) at an optimal pressure of the order of 0.3 Torr. The microplasma is also demonstrated as a mixer. The experimental results are explained with the aid of a fluid model of the microplasma. The model shows that the smaller electrode in an asymmetric device is forced to attain a large microwave potential that strongly modulates the sheath thickness and the local electron energy. The voltage-dependent sheath width gives rises to a nonlinear sheath capacitance as well as short pulses of hot electron flux to the electrode. The modeled 3rd harmonic current is converted to an extractable harmonic power by a microwave circuit model. Using this technique the modeled and measured harmonic production of the microplasma are found to compare favorably.

  11. System and methods for reducing harmonic distortion in electrical converters

    DOEpatents

    Kajouke, Lateef A; Perisic, Milun; Ransom, Ray M

    2013-12-03

    Systems and methods are provided for delivering energy using an energy conversion module. An exemplary method for delivering energy from an input interface to an output interface using an energy converison module coupled between the input interface and the output interface comprises the steps of determining an input voltage reference for the input interface based on a desired output voltage and a measured voltage and the output interface, determining a duty cycle control value based on a ratio of the input voltage reference and the measured voltage, operating one or more switching elements of the energy conversion module to deliver energy from the input interface to the output interface to the output interface with a duty cycle influenced by the dute cycle control value.

  12. Harmonization Initiatives in Europe

    PubMed Central

    2016-01-01

    Introduction Modern medicine is more and more based on protocols and guidelines; clinical laboratory data play very often a relevant role in these documents and for this reason the need for their harmonization is increasing. To achieve harmonized results the harmonization process must not be limited to only the analytical part, but has to include the pre- and the post-analytical phases. Results To fulfill this need the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) has started several initiatives. A Working Group on harmonization of the total testing process (WG-H) has been created with the aims of: 1) surveying and summarizing national European and pan European harmonization initiatives; 2) promoting and coordinating the dissemination of especially promising harmonization initiatives among the EFLM member societies; and 3) taking initiatives to harmonize nomenclature, units and reference intervals at a European level. The activity of the WG started this year with a questionnaire targeted at surveying the status of various harmonization activities, especially those in the pre- and post-analytical phase categories, among the European laboratory medicine societies. Conclusions Based on the results of the questionnaire, some activities promoting the dissemination of best practice in blood sampling, sample storage and transportation, in collaboration with WG on the pre-analytical phase, will be promoted, and initiatives to spread to all the European countries the use of SI units in reporting, will be undertaken. Moreover, EFLM has created a Task and Finish Group on standardization of the color coding for blood collection tube closures that is actively working to accomplish this difficult task through collaboration with manufacturers. PMID:27683503

  13. Harmonic 'signatures' of microorganisms.

    PubMed

    Blake-Coleman, B C; Hutchings, M J; Silley, P

    1994-01-01

    The frequency/amplitude effect of various microorganisms exposed to periodic (time varying) electric fields, when proximate to immersed electrodes, has been studied using a novel analytical instrument. The harmonic distribution, in complex signals caused by cells exposed to harmonic free waveforms and occupying part of the electrode/suspension interface volume, was shown to be almost entirely due to the change in the standing interfacial transfer function by the (dielectrically nonlinear) presence of cells. Thus, the characteristic interfacial non-linearity is viewed as variable, being uniquely modulated by the presence of particular cells in the interfacial region. Little can be attributed to bulk (far field) effects. The tendency for subtle (characteristic) signal distortion to occur as a function of particulate (cell or molecular) occupancy of the near electrode interfacial region under controlled current conditions leads to the method of sample characterisation by harmonic (Fourier) analysis. We report here, as a sequel to our original studies (Hutchings et al., 1993; Hutchings and Blake-Coleman, 1993), preliminary results of the harmonic analysis of microbial suspensions under controlled signal conditions using a three-electrode configuration. These data provide three-dimensional graphical representations producing harmonic 'surfaces' for various microorganisms. Thus, cell type differences are characterised by their 'harmonic signature'. The visual distinction provided by these 'surface' forming three-dimensional plots is striking and gives a convincing impression of the ability to identify and enumerate specific microorganisms by acquisition of cell-modulated electrode interfacial Fourier spectra. PMID:8060593

  14. Higher harmonic generation microscopy.

    PubMed

    Sun, Chi-Kuang

    2005-01-01

    Higher harmonic-generation, including second harmonic generation and third harmonic generation, leaves no energy deposition to the interacted matters due to its virtual-level transition characteristic, providing a truly non-invasive modality and is ideal for in vivo imaging of live specimens without any preparation. Second harmonic generation microscopy provides images on stacked membranes and arranged proteins with organized nano-structures due to the bio-photonic crystalline effect. Third harmonic generation microscopy provides general cellular or subcellular interface imaging due to optical inhomogeneity. Due to their virtual-transition nature, no saturation or bleaching in the generated signal is expected. With no energy release, continuous viewing without compromising sample viability can thus be achieved. Combined with its nonlinearity, higher harmonic generation microscopy provides sub-micron three-dimensional sectioning capability and millimeter penetration in live samples without using fluorescence and exogenous markers, offering morphological, structural, functional, and cellular information of biomedical specimens without modifying their natural biological and optical environments.

  15. Semiconductor converters/inverters for photovoltaic power supply

    NASA Astrophysics Data System (ADS)

    Longrigg, P.

    The two generic types of DC to AC inverters are discussed, considering inherent problems and prospects for solution. A current source converter uses reference current from the AC utility line to chop the DC into AC using four thyristors as switches. Difficulties exist in that DC current contains lagging quadrature currents and are harmonics rich. Solutions are indicated in the form of tuned filters for controlling harmonics and a static VAR generator for the quadrature demand, except that solving the quadrature problem reintroduces further harmonics. In the voltage-sourced converter, which performs much like a synchronous generator, harmonics are also present and can be eliminated with pulse-width modulation. However, at lower powers, switching accelerates beyond attainable switching speed levels. Finally, a current-fed, force commutated converter is described which commutates ahead of the AC voltage; it may need special filters or buffers in addition to harmonics filters. Further studies are recommended in areas of cost reductions, interface overvoltage protection, harmonics, source stability, safety and code requirements, and utility system protection, all pertinent to photovoltaic power conditioning. Circuitry diagrams and AC V-I graphs are provided.

  16. High-order harmonic generation in solids: A unifying approach

    NASA Astrophysics Data System (ADS)

    Luu, Tran Trung; Wörner, Hans Jakob

    2016-09-01

    There have been several experimental reports showing high-order harmonic generation from solids, but there has been no unifying theory presented as of yet for all these experiments. Here we report on the systematic investigation of high-order harmonic generation within the semiconductor Bloch equations, taking into account multiple bands and relaxation processes phenomenologically. In addition to reproducing key experiments, we show the following: (i) Electronic excitations, direct-indirect excitation pathways, and relaxation processes are responsible for high-order harmonic generation and control using midinfrared drivers in zinc oxide. We describe an intuitive picture explaining a two-color experiment involving noninversion symmetric crystals. (ii) High-order harmonic generation can be considered as a general feature of ultrafast strong-field-driven electronic dynamics in solids. We demonstrate this statement by predicting high-order harmonic spectra of solids that have not been studied yet.

  17. Spatiotemporal toroidal waves from the transverse second-harmonic generation.

    PubMed

    Saltiel, Solomon M; Neshev, Dragomir N; Fischer, Robert; Krolikowski, Wieslaw; Arie, Ady; Kivshar, Yuri S

    2008-03-01

    We study the second-harmonic generation via transversely matched interaction of two counterpropagating ultrashort pulses in chi(2) photonic structures. We show that the emitted second-harmonic wave attains the form of spatially expanding toroid with the initial thickness given by the cross correlation of the pulses. We demonstrate the formation of such toroidal waves in crystals with random ferroelectric domains as well as in annularly poled nonlinear photonic structures.

  18. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

  19. Harmonics in a Wind Power Plant: Preprint

    SciTech Connect

    Preciado, V.; Madrigal, M.; Muljadi, E.; Gevorgian, V.

    2015-04-02

    Wind power generation has been growing at a very fast pace for the past decade, and its influence and impact on the electric power grid is significant. As in a conventional power plant, a wind power plant (WPP) must ensure that the quality of the power being delivered to the grid is excellent. At the same time, the wind turbine should be able to operate immune to small disturbances coming from the grid. Harmonics are one of the more common power quality issues presented by large WPPs because of the high switching frequency of the power converters and the possible nonlinear behavior from electric machines (generator, transformer, reactors) within a power plant. This paper presents a summary of the most important issues related to harmonics in WPPs and discusses practical experiences with actual Type 1 and Type 3 wind turbines in two WPPs.

  20. Nonlinearly coupled localized plasmon resonances: Resonant second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Ginzburg, Pavel; Krasavin, Alexey; Sonnefraud, Yannick; Murphy, Antony; Pollard, Robert J.; Maier, Stefan A.; Zayats, Anatoly V.

    2012-08-01

    The efficient resonant nonlinear coupling between localized surface plasmon modes is demonstrated in a simple and intuitive way using boundary integral formulation and utilizing second-order optical nonlinearity. The nonlinearity is derived from the hydrodynamic description of electron plasma and originates from the presence of material interfaces in the case of small metal particles. The coupling between fundamental and second-harmonic modes is shown to be symmetry selective and proportional to the spatial overlap between polarization dipole density of the second-harmonic mode and the square of the polarization charge density of the fundamental mode. Particles with high geometrical symmetry will convert a far-field illumination into dark nonradiating second-harmonic modes, such as quadrupoles. Effective second-harmonic susceptibilities are proportional to the surface-to-volume ratio of a particle, emphasizing the nanoscale enhancement of the effect.

  1. Harmonic uniflow engine

    DOEpatents

    Bennett, Charles L.

    2016-03-22

    A reciprocating-piston uniflow engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. When released, the inlet valve head undergoes a single oscillation past the equilibrium position to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. In other embodiments, the harmonic oscillator arrangement of the inlet valve enables the uniflow engine to be reversibly operated as a uniflow compressor.

  2. Single-switch 3{phi} PWM low harmonic rectifiers

    SciTech Connect

    Ismail, E.H.; Erickson, R.

    1996-03-01

    Existing 3{phi} ac-dc low-harmonic rectifiers are costly and require complex control schemes to minimize input current harmonics. Introduced here are two new classes of low cost 3{phi} ac-dc high power factor/low harmonic controlled rectifiers. These are derived from parent dc-dc converter topologies containing boost-type inputs and buck-type inputs. With a single active switch in addition to the diode bridge rectifier, the converters are capable of drawing a high-quality input current waveform naturally at nearly unit power factor. Thus, a simple 3{phi} ac-dc high power factor rectifier is obtained. Two algorithms are introduced in this paper for constructing a 3{phi} ac-dc high-quality rectifier. These algorithms depend on the simple switched-mode boost-type input converter and buck-type input converter modified by an input filter. For most known dc-dc converters which belong to these classes, there are corresponding 3{phi} ac-dc high power factor topologies, which use the same number of transistors and use six additional fast diodes. Analytical and simulation results are supplied to demonstrate the validity of the concept.

  3. Harmonic Frequency Lowering

    PubMed Central

    Kirchberger, Martin

    2016-01-01

    A novel algorithm for frequency lowering in music was developed and experimentally tested in hearing-impaired listeners. Harmonic frequency lowering (HFL) combines frequency transposition and frequency compression to preserve the harmonic content of music stimuli. Listeners were asked to make judgments regarding detail and sound quality in music stimuli. Stimuli were presented under different signal processing conditions: original, low-pass filtered, HFL, and nonlinear frequency compressed. Results showed that participants reported perceiving the most detail in the HFL condition. In addition, there was no difference in sound quality across conditions. PMID:26834122

  4. Booster double harmonic setup notes

    SciTech Connect

    Gardner, C. J.

    2015-02-17

    The motivation behind implementing a booster double harmonic include the reduced transverse space charge force from a reduced peak beam current and reduced momentum spread of the beam, both of which can be achieved from flattening the RF bucket. RF capture and acceleration of polarized protons (PP) is first set up in the single harmonic mode with RF harmonic h=1. Once capture and acceleration have been set up in the single harmonic mode, the second harmonic system is brought on and programmed to operate in concert with the single harmonic system.

  5. A Harmonic Motion Experiment

    ERIC Educational Resources Information Center

    Gluck, P.; Krakower, Zeev

    2010-01-01

    We present a unit comprising theory, simulation and experiment for a body oscillating on a vertical spring, in which the simultaneous use of a force probe and an ultrasonic range finder enables one to explore quantitatively and understand many aspects of simple and damped harmonic motions. (Contains 14 figures.)

  6. Introducing Simple Harmonic Motion.

    ERIC Educational Resources Information Center

    Roche, John

    2002-01-01

    Explains the origin and significance of harmonic motion which is an important topic that has wide application in the world. Describes the phenomenon by using an auxiliary circle to help illustrate the key relationships between acceleration, displacement, time, velocity, and phase. (Contains 16 references.) (Author/YDS)

  7. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  8. Stress in Harmonic Serialism

    ERIC Educational Resources Information Center

    Pruitt, Kathryn Ringler

    2012-01-01

    This dissertation proposes a model of word stress in a derivational version of Optimality Theory (OT) called Harmonic Serialism (HS; Prince and Smolensky 1993/2004, McCarthy 2000, 2006, 2010a). In this model, the metrical structure of a word is derived through a series of optimizations in which the "best" metrical foot is chosen…

  9. Voltage source ac-to-dc converters for high-power transmitters

    NASA Technical Reports Server (NTRS)

    Cormier, R.

    1990-01-01

    This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.

  10. Design of precision mounts for optimizing the conversion efficiency of KDP crystals for the National Ignition Facility

    SciTech Connect

    Hibbard, R.L., LLNL

    1998-03-30

    A key design challenge for the National Ignition Facility (NIF), being constructed at Lawrence Livermore National Laboratory (LLNL), [Hibbard, R L , 1998], is the frequency converter consisting of two KDP crystals and a focusing lens Frequency conversion is a critical performance factor for NIF and the optical mount design for this plays a key role in meeting design specifications The frequency converter is a monolithic cell that mounts the optics and is the point on the beamline where the frequency conversion crystals are optimally aligned and the cell is focused on target The lasing medium is neodymium in phosphate glass with a fundamental frequency (1{omega}) of 1 053 {micro}m Sum frequency generation in a pair of conversion crystals (KDP/KD*P) produces 1 8 MJ of the third harmonic light (3{omega} or {lambda}=O 35 pm). The phase-matching scheme on NIF is type I second harmonic generation followed by type II sum-frequency-mixing of the residual fundamental and the second harmonic light This laser unlike previous laser system designs, must achieve high conversion efficiency, 85%, which is close to the 90 8% theoretical maximum As a result, this design is very sensitive to angular variations in beam propagation and in the crystal axes orientation. Factors that influence the phase matching angle include crystal inhomogeneity, residual and induced stress in the crystals, the crystals` natural and mounted surface figure, mounting imperfections and gravity sag These angular variations need to be controlled within a 40 {micro}rad error budget. The optical mount contributions to the angular error budget are 20 {micro}rad and are what make the frequency converter in the Final Optics Cell (FOC) such a challenging precision design. The premise of using full edge support in the FOC design is primarily driven by the spherical target chamber design that has optics mounted at multiple longitudinal angles and thus gravity sag in the crystals that needs to be minimized To meet

  11. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Gill, J. C.; Earle, R. V.; Mar, H. M.

    1982-01-01

    The objective of the Rotorcraft Convertible Engine Study was to define future research and technology effort required for commercial development by 1988 of convertible fan/shaft gas turbine engines for unconventional rotorcraft transports. Two rotorcraft and their respective missions were defined: a Fold Tilt Rotor aircraft and an Advancing Blade Concept (ABC) rotorcraft. Sensitivity studies were conducted with these rotorcraft to determine parametrically the influence of propulsion characteristics on aircraft size, mission fuel requirements, and direct operating costs (DOC). The two rotorcraft were flown with conventional propulsion systems (separate lift/cruise engines) and with convertible propulsion systems to determine the benefits to be derived from convertible engines. Trade-off studies were conducted to determine the optimum engine cycle and staging arrangement for a convertible engine. Advanced technology options applicable to convertible engines were studied. Research and technology programs were identified which would ensure technology readiness for commercial development of convertible engines by 1988.

  12. Harmonization, Trade, and the Environment.

    ERIC Educational Resources Information Center

    Stevens, Candice

    1993-01-01

    Discusses the harmonization of international methods for the development and administration of product standards. Defines the term "harmonization" and discusses the harmonization of environmental policies and purposes involving product standards; environmental regulations on production methods, technologies, and practices; and life-cycle…

  13. Harmonic Golay coded excitation based on harmonic quadrature demodulation method.

    PubMed

    Kim, Sang-Min; Song, Jae-Hee; Song, Tai-Kyong

    2008-01-01

    Harmonic coded excitation techniques have been used to increase SNR of harmonic imaging with limited peak voltage. Harmonic Golay coded excitation, in particular, generates each scan line using four transmit-receive cycles, unlike conventional Golay coded excitation method, thus resulting in low frame rates. In this paper we propose a method of increasing the frame rate of said method without impacting the image quality. The proposed method performs two transmit-receive cycles using QPSK code to ensure that the harmonic components of incoming signals are Golay coded and uses harmonic quadrature demodulation to extract compressed second harmonic component only. The proposed method has been validated through mathematical analysis and MATLAB simulation, and has been verified to yield a limited error of -52.08dB compared to the ideal case. Therefore, the proposed method doubles the frame rate compared to the existing harmonic Golay coded excitation method without significantly deteriorating the image quality.

  14. Optical third-harmonic generation using ultrashort laser pulses

    SciTech Connect

    Stoker, D.; Keto, J.W.; Becker, M.F.

    2005-06-15

    To better predict optical third-harmonic generation (THG) in transparent dielectrics, we model a typical ultrashort pulsed Gaussian beam, including both group velocity mismatch and phase mismatch of the fundamental and harmonic fields. We find that competition between the group velocity mismatch and phase mismatch leads to third-harmonic generation that is sensitive only to interfaces. In this case, the spatial resolution is determined by the group velocity walk-off length. THG of modern femtosecond lasers in optical solids is a bulk process, without a surface susceptibility, but bears the signature of a surface enhancement effect in z-scan measurements. We demonstrate the accuracy of the model, by showing the agreement between the predicted spectral intensity and the measured third-harmonic spectrum from a thin sapphire crystal.

  15. Diode-end-pumped solid-state ultraviolet laser based on intracavity third-harmonic generation of 1.06 μm in YCa 4O(BO 3) 3 crystal

    NASA Astrophysics Data System (ADS)

    Du, Chenlin; Wang, Zhengping; Xu, Guibao; Liu, Junhai; Xu, Xinguang; Fu, Kun; Wang, Jiyang; Shao, Zongshu

    2002-11-01

    Intracavity type-I sum-frequency mixing of 1.06 μm and 532 nm with a ( θ, ϕ)=(106°,77.2°)-cut YCOB crystal was performed in a compact laser-diode-pumped solid-state laser. Three type-II phase-matching KTP crystals with different length were used to generate 532 nm light by frequency-doubling of 1.06 μm. The 355 nm output power was measured with the three KTP crystals for Q-switched and continuous-wave (CW) operation, respectively. The maximum ultraviolet output power of 1305 μW was obtained with a 15 mm KTP crystal for CW operation, while the maximum ultraviolet average output power of 124 mW was obtained with a 10 mm KTP crystal for Q-switched operation.

  16. Harmonic multiplication using resonant tunneling

    NASA Technical Reports Server (NTRS)

    Sollner, T. C. L. G.; Brown, E. R.; Goodhue, W. D.; Correa, C. A.

    1988-01-01

    This paper demonstrates the use of resonant-tunneling diodes as varistors for harmonic multiplication. It is shown that efficient odd-harmonic conversion is possible and that even harmonics do not appear because of the antisymmetry of the current-voltage (I-V) curve. It is also shown that, with the proper choice of resonant-tunneling structure and pump amplitude, most of the harmonic output power can be confined to a single odd-harmonic frequency. Fifth-harmonic multiplication was demonstrated with an output at 21.75 GHz and a power conversion efficiency of 0.5 percent, and a fifth-harmonic efficiency of 2.7 percent was achieved in a circuit simulation using an improved I-V curve.

  17. Power line carrier interference from HVDC converter terminals

    SciTech Connect

    Tatro, P.J.; Adamson, K.A. ); Eitzmann, M.A.; Smead, M. . Power Systems Engineering Dept.)

    1993-07-01

    Power line carrier (PLC) equipment typically operates in the frequency range from 25 kHz to 300 kHz. Interference studies for HVDC converters usually concentrate on interference from noise sources within this frequency range. However, operating experience at the Sandy Pond converter terminal has indicated that PLC equipment is also susceptible to interference from sources of power system harmonics below the PLC frequency range. Extensive field testing and analytical studies have shown that each PLC circuit has a resonant frequency below the operating frequency. If excited at this resonant frequency, high voltages may exist within the PLC circuit. The resulting saturation of PLC components leads to local generation of radio frequency (RF) noise that interferes with proper operation of PLC circuits. Sources of power system harmonics in the 3-10 kHz range, such as line commutated dc converters, are potential sources of this type of interference.

  18. ITER convertible blanket evaluation

    SciTech Connect

    Wong, C.P.C.; Cheng, E.

    1995-09-01

    Proposed International Thermonuclear Experimental Reactor (ITER) convertible blankets were reviewed. Key design difficulties were identified. A new particle filter concept is introduced and key performance parameters estimated. Results show that this particle filter concept can satisfy all of the convertible blanket design requirements except the generic issue of Be blanket lifetime. If the convertible blanket is an acceptable approach for ITER operation, this particle filter option should be a strong candidate.

  19. Interleaved power converter

    DOEpatents

    Zhu, Lizhi

    2007-11-13

    A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DC converters with three rather than four high voltage inverter legs.

  20. Three-dimensional simulations of harmonic radiation and harmonic lasing

    NASA Astrophysics Data System (ADS)

    Schmitt, Mark J.; McVey, Brian D.

    Characteristics of the harmonic emission from free electron lasers (FELs) are examined in the spontaneous, coherent-spontaneous and stimulated emission regimes. The radiation at both odd and even harmonic frequencies is treated for electron beams with finite emittance and energy spread. In the spontaneous emission regime, the transverse radiation patterns including the transverse frequency dependences, are given. How this expression is modified to include energy spread and emittance is described. In the coherent-spontaneous emission and stimulated emission regimes, the interaction of the radiation fields with the electrons must be treated self consistently. Here, a single frequency distributed transverse source function for each electron is used in the harmonic version of the 3-D code FELEX to model the harmonic radiation. The code has recently been modified to simultaneously model the fundamental and harmonic interactions for multiple-pass oscillator simulations. These modifications facilitate the examination of FELs under various operating conditions. When the FEL is lasing at the fundamental, the evolution of the harmonic fields can be examined. This evolution is unique in the sense that the electron beam radiates at the harmonic frequencies in the presence of the harmonic radiation circulating in the cavity. As a result, enhancements of the harmonic emission can be observed. Finally, harmonic lasing can occur in cases where there is sufficient gain to overcome cavity losses and lasing at the fundamental can be suppressed. The characteristics and efficiency of these interactions are explored.

  1. Three-dimensional simulations of harmonic radiation and harmonic lasing

    NASA Astrophysics Data System (ADS)

    Schmitt, Mark J.; McVey, Brian D.

    1991-07-01

    Characteristics of the harmonic emission from free electron lasers (FELs) are examined in the spontaneous, coherent-spontaneous and stimulated emission regimes. The radiation at both odd and even harmonic frequencies is treated for electron beams with finite emittance and energy spread. In the spontaneous emission regime, the transverse radiation patterns including the transverse frequency dependences, are given. How this expression is modified to include energy spread and emittance is described. In the coherent-spontaneous emission and stimulated emission (lasing) regimes, the interaction of the radiation fields with the electrons must be treated self-consistently. Here, a single-frequency distributed transverse source function for each electron is used in the harmonic version (HELEX) of the 3D code FELEX to model the harmonic radiation. This code has recently been modified to simultaneously model the fundamental and harmonic interactions for multiple-pass oscillator simulations. These modifications facilitate the examination of FELs under various operating conditions. When the FEL is lasing at the fundamental, the evolution of the harmonic fields can be examined. This evolution is unique in the sense that the electron beam (which is bunched by the fundamental optical field) radiates at the harmonic frequencies in the presence of the harmonic radiation circulating in the cavity. As a result, enhancements of the harmonic emission can be observed. Finally, harmonic lasing can occur in cases where there is sufficient gain to overcome cavity losses and lasing at the fundamental can be suppressed. The characteristics and efficiency of these interactions are explored.

  2. Improved Active Harmonic Current Elimination Based on Voltage Detection

    PubMed Central

    Tan, Tianyuan; Dong, Shuan; Huang, Yingwei; Liu, Jian; Le, Jian; Liu, Kaipei

    2016-01-01

    With the increasing penetration of power electronic equipment in modern residential distribution systems, harmonics mitigation through the distributed generation (DG) interfacing converters has received significant attention. Among recently proposed methods, the so-called active resonance damper (ARD) and harmonic voltage compensator (HVC) based on voltage detection can effectively reduce the harmonic distortions in selected areas of distribution systems. However, it is found out that when traditional ARD algorithm is used to eliminate harmonic current injected by non-linear loads, its performance is constrained by stability problems and can at most eliminate half of the load harmonic currents. Thus, inspired by the duality between ARD and HVC, this paper presents a novel improved resistive active power filter (R-APF) algorithm based on integral-decoupling control. The design guideline for its parameters is then investigated through carefully analyzing the closed-loop poles’ trajectory. Computer studies demonstrate that the proposed algorithm can effectively mitigate the load harmonic currents and its performance is much better than traditional ARD based on proportional control. PMID:27295213

  3. Improved Active Harmonic Current Elimination Based on Voltage Detection.

    PubMed

    Tan, Tianyuan; Dong, Shuan; Huang, Yingwei; Liu, Jian; Le, Jian; Liu, Kaipei

    2016-01-01

    With the increasing penetration of power electronic equipment in modern residential distribution systems, harmonics mitigation through the distributed generation (DG) interfacing converters has received significant attention. Among recently proposed methods, the so-called active resonance damper (ARD) and harmonic voltage compensator (HVC) based on voltage detection can effectively reduce the harmonic distortions in selected areas of distribution systems. However, it is found out that when traditional ARD algorithm is used to eliminate harmonic current injected by non-linear loads, its performance is constrained by stability problems and can at most eliminate half of the load harmonic currents. Thus, inspired by the duality between ARD and HVC, this paper presents a novel improved resistive active power filter (R-APF) algorithm based on integral-decoupling control. The design guideline for its parameters is then investigated through carefully analyzing the closed-loop poles' trajectory. Computer studies demonstrate that the proposed algorithm can effectively mitigate the load harmonic currents and its performance is much better than traditional ARD based on proportional control. PMID:27295213

  4. Generating Second Harmonics In Nonlinear Resonant Cavities

    NASA Technical Reports Server (NTRS)

    Kozlovsky, William J.; Nabors, C. David; Byer, Robert L.

    1990-01-01

    Single-axial-mode lasers pump very-low-loss doubling crystals. Important advance in making resonant generation of second harmonics possible for diode-laser-pumped solid-state lasers is recent development of monolithic nonplanar ring geometries in neodymium:yttrium aluminum garnet (Nd:YAG) lasers that produce frequency-stable single-mode outputs. Other advance is development of high-quality MgO:LiNbO3 as electro-optically nonlinear material. Series of experiments devised to improve doubling efficiency of low-power lasers, and particularly of diode-laser-pumped continuous-wave Nd:YAG lasers.

  5. Polarization-controllable TE21 mode converter

    NASA Astrophysics Data System (ADS)

    Chang, T. H.; Yu, C. F.; Fan, C. T.

    2005-07-01

    We report the concept and development of a Ka-band mode and polarization converter that efficiently converts a TE10 rectangular waveguide mode into either a linearly or a circularly polarized TE21 cylindrical waveguide mode. The converter is composed of a power-dividing section, a mode-converting section, and a polarization-transitioning section. The converting process in each section is displayed and the working principles are discussed. A prototype has been built and tested. The measured results agree well with the numerical calculations for both linear and circular polarizations. The measured optimum back-to-back transmission is 94% with a 1-dB bandwidth of 4.1 GHz for the linear polarization. As for the circular polarization, the measured optimum transmission is 97%, but the corresponding bandwidth is indistinct due to some resonant dips. The reasons and impact for the dips are discussed. A bandwidth of 3.9 GHz is obtained for a single circular converter; meanwhile, an approach to eliminating these unwanted dips is presented in theory. For further diagnostics, the field pattern of either polarization is directly displayed on a temperature-sensitive liquid crystal display sheet, where the electric field strength can be discerned from the color spectrum. In addition to high conversion efficiency and broad bandwidth, this converter features easy construction, high mode purity, and polarization controllability.

  6. Multiresonant broadband optical antennas as efficient tunable nanosources of second harmonic light.

    PubMed

    Aouani, Heykel; Navarro-Cia, Miguel; Rahmani, Mohsen; Sidiropoulos, Themistoklis P H; Hong, Minghui; Oulton, Rupert F; Maier, Stefan A

    2012-09-12

    We report the experimental realization of efficient tunable nanosources of second harmonic light with individual multiresonant log-periodic optical antennas. By designing the nanoantenna with a bandwidth of several octaves, simultaneous enhancement of fundamental and harmonic fields is observed over a broad range of frequencies, leading to a high second harmonic conversion efficiency, together with an effective second order susceptibility within the range of values provided by widespread inorganic crystals. Moreover, the geometrical configuration of the nanoantenna makes the generated second harmonic signal independent from the polarization of the fundamental excitation. These results open new possibilities for the development of efficient integrated nonlinear nanodevices with high frequency tunability.

