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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. Harmonic analysis of a parallel-loaded resonant converter

    NASA Astrophysics Data System (ADS)

    Nelms, R. M.

    1991-07-01

    A method for calculating the harmonic components of the currents and voltages in a parallel-loaded resonant converter using frequency-domain techniques is presented. The converter is divided into an inverter section and a rectifier section. A harmonic model is developed for the resonant converter in which the rectifier section is treated as a voltage-dependent current sink. All voltages and currents in this model are represented by a Fourier series. The unknown coefficients in all Fourier series are calculated by using the harmonic model and Kirchhoff's laws. Because of the nonlinear nature of the rectifier section, an iterative technique must be utilized to find the unknown Fourier coefficients.

  3. Harmonic measurements from a group connected generator HVdc converter scheme

    SciTech Connect

    Macdonald, S.J.; Enright, W.; Arrillaga, J.; O`Brien, M.T.

    1995-10-01

    A recent CIGRE document published in ELECTRA has described the potential benefits of a direct connection of generators to HVdc converters. While many theoretical contributions have been made, no practical test data has become available so far. This paper reports on harmonic tests carried out at the Benmore end of the New Zealand HVdc link operating as a group connected scheme. It was found that the measured harmonic current levels were well below specified generator ratings. Dynamic simulation accurately predicted the harmonic currents whereas the results of a steady state formulation were less reliable.

  4. 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)

  5. 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. PMID:25995840

  6. 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

  7. A three-phase converter model for harmonic analysis of HVDC systems

    SciTech Connect

    Xu, W.; Drakos, J.E.; Mansour, Y.; Chang, A. )

    1994-07-01

    An equivalent circuit model is presented to model bridge converters for three-phase HVDC harmonic power flow analysis. The validity and accuracy of the model are verified by comparing simulation results against field test results. The model is interfaced with a multiphase harmonic load flow program to investigate the generation of non-characteristic harmonics from HVDC links and the flow of HVDC harmonics in a real system.

  8. Calculation of HVDC converter noncharacteristic harmonics using digital time-domain simulation method

    SciTech Connect

    Sarshar, A.; Iravani, M.R.; Li, J.

    1996-01-01

    In this paper, noncharacteristic harmonics of an HVdc converter station are calculated based on the use of digital time-domain simulation methods. An enhanced version of the Electromagnetic Transients Program (EMTP) is used for the studies. The noncharacteristic harmonics of interest are (1) the dc side triplen harmonics, and (2) the ac side second harmonic. Impacts of loading conditions, neutral filter, and converter firing angle on the dc side triplen harmonics are discussed. Effects of ac side network parameters, static VAR compensator (SVC), transformer half-cycle saturation, and Geomagnetically Induced Current (GIC) on the ac side second harmonic instability are also presented. This paper concludes that the digital time-domain simulation method provides significant flexibility for accurate prediction of (1) generation mechanism, and (2) adverse impacts of HVdc noncharacteristic harmonics.

  9. Converting Gravity-Bin Parameters To Spherical Harmonics

    NASA Technical Reports Server (NTRS)

    Wu, Jiun-Tsong; Bertiger, William I.; Wu, Sien-Chong

    1993-01-01

    New method of computation of gravitational field of Earth provides for conversion of gravity-bin parameters to coefficients of spherical harmonics. Traditional representation of gravitational field recovered by new method.

  10. A power converter as an active filter for the reduction of harmonic oscillations in supply network

    NASA Astrophysics Data System (ADS)

    Choe, Song-Yul

    1991-05-01

    An active filter is considered with regard to a harmonic oscillation compensation for a supply network. Self compensated converters with load independent current are used for the production of harmonic oscillations required for the compensation. Control design for single phase and three phase converters are presented. For single phase converters, the dynamics of flicker control are improved with an additional back coupling. A phased flicker control design is developed. A modulation process is implemented for the conversion of variance in pulse pattern. The control allows not only an increase of the bandwidth of the distance, but also a high reduction of the resonance step up.

  11. Novel calculation of HVDC converter harmonics by linearization in the time-domain

    SciTech Connect

    Perkins, B.K.; Iravani, M.R.

    1997-04-01

    There is an increasing interest in the steady-state analysis of high power converter circuits for the computation of both characteristic and uncharacteristic harmonics. Uncharacteristic harmonics arise due to asymmetries in excitation/operation and are of particular interest given their overall adverse effect on the power system. Frequency domain methods for harmonic analysis are efficient though not necessarily comprehensive; that is not all the necessary details of the system are simultaneously modeled. This paper presents a novel technique that is both efficient and comprehensive as the time domain nature of the differential/algebraic equations describing the converter operation is retained. Efficient convergence of the time domain boundary value problem is assured by an appropriate linearization. Subsequent Fourier analysis of the time domain solution yields the harmonic spectra. Comparison is made with time domain steady-state solutions obtained by brute-force computation.

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

    DOEpatents

    de Rooij, Michael Andrew (Clifton Park, NY); Steigerwald, Robert Louis (Burnt Hills, NY); Delgado, Eladio Clemente (Burnt Hills, NY)

    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.

  13. A gyroresonance harmonic converter to drive NCL, the next linear collider

    SciTech Connect

    Hirshfield, J.L. Physics Department, Yale University, Box 6666, New Haven, Connecticut 06511 ); Ganguly, A.K. )

    1992-07-01

    Current approaches are reviewed for developing an rf source for driving the Next Linear Collider (NLC) based on various gyroresonance interactions. An alternative mechanism is described, with the potential of converting 2.85 GHz power from a SLAC klystron to output at a harmonic ranging from 11.4 to 31.4 GHz. Preliminary calculations show that this new process can enjoy high conversion efficiency, strong resilience to axial momentum spread on the beam, and weak power flow into competing modes.

  14. Calculation of HVDC-converter harmonics in frequency domain with regard to asymmetries and comparison with time domain simulations

    SciTech Connect

    Rittiger, J.; Kulicke, B.

    1995-10-01

    In order to study the effects of large HVDC converters to the feeding ac networks, it is of importance to explain and to calculate harmonic phenomena which are a result of converter operation. During commissioning of real HVDC converters it could be seen, that harmonics resulting from unsymmetries in the system voltages or from unsymmetries in converter operation led to significant difficulties concerning the system design. For this reason, not only the effects of characteristic but also the effects of noncharacteristic converter harmonics must be taken into account. The aim is to describe the steady state harmonic behavior of the converter. The harmonic spectra are not determined by time domain analysis but instead the solution is found by frequency domain calculations. This can result in reduced calculation time in comparison to conventional fourier analysis of the time functions. The converter is interpreted as an amplitude modulator with voltage and current converter functions which describe the coupling of the dc circuit and the ac network through the converter. To verify the theory, comparison of frequency domain with time domain calculations were carried out.

  15. Design of a KA-Band Image Rejection Sub-Harmonic Down-Converter MMIC

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Yang, Tao; Yang, Ziqiang

    2010-12-01

    A Ka band image rejection sub-harmonic down-converter monolithic microwave integrated circuit (MMIC) is proposed. It contains a radio frequency (RF) amplifier, a broadband Lange coupler and two balanced mixers with two compact Marchand Baluns. The converter is fabricated by a commercial GaAs 0.2 ?m pseudomorphic high electron mobility transistor (pHEMT) process, the size of which is 1.5 mm 2 mm. Moreover, an improved nonlinear stability analysis method is presented in this paper. Based on the auxiliary generator (AG) technology, the method can analyze the nonlinear stability of circuits under the terminal impedance mismatched condition by setting the terminal load impedances as optimized variables. This method is applied to the sub-harmonic down-converter and is validated by the simulation and experiment. Experimental results show that from 30 GHz to 40 GHz, the conversion loss (CL) of the converter is less than 10 dB, and the image refection ratio (IMRR) is more than 15 dB.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    A photonic crystal (AB)2(DB)(AB)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.

  17. 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.

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

    PubMed

    Burda, Ioan; Tunyagi, Arthur

    2012-02-01

    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. PMID:22380125

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

    NASA Astrophysics Data System (ADS)

    Burda, Ioan; Tunyagi, Arthur

    2012-02-01

    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.

  20. 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 ?zxx (2 ), ?zyy (2 ) and the electric fields of the fundamental cavity mode.

  1. 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.

  2. Giant enhancement of second harmonic generation in one-dimensional defective nonlinear photonic crystals

    NASA Astrophysics Data System (ADS)

    Parvini, T. S.; Tehranchi, M. M.; Hamidi, S. M.

    2015-03-01

    In this paper, the second harmonic generations in finite size one-dimensional defective nonlinear photonic crystals have been investigated. To calculate the conversion efficiency, fundamental and second harmonic wave propagation among four proposed structures, we use the transfer matrix method. In the designed defective nonlinear photonic crystal structures, the linear and nonlinear optical parameters are both periodically modulated and thus the second harmonic generation efficiency can be several orders of magnitude larger than in a conventional quasi-phase-matched nonlinear structure with the same sample length.

  3. Enhancement of second harmonic generation in one-dimensional nonlinear photonic-crystal microcavities.

    PubMed

    Xia, Jinan

    2009-10-26

    A numerical iteration technique starting from the analytical solution of the fundamental wave and the second harmonic wave propagation equations in undepleted-pump approximation is presented for analysis of second harmonic generation in one-dimensional nonlinear photonic-crystal microcavities under pump light incidence at an arbitrary angle, accounting for pump depletion. Numerical results are in good agreement with experimental observation and theoretical predication by transfer matrix method. Analysis of the conversion efficiency of second harmonic generation in nonlinear photonic-crystal microcavities shows that dramatic enhancement of second harmonic generation occurs in the microcavities which have the optimal numbers of distributed Bragg reflector layers. The enhancement of nonlinear interactions is ascribed to mode resonance and localization of high intensity fundamental field, corresponding to the defect mode within the forbidden band of the photonic-crystal microcavities. PMID:19997231

  4. Phase-matched second-harmonic generation in slow-light photonic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Saravi, Sina; Diziain, Sverine; Zilk, Matthias; Setzpfandt, Frank; Pertsch, Thomas

    2015-12-01

    We present an analytical description of phase-matched second-harmonic generation in photonic crystal waveguides in the presence of loss. In particular, we investigate the case where the second-harmonic modes suffer from radiative losses. We use the adjoint field formalism to develop a coupled-mode theory that uses the quasinormal Bloch modes as the basis for modal expansion. To test our analytical description numerically, we propose a design in a lithium niobate photonic crystal slab waveguide, where a slow-light mode at the fundamental harmonic frequency is phase matched to a leaky mode at the second-harmonic frequency. The results of the numerical experiment agree with our analytical predictions.

  5. Quasi-phase-matched high harmonic generation in hollow core photonic crystal fibers.

    PubMed

    Ren, H; Nazarkin, A; Nold, J; Russell, P St J

    2008-10-13

    The potential of hollow core photonic crystal fiber as a nonlinear gas cell for efficient high harmonic generation is discussed. The feasibility of phase-matching this process by modulating the phase of ionization electrons using a counter-propagating laser field is shown. In this way, harmonics with energies of several hundreds of eV can be produced using fs-laser pump pulses of microJ energy. PMID:18852815

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

    PubMed

    Deyra, Loc; Martial, Igor; Didierjean, Julien; Balembois, Franois; Georges, Patrick

    2014-04-15

    We demonstrate a deep-UV laser at 236.5nm based on extracavity fourth-harmonic generation of a Q-switched Nd:YAG single-crystal fiber laser at 946nm. We first compare two nonlinear crystals available for second-harmonic generation: LBO and BiBO. The best results at 473nm are obtained with a BiBO crystal, with an average output power of 3.4W at 20kHz, corresponding to a second-harmonic generation efficiency of 38%. This blue laser is frequency-converted to 236.5nm in a BBO crystal with an overall fourth-harmonic generation yield of 6.5%, corresponding to an average output power of 600mW at 20kHz. This represents an order of magnitude increase in average power and energy compared to previously reported pulsed lasers at 236.5nm. This work opens the possibility of LIDAR detection of dangerous compounds for military or civilian applications. PMID:24978960

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

    DOEpatents

    Barker, Charles E. (Sunnyvale, CA); Eimerl, David (Livermore, CA); Velsko, Stephan P. (Livermore, CA); Roberts, David (Sagamore Hills, OH)

    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.

  8. 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.

  9. Nonlinear pulse compression in inhomogeneous photonic crystals upon backward second harmonic generation

    SciTech Connect

    Sapaev, U K; Kulagin, I A; Usmanov, T

    2009-04-30

    Frequency doubling of phase-modulated laser pulses, which is caused by a quasi-synchronous interaction of counterpropagating waves, is studied theoretically in crystals with an aperiodic domain structure. The simultaneous influence of the change in the domain period and the phase-modulation depth of fundamental radiation on the formation of a second-harmonic pulse is analysed in the nonstationary regime. It is shown that there exists an optimal relation between chirps in an aperiodic crystal and the phase modulation of fundamental radiation at which the maximum nonlinear compression of the second-harmonic pulse duration is possible. (nonlinear optical phenomena)

  10. 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.

  11. Cherenkov high-order harmonic generation by multistep cascading in {chi}{sup (2)} nonlinear photonic crystal

    SciTech Connect

    An Ning; Ren Huaijin; Zheng Yuanlin; Deng Xuewei; Chen Xianfeng

    2012-05-28

    We propose a scheme for efficient Cherenkov high-order harmonic generation. Second to fifth order harmonic wave are observed in a single periodically poled ferroelectric crystal in our experiment. The noncollinear high-order harmonic generation is produced via enhanced Cherenkov second harmonic cascaded with successive multistep sum-frequency generation with simultaneously longitudinal phase-matching. The emission angle and power dependencies are analyzed in detail experimentally, which coincide with theoretical predictions.

  12. 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.

  13. Nonequilibrium stationary state of a harmonic crystal with alternating masses

    NASA Astrophysics Data System (ADS)

    Kannan, Venkateshan; Dhar, Abhishek; Lebowitz, J. L.

    2012-04-01

    We analyze the nonequilibrium steady states (NESS) of a one-dimensional harmonic chain of N atoms with alternating masses connected to heat reservoirs at unequal temperatures. We find that the temperature profile defined through the local kinetic energy T(j)?/mj oscillates with period two in the bulk of the system. Depending on boundary conditions, either the heavier or the lighter particles in the bulk are hotter. We obtain explicit integral expressions for the bulk temperature profile and steady state current in the limit N??. These depend on whether N is odd or even. We also study similar temperature oscillations in the NESS of systems with noise in the dynamics. These die out as N??.

  14. Nonequilibrium stationary state of a harmonic crystal with alternating masses.

    PubMed

    Kannan, Venkateshan; Dhar, Abhishek; Lebowitz, J L

    2012-04-01

    We analyze the nonequilibrium steady states (NESS) of a one-dimensional harmonic chain of N atoms with alternating masses connected to heat reservoirs at unequal temperatures. We find that the temperature profile defined through the local kinetic energy T(j)?/mj oscillates with period two in the bulk of the system. Depending on boundary conditions, either the heavier or the lighter particles in the bulk are hotter. We obtain explicit integral expressions for the bulk temperature profile and steady state current in the limit N??. These depend on whether N is odd or even. We also study similar temperature oscillations in the NESS of systems with noise in the dynamics. These die out as N??. PMID:22680430

  15. Second optical harmonic near the surface of ferroelectric photonic crystals and photon traps

    NASA Astrophysics Data System (ADS)

    Voinov, Yu. P.; Gorelik, V. S.; Zaitsev, K. I.; Zlobina, L. I.; Sverbil', P. P.; Yurchenko, S. O.

    2015-03-01

    This paper reports on the results of experimental investigations of the generation of the second optical harmonic localized in a thin subsurface layer of ferroelectric photonic crystals and photon traps. To excite the second optical harmonic, a KGW: Yb solid-state pulsed-periodic laser generating the radiation with a wavelength of 1026 nm in a form of pulses 10-13 s long with a repetition frequency of 200 kHz at the average power of 0.1-3.5 W and power density of 109-1012 W/cm2 in a spot less than 100 ?m in diameter focused near the surface was used. Ferroelectrics, notably, barium titanate or sodium nitrite, were introduced into the pores between SiO2 nanoglobules. It is established that the maximal conversion efficiency of the exciting radiation into the second optical harmonic was several percents. The generation characteristics of the second optical harmonic near the surface of photonic crystals filled with ferroelectrics are compared with the generation of the second optical harmonic in ferroelectric photon traps of barium titanate ceramics and sodium nitrite microcrystals.

  16. Some Newly Developed Crystals for Measurement of Ultrafast Laser Pulses by Second Harmonic Generation

    NASA Astrophysics Data System (ADS)

    Kumbhakar, Pathik; Chatterjee, Sunanda; Kobayashi, Takayoshi

    Second harmonic generation in nonlinear optical crystal is a well-established technique for the characterization of ultrafast laser pulses. However, only selected nonlinear crystalline materials can be used due to their limitations in transparency cut-off and limited phase-matching range. It is observed that some newly discovered crystals, such as CLBO, KABO, LB4, and KBBF, have suitable characteristics for use in ultrafast nonlinear optical applications. We have calculated several linear and nonlinear optical parameters including phase-matching angle, angular and spectral acceptance bandwidths, walk-off angle, nonlinear coupling coefficient, and group-velocity mismatch for the generation of vacuum ultraviolet laser radiation in these crystals by type-I and type-II second harmonic generation techniques.

  17. 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.

  18. Parameters for efficient growth of second harmonic field in nonlinear photonic crystals

    NASA Astrophysics Data System (ADS)

    Joseph, Shereena; Khan, Mohd. Shahid; Hafiz, Aurangzeb Khurram

    2014-03-01

    The ultrashort pulse propagation and nonlinear second harmonic generation under the undepleted pump approximation in a quadratic nonlinear photonic crystal (NPC) structure is theoretically investigated and the optimized parameters for high second harmonic generation conversion efficiency are extracted. The transfer matrix method is used for the numerical formulation for oblique angle of incidence. A unique set of material combination GaInP/InAlP is selected as alternating nonlinear and linear layers. The NPC parameters like incident angle and layer thickness are manipulated to obtain the exact phase matching using double resonance condition for a fixed number of layers with known experimental material parameters.

  19. 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.

  20. CsLiB6O10 crystal: forth and fifth-harmonic generation in Nd:YAP laser

    NASA Astrophysics Data System (ADS)

    Kokh, Alexandr E.; Kononova, Nadegda G.; Lisova, Irina A.; Muraviov, Sergey V.

    2001-05-01

    An area of CsLiB6O10 (CLBO) phase equilibrium in the (Cs2O-Li2O) -- B2O3 -- MoO3 system was determined with spontaneous crystallization method. Crystals of 75 X 60 X 40 mm3 size have been growth in [100] direction with Kiropulos method. The forth-harmonic generation (270 nm) was achieved through the doubling of second-harmonic frequency in a multi-mode Nd:YAP laser in the type 1 collinear phase-matched geometry. The second-harmonic radiation in the technological laser of 3 mrad divergence was focused onto the input face of the crystal by a long-focus quartz lens. The input power density of the second harmonic was 300 MW/cm2. Using a 11.5 mm crystal, we showed that the highest efficiency of the forth-harmonic generation is 30%. The fifth harmonic (216 nm) in CLBO crystal was generated by composing the main laser beam and the forth-harmonic beam under the type 1 collinear phase-matching. Both beams were converged with dichroic and turning mirrors and then focused by a long-focus quartz lens. Our experiments showed that the fifth-harmonic generation in a multi-mode technological laser of 3 mrad divergence is possible in a 10 mm CLBO crystal of 23% optical conversion efficiency. The input power density of the forth harmonic was 100 MW/cm2. The use of longer CLBO crystal is less effective due to the nonlinear UV absorption and the walk off between the pump beam (1079 nm) and the harmonic beam.

  1. A positron source using an axially oriented crystal associated to a granular amorphous converter

    NASA Astrophysics Data System (ADS)

    Xu, Cheng-Hai; Robert, Chehab; Peter, Sievers; Xavier, Artru; Michel, Chevallier; Olivier, Dadoun; Pei, Guo-Xi; Vladimir, M. Strakhovenko; Alessandro, Variola

    2012-09-01

    A non-conventional positron source using the intense ? radiation from an axially oriented monocrystal which materializes into e+e- pairs in a granular amorphous converter is described. The enhancement of photon radiation by multi-GeV electrons crossing a tungsten crystal along its <111> axis is reported. The resulting enhancement of pair production in an amorphous converter placed 2 meters downstream, is also reported. Sweeping off the charged particles from the crystal by a bending magnet upstream of the converter allows a significant reduction of the deposited energy density. Substituting a granular target made of small spheres for the usual compact one, makes the energy dissipation easier. The deposited energy and corresponding heating are analyzed and solutions for cooling are proposed. The configurations studied here for this kind of positron source allow its consideration for unpolarized positrons for the ILC.

  2. Efficient second harmonic generation from large band gap II-VI semiconductor photonic crystal

    NASA Astrophysics Data System (ADS)

    Yang, H.; Xie, P.; Chan, S. K.; Zhang, Z. Q.; Sou, I. K.; Wong, G. K. L.; Wong, K. S.

    2005-09-01

    Dramatic enhancement of second harmonic generation (SHG) near the photonic band edge was observed in a one-dimensional ZnSe /ZnMgS semiconductor photonic crystal (PC) structure. Over two orders of magnitude increase in SHG intensity was observed at the photonic band edge at 1400nm compared to the nonphase matching region. The maximum SHG conversion efficiency of 0.8% is observed in only seven micrometers length of crystal. This enhancement came from a combination of large ZnSe second order susceptibility coefficient (?(2)), high density of optical modes and phase matching of the fundamental and second harmonic waves near the photonic band edge due to modification of the dispersion curve by the PC structure.

  3. 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 ?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?m 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

  4. Crystal lattice determination of ZnSe nanowires with polarization-dependent second harmonic generation microscopy

    NASA Astrophysics Data System (ADS)

    Cisek, Richard; Tokarz, Danielle; Hirmiz, Nehad; Saxena, Ankur; Shik, Alexander; Ruda, Harry E.; Barzda, Virginijus

    2014-12-01

    We demonstrate a noninvasive optical microscopy technique based on polarization-dependent second harmonic generation for determining the crystal lattice structure and microscopic heterogeneities within individual nanostructures. Differentiation between periodically twinned and wurtzite ZnSe nanowires (NWs) was demonstrated, and measurement of the cubic lattice rotation orientation around the NW axis was determined within 1 accuracy. Zinc blende NWs were differentiated from wurtzite. The technique can be used for quality inspection and optimization of growth conditions for nanostructures.

  5. Crystal lattice determination of ZnSe nanowires with polarization-dependent second harmonic generation microscopy.

    PubMed

    Cisek, Richard; Tokarz, Danielle; Hirmiz, Nehad; Saxena, Ankur; Shik, Alexander; Ruda, Harry E; Barzda, Virginijus

    2014-12-19

    We demonstrate a noninvasive optical microscopy technique based on polarization-dependent second harmonic generation for determining the crystal lattice structure and microscopic heterogeneities within individual nanostructures. Differentiation between periodically twinned and wurtzite ZnSe nanowires (NWs) was demonstrated, and measurement of the cubic lattice rotation orientation around the NW axis was determined within 1 accuracy. Zinc blende NWs were differentiated from wurtzite. The technique can be used for quality inspection and optimization of growth conditions for nanostructures. PMID:25431947

  6. Highly efficient nanojoule second harmonic generation of a femtosecond Cr:forsterite laser radiation in a lithium niobate crystal

    SciTech Connect

    Gordienko, Vyacheslav M; Dyakov, Vladimir A; Mikheev, Pavel M; Syrtsov, Vladimir S

    2006-11-30

    Highly efficient ({approx}70%) second harmonic generation of tightly focused femtosecond radiation from a Cr:forsterite laser is obtained in a LiNbO{sub 3} crystal. The pulse energy amounts to 10 nJ, the spatial and spectral quality of second harmonic radiation being preserved. (nonlinear optical phenomena)

  7. Conical second harmonic generation in KDP crystal assisted by optical elastic scattering.

    PubMed

    Li, Tianlun; Zhao, Xiaohui; Zheng, Yuanlin; Chen, Xianfeng

    2015-09-01

    We observed the generation of phase-matching conical second harmonic generation (SHG) inside KDP crystal under anomalous dispersion condition, which is attributed to complete phase-matching assisted by fundamental wave (FW) and scattering wave. The double-ring pattern of the conical SHG implies that elastic scattering can stimulate two different polarization states of scattering wave. Furthermore, SH ring of KDP displays inhomogeneous intensity around the ring, which has relevance to effective nonlinear coefficient, and it can be used to investigate crystal symmetry. PMID:26368476

  8. 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)

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    It is demonstrated that an L band metallic photonic crystal TEM-TE11 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 TE11 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.

  11. Thermal properties of molecular crystals through dispersion-corrected quasi-harmonic ab initio calculations: the case of urea.

    PubMed

    Erba, Alessandro; Maul, Jefferson; Civalleri, Bartolomeo

    2016-01-21

    An ab initio quantum-mechanical theoretical framework is presented to compute the thermal properties of molecular crystals. The present strategy combines dispersion-corrected density-functional-theory (DFT-D), harmonic phonon dispersion, quasi-harmonic approximation to the lattice dynamics for thermal expansion and thermodynamic functions, and quasi-static approximation for anisotropic thermo-elasticity. The proposed scheme is shown to reliably describe thermal properties of the urea molecular crystal by a thorough comparison with experimental data. PMID:26670006

  12. Lossless backward second-harmonic generation of extremely narrow subdiffractive beams in two-dimensional photonic crystals

    SciTech Connect

    Nistor, C.; Cojocaru, C.; Trull, J.; Karle, T. J.; Raj, R.; Raineri, F.; Staliunas, K.

    2010-09-15

    We report efficient second harmonic generation using extremely narrow beams (with diameter of the order of the wavelength) that propagate in the self-collimation (or nondiffractive) regime in a two-dimensional photonic crystal. We design and numerically test an AlGaAs photonic crystal membrane, where both fundamental and generated second harmonic beams propagate without diffraction and without out-of-plane losses. The characteristics of the generated second harmonic that is mainly propagating in the backward direction and the conversion efficiency of the proposed scheme are obtained by nonlinear finite-difference time-domain numerical simulations.

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  15. Feature extraction properties in optical wavelet transforms using liquid crystal polarization-converting devices

    NASA Astrophysics Data System (ADS)

    Honma, Michinori; Nose, Toshiaki; Sato, Susumu

    2001-05-01

    Liquid crystal (LC) molecular orientations and optical properties of LC polarization-converting devices are discussed. It is found that two stable LC molecular orientation states appear (we define them at the +/- 90 degree(s) and +/- 180 degree(s) twist modes), and the switching method between the two modes are discussed. Fourier transforms (FT) of the transmitted light of the LC polarization- converting device are performed by computer simulations. It is confirmed from the simulated FT results that both distribution profiles of the transmitted light beams in the +/- 90 degree(s) and +/- 280 degree(s) twist modes can be regarded as wavelets. Wavelet transforms using the LC polarization- converting device are simulated and feature extraction properties are discussed. It is found that the +/- 90 degree(s) and +/- 180 degree(s) twist modes can perform corner and edge extractions, respectively.