  7. Cascaded resonant bridge converters

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  8. Synthesis and analysis of harmonic-free three-phase inverters

    SciTech Connect

    Khan, I.A. . AC Delco Systems Div.); Erickson, R.W. . Dept. of Electrical and Computer Engineering)

    1994-11-01

    A systematic and straightforward procedure is developed for the synthesis and analysis of dc-to-three-phase-ac switched-mode converters. The procedure is useful in the derivation and design of converters with desirable characteristics such as harmonic-free power processing and low component stresses. Application of this procedure to a basic class of dc-to-three-phase-ac converters, namely, the four-topology single-inductor three-capacitor class leads to twenty-six converters in this class. This derivation is based on the assumption of processing power without the generation of supply-frequency harmonics. Other characteristics of converters include their ability to provide variable amplitude of output voltages both below and above the dc input value, variable frequency, and low component stresses.

  9. Microminiature thermionic converters

    DOEpatents

    King, Donald B.; Sadwick, Laurence P.; Wernsman, Bernard R.

    2001-09-25

    Microminiature thermionic converts (MTCs) having high energy-conversion efficiencies and variable operating temperatures. Methods of manufacturing those converters using semiconductor integrated circuit fabrication and micromachine manufacturing techniques are also disclosed. The MTCs of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. Existing prior art thermionic converter technology has energy conversion efficiencies ranging from 5-15%. The MTCs of the present invention have maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

  10. Converting Nonclassicality into Entanglement.

    PubMed

    Killoran, N; Steinhoff, F E S; Plenio, M B

    2016-02-26

    Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are "symmetric coherent states," connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality.

  11. Converting Nonclassicality into Entanglement.

    PubMed

    Killoran, N; Steinhoff, F E S; Plenio, M B

    2016-02-26

    Quantum mechanics exhibits a wide range of nonclassical features, of which entanglement in multipartite systems takes a central place. In several specific settings, it is well known that nonclassicality (e.g., squeezing, spin squeezing, coherence) can be converted into entanglement. In this work, we present a general framework, based on superposition, for structurally connecting and converting nonclassicality to entanglement. In addition to capturing the previously known results, this framework also allows us to uncover new entanglement convertibility theorems in two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are "symmetric coherent states," connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and nonlocal pictures of nonclassicality. PMID:26967398

  12. Digital scale converter

    DOEpatents

    Upton, Richard G.

    1978-01-01

    A digital scale converter is provided for binary coded decimal (BCD) conversion. The converter may be programmed to convert a BCD value of a first scale to the equivalent value of a second scale according to a known ratio. The value to be converted is loaded into a first BCD counter and counted down to zero while a second BCD counter registers counts from zero or an offset value depending upon the conversion. Programmable rate multipliers are used to generate pulses at selected rates to the counters for the proper conversion ratio. The value present in the second counter at the time the first counter is counted to the zero count is the equivalent value of the second scale. This value may be read out and displayed on a conventional seven-segment digital display.

  13. MODEL HARMONIZATION POTENTIAL AND BENEFITS

    EPA Science Inventory

    The IPCS Harmonization Project, which is currently ongoing under the auspices of the WHO, in the context of chemical risk assessment or exposure modeling, does not imply global standardization. Instead, harmonization is thought of as an effort to strive for consistency among appr...

  14. Harmonic Series Meets Fibonacci Sequence

    ERIC Educational Resources Information Center

    Chen, Hongwei; Kennedy, Chris

    2012-01-01

    The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?

  15. High-harmonic gyrotrons

    NASA Astrophysics Data System (ADS)

    McDermott, D. B.; Luhmann, N. C., Jr.

    1984-08-01

    There is currently much interest in the development of moderate to high power (1 kW - 1 MW) millimeter wave sources. Considered applications are mainly related to radar and communication systems. There are, however, also applications in plasma diagnostics, heating, and the nondestructive testing of dielectrics. The dominant source of high-power, high-frequency radiation has become the gyrotron. Jory et al. (1983) have reported operation of a 60 GHz, CW gyrotron, producing output powers in excess of 200 kW. High power, compact submillimeter-wave sources have become possible by making use of the concept of a high-harmonic gyrotron, in which the magnetic field can be reduced by an order of magnitude. Attention is given to synchronism, negative-mass instability, energy requirements, oscillators, efficiency, high power, dielectric loading, the peniotron, and amplifiers.

  16. Synchronous Discrete Harmonic Oscillator

    SciTech Connect

    Antippa, Adel F.; Dubois, Daniel M.

    2008-10-17

    We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2{pi} in phase space, is an integral multiple N of the discrete time step {delta}t. It is fully synchronous when N is even. It is pseudo-synchronous when T/{delta}t is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is ''blue shifted'' relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval {delta}t. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.

  17. Frequency doubling crystals

    DOEpatents

    Wang, Francis; Velsko, Stephan P.

    1989-01-01

    A systematic approach to the production of frequency conversion crystals is described in which a chiral molecule has attached to it a "harmonic generating unit" which contributes to the noncentrosymmetry of the molecule. Certain preferred embodiments of such harmonic generating units include carboxylate, guanadyly and imidazolyl units. Certain preferred crystals include L-arginine fluoride, deuterated L-arginine fluoride, L-arginine chloride monohydrate, L-arginine acetate, dithallium tartrate, ammonium N-acetyl valine, N-acetyl tyrosine and N-acetyl hydroxyproline. Chemical modifications of the chiral molecule, such as deuteration, halogenation and controlled counterion substitution are available to adapt the dispersive properties of a crystal in a particular wavelength region.

  18. Glycine lithium nitrate crystals

    NASA Astrophysics Data System (ADS)

    González-Valenzuela, R.; Hernández-Paredes, J.; Medrano-Pesqueira, T.; Esparza-Ponce, H. E.; Jesús-Castillo, S.; Rodriguez-Mijangos, R.; Terpugov, V. S.; Alvarez-Ramos, M. E.; Duarte-Möller, A.

    Crystals of glycine lithium nitrate with non-linear optical properties have been grown in a solution by slow evaporation at room temperature. The crystal shows a good thermal stability from room temperature to 175 °C where the crystal begins to degrade. This property is desirable for future technological applications. Also, a good performance on the second harmonic generation was found, characterizing the emitted dominant wavelength by a customized indirect procedure using luminance and chromaticity measured data based on the CIE-1931 standard. Additionally, the 532 nm signal was detected by using a variant to the Kurtz and Perry method.

  19. Algal Supply System Design - Harmonized Version

    SciTech Connect

    Abodeely, Jared; Stevens, Daniel; Ray, Allison; Newby, Deborah; Schaller, Kastli

    2013-03-01

    The objective of this design report is to provide an assessment of current technologies used for production, dewatering, and converting microalgae cultivated in open-pond systems to biofuel. The original draft design was created in 2011 and has subsequently been brought into agreement with the DOE harmonized model. The design report extends beyond this harmonized model to discuss some of the challenges with assessing algal production systems, including the ability to (1) quickly assess alternative algal production system designs, (2) assess spatial and temporal variability, and (3) perform large-scale assessments considering multiple scenarios for thousands of potential sites. The Algae Logistics Model (ALM) was developed to address each of these limitations of current modeling efforts to enable assessment of the economic feasibility of algal production systems across the United States. The (ALM) enables (1) dynamic assessments using spatiotemporal conditions, (2) exploration of algal production system design configurations, (3) investigation of algal production system operating assumptions, and (4) trade-off assessments with technology decisions and operating assumptions. The report discusses results from the ALM, which is used to assess the baseline design determined by harmonization efforts between U.S. DOE national laboratories. Productivity and resource assessment data is provided by coupling the ALM with the Biomass Assessment Tool developed at PNNL. This high-fidelity data is dynamically passed to the ALM and used to help better understand the impacts of spatial and temporal constraints on algal production systems by providing a cost for producing extracted algal lipids annually for each potential site.

  20. Development of AC and DC Power Supply Direct Interface Converter

    NASA Astrophysics Data System (ADS)

    Kato, Koji; Itoh, Jun-Ichi

    This paper proposes a novel control method for a direct interface converter for management of the energy flow in either an AC or DC supply. The proposed converter is constructed based on an indirect matrix converter. Therefore a proposed control strategy is based on an indirect control method with a triangular carrier wave. The basic operation of the proposed control method is confirmed by experimental results. In addition, this paper also proposes a commutation error compensation method of an output voltage error and an input current error for an indirect matrix converter. In the proposed method, the output voltage and input current error by the commutation can be compensated at the same time, because the PWM pulse of each switch is directly compensated. The validity of the proposed method is confirmed by experimental results. Those results prove that the proposed compensation method can decrease total harmonic distortion (THD) of the input and output current.

  1. Surface plasma wave assisted second harmonic generation of laser over a metal film

    SciTech Connect

    Chauhan, Santosh; Parashar, J.

    2015-01-15

    Second harmonic generation of laser mode converted surface plasma wave (SPW) over a corrugated metal film is studied. The laser, impinged on the metal film, under attenuated total reflection configuration, excites SPW over the metal–vacuum interface. The excited SPW extends over a much wider surface area than the laser spot cross-section. It exerts a second harmonic ponderomotive force on metal electrons, imparting them velocity that beats with the surface ripple to produce a nonlinear current, driving resonant second harmonic surface plasma wave.

  2. An Electronic Ballast Using Back-boost Converter

    NASA Astrophysics Data System (ADS)

    Yokozeki, I.; Kato, Y.; Kuratani, T.; Okamura, Y.; Ohkita, M.; Takahashi, N.

    The new circuit of the electronic ballast for a fluorescent lamp, which is based on the back-boost converter, is proposed. This circuit has the advantage further than the circuit that combined the converter for rectification with the inverter for lighting in some points. Those advantages are reduction of the number of elements and improvement in the circuit efficiency, etc. And this circuit also satisfies regulation value of IEC class C on the relative harmonic contents of input current. From experimental results, the effectiveness of the proposed circuit is shown.

  3. Comparison of Fine Structures of Electron Cyclotron Harmonic Emissions in Aurora

    NASA Astrophysics Data System (ADS)

    Labelle, J. W.; Dundek, M.

    2015-12-01

    Recent discoveries of emissions at four and five times the electron cyclotron frequency in aurora occuring under daylit conditions motivated the modification of radio receivers at South Pole Station, Antarctica, to measure fine structure of such emissions during two consecutive austral summers, 2013-4 and 2014-5. The experiment recorded 347 emission events over 376 days of observation. The seasonal distribution of these events revealed that successively higher harmonics require higher solar zenith angles for occurrence, as expected if they are generated at locations where the upper hybrid frequency matches the cyclotron harmonic, which for higher harmonics requires higher electron densities which are associated with higher solar zenith angles. Detailed examination of 21 cases in which two harmonics occur simultaneously showed that only rarely, about ten percent of the time, are the frequencies of the fine structures of the emissions in exact integer ratio (e.g., 3:2, 4:3, or 5:4 depending on which combination of harmonics is observed). In the remaining approximately ninety percent of the cases, the higher harmonic occurred at a lower ratio than the appropriate integer ratio, as expected if the harmonics are generated independently at their separate matching conditions in the bottomside ionosphere, where the upper hybrid frequency increases with altitude while the gyroharmonics decrease with altitude. (The bottomside is the most likely source of the emissions, since from there the mode converted Z-modes have access to ground-level.) Taken together, these results suggest that the dominant mechanism for the higher harmonics is independent generation at locations where the upper hybrid frequency matches each harmonic, i.e., at a separate source altitude for each harmonic. Generation of higher harmonics through coalescence of lower harmonic waves explains at most a small minority of events.

  4. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  5. Vector generator scan converter

    DOEpatents

    Moore, James M.; Leighton, James F.

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  6. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Goldstein, D. N.; Hirschkron, R.; Smith, C. E.

    1983-01-01

    Convertible propulsion systems for advanced rotorcraft are evaluated in terms of their impact on aircraft operating economics and fuel consumption. A variety of propulsion system concepts, including separate thrust and power producing engines, convertible fan/shaft engines, and auxiliary propeller configurations are presented. The merits of each are evaluated in two different rotorcraft missions: an intercity, commercial transport of the ABC(TM) type, and an offshore oil ring supply ship of the X-wing type. The variable inlet guide vane fan/shaft converting engine and auxiliary propeller configurations are shown to offer significant advantages over all the other systems evaluated, in terms of both direct operating cost and fuel consumption.

  7. Vector generator scan converter

    SciTech Connect

    Moore, J.M.; Leighton, J.F.

    1990-04-17

    This patent describes high printing speeds for graphics data that are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  8. Relativistic harmonic oscillator revisited

    SciTech Connect

    Bars, Itzhak

    2009-02-15

    The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

  9. Dynamic investigation of Drosophila myocytes with second harmonic generation microscopy

    NASA Astrophysics Data System (ADS)

    Greenhalgh, Catherine; Stewart, Bryan; Cisek, Richard; Prent, Nicole; Major, Arkady; Barzda, Virginijus

    2006-09-01

    The functional dynamics and structure of both larval and adult Drosophila melanogaster muscle were investigated with a nonlinear multimodal microscope. Imaging was carried out using a home built microscope capable of recording the multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation signals simultaneously at a scanning rate of up to ~12 frames/sec. The sample was excited by a home built femtosecond Ti:Sapphire laser at 840 nm, or by a Yb-ion doped potassium gadolinium tungstate (Yb:KGW) crystal based oscillator at 1042 nm. There was no observable damage detected in the myocyte after prolonged scanning with either of the lasers. Microscopic second harmonic generation (SHG) appears particularly strong in the myocytes. This allows the fast contraction dynamics of the myocytes to be followed. The larger sarcomere size observed in the larvae myocytes is especially well suited for studying the contraction dynamics. Microscopic imaging of muscle contractions showed different relaxation and contraction rates. The SHG intensities were significantly higher in the relaxed state of the myocyte compared to the contracted state. The imaging also revealed disappearance of SHG signal in highly stretched sarcomeres, indicating that SHG diminishes in the disordered structures. The study illustrates that SHG microscopy, combined with other nonlinear contrast mechanisms, can help to elucidate physiological mechanisms of contraction. This study also provides further insight into the mechanisms of harmonic generation in biological tissue and shows that crystalline arrangement of macromolecules has a determining factor for the high efficiency second harmonic generation from the bulk structures.

  10. Evading surface and detector frequency noise in harmonic oscillator measurements of force gradients

    NASA Astrophysics Data System (ADS)

    Moore, Eric W.; Lee, SangGap; Hickman, Steven A.; Harrell, Lee E.; Marohn, John A.

    2010-07-01

    We introduce and demonstrate a method of measuring small force gradients acting on a harmonic oscillator in which the force-gradient signal of interest is used to parametrically up-convert a forced oscillation below resonance into an amplitude signal at the oscillator's resonance frequency. The approach, which we demonstrate in a mechanically detected electron spin resonance experiment, allows the force-gradient signal to evade detector frequency noise by converting a slowly modulated frequency signal into an amplitude signal.

  11. Fractional Watt AMTEC Converter

    NASA Astrophysics Data System (ADS)

    Hunt, T. K.; Rasmussen, J. R.

    2006-01-01

    We report here the long term performance of a small, multi-tube AMTEC converter. This converter was designed to operate and produce approximately 12 watt of electrical output from a small, 4 to 6 watt radioisotope heat source for remote power applications. It was built and put on test in 1999 using electrical heaters as stand-ins for the radioisotope capsule. Since that time it has accumulated more than 5 years of run time at an input heater temperature of 700 °C, with numerous thermal cycles to ambient that were generally related to grid power failures or physical moves of the test apparatus. The power output has remained, with variations due to orientation changes and minor variations due to small temperature changes, essentially constant at 0.40 W to 0.60 W over the test period and operation is ongoing. The converter casing and mechanical structure was fabricated from 316 SS and the electrodes are sputtered titanium nitride films. Separate static tests of a multilayer insulation package suitable for use with the converter showed the capability to reach 700 °C with a thermal input of < 4 watts.

  12. Thermionic energy converters

    DOEpatents

    Monroe, Jr., James E.

    1977-08-09

    A thermionic device for converting nuclear energy into electrical energy comprising a tubular anode spaced from and surrounding a cylindrical cathode, the cathode having an outer emitting surface of ruthenium, and nuclear fuel on the inner cylindrical surface. The nuclear fuel is a ceramic composition of fissionable material in a metal matrix. An axial void is provided to collect and contain fission product gases.

  13. Echo-Enabled Harmonic Generation

    SciTech Connect

    Stupakov, Gennady; /SLAC

    2012-06-28

    A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.

  14. Echo-Enabled Harmonic Generation

    SciTech Connect

    Stupakov, Gennady

    2010-08-25

    A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.

  15. Liquid metal thermal electric converter

    DOEpatents

    Abbin, Joseph P.; Andraka, Charles E.; Lukens, Laurance L.; Moreno, James B.

    1989-01-01

    A liquid metal thermal electric converter which converts heat energy to electrical energy. The design of the liquid metal thermal electric converter incorporates a unique configuration which directs the metal fluid pressure to the outside of the tube which results in the structural loads in the tube to be compressive. A liquid metal thermal electric converter refluxing boiler with series connection of tubes and a multiple cell liquid metal thermal electric converter are also provided.

  16. Spherical harmonics in texture analysis

    NASA Astrophysics Data System (ADS)

    Schaeben, Helmut; van den Boogaart, K. Gerald

    2003-07-01

    The objective of this contribution is to emphasize the fundamental role of spherical harmonics in constructive approximation on the sphere in general and in texture analysis in particular. The specific purpose is to present some methods of texture analysis and pole-to-orientation probability density inversion in a unifying approach, i.e. to show that the classic harmonic method, the pole density component fit method initially introduced as a distinct alternative, and the spherical wavelet method for high-resolution texture analysis share a common mathematical basis provided by spherical harmonics. Since pole probability density functions and orientation probability density functions are probability density functions defined on the sphere Ω3⊂ R3 or hypersphere Ω4⊂ R4, respectively, they belong at least to the space of measurable and integrable functions L1( Ωd), d=3, 4, respectively. Therefore, first a basic and simplified method to derive real symmetrized spherical harmonics with the mathematical property of providing a representation of rotations or orientations, respectively, is presented. Then, standard orientation or pole probability density functions, respectively, are introduced by summation processes of harmonic series expansions of L1( Ωd) functions, thus avoiding resorting to intuition and heuristics. Eventually, it is shown how a rearrangement of the harmonics leads quite canonically to spherical wavelets, which provide a method for high-resolution texture analysis. This unified point of view clarifies how these methods, e.g. standard functions, apply to texture analysis of EBSD orientation measurements.

  17. Harmonic analysis of electrical distribution systems

    SciTech Connect

    1996-03-01

    This report presents data pertaining to research on harmonics of electric power distribution systems. Harmonic data is presented on RMS and average measurements for determination of harmonics in buildings; fluorescent ballast; variable frequency drive; georator geosine harmonic data; uninterruptible power supply; delta-wye transformer; westinghouse suresine; liebert datawave; and active injection mode filter data.

  18. Using the self-filtering property of a femtosecond filament to improve second harmonic generation.

    PubMed

    Shwa, David; Eisenmann, Shmuel; Marcus, Gilad; Zigler, Arie

    2009-04-13

    In this paper we demonstrate the use of NIR femtosecond filament for improving the generation of second harmonic using a type I BBO crystal. Using this method the beam propagation factor (M(2)) of the second harmonic was improved significantly; which led to enhancement of the attainable SH intensity by up to two orders of magnitude. This method can be beneficial for applications demanding high intensities, small spot size or long interaction lengths.

  19. Harmonics analysis of the photonic time stretch system.

    PubMed

    Mei, Yuan; Xu, Boyu; Chi, Hao; Jin, Tao; Zheng, Shilie; Jin, Xiaofeng; Zhang, Xianmin

    2016-09-10

    Photonic time stretch (PTS) has been intensively investigated in recent decades due to its potential application to ultra-wideband analog-to-digital conversion. A high-speed analog signal can be captured by an electronic analog-to-digital converter (ADC) with the help of the PTS technique, which slows down the speed of signal in the photonic domain. Unfortunately, the process of the time stretch is not linear due to the nonlinear modulation of the electro-optic intensity modulator in the PTS system, which means the undesired harmonics distortion. In this paper, we present an exact analytical model to fully characterize the harmonics generation in the PTS systems for the first time, to the best of our knowledge. We obtain concise and closed-form expressions for all harmonics of the PTS system with either a single-arm Mach-Zehnder modulator (MZM) or a push-pull MZM. The presented model can largely simplify the PTS system design and the system parameters estimation, such as system bandwidth, harmonics power, time-bandwidth product, and dynamic range. The correctness of the mathematic model is verified by the numerical and experimental results.

  20. Harmonics analysis of the photonic time stretch system.

    PubMed

    Mei, Yuan; Xu, Boyu; Chi, Hao; Jin, Tao; Zheng, Shilie; Jin, Xiaofeng; Zhang, Xianmin

    2016-09-10

    Photonic time stretch (PTS) has been intensively investigated in recent decades due to its potential application to ultra-wideband analog-to-digital conversion. A high-speed analog signal can be captured by an electronic analog-to-digital converter (ADC) with the help of the PTS technique, which slows down the speed of signal in the photonic domain. Unfortunately, the process of the time stretch is not linear due to the nonlinear modulation of the electro-optic intensity modulator in the PTS system, which means the undesired harmonics distortion. In this paper, we present an exact analytical model to fully characterize the harmonics generation in the PTS systems for the first time, to the best of our knowledge. We obtain concise and closed-form expressions for all harmonics of the PTS system with either a single-arm Mach-Zehnder modulator (MZM) or a push-pull MZM. The presented model can largely simplify the PTS system design and the system parameters estimation, such as system bandwidth, harmonics power, time-bandwidth product, and dynamic range. The correctness of the mathematic model is verified by the numerical and experimental results. PMID:27661356

  1. Digital to synchro converter

    NASA Technical Reports Server (NTRS)

    Predina, Joseph P. (Inventor)

    1989-01-01

    A digital-to-synchro converter is provided where a binary input code specifies a desired shaft angle and where an resolver type position transducer is employed with additional circuitry to generate a shaft position error signal indicative of the angular difference between the desired shaft angle and the actual shaft angle. The additional circuitry corrects for known and calculated errors in the shaft position detection process and equipment.

  2. Frequency Doubling Broadband Light in Multiple Crystals

    SciTech Connect

    ALFORD,WILLIAM J.; SMITH,ARLEE V.

    2000-07-26

    The authors compare frequency doubling of broadband light in a single nonlinear crystal with doubling in five crystals with intercrystal temporal walk off compensation, and with doubling in five crystals adjusted for offset phase matching frequencies. Using a plane-wave, dispersive numerical model of frequency doubling they study the bandwidth of the second harmonic and the conversion efficiency as functions of crystal length and fundamental irradiance. For low irradiance the offset phase matching arrangement has lower efficiency than a single crystal of the same total length but gives a broader second harmonic bandwidth. The walk off compensated arrangement gives both higher conversion efficiency and broader bandwidth than a single crystal. At high irradiance, both multicrystal arrangements improve on the single crystal efficiency while maintaining broad bandwidth.

  3. Content-based image classification with circular harmonic wavelets

    NASA Astrophysics Data System (ADS)

    Jacovitti, Giovanni; Neri, Alessandro

    1998-07-01

    Classification of an image on the basis of contained patterns is considered in a context of detection and estimation theory. To simplify mathematical derivations, image and reference patterns are represented on a complex support. This allows to convert the four positional parameters into two complex numbers: complex displacement and complex scale factor. The latter one represents isotropic dilations with its magnitude, and rotations with its phase. In this context, evaluation of the likelihood function under additive Gaussian noise assumption allows to relate basic template matching strategy to wavelet theory. It is shown that using circular harmonic wavelets simplifies the problem from a computational viewpoint. A general purpose pattern detection/estimation scheme is introduced by decomposing the images on a orthogonal basis formed by complex Laguerre-Gauss Harmonic wavelets.

  4. Multilevel converters -- A new breed of power converters

    SciTech Connect

    Lai, J.S.; Peng, F.Z. |

    1995-09-01

    Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc capacitor voltages. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The techniques to balance the voltage between different levels normally involve voltage clamping or capacitor charge control. There are several ways of implementing voltage balance in multilevel converters. Without considering the traditional magnetic coupled converters, this paper presents three recently developed multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded-inverters with separate dc sources. The operating principle, features, constraints, and potential applications of these converters will be discussed.

  5. Radiating dipoles in photonic crystals

    PubMed

    Busch; Vats; John; Sanders

    2000-09-01

    The radiation dynamics of a dipole antenna embedded in a photonic crystal are modeled by an initially excited harmonic oscillator coupled to a non-Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the photonic crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra are reproduced. This approach enables direct incorporation of realistic band structure computations into studies of radiative emission from atoms and molecules within photonic crystals. We therefore provide a predictive and interpretative tool for experiments in both the microwave and optical regimes.

  6. Transistorized converter provides nondissipative regulation

    NASA Technical Reports Server (NTRS)

    1964-01-01

    A transistorized regulator converter efficiently converts fluctuating input voltages to a constant output voltage, avoiding the use of saturable reactors. It is nondissipative in operation and functions in an open loop through variable duty cycles.

  7. Harmonic Nanoparticles for Regenerative Research

    PubMed Central

    Ronzoni, Flavio; Magouroux, Thibaud; Vernet, Remi; Extermann, Jérôme; Crotty, Darragh; Prina-Mello, Adriele; Ciepielewski, Daniel; Volkov, Yuri; Bonacina, Luigi; Wolf, Jean-Pierre; Jaconi, Marisa

    2014-01-01

    In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation nanoparticles (HNPs). The latter are a new family of probes recently introduced for labeling biological samples for multi-photon imaging. HNPs are capable of doubling the frequency of excitation light by the nonlinear optical process of second harmonic generation with no restriction on the excitation wavelength. Multi-photon based methodologies for hESC differentiation into cardiac clusters (maintained as long term air-liquid cultures) are presented in detail. In particular, evidence on how to maximize the intense second harmonic (SH) emission of isolated HNPs during 3D monitoring of beating cardiac tissue in 3D is shown. The analysis of the resulting images to retrieve 3D displacement patterns is also detailed. PMID:24836220

  8. Evaluation of harmonic suppression devices

    SciTech Connect

    Tolbert, L.M.; Hollis, H.D.; Hale, P.S. Jr.

    1996-09-01

    An assessment has been conducted of five commercially available devices to determine their ability to provide clean sinusoidal voltage to nonlinear loads and to eliminate harmonic currents demanded by nonlinear loads. The devices tested were a passive series-shunt filter, a delta-wye isolation transformer, a ferroresonant magnetic synthesizer, an active power line conditioner, and an active injection mode filter. These devices were installed in existing Department of Energy facilities that had substantial non-linear loads which drew a significant harmonic current. These devices were then compared in the following categories: cancellation of harmonic currents, supply of nondistorted voltage, supply of regulated voltage, elimination of transients and impulses, efficiency, reliability, and cost.

  9. Second-harmonic generation with Bessel beams

    NASA Astrophysics Data System (ADS)

    Shatrovoy, Oleg

    We present the results of a numerical simulation tool for modeling the second-harmonic generation (SHG) interaction experienced by a diffracting beam. This code is used to study the simultaneous frequency and spatial profile conversion of a truncated Bessel beam that closely resembles a higher-order mode (HOM) of an optical fiber. SHG with Bessel beams has been investigated in the past and was determined have limited value because it is less efficient than SHG with a Gaussian beam in the undepleted pump regime. This thesis considers, for the first time to the best of our knowledge, whether most of the power from a Bessel-like beam could be converted into a second-harmonic beam (full depletion), as is the case with a Gaussian beam. We study this problem because using HOMs for fiber lasers and amplifiers allows reduced optical intensities, which mitigates nonlinearities, and is one possible way to increase the available output powers of fiber laser systems. The chief disadvantage of using HOM fiber amplifiers is the spatial profile of the output, but this can be transformed as part of the SHG interaction, most notably to a quasi-Gaussian profile when the phase mismatch meets the noncollinear criteria. We predict, based on numerical simulation, that noncollinear SHG (NC-SHG) can simultaneously perform highly efficient (90%) wavelength conversion from 1064 nm to 532 nm, as well as concurrent mode transformation from a truncated Bessel beam to a Gaussian-like beam (94% overlap with a Gaussian) at modest input powers (250 W, peak power or continuous-wave operation). These simulated results reveal two attractive features -- the feasibility of efficiently converting HOMs of fibers into Gaussian-like beams, and the ability to simultaneously perform frequency conversion. Combining the high powers that are possible with HOM fiber amplifiers with access to non-traditional wavelengths may offer significant advantages over the state of the art for many important applications

  10. Converting amine concentrations

    SciTech Connect

    Carroll, J.J. )

    1994-03-01

    Aqueous solutions of alkanolamines are commonly used solvents and remove acid gas components from natural and synthesis gas. The literature is full of experimental data for these systems and examples of their application. One problem with comparing data from different sources is that different concentration units are used. A BASIC program was written to simplify the conversion process between these common concentration units: weight fraction or mass fraction, X, kg solute/kg solution; mole fraction, x, mol solute/mol solution; molarity, M, mol solute/l solution; and molarity, m, mol solute/kg solvent. A table lists the formulas for converting between these four units. The source code is included.

  11. The microminiature thermionic converter

    NASA Astrophysics Data System (ADS)

    King, Donald Bryan

    The design, fabrication, testing, and analysis of the microminiature thermionic converter (MTC) is discussed. MTCs are two electrode devices that convert heat energy into electrical energy. The electrodes are spaced opposite each other in a vacuum environment with one electrode heated and the second cooled. Electrons are emitted from the hot electrode to the cool electrode creating electrical power. The fabrication of the MTC uses micromachining and semiconductor integrated circuit fabrication methods. These fabrication techniques allow the MTC to have an inter-electrode spacing of 20 microns or less with electrode materials having work functions ranging from 0.75 to 3 eV. The small gap size and low work function features of the MTC give it the potential to produce electricity at relatively high conversion efficiencies (20--25%). MTC designs may be tailored to function for different heat sources (combustion, solar, advanced nuclear reactors, radioisotopes, waste heat) over broad temperature regimes. The MTC diode prototype has been successfully fabricated, operated, and analyzed over a wide range of emitter and collector temperatures in the power production mode as well as power consumption mode. The emitter temperatures of interest ranged from 770 through 1220K. Maximum power output densities of 2mW/cm2 have been produced, and maximum output voltages approaching 1 Volt have also been produced. The MTC has been used to power an external load consisting of a Motorola 1N4004 diode. Models have been developed to characterize thermionic surface emission and electron transport across the gap. The MTC diode current-voltage characteristics and features have been successfully modeled over all five operational modes that characterize a thermionic converter. Power production has not been as high as expected. The shortcomings are due to the low work function material, (Ba,Sr,Ca)O, used in the diode. The tests and models indicate that the irregularities in work function across

  12. Cycloidal Wave Energy Converter

    SciTech Connect

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  13. The harmonic frequencies of benzene

    NASA Astrophysics Data System (ADS)

    Handy, Nicholas C.; Maslen, Paul E.; Amos, Roger D.; Andrews, Jamie S.; Murray, Christopher W.; Laming, Gregory J.

    1992-09-01

    We report calculations for the harmonic frequencies of C 6H 6 and C 6D 6. Our most sophisticated quantum chemistry values are obtained with the MP2 method and a TZ2P+f basis set (288 basis functions), which are the largest such calculations reported on benzene to date. Using the SCF density, we also calculate the frequencies using the exchange and correlation expressions of density functional theory. We compare our calculated harmonic frequencies with those deduced from experiment by Goodman, Ozkabak and Thakur. The density functional frequencies appear to be more reliable predictions than the MP2 frequencies and they are obtained at significantly less cost.

  14. Analytic signals and harmonic measures

    NASA Astrophysics Data System (ADS)

    Qian, Tao

    2006-02-01

    We prove that a sufficient and necessary condition for Hei[Theta](s)=-iei[Theta](s), where H is Hilbert transformation, [Theta] is a continuous and strictly increasing function with [Theta](R)=2[pi], is that d[Theta](s) is a harmonic measure on the line. The counterpart result for the periodic case is also established. The study is motivated by, and has significant impact to time-frequency analysis, especially to aspects of analytic signals inducing instantaneous amplitude and frequency. As a by-product we introduce the theory of Hardy-space-preserving weighted trigonometric series and Fourier transformations induced by harmonic measures in the respective contexts.

  15. Radially polarized annular beam generated through a second-harmonic-generation process.

    PubMed

    Sato, Shunichi; Kozawa, Yuichi

    2009-10-15

    A radially polarized beam with an annular intensity pattern was generated through a second-harmonic-generation process by focusing an azimuthally polarized Ti:sapphire pulsed laser beam to a c-cut beta-barium borate (BBO) crystal. The annular intensity pattern of the second-harmonic wave had a nearly sixfold symmetry as a result of the nonlinear susceptibility tensor of the BBO crystal. The width of the annulus was as narrow as less than 1/40th of its radius.

  16. Planar second-harmonic generation with noncollinear pumps in disordered media.

    PubMed

    Roppo, Vito; Dumay, David; Trull, Jose; Cojocaru, Crina; Saltiel, Solomon M; Staliunas, Kestutis; Vilaseca, Ramon; Neshev, Dragomir N; Krolikowski, Wieslaw; Kivshar, Yuri S

    2008-09-01

    We study experimentally the process of the second harmonic generation by two noncollinear beams in quadratic nonlinear crystals with a disordered structure of ferroelectric domains. We show that the second-harmonic radiation is emitted in the form of two cones as well as in a plane representing the cross-correlation of the two fundamental pulses. We demonstrate the implementation of this parametric process for characterisation of femtosecond pulses, enabling the estimation of pulse width, chirp, and front tilt. This is achieved through monitoring the evolution of the autocorrelation trace inside the nonlinear crystal.

  17. A framework to analyze the stochastic harmonics and resonance of wind energy grid interconnection

    DOE PAGESBeta

    Cho, Youngho; Lee, Choongman; Hur, Kyeon; Kang, Yong Cheol; Muljadi, Eduard; Park, Sang -Ho; Choy, Young -Do; Yoon, Gi -Gab

    2016-08-31

    This study addresses a modeling and analysis methodology for investigating the stochastic harmonics and resonance concerns of wind power plants (WPPs). Wideband harmonics from modern wind turbines are observed to be stochastic, associated with real power production, and they may adversely interact with the grid impedance and cause unexpected harmonic resonance if not comprehensively addressed in the planning and commissioning of the WPPs. These issues should become more critical as wind penetration levels increase. We thus propose a planning study framework comprising the following functional steps: First, the best-fitted probability density functions (PDFs) of the harmonic components of interest inmore » the frequency domain are determined. In operations planning, maximum likelihood estimations followed by a chi-square test are used once field measurements or manufacturers' data are available. Second, harmonic currents from the WPP are represented by randomly-generating harmonic components based on their PDFs (frequency spectrum) and then synthesized for time-domain simulations via inverse Fourier transform. Finally, we conduct a comprehensive assessment by including the impacts of feeder configurations, harmonic filters, and the variability of parameters. We demonstrate the efficacy of the proposed study approach for a 100-MW offshore WPP consisting of 20 units of 5-MW full-converter turbines, a realistic benchmark system adapted from a WPP under development in Korea, and discuss lessons learned through this research.« less

  18. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  19. Bidirectional buck boost converter

    DOEpatents

    Esser, Albert Andreas Maria

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

  20. Bidirectional buck boost converter

    DOEpatents

    Esser, A.A.M.

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero. 20 figs.

  1. High-harmonic generation from an atomically thin semiconductor

    NASA Astrophysics Data System (ADS)

    Liu, Hanzhe; Li, Yilei; Ghimire, Shambhu; Heinz, Tony; Reis, David

    The process of high-harmonic generation (HHG) from ultrashort laser pulses has recently been observed in bulk solids, complementing the well-established process in the gas phase. HHG is of interest both as a source of ultrashort pulses in the attosecond regime that has photon energies extending up to the soft x-ray region and as a method of probing material response outside the regime of perturbative nonlinear optics. In this paper, we present the observation of HHG from a single atomic layer of MoS2 driven by a strong infrared pulse of 100 fs duration and 0.3 eV photon energy. We observe distinct harmonics up to the 13th order of the infrared excitation. The non-perturbative nature of the HHG process is demonstrated by the weak power dependence of the harmonic intensities. To gain further insight into the process, we have investigated the variation of the HHG signal with sample orientation and the ellipticity of pump excitation. We compare and contrast the process with that from the bulk MoS2 crystal. We find significant differences in the response for the monolayer and bulk crystal, which can be understood in terms of the distinct crystallographic symmetries in the two cases.

  2. Covariant harmonic oscillators: 1973 revisited

    NASA Technical Reports Server (NTRS)

    Noz, M. E.

    1993-01-01

    Using the relativistic harmonic oscillator, a physical basis is given to the phenomenological wave function of Yukawa which is covariant and normalizable. It is shown that this wave function can be interpreted in terms of the unitary irreducible representations of the Poincare group. The transformation properties of these covariant wave functions are also demonstrated.

  3. A novel modular approach to active power-line harmonic filtering in distribution systems

    NASA Astrophysics Data System (ADS)

    El Shatshat, Ramadan A.

    The objective of this research is to develop an efficient and reliable modular active harmonic filter system to realize a cost-effective solution to the harmonic problem. The proposed filter system consists of a number CSC modules, each dedicated to filter a specific harmonic of choice (Frequency-Splitting Approach). The power rating of the modules will decrease and their switching frequency will increase as the order of the harmonic to be filtered is increased. The overall switching losses are minimized due to the selected harmonic elimination and balanced a "power rating"-"switching frequency" product. Two ADALINEs are proposed as a part of the filter controller for processing the signals obtained from the power-line. One ADALINE (the Current ADALINE) extracts the fundamental and harmonic components of the distorted current. The other ADALINE (the Voltage ADALINE) estimates the line voltage. The outputs of both ADALINEs are used to construct the modulating signals of the filter modules. The proposed controller decides which CSC filter module(s) is connected to the electric grid. The automated connection of the corresponding filter module(s) is based on decision-making rules in such a way that the IEEE 519-1992 limits are not violated. The information available on the magnitude of each harmonic component allows us to select the active filter bandwidth (i.e., the highest harmonic to be suppressed). This will result in more efficiency and higher performance. The proposed controller adjusts the I dc in each CSC module according to the present magnitude of the corresponding harmonic current. This results in optimum dc-side current value and minimal converter losses. The comparison of the proposed modular active filter scheme and the conventional one converter scheme on practical use in industry is presented. This comparison shows that the proposed solution is more economical, reliable and flexible compared to conventional one. High speed and accuracy of ADALINE, self

  4. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  5. Unity power factor converter

    NASA Technical Reports Server (NTRS)

    Wester, Gene W. (Inventor)

    1980-01-01

    A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i.

  6. Harmonic Balance Computations of Fan Aeroelastic Stability

    NASA Technical Reports Server (NTRS)

    Bakhle, Milind A.; Reddy, T. S. R.

    2010-01-01

    A harmonic balance (HB) aeroelastic analysis, which has been recently developed, was used to determine the aeroelastic stability (flutter) characteristics of an experimental fan. To assess the numerical accuracy of this HB aeroelastic analysis, a time-domain aeroelastic analysis was also used to determine the aeroelastic stability characteristics of the same fan. Both of these three-dimensional analysis codes model the unsteady flowfield due to blade vibrations using the Reynolds-averaged Navier-Stokes (RANS) equations. In the HB analysis, the unsteady flow equations are converted to a HB form and solved using a pseudo-time marching method. In the time-domain analysis, the unsteady flow equations are solved using an implicit time-marching approach. Steady and unsteady computations for two vibration modes were carried out at two rotational speeds: 100 percent (design) and 70 percent (part-speed). The steady and unsteady results obtained from the two analysis methods compare well, thus verifying the recently developed HB aeroelastic analysis. Based on the results, the experimental fan was found to have no aeroelastic instability (flutter) at the conditions examined in this study.

  7. A harmonic analysis of lunar gravity

    NASA Astrophysics Data System (ADS)

    Bills, B. G.; Ferrari, A. J.

    1980-02-01

    An improved model of lunar global gravity has been obtained by fitting a sixteenth-degree harmonic series to a combination of Doppler tracking data from Apollo missions 8, 12, 15, and 16, and Lunar Orbiters 1, 2, 3, 4, and 5, and laser ranging data to the lunar surface. To compensate for the irregular selenographic distribution of these data, the solution algorithm has also incorporated a semi-empirical a priori covariance function. Maps of the free-air gravity disturbance and its formal error are presented, as are free-air anomaly and Bouguer anomaly maps. The lunar gravitational variance spectrum has the form V(G; n) = O(n to the -4th power), as do the corresponding terrestrial and martian spectra. The variance spectra of the Bouguer corrections (topography converted to equivalent gravity) for these bodies have the same basic form as the observed gravity; and, in fact, the spectral ratios are nearly constant throughout the observed spectral range for each body. Despite this spectral compatibility, the correlation between gravity and topography is generally quite poor on a global scale.

  8. Univalent harmonic mappings convex in one direction

    NASA Astrophysics Data System (ADS)

    Ponnusamy, S.; Kaliraj, A. Sairam

    2014-09-01

    In this paper, we present a criterion for a harmonic function to be convex in one direction. Also, we discuss the class of harmonic functions starlike in one direction in the unit disk and obtain a method to construct univalent harmonic functions convex in one direction. Although the converse of classical Alexander's theorem for harmonic functions was proved to be false, we obtain a version of converse of it under a suitable additional condition.

  9. Investigations on a hybrid positron source with a granular converter

    NASA Astrophysics Data System (ADS)

    Artru, X.; Chaikovska, I.; Chehab, R.; Chevallier, M.; Dadoun, O.; Furukawa, K.; Guler, H.; Kamitani, T.; Miyahara, F.; Satoh, M.; Sievers, P.; Suwada, T.; Umemori, K.; Variola, A.

    2015-07-01

    Promising results obtained with crystal targets for positron production led to the elaboration of a hybrid source made of an axially oriented tungsten crystal, as a radiator, and an amorphous tungsten converter. If the converter is granular, made of small spheres, the heat dissipation is greatly enhanced and the thermal shocks reduced, allowing the consideration of such device for the future linear colliders. A positron source of this kind is investigated. Previous simulations have shown very promising results for the yield as for the energy deposition and the PEDD (Peak Energy Deposition Density). Here, we present detailed simulations made in this granular converter with emphasis on the energy deposition density, which is a critical parameter as learned from the breakdown of the SLC target. A test on the KEKB linac is foreseen; it will allow a determination of the energy deposited and the PEDD in the converter through temperature measurements. Four granular converters, made of W spheres of mm radius have been built at LAL-Orsay; they will be installed at KEK and compared to compact converters. A description of the experimental layout at KEK is provided. Applications to future linear colliders as CLIC and ILC are considered.

  10. Turbo-Brayton Power Converter

    NASA Technical Reports Server (NTRS)

    Breedlove, Jeffrey

    2015-01-01

    Future NASA space missions will require advanced thermal-to-electric power converters that are reliable, efficient, and lightweight. Creare, LLC, is developing a turbo-Brayton power converter that offers high efficiency and specific power. The converter employs gas bearings to provide maintenance free, long-life operation. Discrete components can be packaged to fit optimally with other subsystems, and the converter's continuous gas flow can communicate directly with remote heat sources and heat rejection surfaces without the need for ancillary heat-transfer components and intermediate flow loops. Creare has completed detailed analyses, trade studies, fabrication trials, and preliminary designs for the components and converter assembly. The company is fabricating and testing a breadboard converter.

  11. Nanostructure Neutron Converter Layer Development

    NASA Technical Reports Server (NTRS)

    Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Kang, Jin Ho (Inventor); Lowther, Sharon E. (Inventor); Thibeault, Sheila A. (Inventor); Bryant, Robert G. (Inventor)

    2016-01-01

    Methods for making a neutron converter layer are provided. The various embodiment methods enable the formation of a single layer neutron converter material. The single layer neutron converter material formed according to the various embodiments may have a high neutron absorption cross section, tailored resistivity providing a good electric field penetration with submicron particles, and a high secondary electron emission coefficient. In an embodiment method a neutron converter layer may be formed by sequential supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In another embodiment method a neutron converter layer may be formed by simultaneous supercritical fluid metallization of a porous nanostructure aerogel or polyimide film. In a further embodiment method a neutron converter layer may be formed by in-situ metalized aerogel nanostructure development.

  12. Second-harmonic illumination to enhance multispectral digital lensless holographic microscopy.

    PubMed

    Mendoza-Yero, Omel; Carbonell-Leal, Miguel; Lancis, Jesús; Garcia-Sucerquia, Jorge

    2016-03-01

    Multispectral digital lensless holographic microscopy (MDLHM) operating with second-harmonic illumination is shown. Added to the improvement of the spatial resolution of the previously reported MDLHM operating with near-infrared illumination, this second-harmonic MDLHM shows promise as a tool to study the behavior of biological samples under a broad spectral illumination. This illumination is generated by focusing a highly spatially coherent ultrashort pulsed radiation into an uncoated Type 1 β-BaB2O4 (BBO) nonlinear crystal. The second-harmonic MDLHM allows achieving multispectral images of biological samples with enhanced micrometer spatial resolution. The illumination wavelength of the second-harmonic MDLHM can be tuned by displacing a focusing optics with respect to a pinhole; spatially resolved information at different wavelengths of the sample can then be retrieved.

  13. Resonant third harmonic generation of KrF laser in Ar gas

    SciTech Connect

    Rakowski, R.; Barna, A.; Suta, T.; Földes, I. B.; Bohus, J.; Szatmári, S.; Mikołajczyk, J.; Bartnik, A.; Fiedorowicz, H.; Verona, C.; Verona Rinati, G.; Margarone, D.; Nowak, T.; and others

    2014-12-15

    Investigations of emission of harmonics from argon gas jet irradiated by 700 fs, 5 mJ pulses from a KrF laser are presented. Harmonics conversion was optimized by varying the experimental geometry and the nozzle size. For the collection of the harmonic radiation silicon and solar-blind diamond semiconductor detectors equipped with charge preamplifiers were applied. The possibility of using a single-crystal CVD diamond detector for separate measurement of the 3rd harmonic in the presence of a strong pumping radiation was explored. Our experiments show that the earlier suggested 0.7% conversion efficiency can really be obtained, but only in the case when phase matching is optimized with an elongated gas target length corresponding to the length of coherence.

  14. Generation of ultra-intense gamma-ray train by QED harmonics

    NASA Astrophysics Data System (ADS)

    Liu, Chen; Shen, Baifei; Zhang, Xiaomei; Ji, Liangliang; Wang, Wenpeng; Xu, Jiancai; Zhao, Xueyan; Yi, Longqing; Shi, Yin; Zhang, Lingang; Xu, Tongjun; Pei, Zhikun; Xu, Zhizhan

    2016-08-01

    In nonlinear media, photons may combine into a photon of energy and momentum of all those photons. This process, called harmonic generation, happens in nonlinear crystal, gas, and relativistic plasma. When the laser intensity reaches 1022 W/cm2, QED effects appear and play a significant role in the harmonic generation. In contrast to the gas and relativistic high-order harmonic generation processes, harmonics influenced by QED effects are usually not coherent because of the characteristic of random radiation, while the property of high intensity and ultra-short duration is conserved. In this work, the generation of high-order harmonics with QED effects is investigated by one- and two-dimensional particle-in-cell simulations. Studies have shown that interacting with a laser pulse with the intensity of I =5.35 ×1023W /cm 2 , such harmonics can produce ultra-short gamma-ray train with periodic structures. The period of gamma-ray train is half of the laser period, and the peak intensity is 1.4 ×1022W /cm 2 from one-dimensional simulation when ions are considered immobile. This new harmonic production with QED effects are crucial to light-matter interaction in strong field and can be verified in experiments by 10 PW laser facilities in the near future.

  15. Harmon Craig (1926-2003)

    NASA Astrophysics Data System (ADS)

    Weiss, Ray

    Harmon Craig, one of the great pioneers of isotope geochemistry died on 14 March after suffering a massive heart attack at his home in La Jolla, California. He was one day shy of his 77th birthday. Through an academic career of more than fifty years, Craig—or simply “Harmon,” as he was known throughout the world of geochemistry—made a remarkable number of fundamental and far-reaching contributions in a wide range of important areas concerned with the chemical and physical processes by which the solid Earth, the oceans, the atmosphere, and the solar system interact. While his research was broad in scope, it was also characterized by a strong emphasis on meticulous field and laboratory work, and on original and insightful interpretations of the resulting observations.

  16. Dislocation Detection Through Harmonic Generation

    NASA Astrophysics Data System (ADS)

    Reinhardt, B. T.; Kropf, M.; Boudraeu, K.; Guers, M. J.; Tittmann, B. R.

    2010-02-01

    A fundamental goal of ultrasonic nondestructive evaluation is to characterize material defects before failure. During material fatigue, dislocations tend to nucleate, becoming sources of stress concentration. Eventually, cracks start to form and lead to material failure. Recent research has indicated that nonlinear harmonic generation can be used to distinguish between materials of high and low dislocation densities. This research reports nonlinear harmonic generation measurements to distinguish between those areas of high and low dislocation densities in copper bars. The copper bars were subjected to flexural fatigue. Periodic scans were taken in order to track dislocation development during the fatigue life of the material. We show that this technique provides improved early detection for critical components of failure.

  17. Self-powered microthermionic converter

    DOEpatents

    Marshall, Albert C.; King, Donald B.; Zavadil, Kevin R.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-08-10

    A self-powered microthermionic converter having an internal thermal power source integrated into the microthermionic converter. These converters can have high energy-conversion efficiencies over a range of operating temperatures. Microengineering techniques are used to manufacture the converter. The utilization of an internal thermal power source increases potential for mobility and incorporation into small devices. High energy efficiency is obtained by utilization of micron-scale interelectrode gap spacing. Alpha-particle emitting radioisotopes can be used for the internal thermal power source, such as curium and polonium isotopes.

  18. Harmonic ratcheting for fast acceleration

    NASA Astrophysics Data System (ADS)

    Cook, N.; Brennan, J. M.; Peggs, S.

    2014-04-01

    A major challenge in the design of rf cavities for the acceleration of medium-energy charged ions is the need to rapidly sweep the radio frequency over a large range. From low-power medical synchrotrons to high-power accelerator driven subcritical reactor systems, and from fixed focus alternating gradient accelerators to rapid cycling synchrotrons, there is a strong need for more efficient, and faster, acceleration of protons and light ions in the semirelativistic range of hundreds of MeV/u. A conventional way to achieve a large, rapid frequency sweep (perhaps over a range of a factor of 6) is to use custom-designed ferrite-loaded cavities. Ferrite rings enable the precise tuning of the resonant frequency of a cavity, through the control of the incremental permeability that is possible by introducing a pseudoconstant azimuthal magnetic field. However, rapid changes over large permeability ranges incur anomalous behavior such as the "Q-loss" and "f-dot" loss phenomena that limit performance while requiring high bias currents. Notwithstanding the incomplete understanding of these phenomena, they can be ameliorated by introducing a "harmonic ratcheting" acceleration scheme in which two or more rf cavities take turns accelerating the beam—one turns on when the other turns off, at different harmonics—so that the radio frequency can be constrained to remain in a smaller range. Harmonic ratcheting also has straightforward performance advantages, depending on the particular parameter set at hand. In some typical cases it is possible to halve the length of the cavities, or to double the effective gap voltage, or to double the repetition rate. This paper discusses and quantifies the advantages of harmonic ratcheting in general. Simulation results for the particular case of a rapid cycling medical synchrotron ratcheting from harmonic number 9 to 2 show that stability and performance criteria are met even when realistic engineering details are taken into consideration.

  19. Improving Density Functionals with Quantum Harmonic Oscillators

    NASA Astrophysics Data System (ADS)

    Tkatchenko, Alexandre

    2013-03-01

    Density functional theory (DFT) is the most widely used and successful approach for electronic structure calculations. However, one of the pressing challenges for DFT is developing efficient functionals that can accurately capture the omnipresent long-range electron correlations, which determine the structure and stability of many molecules and materials. Here we show that, under certain conditions, the problem of computing the long-range correlation energy of interacting electrons can be mapped to a system of coupled quantum harmonic oscillators (QHOs). The proposed model allows us to synergistically combine concepts from DFT, quantum chemistry, and the widely discussed random-phase approximation for the correlation energy. In the dipole limit, the interaction energy for a system of coupled QHOs can be calculated exactly, thereby leading to an efficient and accurate model for the many-body dispersion energy of complex molecules and materials. The studied examples include intermolecular binding energies, the conformational hierarchy of DNA structures, the geometry and stability of molecular crystals, and supramolecular host-guest complexes (A. Tkatchenko, R. A. DiStasio Jr., R. Car, M. Scheffler, Phys. Rev. Lett. 108, 236402 (2012); R. A. DiStasio Jr., A. von Lilienfeld, A. Tkatchenko, PNAS 109, 14791 (2012); A. Tkatchenko, D. Alfe, K. S. Kim, J. Chem. Theory and Comp. (2012), doi: 10.1021/ct300711r; A. Tkatchenko, A. Ambrosetti, R. A. DiStasio Jr., arXiv:1210.8343v1).

  20. Thyristor converter simulation and analysis

    SciTech Connect

    Zhang, S.Y.

    1991-01-01

    In this paper we present a simulation on thyristor converters. The simulation features nonlinearity, non-uniform firing, and the commutations. Several applications such as a current regulation, a converter frequency characteristics analysis, and a power line disturbance analysis will be presented. 4 refs., 4 figs.

  1. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  2. Multi-MW 22.8 GHz Harmonic Multiplier - RF Power Source for High-Gradient Accelerator R&D

    SciTech Connect

    Jay L. Hirshfield

    2012-07-26

    Electrodynamic and particle simulation studies have been carried out to optimize design of a two-cavity harmonic frequency multiplier, in which a linear electron beam is energized by rotating fields near cyclotron resonance in a TE111 cavity in a uniform magnetic field, and in which the beam then radiates coherently at the nth harmonic into a TEn11 output cavity. Examples are worked out in detail for 7th and 2nd harmonic converters, showing RF-to-RF conversion efficiencies of 45% and 88%, respectively at 19.992 GHz (K-band) and 5.712 GHz (C-band), for a drive frequency of 2.856 GHz. Details are shown of RF infrastructure (S-band klystron, modulator) and harmonic converter components (drive cavity, output cavities, electron beam source and modulator, beam collector) for the two harmonic converters to be tested. Details are also given for the two-frequency (S- and C-band) coherent multi-MW test stand for RF breakdown and RF gun studies.

  3. Improvement of Input Current Waveform for Soft-Switching Boost DCM Converter with Unity Power Factor

    NASA Astrophysics Data System (ADS)

    Taniguchi, Katsunori; Morizane, Toshimitsu; Kimura, Noriyuki

    In this paper, a soft-switching discontinuous mode (DCM) power factor corrected (PFC) converter is analyzed by applying the double Fourier series expansion. It is found that the fundamental component and higher-order harmonics included in the input current waveform are obtained by the Fourier series expansion of the mean value of the inductor current. From the theoretical analysis, a new method removing the distortion of the input current waveform is proposed. In spite of an open loop system, the proposed method makes a great improvement of the total harmonic distortion even if the ratio of output voltage to input voltage is very low.

  4. Symmetries of coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.

    1993-01-01

    It is shown that the system of two coupled harmonic oscillators possesses many interesting symmetries. It is noted that the symmetry of a single oscillator is that of the three-parameter group Sp(2). Thus two uncoupled oscillator exhibits a direct product of two Sp(2) groups, with six parameters. The coupling can be achieved through a rotation in the two-dimensional space of two oscillator coordinates. The closure of the commutation relations for the generators leads to the ten-parameter group Sp(4) which is locally isomorphic to the deSitter group O(3,2).

  5. Kolakoski sequence as an element to radiate giant forward and backward second harmonic signals

    SciTech Connect

    Parvini, T. S.; Tehranchi, M. M. E-mail: teranchi@sbu.ac.ir; Hamidi, S. M. E-mail: teranchi@sbu.ac.ir; Sarkarati, S.

    2015-11-14

    We propose a novel type of aperiodic one-dimensional photonic crystal structures which can be used for generating giant forward and backward second harmonic signals. The studied structure is formed by stacking together the air and nonlinear layers according to the Kolakoski self-generation scheme in which each nonlinear layer contains a pair of antiparallel 180° poled LiNbO{sub 3} crystal layers. For different generation stages of the structure, conversion efficiencies of forward and backward second harmonic waves have been calculated by nonlinear transfer matrix method. Numerical simulations show that conversion efficiencies in the Kolakoski-based multilayer are larger than the perfect ones for at least one order of magnitude. Especially for 33rd and 39th generation stages, forward second harmonic wave are 42 and 19 times larger, respectively. In this paper, we validate the strong fundamental field enhancement and localization within Kolakoski-based multilayer due to periodicity breaking which consequently leads to very strong radiation of backward and forward second harmonic signals. Following the applications of analogous aperiodic structures, we expect that Kolakosi-based multilayer can play a role in optical parametric devices such as multicolor second harmonic generators with high efficiency.

  6. High Resolution Switching Mode Inductance-to-Frequency Converter with Temperature Compensationti

    PubMed Central

    Matko, Vojko; Milanović, Miro

    2014-01-01

    This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal's natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85–100 μH to 2–560 kHz. PMID:25325334

  7. High resolution switching mode inductance-to-frequency converter with temperature compensation.

    PubMed

    Matko, Vojko; Milanović, Miro

    2014-10-16

    This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal's natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85-100 µH to 2-560 kHz.

  8. Thermoionic converter for space Reactor

    NASA Astrophysics Data System (ADS)

    Cao, Shengquan; Yang, Jicai

    1990-05-01

    Thermionic converters offer many advantages for use as space reactors. Over the last several years, six experiments were performed, of which four were in-pile experiments and two out-pile experiments. Of the four in-pile experiments, three involved the use of three converters linked in series. The use of nuclear reactors as the power source for an electrical system in space is one of the important developmental projects under consideration today. For a time extending relatively long into the future, according to most opinions on potential power requirements, the choice of a thermionic converter to implement thermoelectric conversion has many advantages.

  9. Killing vector fields and harmonic superfield theories

    SciTech Connect

    Groeger, Josua

    2014-09-15

    The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.

  10. Harmonic generation in magnetized quantum plasma

    NASA Astrophysics Data System (ADS)

    Kumar, Punit; Singh, Shiv; Singh, Abhisek Kumar

    2016-05-01

    A study of second harmonic generation by propagation of a linearly polarized electromagnetic wave through homogeneous high density quantum plasma in the presence of transverse magnetic field. The nonlinear current density and dispersion relations for the fundamental and second harmonic frequencies have been obtained using the recently developed quantum hydrodynamic (QHD) model. The effect of quantum Bohm potential, Fermi pressure and the electron spin have been taken into account. The second harmonic is found to be less dispersed than the first.

  11. Structural ordering and glass forming of soft spherical particles with harmonic repulsions

    SciTech Connect

    Sun, Bin; Sun, Zhiwei; Ouyang, Wenze Xu, Shenghua

    2014-04-07

    We carry out dissipative particle dynamics simulations to investigate the dynamic process of phase transformation in the system with harmonic repulsion particles. Just below the melting point, the system undergoes liquid state, face-centered cubic crystallization, body-centered cubic crystallization, and reentrant melting phase transition upon compression, which is in good agreement with the phase diagram constructed previously via thermodynamic integration. However, when the temperature is decreased sufficiently, the system is trapped into an amorphous and frustrated glass state in the region of intermediate density, where the solid phase and crystal structure should be thermodynamically most stable.

  12. A neural network model of harmonic detection

    NASA Astrophysics Data System (ADS)

    Lewis, Clifford F.

    2003-04-01

    Harmonic detection theories postulate that a virtual pitch is perceived when a sufficient number of harmonics is present. The harmonics need not be consecutive, but higher harmonics contribute less than lower harmonics [J. Raatgever and F. A. Bilsen, in Auditory Physiology and Perception, edited by Y. Cazals, K. Horner, and L. Demany (Pergamon, Oxford, 1992), pp. 215-222 M. K. McBeath and J. F. Wayand, Abstracts of the Psychonom. Soc. 3, 55 (1998)]. A neural network model is presented that has the potential to simulate this operation. Harmonics are first passed through a bank of rounded exponential filters with lateral inhibition. The results are used as inputs for an autoassociator neural network. The model is trained using harmonic data for symphonic musical instruments, in order to test whether it can self-organize by learning associations between co-occurring harmonics. It is shown that the trained model can complete the pattern for missing-fundamental sounds. The Performance of the model in harmonic detection will be compared with experimental results for humans.