  16. Second harmonic generation in one-dimensional nonlinear photonic crystals solved by the transfer matrix method.

    PubMed

    Li, Jing-Juan; Li, Zhi-Yuan; Zhang, Dao-Zhong

    2007-05-01

    The transfer matrix method has been widely used to calculate the scattering of electromagnetic waves. In this paper, we develop the conventional transfer matrix method to analyze the problem of second harmonic generation in a one-dimensional multilayer nonlinear optical structure. In the designed nonlinear photonic crystal structure, the linear and nonlinear optical parameters are both periodically modulated. We have taken into account the multiple reflection and interference effects of both the linear and nonlinear optical waves during the construction of the transfer matrix for each composite layer. Application of this method to multilayer nonlinear photonic crystal structures with different refractive indices indicates that the proposed method is an exact approach and can simulate the generation of the second harmonic field precisely. In an optimum structure, the second harmonic generation efficiency can be several orders of magnitude larger than in a conventional quasi-phase-matched nonlinear structure with the same sample length. The reason is that, due to the presence of photonic band gap edges, the density of states of the electromagnetic fields is large, the group velocity is small, and the local field is enhanced. All three factors contribute to significant enhancement of the nonlinear optical interactions. PMID:17677185

  17. Noncollinear third-harmonic generation with large angular acceptance by noncritical phase matching in KDP crystal.

    PubMed

    Chen, Jing; Zheng, Yuanlin; An, Ning; Chen, Xianfeng

    2015-10-01

    The scheme of prefocusing to focus sum frequency generation (SFG) without a lens is proposed and experimentally verified in this study. Noncollinear type-I noncritical phase-matching SFG to generate a third-harmonic wave with large angular acceptance is presented. The principle of broad angular acceptance and the advantages of this PM configuration are also described in detail. External angular bandwidth of 7.33° for noncollinear SFG was measured in a 2 mm long KH2PO4 (KDP) crystal, which is in reasonably good agreement with the theoretical calculation. The mechanism of broadband SFG and the prefocusing scheme make it possible for the realization of convergent third-harmonic generation without involving a lens, which provides a promising way to avoid damage to optical components during the focusing of high-energy UV light in high-power laser facilities. PMID:26421562

  18. Second Harmonic Light Scattering Study of a Twist-Bend Nematic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Pardaev, Shokir; Gleeson, James; Jakli, Antal; Sprunt, Samuel

    2015-03-01

    The twist-bend nematic phase exhibited by certain liquid crystalline dimers has been the subject of intensive recent investigation. In this report we present the results of angle-resolved second harmonic (SH) light scattering measurements from a twist-bend (TB) nematic liquid crystal for various combinations of the fundamental and second harmonic polarizations. These measurements reveal a polarization-dependent pretransitional temperature dependence of the SH signal, as well as an evolution of the SH scattering pattern below the transition (in the TB phase). We will discuss our results in terms of other recent experiments, as well as the current theoretical understanding of the nematic to TB transition and the nature of the TB phase. We thank O. Parri at Merck Chemicals Ltd., Southampton, UK for providing the studied material for us. Acknowledgement: NSF DMR-0964765 and DMR-1307674.

  19. Third harmonic frequency generation by type-I critically phase-matched LiB3O5 crystal by means of optically active quartz crystal.

    PubMed

    Gapontsev, Valentin P; Tyrtyshnyy, Valentin A; Vershinin, Oleg I; Davydov, Boris L; Oulianov, Dmitri A

    2013-02-11

    We present a method of third harmonic generation at 355 nm by frequency mixing of fundamental and second harmonic radiation of an ytterbium nanosecond pulsed all-fiber laser in a type-I phase-matched LiB(3)O(5) (LBO) crystal where originally orthogonal polarization planes of the fundamental and second harmonic beams are aligned by an optically active quartz crystal. 8 W of ultraviolet light at 355 nm were achieved with 40% conversion efficiency from 1064 nm radiation. The conversion efficiency obtained in a type-I phase-matched LBO THG crystal was 1.6 times higher than the one achieved in a type-II LBO crystal at similar experimental conditions. In comparison to half-wave plates traditionally used for polarization alignment the optically active quartz crystal has much lower temperature dependence and requires simpler optical alignment. PMID:23481827

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    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.

  1. Multiple copies of orbital angular momentum states through second-harmonic generation in a two-dimensional periodically poled LiTaO3 crystal

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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 LiTaO3 (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 l2 are simultaneously generated by the input fundamental beam with an OAM of l1. The OAM conservation law (i.e., l2 = 2l1) 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.

  2. Evaluation of crystal structure in TlInS2 by optical second- harmonic generation

    NASA Astrophysics Data System (ADS)

    Wakita, K.; Hagiwara, M.; Paucar, R.; Shim, Y.; Mimura, K.; Mamedov, N.

    2015-06-01

    Second-harmonic generation (SHG) in layered TlInS2 crystals was studied over the temperature range of 77-300 K using a confocal laser microscope system. As expected, the SHG signal was observed in the low temperature ferroelectric phase of the layered compound. In addition, the polarization properties of the SHG signals of TlInS2 were investigated in the 80-180 K range. The results are in good agreement with those of the symmetric space group C32 in the ferroelectric phase.

  3. Blue light second harmonic generation in the organic crystal ortho-Dicyanovinyl-anisole

    SciTech Connect

    Grossman, C.H.; Schulhofer-Wohl, S.; Thoen, E.R.

    1997-01-01

    Type I phase matched second harmonic generation (SHG) in the organic crystal ortho-Dicyanovinyl-anisole (DIVA) has been measured for a range of near infrared fundamental wavelengths (855{endash}960 nm). Turning curves for type I phase matched SHG were derived from measured refractive index values and show noncritical phase matching at 860. Measured type I phase matched SHG is in close agreement with the calculated results and gives effective SHG coefficients ranging from 1.9 to 5.9 times as large as d{sub 32} of potassium niobate. {copyright} {ital 1997 American Institute of Physics.}

  4. 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.

  5. Period-doubling bifurcation in two-stage power factor correction converters using the method of incremental harmonic balance and Floquet theory

    NASA Astrophysics Data System (ADS)

    Wang, Fa-Qiang; Zhang, Hao; Ma, Xi-Kui

    2012-02-01

    In this paper, period-doubling bifurcation in a two-stage power factor correction converter is analyzed by using the method of incremental harmonic balance (IHB) and Floquet theory. A two-stage power factor correction converter typically employs a cascade configuration of a pre-regulator boost power factor correction converter with average current mode control to achieve a near unity power factor and a tightly regulated post-regulator DCDC Buck converter with voltage feedback control to regulate the output voltage. Based on the assumption that the tightly regulated post-regulator DCDC Buck converter is represented as a constant power sink and some other assumptions, the simplified model of the two-stage power factor correction converter is derived and its approximate periodic solution is calculated by the method of IHB. And then, the stability of the system is investigated by using Floquet theory and the stable boundaries are presented on the selected parameter spaces. Finally, some experimental results are given to confirm the effectiveness of the theoretical analysis.

  6. Analysis of Second Harmonic Generation of a KDP crystal based on multi-scale topography simulation

    NASA Astrophysics Data System (ADS)

    Liu, Hai Tao; Su, Rui Feng; Sun, Ya Zhou; Wang, He Ran

    2015-04-01

    The surface topography of the supporting frame of a KDP crystal is studied, as well as its influence on the deformation and stress of the KDP crystal, together with the Second Harmonic Generation (SHG). A comprehensive model incorporating principles of multi-scale surface analysis, mechanics, and optics is proposed, and it is applied to investigate the surface topography of the supporting frame, the deformation and stress of the KDP crystal, as well as the SHG efficiency. The surface topography is analyzed using fractural theory, and then classified according to its multi-scale specifics. Based on the surface analysis results, the mounting configuration of the KDP crystal is modeled and analyzed in global and local modes, respectively, using the Finite Element Method (FEM). Moreover, deformation and stress of the KDP crystal that is induced by the mechanical mounting is studied using the FEM, together with the effects of the surface topography on them. Furthermore, the change of the refractive index that induced by the deformation and stress are calculated, respectively, the results of which is applied to studied the phase mismatch, and the SHG efficiency considering the phase mismatch is eventually obtained. The numerical results demonstrate that the frame surface with multi-scale dimensions has diverse influences on the distortion and stress, as well as the SHG efficiency.

  7. Crystallization and second harmonic generation in thermally poled niobium borophosphate glasses

    NASA Astrophysics Data System (ADS)

    Malakho, Artem; Dussauze, Marc; Fargin, Evelyne; Lazoryak, Bogdan; Rodriguez, Vincent; Adamietz, Frederic

    2005-06-01

    Crystallization of glasses with compositions (1- x)(0.95 NaPO 3+0.05 Na 2B 4O 7)+ xNb 2O 5, x=0.4, 0.43, 0.45, 0.48 was investigated by differential scanning calorimetry and X-ray powder diffraction. Crystallization of two phases was observed in the glasses with x=0.43-0.48. First phase is a sodium niobate with the structure of tetragonal tungsten bronze ( T720-760 C) and second phase is Na 4Nb 8P 4O 32 ( T830-850 C). The crystallization of sodium niobate is correlated with increasing of nonlinear optical efficiency reported for thermally poled glasses with x>0.4. The results of Raman spectroscopy show the formation of three-dimensional (3D) niobium oxide framework in the glasses with increase of niobium concentration. This framework is supposed to have tetragonal tungsten bronze structure and to be responsible for nonlinear optical properties of the glass. Second harmonic generation signals of as prepared and crystallized glass after thermal poling are compared. The nucleation and crystallization do not improve the NLO properties of the glasses under study.

  8. Characterization of salt interferences in second-harmonic generation detection of protein crystals.

    PubMed

    Closser, R G; Gualtieri, E J; Newman, J A; Simpson, G J

    2013-12-01

    Studies were undertaken to assess the merits and limitations of second-harmonic generation (SHG) for the selective detection of protein and polypeptide crystal formation, focusing on the potential for false positives from SHG-active salts present in crystallization media. The SHG activities of salts commonly used in protein crystallization were measured and quantitatively compared with reference samples. Out of 19 salts investigated, six produced significant background SHG and 15 of the 96 wells of a sparse-matrix screen produced SHG upon solvent evaporation. SHG-active salts include phosphates, hydrated sulfates, formates and tartrates, while chlorides, acetates and anhydrous sulfates resulted in no detectable SHG activity. The identified SHG-active salts produced a range of signal intensities spanning nearly three orders of magnitude. However, even the weakest SHG-active salt produced signals that were several orders of magnitude greater than those produced by typical protein crystals. In general, SHG-active salts were identifiable through characteristically strong SHG and negligible two-photon-excited ultraviolet fluorescence (TPE-UVF). Exceptions included trials containing either potassium dihydrogen phosphate or ammonium formate, which produced particularly strong SHG, but with residual weak TPE-UVF signals that could potentially complicate discrimination in crystallization experiments using these precipitants. PMID:24282335

  9. Second-harmonic generation in an atomic phase-matched nonlinear 2D crystal (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Zhao, Mervin; Ye, Ziliang; Ye, Yu; Zhu, Hanyu; Wang, Yuan; Iwasa, Yoshihiro; Zhang, Xiang

    2015-09-01

    The second harmonic generation (SHG) produced from two-dimensional atomic crystals have been utilized recently in studying the grain boundaries and electronic structure of such ultra-thin materials. However, the SHG in many of these crystals, such as transition metal dichalcogenides (TMDCs), only occur in odd numbered layers with limited intensity due to their noncentrosymmetric nature. Here, we probe the SHG from the bulk noncentrosymmetric molybdenum disulfide (MoS2). Whereas the commonly studied 2H crystal phase's anti-parallel nonlinear dipoles in adjacent layers give an oscillatory SH response, the parallel nonlinear dipoles of each atomic layer in the 3R phase constructively interfere to amplify the nonlinear light. Due to this interference, we observed the atomically phase-matched condition yielding a quadratic dependence between the intensity and layer number. Additionally, we probed the layer evolution of the A and B excitonic transitions in 3R-MoS2 using SHG spectroscopy and found distinct electronic structure differences arising from the crystal geometry. These findings demonstrate the dramatic effect of the symmetry and layer stacking of these atomic crystals.

  10. Efficient second-harmonic generation of a broadband radiation by control of the temperature distribution along a nonlinear crystal.

    PubMed

    Regelskis, K; eludevi?ius, J; Gavrilin, N; Ra?iukaitis, G

    2012-12-17

    We demonstrate an efficient technique for the second harmonic generation (SHG) of the broadband radiation based on the temperature gradient along a nonlinear crystal. The characteristics of Type I non-critical phase-matched SHG of broadband radiation in the LiB(3)O(5) (LBO) crystal with the temperature gradient imposed along the crystal were investigated both numerically and experimentally. The frequency doubling efficiency of the broadband pulsed fiber laser radiation as high as 68% has been demonstrated. PMID:23263092

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  13. 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.

  14. Laser-Induced Damage in DKDP Crystals under Simultaneous Exposure to Laser Harmonics

    SciTech Connect

    Negres, R A; DeMange, P; Radousky, H B; Demos, S G

    2005-10-28

    While KDP and DKDP crystals remain the only viable solution for frequency conversion in large aperture laser systems in the foreseeable future, our understanding of damage behavior in the presence of multiple colors is very limited. Such conditions exist during normal operation where, for third harmonic generation, 1{omega}, 2{omega} and 3{omega} components are present with different energy ratios as they propagate inside the crystal. The objective of this work is to shed light into the damage behavior of frequency conversion crystals during operational conditions as well as probe the fundamental mechanisms of damage initiation. We have performed a series of experiments to quantify the damage performance of pristine (unconditioned) DKDP material under simultaneous exposure to 2{omega} and 3{omega} laser pulses from a 3-ns Nd:YAG laser system as a function of the laser influences at each frequency. Results show that simultaneous dual wavelength exposure leads to a much larger damage density as compared to the total damage resulting from separate exposure at each wavelength. Furthermore, under such excitation conditions, the damage performance is directly related to and can be predicted from the damage behavior of the crystal at each wavelength separately while the mechanism and type of defects responsible for damage initiation are shown to be the same at both 2{omega} and 3{omega} excitation.

  15. Simulation of thermo-optic coupling in the thermally anisotropic gallium selenide crystal for second harmonic generation

    NASA Astrophysics Data System (ADS)

    Chao, Zhang Wen; An, Ye Hong; Andreev, Yu M.; Grechin, S. G.; Lanskii, G. V.

    2014-07-01

    A second harmonic generation model of space-time thermo-optic coupling was proposed in thermal anisotropic nonlinear crystals, where an iterative approach was used to approximate the temperature anisotropy. The coupling process was simulated with the aid of derived analytical formulas in a gallium selenide crystal, pumped by a pulsed carbon dioxide laser. The intensities of the fundamental and harmonic beams, conversion efficiencies and temperature distributions were demonstrated during the evolution processes. The results showed that a compensation for the phase mismatch induced by the thermal effect can mitigate the reduction of conversion efficiency better than temperature control.

  16. High efficiency 12.5 J second-harmonic generation from CsLiB6O10 nonlinear crystal by diode-pumped Nd:glass laser.

    PubMed

    Sekine, Takashi; Sakai, Hiroshi; Takeuchi, Yasuki; Hatano, Yuma; Kawashima, Toshiyuki; Kan, Hirofumi; Kawanaka, Junji; Miyanaga, Noriaki; Norimatsu, Takayoshi

    2013-04-01

    A 12.5 J second-harmonic generation with 71.5% conversion efficiency at 0.6 Hz repetition rate from a diode-pumped Nd:glass laser system has been demonstrated by using a CsLiB(6)O(10) (CLBO) nonlinear optical crystal as a frequency doubler. The CLBO has aperture of 40 mm x 40 mm and thickness of 14 mm with Type-II phase matching. The CLBO is mounted into a housing which flows dry nitrogen gas on the CLBO's face. There is no significant reduction of conversion efficiency by exposing of over 600,000 shots for intermissive experiment during 3 years. In our knowledge, these experimental results of output energy and conversion efficiency are highest performance as second-harmonic generation of a diode-pumped solid state laser by using one CLBO nonlinear crystal. In this paper, potential of the CLBO as a frequency converter for repetitive kJ class laser is discussed. PMID:23571928

  17. Equations for second-harmonic generation under quasi-phase-matched interaction conditions in nonlinear crystals with a regular domain structure

    SciTech Connect

    Dmitriev, Valentin G; Yur'ev, Yu V

    1998-11-30

    Equations describing second-harmonic generation under quasi-phase-matched interaction conditions in crystals with a regular domain structure are derived. It is shown that appropriate substitution of variables makes these equations exactly identical with those describing second-harmonic generation in the usual homogeneous crystals. This analogy is used to obtained an expression for the second-harmonic amplitude in the case of inexact quasi-phase-matched interaction. (nonlinear optical phenomena and devices)

  18. Photonic band structure in one-dimensional nonlinear crystal: Analysis of harmonic stability

    NASA Astrophysics Data System (ADS)

    Avendao, Carlos G.; Reyes, J. Adrin

    2015-01-01

    We consider a one-dimensional nonlinear photonic crystal consisting of an infinite set of concentrated equidistant scatterers inserted in a linear dielectric medium. Each of the scatterers is made by a very thin layer of a nonlinear medium with high refractive index that we model by a delta function. We show that the nonlinear optical exact solutions of this system form an intensity dependent band structure. To analyze the stability of these solutions we consider a modulation harmonic perturbation of these solutions whose amplitudes are slightly above the instability threshold. We demonstrate that the nonlinearity gives rise to an oscillatory instability of the solutions, which is a localized version of the well-known modulational instability of the nonlinear Schrodinger equation. We show that the linear harmonic perturbation forms as well a band structure whose allowed bands coincide for some intervals with those of the nonlinear band structure of the solutions for which case the structures are unstable whereas in the region where both the linear and nonlinear bands do not coincide, the nonlinear waves are indeed stable so that they conform spatial solitons.

  19. Time-Resolved Third Order Harmonic Generation on Shocked Silicon Crystals

    NASA Astrophysics Data System (ADS)

    Dalton, D. A.; Grigsby, W.; Quevedo, H.; Bernstein, A. C.; Ditmire, T.

    2008-04-01

    We are using nonlinear optical diagnostics to probe the shock-induced melt transition in silicon. Pump-probe shock experiments on [100] Si crystals were carried out using the Ti:Sapphire THOR laser (800 nm, 1 J, 600 ps-chirped, 40 fs-compressed). Two dimensional interferometry was used to map rear surface displacement at discrete times to infer a peak shock pressure. Third order harmonic generation (THG) is used to probe the bulk material's long range order, while a reflectivity diagnostic is used in conjuction with the THG diagnostic to determine it's validity. Preliminary evidence shows the anomalous response that at shock pressures <100 kbar (˜elastic limit) the THG signal does not decrease; however, at higher pressures of ˜300-400 kbar the THG signal falls dramatically indicating fast crystalline disordering.

  20. Optical harmonic generation in hollow-core photonic-crystal fibres: analysis of optical losses and phase-matching conditions

    SciTech Connect

    Naumov, A N; Zheltikov, Aleksei M

    2002-02-28

    We consider hollow-core fibres with a microstructure photonic-crystal cladding, which open a unique opportunity of implementing nonlinear-optical interactions of waveguide modes with transverse sizes on the order of several microns in the gas phase. Phase-matching conditions for optical harmonic generation can be improved in higher waveguide modes of hollow-core photonic-crystal fibres by optimising parameters of the gas medium filling the fibre and characteristics of the fibre. (optical fibres)

  1. The origin of inhibition of high power second harmonic generation in periodically poled lithium niobate crystal

    NASA Astrophysics Data System (ADS)

    Li, Guohui; Wang, Jing; Cui, Yanxia

    2015-10-01

    This paper investigates the origin of the inhibition of the second harmonic generation (SHG) in a periodically poled lithium niobate (PPLN) crystal by using coupled-mode equations in which both absorption and photorefractive properties of the crystal were taken into account. SHG, using fundamental laser beams with radii of 150, 33, and 25 ?m, respectively, were calculated. The calculated results showed that the changes of refractive index difference resulting from the photorefractive effect were ?300 times smaller than that from absorption-induced heating in SHG using a fundamental laser beam with a radius of 150 ?m. However, in SHG using a fundamental laser beam with a radius smaller than 33 ?m, the changes of refractive index difference resulting from the photorefractive effect were comparable to those resulting from absorption-induced heating. It revealed that the photorefractive effect is one of the main factors that inhibits the SHG using a fundamental laser beam with a radius smaller than 33 ?m at high pump powers.

  2. Neutron transfer kernels in the resonance domain in the harmonic crystal model.

    SciTech Connect

    Naberejnev, D. G.

    1999-12-21

    To describe neutron scattering the resonance domain of the nuclear fuel isotopes, the static model is widely in use in nuclear data processing codes. With this model the influence of chemical binding on the transfer cross section is not taken into account since the nucleus is considered to be in rest and isolated in the laboratory system. Further, the application of the free gas model to the resonant scattering of neutrons shows that the up-scattering probability is strongly dependent on the incident neutron energy. If the latter is smaller than the resonance energy then the free gas model predicts an enormous chance for the neutron to gain energy after collision. Neither the static nor free gas model is adequate to describe the resonant scattering of neutrons in a crystal. This fact can induce non-negligible errors in reactor calculations and, in particular, in the estimation of the Doppler coefficient. In the present paper the author proposes the theoretical study of the possibility to estimate the neutron transfer cross sections in the harmonic crystal approximation.

  3. High luminous flux from single crystal phosphor-converted laser-based white lighting system.

    PubMed

    Cantore, Michael; Pfaff, Nathan; Farrell, Robert M; Speck, James S; Nakamura, Shuji; DenBaars, Steven P

    2016-01-25

    The efficiency droop of light emitting diodes (LEDs) with increasing current density limits the amount of light emitted per wafer area. Since low current densities are required for high efficiency operation, many LED die are needed for high power white light illumination systems. In contrast, the carrier density of laser diodes (LDs) clamps at threshold, so the efficiency of LDs does not droop above threshold and high efficiencies can be achieved at very high current densities. The use of a high power blue GaN-based LD coupled with a single crystal Ce-doped yttrium aluminum garnet (YAG:Ce) sample was investigated for white light illumination applications. Under CW operation, a single phosphor-converted LD (pc-LD) die produced a peak luminous efficacy of 86.7 lm/W at 1.4 A and 4.24 V and a peak luminous flux of 1100 lm at 3.0 A and 4.85 V with a luminous efficacy of 75.6 lm/W. Simulations of a pc-LD confirm that the single crystal YAG:Ce sample did not experience thermal quenching at peak LD operating efficiency. These results show that a single pc-LD die is capable of emitting enough luminous flux for use in a high power white light illumination system. PMID:26832576

  4. Efficient collinear fourth-harmonic generation by two-channel multistep cascading in a single two-dimensional nonlinear photonic crystal.

    PubMed

    de Sterke, M; Saltiel, S M; Kivshar, Y S

    2001-04-15

    We investigate efficient fourth-harmonic generation in a single two-dimensional (2D) quadratically nonlinear photonic crystal. We propose a novel parametric process that starts with phase-matched generation of a pair of symmetric second-harmonic waves, which then interact to produce a fourth-harmonic wave that is collinear to the fundamental. We show that this process is more efficient than conventional fourth-harmonic-generation schemes by a factor that reaches 4 at low intensities and discuss how to design and optimize the nonlinear 2D photonic crystals that are implemented in LiNbO(3) and LiTaO(3) . PMID:18040378

  5. Backward emission angle of microscopic second-harmonic generation from crystallized type I collagen fiber

    NASA Astrophysics Data System (ADS)

    Tian, Long; Wei, Huajiang; Jin, Ying; Liu, Hanping; Guo, Zhouyi; Deng, Xiaoyuan

    2011-07-01

    A theoretical model that deals with SHG from crystallized type I collagen fiber formed by a bundle of fibrils is established. By introducing a density distribution function of dipoles within fibrils assembly into the dipole theory and combining with structural order (m,l) parameters revealed by quasi-phase-matching (QPM) theory, our established theoretical model comprehensively characterizes both biophysical features of collagen dipoles and the crystalline characteristics of collagen fiber. This new model quantitatively reveals the 3-D distribution of second-harmonic generation (SHG) emission angle (?,J) in accordance with the emission power. Results show that fibrils diameter d1 and structural order m, which describes the structural characteristics of collagen fiber along the incident light propagation direction has significant influence on backward/forward SHG emission. The decrease of fibrils diameter d1 induces an increase of the peak SHG emission angle ?max. As d1 decreases to a threshold value, in our case it is around d1 = 150 nm when (m,l) = (1,0), ?max > 90 deg, indicating that backward SHG emission appears. The SHG may have two symmetrical emission distribution lobes or may have only one or two unsymmetrical emission lobes with unequal emission power, depending on the functional area of (m,l) on d1.

  6. Theoretical and experimental studies for high-repetition-rate disordered crystal lasers with harmonic self-mode locking.

    PubMed

    Sung, C L; Lee, C Y; Cho, H H; Huang, Y J; Chen, Y F; Pan, Z B; Yu, H H; Zhang, H J; Wang, J Y

    2016-02-22

    A harmonically self-mode-locked Nd:Sr3Y2(BO3)4 disordered crystal laser with subpicosecond pulse duration is demonstrated. We exploit the damped harmonic oscillator model to numerically verify that the mode spacing of the laser cavity can be modified to be the harmonics of the free spectral range of the Fabry-Perot cavity when the optical length of the laser cavity is close to a commensurate ratio of the optical length of the Fabry-Perot cavity. In experiment, the Fabry-Perot cavity can be formed by the pump facet of the disordered crystal and the front mirror. A 110 GHz single-pulse harmonically mode-locked pulse train with pulse duration of 857 fs is experimentally achieved under optical lengths of 27.19 and 4.08 mm for the laser cavity and Fabry-Perot cavity respectively, corresponding to a fractional number of 20/3. A maximum output power of 162 mW is obtained at an incident pump power of 3.1 W. PMID:26907036

  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. Dynamic single crystal to polycrystal transformation of a 1D-coordination polymer and its second harmonic generation.

    PubMed

    Cametti, Massimo; Bargigia, Ilaria; Mart-Rujas, Javier

    2016-01-19

    Upon guest CHCl3 release, the one-dimensional (1D) coordination polymer CHCl3 gives rise to a non-porous structure, , following a unit cell volume reduction of ca. 22%. Due to the considerable structural transformation, the single crystal does not maintain its integrity, and therefore the structure determination has been carried out by combining single crystal X-ray diffraction and ab initio X-ray powder diffraction analyses. The result shows a symmetry breaking transformation leading to an acentric crystalline material (), which shows nonlinear optical properties such as second harmonic generation. PMID:26700658

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Heckl, O. H.; Baer, C. R. E.; Krnkel, C.; Marchese, S. V.; Schapper, F.; Holler, M.; Sdmeyer, 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; Sdmeyer et al., Nat. Photonics 2:599, 2008; Rser 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. 3:270, 2007). The interaction between the laser pulses and the gas occurs in a Kagome-type Hollow-Core Photonic Crystal Fiber (HC-PCF) (Benabid et al., Science 298:399, 2002), which reduces the detection threshold for HHG to only 200 nJ. This novel type of fiber guides nearly all of the light in the hollow core (Couny et al., Science 318:1118, 2007), preventing damage even at intensities required for HHG. Our fiber guided 30-fs pulses with a pulse energy of more than 10 ?J, which is more than five times higher than for any other photonic crystal fiber (Hensley et al., Conference on Lasers and Electro-Optics (CLEO), IEEE Press, New York, 2008).

  11. Spatial-temporal structure of the femtosecond third harmonic generation in photonic-crystal fibers

    PubMed Central

    Kalashnikov, Vladimir L.; Sorokin, Evgeni; Sorokina, Irina T.