  13. Resonantly-enhanced harmonic generation in Argon.

    PubMed

    Ackermann, P; Münch, H; Halfmann, T

    2012-06-18

    We present systematic investigations of harmonic generation in Argon, driven in the vicinity of a five-photon resonance by intense, tunable picosecond radiation pulses. When properly matching the laser frequency with the Stark-shifted multi-photon resonance, we observe a pronounced enhancement not only of the 5th, but also the 7th and 9th harmonic of the driving laser (i.e. at orders higher than the involved multi-photon resonance). We study the harmonic yield at different intensities and wavelengths of the driving laser to determine optimal conditions for resonantly-enhanced harmonic generation.

  14. Radiant energy to electric energy converter

    NASA Technical Reports Server (NTRS)

    Sher, Arden (Inventor)

    1980-01-01

    Radiant energy is converted into electric energy by irradiating a capacitor including an ionic dielectric. The dielectric is a sintered crystal superionic conductor, e.g., lanthanum trifluoride, lanthanum trichloride, or silver bromide, so that a multiplicity of crystallites exist between electrodes of the capacitor. The radiant energy cyclically irradiates the dielectric so that the dielectric exhibits a cyclic photocapacitive like effect. Adjacent crystallites have abutting surfaces that enable the crystallites to effectively form a multiplicity of series capacitor elements between the electrodes. Each of the capacitor elements has a dipole layer only on or near its surface. The capacitor is initially charged to a voltage just below the dielectric breakdown voltage by connecting it across a DC source causing a current to flow through a charging resistor to the dielectric. The device can be utilized as a radiant energy detector or as a solar energy cell.

  15. Nonlinear optical response of a two-dimensional atomic crystal.

    PubMed

    Merano, Michele

    2016-01-01

    The theory of Bloembergen and Pershan for the light waves at the boundary of nonlinear media is extended to a nonlinear two-dimensional (2D) atomic crystal, i.e., a single planar atomic lattice, placed between linear bulk media. The crystal is treated as a zero-thickness interface, a real 2D system. Harmonic waves emanate from it. Generalization of the laws of reflection and refraction give the direction and the intensity of the harmonic waves. As a particular case that contains all the essential physical features, second-order harmonic generation is considered. The theory, due to its simplicity that stems from the special character of a single planar atomic lattice, is able to elucidate and explain the rich experimental details of harmonic generation from a 2D atomic crystal.

  16. Wind/water energy converter

    NASA Technical Reports Server (NTRS)

    Paulkovich, J.

    1979-01-01

    Device will convert wind, water, tidal or wave energy into electrical or mechanical energy. Is comprised of windmill-like paddles or blades synchronously geared to orient themselves to wind direction for optimum energy extraction.

  17. Coherent Visible-Light-Generation Enhancement in Silicon-Based Nanoplasmonic Waveguides via Third-Harmonic Conversion.

    PubMed

    Sederberg, S; Elezzabi, A Y

    2015-06-01

    We report visible third-harmonic conversion at λ=517 nm in subwavelength silicon-based nanoplasmonic waveguides at an unprecedented conversion efficiency of 2.3×10^{-5}. This marks both the highest third-harmonic conversion efficiency in a silicon-based or nanoplasmonic structure and the smallest silicon waveguide structure demonstrated to date. The high conversion efficiency is attributed to tight electric field confinement and strong light-matter coupling arising from surface plasmon modes in the nanoplasmonic waveguide, enabling efficient nonlinear optical mixing over micrometer length scales. The nonresonant geometry of the waveguide enables the entire λ=1550 nm femtosecond pulse spectrum to be converted to its third harmonic, which may be easily extended to the entire visible spectrum. We envisage that third-harmonic generation in silicon-based nanoplasmonic waveguides could provide a platform for integrated, broadband visible light sources and entangled triplet photons on future hybrid electronic-silicon photonic chips.

  18. Transformerless dc-Isolated Converter

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E.

    1987-01-01

    Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

  19. Boron nitride converted carbon fiber

    DOEpatents

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  20. Three-dimensional nanostructures as highly efficient generators of second harmonic light.

    PubMed

    Zhang, Yu; Grady, Nathaniel K; Ayala-Orozco, Ciceron; Halas, Naomi J

    2011-12-14

    Plasmonic nanostructures enable the generation of large electromagnetic fields confined to small volumes, potentially providing a route for the development of nanoengineered nonlinear optical media. A metal-capped hemispherical nanoparticle, also known as a nanocup, generates second harmonic light with increasing intensity as the angle between the incident fundamental beam and the nanocup symmetry axis is increased. Nanoparticle orientation also modifies the emission direction of the second harmonic light. With conversion efficiencies similar to those of inorganic SHG crystals, these structures provide a promising approach for the design and fabrication of stable, synthetic second-order nonlinear optical materials tailored for specific wavelengths.

  1. Radiation effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2000-01-01

    DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

  2. Critical conditions of saddle-node bifurcations in switching DC-DC converters

    NASA Astrophysics Data System (ADS)

    Fang, Chung-Chieh

    2013-08-01

    Although existence of multiple periodic orbits in some DC-DC converters have been known for decades, linking the multiple periodic orbits with the saddle-node bifurcation (SNB) is rarely reported. The SNB occurs in popular DC-DC converters, but it is generally reported as a strange instability. Recently, design-oriented instability critical conditions are of great interest. In this article, average, sampled-data and harmonic balance analyses are applied and they lead to equivalent results. Many new critical conditions are derived. They facilitate future research on the instability associated with multiple periodic orbits, sudden voltage jumps or disappearances of periodic orbits observed in DC-DC converters. The effects of various converter parameters on the instability can be readily seen from the derived critical conditions. New Nyquist-like plots are also proposed to predict or prevent the occurrence of the instability.

  3. Optimum Design of LLC Resonant Converter using Inductance Ratio (Lm/Lr)

    NASA Astrophysics Data System (ADS)

    Palle, Kowstubha; Krishnaveni, K.; Ramesh Reddy, Kolli

    2016-07-01

    The main benefits of LLC resonant dc/dc converter over conventional series and parallel resonant converters are its light load regulation, less circulating currents, larger bandwidth for zero voltage switching, and less tuning of switching frequency for controlled output. An unique analytical tool, called fundamental harmonic approximation with peak gain adjustment is used for designing the converter. In this paper, an optimum design of the converter is proposed by considering three different design criterions with different values of inductance ratio (Lm/Lr) to achieve good efficiency at high input voltage. The optimum design includes the analysis in operating range, switching frequency range, primary side losses of a switch and stability. The analysis is carried out with simulation using the software tools like MATLAB and PSIM. The performance of the optimized design is demonstrated for a design specification of 12 V, 5 A output operating with an input voltage range of 300-400 V using FSFR 2100 IC of Texas instruments.

  4. A zero power harmonic transponder sensor for ubiquitous wireless μL liquid-volume monitoring.

    PubMed

    Huang, Haiyu; Chen, Pai-Yen; Hung, Cheng-Hsien; Gharpurey, Ranjit; Akinwande, Deji

    2016-01-01

    Autonomous liquid-volume monitoring is crucial in ubiquitous healthcare. However, conventional approach is based on either human visual observation or expensive detectors, which are costly for future pervasive monitoring. Here we introduce a novel approach based on passive harmonic transponder antenna sensor and frequency hopping spread spectrum (FHSS) pattern analysis, to provide a very low cost wireless μL-resolution liquid-volume monitoring without battery or digital circuits. In our conceptual demonstration, the harmonic transponder comprises of a passive nonlinear frequency multiplier connected to a metamaterial-inspired 3-D antenna designed to be highly sensitive to the liquid-volume within a confined region. The transponder first receives some FHSS signal from an interrogator, then converts such signal to its harmonic band and re-radiates through the antenna sensor. The harmonic signal is picked up by a sniffer receiver and decoded through pattern analysis of the high dimensional FHSS signal strength data. A robust, zero power, absolute accuracy wireless liquid-volume monitoring is realized in the presence of strong direct coupling, background scatters, distance variance as well as near-field human-body interference. The concepts of passive harmonic transponder sensor, metamaterial-inspired antenna sensor, and FHSS pattern analysis based sensor decoding may help establishing cost-effective, energy-efficient and intelligent wireless pervasive healthcare monitoring platforms. PMID:26732251

  5. A zero power harmonic transponder sensor for ubiquitous wireless μL liquid-volume monitoring.

    PubMed

    Huang, Haiyu; Chen, Pai-Yen; Hung, Cheng-Hsien; Gharpurey, Ranjit; Akinwande, Deji

    2016-01-01

    Autonomous liquid-volume monitoring is crucial in ubiquitous healthcare. However, conventional approach is based on either human visual observation or expensive detectors, which are costly for future pervasive monitoring. Here we introduce a novel approach based on passive harmonic transponder antenna sensor and frequency hopping spread spectrum (FHSS) pattern analysis, to provide a very low cost wireless μL-resolution liquid-volume monitoring without battery or digital circuits. In our conceptual demonstration, the harmonic transponder comprises of a passive nonlinear frequency multiplier connected to a metamaterial-inspired 3-D antenna designed to be highly sensitive to the liquid-volume within a confined region. The transponder first receives some FHSS signal from an interrogator, then converts such signal to its harmonic band and re-radiates through the antenna sensor. The harmonic signal is picked up by a sniffer receiver and decoded through pattern analysis of the high dimensional FHSS signal strength data. A robust, zero power, absolute accuracy wireless liquid-volume monitoring is realized in the presence of strong direct coupling, background scatters, distance variance as well as near-field human-body interference. The concepts of passive harmonic transponder sensor, metamaterial-inspired antenna sensor, and FHSS pattern analysis based sensor decoding may help establishing cost-effective, energy-efficient and intelligent wireless pervasive healthcare monitoring platforms.

  6. A zero power harmonic transponder sensor for ubiquitous wireless μL liquid-volume monitoring

    PubMed Central

    Huang, Haiyu; Chen, Pai-Yen; Hung, Cheng-Hsien; Gharpurey, Ranjit; Akinwande, Deji

    2016-01-01

    Autonomous liquid-volume monitoring is crucial in ubiquitous healthcare. However, conventional approach is based on either human visual observation or expensive detectors, which are costly for future pervasive monitoring. Here we introduce a novel approach based on passive harmonic transponder antenna sensor and frequency hopping spread spectrum (FHSS) pattern analysis, to provide a very low cost wireless μL-resolution liquid-volume monitoring without battery or digital circuits. In our conceptual demonstration, the harmonic transponder comprises of a passive nonlinear frequency multiplier connected to a metamaterial-inspired 3-D antenna designed to be highly sensitive to the liquid-volume within a confined region. The transponder first receives some FHSS signal from an interrogator, then converts such signal to its harmonic band and re-radiates through the antenna sensor. The harmonic signal is picked up by a sniffer receiver and decoded through pattern analysis of the high dimensional FHSS signal strength data. A robust, zero power, absolute accuracy wireless liquid-volume monitoring is realized in the presence of strong direct coupling, background scatters, distance variance as well as near-field human-body interference. The concepts of passive harmonic transponder sensor, metamaterial-inspired antenna sensor, and FHSS pattern analysis based sensor decoding may help establishing cost-effective, energy-efficient and intelligent wireless pervasive healthcare monitoring platforms. PMID:26732251

  7. A zero power harmonic transponder sensor for ubiquitous wireless μL liquid-volume monitoring

    NASA Astrophysics Data System (ADS)

    Huang, Haiyu; Chen, Pai-Yen; Hung, Cheng-Hsien; Gharpurey, Ranjit; Akinwande, Deji

    2016-01-01

    Autonomous liquid-volume monitoring is crucial in ubiquitous healthcare. However, conventional approach is based on either human visual observation or expensive detectors, which are costly for future pervasive monitoring. Here we introduce a novel approach based on passive harmonic transponder antenna sensor and frequency hopping spread spectrum (FHSS) pattern analysis, to provide a very low cost wireless μL-resolution liquid-volume monitoring without battery or digital circuits. In our conceptual demonstration, the harmonic transponder comprises of a passive nonlinear frequency multiplier connected to a metamaterial-inspired 3-D antenna designed to be highly sensitive to the liquid-volume within a confined region. The transponder first receives some FHSS signal from an interrogator, then converts such signal to its harmonic band and re-radiates through the antenna sensor. The harmonic signal is picked up by a sniffer receiver and decoded through pattern analysis of the high dimensional FHSS signal strength data. A robust, zero power, absolute accuracy wireless liquid-volume monitoring is realized in the presence of strong direct coupling, background scatters, distance variance as well as near-field human-body interference. The concepts of passive harmonic transponder sensor, metamaterial-inspired antenna sensor, and FHSS pattern analysis based sensor decoding may help establishing cost-effective, energy-efficient and intelligent wireless pervasive healthcare monitoring platforms.

  8. The harmonic organization of auditory cortex.

    PubMed

    Wang, Xiaoqin

    2013-01-01

    A fundamental structure of sounds encountered in the natural environment is the harmonicity. Harmonicity is an essential component of music found in all cultures. It is also a unique feature of vocal communication sounds such as human speech and animal vocalizations. Harmonics in sounds are produced by a variety of acoustic generators and reflectors in the natural environment, including vocal apparatuses of humans and animal species as well as music instruments of many types. We live in an acoustic world full of harmonicity. Given the widespread existence of the harmonicity in many aspects of the hearing environment, it is natural to expect that it be reflected in the evolution and development of the auditory systems of both humans and animals, in particular the auditory cortex. Recent neuroimaging and neurophysiology experiments have identified regions of non-primary auditory cortex in humans and non-human primates that have selective responses to harmonic pitches. Accumulating evidence has also shown that neurons in many regions of the auditory cortex exhibit characteristic responses to harmonically related frequencies beyond the range of pitch. Together, these findings suggest that a fundamental organizational principle of auditory cortex is based on the harmonicity. Such an organization likely plays an important role in music processing by the brain. It may also form the basis of the preference for particular classes of music and voice sounds. PMID:24381544

  9. Harmonic oscillator states in aberration optics

    NASA Technical Reports Server (NTRS)

    Wolf, Kurt Bernardo

    1993-01-01

    The states of the three-dimensional quantum harmonic oscillator classify optical aberrations of axis-symmetric systems due to the isomorphism between the two mathematical structures. Cartesian quanta and angular momentum classifications have their corresponding aberration classifications. The operation of concatenation of optical elements introduces a new operation between harmonic oscillator states.

  10. Sunspots and Their Simple Harmonic Motion

    ERIC Educational Resources Information Center

    Ribeiro, C. I.

    2013-01-01

    In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.

  11. Surface-Enhanced Second-Harmonic Generation

    SciTech Connect

    Chen, C. K.; de Castro, A. R.B.; Shen, Y. R.

    1981-01-12

    Second harmonic generation at a silver-air interface was enhanced due to surface roughness by a factor of 10⁴. The local field enhancement is believed to be responsible for the effect. An unusually broad luminescence background extending far beyond the antiStokes side of the second harmonic was also observed.

  12. Dynamics and control of instrumented harmonic drives

    NASA Technical Reports Server (NTRS)

    Kazerooni, H.; Ellis, S. R. (Principal Investigator)

    1995-01-01

    Since torque in harmonic drives is transmitted by a pure couple, harmonic drives do not generate radial forces and therefore can be instrumented with torque sensors without interference from radial forces. The installation of torque sensors on the stationary component of harmonic drives (the Flexipline cup in this research work) produce backdrivability needed for robotic and telerobotic compliant maneuvers. Backdrivability of a harmonic drive, when used as torque increaser, means that the output shaft can be rotated via finite amount of torque. A high ratio harmonic drive is non-backdrivable because its output shaft cannot be turned by applying a torque on it. This article first develops the dynamic behavior of a harmonic drive, in particular the non-backdrivability, in terms of a sensitivity transfer function. The instrumentation of the harmonic drive with torque sensor is then described. This leads to a description of the control architecture which allows modulation of the sensitivity transfer function within the limits established by the closed-loop stability. A set of experiments on an active hand controller, powered by a DC motor coupled to an instrumented harmonic drive, is given to exhibit this method's limitations.

  13. Hyperspherical harmonics with arbitrary arguments

    SciTech Connect

    Meremianin, A. V.

    2009-01-15

    The derivation scheme for hyperspherical harmonics (HSH) with arbitrary arguments is proposed. It is demonstrated that HSH can be presented as the product of HSH corresponding to spaces with lower dimensionality multiplied by the orthogonal (Jacobi or Gegenbauer) polynomial. The relation of HSH to quantum few-body problems is discussed. The explicit expressions for orthonormal HSH in spaces with dimensions from two to six are given. The important particular cases of four- and six-dimensional spaces are analyzed in detail and explicit expressions for HSH are given for several choices of hyperangles. In the six-dimensional space, HSH representing the kinetic-energy operator corresponding to (i) the three-body problem in physical space and (ii) four-body planar problem are derived.

  14. Hyperspherical harmonics with arbitrary arguments

    NASA Astrophysics Data System (ADS)

    Meremianin, A. V.

    2009-01-01

    The derivation scheme for hyperspherical harmonics (HSH) with arbitrary arguments is proposed. It is demonstrated that HSH can be presented as the product of HSH corresponding to spaces with lower dimensionality multiplied by the orthogonal (Jacobi or Gegenbauer) polynomial. The relation of HSH to quantum few-body problems is discussed. The explicit expressions for orthonormal HSH in spaces with dimensions from two to six are given. The important particular cases of four- and six-dimensional spaces are analyzed in detail and explicit expressions for HSH are given for several choices of hyperangles. In the six-dimensional space, HSH representing the kinetic-energy operator corresponding to (i) the three-body problem in physical space and (ii) four-body planar problem are derived.

  15. Point-based manifold harmonics.

    PubMed

    Liu, Yang; Prabhakaran, Balakrishnan; Guo, Xiaohu

    2012-10-01

    This paper proposes an algorithm to build a set of orthogonal Point-Based Manifold Harmonic Bases (PB-MHB) for spectral analysis over point-sampled manifold surfaces. To ensure that PB-MHB are orthogonal to each other, it is necessary to have symmetrizable discrete Laplace-Beltrami Operator (LBO) over the surfaces. Existing converging discrete LBO for point clouds, as proposed by Belkin et al., is not guaranteed to be symmetrizable. We build a new point-wisely discrete LBO over the point-sampled surface that is guaranteed to be symmetrizable, and prove its convergence. By solving the eigen problem related to the new operator, we define a set of orthogonal bases over the point cloud. Experiments show that the new operator is converging better than other symmetrizable discrete Laplacian operators (such as graph Laplacian) defined on point-sampled surfaces, and can provide orthogonal bases for further spectral geometric analysis and processing tasks.

  16. Electron cyclotron harmonic wave acceleration

    NASA Technical Reports Server (NTRS)

    Karimabadi, H.; Menyuk, C. R.; Sprangle, P.; Vlahos, L.

    1987-01-01

    A nonlinear analysis of particle acceleration in a finite bandwidth, obliquely propagating electromagnetic cyclotron wave is presented. It has been suggested by Sprangle and Vlahos in 1983 that the narrow bandwidth cyclotron radiation emitted by the unstable electron distribution inside a flaring solar loop can accelerate electrons outside the loop by the interaction of a monochromatic wave propagating along the ambient magnetic field with the ambient electrons. It is shown here that electrons gyrating and streaming along a uniform, static magnetic field can be accelerated by interacting with the fundamental or second harmonic of a monochromatic, obliquely propagating cyclotron wave. It is also shown that the acceleration is virtually unchanged when a wave with finite bandwidth is considered. This acceleration mechanism can explain the observed high-energy electrons in type III bursts.

  17. Quantum wormholes and harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Garay, Luis J.

    1993-01-01

    The quantum state of a wormhole can be represented by a path integral over all asymptotically Euclidean four-geometries and all matter fields which have prescribed values, the arguments of the wave function, on a three-surface which divides the space time manifold into two disconnected parts. Minisuperspace models which consist of a homogeneous massless scalar field coupled to a Friedmann-Robertson-Walker space time are considered. Once the path integral over the lapse function is performed, the requirement that the space time be asymptotically Euclidean can be accomplished by fixing the asymptotic gravitational momentum in the remaining path integral. It is argued that there does not exist any wave function which corresponds to asymptotic field configurations such that the effective gravitational constant is negative in the asymptotic region. Then, the wormhole wave functions can be written as linear combinations of harmonic oscillator wave functions.

  18. High order harmonic generation in rare gases

    SciTech Connect

    Budil, K.S.

    1994-05-01

    The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I {approximately}10{sup 13}-10{sup 14} W/cm{sup 2}) is focused into a dense ({approximately}10{sup l7} particles/cm{sup 3}) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic {open_quotes}source{close_quotes}. A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.

  19. Echo-Enabled Harmonic Generation for Seeded FELs

    SciTech Connect

    Stupakov, G.; /SLAC

    2011-05-19

    In the x-ray wavelengths, the two leading FEL concepts are the self-amplified spontaneous emission (SASE) configuration and the high-gain harmonic generation (HGHG) scheme. While the radiation from a SASE FEL is coherent transversely, it typically has rather limited temporal coherence. Alternatively, the HGHG scheme allows generation of fully coherent radiation by up-converting the frequency of a high-power seed laser. However, due to the relatively low up-frequency conversion efficiency, multiple stages of HGHG FEL are needed in order to generate x-rays from a UV laser. The up-frequency conversion efficiency can be greatly improved with the recently proposed echo-enabled harmonic generation (EEHG) technique. In this work we will present the concept of EEHG, and address some practically important issues that affect the performance of the seeding. We show how the EEHG can be incorporated in the FEL scheme and what is the expected performance of the EEHG seeded FEL. We will then briefly describe the first proof-of-principle EEHG experiment carried out at the Next Linear Collider Test Accelerator (NLCTA) at SLAC. We will also discuss latest advances in the echo-scheme approach, and refer to subsequent modifications of the original concept.

  20. Characterization of Second Harmonic Afterburner Radiation at the LCLS

    SciTech Connect

    Nuhn, Heinz-Dieter

    2010-09-14

    During commissioning of the Linac Coherent Light Source (LCLS) x-ray Free Electron Laser (FEL) at the SLAC National Accelerator Laboratory it was shown that saturation lengths much shorter than the installed length of the undulator line can routinely be achieved. This frees undulator segments that can be used to provide enhanced spectral properties and at the same time, test the concept of FEL Afterburners. In December 2009 a project was initiated to convert undulator segments at the down-beam end of the undulator line into Second Harmonic Afterburners (SHAB) to enhance LCLS radiation levels in the 10-20 keV energy range. This is being accomplished by replacement of gap-shims increasing the fixed gaps from 6.8 mm to 9.9 mm, which reduces their K values from 3.50 to 2.25 and makes the segments resonant at the second harmonic of the upstream unmodified undulators. This paper reports experimental results of the commissioning of the SHAB extension to LCLS.

  1. Crystal Creations.

    ERIC Educational Resources Information Center

    Whipple, Nona; Whitmore, Sherry

    1989-01-01

    Presents a many-faceted learning approach to the study of crystals. Provides instructions for performing activities including crystal growth and patterns, creating miniature simulations of crystal-containing rock formations, charcoal and sponge gardens, and snowflakes. (RT)

  2. Generation of multiplexed harmonics at interaction of multi-harmonic light beams in dielectric media with induced plasma

    NASA Astrophysics Data System (ADS)

    Stumpf, S. A.

    2015-12-01

    A significant number of papers investigate a propagation of intense two-color beam through air in conditions when inharmonic oscillations of valence electrons convert to a plasma nonlinearity. This paper extends the scope of analysis, examining more complex combinations of synchronized beams propagating through dielectric media: triple beam and a beam combined with quazi-static field. It is shown that adding a third harmonic to a mix of first and second ones does not show principal changes in interaction picture: all phenomena appear to be described well before. But adding a static field to an interaction scene shows new peculiarities in redistribution of pulse spectrum energy to infra-red wing of optical range.

  3. Effects of Analog-to-Digital Converter Nonlinearities on Radar Range-Doppler Maps

    SciTech Connect

    Doerry, Armin Walter; Dubbert, Dale F.; Tise, Bertice L.

    2014-07-01

    Radar operation, particularly Ground Moving Target Indicator (GMTI) radar modes, are very sensitive to anomalous effects of system nonlinearities. These throw off harmonic spurs that are sometimes detected as false alarms. One significant source of nonlinear behavior is the Analog to Digital Converter (ADC). One measure of its undesired nonlinearity is its Integral Nonlinearity (INL) specification. We examine in this report the relationship of INL to GMTI performance.

  4. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, T. R.; Lieb, D.; Oettinger, P. E.; Goodale, D. B.

    1977-01-01

    Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

  5. All-prism achromatic phase matching for tunable second-harmonic generation

    SciTech Connect

    Richman, Bruce A.; Bisson, Scott E.; Trebino, Rick; Jacobson, Alexander

    1999-05-01

    Achromatic phase matching (APM) involves dispersing the light entering a nonlinear optical crystal so that a wide range of wavelengths is simultaneously phase matched. We constructed an APM apparatus consisting of six prisms, the final dispersion angle of which was optimized to match to second order in wavelength the type I phase-matching angle of {beta} barium borate (BBO). With this apparatus, we doubled tunable fundamental light from 620 to 700 nm in wavelength using a 4-mm-long BBO crystal. An analogous set of six prisms after the BBO crystal, optimized to second order in second-harmonic wavelength, realigned the output second-harmonic beams. Computer simulations predict that adjustment of a single prism can compensate angular misalignment of any or all the prisms before the crystal, and similarly for the prisms after the crystal. We demonstrated such compensations with the experimental device. The simulations also indicate that the phase-matching wavelength band can be shifted and optimized for different crystal lengths. {copyright} 1999 Optical Society of America

  6. All-prism achromatic phase matching for tunable second-harmonic generation.

    PubMed

    Richman, B A; Bisson, S E; Trebino, R; Sidick, E; Jacobson, A

    1999-05-20

    Achromatic phase matching (APM) involves dispersing the light entering a nonlinear optical crystal so that a wide range of wavelengths is simultaneously phase matched. We constructed an APM apparatus consisting of six prisms, the final dispersion angle of which was optimized to match to second order in wavelength the type I phase-matching angle of beta barium borate (BBO). With this apparatus, we doubled tunable fundamental light from 620 to 700 nm in wavelength using a 4-mm-long BBO crystal. An analogous set of six prisms after the BBO crystal, optimized to second order in second-harmonic wavelength, realigned the output second-harmonic beams. Computer simulations predict that adjustment of a single prism can compensate angular misalignment of any or all the prisms before the crystal, and similarly for the prisms after the crystal. We demonstrated such compensation with the experimental device. The simulations also indicate that the phase-matching wavelength band can be shifted and optimized for different crystal lengths.

  7. A high-fidelity harmonic drive model.

    SciTech Connect

    Preissner, C.; Royston, T. J.; Shu, D.

    2012-01-01

    In this paper, a new model of the harmonic drive transmission is presented. The purpose of this work is to better understand the transmission hysteresis behavior while constructing a new type of comprehensive harmonic drive model. The four dominant aspects of harmonic drive behavior - nonlinear viscous friction, nonlinear stiffness, hysteresis, and kinematic error - are all included in the model. The harmonic drive is taken to be a black box, and a dynamometer is used to observe the input/output relations of the transmission. This phenomenological approach does not require any specific knowledge of the internal kinematics. In a novel application, the Maxwell resistive-capacitor hysteresis model is applied to the harmonic drive. In this model, sets of linear stiffness elements in series with Coulomb friction elements are arranged in parallel to capture the hysteresis behavior of the transmission. The causal hysteresis model is combined with nonlinear viscous friction and spectral kinematic error models to accurately represent the harmonic drive behavior. Empirical measurements are presented to quantify all four aspects of the transmission behavior. These measurements motivate the formulation of the complete model. Simulation results are then compared to additional measurements of the harmonic drive performance.

  8. Asymptotic porosity of planar harmonic measure

    NASA Astrophysics Data System (ADS)

    Graczyk, Jacek; Świaţek, Grzegorz

    2013-04-01

    We study the distribution of harmonic measure on connected Julia sets of unicritical polynomials. Harmonic measure on a full compact set in ℂ is always concentrated on a set which is porous for a positive density of scales. We prove that there is a topologically generic set {A} in the boundary of the Mandelbrot set such that for every cin {A}, β>0, and λ∈(0,1), the corresponding Julia set is a full compact set with harmonic measure concentrated on a set which is not β-porous in scale λ n for n from a set with positive density amongst natural numbers.

  9. Harmonics generated from a DC biased transformer

    SciTech Connect

    Shu Lu; Yilu Liu; Ree, J. De La . The Bradley Dept. of Electrical Engineering)

    1993-04-01

    The paper presents harmonic characteristics of transformer excitation currents under DC bias caused by geomagnetically induced currents (GIC). A newly developed saturation model of a single phase shell form transformer based on 3D finite element analysis is used to calculate the excitation currents. As a consequence, the complete variations of excitation current harmonics with respect to an extended range of GIC bias are revealed. The results of this study are useful in understanding transformers as harmonic sources and the impact on power systems during a solar magnetic disturbance.

  10. Charge-pump voltage converter

    DOEpatents

    Brainard, John P.; Christenson, Todd R.

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  11. Converting Work into College Credits

    ERIC Educational Resources Information Center

    Hoffman, Joseph A.

    1976-01-01

    The Cooperative Education Program conducted by the New Jersey Department of Labor and Industry and Thomas A. Edison College enables State labor department employees to work toward college degrees by attending free classes, taking college-level examinations for college credit, and converting work and life experiences into college credits.…

  12. FM-to-Digital Converter

    NASA Technical Reports Server (NTRS)

    Moniuszko, Michael

    1987-01-01

    Circuit includes array of low-cost multivibrators. Inexpensive circuit converts frequency-modulated (FM) signal into digital signal. Consists of zero-crossing detector and series of monostable multivibrators and D-type flip-flops. Used to control filter.