    2010-01-01

    We analyze the third harmonic generation by the supercontinuum at 1.5 μm in nonlinear-glass microstructured fibers. The numerical model includes the real field dynamics and allows analyzing the spectral as well as the temporal structure of the generated field. The calculated third harmonic and supercontinuum spectra are compared with the experiment in the SF6 glass PCF pumped by a femtosecond Cr4+:YAG oscillator. The spectral structure of the third harmonic is composed of the 10–20 high-order modes excited at the phase matching points around 500–550 nm. The individual third harmonic modes have spectral widths of 2–4 nm. In the time domain, the third harmonic signal is a ~10-ps pulse with ps-scale slow modulation, containing subpicosecond ripples at its trailing edge. PMID:19547487

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  13. 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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Kaltenbach, Andr; Schnau, Thomas; Lauritsen, Kristian; Trnkle, Gnther; 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.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  19. Influence of higher harmonics of the undulator in X-ray polarimetry and crystal monochromator design.

    PubMed

    Marx-Glowna, Berit; Schulze, Kai S; Uschmann, Ingo; Kämpfer, Tino; Weber, Günter; Hahn, Christoph; Wille, Hans Christian; Schlage, Kai; Röhlsberger, Ralf; Förster, Eckhart; Stöhlker, Thomas; Paulus, Gerhard G

    2015-09-01

    The spectrum of the undulator radiation of beamline P01 at Petra III has been measured after passing a multiple reflection channel-cut polarimeter. Odd and even harmonics up to the 15th order, as well as Compton peaks which were produced by the high harmonics in the spectrum, could been measured. These additional contributions can have a tremendous influence on the performance of the polarimeter and have to be taken into account for further polarimeter designs. PMID:26289265

  20. XTL Converter

    Energy Science and Technology Software Center (ESTSC)

    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

  1. XTL Converter

    SciTech Connect

    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.

  2. 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.

  3. 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. PMID:25969004

  4. Quasi-phase-matched second-harmonic Talbot self-imaging in a 2D periodically-poled LiTaO3 crystal.

    PubMed

    Liu, Dongmei; Wei, Dunzhao; Zhang, Yong; Zou, Jiong; Hu, X P; Zhu, S N; Xiao, Min

    2013-06-17

    We demonstrate the improved second-harmonic Talbot self-imaging through the quasi-phase-matching technique in a 2D periodically-poled LiTaO(3) crystal. The domain structure not only composes a nonlinear optical grating which is necessary to realize nonlinear Talbot self-imaging, but also provides reciprocal vectors to satisfy the phase-matching condition for second-harmonic generation. Our experimental results show that quasi-phase-matching can improve the intensity of the second-harmonic Talbot self-imaging by a factor of 21. PMID:23787586

  5. Characterization of Cholesterol Crystals in Atherosclerotic Plaques Using Stimulated Raman Scattering and Second-Harmonic Generation Microscopy

    PubMed Central

    Suhalim, JeffreyL.; Chung, Chao-Yu; Lilledahl, MagnusB.; Lim, RyanS.; Levi, Moshe; Tromberg, BruceJ.; Potma, EricO.

    2012-01-01

    Cholesterol crystals (ChCs) have been identified as a major factor of plaque vulnerability and as a potential biomarker for atherosclerosis. Yet, due to the technical challenge of selectively detecting cholesterol in its native tissue environment, the physiochemical role of ChCs in atherosclerotic progression remains largely unknown. In this work, we demonstrate the utility of hyperspectral stimulated Raman scattering (SRS) microscopy combined with second-harmonic generation (SHG) microscopy to selectively detect ChC. We show that despite the polarization sensitivity of the ChC Raman spectrum, cholesterol monohydrate crystals can be reliably discriminated from aliphatic lipids, from structural proteins of the tissue matrix and from other condensed structures, including cholesteryl esters. We also show that ChCs exhibit a nonvanishing SHG signal, corroborating the noncentrosymmetry of the crystal lattice composed of chiral cholesterol molecules. However, combined hyperspectral SRS and SHG imaging reveals that not all SHG-active structures with solidlike morphologies can be assigned to ChCs. This study exemplifies the merit of combining SRS and SHG microscopy for an enhanced label-free chemical analysis of crystallized structures in diseased tissue. PMID:22768956

  6. 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 (?), 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. PMID:23305871

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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 P21. 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 13C NMR, 1H 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 (?), thermal effusivity (e), thermal conductivity (k) and heat capacity (Cp) 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.

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

    DOEpatents

    Haas, Roger A. (Pleasanton, CA); Henesian, Mark A. (Livermore, CA)

    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.

  9. 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 ?m 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.

  10. Novel amino acid crystals for phase-matched second-harmonic generation: L-pyrrolidone-2-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Kitazawa, Manabu; Higuchi, Ryoichi; Takahashi, Mitsuo; Wada, Tatsuo; Sasabe, Hiroyuki

    1995-07-01

    A novel nonlinear optical amino acid derivative, L-pyrrolidone-2-carboxylic acid (L-PCA), has been studied for the application of UV generation by frequency upconversion of laser radiation. L-PCA is relatively easy to grow from solution to a large size, typically 402020 mm3, by a slow cooling method. This crystal is chemically stable because the crystal lattice is composed of a network of hydrogen-bonded molecules. L-PCA has a wide transparency extending to the UV region (the cutoff wavelength is 260 nm) and is therefore a good candidate for the second-harmonic generation (SHG) of Nd:YAG laser radiation (1064 nm). The nonlinear-optical coefficient d14 was measured to be 0.22 pm/V, and the measured phase-matching angles agreed with values calculated using refractive index data. The effective nonlinear optical coefficient deff of the type-I phase-matched SHG has also been measured to be 0.20 pm/V. UV generation down to 266 nm was achieved by phase-matched SHG in L-PCA crystals.

  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. PMID:25618055

  12. Temperature nonuniformity occurring during the cooling process of a KDP crystal and its effects on second-harmonic generation.

    PubMed

    Liang, Yingchun; Su, Ruifeng; Lu, Lihua; Liu, Haitao

    2014-08-10

    The temperature nonuniformity occurring during the cooling process of a KDP crystal is studied, along with its effects on the second-harmonic generation (SHG) of a high-average-power laser. A comprehensive model is proposed incorporating principles of thermodynamics, mechanics, and optics, and it is applied to investigate the temperature nonuniformity and its effects. The temperature rise caused by linear absorption is calculated, while the temperature nonuniformity occurring during the cooling process is analyzed using the finite-element method (FEM). The stress induced by the nonuniformity is then studied using the FEM, and the trend of its change is determined. Moreover, the changes in refractive index caused by the stress are calculated, the results of which are used to determine the variations in the induced phase mismatch. The SHG efficiency considering the phase mismatch is eventually obtained by solving the coupling wave equations. The results demonstrate that the temperature nonuniformity has negative effects on the SHG efficiency. PMID:25320918

  13. 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.

  14. Structural investigation of CuIn5Se8 single crystals by optical second harmonic generation, ellipsometry, and photoluminescence

    NASA Astrophysics Data System (ADS)

    Kulyuk, L.; Mirovitskii, V.; Arushanov, E.; Tezlevan, V.; Leon, M.; Mishina, E.; Sherstyuk, N.; Dumouchel, T.; Fortin, E.; Rasing, Th.

    2006-10-01

    CuIn5Se8 bulk single crystals were characterized using ellipsometry, photoluminescence (PL), and optical second harmonic generation (SHG). The refractive n(E ) and absorption k(E ) indices as functions of photon energy E are determined. The structure of the PL spectrum suggests the presence of the Cu-rich nonstoichiometric phases at the natural surfaces of the CuIn5Se8 sample. The best fit of the experimental SHG data is achieved by assuming that CuIn5Se8 belongs to the 4¯2m symmetry group. This result is in contradiction with x-ray analysis (6¯2m group), which testifies to the difference in surface and bulk structure.

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

    PubMed Central

    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. PMID:24156059

  16. Dual-bandgap hollow-core photonic crystal fibers for third harmonic generation.

    PubMed

    Montz, Z; Ishaaya, A A

    2015-01-01

    We present two novel hybrid photonic structures made of silica that possess two well-separated frequency bandgaps. The addition of interstitial air holes in a precise location and size allows these bandgaps to open with a ratio of ∼3 between their central frequencies at the air line ck(z)/w=1, thus fulfilling the basic guidance condition for third harmonic generation in hollow-core fibers. In addition, these designs may serve for high-power laser delivery of two well-separated wavelengths, such as visible and near infrared. PMID:25531607

  17. Resonant ensembles of stationary quasi-harmonic waves in one-dimensional crystals

    NASA Astrophysics Data System (ADS)

    Kovriguine, D. A.; Nikitenkova, S. P.

    2015-09-01

    Using a simple mathematical model, built on geometric representations of central and noncentral interactions between material particles in a one-dimensional anharmonic chain, nonlinear resonant interactions between quasi-harmonic waves are investigated in the so-called harmonic approximation. The investigation is carried out with standard asymptotic nonlinear dynamics methods. In the first-order approximation, resonant wave triads are established that are formed at a characteristic quadratic nonlinearity of the system provided that the phase-matching conditions are satisfied. It is demonstrated that the resonant triads can be of only three different types and each resonant triad can consist of only one longitudinal and two transverse oscillation modes. In the general case, a nontrivial interaction between different resonant triplets of three different types and spectral scales is implemented in a chain. Cascade processes of the energy exchange between oscillation modes are characterized by both the complicated dynamics typical of Hamiltonian nonintegrable dynamic systems and the presence of Lyapunov-stable multiwave steady-state motions. In ideal crystalline structures, such steady-state coherent wave ensembles can significantly affect the specific heat and other phenomenological parameters of a system, especially at low temperatures. Therefore, the theoretical and experimental study of these ensembles is of great importance.

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

    PubMed Central

    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

  19. Second harmonic generation of femtosecond radiation from a Cr:forsterite laser in a nonlinear-optical crystal at the plasma-formation threshold

    SciTech Connect

    Gordienko, V M; Dyakov, V A; Mikheev, P M; Syrtsov, V S

    2007-11-30

    The second harmonic generation in KDP and LiNbO{sub 3} crystals exposed to tightly focused radiation from a Cr:forsterite laser is studied. The negative influence exerted on this process by a plasma produced due to multiphoton ionisation in the focal region at laser pulse intensities above 10{sup 13} W cm{sup -2} is discussed. (nonlinear optical phenomena)

  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. Harmonic strain-optical response revealed in the isotropic (liquid) phase of liquid crystals

    NASA Astrophysics Data System (ADS)

    Kahl, P.; Baroni, P.; Noirez, L.

    2015-08-01

    A strong optical birefringence is observed when applying a small amplitude oscillatory strain to the liquid phase of a liquid crystal. This unpredicted birefringence is found to oscillate at the same frequency as the driving frequency, with frequencies down to 0.01 Hz. This birefringence is visible up to 15 C above the liquid crystal transition. This opto-dynamic property is interpreted as a result of a coupling of the orientational pretransitional fluctuations existing in the isotropic phase and long range elastic interactions recently identified in liquids. The conversion of the mechanical wave in an optical response is shapeable. Two examples of synchronized periodic signals are shown: the sine and the square waves. The optimization of the signal is analyzed using a Heaviside-step shear test. This optical property is immediately exploitable to design low energy on/off switching materials.

  3. Two-photon-absorption of frequency converter crystals at 248 nm

    NASA Astrophysics Data System (ADS)

    Divall, M.; Osvay, K.; Kurdi, G.; Divall, E. J.; Klebniczki, J.; Bohus, J.; Péter, Á.; Polgár, K.

    2005-12-01

    The two-photon-absorption coefficient of KDP, BBO, LTB, and CLBO crystals has been determined from the measurement of the intensity dependent transmission through long samples. The intensity of the sub-picosecond KrF excimer laser pulses on the samples was varied from 0.2-80 GW/cm2. The linear absorption of the samples was determined by using a low intensity, long pulse KrF laser. The first-principle simulations to the experimental data show a TPA value of 0.48 cm/GW for KDP, 0.5 cm/GW (o-ray) and 0.34 cm/GW (e-ray) in BBO, 0.22 cm/GW in LTB and 0.53 cm/GW in CLBO.

  4. Designing photonic quasi-crystal fibers of various folds: onto optimization of efficiency and bandwidth of second harmonic generation.

    PubMed

    Bhattacharjee, Ritapa; Senthilnathan, K; Sivabalan, S; Ramesh Babu, P

    2014-05-01

    We design photonic quasi-crystal fibers (PQFs) of six-, eight-, ten-, and twelve-folds for determining the optimized efficiency as well as the bandwidth of second harmonic generation (SHG). We report a maximum SHG relative efficiency of 941.36% W⁻¹ cm⁻² for a twelve-fold PQF of 2 μm pitch. The detailed numerical results reveal that, while the relative efficiency increases appreciably, the phase-matching bandwidth increases marginally, as and when the number of folds increases. As the primary interest of this work is to enhance the relative efficiency, we focus our analysis with a twelve-fold PQF for which the efficiency turns a maximum. In line with the practical feasibility of poling, we keep the pitch at 7 μm and report an optimized relative efficiency and phase-matching bandwidth as 95.28% W⁻¹ cm⁻² and 50.51 nm.cm, respectively. PMID:24921878

  5. 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.

  6. Enhancement in second harmonic generation efficiency, laser damage threshold and optical transparency of Mn 2+ doped L-alanine crystals: A correlation with crystalline perfection

    NASA Astrophysics Data System (ADS)

    Kushwaha, S. K.; Rathee, S. P.; Maurya, K. K.; Bhagavannarayana, G.

    2011-08-01

    Effect on crystalline perfection, second harmonic generation (SHG) efficiency, laser damage threshold (LDT) and optical transparency due to Mn 2+ doping in L-alanine crystals has been investigated. The crystalline perfection of pure and doped crystals was evaluated by high-resolution X-ray diffractometry, which revealed the improvement in the crystalline perfection at low and moderate doping concentrations. At moderate and high concentrations, the Mn 2+ ions were found to be incorporated predominantly at the interstitial sites of the crystalline matrix. The actual incorporated amount of dopants in the crystals was analyzed by atomic absorption spectroscopy. The optical transparency, SHG efficiency, and laser damage threshold of the grown crystals with different concentrations of Mn 2+ were investigated. From these studies it is revealed that Mn 2+ doping lead to a considerable enhancement in the measured nonlinear optical properties with a correlation on crystalline perfection.

  7. 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 %.

  8. Optical breakdown threshold in nanosecond high repetition second harmonic generation by periodically poled Mg-doped LiTaO{sub 3} crystal

    SciTech Connect

    Louchev, Oleg A.; Wada, Satoshi; Hatano, Hideki; Kitamura, Kenji

    2013-08-26

    Our study shows that a local temperature increase of ?1 K in the crystal lattice caused by second harmonic generation (SHG) and two-photon absorption of 532 nm radiation at the rear of periodically poled stoichiometric LiTaO{sub 3} crystal by changing spontaneous polarization induces a pyroelectric field ?10 kV/cm, accelerating free electrons to an energy of ?10 eV, followed by optical breakdown and crystal damage. Theoretical analysis leads to an explicit expression for the threshold laser fluence of optical breakdown giving ?1.2 J/cm{sup 2} for 1064 nm input radiation in 6.8 kHz pulsed SHG operation, agreeing well with the experimentally found value ?1.32 J/cm{sup 2}.

  9. Absolute non-linear optical coefficients measurements of CsLiB 6O 10 single crystals by second harmonic generation

    NASA Astrophysics Data System (ADS)

    Sifi, A.; Klein, R. S.; Maillard, A.; Kugel, G. E.; Péter, A.; Polgár, K.

    2003-10-01

    We present absolute measurements of the effective non-linear optical coefficients deff of cesium lithium borate crystals (CsLiB 6O 10, CLBO) by second harmonic generation using a continuous Nd-YAG laser source. The experiments were carried out at room temperature, on crystals cut perpendicular to type I or type II phase matching directions, with two different crystal lengths along the propagation direction. The d36 and d14 non-linear coefficients involved in deff developments are deduced and are shown to be equal as it is predicted by the Kleinman symmetry. Two different compositions prepared by the Czochralski technique from melt with compositions of 1:1:6 and 1:1:5.5 molar ratios of Cs 2O, Li 2O and B 2O 3 are comparatively studied.

  10. 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.

  11. Quaternionic Harmonic Analysis of Texture

    Energy Science and Technology Software Center (ESTSC)

    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.

  12. 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.

  13. 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.

  14. 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).

  15. Broadband dynamic phase matching of high-order harmonic generation by a high-peak-power soliton pump field in a gas-filled hollow photonic-crystal fiber.

    PubMed

    Serebryannikov, Evgenii E; von der Linde, Dietrich; Zheltikov, Aleksei M

    2008-05-01

    Hollow-core photonic-crystal fibers are shown to enable dynamically phase-matched high-order harmonic generation by a gigawatt soliton pump field. With a careful design of the waveguide structure and an appropriate choice of input-pulse and gas parameters, a remarkably broadband phase matching can be achieved for a soliton pump field and a large group of optical harmonics in the soft-x-ray-extreme-ultraviolet spectral range. PMID:18451958

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

    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.

  18. 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.

  19. Impact of stray capacitance on hvdc harmonics

    SciTech Connect

    Larsen, E.V.; Sublich, M.; Kapoor, S.C.

    1989-01-01

    Recent experience suggests that a new approach is needed to determining harmonic generation from hvdc converters for the purpose of telephone interference evaluation. This paper presents simulation results showing the effect on harmonic generation of stray capacitances inherent to hvdc converters. These simulation results illustrate the basic characteristics of the phenomenon, which agree qualitatively with field experience.

  20. Nonlinear single-crystal fibers of undoped or Nd 3+-doped niobates: growth by LHPG, spectroscopy and second harmonic generation

    NASA Astrophysics Data System (ADS)

    Foulon, Gisle; Ferriol, Michel; Brenier, Alain; Cohen-Adad, Marie-Thrse; Boudeulle, Micheline; Boulon, Georges

    1997-07-01

    The renewal of second order non-linear crystals is very strong in laser materials optics. We are involved in the search of new systems based upon the highly non-linear niobate crystal family. Among these crystals, Ba 2NaNb 5O 15 (BNN) and K 3Li 2- xNb 5+ xO 15+2 x (KLN, 0.15 < x < 0.5) with a tungsten bronze-type structure are very efficient materials for the obtention of, respectively, green and blue laser light by frequency doubling or by self-frequency doubling after doping by Nd 3+ ions. Unfortunately, BNN and KLN are difficult to grow by conventional techniques such as Czochralski without cracks caused by a strong lattice change occurring during cooling of the crystals. In addition, microtwins in BNN crystals and compositional inhomogeneities in KLN ones are often encountered. The obtention of good quality and crackless BNN and KLN single crystals doped with different amounts of Nd 2O 3 is reported. The crystals were grown by the laser heated pedestal growth (LHPG) technique. This method allowed to obtain good quality and homogeneous crystals of BNN and KLN overcoming the problems encountered with other growth techniques. More particularly, for BNN crystals, a structural transition between orthorhombic (space group: Pba2) and tetragonal symmetry (space group: P4bm) was found to occur for a Nd 3+ amount between 2 and 3 at% avoiding the microtwinning which disturbs the optical properties of the crystals. Low temperature spectroscopy revealed that Nd 3+ ions substitute both Ba 2+ and Na + ions in the pentagonal and square sites of the tungsten bronze-type structure of BNN whereas they substitute only K + ions in the pentagonal sites of that of KLN. Non-critical phase matching at room temperature was also investigated for both materials.

  1. crystal

    NASA Astrophysics Data System (ADS)

    Bai, Fen; Wang, Qingpu; Tao, Xutang; Li, Ping; Zhang, Xingyu; Liu, Zhaojun; Shen, Hongbin; Lan, Weixia; Gao, Liang; Gao, Zeliang; Zhang, Junjie; Fang, Jiaxiong

    2014-08-01

    An eye-safe Raman laser is realized with BaTeMo2O9 (BTM) nonlinear crystal for the first time. By using a diode-end-pumped acousto-optically Q-switched Nd:YVO4 laser as the pumping source, the BTM crystal converts the fundamental laser at 1,342 nm to first-Stokes laser at 1,531 nm successfully. With an incident power of 10.8 W and a pulse repetition rate of 25 kHz, the average output power at 1,531 nm is obtained to be 0.83 W, corresponding to a diode-to-Stokes conversion efficiency of 7.7 %. The pulse width is 11 ns, and the peak power is 3.0 kW.

  2. Strong second harmonic generation in SiC, ZnO, GaN two-dimensional hexagonal crystals from first-principles many-body calculations.

    PubMed

    Attaccalite, C; Nguer, A; Cannuccia, E; Grning, M

    2015-04-14

    The second harmonic generation (SHG) intensity spectrum of SiC, ZnO, GaN two-dimensional hexagonal crystals is calculated by using a real-time first-principles approach based on Green's function theory [Attaccalite et al., Phys. Rev. B: Condens. Matter Mater. Phys. 2013 88, 235113]. This approach allows one to go beyond the independent particle description used in standard first-principles nonlinear optics calculations by including quasiparticle corrections (by means of the GW approximation), crystal local field effects and excitonic effects. Our results show that the SHG spectra obtained using the latter approach differ significantly from their independent particle counterparts. In particular they show strong excitonic resonances at which the SHG intensity is about two times stronger than within the independent particle approximation. All the systems studied (whose stabilities have been predicted theoretically) are transparent and at the same time exhibit a remarkable SHG intensity in the range of frequencies at which Ti:sapphire and Nd:YAG lasers operate; thus they can be of interest for nanoscale nonlinear frequency conversion devices. Specifically the SHG intensity at 800 nm (1.55 eV) ranges from about 40-80 pm V(-1) in ZnO and GaN to 0.6 nm V(-1) in SiC. The latter value in particular is 1 order of magnitude larger than values in standard nonlinear crystals. PMID:25766901

  3. Improvement and formation of UV-induced damage on LBO crystal surface during long-term high-power third-harmonic generation.

    PubMed

    Hong, Hailong; Liu, Qiang; Huang, Lei; Gong, Mali

    2013-03-25

    We demonstrate the improvement and formation of UV-induced damage on LBO crystal output surface during long-term (130 h) high-power (20 W) high-repetition-rate (80 kHz) third-harmonic generation. The output surface was super-polished (RMS surface roughness <0.6 nm) to sub-nanometer scale super smooth roughness. The surface lifetime has been improved more than 20-fold compared with the as-polished ones (RMS surface roughness 4.0~8.0 nm). The damage could be attributed to the consequence of thermal effects resulted from impurity absorptions. Simultaneously, it was verified that the impurities originated in part from the UV-induced deposition. PMID:23546112

  4. Second-harmonic generation in a laterally azo-bridged trimer ferroelectric liquid crystal: Phase matching in the presence of a helicoidal structure

    NASA Astrophysics Data System (ADS)

    Etxebarria, J.; Ortega, J.; Folcia, C. L.; Zhang, Y.; Walker, C.

    2012-11-01

    Optical second-harmonic generation (SHG) has been studied in a trimer smectic C* liquid crystal especially designed for nonlinear optical applications. The molecule has a long conjugated donor-acceptor unit that transversally links three parallel rod-shaped moieties. A strong SHG signal has been observed at a fundamental wavelength of 1369 nm even in the presence of the spontaneous helicoidal structure of the smectic C* phase. This unusual behavior has been interpreted as due to the existence of phase matching, in which the wave vector mismatch is compensated by the wave vector of the helix. This point has been confirmed by the study of the SHG intensity versus sample thickness and light polarization characteristics. The main coefficient of the second-order susceptibility tensor of the material has been estimated to be d22=28 pm/V.

  5. Second-harmonic generation in a laterally azo-bridged trimer ferroelectric liquid crystal: phase matching in the presence of a helicoidal structure.

    PubMed

    Etxebarria, J; Ortega, J; Folcia, C L; Zhang, Y; Walker, C

    2012-11-01

    Optical second-harmonic generation (SHG) has been studied in a trimer smectic C* liquid crystal especially designed for nonlinear optical applications. The molecule has a long conjugated donor-acceptor unit that transversally links three parallel rod-shaped moieties. A strong SHG signal has been observed at a fundamental wavelength of 1369 nm even in the presence of the spontaneous helicoidal structure of the smectic C* phase. This unusual behavior has been interpreted as due to the existence of phase matching, in which the wave vector mismatch is compensated by the wave vector of the helix. This point has been confirmed by the study of the SHG intensity versus sample thickness and light polarization characteristics. The main coefficient of the second-order susceptibility tensor of the material has been estimated to be d(22) = 28 pm/V. PMID:23214805

  6. 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. PMID:26258387

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

    PubMed

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

    2015-10-01

    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. PMID:26520949

  8. 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 Ф80 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  10. a Study of New Optical Materials. I. Crystal-Chemical Development of New Optical Frequency Converters. I. New Hosts for Chromium

    NASA Astrophysics Data System (ADS)

    Schaffers, Kathleen Irene

    The emphasis of this work has been in two areas of optical materials--the crystal-chemical development of new optical frequency converters and the synthesis and study of the new hosts for Cr^{3+} luminescence and lasing. A simple method has been developed to identify promising frequency-doubling materials containing triangular oxoanions by estimation of nonlinear susceptibilities. Implementation of this method and its results have generated predictive capabilities in determining the relationships among crystal structure, nonlinear properties, and threshold powers. The new noncentrosymmetric borate SrLiB_9O _{15} is discussed; its structure is built from a 3-dimensional condensation of B_3O_7 units with channels alternately filled with Sr and Li atoms. From these studies, a prescription for new pyroborate frequency converters has been developed. The material CdCl _2C_3H_7 NO_2, has been synthesized and structurally characterized by single-crystal X-ray diffraction. Three new alkaline-earth beryllium borates, built from unique 2- and 3-dimensional networks and frameworks, have been identified. The structure of SrBe_2 (BO_3)_2 consists of layers of composition (Be_2(BO _3)_2]^{2- } interleaved by Sr atoms. CaBeB_2 O_5 is constructed from a CaO_9 polyhedral network and a beryllium borate network. In BaBe_2(BO _3)_2 the structure is composed of a beryllium borate framework intermingled with a Ba-centered dodecahedral framework. Several materials with potential as hosts for Cr^{3+} lasing have been analyzed. The structural study of the laser host LiSrAlF _6 revealed the distortions at the Al site that contribute to the unique optical properties of the Cr^{3+}-doped crystals. The family of solid state oxide A_6MM ^'(BO_3) _6 is one of the largest families of oxide reported to date. Metal site preferences, disorder, solid solubility, and the interrelationship between this structure and the layered structure type of Ba_3Sc(BO _3)_3 are detailed. An optimal synthetic procedure has been developed for these materials to provide pure, highly crystalline phases. Also, the structural and optical features of (Cr^ {3+}:) Sr_3In(BO _3)_3 with A = Sr and M = M^' = In have been studied. The material Sr_2LiInB _4O_{10}, was discovered while searching for a suitable lithium borate flux for crystal growth of the compound Sr _3In(BO_3)_3..

  11. Role of Acentric Displacements on the Crystal Structure and Second-Harmonic Generating Properties of RbPbCO3F and CsPbCO3F

    PubMed Central

    2015-01-01

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet–visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6̅m2 (crystal class 6̅m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even–odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb2+. The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

  12. Crystal growth of four oxovanadium(IV) tartrates prepared via a mild two-step hydrothermal method: observation of spin-dimer behavior and second harmonic generation.