  13. An oscillator circuit for dual-harmonic tracking of frequency and resistance in quartz resonator sensors

    NASA Astrophysics Data System (ADS)

    Ferrari, Marco; Ferrari, Vittorio

    2009-12-01

    An oscillator circuit is proposed that simultaneously excites and tracks two harmonic resonances in a quartz crystal resonator sensor. The oscillator outputs two pairs of signals, related to the sensor series resonant frequency and motional resistance for the fundamental and the third harmonic, respectively. The circuit also provides compensation of the sensor parallel capacitance for increased accuracy. By probing the resonator with the superposition of two harmonic modes simultaneously, enhanced sensing capabilities can be advantageously achieved because a larger set of parameters can be measured with a single sensor and its response is tracked in real time. Experimental tests were first run with the developed oscillator connected to 5 MHz AT-cut crystals exposed to different liquid solutions, obtaining results in good agreement with the theory. Evidence of different dynamic responses at the fundamental and the third harmonic was obtained, possibly related to differences in acoustic penetration depth into the liquid. The oscillator was then tested with the sensor loaded by microdroplets of liquid solutions deposited by a piezoelectric microdispenser. The oscillator could detect and track the resulting time response of the sensor, outperforming measurement methods based on impedance analysis in terms of speed and resolution, and evidencing a complex combination of effects in the sensor transient response.

  14. Multilevel converters for power system applications

    SciTech Connect

    Lai, J.S.; Stovall, J.P.; Peng, F.Z. |

    1995-09-01

    Multilevel converters are emerging as a new breed of power converter options for power system applications. These converters are most suitable for high voltage high power applications because they connect devices in series without the need for component matching. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. To avoid voltage unbalance between different levels, several techniques have been proposed for different applications. Excluding magnetic-coupled converters, this paper introduces three multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded inverters with separate dc sources. The operation principle, features, constraints, and potential applications of these converters will be discussed.

  15. Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Bache, M.; Bang, O.; Zhou, B. B.; Moses, J.; Wise, F. W.

    2010-12-01

    We show through theory and numerics that when few-cycle femtosecond solitons are generated through cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov radiation in the form of linear dispersive waves located in the red part of the spectrum. The beating between the dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering around the dispersive wave peak results in near-transform-limited ultrashort mid-IR pulses with pulse durations much shorter than the input near-IR pulse. The Cherenkov radiation for the crystal considered (β-barium borate) is found for pump wavelengths in the range λ=0.95-1.45μm, and is located in the regime λ=1.5-3.5μm. For shorter pump wavelengths, the phase-matching point is located in the absorption region of the crystal, effectively absorbing the generated dispersive wave. By calculating the phase-matching curves for typically used frequency conversion crystals, we point out that the mid-IR absorption in the crystal in many cases automatically will filter away the dispersive wave. Finally, an investigation of recent experimental results uncovers a four-wave-mixing phenomenon related to Cherenkov radiation that is an additional generation mechanism of long-wavelength radiation that can occur during soliton compression. We discuss the conditions that lead to this alternative dynamics rather than generation of Cherenkov radiation.

  16. Dot patterns from second-harmonic and sum-frequency generation in polycrystalline ZnSe

    NASA Astrophysics Data System (ADS)

    Chinh, Tran Duc; Seibt, Wolfgang; Siegbahn, Kai

    2001-09-01

    During a comparative study of second-harmonic generation (SHG) and sum-frequency generation (SFG) in single-crystal and polycrystalline ZnSe, the polycrystalline material showed a dot pattern in the SHG as well as in the SFG output. No such pattern was found in the output from the single-crystal ZnSe sample. The second-harmonic and also the sum-frequency dot pattern, resembling a diffraction pattern, could be observed over a wide tuning range of the fundamental beam, between 1.1 and 1.6 μm, generated by a femtosecond optical parametric amplifier. The size of the observed pattern is dependent on wavelength and the dots show a characteristic polarization.

  17. Spectral behavior of second harmonic signals from organic and non-organic materials in multiphoton microscopy

    PubMed Central

    Ehmke, Tobias; Knebl, Andreas; Reiss, Stephan; Fischinger, Isaak R.; Seiler, Theo G.; Stachs, Oliver; Heisterkamp, Alexander

    2015-01-01

    Multimodal nonlinear microscopy allows imaging of highly ordered biological tissue due to spectral separation of nonlinear signals. This requires certain knowledge about the spectral distribution of the different nonlinear signals. In contrast to several publications we demonstrate a factor of 122 relating the full width at half maximum of a gaussian laser pulse spectrum to the corresponding second harmonic pulse spectrum in the spatial domain by using a simple theoretical model. Experiments on monopotassium phosphate crystals (KDP-crystals) and on porcine corneal tissue support our theoretical predictions. Furthermore, no differences in spectral width were found for epi- and trans-detection of the second harmonic signal. Overall, these results may help to build an optimized multiphoton setup for spectral separation of nonlinear signals. PMID:26339527

  18. Spectral behavior of second harmonic signals from organic and non-organic materials in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Ehmke, Tobias; Knebl, Andreas; Reiss, Stephan; Fischinger, Isaak R.; Seiler, Theo G.; Stachs, Oliver; Heisterkamp, Alexander

    2015-08-01

    Multimodal nonlinear microscopy allows imaging of highly ordered biological tissue due to spectral separation of nonlinear signals. This requires certain knowledge about the spectral distribution of the different nonlinear signals. In contrast to several publications we demonstrate a factor of /1 2 √{ 2 } relating the full width at half maximum of a gaussian laser pulse spectrum to the corresponding second harmonic pulse spectrum in the spatial domain by using a simple theoretical model. Experiments on monopotassium phosphate crystals (KDP-crystals) and on porcine corneal tissue support our theoretical predictions. Furthermore, no differences in spectral width were found for epi- and trans-detection of the second harmonic signal. Overall, these results may help to build an optimized multiphoton setup for spectral separation of nonlinear signals.

  19. Second-harmonic generation efficiency for multifrequency ytterbium-doped fibre laser radiation

    SciTech Connect

    Politko, M O; Kablukov, S I; Nemov, I N; Babin, Sergei A

    2013-02-28

    The second-harmonic generation (SHG) efficiency for cw Yb-doped fibre laser radiation, which is characterised by many longitudinal modes with random phases, is compared with the SHG efficiency for amplified single-frequency Nd : YAG laser radiation in ppLN and KTP crystals, characterised by the type-I and type-IIphase matching, respectively. It is shown that the conversion efficiency into the second harmonic in the multifrequency regime for both crystals is higher by a factor of about 1.6, a value close to the calculated enhancement (2 for the Gaussian mode statistics). This difference is explained by possible deviation of the statistics of the Yb-doped fibre laser radiation from Gaussian, which is confirmed by measurements of the laser temporal dynamics. (laser optics 2012)

  20. Density- and wavefunction-normalized Cartesian spherical harmonics for l ≤ 20

    DOE PAGESBeta

    Michael, J. Robert; Volkov, Anatoliy

    2015-03-01

    The widely used pseudoatom formalism in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ≤ 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens. It was shown that the analytical form for normalization coefficients is available primarily forl ≤ 4. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 < l ≤ 7.more » In most cases for l > 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle–Coppens method in the Wolfram Mathematicasoftware to derive the Cartesian spherical harmonics for l ≤ 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.« less

  1. Density- and wavefunction-normalized Cartesian spherical harmonics for l ≤ 20

    SciTech Connect

    Michael, J. Robert; Volkov, Anatoliy

    2015-03-01

    The widely used pseudoatom formalism in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ≤ 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens. It was shown that the analytical form for normalization coefficients is available primarily forl ≤ 4. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 < l ≤ 7. In most cases for l > 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle–Coppens method in the Wolfram Mathematicasoftware to derive the Cartesian spherical harmonics for l ≤ 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.

  2. Parametric study of laser photovoltaic energy converters

    NASA Technical Reports Server (NTRS)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  3. The International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR) - A Pathway for Harmonization.

    PubMed

    Myers, Gary L; Miller, W Greg

    2016-02-01

    Results from clinical laboratory measurement procedures must be equivalent to enable effective use of clinical guidelines for disease diagnosis and patient management. Analytical results that are harmonized and independent of the measurement system, time, and location of testing is essential for providing adequate patient care. The key to generating harmonized results is establishing traceability to an accepted reference standard where available. Awareness of the benefits of having traceable measurement results that are harmonized has increased along with efforts to develop approaches to enable and facilitate the implementation of harmonization. Although several organizations are addressing harmonization of test procedures, centralized and cooperative global oversight is needed to ensure that the most important tests are being addressed and resources are optimally used. Working with its domestic and international partners, the American Association for Clinical Chemistry (AACC) has created an International Consortium for Harmonization of Clinical Laboratory Results. Advances in this area will improve the quality of patient care. PMID:27683504

  4. The International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR) – A Pathway for Harmonization

    PubMed Central

    Miller, W. Greg

    2016-01-01

    Results from clinical laboratory measurement procedures must be equivalent to enable effective use of clinical guidelines for disease diagnosis and patient management. Analytical results that are harmonized and independent of the measurement system, time, and location of testing is essential for providing adequate patient care. The key to generating harmonized results is establishing traceability to an accepted reference standard where available. Awareness of the benefits of having traceable measurement results that are harmonized has increased along with efforts to develop approaches to enable and facilitate the implementation of harmonization. Although several organizations are addressing harmonization of test procedures, centralized and cooperative global oversight is needed to ensure that the most important tests are being addressed and resources are optimally used. Working with its domestic and international partners, the American Association for Clinical Chemistry (AACC) has created an International Consortium for Harmonization of Clinical Laboratory Results. Advances in this area will improve the quality of patient care. PMID:27683504

  5. The International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR) – A Pathway for Harmonization

    PubMed Central

    Miller, W. Greg

    2016-01-01

    Results from clinical laboratory measurement procedures must be equivalent to enable effective use of clinical guidelines for disease diagnosis and patient management. Analytical results that are harmonized and independent of the measurement system, time, and location of testing is essential for providing adequate patient care. The key to generating harmonized results is establishing traceability to an accepted reference standard where available. Awareness of the benefits of having traceable measurement results that are harmonized has increased along with efforts to develop approaches to enable and facilitate the implementation of harmonization. Although several organizations are addressing harmonization of test procedures, centralized and cooperative global oversight is needed to ensure that the most important tests are being addressed and resources are optimally used. Working with its domestic and international partners, the American Association for Clinical Chemistry (AACC) has created an International Consortium for Harmonization of Clinical Laboratory Results. Advances in this area will improve the quality of patient care.

  6. Semiclassical approaches to below-threshold harmonics

    SciTech Connect

    Hostetter, James A.; Tate, Jennifer L.; Schafer, Kenneth J.; Gaarde, Mette B.

    2010-08-15

    We study the generation of below-threshold harmonics in a model atom by extending the three-step semiclassical model of harmonic generation to include effects of the atomic potential. We explore the generalization of semiclassical trajectories of the electron in the presence of the combined laser-atom potential and calculate the intensity-dependent dipole phase associated with these trajectories. Our results are in good agreement with fully quantum mechanical calculations, as well as with recent experimental observations. We show that the so-called long trajectory readily generalizes to below-threshold harmonic generation and is relatively insensitive to the choice of initial conditions. We also find that the short trajectory can only lead to low-energy harmonics for electrons that have been released close to the ion core in a process that is closer to multiphoton than to tunnel ionization.

  7. High-harmonic generation in cavitated plasmas

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Comier-Michel, E.; Leemans, W. P.

    2008-05-15

    A method is proposed for producing coherent x-rays via high-harmonic generation using ultraintense lasers interacting with highly stripped ions in cavitated plasmas. This method relies on plasma cavitation by the wake of an intense drive beam (laser or electron beam) to produce an ion cavity. An ultrashort pulse laser propagating in the plasma-electron-free ion cavity generates laser harmonics. The longitudinal electron motion, which inhibits high-harmonic generation at high laser intensities, can be suppressed by the space-charge field in the ion cavity or by using a counterpropagating laser pulse. Periodic suppression of the longitudinal electron motion may also be used to quasi-phase-match. This method enables harmonic generation to be extended to the sub-A regime.

  8. Geomagnetic local and regional harmonic analyses.

    USGS Publications Warehouse

    Alldredge, L.R.

    1982-01-01

    Procedures are developed for using rectangular and cylindrical harmonic analyses in local and regional areas. Both the linear least squares analysis, applicable when component data are available, and the nonlinear least squares analysis, applicable when only total field data are available, are treated. When component data are available, it is advantageous to work with residual fields obtained by subtracting components derived from a harmonic potential from the observed components. When only total field intensity data are available, they must be used directly. Residual values cannot be used. Cylindrical harmonic analyses are indicated when fields tend toward cylindrical symmetry; otherwise, rectangular harmonic analyses will be more advantageous. Examples illustrating each type of analysis are given.-Author

  9. New ladder operators for the monopole harmonics

    SciTech Connect

    Fakhri, H.; Dehghani, A.; Jafari, A.

    2007-02-15

    Using the ladder operators shifting the index m of the associated Jacobi functions, for a given n, the monopole harmonics and their corresponding angular momentum operators are, respectively, extracted as the irreducible representation space and generators of su(2) Lie algebra. The indices n and m play the role of principal and azimuthal quantum numbers. By introducing the ladder operators shifting the index n of the same associated Jacobi functions, we also get a new type of the raising and lowering relations which are realized by the operators shifting only the index n of the monopole harmonics. Moreover, other symmetries, including the transformation of the irreducible representation spaces into each other, are derived based on the operators that shift the indices n and m of the monopole harmonics simultaneously and agreeably as well as simultaneously and inversely. Our results are reduced to spherical harmonics by eliminating magnetic charge of the monopole.

  10. Multisite EPR Oximetry from Multiple Quadrature Harmonics

    PubMed Central

    Ahmad, R.; Som, S.; Johnson, D.H.; Zweier, J.L.; Kuppusamy, P.; Potter, L.C.

    2011-01-01

    Multisite continuous wave (CW) electron paramagnetic resonance (EPR) oximetry using multiple quadrature field modulation harmonics is presented. First, a recently developed digital receiver is used to extract multiple harmonics of field modulated projection data. Second, a forward model is presented that relates the projection data to unknown parameters, including linewidth at each site. Third, a maximum likelihood estimator of unknown parameters is reported using an iterative algorithm capable of jointly processing multiple quadrature harmonics. The data modeling and processing are applicable for parametric lineshapes under nonsaturating conditions. Joint processing of multiple harmonics leads to 2-3 fold acceleration of EPR data acquisition. For demonstration in two spatial dimensions, both simulations and phantom studies on an L-band system are reported. PMID:22154283

  11. SEVENTH HARMONIC 20 GHz CO-GENERATOR

    SciTech Connect

    Hirshfield, Jay L

    2014-04-08

    To satisfy the need for multi-MW rf sources in frequency ranges where commercial sources do not exist, a study was undertaken on a class of devices based on gyro-harmonic frequency multiplication. This mechanism relies upon adding energy in gyrating motion to a linear electron beam that traverses a rotating-mode TE111-mode drive cavity in a dc magnetic field. The beam then drifts along the magnetic field into a second cavity, operating in the TEn11-mode tuned to the nth harmonic of the drive cavity. Studies of this configuration have been carried out for 2 < n < 7. Results are given for multi-MW, efficient operation of a 7th harmonic device operating at 20 GHz, and a 2nd harmonic device operating at 22.4 GHz.

  12. Harmonic Lasing Characterization at Jefferson Lab

    SciTech Connect

    Stephen Benson; Michelle D. Shinn

    2006-08-27

    Harmonic lasing is normally suppressed because of lasing at the fundamental wavelength. It can, however, be achieved by using any of several methods that suppress fundamental lasing. In this paper we discuss two methods used at Jefferson Lab. The first is to use the characteristics of dielectric coatings to allow harmonic lasing at cavity lengths longer than the synchronous length for the fundamental. The second is to use a dielectric coating that has little reflectivity at the fundamental. This allows us to directly compare fundamental and harmonic lasing with the same optical resonator and electron beam. We present measurement carried out at Jefferson Lab using the IR Upgrade FEL operating at 0.53, 0.94, 1.04, 1.6, and 2.8 microns in which both schemes are used to produce lasing at both the 3rd and 5th harmonic of the fundamental.

  13. Second harmonic generation in periodically poled lithium niobate waveguide using femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Shuanggen; Yao, Jianghong; Fan, Yaxian; Liu, Weiwei; Liu, Yange; Shi, Qing; Huang, Zhangchao; Lu, Fuyun

    2008-11-01

    We present in this paper the fabrication and characterization of thermally stable double line waveguides in Z-cut periodically poled Lithium Niobate crystals. The waveguides were fabricated by using a femto-second laser, and utilized for second-harmonic generation. Our experiments have shown that a quasi-phase matching wavelength of 1548.2 nm, a tuning bandwidth of 2 nm, and a tuning temperature range of 150.4+/-1.6°C can be achieved.

  14. Second harmonic generation in a low-loss orientation-patterned GaAs waveguide.

    PubMed

    Fedorova, K A; McRobbie, A D; Sokolovskii, G S; Schunemann, P G; Rafailov, E U

    2013-07-15

    The technology of low-loss orientation-patterned gallium arsenide (OP-GaAs) waveguided crystals was developed and realized by reduction of diffraction scattering on the waveguide pattern. The propagation losses in the OP-GaAs waveguide were estimated to be as low as 2.1 dB/cm, thus demonstrating the efficient second harmonic generation at 1621 nm under an external pumping.

  15. Spectral characterization of some second harmonic generation materials from the amino acid family: L-Threonine and L-prolinium tartrate

    NASA Astrophysics Data System (ADS)

    Moovendaran, K.; Natarajan, S.

    2014-08-01

    Single crystals of the organic non-linear optical materials L-threonine (I) and L-prolinium tartrate (II) were grown using a home-made crystal growth setup (MKN setup). The grown crystals were characterized using X-ray diffraction, Infrared (IR), UV-vis-NIR and Circular dichroism (CD) spectroscopy. Measurements of Vicker’s microhardness, laser damage threshold (LDT) values and second harmonic generation (SHG) efficiencies are reported. Thermal and dielectric studies were also carried out.

  16. Transplantation: To convert or not to convert: lessons from the CONVERT trial.

    PubMed

    Bunnapradist, Suphamai; Vincenti, Flavio

    2009-07-01

    In participants of the CONVERT trial, which enrolled recipients of kidney transplants, conversion of immunosuppressive therapy from calcineurin inhibitors to sirolimus did not improve renal function. More importantly, the intervention was detrimental among patients with impaired kidney function and/or proteinuria. Sirolimus conversion resulted, however, in lower rates of malignancy.

  17. Measuring Spherical Harmonic Coefficients on a Sphere

    SciTech Connect

    Pollaine, S; Haan, S W

    2003-05-16

    The eigenfunctions of Rayleigh-Taylor modes on a spherical capsule are the spherical harmonics Y{sub l,m} These can be measured by measuring the surface perturbations along great circles and fitting them to the first few modes by a procedure described in this article. For higher mode numbers, it is more convenient to average the Fourier power spectra along the great circles, and then transform them to spherical harmonic modes by an algorithm derived here.

  18. HARMONIC CAVITY PERFORMANCE FOR NSLS-II

    SciTech Connect

    BLEDNYKH, A.; KRINSKY, S.; PODOBEDOV, B.; ROSE, J.; TOWNE, N.; WANG, J.M.

    2005-05-15

    NSLS-II is a 3 GeV ultra-high brightness storage ring planned to succeed the present NSLS rings at BNL. Ultralow emittance combined with short bunch length means that it is critical to minimize the effects of Touschek scattering and coherent instabilities. Improved lifetime and stability can be achieved by including a third-harmonic RF cavity in the baseline design. This paper describes the required harmonic RF parameters and the expected system performance.

  19. The Case of the Missing Harmonic Structure

    SciTech Connect

    Arp, U.

    2007-01-19

    Classical synchrotron radiation theory predicts emission in harmonics of the revolution frequency of the radiating particles. The Synchrotron Ultraviolet Radiation Facility SURF is an electron storage ring based on the weak focusing principle. The particles travel on a near perfect circular path, which makes SURF an ideal test-bed for synchrotron radiation theory. The harmonic structure of the radiation emitted by the electrons stored in SURF will be explored.

  20. Harmonic plane wave propagation in gyroelectric media

    NASA Astrophysics Data System (ADS)

    Hillion, Pierre

    2006-05-01

    We analyse the behaviour of harmonic plane waves in unbounded gyroelectric media once the refractive index in the direction of propagation is known from the Fresnel equation. We get, for the electric and magnetic fields, analytical expressions simple enough to use in a plane wave spectrum representation of more structured electromagnetic fields in these media. We also discuss the reflection and refraction of harmonic plane waves at the boundary between an isotropic medium and a gyroelectric material.

  1. Quantum harmonic oscillator with superoscillating initial datum

    SciTech Connect

    Buniy, R. V.; Struppa, D. C.; Colombo, F.; Sabadini, I.

    2014-11-15

    In this paper, we study the evolution of superoscillating initial data for the quantum driven harmonic oscillator. Our main result shows that superoscillations are amplified by the harmonic potential and that the analytic solution develops a singularity in finite time. We also show that for a large class of solutions of the Schrödinger equation, superoscillating behavior at any given time implies superoscillating behavior at any other time.

  2. Higher-Order Harmonic Generation from Fullerene by Means of the Plasma Harmonic Method

    SciTech Connect

    Ganeev, R. A.; Bom, L. B. Elouga; Abdul-Hadi, J.; Ozaki, T.; Wong, M. C. H.; Brichta, J. P.; Bhardwaj, V. R.

    2009-01-09

    We demonstrate, for the first time, high-order harmonic generation from C{sub 60} by an intense femtosecond Ti:sapphire laser. Laser-produced plasmas from C{sub 60}-rich epoxy and C{sub 60} films were used as the nonlinear media. Harmonics up to the 19th order were observed. The harmonic yield from fullerene-rich plasma is about 25 times larger compared with those produced from a bulk carbon target. Structural studies of plasma debris confirm the presence and integrity of fullerenes within the plasma plume, indicating fullerenes as the source of high-order harmonics.

  3. Second-harmonic generation in zinc tris(thiourea) sulfate

    SciTech Connect

    Marcy, H.O.; Warren, L.F. ); Webb, M.S.; Ebbers, C.A.; Velsko, S.P. ); Kennedy, G.C.; Catella, G.C. )

    1992-08-20

    The linear and second-order nonlinear optical properties of single-crystal zinc tris(thiourea) sulfate, or ZTS, are determined. The deduced nonlinear coefficients are {vert bar} {ital d}{sub 31} {vert bar}=0.31, {vert bar} {ital d}{sub 32} {vert bar}=0.35, and {vert bar} {ital d}{sub 33} {vert bar}=0.23 pm/V compared with a {vert bar} {ital d}{sub 14} {vert bar} value of 0.39 pm/V for potassium dihydrogen phosphate. Because it exhibits a low angular sensitivity ({delta}{Delta}{ital k}/{delta}{theta}), ZTS may prove useful for type-II second-harmonic generation from 1.06 to 1.027 {mu}m. We present the phase-matching measurement data for ZTS and compare the calculated frequency conversion efficiency for ZTS with that of several other well-characterized materials.

  4. Automatic recognition of harmonic bird sounds

    NASA Astrophysics Data System (ADS)

    Heller, Jason R.; Pinezich, John D.

    2005-09-01

    The method of sound recognition relies on a transformation of a sound into a spectrogram followed by extraction of the harmonics as curves. The extracted curves are called frequency tracks. A procedure called find-feasible-sets is used to extract sets of tracks that may correspond to harmonic sounds. If a set of tracks overlap each other sufficiently in time, then the set is designated a feasible set. Following the extraction of the feasible sets, the procedure find-maximal-subsets is applied to each feasible set. This procedure uses a function called harmonic-relate that determines if two tracks are harmonically related. All tracks that are not harmonically related to any other tracks in the feasible set are discarded. Furthermore, the feasible set is divided into maximal subsets. A maximal subset is a subset of the feasible set in which every track is harmonically related to one fixed track in the set called the reference track but no other tracks in the feasible set are related to the reference track. Each frequency track in a track set is transformed into a feature vector whose components describe the frequency, slope, and shape of the track. The species of birds analyzed are bluejay and herring gull.

  5. Evaluating harmonic-induced transformer heating

    SciTech Connect

    Bishop, M.T.; Baranowski, J.F.; Heath, D.; Benna, S.J.

    1996-01-01

    The proliferation of non-linear loads on power systems has increased the awareness of the potential reduction of a transformer`s life due to increased losses. Over the past few years, several manufacturers and users have been applying a harmonic rating system to specify transformers based on relationships developed in ANSI/IEEE C57.110. The specification or evaluation of transformers in a harmonic environment requires a knowledge of the load mix as well as details of the load current harmonic content. The additional heating experienced by a transformer depends on the harmonic content of the load current, and the design of the unit. A heat run circuit was devised to produce harmonic rich load current on a 25 kVA oil-immersed distribution transformer. The test was conducted at 100% of nameplate current using a purely resistive load, and a 2.4 ms current pulse. The temperature rise experienced under harmonic excitation was observed and documented.

  6. Harmonic Oscillators as Bridges between Theories

    SciTech Connect

    Kim, Y.S.; Noz, Marilyn E.

    2005-03-31

    Other than scattering problems where perturbation theory is applicable, there are basically two ways to solve problems in physics. One is to reduce the problem to harmonic oscillators, and the other is to formulate the problem in terms of two-by-two matrices. If two oscillators are coupled, the problem combines both two-by-two matrices and harmonic oscillators. This method then becomes a powerful research tool to cover many different branches of physics. Indeed, the concept and methodology in one branch of physics can be translated into another through the common mathematical formalism. It is noted that the present form of quantum mechanics is largely a physics of harmonic oscillators. Special relativity is the physics of the Lorentz group which can be represented by the group of by two-by-two matrices commonly called SL(2, c). Thus the coupled harmonic oscillators can therefore play the role of combining quantum mechanics with special relativity. Both Paul A. M. Dirac and Richard P. Feynman were fond of harmonic oscillators, while they used different approaches to physical problems. Both were also keenly interested in making quantum mechanics compatible with special relativity. It is shown that the coupled harmonic oscillators can bridge these two different approaches to physics.

  7. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L.J.; DeYoreo, J.J.; Roberts, D.H.

    1992-03-24

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light. 12 figs.

  8. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L. Jeffrey; DeYoreo, James J.; Roberts, David H.

    1992-01-01

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light.

  9. Generation of tunable ultrafast ultraviolet third harmonic by collinear compensation of group-velocity mismatch

    NASA Astrophysics Data System (ADS)

    Meng, Xianghao; Liu, Huagang; Huang, Jianhong; Wu, Hongchun; Deng, Jing; Dai, Shutao; Weng, Wen; Lin, Wenxiong

    2015-10-01

    We demonstrate a high efficient frequency tripling configuration of Ti: sapphire amplifier system for wavelength-tunable ultrafast ultraviolet laser generation. A new nonlinear crystal Ba1-xB2-y-zO4SixAlyGaz and a type-II phase-matched β-BaB2O4 crystal are employed for the second and the third harmonic generation, respectively. Significant improvement in conversion efficiency of frequency tripling is achieved by using a 65°-cut, 3-mm-long β-BaB2O4 crystal as the collinear group velocity compensation plate. Tunable ultraviolet pulse within the wavelength range from 256.7 to 276.7 nm have been produced, with a maximum average power of 212 mW, corresponding to a conversion efficiency of 8.48% for the third harmonic generation with 2.5 W fundamental power. The maximum pulse energy of the third harmonic is up to 0.21 mJ and it is estimated that the peak power is above 1 GW at 266.7 nm.

  10. 2. LOOKING NORTH ON COMMERCE ST. SHOWING HARMON MATTRESS FACTORY. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. LOOKING NORTH ON COMMERCE ST. SHOWING HARMON MATTRESS FACTORY. BRIDGE CONNECTS HARMON MATTRESS FACTORY WITH HARMON WAREHOUSE (SEE PHOTO HABS WA-165-15). BUILDING IN LEFT FOREGROUND IS LINDSTROM-BERG CABINET FACTORY (SEE PHOTO HABS WA-165-36). - Union Depot Area Study, F. S. Harmon Mattress Company, 1953 South C Street, Tacoma, Pierce County, WA

  11. Dual aperture dipole magnet with second harmonic component

    DOEpatents

    Praeg, Walter F.

    1985-01-01

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  12. Dual aperture dipole magnet with second harmonic component

    DOEpatents

    Praeg, W.F.

    1983-08-31

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  13. UCN Production With a Single Crystal of Ortho-Deuterium.

    PubMed

    Utsuro, M; Tanaka, M; Mishima, K; Nagai, Y; Shima, T; Fukuda, Y; Kohmoto, T; Momose, T; Moriai, A; Okumura, K; Yoshino, H

    2005-01-01

    The present paper reports on the preliminary experimental results concerning a new concept of ultracold neutron production with a single crystal converter of ortho-deuterium lying in the ground rotational state at the low temperature of about 10 K, which should make it possible to utilize a guided cold neutron beam instead of irradiating the converter material in the inside of high radiation fields. The successful observation of the clear Bragg scattering pattern from the single crystal converter and the reasonable results from the first experimental trial of the ultracold neutron production with the single crystal are shown.

  14. Photoelectric converters with quantum coherence.

    PubMed

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency η_{CA}. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to η_{CA} through manipulation of carefully controlled quantum coherences. PMID:27300826

  15. Photoelectric converters with quantum coherence

    NASA Astrophysics Data System (ADS)

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency ηCA. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to ηCA through manipulation of carefully controlled quantum coherences.

  16. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler, Lisle B.; Kokko, Edwin; Switzer, Vernon A

    2007-05-22

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  17. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler,; Lisle B.; Kokko, Edwin; Switzer, Vernon A

    2010-10-26

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  18. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W.; Hollaway, Rocky; Henning, Carl D.; Deteresa, Steve; Grundler, Walter; Hagler, Lisle B.; Kokko, Edwin; Switzer, Vernon A.