    PubMed

    Cortese, Anthony J; Wilkins, Branford; Smith, Mark D; Yeon, Jeongho; Morrison, Gregory; Tran, T Thao; Halasyamani, P Shiv; zur Loye, Hans-Conrad

    2015-04-20

    Four new oxovanadium(IV) tartrates, namely, A2[(VO)2(C4H4O6)(C4H2O6)(H2O)2](H2O)2, where A = Cs, 1, Rb, 2; K2[(VO)2(C4H2O6)2(H2O)2](H2O)2, 3; and Na2[(VO)2(C4H4O6)(C4H2O6)(H2O)7](H2O)2, 4, were prepared utilizing a two-step, mild hydrothermal route involving l-(+)-tartaric acid as the reducing agent. All four compounds were structurally characterized by single-crystal and powder X-ray diffraction methods and were found to crystallize in the non-centrosymmetric orthorhombic space groups P212121 for 1, 2, and 4 and C2221 for 3. The temperature dependence of the magnetic susceptibility of these compounds was measured, and 1, 2, and 4 were found to be paramagnetic down to 2 K, while 3 was found to exhibit spin-dimer behavior. Compounds 1, 2, and 3 were found to be second harmonic generation active. All compounds were further characterized by IR and UV-vis spectroscopies. PMID:25823416

  13. Second-harmonic generation studies in the B2 and B4 phases of a banana-shaped liquid crystal

    NASA Astrophysics Data System (ADS)

    Ortega, J.; Pereda, N.; Folcia, C. L.; Etxebarria, J.; Ros, M. B.

    2001-01-01

    Second-harmonic generation (SHG) measurements have been performed in the B2 phase of the achiral banana-shaped molecule with n=12 alkoxy end chains (P-12-O-PIMB). A quantitative value of the nonlinear efficiency has been obtained from SHG curves at oblique incidences, taking into account that the signal is generated by a random orientation of different domains. In the B4 phase, circular dichroism, optical absorption and SHG studies have been carried out. It has been found that there are no simple helical arrangements giving rise to selective reflection in the visible region of the spectrum. In addition, some unusual features of the SHG behavior are pointed out. It is concluded that the phase is intrinsically inactive for the SHG process. The detected signal is due to the presence of some birefringent inclusions that are created at the B2 to B4 transition and slowly disappear while the sample is maintained within the B4 phase. A structural model for these inclusions is presented.

  14. Optical properties of the second harmonic generation for nonlinear crystal CsLiB6O10

    NASA Astrophysics Data System (ADS)

    Wang, Li; Chen, Shaohua; Xue, Jianhua; Men, Yanbin

    2001-11-01

    According to Sellmeier equation, the detailed theoretical study using a computer stimulation on the nonlinear optical properties of CLBO (CsLiB6O10) frequency doubling are presented as compared to that of BBO in type I and type II phase matching (PM). We obtained the advantage of both a large acceptance angle and a small effective nonlinear coefficient of CLBO versus BBO. The curves of the effective nonlinear coefficient, phase matching angle, walk- off angle, permitted angle and wavelength versus the fundamental wavelength and SHG conversion efficiency versus the crystal length are plotted according to the formulas we derived in type I and type II from the PM. The theoretical guiding to experiments band application in CLBO is presented.

  15. Discriminating harmonicity

    NASA Astrophysics Data System (ADS)

    Kidd, Gerald; Mason, Christine R.; Brughera, Andrew; Chiu, Chung-Yiu Peter

    2003-08-01

    Simultaneous tones that are harmonically related tend to be grouped perceptually to form a unitary auditory image. A partial that is mistuned stands out from the other tones, and harmonic complexes with different fundamental frequencies can readily be perceived as separate auditory objects. These phenomena are evidence for the strong role of harmonicity in perceptual grouping and segregation of sounds. This study measured the discriminability of harmonicity directly. In a two interval, two alternative forced-choice (2I2AFC) paradigm, the listener chose which of two sounds, signal or foil, was composed of tones that more closely matched an exact harmonic relationship. In one experiment, the signal was varied from perfectly harmonic to highly inharmonic by adding frequency perturbation to each component. The foil always had 100% perturbation. Group mean performance decreased from greater than 90% correct for 0% signal perturbation to near chance for 80% signal perturbation. In the second experiment, adding a masker presented simultaneously with the signals and foils disrupted harmonicity. Both monaural and dichotic conditions were tested. Signal level was varied relative to masker level to obtain psychometric functions from which slopes and midpoints were estimated. Dichotic presentation of these audible stimuli improved performance by 3-10 dB, due primarily to a release from ``informational masking'' by the perceptual segregation of the signal from the masker.

  16. 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.

  17. Harmonics and Resonance Issues with Wind Plants

    SciTech Connect

    Bradt, M.; Badrzadeh, Babak; Camm, E H; Castillo, Nestor; Mueller, David; Siebert, T.; Schoene, Jens; Smith, Travis M; Starke, Michael R; Walling, R.

    2011-01-01

    Wind plants are susceptible to lightly-damped resonances which can attract and amplify ambient grid harmonic distortion and magnify wind turbine harmonic generation. Long-accepted harmonic modeling assumptions and practices are not appropriate for wind plants. VSCs are not ideal current sources and grid impedance is important. Attention to modeling detail and thorough evaluation over range of conditions is critical to meaningful analysis. In general, wind turbines are very slight sources of harmonics. Most harmonic issues are a result of resonance, caused by capacitor banks (for reactive power compensation) or from the extensive underground cabling in a collector system. Converter controls instability can be exacerbated by power system resonances. In some cases this has caused severe voltage distorDon and other problems. The IEEE 519 recommended guidelines are very restrictive. I recommend that they are used to resolve serious harmonic issues, and not to create petty problems.

  18. 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.

  19. Sellmeier equation and conversion of the radiation of a repetitively pulsed tunable TEA CO{sub 2} laser into the second harmonic in a ZnGeP{sub 2} crystal

    SciTech Connect

    Zakharov, S V; Negin, A E; Filippov, P G; Zhilis, E F

    1999-09-30

    The results are reported of measurements of the spectral dependences of the conversion efficiency and of the phase-matching angles in the conversion of the radiation of a repetitively pulsed TEA CO{sub 2} laser into the second harmonic in ZnGeP{sub 2} crystals. The measured angular phase-matching curves are compared in the range 9.2 - 10.8 {mu}m with curves calculated, on the basis of the spectral dependences of the refractive indices for the ordinary and extraordinary waves, for several Sellmeier coefficients. The Sellmeier coefficients are in agreement with the measured values. (nonlinear optical phenomena)

  20. Coherent combining of fiber-laser-pumped frequency converters using all fiber electro-optic modulator for active phase control

    NASA Astrophysics Data System (ADS)

    Bourdon, P.; Durcu, A.; Canat, G.; Le Gout, J.; Goular, D.; Lombard, L.

    2015-03-01

    Coherent beam combining (CBC) by active phase control could be useful for power scaling fiber-laser-pumped optical frequency converters like OPOs. However, a phase modulator operating at the frequency-converted wavelength is needed, which is non standard component. Fortunately, nonlinear conversion processes rely on a phase-matching condition correlating, not only the wave vectors of the coupled waves, but also their phases. This paper demonstrates that, using this phase correlation for indirect control of the phase, coherent combining of optical frequency converters is feasible using standard all-fibered electro-optic modulators. For the sake of demonstration, this new technique is experimentally applied twice for continuous wave second-harmonic-generator (SHG) combination: i) combining 2 SHG of 1.55-?m erbium-doped fiber amplifiers in PPLN crystals generating 775-nm beams; ii) combining 2 SHG of 1.064-?m ytterbium-doped fiber amplifiers in LBO crystals generating 532-nm beams. Excellent CBC efficiency is achieved on the harmonic waves in both these experiments, with ?/20 and ?/30 residual phase error respectively. In the second experiment, I/Q phase detection is added on fundamental and harmonic waves to measure their phase variations simultaneously. These measurements confirm the theoretical expectations and formulae of correlation between the phases of the fundamental and harmonic waves. Unexpectedly, in both experiments, when harmonic waves are phase-locked, a residual phase difference remains between the fundamen tal waves. Measurements of the spectrum of these residual phase differences locate them above 50 Hz, revealing that they most probably originate in fast-varying optical path differences induced by turbulence and acoustic-waves on the experimental breadboard.

  1. 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.

  2. Poling-induced crystallization of tetragonal BaTiO3 and enhancement of optical second-harmonic intensity in BaO-TiO2-TeO2 glass system

    NASA Astrophysics Data System (ADS)

    Narazaki, Aiko; Tanaka, Katsuhisa; Hirao, Kazuyuki

    1999-11-01

    Effect of poling on surface crystallization behavior of BaTiO3 in 15BaO-15TiO2-70TeO2 glass and on second-harmonic generation of the resultant glass ceramics has been examined. A direct current voltage in a range of 0.3-1 kV was applied to the original glass at around 400 C, which is above its glass transition temperature, followed by cooling of the sample to room temperature with the voltage kept constant. X-ray diffraction patterns indicate that the poling increased the fraction of crystalline phases precipitated at the glass surface and that BaTiO3 crystallites were precipitated preferentially with (101)- or (110)-orientation. It is also observable that the x-ray diffraction line assigned to BaTiO3 shifted from the position corresponding to bulk cubic crystal to that of ferroelectric tetragonal one when the applied voltage was increased. In other words, the poling treatment stabilizes the tetragonal BaTiO3 phase, leading to a larger optical second-order nonlinear susceptibility. In fact, the second-harmonic intensity for the glass ceramic poled at 420 C was enhanced by a factor of ten compared with the glass ceramic heat treated without an external electric field.

  3. Harmonic engine

    DOEpatents

    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.

  4. Power converter

    NASA Technical Reports Server (NTRS)

    Black, J. M. (Inventor)

    1981-01-01

    A dc-to-dc converter employs four transistor switches in a bridge to chop dc power from a source, and a voltage multiplying diode rectifying ladder network to rectify and filter the chopped dc power for delivery to a load. The bridge switches are cross coupled in order for diagonally opposite pairs to turn on and off together using RC networks for the cross coupling to achieve the mode of operation of a free running multivibrator, and the diode rectifying ladder is configured to operate in a push-pull mode driven from opposite sides of the multivibrator outputs of the ridge switches. The four transistor switches provide a square-wave output voltage which as a peak-to-peak amplitude that is twice the input dc voltage, and is thus useful as a dc-to-ac inverter.

  5. Compact, harmonic multiplying gyrotron amplifiers

    SciTech Connect

    Guo, H.Z.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Tate, J.; Chen, S.H.

    1995-12-31

    A compact, harmonic multiplying gyrotron traveling wave amplifier is being developed. The device is a three-stage tube with the output section running as a fourth harmonic gyro-TWT, the input section running as a fundamental gyro-TWT, and the middle operating at the second harmonic of the cyclotron frequency. Radiation is suppressed by servers between the sections. The operating beam of the tube is produced by a magnetron injection gun (MIG). A TE{sub 0n} mode selective interaction circuit consisting of mode converters and a filter waveguide is employed for both input and output sections to solve the mode competition problem, which is pervasive in gyro-TWT operation. The input section has an input coupler designed as a TE{sub 0n} mode launcher. It excites a signal at the fundamental cyclotron frequency (17.5 GHz), which is amplified in the first TWT interaction region. So far the device is similar to a two-stage harmonic gyro-TWT. The distinction is that in the three-stage device the second section will be optimized not for output power but for fourth harmonic bunching of the beam. A gyroklystron amplifier has also been designed. The configuration is similar to the gyro-TWT but with the traveling wave interaction structures replaced by mode selective special complex cavities. Cold test results of the wideband input coupler and the TE{sub 0n} mode selective interaction circuit have been obtained.

  6. Wiggler magnetic field assisted second harmonic generation in clusters

    NASA Astrophysics Data System (ADS)

    Aggarwal, Munish; Vij, Shivani; Kant, Niti

    2015-06-01

    Wiggler magnetic field assisted second harmonic generation in clusters has been investigated theoretically. An intense short-pulse laser propagating through a gas embedded with atomic clusters, converts it into hot plasma balls. For clusters with radius less than one tenth of the laser wavelength, the nonlinear restoration force dominates, which leads to second harmonic generation. The magnetic wiggler provides the uncompensated momentum to second harmonic photon, to make the process of harmonic generation resonant. We explore the impact of laser intensity and cluster size on the efficiency of second harmonic generation. Pulse slippage of second harmonic pulse out of the domain of fundamental laser pulse has been observed on account of group velocity mismatch between the fundamental and second harmonic pulse. Enhancement in the efficiency of the second harmonic is seen for the optimum values of wiggler magnetic field.

  7. A new real-time non-coherent to coherent light image converter - The hybrid field effect liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Grinberg, J.; Jacobson, A.; Bleha, W.; Miller, L.; Fraas, L.; Boswell, D.; Myer, G.

    1975-01-01

    A new, high-performance device has been developed for application to real-time coherent optical data processing. The new device embodies a CdS photoconductor, a CdTe light-absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The noncoherent image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the ac voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state and the optical birefringence effect to create the bright on-state. The liquid crystal modulates the polarization of the coherent read-out light so an analyzer must be used to create an intensity modulated output beam.

  8. 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.

  9. 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.

  10. Nonlinear single-crystal fibers of undoped and rare earth-doped niobates: growth by LHPG, spectroscopy and second harmonic generation

    NASA Astrophysics Data System (ADS)

    Foulon, Gisele; Ferriol, Michel; Brenier, Alain; Cohen-Adad, Marie-Therese; Boulon, Georges

    1997-11-01

    The renewal of second order non-linear crystals is very strong in laser materials optics. We are involved in the search of new systems based upon highly non-linear niobate crystal family. Among these crystals, Ba2NaNb5O15 (BNN) and K3Li2-xNb5+xO15+2x (KLN, 0.15 < x < 0.5) with a tungsten bronze-type structure are very efficient materials for the obtention of respectively green and blue laser light by frequency doubling or by self-frequency doubling after doping by Nd3+ ions. Unfortunately, BNN and KLN are difficult to grow by conventional techniques such as Czochralski without cracks caused by a strong lattice change occurring during cooling of the crystals. In addition, microtwins in BNN crystals and compositional inhomogeneities in KLN ones are often encountered. The obtention of good quality and crackless BNN and KLN single crystals doped with different amounts of Nd2O3 is reported. The crystals were grown by the laser heated pedestal growth technique. This method allowed to obtain good quality and homogeneous crystals of BNN and KLN overcoming the problems encountered with other growth techniques. More particularly, for BNN crystals, a structural transition between orthohombic and tetragonal symmetry was found to occur for a Nd3+ amount between 2 and 3 atomic percent avoiding the microtwinning which disturbs the optical properties of the crystals. Low temperature spectroscopy revealed that Nd3+ ions substitute both Ba2+ and Na+ ions in the pentagonal and square sites of the tungsten bronze-type structure of BNN whereas they substitute only K+ ions in the pentagonal sites of that of KLN. Non- critical phase matching at room temperature was also investigated for both materials.

  11. High energy second-harmonic generation of Nd:glass laser radiation with large aperture CsLiB6O10 crystals

    NASA Astrophysics Data System (ADS)

    Kiriyama, Hiromitsu; Inoue, Norihiro; Yamakawa, Koichi

    2002-09-01

    We have demonstrated the generation of a high-energy green laser pulse using large aperture CsLiB6O10 (CLBO) crystals for the first time to our knowledge. A pulsed energy of 25 J at 532-nm was generated using the 1064-nm incident Nd:glass laser radiation with an energy of 34 J. High conversion efficiency of 74 % at intensities of only 370 MW/cm2 was obtained using a two-stage crystal architecture. This result represents the highest green pulse energy ever reported using the CLBO crystals.

  12. High energy second-harmonic generation of Nd:glass laser radiation with large aperture CsLiB6O10 crystals.

    PubMed

    Kiriyama, Hiromitsu; Inoue, Norihiro; Yamakawa, Koichi

    2002-09-23

    We have demonstrated the generation of a high-energy green laser pulse using large aperture CsLiB6O10 (CLBO) crystals for the first time to our knowledge. A pulsed energy of 25 J at 532-nm was generated using the 1064-nm incident Nd:glass laser radiation with an energy of 34 J. High conversion efficiency of 74 % at intensities of only 370 MW/cm2 was obtained using a two-stage crystal architecture. This result represents the highest green pulse energy ever reported using the CLBO crystals. PMID:19451960

  13. Power system applications for PASC converter systems

    SciTech Connect

    Donnelly, M.K.; Johnson, R.M.

    1994-04-01

    This paper shows, using computer EMTP simulations, some preliminary results of applying pulse amplitude synthesis and control (PASC) technology to single-source level voltage converter system. The method can be applied to any single terminal pair source with appropriate modifications in power extraction interface and computer control program to match source and load impedance characteristics. The PASC realization as discussed here employs banks of transformers, one bank per phase, in which the primaries are connected in parallel through a switch matrix to the dc source. Two opposite polarity primaries per transformer are pulsed alternatively in time to produce an oscillatory sinusoidal output waveform. PASC conversion system capabilities to produce both leading and lagging power factor power output in single-phase and three-phase {Delta} or Y configurations are illustrated. EMTP simulations are used to demonstrate the converter capabilities. Also included are discussions regarding harmonics and potential control strategies to adapt the converter to an application or to minimize harmonics.

  14. Frequency mixing crystal

    DOEpatents

    Ebbers, Christopher A. (Livermore, CA); Davis, Laura E. (Manteca, CA); Webb, Mark (Salida, CA)

    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.

  15. A harmonic rejection scheme for X-ray monochromators

    NASA Astrophysics Data System (ADS)

    Jach, Terrence; Kirkland, J. P.; Wolf, P. D.; Neiser, R. A.

    1987-06-01

    X-ray monochromators based on the diffraction of the radiation from crystals suffer from the fact that higher orders of diffraction are always possible. We have implemented a scheme for a double-crystal monochromator used with synchrotron radiation which eliminates this problem to a selectable degree. Using two detectors with different sensitivities to the fundamental and harmonic radiation in the second crystal ac feedback loop, we are able to discriminate against the harmonic radiation, even while scanning the monochromator in energy.

  16. Spectroscopic investigation, nucleation, growth, optical, thermal and second harmonic studies of novel semi-organic nonlinear optical crystal - thiourea urea zinc sulfate.

    PubMed

    Rao, Redrothu Hanumantha; Kalainathan, S

    2012-11-01

    A new nonlinear optical crystal thiourea urea zinc sulfate (TUZS) has been grown by slow evaporation technique in equimolar ratio. Solubility and metastable zone width measurements have been determined for the grown crystal. Single crystal XRD revealed that the crystal system belongs to orthorhombic with cell parameters a=7.78, b=11.15 and c=15.47. The sharp and well defined Bragg peaks observed in the powder XRD pattern confirm the crystalline nature of the TUZS compound. The grown mechanism and surface features were investigated by optical microscopic techniques such as scanning electron microscopy (SEM). The presence of zinc in the grown crystal was detected by atomic absorption spectroscopy and EDAX analysis. The compound has been confirmed by (1)H NMR, mass and FTIR spectral studies. The transmittance spectrum of TUZS has been used to calculate the extinction coefficient K, reflectance R, as functions of photon energy. The optical band gap of TUZS is 4.046 eV. The SHG efficiency has been tested by the Kurtz powder technique using Nd: YAG laser and KDP sample has been used as a standard reference material. PMID:22820345

  17. Second-harmonic generation in transparent surface crystallized glasses in the BaO-B{sub 2}O{sub 3}-TeO{sub 2} system

    SciTech Connect

    Murugan, G. Senthil; Suzuki, Takenobu; Ohishi, Yasutake; Takahashi, Yoshihiro; Benino, Yasuhiko; Fujiwara, Takumi; Komatsu, Takayuki

    2004-10-18

    A transparent glass-ceramic containing borate crystallites in tellurite glass is reported. Controlled heat treatment resulted in surface crystallization of BaB{sub 4}O{sub 7} in the BaO-B{sub 2}O{sub 3}-TeO{sub 2} glass system. The second-order optical nonlinearities observed in these surface crystallized glasses were attributed to the distortion present in the BaB{sub 4}O{sub 7} unit cell as evidenced by x-ray powder diffraction studies. A d{sub 33} value of 0.08 pm/V was obtained from the Maker fringe analysis for a surface crystallized glass.

  18. Frequency converter design and manufacturing considerations for the National Ignition Facility

    SciTech Connect

    Hibbard, R.L.; English, R.E., Jr.; De Yoreo, J.J.; Montesanti, R.C.

    1998-03-25

    The National Ignition Facility (NIF), being constructed at Lawrence Livermore National Laboratory (LLNL), comprises 192 laser beams, Figure 1. 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}=0.35). On NIF the frequency conversion crystals are part of the Final Optics Assembly (FOA), whose two principal functions are to convert the laser light to 3{omega} and focus it on target. In addition, the FOA provides a vacuum window to the target chamber, smoothes the on- target irradiance profile, moves the unconverted light away from the target, and provides signals for alignment and diagnostics. The FOA has four Integrated Optics Modules (IOM), Figure 4, each of which contains two 41 cm square crystals are mounted with the full edge support to micro radian angular and micron flatness tolerances. This paper is intended to be an overview of the important factors that affect frequency conversion on NIF. Chief among these are angular errors arising from crystal growth, finishing, and mounting. The general nature of these errors and how they affect frequency conversion, and finally the importance of a frequency conversion metrology tool in assessing converter performance before opto-mechanical assemblies are installed on NIF will be discussed.

  19. Numerical Analysis of Fifth-Harmonic Conversion of Low-Power Pulsed Nd:YAG Laser with Resonance of Second Harmonic

    NASA Astrophysics Data System (ADS)

    Chang, Lien-Bee; Wang, S. C.; Kung, A. H.

    2003-07-01

    A model for the fifth-harmonic generation of pulsed IR lasers involving an external ring cavity resonating at the second harmonic has been developed. Numerical analysis is performed to show the relative effects of the pulse delay, input polarization, and orientation of the nonlinear crystals on the fifth harmonic power. The results are validated by published experimental results. The model is used to analyze and obtain the optimal combination of nonlinear optical crystals for the fifth-harmonic generation. Our calculation shows that the combination of LiB3O5 (LBO), CsLiB6O10 (CLBO), and CLBO crystals for the second-harmonic, fourth-harmonic, and fifth-harmonic generation steps respectively gives an approximate conversion of 30% from the fundamental to the fifth harmonic power, resulting in 2 W at 213 nm for an input of 7 W at 1064 nm.

  20. 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.

  1. 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.

  2. 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

  3. Harmonic analysis of spacecraft power systems using a personal computer

    NASA Technical Reports Server (NTRS)

    Williamson, Frank; Sheble, Gerald B.

    1989-01-01

    The effects that nonlinear devices such as ac/dc converters, HVDC transmission links, and motor drives have on spacecraft power systems are discussed. The nonsinusoidal currents, along with the corresponding voltages, are calculated by a harmonic power flow which decouples and solves for each harmonic component individually using an iterative Newton-Raphson algorithm. The sparsity of the harmonic equations and the overall Jacobian matrix is used to an advantage in terms of saving computer memory space and in terms of reducing computation time. The algorithm could also be modified to analyze each harmonic separately instead of all at the same time.

  4. 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)

  5. 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.

  6. Harmonization of Biodiesel Specifications

    SciTech Connect

    Alleman, T. L.

    2008-02-01

    Worldwide biodiesel production has grown dramatically over the last several years. Biodiesel standards vary across countries and regions, and there is a call for harmonization. For harmonization to become a reality, standards have to be adapted to cover all feedstocks. Additionally, all feedstocks cannot meet all specifications, so harmonization will require standards to either tighten or relax. For harmonization to succeed, the biodiesel market must be expanded with the alignment of test methods and specification limits, not contracted.

  7. 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.

  8. 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 9.23?m to 10.75?m 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%.

  9. 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.

  10. Passively Q-switched Nd:YAG/Cr(4+):YAG bonded crystal microchip laser operating at 1112??nm and its application for second-harmonic generation.

    PubMed

    Fu, S G; Ouyang, X Y; Liu, X J

    2015-10-10

    A passively Q-switched Nd:YAG/Cr4+:YAG microchip laser operating at 1112nm is demonstrated. Under a pump power of 5.5W, a maximum average output power of 623mW was obtained with T=6% output coupler, corresponding to an optical-to-optical conversion efficiency of 11.3% and a slope efficiency of 19.5%. The minimum pulse width was 2.8ns, the pulse energy and peak power were 39.3?J and 14kW, respectively. Additionally, based on the 1112nm laser, a 230mW 556nm green-yellow laser was achieved within an LBO crystal. PMID:26479822

  11. 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.

  12. Coherent combining of SHG converters through active phase control of the fundamental waves

    NASA Astrophysics Data System (ADS)

    Durcu, A.; Aubert, C.; Canat, G.; Le Gout, J.; Lombard, L.; Bourdon, P.

    2014-03-01

    Coherent beam combining (CBC) by active phase control has proven to be an efficient and scalable way to increase the output power delivered by fiber laser systems. This study investigates the potential of this technique when applied to another type of laser sources: nonlinear optical frequency converters. Given that the efficiency of nonlinear conversion processes, here Second Harmonic Generation (SHG), relies on a phase-matching condition between the fundamental and the harmonic waves, an indirect control of the phase of an SHG beam through the fundamental wave is theoretically possible. This paper experimentally demonstrates such indirect phase control and its application to CBC of frequency converters. Two continuous-wave 1.55-?m fiber amplifiers are frequency doubled in PPLN crystals to generate 775-nm beams. These SH beams are coherently combined using frequency-tagging active phase control. A standard fibered electro-optic modulator (EOM) is used to control the phase of one of the 1.55-?m fiber amplifiers. This EOM provides both phase modulation for frequency-tagging and proper phase shifts to compensate for the phase fluctuations of the other 1.55-?m amplifier. Efficient coherent combining of these two 775-nm beams is successfully achieved: a ?/19.5 residual phase error is measured.

  13. Third-harmonic-upconversion enhancement from a single semiconductor nanoparticle coupled to a plasmonic antenna

    NASA Astrophysics Data System (ADS)

    Aouani, Heykel; Rahmani, Mohsen; Navarro-Cía, Miguel; Maier, Stefan A.

    2014-04-01

    The ability to convert low-energy quanta into a quantum of higher energy is of great interest for a variety of applications, including bioimaging, drug delivery and photovoltaics. Although high conversion efficiencies can be achieved using macroscopic nonlinear crystals, upconverting light at the nanometre scale remains challenging because the subwavelength scale of materials prevents the exploitation of phase-matching processes. Light-plasmon interactions that occur in nanostructured noble metals have offered alternative opportunities for nonlinear upconversion of infrared light, but conversion efficiency rates remain extremely low due to the weak penetration of the exciting fields into the metal. Here, we show that third-harmonic generation from an individual semiconductor indium tin oxide nanoparticle is significantly enhanced when coupled within a plasmonic gold dimer. The plasmonic dimer acts as a receiving optical antenna, confining the incident far-field radiation into a near field localized at its gap; the indium tin oxide nanoparticle located at the plasmonic dimer gap acts as a localized nonlinear transmitter upconverting three incident photons at frequency ω into a photon at frequency 3ω. This hybrid nanodevice provides third-harmonic-generation enhancements of up to 106-fold compared with an isolated indium tin oxide nanoparticle, with an effective third-order susceptibility up to 3.5 × 103 nm V-2 and conversion efficiency of 0.0007%. We also show that the upconverted third-harmonic emission can be exploited to probe the near-field intensity at the plasmonic dimer gap.

  14. 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.

  15. 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.

  16. Linking high harmonics from gases and solids

    NASA Astrophysics Data System (ADS)

    Vampa, G.; Hammond, T. J.; Thiré, N.; Schmidt, B. E.; Légaré, F.; McDonald, C. R.; Brabec, T.; Corkum, P. B.

    2015-06-01

    When intense light interacts with an atomic gas, recollision between an ionizing electron and its parent ion creates high-order harmonics of the fundamental laser frequency. This sub-cycle effect generates coherent soft X-rays and attosecond pulses, and provides a means to image molecular orbitals. Recently, high harmonics have been generated from bulk crystals, but what mechanism dominates the emission remains uncertain. To resolve this issue, we adapt measurement methods from gas-phase research to solid zinc oxide driven by mid-infrared laser fields of 0.25 volts per ångström. We find that when we alter the generation process with a second-harmonic beam, the modified harmonic spectrum bears the signature of a generalized recollision between an electron and its associated hole. In addition, we find that solid-state high harmonics are perturbed by fields so weak that they are present in conventional electronic circuits, thus opening a route to integrate electronics with attosecond and high-harmonic technology. Future experiments will permit the band structure of a solid to be tomographically reconstructed.

  17. Linking high harmonics from gases and solids.

    PubMed

    Vampa, G; Hammond, T J; Thir, N; Schmidt, B E; Lgar, F; McDonald, C R; Brabec, T; Corkum, P B

    2015-06-25

    When intense light interacts with an atomic gas, recollision between an ionizing electron and its parent ion creates high-order harmonics of the fundamental laser frequency. This sub-cycle effect generates coherent soft X-rays and attosecond pulses, and provides a means to image molecular orbitals. Recently, high harmonics have been generated from bulk crystals, but what mechanism dominates the emission remains uncertain. To resolve this issue, we adapt measurement methods from gas-phase research to solid zinc oxide driven by mid-infrared laser fields of 0.25 volts per ngstrm. We find that when we alter the generation process with a second-harmonic beam, the modified harmonic spectrum bears the signature of a generalized recollision between an electron and its associated hole. In addition, we find that solid-state high harmonics are perturbed by fields so weak that they are present in conventional electronic circuits, thus opening a route to integrate electronics with attosecond and high-harmonic technology. Future experiments will permit the band structure of a solid to be tomographically reconstructed. PMID:26108855

  18. 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.

  19. 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.

  20. Thermionic converters for ISUS

    NASA Astrophysics Data System (ADS)

    James, Edmund L.; Ramsey, William D.; Talbot, Gregory J.

    1997-01-01

    Eight alkali metal thermionic power converters were produced for a ground-based design verification test of a bimodal power and propulsion system. The effort provided a significant development step toward a spaceflight demonstration of the Integrated Solar Upper Stage (ISUS). The converters are electrically connected in series to produce a nominal eight (8) volt, 250 Watt output. In the power mode of the bimodal system, solar energy is concentrated to heat the converters to their operating range of 1900 K to 2200 K. The converter design, including thermal diode, heatpipe-radiator physical dimensions and weight are discussed, as are fabrication and prototype development. Test results are presented for individual converters and the 8-converter array, including current voltage characteristics, power density and power-to-weight ratio. Tests of series arrays of 16 and 32 converters are planned as part of this development.

  1. 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.

  2. Converter-based solution to power quality problems on radial distribution lines

    SciTech Connect

    Zyl, A. van; Enslin, J.H.R.; Spee, R.

    1996-11-01

    In this paper it is shown that the converter-based Power Quality Manager is a viable solution to power quality problems on radial lines. It is capable of harmonic isolation, improving voltage regulation and flicker compensation simultaneously. These functions can also be implemented independently. The Power Quality Manager is a hybrid device comprising passive components and a converter. The converter power rating is lower than that required by an equivalent active filter or converter-based Static Var Compensator.

  3. A `beam cleaner' for harmonic selection/rejection

    NASA Astrophysics Data System (ADS)

    Karanfil, C.; Chapman, L. D.; Bunker, G. B.; Segre, C. U.; Leyarovska, N. E.

    2000-06-01

    A `beam cleaner' for selection of a harmonic from the beamline monochromator and rejection of other harmonics has been developed using a bent Laue crystal post-monochromator. This is a set of cylindrically bent Si (111) crystals that are aligned to diffract the 2nd harmonic (3× fundamental) from the beamline Si (111) monochromator. This device will reject the fundamental and other harmonics up to the Si (999) reflection from the monochromator. It has particular advantages over a flat crystal device since the reflectivity width is approximately 0.2 milliradian. This makes it insensitive to vibration and alignment errors. Over a narrow energy range it does not require adjustment. The diffraction efficiency of each crystal at 25 keV is ˜80% with an overall efficiency of the crystal pair ˜60%. The device is intended to be used for EXAFS at higher x-ray energies using the beamline monochromator harmonic. An additional benefit is that the crystal set can be passively adjusted to nearly eliminate (to the micron level) the vertical beam motion of a channel-cut mode beamline monochromator. Measurements and plans are presented.

  4. Interleaved power converter

    DOEpatents

    Zhu, Lizhi (Canton, MI)

    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.

  5. 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.

  6. 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.

  7. Selection rules for harmonic generation in solids

    NASA Astrophysics Data System (ADS)

    Moiseyev, Nimrod

    2015-05-01

    High-order harmonic generation (HHG) in a bulk crystal was first observed in 2011 [S. Ghimire, A. D. DiChiara, E. Sistrunk, P. Agostini, L. F. DiMauro, and D. A. Reis, Nat. Phys. 7, 138 (2011), 10.1038/nphys1847]. Only odd-order harmonics were observed as expected on the basis of the selection rules in solids, which were derived when only the interband currents were taken into consideration. Here we study HHG in solids when the intraband currents are taken into consideration as well. We show that the dynamical selection rules are broken in solids and the possibility of generation of even-order harmonics cannot be excluded on the basis of the dynamical symmetry analysis. However, a simple analysis of the expression we obtained for the amplitude of the emitted high-order harmonics shows, without the need to carry out numerical calculations, that the even-order harmonics are suppressed due to the localization of the field-free one-electron density probability on the atoms in the solids.

  8. Prediction of core saturation instability at an HVDC converter

    SciTech Connect

    Burton, R.S.; Fuchshuber, C.F.; Woodford, D.A.; Gole, A.M.

    1996-10-01

    Core saturation instability has occurred on several HVDC schemes resulting from interactions between second harmonic and dc quantities (voltages and currents) on the ac side of the converter and fundamental frequency quantities on the dc side of the converter. The instability can be reinforced by unbalanced saturation of the converter transformers. The paper presents an analytical method which can be used to quickly screen ac and dc system operating conditions to predict where core saturation instability is likely to occur. Analytical results have been confirmed using the digital transients simulation program PSCAD/EMTDC.

  9. Efficient and adaptive power-system harmonics control

    SciTech Connect

    Amin, A.M.A.

    1986-01-01

    Power-system harmonics have been known to exist on the power system for a long time. Today, with the introduction of new nonlinear loads, it is clar that power harmonics are becoming a serious and a challenging problem with the potential for damaging effects to both the consumer loads and the power system network. The first chapter in this dissertation examines the major sources of power system harmonics. This chapter also examines some of the available methods to reduce power system harmonics. The second chapter introduces a new adaptive harmonic cancellation approach. The analysis of the proposed approach is presented along with SPICE model results for this approach as applied to cancel one of the harmonics generated from a six-pulse, phase-controlled converter. The validity of this approach with regard to changes in different system parameters is studied. The third chapter introduces new efficient approaches for harmonic reduction. Beside the main goal of harmonic reduction, these approaches minimize expensive electric energy losses. The results of SPICE models establishes the usefulness of these approaches.

  10. Multidimensional high harmonic spectroscopy

    NASA Astrophysics Data System (ADS)

    Bruner, Barry D.; Soifer, Hadas; Shafir, Dror; Serbinenko, Valeria; Smirnova, Olga; Dudovich, Nirit

    2015-09-01

    High harmonic generation (HHG) has opened up a new frontier in ultrafast science where attosecond time resolution and Angstrom spatial resolution are accessible in a single measurement. However, reconstructing the dynamics under study is limited by the multiple degrees of freedom involved in strong field interactions. In this paper we describe a new class of measurement schemes for resolving attosecond dynamics, integrating perturbative nonlinear optics with strong-field physics. These approaches serve as a basis for multidimensional high harmonic spectroscopy. Specifically, we show that multidimensional high harmonic spectroscopy can measure tunnel ionization dynamics with high precision, and resolves the interference between multiple ionization channels. In addition, we show how multidimensional HHG can function as a type of lock-in amplifier measurement. Similar to multi-dimensional approaches in nonlinear optical spectroscopy that have resolved correlated femtosecond dynamics, multi-dimensional high harmonic spectroscopy reveals the underlying complex dynamics behind attosecond scale phenomena.

  11. Basic technology of fast growing normal and partially deuterated KDP crystals

    SciTech Connect

    Fujioka, K.; Matsuo, S.; Kanabe, T.; Nakatsuka, M.; Nakai, S.

    1995-12-31

    The recent key issue of the efficient implosion in an inertial confinement fusion experiments is the improvement of the irradiation uniformity where the partially coherent light and the phase plate were used. The partially coherent light has wide spectral width and large beam divergence. The partially deuterated KDP crystal is suitable as the effective harmonic converter. The distribution coefficient of deuterium in the crystal depends on that of the growth solution. It was not affected, even if the saturated temperature and the supersaturation of the growth solution were changed. 13%-deuterated KDP crystal of 9 x 9 x 11 cm size was grown in which the deuterated rate was constant within the measurement error of {+-} 1 %. The excess energy due to an over heading and/or an acoustic energy to the solution and the pH control realized higher level of supersaturation. KDP crystal were grown up to 50mm/day.

  12. Fractional Simple Harmonic Oscillator

    NASA Astrophysics Data System (ADS)

    Narahari Achar, B. N.; Hanneken, John W.; Clarke, Ted J.; Skaggs, Jeremy M.

    2000-03-01

    Applications of fractional calculus to physics have received considerable attention recently, including generalization of the simple harmonic oscillator problem. This paper presents a survey of several approaches that have been proposed and discusses the advantages and disadvantages thereof. An approach to be preferred is based on the generalization of the integral equation of the simple harmonic oscillator that involves physically meaningful initial conditions. A complete formal solution to the equation of motion together with graphical display will be presented.

  13. 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.

  14. Analysis of dc harmonics using the three-pulse model for the intermountain power project HVDC transmission

    SciTech Connect

    Dickmander, D.L.; Peterson, K.J.

    1989-04-01

    The harmonic analysis of the dc-side of an HVDC line transmission requires realistic models of the converters, the dc line, and other relevant equipment. These models must include all important paths for harmonic current, and appropriate sources of harmonic voltage generation. The classical converter modeling technique has been demonstrated to be insufficient in field measurements and analysis of the harmonic spectra found on recent HVDC line transmission. For this reason, a new model of the converter bridge which takes into account the major stray capacitances in the converter (the three-pulse model) has been developed, and is described in detail elsewhere. This paper presents comparisons between the classical and three-pulse calculations for the Intermountain Power Project (IPP) HVDC transmission. The calculation results from the three-pulse model agree favorably with the harmonics found in field measurements.

  15. Frequency doubling crystals

    SciTech Connect

    Wang, F.; Velsko, S.P.

    1989-10-24

    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.

  16. 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.

  17. A New Harmonic Mitigation Scheme for MMC - An Experimental Approach

    NASA Astrophysics Data System (ADS)

    Madichetty, S.; Dasgupta, A.; Jinka, S.

    2014-06-01

    A multilevel converter has been brought into limelight in this article, however, particular attention has been provided to the form and function of modular multilevel converter (MMC) with new design, control and harmonic mitigation schemes. A new controller scheme has been proposed to mitigate the lower and higher order harmonics. The proposed scheme shows its effectiveness by theoretical calculations, verified by simulation and experimental results. Till date, research in this field is very limited with circulating currents and harmonics as the major problem. This article effectively addresses the problem with prototype 1 kVA implementation and attempts to make a detailed analysis with their functions in comprehensive manner with high-voltage DC application under different conditions. Also, the applicability of zero voltage switching at turn ON and zero current transition at turn OFF has been verified experimentally. The strategic conclusions on MMC have been made in order to make the system more robust in operation, less complexity in design and control.

  18. Spatial and energy parameters of laser radiation and second harmonic upon self-frequency doubling

    SciTech Connect

    Laptev, G D; Novikov, Aleksei A; Chirkin, Anatolii S

    2005-01-31

    The intracavity second-harmonic generation of laser radiation in an active nonlinear crystal is studied. The spatial distributions of the intensity and power of laser radiation and its second harmonic are calculated by the method of numerical simulations as functions of the parameters of the resonator, active nonlinear crystal, and pump. The analysis is performed for a periodically poled Nd:Mg:LiNbO{sub 3} crystal taking diffraction into account. (active media. lasers)

  19. Carrier frequency noise from HVDC converters

    NASA Astrophysics Data System (ADS)

    Fisher, F. A.; Griess, L. D.; Laforest, J. J.; Lindh, C. B.

    1982-08-01

    The development of an ac and dc side carrier frequency noise model for incorporation in the Bonneville Power Administration's ElectroMagnetic Transient Program (EMTP) is described. This model of an HVDC Station generates the characteristic wave shapes of voltages and currents in the time plane on which a Fast Fourier Transformer (FFT) is applied. The model representation of HVDC equipment such as converter transformers, smoothing reactors and harmonic filters is compared with de-energized impedance measurements of similar equipment in an HVDC Station. The carrier frequency range for the model covered is 10 kHz - 300 kHz. The measurements were obtained on the valve side and line side of the converter for both ac and dc sides. The calculated and measured noise were compared. The different measuring methods are described. A preferred measurement program is suggested and guidelines are indicated for power line carrier (plc) signal to noise ratios.

  20. 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.

  1. Harmonic conversion of phase-aberrated beam in CLBO

    NASA Astrophysics Data System (ADS)

    Gao, Yanxia; Fan, Dianyuan

    1998-08-01

    In this paper, based on the point of the statistical-optics, we have developed a discussion for the Type II second harmonic generation of short pulse laser beams with phase modulations fluctuations in the new crystal such as CLBO. In it, fundamental wave is aberrated beam of which the aberration is assumed to be a Gaussian random variable. The theory on focusing the both characteristics approximate and calculated results of fundamental wave and second harmonic VS phase aberration coefficient have been presented. It is applicable in designs of harmonic generation for high power lasers.

  2. Microminiature thermionic converters

    DOEpatents

    King, Donald B. (Albuquerque, NM); Sadwick, Laurence P. (Salt Lake City, UT); Wernsman, Bernard R. (Clairton, PA)

    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.

  3. Converting Nonclassicality into Entanglement

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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 S U (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.

  4. 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

  5. Tracking harmonic notch filter

    NASA Astrophysics Data System (ADS)

    Emo, Frederick L.

    1990-07-01

    Disclosed in this patent is an electronic filter for automatically tracking and removing harmonically related interfering electrical signals such as power line interference harmonics without attenuating other signals of interest even though the signals are frequency stable and/or near the interference signal frequencies. The filter comprises a very narrow band electronic commutated capacitor-bank comb-notch filter driven by a counter/decoder circuit which is in turn driven by a phase locked loop. The filter also comprises two narrow band analog filters tuned to the two lowest harmonics of the interfering signal and drives the comb-notch at unit multiples of the fundamental of the interference frequency. This action is continuous such that center frequencies of the notches are automatically adjusted to compensate for small variations in the interference frequency.

  6. 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.

  7. 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

  8. Multitone harmonic radar

    NASA Astrophysics Data System (ADS)

    Mazzaro, Gregory J.; Martone, Anthony F.

    2013-05-01

    Nonlinear radar exploits the electronic response from a target whose reflected frequencies are different from those transmitted. Reception of frequencies that are not part of the transmitted probe distinguishes the received signal from a linear return produced by clutter and indicates the presence of electronics. Presented in this paper is a type of nonlinear radar that transmits multiple frequencies and listens for a harmonic of these frequencies as well as other frequencies near that harmonic. A laboratory test-bed has been constructed to demonstrate the multitone radar concept. Measurements of nonlinear responses from RF devices probed by multiple tones are reported.

  9. 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.

  10. Frequency conversion in compositionally graded PPLN crystals

    SciTech Connect

    Galutskiy, V V; Stroganova, E V; Shmargilov, S A; Yakovenko, N A

    2014-01-31

    This paper considers the effect of the longitudinal lithium concentration distribution in PPLN converters on their efficiency in high-power cw laser second harmonic generation. (nonlinear optical phenomena)

  11. 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 the angular performance requirements, a precision monolithic cell with full edge support for mounting the optics to 10 {micro}rad angular and 1-5 {micro}m flatness tolerances is required The NIF frequency converter design is a major step in improving both conversion efficiency and precision of the mount design Another major consideration in the FOC design is the trade-off between cost of manufacturing the cell and the performance of the mount An interesting balance of what can be accomplished with a conventional machine tool in a commercial shop to produce prototype FOC` s will be discussed Metrology issues involved in qualifying the FOC are also discussed.

  12. AC/DC converter

    NASA Astrophysics Data System (ADS)

    Jain, Praveen K.

    1992-08-01

    In a system such as a 20 kHz space station primary electrical power distribution system, power conversion from AC to DC is required. Some of the basic requirements for this conversion are high efficiency, light weight and small volume, regulated output voltage, close to unity input power factor, distortionless input current, soft-starting, low electromagnetic interference, and high reliability. An AC-to-DC converter is disclosed which satisfies the main design objectives of such converters for use in space. The converter of the invention comprises an input transformer, a resonant network, a current controller, a diode rectifier, and an output filter. The input transformer is for connection to a single phase, high frequency, sinusoidal waveform AC voltage source and provides a matching voltage isolating from the AC source. The resonant network converts this voltage to a sinusoidal, high frequency bidirectional current output, which is received by the current controller to provide the desired output current. The diode rectifier is connected in parallel with the current controller to convert the bidirectional current into a unidirectional current output. The output filter is connected to the rectifier to provide an essentially ripple-free, substantially constant voltage DC output.

  13. Hybrid-active filtering of harmonic currents in power systems

    SciTech Connect

    Rastogi, M.; Mohan, N.; Edris, A.A.

    1995-10-01

    Use of nonlinear loads and devices in power systems is expected to grow rapidly. Examples are thyristor-controlled inductors for FACTS, converters for HVDC transmission and large adjustable speed drives. All of these loads inject harmonic currents into the power system. A novel hybrid filter topology and its control, to prevent such harmonic currents from entering the power system, are presented in this paper. Analysis shows that in the proposed filter, the power electronic converter, required to generate harmonic currents for compensation, has a rating of only 9% when compared to the converter rating in an active filter and approximately one-half of that in a series-hybrid filter discussed in the literature. The proposed topology enables practical implementation of active harmonic current filters. The control of this filter under transient conditions such as start-up and during steady state is demonstrated by means of simulations. Results from a scaled-down hardware prototype are presented to verify the simulations.

  14. Experimental Harmonic Motion

    NASA Astrophysics Data System (ADS)

    Searle, G. F. C.

    2014-05-01

    1. Elementary theory of harmonic motion; 2. Experimental work in harmonic motion; Experiment 1. Determination of g by a simple pendulum; Experiment 2. Harmonic motion of a body suspended by a spring; Experiment 3. Harmonic motion of a rigid body suspended by a torsion wire; Experiment 4. Study of a system with variable moment of inertia; Experiment 5. Dynamical determination of ratio of couple to twist for a torsion wire; Experiment 6. Comparison of the moments of inertia of two bodies; Experiment 7. Experiment with a pair of inertia bars; Experiment 8. Determination of the moment of inertia of a rigid pendulum; Experiment 9. Experiment on a pendulum with variable moment of inertia; Experiment 10. Determination of g by a rigid pendulum; Experiment 11. Pendulum on a yielding support; Experiment 12. Determination of the radius of curvature of a concave mirror by the oscillations of a sphere rolling in it; Experiment 13. Determination of g by the oscillations of a rod rolling on a cylinder; Experiment 14. Study of a vibrating system with two degrees of freedom; Note 1. On the vibration of a body suspended from a light spring; Note 2. Periodic time of a pendulum vibrating through a finite arc; Note 3. Periodic time for finite motion; Note 4. Periodic times of a pendulum with two degrees of freedom.

  15. 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.)

  16. 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

  17. 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.

  18. 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.

  19. Vector generator scan converter

    DOEpatents

    Moore, James M. (Livermore, CA); Leighton, James F. (Livermore, CA)

    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.

  20. 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.

  1. 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.

  2. Advanced Control Strategy for Single-Phase Voltage-Source Active Rectifier with Low Harmonic Emission

    NASA Astrophysics Data System (ADS)

    Blahnk, Vojt?ch; Peroutka, Zden?k; Talla, Jakub

    2014-03-01

    This paper introduces the advanced control of single-phase voltage-source active rectifier. This control provide direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. Our proposed control strategy combines PR controller with feed-forward model and low-frequency harmonic compensator based on resonant controllers. Achieved experimental results show excellent converter behavior, where converter is fed by strongly distorted supply voltage.

  3. Harmonic analysis of multi-phase electric-power distribution systems

    SciTech Connect

    Hosseini, S.H.

    1988-01-01

    This study presents a computer program as a tool for the harmonic analysis of multi-phase electric power distribution systems. In the program, the source of harmonics can be any number of multi-phase harmonic currents and/or voltages, or up to 10 three-phase converts. Frequency-dependent models of ac network elements are assembled into a sparse admittance matrix. Then, sparsity techniques are employed to determine the current flow in all elements and voltages at all busses throughout the system at any harmonic frequency up to 3 KHz. Voltage distortion factors that represent the overall effects of the harmonics of the system voltages are also calculated. The digital program was then applied to a multi-phase distribution system in order to observe the response of the system to the various changes that were made in the system. It was found that the converter size and location, the capacitor bank sizes and locations, and the representation of the system loads are factors in determining in harmonic current flows and the level of voltage-distortion factors. Also, the response of the system to single-phase harmonic sources was investigated, and it was discovered that the effects of single-phase harmonic sources can be serious enough that they should not be ignored in the harmonic analysis of multi-phase systems.

  4. 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

  5. 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.

  6. Second harmonic inversion for ultrasound contrast harmonic imaging.

    PubMed

    Pasovic, Mirza; Danilouchkine, Mike; Faez, Telli; van Neer, Paul L M J; Cachard, Christian; van der Steen, Antonius F W; Basset, Olivier; de Jong, Nico

    2011-06-01

    Ultrasound contrast agents (UCAs) are small micro-bubbles that behave nonlinearly when exposed to an ultrasound wave. This nonlinear behavior can be observed through the generated higher harmonics in a back-scattered echo. In past years several techniques have been proposed to detect or image harmonics produced by UCAs. In these proposed works, the harmonics generated in the medium during the propagation of the ultrasound wave played an important role, since these harmonics compete with the harmonics generated by the micro-bubbles. We present a method for the reduction of the second harmonic generated during nonlinear-propagation-dubbed second harmonic inversion (SHI). A general expression for the suppression signals is also derived. The SHI technique uses two pulses, p' and p?, of the same frequency f(0) and the same amplitude P(0) to cancel out the second harmonic generated by nonlinearities of the medium. Simulations show that the second harmonic is reduced by 40?dB on a large axial range. Experimental SHI B-mode images, from a tissue-mimicking phantom and UCAs, show an improvement in the agent-to-tissue ratio (ATR) of 20?dB compared to standard second harmonic imaging and 13?dB of improvement in harmonic power Doppler. PMID:21540492

  7. RF to digital converter

    NASA Technical Reports Server (NTRS)

    Flanders, T. E.; Kosa, G.

    1973-01-01

    Converter can be used for automatic spectrum analysis. Automatic gain amplifier digitizes RF amplitude, and amplifier gain is measured by binary counter. Amount of gain corresponds to signal level and is proportional to count in counter. System can be used to calculate AM and FM modulation index and other parameters of pulse-modulated FM waves.

  8. 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. PMID:19164018

  9. General Theory of Harmonics Generation thru Energy Transformation

    NASA Astrophysics Data System (ADS)

    Czyzyk, Don

    2013-04-01

    Energy, whatever its form, can be converted into an electrical signal. When analyzed is found to be comprised of a continuum of sinusoidal frequencies called a harmonic spectrum H/S. This paper addresses the question of how/why, in general, are these sinusoidal frequencies (harmonics) generated and in particular how they are produced in electronic circuits. To address this question many varied experiments were performed. Some experiments used just batteries while others used mechanical, acoustic, pneumatic, thermal, magnetic, hydraulic or photonic devices. All these devices were used to investigate the nature of harmonic generation from the perspective of the en masse movement of conduction electrons. Primarily performing electronic experiments on the envelope of a single pulse revealed that a pulse of one wavelength can be separated into basic individual segments. The energy of each individual segment, when absorbed by conduction electrons, is transformed into a unique H/S. Recombining all the individual segments that comprise a pulse envelope, involves the constructive or destructive interactions of their harmonic spectrums leading to the amplitudes of some harmonics being increased and others reduced or eliminated. The result is a pulse envelope with a different harmonic series.

  10. B1 magnet harmonics

    SciTech Connect

    Barnes, P D

    2000-05-30

    During the B0 Overpass construction for the CDF detector at Fermilab, 33 B1 magnets were measured using a bucked tangential coil. Measurements were made on the midplane, at the centerline and at {+-} 1 inch horizontal displacement. Since the coil was only 62 inches long, measurements were made at four longitudinal positions. Because of the design of the Main Ring, it was sufficient to combine data from all positions and report the harmonic spectrum for the magnet as a whole. For modeling the Scrounge-atron, it is more useful to treat each measurement position separately. The author reports here an analysis of the harmonic spectra at each probe position, based on the original data.

  11. Liquid metal thermal electric converter

    DOEpatents

    Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

    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.

  12. Liquid metal thermal electric converter

    SciTech Connect

    Abbin, J.P.; Andrake, C.E.; Lukens, L.L.; Moreno, J.B.

    1989-09-19

    This patent describes 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.

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

    SciTech Connect

    Schmitt, M.J.; McVey, B.D.

    1990-01-01

    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 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. 11 refs., 9 figs.

  14. 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.

  15. Second Harmonic Generation in WSe2

    NASA Astrophysics Data System (ADS)

    Ribeiro-Soares, J.; Janisch, C.; Liu, Z.; Elas, A. L.; Dresselhaus, M. S.; Terrones, M.; Canado, L. G.; Jorio, A.

    2015-12-01

    Second harmonic generation of single- and few-layer mechanically exfoliated tungsten diselenide (WSe2) samples are studied. The value of the effective second-order nonlinear susceptibility for monolayer WSe2 is obtained, being three orders of magnitude larger than the values usually reported for other nonlinear bulk crystals. The presence of a monolayer is certified by symmetry analysis of the Raman modes and the occurrence of a direct band gap. Our results on WSe2 solidify the family of transition metal dichalcogenides as two-dimensional systems with ultra high second-order nonlinear susceptibility.

  16. Thermionic energy converters

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (inventor)

    1983-01-01

    The efficiency of thermionic energy converters is improved by internal distribution of tiny sorted cesium diodes driven by the thermal gradient between the primary emitter and the collector. The tiny, sorted diode distribution comprises protrusions of the emitter material from the main emitter face which contact the main collector face thermally but not electrically. The main collector ends of the protrusions are separated from the main collector by a thin layer of insulation, such as aluminum oxide. The shorted tiny diode distribution augments cesium ionization through internal thermal effects only within the main diode. No electrical inputs are required. This ionization enhancement by the distribution of the tiny shorted diodes not only reduces the plasma voltage drop but also increases the power output and efficiency of the overall thermionic energy converter.