    2011-03-15

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.

  19. Photoelectric converters with quantum coherence.

    PubMed

    Su, Shan-He; Sun, Chang-Pu; Li, Sheng-Wen; Chen, Jin-Can

    2016-05-01

    Photon impingement is capable of liberating electrons in electronic devices and driving the electron flux from the lower chemical potential to higher chemical potential. Previous studies hinted that the thermodynamic efficiency of a nanosized photoelectric converter at maximum power is bounded by the Curzon-Ahlborn efficiency η_{CA}. In this study, we apply quantum effects to design a photoelectric converter based on a three-level quantum dot (QD) interacting with fermionic baths and photons. We show that, by adopting a pair of suitable degenerate states, quantum coherences induced by the couplings of QDs to sunlight and fermion baths can coexist steadily in nanoelectronic systems. Our analysis indicates that the efficiency at maximum power is no longer limited to η_{CA} through manipulation of carefully controlled quantum coherences.

  20. Status of advanced bremsstrahlung converters

    SciTech Connect

    Halbleib, J.A.

    1980-01-01

    This paper is an attempt to review the somewhat ill-defined area of advanced converter research in a more or less chronological fashion. Section 2 reviews the early B/sub z/ work that was motivated by the CASINO project. More recent work makes liberal use of technology from ICF research using REBs is discussed in Sec. 3. Section 4 discusses possible directions for future research, some of which are being actively pursued at Sandia National Laboratories (SNL) and elsewhere.

  1. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, D. P.; Oettinger, P. E.

    1976-01-01

    The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

  2. The harmonic oscillator and the position dependent mass Schroedinger equation: isospectral partners and factorization operators

    SciTech Connect

    Morales, J.; Ovando, G.; Pena, J. J.

    2010-12-23

    One of the most important scientific contributions of Professor Marcos Moshinsky has been his study on the harmonic oscillator in quantum theory vis a vis the standard Schroedinger equation with constant mass [1]. However, a simple description of the motion of a particle interacting with an external environment such as happen in compositionally graded alloys consist of replacing the mass by the so-called effective mass that is in general variable and dependent on position. Therefore, honoring in memoriam Marcos Moshinsky, in this work we consider the position-dependent mass Schrodinger equations (PDMSE) for the harmonic oscillator potential model as former potential as well as with equi-spaced spectrum solutions, i.e. harmonic oscillator isospectral partners. To that purpose, the point canonical transformation method to convert a general second order differential equation (DE), of Sturm-Liouville type, into a Schroedinger-like standard equation is applied to the PDMSE. In that case, the former potential associated to the PDMSE and the potential involved in the Schroedinger-like standard equation are related through a Riccati-type relationship that includes the equivalent of the Witten superpotential to determine the exactly solvable positions-dependent mass distribution (PDMD)m(x). Even though the proposed approach is exemplified with the harmonic oscillator potential, the procedure is general and can be straightforwardly applied to other DEs.

  3. Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

    PubMed

    Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

    2014-05-01

    Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. PMID:24531108

  4. A mathematical model of the class D converter for compact fluorescent ballasts

    SciTech Connect

    Nerone, L.R.

    1995-11-01

    The time-harmonic analysis is often used to design the class D converter. Since the Q of the resonant network is often low, this analysis, in the form of the sinusoidal approximation, begins to lose accuracy. This paper explores an improved method of designing compact fluorescent ballasts via the square wave approximation (SWA), where the time domain equations are solved for the general case of arbitrary Q, duty ratio, and frequency. A precise mathematical model of the Class D converter is developed that predicts the currents and voltages of the converter and these solutions are compared with computer simulation. Nonlinear programming (NLP) is introduced as a means to design the ballast for the lowest conduction losses. The equations developed in the mathematical model are formulated into a NLP format that includes the self-oscillating case.

  5. Zigzag Connected Autotransformer-Based 24-pulse AC-DC Converter

    NASA Astrophysics Data System (ADS)

    Xiao-qiang, Chen; Hao, Qiu

    2015-02-01

    In this paper, a zigzag connected autotransformer-based 24-pulse AC-DC converter is designed, modeled and simulated to feed direct torque controlled induction motor drives. Winding arrangements and parameters of the autotransformer and interphase reactor are given. Moreover, the design procedure of the autotransformer is modified to make it suitable for retrofit applications. Simulation results indicate that the system is capable of eliminating up to 21st harmonics in the ac mains current. The effect of load variation and load character is also studied to demonstrate the performance and effectiveness of the proposed 24-pulse converters. A set of power quality indices at ac mains and dc side are presented to compare the performance of 6-, 12- and 24-pulse converters.

  6. Human Lung Angiotensin Converting Enzyme

    PubMed Central

    Friedland, Joan; Silverstein, Emanuel; Drooker, Martin; Setton, Charlotte

    1981-01-01

    To enable its immunohistologic localization, angiotensin converting enzyme (EC 3.4.15.1) from human lung was solubilized by trypsinization and purified ∼2,660-fold to apparent homogeneity from a washed lung particulate fraction. The specific activity of pure enzyme was estimated to be 117 μmol/min per mg protein with the substrate hippuryl-l-histidyl-l-leucine. Consistent with previously described lung enzyme studies, catalytic activity was strongly inhibited by EDTA, O-phenanthroline, SQ 20,881, and SQ 14,225 and increased by CoCl2. SQ 20,881 was a somewhat more potent inhibitor than SQ 14,225, unlike rabbit lung enzyme. The Michaelis constant (Km) with hippuryl-l-histidyl-l-leucine was 1.6 mM. The molecular weight was estimated at 150,000 from sucrose density gradient centrifugation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a single polypeptide chain estimated at 130,000 daltons. Rabbit antibody to human lung enzyme was prepared by parenteral administration of pure angiotensin-converting enzyme in Freund's adjuvant. Rabbit antibody to human lung angiotensin-converting enzyme appeared to crossreact weakly with the rabbit enzyme and strongly inhibited the catalytic activity of the enzymes from human serum, lung, and lymph node. The specificity of the rabbit antibody and purity of the final human lung enzyme preparation was suggested by the single precipitin lines obtained by radial double immunodiffusion, and by the coincidence of enzyme catalytic activity and immunoreactivity on polyacrylamide gel electrophoresis, with both relatively pure and highly impure enzymes. Generally applicable sensitive analysis of acrylamide gels for immunoreactivity (and subsequently for any other activity) by use of intact gel slices in radial double immunodiffusion was devised. Human lung enzyme was very tightly bound to and catalytically active on anti-human enzyme antibody covalently bound to Sepharose 4B, and could not be readily dissociated without

  7. Predicting bulk damage in NIF triple harmonic generators

    SciTech Connect

    De Yoreo, J; Runkel, M; Williams, W

    1998-09-18

    Recently reported experiments have investigated the statistics of laser damage in KDP and KD*P. Automated damage tests have allowed cumulative failure and damage probability distributions to be constructed. Large area tests have investigated the feasibility of on-line laser conditioning and damage evolution for tripler harmonic generation (THG) crystals on the National Ignition Facility (NIF). These tests have shown that there is a nonzero probability of damage at NIF redline fluence (14.3 J/cm2, 351 nm, 3 ns) and that the damage pinpoint density evolves exponentially with fluence. In this paper, the results of these tests are used in conjunction with model spatial profiles of the NIP beam to predict the level of damage created in the THG crystal. A probabilistic calculation based on the overlap of the beam fluence and damage probabiity distribution shows that the overall damage probability is less than 3% for well-conditioned, high quality KDP/KD*P crystals of conventional or rapid growth. The number density of generated pinpoints has been calculated by mapping the damage evolution curves onto the NlF model profile. This shows that the number of damage pinpoints generated in high fluence portions of the NIF beam will be low for well-conditioned THG crystals. In contrast, unconditioned triplers of the same material will exhibit an increase in pinpoint density of greater than 20x. To test the validity of these calculations a 37 cm, conventionally grown KD*P tripler from the Beamlet laser was scatter mapped for bulk damage. The tripler had been exposed to NE-like fluences during its operational lifetime on Beamlet and exhibited very low levels of bulk pinpoint damage, essentially supporting the predictions based on tests and modeling.

  8. Modified Perfect Harmonics Cancellation Control of a Grid Interfaced SPV Power Generation

    NASA Astrophysics Data System (ADS)

    Singh, B.; Shahani, D. T.; Verma, A. K.

    2015-03-01

    This paper deals with a grid interfaced solar photo voltaic (SPV) power generating system with modified perfect harmonic cancellation (MPHC) control for power quality improvement in terms of mitigation of the current harmonics, power factor correction, control of point of common coupling (PCC) voltage with reactive power compensation and load balancing in a three phase distribution system. The proposed grid interfaced SPV system consists of a SPV array, a dc-dc boost converter and a voltage source converter (VSC) used for the compensation of other connected linear and nonlinear loads at PCC. The reference grid currents are estimated using MPHC method and control signals are derived by using pulse width modulation (PWM) current controller of VSC. The SPV power is fed to the common dc bus of VSC and dc-dc boost converter using maximum power point tracking (MPPT). The dc link voltage of VSC is regulated by using dc voltage proportional integral (PI) controller. The analysis of the proposed SPV power generating system is carried out under dc/ac short circuit and severe SPV-SX and SPV-TX intrusion.

  9. Phase noise mitigation of QPSK signal utilizing phase-locked multiplexing of signal harmonics and amplitude saturation.

    PubMed

    Mohajerin-Ariaei, Amirhossein; Ziyadi, Morteza; Chitgarha, Mohammad Reza; Almaiman, Ahmed; Cao, Yinwen; Shamee, Bishara; Yang, Jeng-Yuan; Akasaka, Youichi; Sekiya, Motoyoshi; Takasaka, Shigehiro; Sugizaki, Ryuichi; Touch, Joseph D; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Willner, Alan E

    2015-07-15

    We demonstrate an all-optical phase noise mitigation scheme based on the generation, delay, and coherent summation of higher order signal harmonics. The signal, its third-order harmonic, and their corresponding delayed variant conjugates create a staircase phase-transfer function that quantizes the phase of quadrature-phase-shift-keying (QPSK) signal to mitigate phase noise. The signal and the harmonics are automatically phase-locked multiplexed, avoiding the need for phase-based feedback loop and injection locking to maintain coherency. The residual phase noise converts to amplitude noise in the quantizer stage, which is suppressed by parametric amplification in the saturation regime. Phase noise reduction of ∼40% and OSNR-gain of ∼3  dB at BER 10(-3) are experimentally demonstrated for 20- and 30-Gbaud QPSK input signals.

  10. Crystal growth of organics for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Mazelsky, R.

    1993-01-01

    The crystal growth and characterization of organic and inorganic nonlinear optical materials were extensively studied. For example, inorganic crystals such as thallium arsenic selenide were studied in our laboratory for several years and crystals in sizes over 2.5 cm in diameter are available. Organic crystals are suitable for the ultraviolet and near infrared region, but are relatively less developed than their inorganic counterparts. Very high values of the second harmonic conversion efficiency and the electro-optic coefficient were reported for organic compounds. Single crystals of a binary organic alloy based on m.NA and CNA were grown and higher second harmonic conversion efficiency than the values reported for m.NA were observed.

  11. High-harmonic probing of electronic coherence in dynamically aligned molecules.

    PubMed

    Kraus, P M; Zhang, S B; Gijsbertsen, A; Lucchese, R R; Rohringer, N; Wörner, H J

    2013-12-13

    We introduce and demonstrate a new approach to measuring coherent electron wave packets using high-harmonic spectroscopy. By preparing a molecule in a coherent superposition of electronic states, we show that electronic coherence opens previously unobserved high-harmonic-generation channels that connect distinct but coherently related electronic states. Performing the measurements in dynamically aligned nitric oxide molecules we observe the complex temporal evolution of the electronic coherence under coupling to nuclear motion. Choosing a weakly allowed transition to prepare the wave packet, we demonstrate an unprecedented sensitivity that arises from optical interference between coherent and incoherent pathways. This mechanism converts a 0.1% excitation fraction into a ∼20% signal modulation.

  12. A closed-form solution to a viscoelastically supported Timoshenko beam under harmonic line load

    NASA Astrophysics Data System (ADS)

    Luo, W. L.; Xia, Y.; Zhou, X. Q.

    2016-05-01

    This study aims to formulate a closed-form solution to a viscoelastically supported Timoshenko beam under a harmonic line load. The differential governing equations of motion are converted into algebraic equations by assuming the deflection and rotation of the beam in harmonic forms with respect to time and space. The characteristic equation is biquadratic and thus contains 14 explicit roots. These roots are then substituted into Cauchy's residue theorem; consequently, five forms of the closed-form solution are generated. The present solution is consistent with that of an Euler-Bernoulli beam on a Winkler foundation, which is a special case of the present problem. The current solution is also verified through numerical examples.

  13. Comprehensive review of high power factor ac-dc boost converters for PFC applications

    NASA Astrophysics Data System (ADS)

    De Castro Pereira, Dênis; Da Silva, Márcio Renato; Mateus Silva, Elder; Lessa Tofoli, Fernando

    2015-08-01

    High power factor rectifiers have been consolidated as an effective solution to improve power quality indices in terms of input power factor correction, reduction in the total harmonic distortion of the input current and also regulated dc voltages. Within this context, this subject has motivated the introduction of numerous converter topologies based on classic dc-dc structures associated with novel control techniques, thus leading to the manufacturing of dedicated integrated circuits that allow high input power factor by adding a front-end stage to switch-mode converters. In particular, boost converters in continuous current mode (CCM) are widely employed since they allow obtaining minimised electromagnetic interference levels. This work is concerned with a literature review involving relevant ac-dc single-phase boost-based topologies with high input power factor. The evolution of aspects regarding the conventional boost converter is shown in terms of improved characteristics inherent to other ac-dc boost converters. Additionally, the work intends to be a fast and concise reference to single-phase ac-dc boost converters operating in CCM for engineers, researchers and experts in the field of power electronics by properly analysing and comparing the aforementioned rectifiers.

  14. Possible role of cochlear nonlinearity in the detection of mistuning of a harmonic component in a harmonic complex

    NASA Astrophysics Data System (ADS)

    Stoelinga, Christophe; Heo, Inseok; Long, Glenis; Lee, Jungmee; Lutfi, Robert; Chang, An-Chieh

    2015-12-01

    The human auditory system has a remarkable ability to "hear out" a wanted sound (target) in the background of unwanted sounds. One important property of sound which helps us hear-out the target is inharmonicity. When a single harmonic component of a harmonic complex is slightly mistuned, that component is heard to separate from the rest. At high harmonic numbers, where components are unresolved, the harmonic segregation effect is thought to result from detection of modulation of the time envelope (roughness cue) resulting from the mistuning. Neurophysiological research provides evidence that such envelope modulations are represented early in the auditory system, at the level of the auditory nerve. When the mistuned harmonic is a low harmonic, where components are resolved, the harmonic segregation is attributed to more centrally-located auditory processes, leading harmonic components to form a perceptual group heard separately from the mistuned component. Here we consider an alternative explanation that attributes the harmonic segregation to detection of modulation when both high and low harmonic numbers are mistuned. Specifically, we evaluate the possibility that distortion products in the cochlea generated by the mistuned component introduce detectable beating patterns for both high and low harmonic numbers. Distortion product otoacoustic emissions (DPOAEs) were measured using 3, 7, or 12-tone harmonic complexes with a fundamental frequency (F0) of 200 or 400 Hz. One of two harmonic components was mistuned at each F0: one when harmonics are expected to be resulted and the other from unresolved harmonics. Many non-harmonic DPOAEs are present whenever a harmonic component is mistuned. These non-harmonic DPOAEs are often separated by the amount of the mistuning (ΔF). This small frequency difference will generate a slow beating pattern at ΔF, because this beating is only present when a harmonic component is mistuned, it could provide a cue for behavioral detection

  15. Crystal Systems.

    ERIC Educational Resources Information Center

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  16. Virtual Crystallizer

    SciTech Connect

    Land, T A; Dylla-Spears, R; Thorsness, C B

    2006-08-29

    Large dihydrogen phosphate (KDP) crystals are grown in large crystallizers to provide raw material for the manufacture of optical components for large laser systems. It is a challenge to grow crystal with sufficient mass and geometric properties to allow large optical plates to be cut from them. In addition, KDP has long been the canonical solution crystal for study of growth processes. To assist in the production of the crystals and the understanding of crystal growth phenomena, analysis of growth habits of large KDP crystals has been studied, small scale kinetic experiments have been performed, mass transfer rates in model systems have been measured, and computational-fluid-mechanics tools have been used to develop an engineering model of the crystal growth process. The model has been tested by looking at its ability to simulate the growth of nine KDP boules that all weighed more than 200 kg.

  17. Large wind energy converter: Growian 3 MW

    NASA Technical Reports Server (NTRS)

    Koerber, F.; Thiele, H. A.

    1979-01-01

    The main features of the Growian wind energy converter are presented. Energy yield, environmental impact, and construction of the energy converter are discussed. Reliability of the windpowered system is assessed.

  18. High-harmonic spectroscopy of molecular isomers

    SciTech Connect

    Wong, M. C. H.; Brichta, J.-P.; Bhardwaj, V. R.; Spanner, M.; Patchkovskii, S.

    2011-11-15

    We demonstrate that high-order-harmonic generation (HHG) spectroscopy can be used to probe stereoisomers of randomly oriented 1,2-dichloroethylene (C{sub 2}H{sub 2}Cl{sub 2}) and 2-butene (C{sub 4}H{sub 8}). The high-harmonic spectra of these isomers are distinguishable over a range of laser intensities and wavelengths. Time-dependent numerical calculations of angle-dependent ionization yields for 1,2-dichloroethylene suggest that the harmonic spectra of molecular isomers reflect differences in their strong-field ionization. The subcycle ionization yields for the cis isomer are an order of magnitude higher than those for the trans isomer. The sensitivity in discrimination of the harmonic spectra of cis- and trans- isomers is greater than 8 and 5 for 1,2-dichloroethylene and 2-butene, respectively. We show that HHG spectroscopy cannot differentiate the harmonic spectra of the two enantiomers of the chiral molecule propylene oxide (C{sub 3}H{sub 6}O).

  19. Crystal growing

    NASA Technical Reports Server (NTRS)

    Neville, J. P.

    1990-01-01

    One objective is to demonstrate the way crystals grow and how they affect the behavior of material. Another objective is to compare the growth of crystals in metals and nonmetals. The procedures, which involve a supersaturated solution of a salt that will separate into crystals on cooling and the pouring off of an eutectic solution to expose the crystals formed by a solid solution when an alloy of two metals forms a solid and eutectic solution on cooling, are described.

  20. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z.

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  1. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  2. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  3. 12 CFR 1.6 - Convertible securities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Convertible securities. 1.6 Section 1.6 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY INVESTMENT SECURITIES § 1.6 Convertible securities. A national bank may not purchase securities convertible into stock at the option...

  4. GRACE Harmonic and Mascon Solutions at JPL

    NASA Astrophysics Data System (ADS)

    Watkins, M. M.; Yuan, D.; Kuang, D.; Bertiger, W.; Kim, M.; Kruizinga, G. L.

    2005-12-01

    Gravity field solutions at JPL over the past few years have explored use of range, range-rate, and range-acceleration K/Ka-band satellite-satellite data types (with and without GPS), and with both spherical harmonic and mascon-type local mass representations. Until recently, resource and computing limitations have limited the scope of our mascon and other local solutions to a few months and/or small spatial regions and the standard GRACE products have remained spherical harmonic fields. The use of a new very large (~500 node) beowulf machine at JPL is now enabling a wider range of solutions over longer time spans and deeper understanding of their characteristics. These include much higher spherical harmonic degrees, mascons, and hybrids of the two. We will present the current status for several solution types, strengths and weaknesses of each, and our assessments of limiting errors including data noise and aliasing sensitivity.

  5. The harmonic oscillator and nuclear physics

    NASA Technical Reports Server (NTRS)

    Rowe, D. J.

    1993-01-01

    The three-dimensional harmonic oscillator plays a central role in nuclear physics. It provides the underlying structure of the independent-particle shell model and gives rise to the dynamical group structures on which models of nuclear collective motion are based. It is shown that the three-dimensional harmonic oscillator features a rich variety of coherent states, including vibrations of the monopole, dipole, and quadrupole types, and rotations of the rigid flow, vortex flow, and irrotational flow types. Nuclear collective states exhibit all of these flows. It is also shown that the coherent state representations, which have their origins in applications to the dynamical groups of the simple harmonic oscillator, can be extended to vector coherent state representations with a much wider range of applicability. As a result, coherent state theory and vector coherent state theory become powerful tools in the application of algebraic methods in physics.

  6. Xe/+/ -induced ion-cyclotron harmonic waves

    NASA Astrophysics Data System (ADS)

    Jones, D.

    Xenon ion sources on an ejectable package separated from the main payload during the flights of Porcupine rockets F3 and F4 which were launched from Kiruna, Sweden on March 19 and 31, 1979, respectively. The effects of the xenon ion beam, detected by the LF (f less than 16 kHz) wideband electric field experiment and analyzed by using a sonograph, are discussed. Particular attention is given to the stimulation of the ion-cyclotron harmonic waves which are usually linked to the local proton gyro-frequency, but are sometimes related to half that frequency. It was found that in a plasma dominated by O(+) ions, a small amount (1-10%) of protons could cause an effect such that the O(+) cyclotron harmonic waves are set up by the hydrogen ions, the net result being the observation of harmonic emissions separated by the hydrogen ion gyro frequency.

  7. Second International Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo (Editor); Wolf, Kurt Bernardo (Editor)

    1995-01-01

    The Second International Workshop on Harmonic Oscillators was held at the Hotel Hacienda Cocoyoc from March 23 to 25, 1994. The Workshop gathered 67 participants; there were 10 invited lecturers, 30 plenary oral presentations, 15 posters, and plenty of discussion divided into the five sessions of this volume. The Organizing Committee was asked by the chairman of several Mexican funding agencies what exactly was meant by harmonic oscillators, and for what purpose the new research could be useful. Harmonic oscillators - as we explained - is a code name for a family of mathematical models based on the theory of Lie algebras and groups, with applications in a growing range of physical theories and technologies: molecular, atomic, nuclear and particle physics; quantum optics and communication theory.

  8. Degradation in finite-harmonic subcarrier demodulation

    NASA Technical Reports Server (NTRS)

    Feria, Y.; Townes, S.; Pham, T.

    1995-01-01

    Previous estimates on the degradations due to a subcarrier loop assume a square-wave subcarrier. This article provides a closed-form expression for the degradations due to the subcarrier loop when a finite number of harmonics are used to demodulate the subcarrier, as in the case of the buffered telemetry demodulator. We compared the degradations using a square wave and using finite harmonics in the subcarrier demodulation and found that, for a low loop signal-to-noise ratio, using finite harmonics leads to a lower degradation. The analysis is under the assumption that the phase noise in the subcarrier (SC) loop has a Tikhonov distribution. This assumption is valid for first-order loops.

  9. High harmonic phase in molecular nitrogen

    SciTech Connect

    McFarland, Brian K.

    2009-10-17

    Electronic structure in atoms and molecules modulates the amplitude and phase of high harmonic generation (HHG). We report measurements of the high harmonic spectral amplitude and phase in N{sub 2}. The phase is measured interferometrically by beating the N{sub 2} harmonics with those of an Ar reference oscillator in a gas mixture. A rapid phase shift of 0.2{pi} is observed in the vicinity of the HHG spectral minimum, where a shift of {pi} had been presumed [J. Itatani et al., Nature 432, 867 (2004)]. We compare the phase measurements to a simulation of the HHG recombination step in N{sub 2} that is based on a simple interference model. The results of the simulation suggest that modifications beyond the simple interference model are needed to explain HHG spectra in molecules.

  10. Microscopic optical buffering in a harmonic potential

    PubMed Central

    Sumetsky, M.

    2015-01-01

    In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices. PMID:26689546

  11. Extraordinary Second Harmonic Generation in Tungsten Disulfide Monolayers

    PubMed Central

    Janisch, Corey; Wang, Yuanxi; Ma, Ding; Mehta, Nikhil; Elías, Ana Laura; Perea-López, Néstor; Terrones, Mauricio; Crespi, Vincent; Liu, Zhiwen

    2014-01-01

    We investigate Second Harmonic Generation (SHG) in monolayer WS2 both deposited on a SiO2/Si substrate or suspended using transmission electron microscopy grids. We find unusually large second order nonlinear susceptibility, with an estimated value of deff ~ 4.5 nm/V nearly three orders of magnitude larger than other common nonlinear crystals. In order to quantitatively characterize the nonlinear susceptibility of two-dimensional (2D) materials, we have developed a formalism to model SHG based on the Green's function with a 2D nonlinear sheet source. In addition, polarized SHG is demonstrated as a useful method to probe the structural symmetry and crystal orientation of 2D materials. To understand the large second order nonlinear susceptibility of monolayer WS2, density functional theory based calculation is performed. Our analysis suggests the origin of the large nonlinear susceptibility in resonance enhancement and a large joint density of states, and yields an estimate of the nonlinear susceptibility value deff = 0.77 nm/V for monolayer WS2, which shows good order-of-magnitude agreement with the experimental result. PMID:24984953

  12. A dc to dc converter

    NASA Astrophysics Data System (ADS)

    Willis, A. E.; Gould, J. M.; Matheney, J. L.; Garrett, H.

    1984-01-01

    The object of the invention is to provide an improved converter for converting one direct current voltage to another. A plurality of phased square wave voltages are provided from a ring counter through amplifiers to a like plurality of output transformers. Each of these transformers has two windings, and S(1) winding and an S(2) winding. The S(1) windings are connected in series, then the S(2) windings are connected in series, and finally, the two sets of windings are connected in series. One of six SCRs is connected between each two series connected windings to a positive output terminal and one of diodes is connected between each set of two windings of a zero output terminal. By virtue of this configuration, a quite high average direct current voltage is obtained, which varies between full voltage and two-thirds full voltage rather than from full voltage to zero. Further, its variation, ripple frequency, is reduced to one-sixth of that present in a single phase system. Application to raising battery voltage for an ion propulsion system is mentioned.

  13. Broadband beam shaping with harmonic diffractive optics.

    PubMed

    Singh, Manisha; Tervo, Jani; Turunen, Jari

    2014-09-22

    We consider spatial shaping of broadband (either stationary or pulsed) spatially coherent light, comparing refractive, standard diffractive, and harmonic diffractive (modulo 2πM) elements. Considering frequency-integrated target profiles we show that, contrary to common belief, standard diffractive (M = 1) elements work reasonably well for, e.g., Gaussian femtosecond pulses and spatially coherent amplified-spontaneous-emission sources such as superluminescent diodes. It is also shown that harmonic elements with M ≥ 5 behave in essentially the same way as refractive elements and clearly outperform standard diffractive elements for highly broadband light.

  14. Nonlinear harmonic generation in distributed optical klystrons

    SciTech Connect

    H.P. Freund; George R. Neil

    2001-12-01

    A distributed optical klystron has the potential for dramatically shortening the total interaction length in high-gain free-electron lasers (INP 77-59, Novosibirsk, 1977; Nucl. Instr. and Meth A 304 (1991) 463) in comparison to a single-wiggler-segment configuration. This shortening can be even more dramatic if a nonlinear harmonic generation mechanism is used to reach the desired wavelength. An example operating at a 4.5{angstrom} fundamental and a 1.5{angstrom} harmonic is discussed.

  15. Harmonic demodulation of nonstationary shot noise.

    PubMed

    Gray, M B; Stevenson, A J; Bachor, H A; McClelland, D E

    1993-05-15

    We report on experimental demodulation of nonstationary shot noise, which is associated with strongly modulated light. For sinusoidal modulation and demodulation, measurements confirm theoretical predictions of 1.8-dB excess noise in the modulation quadrature and 3-dB noise reduction in the opposite quadrature, relative to the standard quantum limit. Demodulation with a third harmonic produces noise correlated with that which is due to the fundamental. Reducing excess noise by 0.8 dB in the modulation quadrature, by combining the fundamental and third harmonics in a 2:1 ratio, is shown to be feasible. PMID:19802263

  16. Spherical harmonic analysis of steady photospheric flows

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.

    1987-01-01

    A technique is presented in which full disk Doppler velocity measurements are analyzed using spherical harmonic functions to determine the characteristics of the spectrum of spherical harmonic modes and the nature of steady photospheric flows. Synthetic data are constructed in order to test the technique. In spite of the mode mixing due to the lack of information about the motions on the backside of the sun, solar rotation and differential rotation can be accurately measured and monitored for secular changes, and meridional circulations with small amplitudes can be measured. Furthermore, limb shift measurements can be accurately obtained, and supergranules can be fully resolved and separated from giant cells by their spatial characteristics.

  17. Quantum stochastic thermodynamic on harmonic networks

    NASA Astrophysics Data System (ADS)

    Deffner, Sebastian

    2016-01-01

    Fluctuation theorems are symmetry relations for the probability to observe an amount of entropy production in a finite-time process. In a recent paper Pigeon et al (2016 New. J. Phys. 18 013009) derived fluctuation theorems for harmonic networks by means of the large deviation theory. Their novel approach is illustrated with various examples of experimentally relevant systems. As a main result, however, Pigeon et al provide new insight how to consistently formulate quantum stochastic thermodynamics, and provide new and robust tools for the study of the thermodynamics of quantum harmonic networks.

  18. Damped harmonics and polynomial phase signals

    NASA Astrophysics Data System (ADS)

    Zhou, Guotong; Giannakis, Georgios B.

    1994-10-01

    The concern here is of retrieving damped harmonics and polynomial phase signals in the presence of additive noise. The damping function is not limited to the exponential model, and in certain cases, the additive noise does not have to be white. Three classes of algorithms are presented, namely DFT based, Kumaresan-Tufts type extensions, and subspace variants including the MUSIC algorithm. Preference should be based on the available data length and frequency separations. In addition, retrieval of self coupled damped harmonics, which may be present when nonlinearities exist in physical systems, is investigated. Simulation examples illustrate main points of the paper.