  17. 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.

  18. Enhanced second harmonic generation from coupled asymmetric plasmonic metal nanostructures

    NASA Astrophysics Data System (ADS)

    Yildiz, Bilge Can; Emre Tasgin, Mehmet; Kurtulus Abak, Musa; Coskun, Sahin; Emrah Unalan, Husnu; Bek, Alpan

    2015-12-01

    We experimentally demonstrate that two coupled metal nanostructures (MNSs), a silver nanowire and bipyramid, can produce ?30 times enhanced second harmonic generation compared to the particles alone. We develop a simple theoretical model, presenting the path interference effects in the nonlinear response of coupled MNSs. We show that the reason for such an enhancement can be the occurrence of a Fano resonance due to the coupling of the converter MNS to the long-lived mode of the attached MNS.

  19. Towards automated biomedical ontology harmonization.

    PubMed

    Uribe, Gustavo A; Lopez, Diego M; Blobel, Bernd

    2014-01-01

    The use of biomedical ontologies is increasing, especially in the context of health systems interoperability. Ontologies are key pieces to understand the semantics of information exchanged. However, given the diversity of biomedical ontologies, it is essential to develop tools that support harmonization processes amongst them. Several algorithms and tools are proposed by computer scientist for partially supporting ontology harmonization. However, these tools face several problems, especially in the biomedical domain where ontologies are large and complex. In the harmonization process, matching is a basic task. This paper explains the different ontology harmonization processes, analyzes existing matching tools, and proposes a prototype of an ontology harmonization service. The results demonstrate that there are many open issues in the field of biomedical ontology harmonization, such as: overcoming structural discrepancies between ontologies; the lack of semantic algorithms to automate the process; the low matching efficiency of existing algorithms; and the use of domain and top level ontologies in the matching process. PMID:24851964

  20. Why plasma harmonics?

    NASA Astrophysics Data System (ADS)

    Ganeev, R. A.

    2015-09-01

    We discuss the emergence of interest in the high-order harmonic generation (HHG) of ultrashort pulses propagated through laser-produced plasmas. It is shown that, during the last few years, substantial amendments of plasma HHG allowed in some cases the characteristics of gas HHG to be surpassed. The attractiveness of a new approach in coherent extreme ultraviolet radiation generation is demonstrated, which can also be used as a tool for laser-ablation-induced HHG spectroscopy of a giant class of solids. We present general ideas and prospects for this relatively new field of nonlinear optics.

  1. Next generation data harmonization

    NASA Astrophysics Data System (ADS)

    Armstrong, Chandler; Brown, Ryan M.; Chaves, Jillian; Czerniejewski, Adam; Del Vecchio, Justin; Perkins, Timothy K.; Rudnicki, Ron; Tauer, Greg

    2015-05-01

    Analysts are presented with a never ending stream of data sources. Often, subsets of data sources to solve problems are easily identified but the process to align data sets is time consuming. However, many semantic technologies do allow for fast harmonization of data to overcome these problems. These include ontologies that serve as alignment targets, visual tools and natural language processing that generate semantic graphs in terms of the ontologies, and analytics that leverage these graphs. This research reviews a developed prototype that employs all these approaches to perform analysis across disparate data sources documenting violent, extremist events.

  2. 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 exceed this initial performance estimates. In advancing the Technology Readiness Level (TRL) of this type of wave energy converter from 3 to 4, we find the CycWEC to exceed our initial estimates in terms of hydrodynamic performance. Once fully developed and optimized, it has the potential to not just outperform all other WEC technologies, but to also deliver power at a lower LCOE than competing conventional renewables like wind and solar. Given the large wave power resource both domestically and internationally, this technology has the potential to lead to a large improvement in our ability to produce clean electricity at affordable cost.

  3. Hydraulic torque converter

    SciTech Connect

    Becraft, G.R.

    1992-10-06

    This patent describes a torque converter having an impeller, a turbine and a stator forming a torus, wherein the torus has a median section having its radial dimension exceeding its axial dimension, and the torus having an axial dimension fixed at a predetermined axial offset, wherein at least one of the impeller and the turbine is configured as a flow path portion defined by a meanline design path having an outer radius and an inner radius, and wherein the outer radius is greater than the inner radius.

  4. Extremely high damage threshold of a new nonlinear crystal L-arginine phosphate and its deuterium compound

    SciTech Connect

    Yokotani, A.; Sasaki, T.; Yoshida, K.; Nakai, S. )

    1989-12-25

    L-arginine phosphate monohydrate (LAP) and deuterated LAP (DLAP) are new organic nonlinear optical materials useful for higher harmonics of radiation from high-power lasers. We measured the bulk laser damage threshold of these crystals using light from a 1.05 {mu}m laser with 1 and 25 ns pulse widths and 0.53 {mu}m laser light with 0.6 and 20 ns pulse widths. In every case, these crystals show much higher thresholds than potassium dihydrogen phosphate (KDP) and fused silica. These crystals are very interesting not only as a frequency converter but also as other optical components of high-power lasers, because of their extremely high damage threshold.

  5. Molecular germanium selenophosphate salts: phase-change properties and strong second harmonic generation.

    PubMed

    Morris, Collin D; Chung, In; Park, Sungoh; Harrison, Connor M; Clark, Daniel J; Jang, Joon I; Kanatzidis, Mercouri G

    2012-12-26

    A new series of germanium chalcophosphates with the formula A(4)GeP(4)Q(12) (A = K, Rb, Cs; Q = S, Se) have been synthesized. The selenium compounds are isostructural and crystallize in the polar orthorhombic space group Pca2(1). The sulfur analogues are isostructural to one another but crystallize in the centrosymmetric monoclinic space group C2/c. All structures contain the new molecular anion [GeP(4)Q(12)](4-); however, the difference between the sulfides and selenides arises from the change in crystal packing. Each discrete molecule is comprised of two ethane-like P(2)Q(6) units that chelate to a central tetrahedral Ge(4+) ion in a bidentate fashion. The selenides were synthesized pure by stoichiometric reaction of the starting materials, whereas the sulfides contained second phases. The band gaps of the molecular salts are independent of the alkali metal counterions and have a value of 2.0 eV for the selenides and 3.0-3.1 eV for the sulfides. All A(4)GeP(4)Se(12) compounds melt congruently, and the potassium analogue can be quenched to give a glassy phase that retains its short-range order as shown by Raman spectroscopy and powder X-ray diffraction. Interestingly, K(4)GeP(4)Se(12) is a phase-change material that reversibly converts between glassy and crystalline states and passes through a metastable crystalline state upon heating just before crystallizing into its slow-cooled form. Initial second harmonic generation (SHG) experiments showed crystalline K(4)GeP(4)Se(12) outperforms the other alkali metal analogues and exhibits the strongest second harmonic generation response among reported quaternary chalcophosphates, ~30 times that of AgGaSe(2) at 730 nm. A more thorough investigation of the nonlinear optical (NLO) properties was performed across a range of wavelengths that is almost triple that of previous reports (? = 1200-2700 nm) and highlights the importance of broadband measurements. Glassy K(4)GeP(4)Se(12) also exhibits a measurable SHG response with no poling. PMID:23157167

  6. Gallium phosphide energy converters

    SciTech Connect

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

    1995-10-01

    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 {minus}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.

  7. Gallium phosphide energy converters

    NASA Astrophysics Data System (ADS)

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

    1995-10-01

    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.

  8. 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.

  9. 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.

  10. 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.

  11. DC systems with transformerless converters

    SciTech Connect

    Vithayathil, J.J.; Mittlestadt, W.; Bjoerklund, P.E.

    1995-07-01

    A technical and economic feasibility study of HVDC systems without converter transformers is presented. The presentation includes proposed solutions to the drawback related to the absence of galvanic separation between the ac and dc systems, if the converter transformers are eliminated. The results show that HVDC systems without converter transformers are both technically and economically feasible. The cost savings can be substantial.

  12. Sound velocity anisotropy in cubic crystals

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Park, H. Y.

    1983-01-01

    Simple analytical expressions may be derived for sound velocities in cubic crystals by using lattice harmonics or functions which are invariant under the crystal symmetry operations. These expressions are in good agreement with the exact results for typical crystals such as metallic iron and potassium fluoride.

  13. Harmonic generation at high intensities

    SciTech Connect

    Schafer, K.J.; Krause, J.L.; Kulander, K.C.

    1993-06-01

    Atomic electrons subject to intense laser fields can absorb many photons, leading either to multiphoton ionization or the emission of a single, energetic photon which can be a high multiple of the laser frequency. The latter process, high-order harmonic generation, has been observed experimentally using a range of laser wavelengths and intensities over the past several years. Harmonic generation spectra have a generic form: a steep decline for the low order harmonics, followed by a plateau extending to high harmonic order, and finally an abrupt cutoff beyond which no harmonics are discernible. During the plateau the harmonic production is a very weak function of the process order. Harmonic generation is a promising source of coherent, tunable radiation in the XUV to soft X-ray range which could have a variety of scientific and possibly technological applications. Its conversion from an interesting multiphoton phenomenon to a useful laboratory radiation source requires a complete understanding of both its microscopic and macroscopic aspects. We present some recent results on the response of single atoms at intensities relevant to the short pulse experiments. The calculations employ time-dependent methods, which we briefly review in the next section. Following that we discuss the behavior of the harmonics as a function of laser intensity. Two features are notable: the slow scaling of the harmonic intensities with laser intensity, and the rapid variation in the phase of the individual harmonics with respect to harmonic order. We then give a simple empirical formula that predicts the extent of the plateau for a given ionization potential, wavelength and intensity.

  14. Analysis of second harmonic instability for the Chateauguay HVDC/SVC scheme

    SciTech Connect

    Hammad, A.E. )

    1992-01-01

    The Chateauguay HVDC back-to-back scheme with interconnections to the 765 kV transmission to U.S.A. and to Beauharnois generators can exhibit, under certain operating conditions, second harmonic resonance problems. This paper presents a thorough analysis of the problem using an eigenvalue and frequency domain approach. The analysis explains the mechanism of exciting the second harmonic instability by the presence of HVDC converters. The influence of changing the control parameters of the static VAR compensatory at the Chateauguay terminal is also studied. Finally, an assessment is made for the effectiveness of present countermeasure schemes, namely; the auxiliary dc stabilizing controls and the installation of second harmonic filters.

  15. 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.

  16. Nonlinear optical effects in liquid crystals

    NASA Astrophysics Data System (ADS)

    Wong, G. K.

    1980-12-01

    A d.c. field induced optical second-harmonic generation in nematic and cholesteric liquid crystals is investigated. In addition, flexo-electric induces second-harmonic generation in nematic MBBA is studied. The experiments involve the detection of optical radiation at second-harmonic frequency when aligned thin film liquid crystals samples are irradiated with laser beam at the fundamental frequency. The laser used in a Q-switched Nd-YAG laser. Sample alignment is achieved either with rubbing technique or by coating glass spacers with 100 A thick of Si2. Experiments on nematic liquid crystals show that the temperature dependence of nematic order parameters can be obtained from the measurement of d.c. induced second-harmonic generation. It is also demonstrated that flexoelectric effect can give rise to second-harmonic generation in nematic liquid crystal and the birefringence of nematic crystal can be used to achieve phase-matching. In the cholesteric liquid crystal, it is demonstrated that the lattice momentum associated with the one dimensional periodicity of cholesteric structure can be used to achieve phase-matching. Comparison of the measured temperature dependence of nematic order parameters with the predictions of the existing statistical theories of nematic ordering indicates that these theories are not quantitatively reliable. The phase-matchability of liquid crystals shows that these media may be useful as practical optical harmonic generators.

  17. 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.

  18. 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.

  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. 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?

  1. 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...

  2. Galilean covariant harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Horzela, Andrzej; Kapuscik, Edward

    1993-01-01

    A Galilean covariant approach to classical mechanics of a single particle is described. Within the proposed formalism, all non-covariant force laws defining acting forces which become to be defined covariantly by some differential equations are rejected. Such an approach leads out of the standard classical mechanics and gives an example of non-Newtonian mechanics. It is shown that the exactly solvable linear system of differential equations defining forces contains the Galilean covariant description of harmonic oscillator as its particular case. Additionally, it is demonstrated that in Galilean covariant classical mechanics the validity of the second Newton law of dynamics implies the Hooke law and vice versa. It is shown that the kinetic and total energies transform differently with respect to the Galilean transformations.

  3. 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.

  4. Frequency doubling crystals

    SciTech Connect

    Wang, F.; Velsko, S.P.

    1988-08-15

    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-acetyle hydroxyyproline. 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.

  5. Frequency doubling crystals

    SciTech Connect

    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.

  6. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    SciTech Connect

    Richman, B.A.; Bisson, S.E.; Trebino, R.

    1997-12-01

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle vs. wavelength to second order, we efficiently doubled tunable fundamental light near 660 nm over a range of 80 nm using a 4-mm-long type-I {beta}-Barium Borate (BBO) crystal. Another lossless set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 {mu}rad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10%.

  7. Pulsed thermionic converter study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasmadynamic accelerator (MPD arc jet) is described, and the results of preliminary analyses are presented. In this system, the MPD thruster operates intermittently at higher voltages and power levels than the thermionic generating unit. A typical thrust pulse from the MPD arc jet is characterized by power levels of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. The thermionic generating unit operates continuously but with a lower power level of approximately 0.4 MWe. Energy storage between thrust pulses is provided by building up a large current in an inductor using the output of the thermionic converter array. Periodically, the charging current is interrupted, and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. The results of the preliminary analysis show that a coupling effectiveness of approximately 85 to 90% is feasible for a nominal 400 KWe system with an inductive unit suitable for a flight vehicle.

  8. Digital regulation of a phase controlled power converter

    SciTech Connect

    Schultheiss, C.; Haque, T.

    1995-12-01

    The Relativistic Heavy Ion Collider, now in construction at Brookhaven National Laboratory, will use phase controlled power converters for the main dipole and quadrupole magnet strings. The rectifiers in these power supplies will be controlled by a digital regulator based on the TI 320C30 Digital Signal Processor (DSP). The DSP implements the current loop, the voltage loop, and a system to actively reduce the sub-harmonic ripple components. Digital firing circuits consisting of a phase locked lop and counters are used to fire the SCRs. Corrections for the sub-harmonic reduction are calculated by the DSP and stored in registers in the firing circuit. These corrections are added in hardware, to the over-all firing count provided by the DSP. the resultant count is compared to a reference counter to fire the SCRs. This combination of a digital control system and the digital firing circuits allows the correction of the sub-harmonics in a real-time sense. A prototype of the regulator has been constructed, and the preliminary testing indicates a sub-harmonic reduction of 60 dB.

  9. 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.

  10. Harmonic Measure of Critical Curves

    SciTech Connect

    Bettelheim, E.; Rushkin, I.; Gruzberg, I.A.; Wiegmann, P.

    2005-10-21

    Fractal geometry of critical curves appearing in 2D critical systems is characterized by their harmonic measure. For systems described by conformal field theories with central charge c{<=}1, scaling exponents of the harmonic measure have been computed by Duplantier [Phys. Rev. Lett. 84, 1363 (2000)] by relating the problem to boundary two-dimensional gravity. We present a simple argument connecting the harmonic measure of critical curves to operators obtained by fusion of primary fields and compute characteristics of the fractal geometry by means of regular methods of conformal field theory. The method is not limited to theories with c{<=}1.

  11. 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.

  12. Second harmonic generation from ZnO films and nanostructures

    NASA Astrophysics Data System (ADS)

    Larciprete, Maria Cristina; Centini, Marco

    2015-09-01

    Zinc oxide ZnO is a n-type semiconductor having a wide direct band gap (3.37 eV) as well as a non-centrosymmetric crystal structure resulting from hexagonal wurtzite phase. Its wide transparency range along with its second order nonlinear optical properties make it a promising material for efficient second harmonic generation processes and nonlinear optical applications in general. In this review, we present an extensive analysis of second harmonic generation from ZnO films and nanostructures. The literature survey on ZnO films will include some significant features affecting second harmonic generation efficiency, as crystalline structure, film thickness, surface contributes, and doping. In a different section, the most prominent challenges in harmonic generation from ZnO nanostructures are discussed, including ZnO nanowires, nanorods, and nanocrystals, to name a few. Similarly, the most relevant works regarding third harmonic generation from ZnO films and nanostructures are separately addressed. Finally, the conclusion part summarizes the current standing of published values for the nonlinear optical coefficients and for ZnO films and nanostructures, respectively.

  13. 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.

  14. Combinational tasks performed by second-harmonic-generated holograms.

    PubMed

    Andreoni, A; Bondani, M; Potenza, M A

    2000-11-01

    Second-harmonic-generated holograms directly provide the outputs of logical gates AND and NAND operating on optical bits encoded as amplitude modulations in the object and reference wave fronts. By use of a Nd:YAG laser and a beta-barium borate crystal, we realized a real-time half-adder of two one-digit binary numbers. The feasibility of highly parallel operation is also discussed. PMID:18066279

  15. Azimuthal anisotropy: The higher harmonics

    SciTech Connect

    Poskanzer, Arthur M.; STAR Collaboration

    2004-03-12

    We report the first observations of the fourth harmonic (v{sub 4}) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v{sub 4} is about a factor of 10 smaller than v{sub 2}. For the sixth (v{sub 6}) and eighth (v{sub 8}) harmonics upper limits on the magnitudes are reported.

  16. 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.

  17. 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.

  18. 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.

  19. A simple pulsed laser design for high harmonics generation

    NASA Astrophysics Data System (ADS)

    Bachmair, J.; Gmez Vzquez, R.; Bammer, F.

    2012-01-01

    We demonstrate a simple pulsed laser design with a potentially high efficiency for high harmonics generation. The basic idea is to generate pulsed laser operation with a resonantly oscillating piezo-electric crystal made of LiTaO3 or LiNbO3, i.e. Q-switching with a Single Crystal Photo-Elastic Modulators (SCPEM). The pulsed mode operation shows 30 (internal SHG) to 50 (external SHG) times higher green power than the cw-mode operation with a maximum green output of 290mW.

  20. 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.

  1. Theory and optical implementation of the geometrical approach of multiple circular harmonic filters

    NASA Astrophysics Data System (ADS)

    Shen, Lixin; Sheng, Yunlong; Prmont, Guy

    1995-07-01

    The circular harmonic filter contains only one component of the image. Its discrimination capability has been questionable. The geometrical approach of multiple circular harmonic filters uses relative locations of the correlation peaks as the rotation-, shift-, and intensity-invariant features for pattern recognition. Each feature depends on the entire image. This approach has a good discrimination capability. Optical real-time implementation of the on-axis continuous phase-only circular harmonic filters by the use of a commercial liquid-crystal television is shown. A harmonic analysis shows that the phase-mostly filter can tolerate coupled amplitude modulation at the acceptable expense of the output signal-to-noise ratio. An optical experiment of the geometrical approach of multiple circular harmonic filters for a multiple-image input is described. The cross-correlation peaks between the individual filters and the clutter are eliminated, because they are not in good locations.

  2. Performance testing of the Sandy Pond HVDC converter terminal

    SciTech Connect

    Donahue, J.A.; Fisher, D.A.; Railing, B.D.; Tatro, P.J. )

    1993-01-01

    Results of several performance tests for the 1,800 MW Sandy Pond HVDC converter terminal are presented and discussed. The work progressed during 1990 and 1991 and included tests for power line carrier interference, audible sound, ac and dc line faults and dc harmonic performance. The testing was conducted as part of the commissioning program for the first stage of the Quebec-New England Phase 2 multi-terminal system. In this stage, the Radisson (Quebec) and Sandy Pond (New England) terminals are operational.

  3. Optimal design of AC filter circuits in HVDC converter stations

    SciTech Connect

    Saied, M.M.; Khader, S.A.

    1995-12-31

    This paper investigates the reactive power as well as the harmonic conditions on both the valve and the AC-network sides of a HVDC converter station. The effect of the AC filter circuits is accurately modeled. The program is then augmented by adding an optimization routine. It can identify the optimal filter configuration, yielding the minimum current distortion factor at the AC network terminals for a prespecified fundamental reactive power to be provided by the filter. Several parameter studies were also conducted to illustrate the effect of accidental or intentional deletion of one of the filter branches.

  4. Relation of squeezed states between damped harmonic and simple harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Um, Chung-In; Yeon, Kyu-Hwang; George, Thomas F.; Pandey, Lakshmi N.

    1993-01-01

    The minimum uncertainty and other relations are evaluated in the framework of the coherent states of the damped harmonic oscillator. It is shown that the coherent states of the damped harmonic oscillator are the squeezed coherent states of the simple harmonic oscillator. The unitary operator is also constructed, and this connects coherent states with damped harmonic and simple harmonic oscillators.

  5. Analysis of harmonic spline gravity models for Venus and Mars

    NASA Technical Reports Server (NTRS)

    Bowin, Carl

    1986-01-01

    Methodology utilizing harmonic splines for determining the true gravity field from Line-Of-Sight (LOS) acceleration data from planetary spacecraft missions was tested. As is well known, the LOS data incorporate errors in the zero reference level that appear to be inherent in the processing procedure used to obtain the LOS vectors. The proposed method offers a solution to this problem. The harmonic spline program was converted from the VAX 11/780 to the Ridge 32C computer. The problem with the matrix inversion routine that improved inversion of the data matrices used in the Optimum Estimate program for global Earth studies was solved. The problem of obtaining a successful matrix inversion for a single rev supplemented by data for the two adjacent revs still remains.

  6. Laser third-harmonic generation in clustered plasmas

    NASA Astrophysics Data System (ADS)

    Tiwari, Pawan K.; Tripathi, V. K.

    2006-12-01

    An intense short pulse laser propagating through a gas jet comprised of clusters, quickly converts the clusters into plasma balls and causes oscillations of the electron cloud in the direction of the electric field of the laser. In each wave period, electrons spend a significant amount of their time outside the clusters, leaving behind a net positive charge and the clusters undergo Coulomb explosion and expand. During the expansion when the cluster electrons plasma frequency equals \\sqrt 3 times the laser frequency, \\omega _{{\\rm{pe}}} = \\sqrt 3 {\\kern 1pt} \\omega , the electron quiver velocity is resonantly enhanced. The nonlinear electron response gives rise to the generation of a third-harmonic. At a typical laser intensity of IL ap 1015 W cm-2 at 1 ?m wavelength, the normalized third-harmonic amplitude of the pump wave in a deuterium cluster of radius 100 , and density ~1014 cm-3, turns out to be 1.710-3.

  7. Harmonic Contribution Evaluation using Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Lian, Suo; Ito, Daisuke; Takayama, Satoshi; Ishigame, Atsushi; Kitagawa, Masahiro; Katayama, Kousaku; Nakatani, Hideyuki; Takeuchi, Masayasu

    The widespread use of power electronic devices caused the harmonic pollution in power systems. However, it is difficult to determine customer and utility responsibility for harmonic distortion at the point of common coupling (PCC). In this letter, we propose a method to evaluate harmonic contribution at the PCC using independent component analysis (ICA). This method can evaluate the true harmonic contribution of utility and customer without estimating the harmonic impedance.

  8. Efficiency Investigation of Electrical Generator-Converter Set

    NASA Astrophysics Data System (ADS)

    Leuchter, Jan; Bauer, Pavol

    The efficiency of the electrical GEN-SET (EGS) for speeds with diesel generator (?3000rpm) and feasibility of high-speed generator with gas turbine (?30000rpm) and permanent magnet synchronous generator is investigated. Three different configurations of power converter are considered. The paper given an answer to the question if a a full controlled rectifier should be employed or a version with diode rectifier is satisfactory? This is investigated also for high-speed generation. Different current forms for the three defined configurations with their harmonics and influence on generator is given. The efficiency of the overall system is here investigated and an optimal topology is selected. Since the EGS operates very often under low load which does not exceed in average more than 30% of the rated permanent load, a new topology of converter of EGS with high efficiency and low cost is suggested and studied theoretically and experimentally in the paper.

  9. 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.

  10. Converter-fed subsea motor drives

    SciTech Connect

    Raad, R.O.; Raphael, H.B.; Henriksen, T.; Hadler-Jacobsen, A.

    1996-09-01

    A subsea adjustable-speed motor fed via a long cable in range of several tens of kilometers between the converter and the motor are analyzed by simulations. Due to resonance, one critical frequency range occurs where significant generation of harmonics from the inverter should be avoided. A voltage source inverter is more feasible than a current source inverter since it is easier to modify the output waveform in order to avoid resonance problems. The resistive voltage drop in the long cable reduces the air-gap torque of the motor particular at low frequencies. This causes a problem for the start-up of the motor due to stiction torque. A start-up strategy is envisaged which is a compromise between voltage boost, inverter current, and transformer core dimensions. In normal operation mode the inverter voltage is proportional to the frequency. An open speed lop is used which keeps the system stable for potential load variations. The results from a 1-MW full-scale system test are summarized.

  11. 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.

  12. Analog-to-digital converter

    NASA Technical Reports Server (NTRS)

    Lewyn, L. L. (inventor)

    1965-01-01

    An analog to digital converter circuit arrangement is reported that is suitable for use in ultra fast pulse height analysis. The circuit uses series connected tunnel diodes to quantize a voltage signal into discrete levels.

  13. Radiation tolerant power converter controls

    NASA Astrophysics Data System (ADS)

    Todd, B.; Dinius, A.; King, Q.; Uznanski, S.

    2012-11-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to significantly increased radiation induced effects in materials close to the accelerator, including the FGC. Recent radiation tests indicate that the current FGC would not be sufficiently reliable. A so-called FGClite is being designed to work reliably in the radiation environment in the post-LS1 era. This paper outlines the concepts of power converter controls for machines such as the LHC, introduces the risks related to radiation and a radiation tolerant project flow. The FGClite is then described, with its key concepts and challenges: aiming for high reliability in a radiation field.

  14. 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.

  15. Harmonic Measure of Critical Curves

    NASA Astrophysics Data System (ADS)

    Bettelheim, E.; Rushkin, I.; Gruzberg, I. A.; Wiegmann, P.

    2005-10-01

    Fractal geometry of critical curves appearing in 2D critical systems is characterized by their harmonic measure. For systems described by conformal field theories with central charge c≤1, scaling exponents of the harmonic measure have been computed by Duplantier [Phys. Rev. Lett. 84, 1363 (2000)PRLTAO0031-900710.1103/PhysRevLett.84.1363] by relating the problem to boundary two-dimensional gravity. We present a simple argument connecting the harmonic measure of critical curves to operators obtained by fusion of primary fields and compute characteristics of the fractal geometry by means of regular methods of conformal field theory. The method is not limited to theories with c≤1.

  16. Harmonic Analysis of the Output Voltage of a Third-Harmonic-Injected Inverter for LSM Drives

    NASA Astrophysics Data System (ADS)

    Shigeeda, Hidenori; Okui, Akinobu; Akagi, Hirofumi

    The superconducting magnetic levitation railway system (MAGLEV) under development in Japan uses a pulse-width-modulation (PWM) inverter for driving a linear synchronous motor (LSM). The inverter output voltage contains non-negligible harmonics which cause harmonic resonances in the LSM system, and therefore harmonics of the output voltage have been analyzed in order to control such harmonic resonances. This paper applies a third-harmonic injection method to the inverter for the purpose of enhancing the output voltage without changing the circuit configuration. It performs harmonic analysis of the output voltage of the inverter based on the third-harmonic injection. Validity of the harmonic analysis is verified by computer simulation.

  17. Growth of nonlinear optical ?-glycine crystals

    NASA Astrophysics Data System (ADS)

    Bhat, M. Narayan; Dharmaprakash, S. M.

    2002-03-01

    Bulk crystals of ?-glycine have been grown at ambient temperature from aqueous solution in the presence of small amount of sodium chloride. The chemical composition of the grown crystal was determined by CHN analysis and infrared spectroscopy. The ?-phase was confirmed by powder XRD, single crystal XRD and differential scanning calorimetry. It was observed that ?-glycine generates second harmonic frequency of an Nd:YAG laser operating at 1064 nm. The second harmonic sconversion efficiency of ?-glycine is comparable with that of potassium dihydrogen phosphate.

  18. 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.

  19. Localization and vector spherical harmonics

    NASA Astrophysics Data System (ADS)

    von Brecht, James H.

    2016-01-01

    This paper establishes the following localization property for vector spherical harmonics: a wide class of non-local, vector-valued operators reduce to local, multiplication-type operations when applied to a vector spherical harmonic. As localization occurs in a very precise, quantifiable and explicitly computable fashion, the localization property provides a set of useful formulae for analyzing vector-valued fractional diffusion and non-local differential equations defined on S d - 1. As such analyses require a detailed understanding of operators for which localization occurs, we provide several applications of the result in the context of non-local differential equations.

  20. Explosive crystallization of PZT microstructures by femtosecond infrared radiation

    NASA Astrophysics Data System (ADS)

    Elshin, A. S.; Firsova, N. Yu; Emelianov, V. I.; Pronin, I. P.; Senkevich, S. V.; Zhigalina, O. M.; Mishina, E. D.; Sigov, A. S.

    2015-12-01

    The features of microstructure crystallization into perovskite phase in lead zirconate titanate film by femtosecond laser radiation of near-infrared range were discussed. In-situ crystallization kinetics by method of second harmonic generation (SHG) was studied. The presence of several types of crystallization was shown, including ultra-fast (explosive) crystallization occurring immediately after the start of exposure, and slow (self-sustaining) crystallization, occurring after termination of exposure. The advantage of the second-harmonic generation microscopy for the study of annealed microstructures was shown. The morphology of microstructures was investigated by transmission electron microscopy (TEM).

  1. 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-synchronizing harmonic tracking, intelligence and robustness of the controller, optimum Idc value, minimal converter losses, and high speed and low dc energy requirement of the CSC, are the main features of the proposed active filter system. Simulation results using the EMTDC simulation package are presented to validate the effectiveness of the proposed modular active filter system. (Abstract shortened by UMI.)

  2. High-order harmonic generation in plasmas from nanoparticle and mixed metal targets at 1-kHz repetition rate

    NASA Astrophysics Data System (ADS)

    Wstmann, Michael; Redkin, Pavel V.; Zheng, Jiaan; Witte, Henrik; Ganeev, Rashid A.; Zacharias, Helmut

    2015-07-01

    High-order harmonic generation in laser-produced plasmas from nanoparticle and mixed metal targets is studied using a femtosecond Ti:sapphire laser operating at 1-kHz repetition rate. Mixed plasmas from brass and plasmas from nanoparticles (Al, carbon) are investigated and compared to their monatomic counterparts of Zn, Cu, and Al. The dependence on the delay between the heating ablation pulse and the driving converting pulse is studied for a light (carbon) and a heavy atom (silver) target. Further, we report on a comparative measurement of the efficiencies and the photon flux from argon gas harmonics and carbon plasma harmonics. For our conditions, the 13th harmonic is generated in a carbon plasma with an efficiency of ? = 5.3 10-7 and yields a flux of about 9.8 1010 photons s-1, about 40 % higher than the corresponding harmonic flux in Ar gas under otherwise identical conditions.

  3. Annular symmetry nonlinear frequency converters.

    PubMed

    Kasimov, Dror; Arie, Ady; Winebrand, Emil; Rosenman, Gil; Bruner, Ariel; Shaier, Pnina; Eger, David

    2006-10-01

    We present a new type of two-dimensional nonlinear structure for quasi-phase matching. This structure has continuous rotational symmetry, and in contrary to the commonly used periodic structures, is not lattice shaped and has no translation symmetry. It is shown that this annular symmetry structure possesses interesting phase matching attributes that are significantly different than those of periodic structures. In particular, it enables simultaneous phase-matched frequency doubling of the same pump into several different directions. Moreover, it has extremely wide phase-mismatch tolerance, since a change in the phase matching conditions does not change the second harmonic power, but only changes its propagation direction. Several structures were fabricated using either the indirect e-beam method in LiNbO(3) or the electric field poling method in stoichiometric LiTaO(3), and their conversion efficiencies, as well as angular and thermal dependencies, were characterized by second harmonic generation. PMID:19529321

  4. Three-dimensional structural imaging of starch granules by second-harmonic generation circular dichroism.

    PubMed

    Zhuo, G-Y; Lee, H; Hsu, K-J; Huttunen, M J; Kauranen, M; Lin, Y-Y; Chu, S-W

    2014-03-01

    Chirality is one of the most fundamental and essential structural properties of biological molecules. Many important biological molecules including amino acids and polysaccharides are intrinsically chiral. Conventionally, chiral species can be distinguished by interaction with circularly polarized light, and circular dichroism is one of the best-known approaches for chirality detection. As a linear optical process, circular dichroism suffers from very low signal contrast and lack of spatial resolution in the axial direction. It has been demonstrated that by incorporating nonlinear interaction with circularly polarized excitation, second-harmonic generation circular dichroism can provide much higher signal contrast. However, previous circular dichroism and second-harmonic generation circular dichroism studies are mostly limited to probe chiralities at surfaces and interfaces. It is known that second-harmonic generation, as a second-order nonlinear optical effect, provides excellent optical sectioning capability when combined with a laser-scanning microscope. In this work, we combine the axial resolving power of second-harmonic generation and chiral sensitivity of second-harmonic generation circular dichroism to realize three-dimensional chiral detection in biological tissues. Within the point spread function of a tight focus, second-harmonic generation circular dichroism could arise from the macroscopic supramolecular packing as well as the microscopic intramolecular chirality, so our aim is to clarify the origins of second-harmonic generation circular dichroism response in complicated three-dimensional biological systems. The sample we use is starch granules whose second-harmonic generation-active molecules are amylopectin with both microscopic chirality due to its helical structure and macroscopic chirality due to its crystallized packing. We found that in a starch granule, the second-harmonic generation for right-handed circularly polarized excitation is significantly different from second-harmonic generation for left-handed one, offering excellent second-harmonic generation circular dichroism contrast that approaches 100%. In addition, three-dimensional visualization of second-harmonic generation circular dichroism distribution with sub-micrometer spatial resolution is realized. We observed second-harmonic generation circular dichroism sign change across the starch granules, and the result suggests that in thick biological tissue, second-harmonic generation circular dichroism arises from macroscopic molecular packing. Our result provides a new method to visualize the organization of three-dimensional structures of starch granules. The second-harmonic generation circular dichroism imaging method expands the horizon of nonlinear chiroptical studies from simplified surface/solution environments to complicated biological tissues. PMID:24392849

  5. Binary/BCD-to-ASCII data converter

    NASA Technical Reports Server (NTRS)

    Miller, A. J.

    1977-01-01

    Converter inputs multiple precision binary words, converts data to multiple precision binary-coded decimal, and routes data back to computer. Converter base can be readily changed without need for new gate structure for each base changeover.

  6. 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.

  7. 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

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

    PubMed

    Matko, Vojko; Milanovi?, 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 H to 2-560 kHz. PMID:25325334

  9. Harmonic resolution as a holographic quantum number

    SciTech Connect

    Bousso, Raphael

    2004-01-31

    The Bekenstein bound takes the holographic principle into the realm of flat space, promising new insights on the relation of non-gravitational physics to quantum gravity. This makes it important to obtain a precise formulation of the bound. Conventionally, one specifies two macroscopic quantities, mass and spatial width, which cannot be simultaneously diagonalized. Thus, the counting of compatible states is not sharply defined. The resolution of this and other formal difficulties leads naturally to a definition in terms of discretized light-cone quantization. In this form, the area difference specified in the covariant bound converts to a single quantum number, the harmonic resolution K. The Bekenstein bound then states that the Fock space sector with K units of longitudinal momentum contains no more than exp(2 pi^2 K) independent discrete states. This conjecture can be tested unambiguously for a given Lagrangian, and it appears to hold true for realistic field theories, including models arising from string compactifications. For large K, it makes contact with more conventional but less well-defined formulations.

  10. 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.

  11. A harmonic analysis of lunar gravity

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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.

  12. 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 beamone turns on when the other turns off, at different harmonicsso 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.

  13. Harmonic undulator radiations with constant magnetic field

    NASA Astrophysics Data System (ADS)

    Jeevakhan, Hussain; Mishra, G.

    2015-01-01

    Harmonic undulators has been analysed in the presence of constant magnetic field along the direction of main undulator field. The spectrum modifications in harmonic undulator radiations and intensity degradation as a function of constant magnetic field magnitude at fundamental and third harmonics have been evaluated with a numerical integration method and generalised Bessel function. The role of harmonic field to overcome the intensity reduction due to constant magnetic field and energy spread in electron beam has also been demonstrated.

  14. Harmonic generation from indium-rich plasmas

    SciTech Connect

    Ganeev, R. A.; Kulagin, I. A.; Singhal, H.; Naik, P. A.; Arora, V.; Chakravarty, U.; Chakera, J. A.; Khan, R. A.; Raghuramaiah, M.; Gupta, P. D.; Redkin, P. V.

    2006-12-15

    An experimental study of high-order harmonic generation in In, InSb, InP, and InGaP plasmas using femtosecond laser radiation with variable chirp is presented. Intensity enhancement of the 13th and 21st harmonics compared to the neighboring harmonics by a factor of 200 and 10, respectively, is observed. It is shown that the harmonic spectrum from indium-containing plasma plumes can be considerably modified by controlling the chirp of the driving laser pulse.

  15. 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.

  16. Stirling Converters For Solar Power

    NASA Technical Reports Server (NTRS)

    Shaltens, Richard K.; Schreiber, Jeffrey G.

    1993-01-01

    Two designs expected to meet long-term goals for performance and cost. Proposed for advanced systems to convert solar thermal power to electrical power. Each system, designed to operate with 11-m-diameter paraboloidal reflector, includes solar-energy receiver, liquid-metal heat-transport subsystem, free-piston Stirling engine, cooling subsystem, alternator or generator coupled directly or indirectly to commercial electric-power system, and control and power-conditioning circuitry. System converts approximately 75 kW of input solar thermal power falling on collector to about 25 kW of output electrical power.

  17. Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

    SciTech Connect

    Richman, B.A.; Bisson, S.E.; Trebino, R.

    1998-04-01

    Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle versus wavelength to second order, we efficiently doubled tunable fundamental light near 660nm over a range of 80nm, using a 4-mm-long type I {beta}-barium borate crystal without tuning the crystal angle. Another set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 {mu}rad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10{percent}. {copyright} {ital 1998} {ital Optical Society of America}

  18. Dynamics of injection locking in a solid-state laser with intracavity second-harmonic generation

    SciTech Connect

    Zolotoverkh, I I; Lariontsev, E G

    2000-09-30

    The dynamics of oscillation in a solid-state laser with intracavity second-harmonic generation under the influence of an external signal at the second-harmonic frequency injected into its cavity in the presence of feedback at the double frequency is theoretically studied. Boundaries of the regions of injection locking for three stationary laser states differing in the nonlinear phase incursion caused by radiation conversion into the second harmonic are found. Relaxation oscillations in the stationary state of injection locking are studied. It is shown that the second relaxation frequency, which is related to phase perturbations of the second harmonic and perturbations of the phase difference of waves in a nonlinear crystal, is excited in a single-mode solid-state laser in addition to the fundamental frequency of relaxation oscillations. Conditions are found under which relaxation oscillations at the second relaxation frequency are excited. (lasers)

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

    NASA Astrophysics Data System (ADS)

    Rakowski, R.; Barna, A.; Suta, T.; Bohus, J.; Fldes, I. B.; Szatmri, S.; Miko?ajczyk, J.; Bartnik, A.; Fiedorowicz, H.; Verona, C.; Verona Rinati, G.; Margarone, D.; Nowak, T.; Rosi?ski, M.; Ry?, L.

    2014-12-01

    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.

  20. Continuous-wave ultraviolet emission through fourth-harmonic generation in a whispering-gallery resonator.

    PubMed

    Moore, Jeremy; Tomes, Matthew; Carmon, Tal; Jarrahi, Mona

    2011-11-21

    We experimentally demonstrate continuous-wave ultraviolet emission through forth-harmonic generation in a millimeter-scale lithium niobate whispering-gallery resonator pumped with a telecommunication-compatible infrared source. The whispering-gallery resonator provides four spectral lines at ultraviolet, visible, near-infrared and infrared, which are equally spaced in frequency via the cascaded-harmonic process and span a 2-octave frequency band. Our technique relies on a variable crystal poling and high transverse order of the modes for phase-matching and a resonator quality factor of over 10(7) to allow cascaded-harmonic generation up to the fourth-harmonic at input pump powers as low as 200 mW. The compact size of the whispering gallery resonator pumped at telecommunication-compatible infrared wavelengths and the low pump power requirement make our device a promising ultraviolet light source for information storage, microscopy, and chemical analysis. PMID:22109440

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

    PubMed

    Rakowski, R; Barna, A; Suta, T; Bohus, J; Fldes, I B; Szatmri, S; Miko?ajczyk, J; Bartnik, A; Fiedorowicz, H; Verona, C; Verona Rinati, G; Margarone, D; Nowak, T; Rosi?ski, M; Ry?, L

    2014-12-01

    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. PMID:25554270

  2. 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.

  3. 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.

  4. Electrically heatable catalytic converter insert

    SciTech Connect

    Whittenberger, W.A.

    1992-09-15

    This patent describes an electrically heatable catalytic converter insert for insertion in an exhaust line from an internal combustion engine, it comprises: a catalyst bearing corrugated thin metal polycellular honeycomb monolith dimensioned and having a circular configuration for placement within an exhaust line.

  5. Hybrid-mode thermionic converter

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.; Britt, E. J.

    1976-01-01

    Converter's collector electrode has uniform low work-function surface and operates at sufficiently low temperature to produce negligible electron emission. Emitter electrode has main region which has intermediate work-function and auxiliary region which has relatively high work-function surface.

  6. Converting accounts receivable into cash.

    PubMed

    Folk, M D; Roest, P R

    1995-09-01

    In recent years, increasing numbers of healthcare providers have converted their accounts receivable into cash through a process called securitization. This practice has gained popularity because it provides a means to raise capital necessary to healthcare organizations. Although securitization transactions can be complex, they may provide increased financial flexibility to providers as they prepare for continuing change in the healthcare industry. PMID:10145096

  7. Simplified Digital Down-Converters

    NASA Technical Reports Server (NTRS)

    Sigman, Elliott H.

    1995-01-01

    Design of digital frequency down-converters simplified by eliminating need for both high-speed number-controlled oscillators (NCOs) and mixer-multipliers, and implementing functions via multiplication coefficients of finite-impulse-response (FIR) filters. Simplification depends on particular choices of operating frequencies. Simplified designs implemented with commercial FIR integrated circuits.

  8. CONVERTING ABANDONED LANDS TO CROPLAND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of economic conditions, areas of cropland in Ukraine have been left unused for several years. These abandoned lands are now infested with perennial weeds. Producers are interested in converting these lands back to cropland with no-till systems to preserve soil benefits gained by not tillin...

  9. Charge-pump voltage converter

    DOEpatents

    Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    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.

  10. Waveguide harmonic damper for klystron amplifier.

    SciTech Connect

    Kang, Y.

    1998-10-27

    A waveguide harmonic damper was designed for removing the harmonic frequency power from the klystron amplifiers of the APS linac. Straight coaxial probe antennas are used in a rectangular waveguide to form a damper. A linear array of the probe antennas is used on a narrow wall of the rectangular waveguide for damping klystron harmonics while decoupling the fundamental frequency in dominent TE{sub 01} mode. The klystron harmonics can exist in the waveguide as waveguide higher-order modes above cutoff. Computer simulations are made to investigate the waveguide harmonic damping characteristics of the damper.

  11. Diamond turning of L-arginine phosphate, a new organic nonlinear crystal.

    PubMed

    Fuchs, B A; Syn, C K; Velsko, S P

    1989-10-15

    We have demonstrated that single point diamond turning can be used to generate high optical quality finished surfaces on a new organic nonlinear crystal, L-arginine phosphate (LAP). The proper choice of cutting conditions can produce surfaces with <5-A rms local roughness. Local softening or melting near the cutting tool tip may play a key role in the machining process by ensuring that material is removed by ductile cutting rather than brittle fracture. At the same time, the low melting temperature of LAP makes lubrication and cooling especially important to prevent extensive melting and tool fouling. In spite of the presence of a weak cleavage plane in LAP, the surface quality is relatively insensitive to crystallographic orientation. Tool wear is apparently negligible, so that surface flatness is governed by the stability of the diamond turning machine. These results suggest that it may be possible to fabricate large aperture LAP harmonic converters for use in inertial confinement fusion lasers. PMID:20555896

  12. Diamond turning of L-arginine phosphate, a new organic crystal

    SciTech Connect

    Fuchs, B.A.; Syn, K.; Velsko, S.P. )

    1989-10-15

    We have demonstrated that single point diamond turning can be used to generate high optical quality finished surfaces on a new organic nonlinear crystal, L-arginine phosphate (LAP). The proper choice of cutting conditions can produce surfaces with {lt}5-A rms local roughness. Local softening or melting near the cutting tool tip may play a key role in the machining process by ensuring that material is removed by ductile cutting rather than brittle fracture. At the same time, the low melting temperature of LAP makes lubrication and cooling especially important to prevent extensive melting and tool fouling. In spite of the presence of a weak cleavage plane in LAP, the surface quality is relatively insensitive to crystallographic orientation. Tool wear is apparently negligible, so that surface flatness is governed by the stability of the diamond turning machine. These results suggest that it may be possible to fabricate large aperture LAP harmonic converters for use in inertial confinement fusion lasers.

  13. A Proposal of a Power Distortion Compensator Using a Matrix Converter

    NASA Astrophysics Data System (ADS)

    Tamada, Shunsuke; Itoh, Jun-Ichi

    Recently, renewable resources supplies, such as fuel cells, photovoltaic cells, wind power and engine generators, for distributed power system have been studied intensely. Conventional compensators with switching devices are constructed based on a voltage source inverter using six arms. Therefore, conventional power quality compensators require a large electrolytic capacitor in the dc link part of the equipment. The use of a large capacitor hinders downsizing efforts and the lowering of equipment costs. Direct converters, which do not have a large electrolytic capacitor and an initial charge circuit, can be used to realize downsizing and lowering of equipment costs, when compared with conventional converters. This paper proposes one of new applications of a matrix converter to a PM generator for power quality compensation, such as reactive power compensation, harmonic current and power interruption. The novel point of this work is that the matrix converter provides reactive power with harmonic current. Simulated and experimental results confirm that the matrix converter can maintain high performance as same as a conventional active filter and an uninterruptible power supply (UPS).

  14. EMI Reduction by Spread-Spectrum Clocking in Digitally-Controlled DC-DC Converters

    NASA Astrophysics Data System (ADS)

    Mori, Ibuki; Yamada, Yoshihisa; Wibowo, Santhos A.; Kono, Masashi; Kobayashi, Haruo; Fujimura, Yukihiro; Takai, Nobukazu; Sugiyama, Toshio; Fukai, Isao; Onishi, Norihisa; Takeda, Ichiro; Matsuda, Jun-Ichi

    This paper proposes spread-spectrum clock modulation algorithms for EMI reduction in digitally-controlled DC-DC converters. In switching regulators using PWM, switching noise and harmonic noise concentrated in a narrow spectrum around the switching frequency can cause severe EMI. Spread-spectrum clock modulation can be used to minimize EMI. In conventional switching regulators using analog control it is very difficult to realize complex spread-spectrum clocking, however this paper shows that it is relatively easy to implement spread-spectrum EMI-reduction using digital control. The proposed algorithm was verified using a power converter simulator (SCAT).

  15. Data harmonization and model performance

    NASA Astrophysics Data System (ADS)

    The Joint Committee on Urban Storm Drainage of the International Association for Hydraulic Research (IAHR) and International Association on Water Pollution Research and Control (IAWPRC) was formed in 1982. The current committee members are (no more than two from a country): B. C. Yen, Chairman (USA); P. Harremoes, Vice Chairman (Denmark); R. K. Price, Secretary (UK); P. J. Colyer (UK), M. Desbordes (France), W. C. Huber (USA), K. Krauth (FRG), A. Sjoberg (Sweden), and T. Sueishi (Japan).The IAHR/IAWPRC Joint Committee is forming a Task Group on Data Harmonization and Model Performance. One objective is to promote international urban drainage data harmonization for easy data and information exchange. Another objective is to publicize available models and data internationally. Comments and suggestions concerning the formation and charge of the Task Group are welcome and should be sent to: B. C. Yen, Dept. of Civil Engineering, Univ. of Illinois, 208 N. Romine St., Urbana, IL 61801.

  16. Axisymmetric generalized harmonic evolution code

    NASA Astrophysics Data System (ADS)

    Sorkin, Evgeny

    2010-04-01

    We describe the first axisymmetric numerical code based on the generalized harmonic formulation of the Einstein equations, which is regular at the axis. We test the code by investigating gravitational collapse of distributions of complex scalar field in a Kaluza-Klein spacetime. One of the key issues of the harmonic formulation is the choice of the gauge source functions, and we conclude that a damped-wave gauge is remarkably robust in this case. Our preliminary study indicates that evolution of regular initial data leads to formation both of black holes with spherical and cylindrical horizon topologies. Intriguingly, we find evidence that near threshold for black hole formation the number of outcomes proliferates. Specifically, the collapsing matter splits into individual pulses, two of which travel in the opposite directions along the compact dimension and one which is ejected radially from the axis. Depending on the initial conditions, a curvature singularity develops inside the pulses.

  17. Axisymmetric generalized harmonic evolution code

    SciTech Connect

    Sorkin, Evgeny

    2010-04-15

    We describe the first axisymmetric numerical code based on the generalized harmonic formulation of the Einstein equations, which is regular at the axis. We test the code by investigating gravitational collapse of distributions of complex scalar field in a Kaluza-Klein spacetime. One of the key issues of the harmonic formulation is the choice of the gauge source functions, and we conclude that a damped-wave gauge is remarkably robust in this case. Our preliminary study indicates that evolution of regular initial data leads to formation both of black holes with spherical and cylindrical horizon topologies. Intriguingly, we find evidence that near threshold for black hole formation the number of outcomes proliferates. Specifically, the collapsing matter splits into individual pulses, two of which travel in the opposite directions along the compact dimension and one which is ejected radially from the axis. Depending on the initial conditions, a curvature singularity develops inside the pulses.

  18. 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.

  19. Characteristics of an equidistant firing system in 12-pulse converter bridges for HVDC

    NASA Astrophysics Data System (ADS)

    Juslin, K.; Laiho, Y.; Vauhkonen, V.

    1981-05-01

    The construction of a simulation model for a twelve pulse HVDC transmission line is discussed. The realized equidistant pulse phase control system is suitable for the operation in weak or strongly unbalanced ac systems from the viewpoint of harmonic instability and suppression of abnormal harmonic currents. The phase of the firing pulses is proportional to an absolute level of the control voltage, and the operation with a constant control angle is possible. The synchronism with an ac system is guaranteed by a phase-locked loop, not by the main control loop. Thus quick and ideal response is obtaind. The measurements show that this kind of grid conrol is stable also in many faulty conditions. Abnormal harmonic generation of the converter is very small compared with the traditional systems by utilizing this kind of grid control.

  20. Harmonic auroral kilometric radiation of natural origin

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1982-01-01

    When the ISIS 1 satellite passes through the auroral kilometric radiation (AKR) source region the sounder receiver often detects harmonic bands of radiation associated with the fundamental AKR band. These harmonic components were earlier attributed to a nonlinear instrumental response to the strong wide-band bursty AKR fundamental signal. Evidence is here presented that indicates that these harmonics are of natural origin, namely: (1) all the harmonic signals are sometimes observed to have nearly the same bandwidth, (2) when the fundamental signal has two components the harmonic signal sometimes corresponds to the weaker rather than the stronger component, (3) a weak harmonic can be observed to be associated with a weak fundamental, and (4) a 'harmonic' signal can be observed when there is no fundamental.

  1. Nonclassical states of the second optical harmonic in the presence of self-action

    NASA Technical Reports Server (NTRS)

    Chirkin, A. S.; Korolkova, N. V.

    1993-01-01

    The quantum theory of coherent radiation frequency doubling in crystals with quadratic and cubic optical nonlinearities is developed. The possibility of producing the quadrature-squeezed state of the second harmonic (SH) field is shown. The nonclassical SH states arise due to self-action effect.

  2. Observation of the second harmonic generation pumped by microscopic to extraterrestrial incoherent light sources

    NASA Astrophysics Data System (ADS)

    Tamoauskas, Gintaras

    2011-10-01

    I report on the experimental demonstration of the second harmonic generation in bulk nonlinear crystals excited by light emitting diode, halogen lamp and the Sun. Practical application for measurement of autocorrelation functions of incoherent non-laser driven sources via second order nonlinearity is demonstrated for the first time.

  3. Venus topography - A harmonic analysis

    NASA Astrophysics Data System (ADS)

    Bills, B. G.; Kobrick, M.

    1985-01-01

    A model of Venusian global topography has been obtained by fitting an eighteenth-degree harmonic series to Pioneer Venus orbiter radar altimeter data. The mean radius is (6051.45 + or - 0.04) km. The corresponding mean density is (5244.8 + or 0.5) kg/cu m. The center of figure is displaced from the center of mass by (0.339 + or - 0.088) km towards (6.6 + or 10.1) deg N, (148. 8 + or - 7.7) deg. The figure of Venus is distinctly triaxial, but the orientation and magnitudes of the principal topographic axes correlate rather poorly with the gravitational principal axes. However, the higher-degree harmonics of topography and gravity are significantly correlated. The topographic variance spectrum of Venus is very similar in form to those of the moon, Mars, and especially earth. It is suggested that this spectral similarity simply reflects a statistical balance between constructional and degradational geomorphic proceses. Venus and earth are particularly similar (and differ from the moon and Mars) in that the larger bodies both exhibit a significant low degree deficit (relative to the extrapolated trend of the higher harmonics).

  4. 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.

  5. 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.

  6. Second-harmonic imaging from a modulated domain structure.

    PubMed

    Zhang, Yong; Wang, Fuming; Geren, Katrina; Zhu, S N; Xiao, Min

    2010-01-15

    We present a new second-harmonic (SH) imaging technique to study the domains in a hexagonally poled LiTaO(3) nonlinear photonic crystal by using a femtosecond laser. By detecting the SH images at different planes, the distribution of the 180 degrees -inverted ferroelectric domains can be characterized, and the contributions of different nonlinear tensor components, modulated differently in the domain structure, can be selectively determined. Fundamental understanding and potential applications of such SH imaging techniques for the inverted nonlinear domain structures are presented and discussed. PMID:20081960

  7. 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).

  8. 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.

  9. 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.

  10. 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.

  11. Vibration converter with magnetic levitation

    NASA Astrophysics Data System (ADS)

    Gladilin, A. V.; Pirogov, V. A.; Golyamina, I. P.; Kulaev, U. V.; Kurbatov, P. A.; Kurbatova, E. P.