  19. The exact transformation from spherical harmonic to ellipsoidal harmonic coefficients for gravitational field modeling

    NASA Astrophysics Data System (ADS)

    Hu, Xuanyu

    2016-06-01

    The spherical and ellipsoidal harmonic series of the external gravitational potential for a given mass distribution are equivalent in their mutual region of uniform convergence. In an instructive case, the equality of the two series on the common coordinate surface of an infinitely large sphere reveals the exact correspondence between the spherical and ellipsoidal harmonic coefficients. The transformation between the two sets of coefficients can be accomplished via the numerical methods by Walter (Celest Mech 2:389-397, 1970) and Dechambre and Scheeres (Astron Astrophys 387:1114-1122, 2002), respectively. On the other hand, the harmonic coefficients are defined by the integrals of mass density moments in terms of the respective solid harmonics. This paper presents general algebraic formulas for expressing the solid ellipsoidal harmonics as a linear combination of the corresponding solid spherical harmonics. An exact transformation from spherical to ellipsoidal harmonic coefficients is found by incorporating these connecting expressions into the density integral. A computational procedure is proposed for the transformation. Numerical results based on the nearly ellipsoidal Martian moon, Phobos, are presented for validation of the method.

  20. Thermoelectric converters for alternating current standards

    NASA Astrophysics Data System (ADS)

    Anatychuk, L. I.; Taschuk, D. D.

    2012-06-01

    Thermoelectric converters of alternating current remain priority instruments when creating standard equipment. This work presents the results of design and manufacture of alternating current converter for a military standard of alternating current in Ukraine. Results of simulation of temperature distribution in converter elements, ways of optimization to improve the accuracy of alternating current signal reproduction are presented. Results of metrological trials are given. The quality of thermoelectric material specially created for alternating current metrology is verified. The converter was used in alternating current standard for the frequency range from 10 Hz to 30 MHz. The efficiency of using thermoelectric signal converters in measuring instruments is confirmed.

  1. Extraction of small boat harmonic signatures from passive sonar.

    PubMed

    Ogden, George L; Zurk, Lisa M; Jones, Mark E; Peterson, Mary E

    2011-06-01

    This paper investigates the extraction of acoustic signatures from small boats using a passive sonar system. Noise radiated from a small boats consists of broadband noise and harmonically related tones that correspond to engine and propeller specifications. A signal processing method to automatically extract the harmonic structure of noise radiated from small boats is developed. The Harmonic Extraction and Analysis Tool (HEAT) estimates the instantaneous fundamental frequency of the harmonic tones, refines the fundamental frequency estimate using a Kalman filter, and automatically extracts the amplitudes of the harmonic tonals to generate a harmonic signature for the boat. Results are presented that show the HEAT algorithms ability to extract these signatures.

  2. Resonant high-order harmonic generation from plasma ablation: Laser intensity dependence of the harmonic intensity and phase

    SciTech Connect

    Milosevic, D. B.

    2010-02-15

    Experimentally observed strong enhancement of a single high-order harmonic in harmonic generation from low-ionized laser plasma ablation is explained as resonant harmonic generation. The resonant harmonic intensity increases regularly with the increase of the laser intensity, while the phase of the resonant harmonic is almost independent of the laser intensity. This is in sharp contrast with the usual plateau and cutoff harmonics, the intensity of which exhibits wild oscillations while its phase changes rapidly with the laser intensity. The temporal profile of a group of harmonics, which includes the resonant harmonic, has the form of a broad peak in each laser-field half cycle. These characteristics of resonant harmonics can have an important application in attoscience. We illustrate our results using examples of Sn and Sb plasmas.

  3. Bandwidth enhancement of electro-optic field sensing using photonic down-mixing with harmonic sidebands.

    PubMed

    Lee, Dong-Joon; Whitaker, John F

    2008-09-15

    We demonstrate that harmonic sidebands of an electro-optic modulator's driving frequency can be used as the local oscillator in a photonic down-mixing process in order to significantly enhance the bandwidth of near-field, electro-optic, microwave measurements. The creation of second- and third-order-harmonic modulation sidebands on a laser-diode output are described, with heterodyne down-conversion of microwave signals taking place within an electro-optic sensor crystal. The measurement bandwidth of an electro-optic microwave probe can thus be enhanced by as much as a factor of three with respect to the use of conventional, fundamental-harmonic sidebands. Carrier-sideband analysis from the measured optical spectrum indicates that millimeter-wave-frequency local-oscillator sidebands can be created using a Ku-band electro-optic modulator and that the electro-optic-signal-modulation depth can be enhanced by suppressing the light-beam carrier component. Transverse near-field distributions from high frequency patch antennas are extracted using both second- and third-order-harmonic sidebands.

  4. Conduit Processes Driving Pre-explosive Harmonic Tremor in the 2009 Redoubt Volcano Eruption

    NASA Astrophysics Data System (ADS)

    Summers, P.; Dunham, E. M.

    2013-12-01

    During the 2009 eruption of Redoubt Volcano, Alaska, gliding harmonic tremor was observed before many vulcanian explosions. Though harmonic tremor is relatively common at volcanoes, the high fundamental frequency of these tremors (up to 30 Hz) is unique and of particular interest. Hotovec et al. (JVGR, 2013) linked this tremor to rapidly repeating magnitude ~1 earthquakes located a few kilometers beneath the vent. These events might be occurring as brittle failure of the magma or as slip along the margins of an obstruction within the conduit. Using a frictional faulting model, Dmitrieva et al. (Nature Geoscience, 2013) converted the seismicity and tremor signals into an estimate of the history of shear stresses acting on the fault surface and causing slip. Stressing rates increased, in a nonlinear manner, from less than 1 MPa/s to about 20 MPa/s over the final ten minutes before the explosions. Here we investigate what conduit processes could plausibly be responsible for such high stressing rates. One possibility is that a blockage develops in the conduit prior to each explosion, perhaps from a crystal-rich magma plug or collapse of the conduit walls. This obstacle temporarily prevents upward flow of magma, while deeper influx from below thus compresses and pressurizes magma in the conduit beneath the blockage. This compression largely occurs between the base of the obstruction and the H2O exsolution depth, which petrologic estimates of volatile content and standard solubility laws suggest is nominally located about a kilometer or two deeper than the blockage. We solve the unsteady conduit flow equations (mass and momentum balance for a compressible, viscous mixture of gas and liquid). Gas exsolution is treated with Henry's law, and in our present models exsolution begins abruptly below a critical pressure. No flow is permitted past the blockage and the system is driven by steady influx at depth. We find that as magma accumulates within the conduit beneath the

  5. Generation of green frequency comb from chirped χ{sup (2)} nonlinear photonic crystals

    SciTech Connect

    Lai, C.-M.; Chang, K.-H.; Yang, Z.-Y.; Fu, S.-H.; Tsai, S.-T.; Hsu, C.-W.; Peng, L.-H.; Yu, N. E.; Boudrioua, A.; Kung, A. H.

    2014-12-01

    Spectrally broad frequency comb generation over 510–555 nm range was reported on chirped quasi-phase-matching (QPM) χ{sup (2)} nonlinear photonic crystals of 12 mm length with periodicity stepwise increased from 5.9 μm to 7.1 μm. When pumped with nanosecond infrared (IR) frequency comb derived from a QPM optical parametric oscillator (OPO) and spanned over 1040 nm to 1090 nm wavelength range, the 520 nm to 545 nm up-converted green spectra were shown to consist of contributions from (a) second-harmonic generation among the signal or the idler modes, and (b) sum-frequency generation (SFG) from the neighboring pairs of the signal or the idler modes. These mechanisms led the up-converted green frequency comb to have the same mode spacing of 450 GHz as that in the IR-OPO pump comb. As the pump was further detuned from the aforementioned near-degeneracy point and moved toward the signal (1020–1040 nm) and the idler (1090–1110 nm) spectral range, the above QPM parametric processes were preserved in the chirped QPM devices to support up-converted green generation in the 510–520 nm and the 545–555 nm spectral regime. Additional 530–535 nm green spectral generation was also observed due to concurrence of multi-wavelength SFG processes between the (signal, idler) mode pairs. These mechanisms facilitate the chirped QPM device to support a single-pass up-conversion efficiency ∼10% when subject to an IR-OPO pump comb with 200 mW average power operated near- or off- the degeneracy point.

  6. Generation of green frequency comb from chirped χ(2) nonlinear photonic crystals

    NASA Astrophysics Data System (ADS)

    Lai, C.-M.; Chang, K.-H.; Yang, Z.-Y.; Fu, S.-H.; Tsai, S.-T.; Hsu, C.-W.; Yu, N. E.; Boudrioua, A.; Kung, A. H.; Peng, L.-H.

    2014-12-01

    Spectrally broad frequency comb generation over 510-555 nm range was reported on chirped quasi-phase-matching (QPM) χ(2) nonlinear photonic crystals of 12 mm length with periodicity stepwise increased from 5.9 μm to 7.1 μm. When pumped with nanosecond infrared (IR) frequency comb derived from a QPM optical parametric oscillator (OPO) and spanned over 1040 nm to 1090 nm wavelength range, the 520 nm to 545 nm up-converted green spectra were shown to consist of contributions from (a) second-harmonic generation among the signal or the idler modes, and (b) sum-frequency generation (SFG) from the neighboring pairs of the signal or the idler modes. These mechanisms led the up-converted green frequency comb to have the same mode spacing of 450 GHz as that in the IR-OPO pump comb. As the pump was further detuned from the aforementioned near-degeneracy point and moved toward the signal (1020-1040 nm) and the idler (1090-1110 nm) spectral range, the above QPM parametric processes were preserved in the chirped QPM devices to support up-converted green generation in the 510-520 nm and the 545-555 nm spectral regime. Additional 530-535 nm green spectral generation was also observed due to concurrence of multi-wavelength SFG processes between the (signal, idler) mode pairs. These mechanisms facilitate the chirped QPM device to support a single-pass up-conversion efficiency ˜10% when subject to an IR-OPO pump comb with 200 mW average power operated near- or off- the degeneracy point.

  7. Lysozyme Crystal

    NASA Technical Reports Server (NTRS)

    2004-01-01

    To the crystallographer, this may not be a diamond but it is just as priceless. A Lysozyme crystal grown in orbit looks great under a microscope, but the real test is X-ray crystallography. The colors are caused by polarizing filters. Proteins can form crystals generated by rows and columns of molecules that form up like soldiers on a parade ground. Shining X-rays through a crystal will produce a pattern of dots that can be decoded to reveal the arrangement of the atoms in the molecules making up the crystal. Like the troops in formation, uniformity and order are everything in X-ray crystallography. X-rays have much shorter wavelengths than visible light, so the best looking crystals under the microscope won't necessarily pass muster under the X-rays. In order to have crystals to use for X-ray diffraction studies, crystals need to be fairly large and well ordered. Scientists also need lots of crystals since exposure to air, the process of X-raying them, and other factors destroy them. Growing protein crystals in space has yielded striking results. Lysozyme's structure is well known and it has become a standard in many crystallization studies on Earth and in space.

  8. Microcomputer control of power converters

    SciTech Connect

    Alegria, C.M.; Freris, L.L.; Paiva, J.P.

    1984-08-01

    Thyristor power converters are charac terized by an inherent discrete control action and are, therefore, particularly well suited to on - line control by microcomputers. The paper presents a new design of digital controllers based upon powerful 16-bit or bit -slice microprocessors, which provide high firing time resolution and enough computing power to implement sophis ticated control strategies. Both hardware and software are discussed, with special emphasis on the firing con trol algorithms. The properties of Pulse Frequency Con trol (PFC) and Pulse Phase Control (PPC) are examined and small-signal discrete models are presented. These models are used in the analysis of constant current and constant extinction angle control through the z-transform method.

  9. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  10. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a thermionic converter to support an end an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housng, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  11. Wood stove having catalytic converter

    SciTech Connect

    Willson, A.C.

    1982-12-14

    A wood burning stove is formed with double front and rear side walls of heat conductive metal spaced apart by heat conductive spacer fins and providing air passageways by which room air is heated by conduction from the walls which are heated by the burning of wood deposited on a firebox floor supported in heat conducting relationship with the inner side walls. A catalytic converter is disposed over the fire area in the upper portion of the stove, and is arranged to receive preheated fresh secondary air which mixes with hot, incompletely combusted compounds from the fire and, in the presence of the catalyst, induces a secondary combustion of the substances. This mixture is channeled into a heat extraction chamber where the secondary combustion is completed and the resultant heat is transferred to the metal body of the stove. An exhaust passageway is provided for releasing the products of complete combustion into the atmosphere.

  12. Thermionic converter emitter support arrangement

    NASA Astrophysics Data System (ADS)

    Allen, Daniel T.

    1989-07-01

    A support is discussed which was provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs.

  13. Thermionic converter emitter support arrangement

    SciTech Connect

    Allen, D.T.

    1990-05-22

    This patent describes a support provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs.

  14. Thermionic converter emitter support arrangement

    SciTech Connect

    Allen, D.T.

    1989-07-06

    This document discusses a support provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs. 7 figs.

  15. Thermionic converter emitter support arrangement

    SciTech Connect

    Allen, D.T.

    1990-10-16

    A support is presented for use in a thermionic converted to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a large metal main support at the rear end that is attached to the housing, and metal main support. The spring structure can include a loose wafer captured between the Belleville springs.

  16. Sea water battery power converter

    NASA Astrophysics Data System (ADS)

    Hammond, Russell E.; Henry, John L.

    1991-04-01

    The invention converts the voltage output of a DC source to a higher voltage. A germanium transistor start-up circuit receives a DC supply voltage input and includes an astable multivibrator which produces a square wave voltage output that is transformed to a substantially DC steady-state voltage output by a transformer and a capacitor. This elevated voltage is provided to an oscillator circuit which provides two square wave outputs. Each output is provided to an array of invertors operably coupled to an array of field effect transistors. The transistors are operably coupled to a power transformer. The square wave outputs of the power transformer are full wave rectified to provide a DC output having a higher voltage than the system input voltage. The power transformer also provides another full wave rectified voltage which disables the start-up circuit to eliminate parasitic energy losses attributable to its continued oscillation.

  17. Harmonization of Clinical Laboratory Test Results.

    PubMed

    2016-02-01

    Clinical laboratory testing is now a global activity with laboratories no longer working in isolation but as regional and national networks, and often at international levels. We now have all of the electronic gadgetry via internet technology at our fingertips to rapidly and accurately measure and report on laboratory testing but are our test results harmonized? PMID:27683501

  18. Group Theory of Covariant Harmonic Oscillators

    ERIC Educational Resources Information Center

    Kim, Y. S.; Noz, Marilyn E.

    1978-01-01

    A simple and concrete example for illustrating the properties of noncompact groups is presented. The example is based on the covariant harmonic-oscillator formalism in which the relativistic wave functions carry a covariant-probability interpretation. This can be used in a group theory course for graduate students who have some background in…

  19. Harmonic Scalpel versus Monopolar Electrocauterization in Cholecystectomy

    PubMed Central

    Wen, Shunqian; Xie, Xueyi; Wu, Qing

    2016-01-01

    Background and Objectives: Laparoscopic cholecystectomy (LC) using surgical electrocautery is considered to be the gold standard procedure for the treatment of uncomplicated cholecystitis and cholelithiasis. The objective of the current study was to evaluate the effectiveness and safety of the Harmonic scalpel, an advanced laparoscopic technique associated with less thermal damage in LC, when compared to electrocautery. Methods: From October 2010 through June 2013, a total of 198 patients were randomly allocated to LC with a Harmonic scalpel (experimental group, 117 patients) or conventional monopolar electrocautery (control group, 81 patients). The main outcome measures were operative time, blood loss, conversion to laparotomy, postoperative hospital stay, post-LC pain, and cost effectiveness. Results: The 2 groups were comparable with respect to baseline patient characteristics. When compared to conventional monopolar electrocautery, there were no significant reductions in the operative time, bleeding, frequency of conversion to laparotomy, and duration of postoperative recovery with the Harmonic scalpel (P > .05 for all). Conclusions: Laparoscopic cholecystectomy using conventional monopolar electrocautery is as effective and safe as that with the Harmonic scalpel, for treating uncomplicated cholecystitis and cholelithiasis. PMID:27547026

  20. Harmonization of Clinical Laboratory Test Results

    PubMed Central

    2016-01-01

    EDITORIAL Clinical laboratory testing is now a global activity with laboratories no longer working in isolation but as regional and national networks, and often at international levels. We now have all of the electronic gadgetry via internet technology at our fingertips to rapidly and accurately measure and report on laboratory testing but are our test results harmonized? PMID:27683501

  1. On the simulation of harmonically related signals

    NASA Astrophysics Data System (ADS)

    Gerlach, Albert A.; Kunz, Edward L.; Anderson, Wendell L.; Flowers, Kenneth D.

    1988-06-01

    Narrowband harmonically related signals, embedded in broadband noise and other unrelated signals, occur in specific applications. To study these signals and to evaluate techniques for their discernment, it is convenient to model or simulate harmonically related signals in the laboratory. A means of accomplishing this task on a conventional digital computer is developed in discrete algorithm format. The resulting simulator uses parameters that allow one to select the mean frequency and harmonic ratio of the signals and to control both the extent and autocorrelation (or power spectral density) of the random signal-frequency fluctuations. Broadband noise and other nonharmonically related signals may also be accommodated in the simulator concept. Examples, using the algorithm, demonstrate its performance and its conformance with theoretical predictions. Conclusions: A relatively simple algorithm is formulated to simulate harmonically related narrowband signals with random frequency fluctuations in discrete format on a digital computer. Signal parameters are incorporated into the algorithm to select the signal mean frequencies and to control both the spectral bounds and the autocorrelation (or power spectral density) of the signal fluctuations. Examples, using the algorithm, demonstrate the performance of the signal simulator and its conformance with theoretical predictions.

  2. Light and harmonicity: the golden section

    NASA Astrophysics Data System (ADS)

    Raftopoulos, Dionysios G.

    2015-09-01

    Adhering to Werner Heisenberg's and to the school of Copenhagen's physical philosophy we introduce the localized observer as an absolutely necessary element of a consistent physical description of nature. Thus we have synthesized the theory of the harmonicity of the field of light, which attempts to present a new approach to the events in the human perceptible space. It is an axiomatic theory based on the selection of the projective space as the geometrical space of choice, while its first fundamental hypothesis is none other than special relativity theory's second hypothesis, properly modified. The result is that all our observations and measurements of physical entities always refer not to their present state but rather to a previous one, a conclusion evocative of the "shadows" paradigm in Plato's cave allegory. In the kinematics of a material point this previous state we call "conjugate position", which has been called the "retarded position" by Richard Feynman. We prove that the relation of the present position with its conjugate is ruled by a harmonic tetrad. Thus the relation of the elements of the geometrical (noetic) and the perceptible space is harmonic. In this work we show a consequence of this harmonic relation: the golden section.

  3. Harmonic generation with multiple wiggler schemes

    SciTech Connect

    Bonifacio, R.; De Salvo, L.; Pierini, P.

    1995-02-01

    In this paper the authors give a simple theoretical description of the basic physics of the single pass high gain free electron laser (FEL), describing in some detail the FEL bunching properties and the harmonic generation technique with a multiple-wiggler scheme or a high gain optical klystron configuration.

  4. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND...

  5. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND...

  6. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND...

  7. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND...

  8. Power Divider for Waveforms Rich in Harmonics

    NASA Technical Reports Server (NTRS)

    Sims, William Herbert, III

    2005-01-01

    A method for dividing the power of an electronic signal rich in harmonics involves the use of an improved divider topology. A divider designed with this topology could be used, for example, to propagate a square-wave signal in an amplifier designed with a push-pull configuration to enable the generation of more power than could be generated in another configuration.

  9. Harmonic cascade FEL designs for LUX

    SciTech Connect

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  10. Mapping from rectangular to harmonic representation

    SciTech Connect

    Schneider, W.; Bateman, G.

    1986-08-01

    An algorithm is developed to determine the Fourier harmonics representing the level contours of a scalar function given on a rectangular grid. This method is applied to the problem of computing the flux coordinates and flux surface average needed for 1-1/2-D transport codes and MHD stability codes from an equilibrium flux function given on a rectangular grid.

  11. Quantum harmonic oscillator in a thermal bath

    NASA Technical Reports Server (NTRS)

    Zhang, Yuhong

    1993-01-01

    The influence functional path-integral treatment of quantum Brownian motion is briefly reviewed. A newly derived exact master equation of a quantum harmonic oscillator coupled to a general environment at arbitrary temperature is discussed. It is applied to the problem of loss of quantum coherence.

  12. Quantum nondemolition measurements of harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.; Caves, C. M.; Zimmermann, M.; Sandberg, V. D.; Drever, R. W. P.

    1978-01-01

    Measuring systems to determine the real component of the complex amplitude of a harmonic oscillator are described. This amplitude is constant in the absence of driving forces, and the uncertainty principle accounts for the fact that only the real component can be measured precisely and continuously ('quantum nondemolition measurement'). Application of the measuring systems to the detection of gravitational waves is considered.

  13. Perfusion harmonic imaging of the human brain

    NASA Astrophysics Data System (ADS)

    Metzler, Volker H.; Seidel, Guenter; Wiesmann, Martin; Meyer, Karsten; Aach, Til

    2003-05-01

    The fast visualisation of cerebral microcirculation supports diagnosis of acute cerebrovascular diseases. However, the commonly used CT/MRI-based methods are time consuming and, moreover, costly. Therefore we propose an alternative approach to brain perfusion imaging by means of ultrasonography. In spite of the low signal/noise-ratio of transcranial ultrasound and the high impedance of the skull, flow images of cerebral blood flow can be derived by capturing the kinetics of appropriate contrast agents by harmonic ultrasound image sequences. In this paper we propose three different methods for human brain perfusion imaging, each of which yielding flow images indicating the status of the patient's cerebral microcirculation by visualising local flow parameters. Bolus harmonic imaging (BHI) displays the flow kinetics of bolus injections, while replenishment (RHI) and diminution harmonic imaging (DHI) compute flow characteristics from contrast agent continuous infusions. RHI measures the contrast agents kinetics in the influx phase and DHI displays the diminution kinetics of the contrast agent acquired from the decay phase. In clinical studies, BHI- and RHI-parameter images were found to represent comprehensive and reproducible distributions of physiological cerebral blood flow. For DHI it is shown, that bubble destruction and hence perfusion phenomena principally can be displayed. Generally, perfusion harmonic imaging enables reliable and fast bedside imaging of human brain perfusion. Due to its cost efficiency it complements cerebrovascular diagnostics by established CT/MRI-based methods.

  14. Conformation, orientation and interaction in molecular monolayers: A surface second harmonic and sum frequency generation study

    SciTech Connect

    Superfine, R.; Huang, J.Y.; Shen, Y.R.

    1988-12-01

    We have used sum frequency generation (SFG) to study the order in a silane monolayer before and after the deposition of a coadsorbed liquid crystal monolayer. We observe an increase in the order of the chain of the silane molecule induced by the interpenetration of the liquid crystal molecules. By using second harmonic generation (SHG) and SFG, we have studied the orientation and conformation of the liquid crystal molecule on clean and silane coated glass surfaces. On both surfaces, the biphenyl group is tilted by 70{degree} with the alkyl chain end pointing away from the surface. The shift in the C-H stretch frequencies in the coadsorbed system indicates a significant interaction between molecules. 9 refs., 3 figs.

  15. Harmonic phonon theory for calculating thermal conductivity spectrum from first-principles dispersion relations

    NASA Astrophysics Data System (ADS)

    Shiga, Takuma; Aketo, Daisuke; Feng, Lei; Shiomi, Junichiro

    2016-05-01

    In recent years, nanostructuring of dielectric and semiconducting crystals has enhanced controllability of their thermal conductivity. To carry out computational materials search for nanostructured materials with desirable thermal conductivity, a key property is the thermal conductivity spectrum of the original single crystal, which determines the appropriate length scale of nanostructures and mutual adaptability of different kinds of nanostructures. Although the first-principles phonon transport calculations have become accessible, the anharmonic lattice dynamics calculations are still expensive to scan many materials. To this end, we have developed an empirical model that describes the thermal conductivity spectrum in terms only of harmonic phonon properties and bulk thermal conductivity. The model was tested for several crystals with different structures and thermal conductivities, and was confirmed to reproduce the overall profiles of thermal conductivity spectra and their accumulation functions obtained by the first-principles anharmonic calculations.

  16. Structural and mechanical studies of cadmium manganese thiocyanate crystal

    NASA Astrophysics Data System (ADS)

    Manikandan, M. R.; Vijayaprasath, G.; babu, G. Anandha; Bhagavannarayan, G.; Vijayan, N.; Ravi, G.

    2012-06-01

    Single crystals of cadmium manganese thiocyanate (CMTC) have been synthesized successfully and grown by slow evaporation method. The structural perfection of the grown crystals has been analyzed by High resolution X-ray diffraction (HRXRD), which shows the crystalline perfection of the grown crystal is quite good. Optical behavior was assessed by UV-Vis analysis and found that no absorption in the UV visible region and it may be useful for second harmonic applications. The mechanical hardness of the grown crystals was studied and Vicker's microhardness, Stiffness constant was calculated.

  17. An efficient switch-mode power supply using an AC-DC interleaved boost converter and a DC-DC full-bridge topology

    NASA Astrophysics Data System (ADS)

    Lessa Tofoli, Fernando; Gallo, Carlos Alberto

    2011-04-01

    This work presents the conception and analysis of a switch-mode power supply with desirable characteristics of high power factor, low harmonic distortion, regulated output voltage, and high efficiency. An interleaved boost converter associated with a nondissipative snubber is used as a preregulator stage. Additionally, a soft switching full-bridge converter is chosen as DC-DC stage. The combination of both topologies results in the proposed switch-mode power supply. Theoretical background on each one of the converters is presented and analytical results are discussed in order to validate the proposal.

  18. Efficient broadband third harmonic frequency conversion via angular dispersion

    SciTech Connect

    Pennington, D.M.; Henesian, M.A.; Milam, D.; Eimerl, D.

    1995-07-18

    In this paper we present experimental measurements and theoretical modeling of third harmonic (3{omega}) conversion efficiency with optical bandwidth. Third harmonic conversion efficiency drops precipitously as the input bandwidth significantly exceeds the phase matching limitations of the conversion crystals. For Type I/Type II frequency tripling, conversion efficiency be-gins to decrease for bandwidths greater than {approximately}60 GHz. However, conversion efficiency corresponding to monochromatic phase-matched beams can be recovered provided that the instantaneous Propagation vectors are phase matched at all times. This is achieved by imposing angular spectral dispersion (ASD) on the input beam via a diffraction grating, with a dispersion such that the phase mismatch for each frequency is zero. Experiments were performed on the Optical Sciences Laser (OSL), a 1--100 J class laser at LLNL. These experiments used a 200 GHz bandwidth source produced by a multipassed electro-optic phase modulator. The spectrum produced was composed of discrete frequency components spaced at 3 GHz intervals. Angular dispersion was incorporated by the addition of a 1200 gr/mm diffraction grating oriented at the Littrow angle, and capable of rotation about the beam direction. Experiments were performed with a pulse length of 1-ns and a 1{omega} input intensity of {approximately} 4 GW/cm{sup 2} for near optimal dispersion for phase matching, 5.2 {mu}rad/GHz, with 0.1, 60, and 155 GHz bandwidth, as well as for partial dispersion compensation, 1.66 {mu}rad/GHz, with 155 GHz and 0.1 GHz bandwidth. The direction of dispersion was varied incrementally 360{degrees} about the beam diameter. The addition of the grating to the beamline reduced the narrowband conversion efficiency by approximately 10%.

  19. RNA Crystallization

    NASA Technical Reports Server (NTRS)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  20. Strongly Dispersive Transient Bragg Grating for High Harmonics

    SciTech Connect

    Farrell, J.; Spector, L.S.; Gaarde, M.B.; McFarland, B.K.; Bucksbaum, P.H.; Guhr, Markus; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.

    2010-06-04

    We create a transient Bragg grating in a high harmonic generation medium using two counterpropagating pulses. The Bragg grating disperses the harmonics in angle and can diffract a large bandwidth with temporal resolution limited only by the source size.

  1. Complete Vector Spherical Harmonic Expansion for Maxwell's Equations

    ERIC Educational Resources Information Center

    Lambert, R. H.

    1978-01-01

    Conventional expansions of solutions to Maxwell's equations in vector spherical harmonics apply only outside the sources. The complete solution, applying both inside and outside the sources, is given here. Harmonic time dependence is assumed. (Author/GA)

  2. Harmonic Current Suppression for PMSM by Repetitive Perfect Tracking Control

    NASA Astrophysics Data System (ADS)

    Nakai, Takahiro; Fujimoto, Hiroshi

    PM motor drives are widely used for high performance servo applications. However, PM motor has imperfect sinusoidal flux distribution which causes harmonic current. Dead time of inverter and current measurement error leads to harmonic current, too. The repetitive control method was applied to the harmonic current suppression. For the repetitive control which is based on the internal model principle, the characteristic of the harmonic suppression is excellent. However, it amplifies inter-harmonic components. The inter-harmonic components have frequencies with non-integral multiples of the fundamental frequency. Therefore, the feedforward compensation is applied for the harmonic current to improve a suppression characteristic. Authors proposed harmonic current suppression control of PM motor in αβ coordinate by using repetitive perfect tracking control with PWM-hold model. Finally, we show the advantages of proposed method by simulations and experiments.

  3. Recommended dietary allowances harmonization in Southeast Asia.

    PubMed

    Barba, Corazon Vc; Cabrera, Ma Isabel Z

    2008-01-01

    Issues and opportunities for RDA harmonization within the SEA region were first raised during the First Regional Forum and Workshop "RDAs: Scientific Basis and Future Directions", held in Singapore in March 1997. A regional review on RDAs in SEA showed general similarities for the different RDAs, although in some cases a country listed an exceptionally high or low RDA for a particular nutrient for a specific group. It also revealed differences in physiologic groupings and reference body weights, nutrients included and units of expression. Realizing these differences in RDA components between countries which makes technical composition different, a consensus on the need for regional collaboration and harmonization of RDAs was reached by participants from Indonesia, Malaysia, Philippines, Singapore, Thailand and Vietnam. A follow-up workshop was organized to work towards agreement throughout the region on common approaches, concepts and terminologies; application and uses, format and a research agenda. Round table discussions were held to arrive at specific recommendations for achieving harmonization. While divergence in opinions were expected, some clear-cut agreements were settled. Globalization envisions to achieve economic growth and development, with the effects expected to ripple through health, nutrition and welfare improvements. The harmonization of RDAs in SEA seeks to reach this vision by strengthening R and D capabilities (both logistic and manpower) within the region and within the countries in the region, as well as harmonizing the efforts of governments and industry within the region to reduce potential trade barriers such as those relating to food and nutrition quality assurance standards. PMID:18460439

  4. Protein Crystallization

    NASA Technical Reports Server (NTRS)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  5. Crystal growth and vibrational spectroscopic studies of the semiorganic non-linear optical crystal--bisthiourea magnesium sulphate.

    PubMed

    Krishnakumar, V; Ramachandraraja, C; Sundararajan, R S

    2007-09-01

    The semiorganic non-linear optical crystal bisthiourea magnesium sulphate (BTMS) was grown by slow evaporation technique using water as solvent. Vibrational spectra were recorded to determine the symmetries of molecular vibrations. The observed Raman and infrared bands were also assigned and discussed. The optical transmission spectral study was carried out to test the transmitting ability of the crystal in the visible range. The second harmonic generation test of BTMS revealed the non-linear nature of the crystal. The TGA/DTA curve was also recorded for the experimental crystal. PMID:17185029

  6. Method for Visualizing Switching Patterns for a Matrix Converter Using Instantaneous Space Vector Diagrams

    NASA Astrophysics Data System (ADS)

    Haruna, Junnosuke; Itoh, Jun-Ichi

    This paper discusses the characteristics of a matrix converter determined using instantaneous space vector diagrams. Since 27 switching patterns are available for the matrix converter, 27 types of output voltages and input currents can be obtained. The instantaneous output voltages and input currents are plotted on an instantaneous output voltage diagram and an input current diagram, respectively. Then, the switching patterns of the matrix converter are visualized. From the instantaneous space vector diagrams, the output voltage ripple and input current ripple can be determined on the basis of the vector selected from among 27 instantaneous output voltage/input current vectors. In addition, the instantaneous space vector diagrams can be used to analyze the switching times. In this study, six different of control methods for the matrix converter are evaluated by using instantaneous space vector diagrams and the total harmonic distortion of the output voltage and input current. The results lead to the conclusion that characteristics of the matrix converter can be effectively evaluated using the instantaneous space vector diagrams.

  7. Computational crystallization.

    PubMed

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed.

  8. The evolution of harmonic Indian musical drums: A mathematical perspective

    NASA Astrophysics Data System (ADS)

    Gaudet, Samuel; Gauthier, Claude; Léger, Sophie

    2006-03-01

    We explain using mathematics how harmonic musical drums were discovered by Indian artisans and musicians more than 2000 years ago. To this end, we introduce a harmonic error function which measures the quality of the harmonic relationship and degeneracy of the first modes of vibration of a centrally symmetric loaded membrane. We explain that although the tabla configuration found by the ancient Indians is the most natural one, other configurations exist and some are harmonically superior to the classical one.

  9. Efficient third harmonic generation of microjoule picosecond pulses at 355 nm in BiB3O6

    NASA Astrophysics Data System (ADS)

    Ghotbi, M.; Sun, Z.; Majchrowski, A.; Michalski, E.; Kityk, I. V.; Ebrahim-Zadeh, M.

    2006-10-01

    The authors report efficient third harmonic generation of microjoule picosecond pulses at 355nm in the nonlinear optical material BiB3O6. Using two crystals of BiB3O6 cut for type I (e +e→o) phase matching in optical yz plane for second and third harmonic generation and fundamental pulses from a mode-locked, amplified picosecond Nd:YAG laser at 1.064μm, they have achieved conversion efficiencies of as much as 50% at 355nm. Third harmonic pulse energies of up to 216μJ in 29ps pulses at 25Hz repetition rate have been obtained for 35ps fundamental pulses. They have also determined the magnitude of two-photon absorption coefficient in BiB3O6 at 355nm to be 0.71 and 1.37cm /GW for ordinary and extraordinary polarizations, respectively.

  10. Phase-matched second-harmonic generation in poled polymers by the use of birefringence

    NASA Astrophysics Data System (ADS)

    Tao, X. T.; Watanabe, T.; Zou, D. C.; Ukuda, H.; Miyata, S.

    1995-09-01

    Green light has been observed for the first time to the authors' knowledge by bulk phase-matched second-harmonic generation from a stretched main chain polyurea. The polyurea was synthesized from 4,4'-diphenylmethane diisocyanate and 4,4'-methylene bis(cyclohexylamine). The spin-coated film has an initial positive birefringence. Drawing further increased the birefringence, and the film can be used for phase matching just as in biaxial single crystals. The drawn and poled polymer films belong to the 2mm point group. Three independent nonlinear-optic coefficients were determined. The type I phase-matching characteristics were calculated and confirmed by experiments. We demonstrate that a highly effective second-harmonic-generation device with a long optical path length can be obtained by use of bulk phase-matchable poled polymer.

  11. Stokes vector based polarization resolved second harmonic microscopy of starch granules

    PubMed Central

    Mazumder, Nirmal; Qiu, Jianjun; Foreman, Matthew R.; Romero, Carlos Macías; Török, Peter; Kao, Fu-Jen

    2013-01-01

    We report on the measurement and analysis of the polarization state of second harmonic signals generated by starch granules, using a four-channel photon counting based Stokes-polarimeter. Various polarization parameters, such as the degree of polarization (DOP), the degree of linear polarization (DOLP), the degree of circular polarization (DOCP), and anisotropy are extracted from the 2D second harmonic Stokes images of starch granules. The concentric shell structure of a starch granule forms a natural photonic crystal structure. By integration over all the solid angle, it will allow very similar SHG quantum efficiency regardless of the angle or the states of incident polarization. Given type I phase matching and the concentric shell structure of a starch granule, one can easily infer the polarization states of the input beam from the resulting SH micrograph. PMID:23577289

  12. A Look at Damped Harmonic Oscillators through the Phase Plane

    ERIC Educational Resources Information Center

    Daneshbod, Yousef; Latulippe, Joe

    2011-01-01

    Damped harmonic oscillations appear naturally in many applications involving mechanical and electrical systems as well as in biological systems. Most students are introduced to harmonic motion in an elementary ordinary differential equation (ODE) course. Solutions to ODEs that describe simple harmonic motion are usually found by investigating the…

  13. Radiation-Tolerant DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Skutt, Glenn; Sable, Dan; Leslie, Leonard; Graham, Shawn

    2012-01-01

    A document discusses power converters suitable for space use that meet the DSCC MIL-PRF-38534 Appendix G radiation hardness level P classification. A method for qualifying commercially produced electronic parts for DC-DC converters per the Defense Supply Center Columbus (DSCC) radiation hardened assurance requirements was developed. Development and compliance testing of standard hybrid converters suitable for space use were completed for missions with total dose radiation requirements of up to 30 kRad. This innovation provides the same overall performance as standard hybrid converters, but includes assurance of radiation- tolerant design through components and design compliance testing. This availability of design-certified radiation-tolerant converters can significantly reduce total cost and delivery time for power converters for space applications that fit the appropriate DSCC classification (30 kRad).

  14. Performance of Power Converters at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Elbuluk, Malik E.; Gerber, Scott; Hammoud, Ahmad; Patterson, Richard L.

    2001-01-01

    Power converters capable of operation at cryogenic temperatures are anticipated to play an important role in the power system architecture of future NASA deep space missions. Design of such converters to survive cryogenic temperatures will improve the power system performance and reduce development and launch costs. Aerospace power systems are mainly a DC distribution network. Therefore, DC/DC and DC/AC converters provide the outputs needed to different loads at various power levels. Recently, research efforts have been performed at the NASA Glenn Research Center (GRC) to design and evaluate DC/DC converters that are capable of operating at cryogenic temperatures. This paper presents a summary of the research performed to evaluate the low temperature performance of five DC/DC converters. Various parameters were investigated as a function of temperature in the range of 20 to -196 C. Data pertaining to the output voltage regulation and efficiency of the converters is presented and discussed.

  15. Experimental verification of the mechanisms for nonlinear harmonic growth and suppression by harmonic injection in a traveling wave tube.

    PubMed

    Singh, A; Wöhlbier, J G; Booske, J H; Scharer, J E

    2004-05-21

    Understanding the generation and growth of nonlinear harmonic (and intermodulation) distortion in microwave amplifiers such as traveling wave tubes (TWTs), free electron lasers (FELs), and klystrons is of current research interest. Similar to FELs, the nonlinear harmonic growth rate scales with the harmonic number in TWTs. In klystrons, the wave number scaling applies to the nonlinear harmonic bunching and associated nonlinear space-charge waves. Using a custom-modified TWT that has sensors along the helix, we provide the first experimental confirmation of the scaling of nonlinear harmonic growth rate and wave number in TWTs. These scalings of a nonlinearly generated harmonic mode versus an injected linear harmonic mode imply that suppression by harmonic injection occurs at a single axial position that can be located as desired by changing the injected amplitude and phase.

  16. Experimental Verification of the Mechanisms for Nonlinear Harmonic Growth and Suppression by Harmonic Injection in a Traveling Wave Tube

    NASA Astrophysics Data System (ADS)

    Singh, A.; Wöhlbier, J. G.; Booske, J. H.; Scharer, J. E.

    2004-05-01

    Understanding the generation and growth of nonlinear harmonic (and intermodulation) distortion in microwave amplifiers such as traveling wave tubes (TWTs), free electron lasers (FELs), and klystrons is of current research interest. Similar to FELs, the nonlinear harmonic growth rate scales with the harmonic number in TWTs. In klystrons, the wave number scaling applies to the nonlinear harmonic bunching and associated nonlinear space-charge waves. Using a custom-modified TWT that has sensors along the helix, we provide the first experimental confirmation of the scaling of nonlinear harmonic growth rate and wave number in TWTs. These scalings of a nonlinearly generated harmonic mode versus an injected linear harmonic mode imply that suppression by harmonic injection occurs at a single axial position that can be located as desired by changing the injected amplitude and phase.

  17. Optical properties of Nd:YCOB crystal

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Zheng, Wei; Liu, Xinrong; Wang, Biao

    2001-10-01

    Ca4YO(BO3)3 crystal doped with Nd3+ has been grown by the Czochralski method under air atmosphere. The growth conditions were studied in the paper. X-ray powder diffractogram, the absorption spectra and infrared spectra have been measured. The effects of ions in the crystal on the absorption peak of OH- have been also discussed. The second harmonic generation (SHG) and self- frequency-doubling (SFD) experiments were carried out on the sample with the dimension of 4x4x8mm3.

  18. Gel growth of 2-amino-5-nitropyridinium dihydrogen phosphate organomineral crystals: X-ray and nonlinear optics characterization

    NASA Astrophysics Data System (ADS)

    Horiuchi, N.; Lefaucheux, F.; Robert, M. C.; Josse, D.; Khodja, S.; Zyss, J.

    1995-02-01

    2-Amino-5-nitropyridinium dihydrogen phosphate (2A5NPDP) is an organomineral material presenting interesting quadratic optical nonlinear properties, in particular towards second harmonic generation. Single crystals have been grown by spontaneous nucleation in tetramethoxysilane gel by slow cooling. X-ray characterization provides evidence of their good crystalline quality. Second harmonic generation experiments at 1.34 μm have confirmed the efficiency of these crystals and permitted inferring the d15 and d24 coefficients from the susceptibility tensor.

  19. Synthesis, crystal growth and physiochemical characterization of organic NLO crystal: L-ornithinium dipicrate (LODP)

    NASA Astrophysics Data System (ADS)

    Balaprabhakaran, S.; Chandrasekaran, J.; Babu, B.; Thirumurugan, R.; Anitha, K.

    2015-02-01

    L-ornithinium dipicrate (LODP) has been synthesized and good quality single crystals were grown by slow evaporation method at room temperature. Single crystal XRD confirms that the grown crystal belongs to the monoclinic system with the noncentrosymmetric space group P21. Powder X-ray diffraction study confirms the crystalline nature of the compound. FTIR spectral analysis confirms the functional group in the synthesized compound. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. The optical absorption spectrum shows the absence of absorption between 475 nm and 800 nm. The dielectric measurements were carried out to estimate the dielectric parameters of the grown crystal in the frequency range from 50 Hz to 5 MHz at various temperatures. The second harmonic property has been investigated by Kurtz-Perry powder technique. The relative SHG efficiency of LODP is found to be 14.57 times greater than that of the reference material KDP.

  20. Crystal growth and characterization of L-valine cadmium acetate a semiorganic NLO crystals

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, J.; Ilayabarathi, P.; Maadeswaran, P.

    2012-08-01

    A new semiorganic nonlinear optical material, L-valine cadmium acetate, was grown successfully from aqueous solution by slow evaporation method. The grown crystals characterized by using Powder X-ray diffraction analysis confirms the structure of the grown title compound. The functional groups have been identified using FTIR spectral data. Transmittance compound was analyzed by using UV-vis spectrum. The thermal behavior of the grown crystal was determined with the aid of thermogravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The dielectric constant was studied as a function of frequency for various temperatures. The grown crystal has positive photoconductivity nature. The fluorescence spectrum of the crystal was recorded and its optical band gap is about 3.4479 eV. Second order nonlinear optical property of the grown crystal has been confirmed by modified Kurtz-Perry powder second harmonic generation (SHG) test.

  1. Growth and characterization of nonlinear optical single crystal: Nicotinic L-tartaric

    NASA Astrophysics Data System (ADS)

    Sheelarani, V.; Shanthi, J.

    2015-06-01

    Nonlinear optical single crystals were grown from Nicotinic and L-Tartaric acid by slow evaporation technique at room temperature. Structure of the grown crystal was confirmed by single crystal X-ray diffraction studies, The crystallinity of the Nicotinic L-Tartaric (NLT) crystals was confirmed from the powder XRD pattern. The transparent range and cut off wavelength of the grown crystal was studied by the UV-Vis spectroscopic analysis.The thermal stability of the crystal was studied by TG-DTA. The second harmonic generation (SHG) efficiency of NLT was confirmed by Kurtz Perry technique.

  2. Growth and characterization of nonlinear optical single crystal: Nicotinic L-tartaric

    SciTech Connect

    Sheelarani, V.; Shanthi, J.

    2015-06-24

    Nonlinear optical single crystals were grown from Nicotinic and L-Tartaric acid by slow evaporation technique at room temperature. Structure of the grown crystal was confirmed by single crystal X-ray diffraction studies, The crystallinity of the Nicotinic L-Tartaric (NLT) crystals was confirmed from the powder XRD pattern. The transparent range and cut off wavelength of the grown crystal was studied by the UV–Vis spectroscopic analysis.The thermal stability of the crystal was studied by TG-DTA. The second harmonic generation (SHG) efficiency of NLT was confirmed by Kurtz Perry technique.

  3. Simplified Heat-Source/Thermionic Converter

    NASA Technical Reports Server (NTRS)

    Shimada, K.

    1983-01-01

    Radiation coupling of heat from heat-source cylinder to converter cylinder through vacuum gap eliminates need for high-temperature electrical insulators between reactor heat pipes and thermionic converters. In addition no radiatior heat pipe is necessary because collectors of thermionic converters from which excess heat must be removed radiate directly to space. New design concept is also applicable to terrestrial and non-nuclear thermionic power supplies.

  4. Ocean floor mounting of wave energy converters

    DOEpatents

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  5. Synthesis, crystal growth and characterization of nonlinear optical organic crystal: p-Toluidinium p-toluenesulphonate

    SciTech Connect

    Vijayakumar, P.; Anandha Babu, G.; Ramasamy, P.

    2012-04-15

    Graphical abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. p-TTS single crystal belongs to negative birefringence crystal. Second harmonic conversion efficiency of p-TTS has been found to be 1.3 times higher than that of KDP. Multiple shot surface laser damage threshold is determined to be 0.30 GW/cm{sup 2} at 1064 nm laser radiation. Highlights: Black-Right-Pointing-Pointer It deals with the synthesis, growth and characterization of p-TTS an organic NLO crystal. Black-Right-Pointing-Pointer Wide optical transparency window between 280 nm and 1100 nm. Black-Right-Pointing-Pointer Negative birefringence crystal and dispersion of birefringence is negligibly small. Black-Right-Pointing-Pointer Thermal study reveals that the grown crystal is stable up to 210 Degree-Sign C. Black-Right-Pointing-Pointer Multiple shot surface laser damage threshold is 0.30 GW/cm{sup 2} at 1064 nm laser radiation. -- Abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. The structural perfection of the grown p-TTS single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Fourier transform infrared spectral studies have been performed to identify the functional groups. The optical transmittance window and the lower cutoff wavelength of the grown crystals have been identified by UV-vis-IR studies. Birefringence of p-TTS crystal has been studied using channel spectrum measurement. The laser damage threshold value was measured using Nd:YAG laser. The second harmonic conversion efficiency of p-TTS has

  6. DC/DC Converter Stability Testing Study

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2008-01-01

    This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

  7. High voltage photovoltaic power converter

    DOEpatents

    Haigh, Ronald E.; Wojtczuk, Steve; Jacobson, Gerard F.; Hagans, Karla G.

    2001-01-01

    An array of independently connected photovoltaic cells on a semi-insulating substrate contains reflective coatings between the cells to enhance efficiency. A uniform, flat top laser beam profile is illuminated upon the array to produce electrical current having high voltage. An essentially wireless system includes a laser energy source being fed through optic fiber and cast upon the photovoltaic cell array to prevent stray electrical signals prior to use of the current from the array. Direct bandgap, single crystal semiconductor materials, such as GaAs, are commonly used in the array. Useful applications of the system include locations where high voltages are provided to confined spaces such as in explosive detonation, accelerators, photo cathodes and medical appliances.

  8. Bioimpedance Harmonic Analysis as a Diagnostic Tool to Assess Regional Circulation and Neural Activity

    NASA Astrophysics Data System (ADS)

    Mudraya, I. S.; Revenko, S. V.; Khodyreva, L. A.; Markosyan, T. G.; Dudareva, A. A.; Ibragimov, A. R.; Romich, V. V.; Kirpatovsky, V. I.

    2013-04-01

    The novel technique based on harmonic analysis of bioimpedance microvariations with original hard- and software complex incorporating a high-resolution impedance converter was used to assess the neural activity and circulation in human urinary bladder and penis in patients with pelvic pain, erectile dysfunction, and overactive bladder. The therapeutic effects of shock wave therapy and Botulinum toxin detrusor injections were evaluated quantitatively according to the spectral peaks at low 0.1 Hz frequency (M for Mayer wave), respiratory (R) and cardiac (C) rhythms with their harmonics. Enhanced baseline regional neural activity identified according to M and R peaks was found to be presumably sympathetic in pelvic pain patients, and parasympathetic - in patients with overactive bladder. Total pulsatile activity and pulsatile resonances found in the bladder as well as in the penile spectrum characterised regional circulation and vascular tone. The abnormal spectral parameters characteristic of the patients with genitourinary diseases shifted to the norm in the cases of efficient therapy. Bioimpedance harmonic analysis seems to be a potent tool to assess regional peculiarities of circulatory and autonomic nervous activity in the course of patient treatment.

  9. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K.

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  10. Crystal Data

    National Institute of Standards and Technology Data Gateway

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  11. The application of the symmetry properties of optical second harmonic generation to studies of interfaces and gases

    SciTech Connect

    Feller, M.B.

    1991-11-01

    Optical second harmonic generation has proven to be a powerful tool for studying interfaces. The symmetry properties of the process allow for surface sensitivity not available with other optical methods. In this thesis, we take advantage of these symmetry properties SHG to study a variety of interesting systems not previously studied with this technique. We show that optical second harmonic generation is an effective surface probe with a submonolayer sensitivity for media without inversion symmetry. We demonstrate the technique at a gallium arsenide surface, exploiting the different symmetry properties of the bulk and surface of the crystal to isolate the surface contribution. We also demonstrate that optical second harmonic generation can be used to determine the anisotropic orientational distribution of a surface monolayer of molecules. We apply the technique to study homogeneously aligned liquid crystal cells. To further explore the LC-polymer interface, we used SHG to study the surface memory effect. The surface memory effect is the rendering of an isotropic interface anisotropic by putting it in contact with an anisotropic bulk. Last, we describe some preliminary measurements of a time-resolved spectroscopic study of the phenomenon of second harmonic generation in a gas. The construction of a 500 microjoule pulsed, tunable laser source is described.

  12. Efficient 2(nd) and 4(th) harmonic generation of a single-frequency, continuous-wave fiber amplifier.

    PubMed

    Sudmeyer, Thomas; Imai, Yutaka; Masuda, Hisashi; Eguchi, Naoya; Saito, Masaki; Kubota, Shigeo

    2008-02-01

    We demonstrate efficient cavity-enhanced second and fourth harmonic generation of an air-cooled, continuous-wave (cw), single-frequency 1064 nm fiber-amplifier system. The second harmonic generator achieves up to 88% total external conversion efficiency, generating more than 20-W power at 532 nm wavelength in a diffraction-limited beam (M(2) < 1.05). The nonlinear medium is a critically phase-matched, 20-mm long, anti-reflection (AR) coated LBO crystal operated at 25 degrees C. The fourth harmonic generator is based on an AR-coated, Czochralski-grown beta-BaB(2)O(4) (BBO) crystal optimized for low loss and high damage threshold. Up to 12.2 W of 266-nm deep-UV (DUV) output is obtained using a 6-mm long critically phase-matched BBO operated at 40 degrees C. This power level is more than two times higher than previously reported for cw 266-nm generation. The total external conversion efficiency from the fundamental at 1064 nm to the fourth harmonic at 266 nm is >50%.

  13. 266  nm ultraviolet light generation in Ga-doped BaAlBO3F2 crystals.

    PubMed

    Yang, Lei; Yue, Yinchao; Yang, Feng; Hu, Zhanggui; Xu, Zuyan

    2016-04-01

    BaAlBO3F2 (BABF) crystals are a recently developed and promising nonlinear optical material, notably for the third harmonic generation of ultraviolet (UV) light at 355 nm. However, the fourth harmonic generation of UV light at 266 nm has never been obtained by using a BABF crystal due to its relatively small birefringence. We demonstrate that the birefringence of BABF can be effectively increased by doping it with Ga3+. The fourth harmonic generation of UV light at 266 nm was achieved for the first time in a Ga-doped BABF crystal. PMID:27192296

  14. Oriented single-crystal-to-single-crystal phase transition with dramatic changes in the dimensions of crystals.

    PubMed

    Liu, Guangfeng; Liu, Jie; Liu, Yang; Tao, Xutang

    2014-01-15

    We report here a new polymorph of cocrystal CuQ2-TCNQ that shows an oriented single-crystal-to-single-crystal phase transition along its a-axis at ambient conditions. Upon mechanical stimulation, it converts into another polymorph accompanied by almost doubling its length and halving its thickness. Our crystallographic studies indicate the dramatic changes in crystal dimensions resulted from the prominent changes of molecular stacking patterns. A reasonable mechanism for the phenomenon was proposed on the basis of the structural, microscopic, and thermal analysis.

  15. Harmonic generation by circularly polarized laser beams propagating in plasma

    SciTech Connect

    Agrawal, Ekta; Hemlata,; Jha, Pallavi

    2015-04-15

    An analytical theory is developed for studying the phenomenon of generation of harmonics by the propagation of an obliquely incident, circularly polarized laser beam in homogeneous, underdense plasma. The amplitudes of second and third harmonic radiation as well as detuning distance have been obtained and their variation with the angle of incidence is analyzed. The amplitude of harmonic radiation increases with the angle of incidence while the detuning distance decreases, for a given plasma electron density. It is observed that the generated second and third harmonic radiation is linearly and elliptically polarized, respectively. The harmonic radiation vanishes at normal incidence of the circularly polarized laser beam.

  16. Harmonized Medical Device Regulation: Need, Challenges, and Risks of not Harmonizing the Regulation in Asia

    PubMed Central

    Kaushik, A; Saini, KS; Anil, B; Rambabu, S

    2010-01-01

    Medical device sector is one of the most complex and challenging business segments of the healthcare industry with close collaboration between science and engineering. Despite the fact that Asia has 60% of the world population providing large market potential, Asian healthcare expenditure constitutes only 15% of the global healthcare expenditure. The accelerated ageing population and increasing prevalence of chronic disease are the key drivers that contribute toward the increase in the total healthcare expenditure on medical devices in the region. Several policies clearly showed the eagerness of the government to provide better healthcare infrastructure with better medical devices and facilities. The fundamental objective of the regulatory harmonization is to improve the efficiency of national economies and their ability to adopt to change and remain competitive. After the era of liberalization and globalization, the desires of developing economies is to ensure safety and performance of the product brought to their markets and for this harmonized regulation is an important tool for strengthening the same. If we talk about the industry need, then this approach will eliminate redundant requirements that do not contribute to safety and effectiveness. In addition, Asia is diverse in many respects and with it come the various challenges to harmonizing the regulation which includes diversity in culture, politics, economy, historical issues, etc. If, by any reason, the regulation of medical devices is not harmonized and consequently, the harmonized regulation is not adopted, then it leads to serious concerns like delayed or absent access to innovative technology, continued rise in the cost of medical therapies, etc. So this issue is written to attract all stakeholders to move toward the concept of harmonization, keeping in mind their need, challenges, and risks of not harmonizing the regulation as well. PMID:21331201

  17. Harmonized Medical Device Regulation: Need, Challenges, and Risks of not Harmonizing the Regulation in Asia.

    PubMed

    Kaushik, A; Saini, Ks; Anil, B; Rambabu, S

    2010-01-01

    Medical device sector is one of the most complex and challenging business segments of the healthcare industry with close collaboration between science and engineering. Despite the fact that Asia has 60% of the world population providing large market potential, Asian healthcare expenditure constitutes only 15% of the global healthcare expenditure. The accelerated ageing population and increasing prevalence of chronic disease are the key drivers that contribute toward the increase in the total healthcare expenditure on medical devices in the region. Several policies clearly showed the eagerness of the government to provide better healthcare infrastructure with better medical devices and facilities. The fundamental objective of the regulatory harmonization is to improve the efficiency of national economies and their ability to adopt to change and remain competitive. After the era of liberalization and globalization, the desires of developing economies is to ensure safety and performance of the product brought to their markets and for this harmonized regulation is an important tool for strengthening the same. If we talk about the industry need, then this approach will eliminate redundant requirements that do not contribute to safety and effectiveness. In addition, Asia is diverse in many respects and with it come the various challenges to harmonizing the regulation which includes diversity in culture, politics, economy, historical issues, etc. If, by any reason, the regulation of medical devices is not harmonized and consequently, the harmonized regulation is not adopted, then it leads to serious concerns like delayed or absent access to innovative technology, continued rise in the cost of medical therapies, etc. So this issue is written to attract all stakeholders to move toward the concept of harmonization, keeping in mind their need, challenges, and risks of not harmonizing the regulation as well.

  18. Harmonized Medical Device Regulation: Need, Challenges, and Risks of not Harmonizing the Regulation in Asia.

    PubMed

    Kaushik, A; Saini, Ks; Anil, B; Rambabu, S

    2010-01-01

    Medical device sector is one of the most complex and challenging business segments of the healthcare industry with close collaboration between science and engineering. Despite the fact that Asia has 60% of the world population providing large market potential, Asian healthcare expenditure constitutes only 15% of the global healthcare expenditure. The accelerated ageing population and increasing prevalence of chronic disease are the key drivers that contribute toward the increase in the total healthcare expenditure on medical devices in the region. Several policies clearly showed the eagerness of the government to provide better healthcare infrastructure with better medical devices and facilities. The fundamental objective of the regulatory harmonization is to improve the efficiency of national economies and their ability to adopt to change and remain competitive. After the era of liberalization and globalization, the desires of developing economies is to ensure safety and performance of the product brought to their markets and for this harmonized regulation is an important tool for strengthening the same. If we talk about the industry need, then this approach will eliminate redundant requirements that do not contribute to safety and effectiveness. In addition, Asia is diverse in many respects and with it come the various challenges to harmonizing the regulation which includes diversity in culture, politics, economy, historical issues, etc. If, by any reason, the regulation of medical devices is not harmonized and consequently, the harmonized regulation is not adopted, then it leads to serious concerns like delayed or absent access to innovative technology, continued rise in the cost of medical therapies, etc. So this issue is written to attract all stakeholders to move toward the concept of harmonization, keeping in mind their need, challenges, and risks of not harmonizing the regulation as well. PMID:21331201

  19. Investigation of Student Reasoning about Harmonic Motions

    NASA Astrophysics Data System (ADS)

    Tongnopparat, N.; Poonyawatpornkul, J.; Wattanakasiwich, P.

    This study aimed to investigate student reasoning about harmonic oscillations. We conducted a semi-structured interview based on three situations of harmonic motions—(1) a mass attaching to spring and horizontally oscillating without damping, (2) the same situation but vertically oscillating and (3) a mass attaching to spring and oscillating in viscous liquid. Forty-five second-year students taking a vibrations and wave course at Chiang Mai University, Thailand participated in a fifteen-minute interview, which was video-recorded. The videos were transcribed and analyzed by three physics instructors. As results, we found that most students had misconceptions about angular frequency and energy mostly in the second and third situations.

  20. Honeycomb optical lattices with harmonic confinement

    SciTech Connect

    Block, J. Kusk; Nygaard, N.

    2010-05-15

    We consider the fate of the Dirac points in the spectrum of a honeycomb optical lattice in the presence of a harmonic confining potential. By numerically solving the tight binding model, we calculate the density of states and find that the energy dependence can be understood from analytical arguments. In addition, we show that the density of states of the harmonically trapped lattice system can be understood by application of a local density approximation based on the density of states in the homogeneous lattice. The Dirac points are found to survive locally in the trap as evidenced by the local density of states. Furthermore, they give rise to a distinct spatial profile of a noninteracting Fermi gas.