    2015-05-01

    The paper presents a mathematical model, the results of computational and theoretical research, and the feasibility of creating a vibration converter with full magnetic levitation in the suspension of a high-temperature superconductor (HTSC). The axial and radial stability of the active part of the converter is provided by the interaction of the magnetic field of ring-shaped permanent magnets and a hollow cylinder made of the ceramic HTSC material. The force is created by a system of current-carrying coils whose magnetic field is polarized by permanent magnets and interacts with induced currents in the superconducting cylinder. The case of transition to the superconducting state of HTSC material in the field of the permanent magnets (FC mode) is considered. The data confirm the outlook for the proposed technical solutions.

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

    PubMed Central

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

    2010-01-01

    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 oscillators 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. PMID:20733934

  13. 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.

  14. Mode conversion and absorption of fast waves at high ion cyclotron harmonics in inhomogeneous magnetic fields

    SciTech Connect

    Cho, Suwon; Kwak, Jong-Gu

    2014-04-15

    The propagation and absorption of high harmonic fast waves is of interest for non-inductive current drives in fusion experiments. The fast wave can be coupled with the ion Bernstein wave that propagates in the high magnetic field side of an ion cyclotron harmonic resonance layer. This coupling and the absorption are analyzed using the hot plasma dispersion relation and a wave equation that was converted from an approximate dispersion relation for the case where ?{sub i}=k{sub ?}{sup 2}?{sub i}{sup 2}/2?1 (where k{sub ?} is the perpendicular wave number and ?{sub i} is the ion Larmor radius). It is found that both reflection and conversion may occur near the harmonic resonance layer but that they decrease rapidly, giving rise to a sharp increase in the absorption as the parallel wave number increases.

  15. Plasmonic grating as a nonlinear converter-coupler.

    PubMed

    Talebi, Nahid; Shahabadi, Mahmoud; Khunsin, Worawut; Vogelgesang, Ralf

    2012-01-16

    The paper introduces a wavelength converter composed of a metallic finite 2-dimensional particle grating on top of an optical waveguide. The particles sustain plasmonic resonances which will result in the near-field enhancement and therefore, high conversion efficiency. Due to near-field interaction of the grating field with the propagating modes of the waveguide, the generated third harmonic wave is phase-matched to a propagating mode of the waveguide, while the fundamental frequency component is not coupled into the output waveguide of the structure. The performance of this structure is numerically investigated using a full-wave transmission line method for the linear analysis and a three-dimensional finite-difference time-domain method for the nonlinear analysis. PMID:22274484

  16. Effects of geomagnetically-induced currents on HVDC converter operation

    SciTech Connect

    Mohan, N.; Albertson, V.D.; Bahrman, M.P.; Kappenman, K.G.; Speak, T.J.

    1982-11-01

    Electrons and protons emitted by a solar flare can be captured by the Earth's magnetic field. The resulting transient in the geomagnetic field can produce quasi-dc currents in electric power systems. These geomagnetically-induced currents (GIC) in excess of 100 amps have been measured in the transformer neutral leads. With the practice of using EHV and UHV lines for transmitting ac power over long distances and because the systems are more solidly grounded, the problems posed by GIC have become more severe. This paper presents the consequences of transformer halfcycle saturation on the operation of HVDC converter terminals. A detailed computer simulation of the Square Butte HVDC system reveals that the large values of GIC can cause enough distortion in the ac system voltage at the inverter end to prevent normal system operation. Moreover, the amount of harmonics generated could overload the ac as well as the dc-side filters.

  17. Converter Circuit Voltage-Voltage Investigation for Power Calibrator

    NASA Astrophysics Data System (ADS)

    Fomichev, Yu M.; Silushkin, S. V.; Mylnikova, T. S.

    2016-01-01

    The paper presents possible circuits to construct a voltage-voltage converter for the calibrator of fictitious power. The problems of circuit solutions were experimentally identified, and the ways of their elimination were found. One of the main problems of convectors is to provide small harmonic distortions and additional phase shift. The use of deep negative instantaneous value feedback helps to provide the desired level of nonlinear distortions and to reduce the phase shift. Corrective circuits are used to ensure the stability of the transducer at greater depths of the feedback; the half-period average value or rms value feedback is used to ensure the stability and accuracy of conversion. However, the accuracy of the power calibrator can be upgraded and its work for various types of loads can be ensured by means of application follower circuit with modern electronic components which are also discussed in the paper.

  18. Thermal optimization of second harmonic generation at high pump powers.

    PubMed

    Sahm, Alexander; Uebernickel, Mirko; Paschke, Katrin; Erbert, Gtz; Trnkle, Gnther

    2011-11-01

    We measure the temperature distribution of a 3 cm long periodically poled LiNbO? crystal in a single-pass second harmonic generation (SHG) setup at 488 nm. By means of three resistance heaters and directly mounted Pt100 sensors the crystal is subdivided in three sections. 9.4 W infrared pump light and 1.3 W of SHG light cause a de-homogenized temperature distribution of 0.2 K between the middle and back section. A sectional offset heating is used to homogenize the temperature in those two sections and thus increasing the conversion efficiency. A 15% higher SHG output power matching the prediction of our theoretical model is achieved. PMID:22109182

  19. Harmonic holography: a new holographic principle.

    PubMed

    Pu, Ye; Centurion, Martin; Psaltis, Demetri

    2008-02-01

    The process of second harmonic generation (SHG) has a unique property of forming a sharp optical contrast between noncentrosymmetric crystalline materials and other types of material, which is a highly valuable asset for contrast microscopy. The coherent signal obtained through SHG also allows for the recording of holograms at high spatial and temporal resolution, enabling whole-field four-dimensional microscopy for highly dynamic microsystems and nanosystems. Here we describe a new holographic principle, harmonic holography (H(2)), which records holograms between independently generated second harmonic signals and reference. We experimentally demonstrate this technique with digital holographic recording of second harmonic signals upconverted from an ensemble of second harmonic generating nanocrystal clusters under femtosecond laser excitation. Our results show that harmonic holography is uniquely suited for ultrafast four-dimensional contrast microscopy. PMID:18239691

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

    NASA Astrophysics Data System (ADS)

    Parvini, T. S.; Tehranchi, M. M.; Hamidi, S. M.; Sarkarati, S.

    2015-11-01

    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 LiNbO3 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.

  1. 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).

  2. Network models enlighten harmonics investigations

    SciTech Connect

    Sachs, U.; Tyll, H.; Unger, C.

    1996-04-01

    This article describes how, with the increasing use of controlled power electronic devices, the computer-aided estimation of future harmonic loads is playing an increasingly important role in the planning of network expansion projects and in the connection of new loads. A suitable means of representing network elements and complete network components across the entire frequency range under investigation is required, for the various circuit configurations. This is necessary in order to conduct investigations of this nature and to achieve realistic results within a reasonable time period.

  3. Making space for harmonic oscillators

    SciTech Connect

    Michelotti, Leo; /Fermilab

    2004-11-01

    If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.

  4. 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 ?=517 nm in subwavelength silicon-based nanoplasmonic waveguides at an unprecedented conversion efficiency of 2.310^{-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 ?=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. PMID:26196643

  5. The harmonic oscillator behind all aberrations

    SciTech Connect

    Wolf, Kurt Bernardo

    2010-12-23

    The group-theoretical structure of the harmonic oscillator appears in many guises. Originally developed by Marcos Moshinsky among several others for applications in nuclear physics, we point out here that the harmonic oscillator structure appears in aberrations of geometric optics, particularly in their classification by rank, symplectic spin and weight. And further, the finite harmonic oscillator appears again in the nonlinear transformations of finite Hamiltonian systems, when applied to the parallel processing of signals.

  6. 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.

  7. High harmonic generation spectroscopy of hydrocarbons

    NASA Astrophysics Data System (ADS)

    Vozzi, C.; Torres, R.; Negro, M.; Brugnera, L.; Siegel, T.; Altucci, C.; Velotta, R.; Frassetto, F.; Poletto, L.; Villoresi, P.; De Silvestri, S.; Stagira, S.; Marangos, J. P.

    2010-12-01

    We have demonstrated the ability of few-cycle midinfrared intense laser pulses to produce extended harmonic spectra (?45 eV) suitable for high harmonic spectroscopy in aligned hydrocarbons with ionization potentials in the range 9.07-11.52 eV. Modulations in the spectra measured with different alignment angles show signatures of the molecular structure. These results pave the way for the extension of high harmonic spectroscopy to complex biomolecules.

  8. Higher harmonic control for rotary wing aircraft

    NASA Technical Reports Server (NTRS)

    Gupta, B. P.; Logan, A. H.; Wood, E. R.

    1984-01-01

    Higher Harmonic Control reduces helicopter airframe vibration through the exercise of rotor blade pitch control at frequencies that are higher harmonics of rotor rotation. Analysis wind tunnel tests and flight tests of this technology with an OH-6A helicopter have led to vibration reduction levels of the order of more than 80 percent. Blade feathering capability at rotor speed harmonics other than the first also promises the improvement of such rotor characteristics as acoustics, aerodynamic efficiency and ground resonance.

  9. 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.

  10. Synthesis, crystal growth and physical characterizations of organic nonlinear optical crystal: Ammonium hydrogen L-malate.

    PubMed

    Boopathi, K; Ramasamy, P

    2014-05-21

    An organic nonlinear optical crystal ammonium hydrogen l-malate (AHM) has been synthesized. Single crystals of AHM have successfully been grown by the slow evaporation solution method. Optically clear single crystals having dimensions up to 2394mm(3) have been grown. Single crystal X-ray diffraction study confirms that the AHM crystallizes in orthorhombic crystal system with space group P212121. The powder X-ray diffraction pattern of the grown crystal has been recorded. FT-IR spectrum was recorded to identify the various functional groups of AHM. The UV-vis-NIR transmission was analyzed for grown crystal. Thermal analysis was performed to find out thermal stability of the compound. Vickers microhardness measurements were carried and also work hardening coefficient has been found. The crystalline perfection of the grown crystal has been analyzed by HRXRD measurements. The second harmonic efficiency of AHM was found to be 1.2 times that of KDP. PMID:24583470

  11. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z. (Knoxville, TN)

    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.

  12. Enhanced harmonic generation in aperiodic optical superlattices

    NASA Astrophysics Data System (ADS)

    Gu, Ben-Yuan; Dong, Bi-Zhen; Zhang, Yan; Yang, Guo-Zhen

    1999-10-01

    We find that harmonic generation can be enhanced with aperiodic optical superlattice (AOS) structures realized by inverting poled ferroelectric domains in sample. The optimal design of the AOS can be achieved with use of the simulated annealing method. The constructed AOSs can implement multiple wavelength second-harmonic generation and the coupled third-harmonic generation with an identical effective nonlinear coefficient. The simulations show that the constructed AOSs can enhance harmonic generation compared with the Fibonacci optical superlattice. The physical origin of this enhancement is ascribed to the constructive interference effect.

  13. Digital control of HVDC converters

    SciTech Connect

    Pilotto, L.A.S.; Roitman, M.; Alves, J.E.R.

    1989-05-01

    This paper presents the project of a completely digital HVDC converter controller based on a 16-bit microcomputer. It was decided to achieve as much as possible by software in order to minimize functions performed by external hardware. The presented design comprises software programmed functions such as a PID current control amplifier, voltage dependent current order limiters and an alpha-minimum symmetrization unit, among others. HVDC control principles are briefly reviewed and a detailed description of both the hardware and software structure of the controller is presented. The digital controller was implemented in an HVDC simulator and several dynamic performance tests demonstrated the efficiency of the proposed methodology.

  14. Liquid-metal magnetohydrodynamic converter

    SciTech Connect

    Aladiev, I.T.; Dikhashidze, M.A.; Dzhamardzhashvili, V.A.; Teplov, S.V.; Tskhvirashvili, D.G.

    1981-06-16

    A liquid-metal magnetohydrodynamic converter is disclosed that is comprised of hydraulically interconnected components as a heat source a two-phase nozzle, a separator, a magnetohydrodynamic generator, a liquid diffuser, and a heat-regenerating means, said components being arranged successively so as to form a loop. The two-phase nozzle is provided with steam-bleeding units located in different sections over its length and having the outlets thereof coupled to steam inlets of the heat-regenerating means. A steam diffuser and a condenser are hydraulically interconnected and coupled to the separator and the steam inlet of the heat-regenerating means, respectively.

  15. Liquid-metal magnetohydrodynamic converter

    SciTech Connect

    Aladiev, I. T.; Dzhamardzhashvili, V. A.

    1981-09-01

    A liquid-metal magnetohydrodynamic converter is described that is comprised of such hydraulically interconnected components as a heat source, a two-phase nozzle, a separator, a liquid diffuser, a liquid metal cooler, a magnetohydrodynamic generator and a means for heating and delivering liquid metal supplied from the cooler, all of said components being arranged successively so as to form a loop. A steam diffuser and a condenser are interconnected and hydraulically coupled to the separator and the means for heating and delivering liquid metal supplied from the cooler, respectively.

  16. Pneumatic analog-to-pulse frequency converter

    NASA Technical Reports Server (NTRS)

    Dustin, M. O.

    1969-01-01

    Pneumatic analog-to-pulse frequency converter circuit has output pulse frequency proportional to the pressure level of the input signal. Converter circuit drives a pneumatic stepping motor and is part of a pneumatic control system for nuclear powered spacecraft.

  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. 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. PMID:26696190

  19. Design, Control, and Modeling of a New Voltage Source Converter for HVDC System

    NASA Astrophysics Data System (ADS)

    Mohan, Madhan; Singh, Bhim; Ketan Panigrahi, Bijaya

    2013-05-01

    Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (?), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.

  20. Hyperincursive Algorithms of Classical Harmonic Oscillator Applied to Quantum Harmonic Oscillator Separable Into Incursive Oscillators

    NASA Astrophysics Data System (ADS)

    Dubois, Daniel M.

    This paper will first survey the hyperincursive and incursive algorithms to discretize the classical harmonic oscillator. These algorithms show stable orbital with the conservation of energy. This paper will then apply these hyperincursive and incursive algorithms to the quantum harmonic oscillator. The hyperincursive quantum harmonic oscillator is separable into two incursive quantum harmonic oscillators. Numerical simulations confirm the stability of these hyperincursive and incursive algorithms.

  1. Retrieving squeezing from classically noisy light in second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Ralph, T. C.; White, A. G.

    1995-05-01

    We report the results of a study of the quantum noise properties of a squeezing system involving a three-level laser pumping two similar second-harmonic-generating crystals. We show that squeezing that has been obscured by intensity and phase noise from the pump laser may be retrieved by difference detection of both second-harmonic outputs. Similarly, the squeezed vacuum formed by combining the two outputs on a 50/50 beam splitter will be squeezed at frequencies that are classically noisy in the individual beams.

  2. Growth and characterization of large CLBO crystals

    NASA Astrophysics Data System (ADS)

    Yuan, Xin; Shen, Guangqiu; Wang, Xiaoqing; Shen, Dezhong; Wang, Guiling; Xu, Zuyan

    2006-07-01

    A high optical quality Cesium lithium borate (CLBO) crystal with dimensions of 146×132×118 mm was grown by the Kyropoulos method. The 4th harmonic generation of a frequency doubled Nd:YAG laser, from 532 to 266 nm, was carried out with a CLBO crystal doubler, and an average output power of 28.4 W was achieved at 266 nm. Polished surfaces were etched to reveal the cracking mechanism of CLBO crystals. Through observation and comparison of the surface etching patterns, it is proved that CLBO crystals crack under chemical attack by water molecules penetrating from the (1 0 0) and (0 1 0) crystallographic planes.

  3. Converting from CVF to AAF

    NASA Technical Reports Server (NTRS)

    Gladden, Roy E.; Khanampompan, Teerapat; Edmonds, Karina

    2008-01-01

    A computer program called dsn config converter automates what had been a manual process for updating the multimission adaptation file (multi.aaf) used by a multiple-mission-command-sequence-generating process comprised of a combination of the AUTOGEN and APGEN programs mentioned in the immediately preceding article. The program converts the dsn_config.cvf file that provides DSN (Deep Space Network) antenna configuration code mappings from a context variable file (CVF) format used in another part of the command generation process to an APGEN activity file (AAF) format used by AUTOGEN and APGEN. Whereas previously, the information in the dsn_config.cvf file was manually encoded into the multi.aaf file, now the program automatically generates a dsn_config.aaf file from the dsn_config.cvf file. As part of this development effort the multi.aaf file was adapted to use the new dsn_config.aaf representations. Through this automation a tedious error-prone step has now been replaced by a quick and robust step.

  4. 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...

  5. 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...

  6. Extreme makeover: converting one cell into another.

    PubMed

    Zhou, Qiao; Melton, Douglas A

    2008-10-01

    Cells of adult mammals can be converted (reprogrammed) to new cells. In one approach, adult cells are converted to pluripotent stem cells, followed by differentiation to regenerate new cell types. Alternatively, adult cells may be directly converted into other mature cells or progenitors. We discuss and compare these two approaches with particular emphasis on the latter and its relevance for regenerative medicine. PMID:18940730

  7. [Measuring converter for elastometric medical instruments].

    PubMed

    Shifrin, L I; Belov, V V; Cherny?, V M; Orlov, Iu M

    1980-01-01

    According to thorough consideration of converting characteristics of elastometric instruments, the measurement error can be diminished by introducing in the measuring converter some regulation means for the angle of the moment of counteracting springs and an assembly to limit the radial shift of the converter moving part. Such a modification provides high operational and metrologic characteristics for elastometric medical instruments. PMID:6446637

  8. 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

  9. 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.

  10. A zero power harmonic transponder sensor for ubiquitous wireless ?L 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 ?L-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

  11. Second harmonic generation study of local polar inhomogeneities in Pb3(MgNb2)O9

    NASA Astrophysics Data System (ADS)

    Pugachev, A. M.; Kovalevskii, V. I.; Malinovskii, V. K.; Malitskaya, M. A.; Raevskaya, S. I.; Raevskii, I. P.; Surovtsev, N. V.

    2015-03-01

    The temperature dependence of the second harmonic generation in the lead magnesium niobate (Pb3(MgNb2)O9) crystal has been studied. It has been shown that the second harmonic generation in the crystal occurs in local non-centrosymmetric regions in the sample bulk, whereas a similar response from a fine powder is caused by effects associated with decreasing grain sizes. Maximum changes in polarization in local regions occur near the Vogel-Fulcher temperature in the range of 200-270 K. In the same temperature range, according to the published data, gradual freezing of polar regions and the formation of an infinite cluster is assumed.

  12. Highly efficient second-harmonic generation of intense femtosecond pulses with a significant effect of cubic nonlinearity

    SciTech Connect

    Mironov, S Yu; Ginzburg, V N; Lozhkarev, V V; Luchinin, G A; Kirsanov, Aleksei V; Yakovlev, I V; Khazanov, Efim A; Shaykin, A A

    2011-11-30

    A highly efficient (73%) second-harmonic generation of femtosecond pulses in a 1-mm-thick KDP crystal at a fundamentalharmonic peak intensity of 2 TW cm{sup -2} has been demonstrated experimentally. In a 0.5-mm-thick KDP crystal, a 50% efficiency has been reached at a peak intensity of 3.5 TW cm{sup -2}. We examine the key factors that limit the conversion efficiency and present numerical simulation results on further temporal compression of second-harmonic pulses.

  13. 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.

  14. Crystal growth and characterization of semiorganic single crystals of L-histidine family for NLO applications

    NASA Astrophysics Data System (ADS)

    Anandan, Pandurangan; Jayavel, Ramasamy

    2011-05-01

    Single crystals of L-histidine hydrochloride monohydrate and tartaric acid mixed L-histidine hydrochloride monohydrate have been grown by slow evaporation solution growth technique from appropriate mixtures of respective chemicals. Single crystal and powder X-ray diffraction analyses, Fourier transform infrared, nuclear magnetic resonance spectral analysis, thermo-gravimetric (TG), differential thermal analysis (DTA) have been employed to characterize the as-grown crystals. It is observed to be a wide transparency window for both the crystals from 300 to 1000 nm, which is suitable for second harmonic generation of laser in the blue region. Nonlinear optical characteristics have been studied using Q switched Nd: YAG laser ( ?=1064 nm). The second harmonic generation conversion efficiency of the grown crystal shows the suitability for frequency conversion applications.

  15. Frequency-doubling broadband light in multiple crystals

    SciTech Connect

    Alford, William J.; Smith, Arlee V.

    2001-04-01

    We 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, we 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 a broad bandwidth.

  16. Low work function silicon collector for thermionic converters

    NASA Technical Reports Server (NTRS)

    Chang, K. H.; Shimada, K.

    1976-01-01

    To improve the efficiency of present thermionic converters, single crystal silicon was investigated as a low work function collector material. The experiments were conducted in a test vehicle which resembled an actual thermionic converter. Work function as low as 1.0eV was obtained with an n-type silicon. The stabilities of the activated surfaces at elevated temperatures were tested by raising the collector temperature up to 829 K. By increasing the Cs arrival rate, it was possible to restore the originally activated low work function of the surface at elevated surface temperatures. These results, plotted in the form of Rasor-Warner curve, show a behavior similar to that of metal electrode except that the minimum work function was much lower with silicon than with metals.

  17. Potentials of LiGa(S 1-xSe x) 2 mixed crystals for optical frequency conversion

    NASA Astrophysics Data System (ADS)

    Huang, J.-J.; Atuchin, V. V.; Andreev, Yu. M.; Lanskii, G. V.; Pervukhina, N. V.

    2006-07-01

    Phase-matching conditions are considered for second harmonic generation (SHG) and optical parametric generation in LiGa(S 1-xSe x) 2 mixed crystals as a function of chemical composition under the supposition of linear dependence of refractive indices on x. It has been shown that by tuning x over the range 0-1 the SHG can be realized in XY plane for ?=2.1-7.8 ?m pumping at ?=43-90, in YZ plane for ?=2.1-2.2 and 4.8-7.8 ?m pumping at ?=0-90, and in XZ plane for ?=1.6-11.7 ?m pumping at ?=0-57. The LiGa(S 1-xSe x) 2 solid solutions are also attractive for design of tunable femtosecond pulse frequency converters with saving of pump pulse duration.

  18. A Carrier-Phase Control Suitable for Conducted EMI Noise Reduction in a Multiple-Converter System

    NASA Astrophysics Data System (ADS)

    Tamate, Michio; Toba, Akio; Matsumoto, Yasushi; Wada, Keiji; Shimizu, Toshihisa

    Conducted EMI noise flowing from the power converters to AC utility line is regulated by international commissions such as International Electrotechnical Commission (IEC). For adherence to the IEC regulations, EMI filters should be used in power electronics equipment. This paper proposes a method for analyzing the conducted EMI noise in multiple power converters connected to the same power line. In this method, the phase difference between sub-harmonic modulated carrier signals at each power converter is taken into account. The phase difference among the power converters determines the EMI noise level in a multiple-converter system, as is evident from the analysis of the waveform of the common-mode current. In addition, EMI noise suppression using a carrier-phase control is a proposed. In order to reduce volume of the EMI filter effectively, the phase difference θ should be set to 360/nN° here, n is a high-order harmonic component at around 150kHz, and N is the number of power converters. Therefore, the conducted EMI noise can be reduced effectively with the help of the proposed phase control.

  19. High harmonic cusptron device with an inverted structure

    SciTech Connect

    Kim, J.; Faith, J.; Kuo, S.P.

    1994-12-31

    An e-beam driven coherent radiation source operating at high cyclotron harmonic is designed. This device, called inverted cusptron, has a coaxial line configuration structured with both slotted central line and outer conductor. It used a cusp-magnetic field to convert a hollow e-beam produced from an annular thermionic cathode into an e-layer as the radiation source. The advantageous feature of the tube is that the central cylindrical tube of the structure can be used as input-output ports for an amplifier setup. A particle simulation code is developed to study the interaction between the electrons in the e-layer and the mode fields of the tube. The optimum design parameters such as the dimensions of the tube, electron beam energy, and magnetic field in order to obtain the maximum efficiency of the device for the TE{sub 02} 2{pi} mode are determined by the results of simulations. Five harmonics (N = 6, 8, 10, 12, 16) are considered, and the corresponding tube parameters are tabulated. It is found that the efficiency of the tube is insensitive to the relative position between the inner and outer slots. On the other hand, it is strongly dependent on the configuration of the cathode ring. Considering an electron beam produced by a 1/4 ring cathode (i.e. a 90{degree} arc length), the optimum conversion efficiencies of the five tubes are calculated to be 25%, 23%, 16%, 11%, and 9% respectively at an output frequency around 20GHz. The experiment to test the sixteenth harmonic tube has been set up. The preliminary experimental results will also be reported.

  20. 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.

  1. Harmonic considerations for electrical distribution feeders

    NASA Astrophysics Data System (ADS)

    1988-03-01

    Harmonics on the electric power distribution system can cause motor overheating, capacitor failures,watt-hour meter error, and relay malfunctions. The degree of problems caused by harmonics is greatly dependent on the characteristics of the distribution feeder, which can absorb a considerable percentage of its capacity in harmonic currents without ill effects. However, power factor correction capacitors can cause resonances near harmonic voltages that can result in intolerable distortion. Both motor loads and resistive loads can decrease the effect of resonance significantly. This report describes useful techniques to analyze, suppress, and measure harmonics on distribution feeders. Applicable areas for manual analysis and computer analysis are explained. The basic formulae are presented as well as sophisticated computer methods. Emphasis is placed on the fundamental principle. Models of harmonic-producing devices are presented and their limitations discussed. Most distribution feeder harmonics analyses can be performed using simple current source models. Filtering of specific loads and general, dispersed load is discussed. The fundamental principle in filtering distribution feeders is to shorten the harmonic current path. 3-dimensional plots enhance the understanding of the filtering action. Equipment and procedures for making measurements are described.

  2. 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.

  3. 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.

  4. 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.

  5. An extended stochastic harmonic analysis algorithm: Application for dissolved oxygen

    NASA Astrophysics Data System (ADS)

    Abdul-Aziz, Omar I.; Wilson, Bruce N.; Gulliver, John S.

    2007-08-01

    An extension of classical harmonic analysis is used to determine the Fourier coefficients with a constraint of forcing the function through a specified value for developing an extended stochastic harmonic analysis (ESHA). The methodology was applied to the diurnal variations of dissolved oxygen (DO) in streams within a semiempirical modeling scheme to demonstrate the formulation of an ESHA algorithm. Since DO values are often measured at different times during the day, the ESHA algorithm was used to convert data measured at any clock time to those at a standard or reference time. The model was evaluated for five different streams in Minnesota that capture the impact of different ecoregions and different sizes of watersheds. Data were normalized to increase the general applicability of the fitted parameters. The ESHA was successful in representing observed diurnal variations in DO. The root-mean-square error (RMSE) for predicting hourly DO and standard DO ranged respectively from 0.43 to 0.77 mg/L and 0.37 to 0.90 mg/L among the five streams. Estimated model parameters were robust in terms of both spatial and temporal variations. Parameter uncertainties and associated model sensitivity were demonstrated analytically. The developed algorithm can be used for similar applications in numerous science and engineering disciplines. In particular, it is a potentially useful tool for total maximum daily load (TMDL) assessment of aquatic ecosystem health across a range of spatial and temporal scales.

  6. XUV frequency combs based on intracavity high harmonic generation

    NASA Astrophysics Data System (ADS)

    Jones, R. Jason

    2014-05-01

    Intracavity high harmonic generation utilizing femtosecond enhancement cavities (fsEC's) has been established as an efficient route for the generation of femtosecond frequency combs in the vacuum-ultraviolet (VUV) to the extreme-ultraviolet (XUV) spectral regions. Such VUV/XUV frequency combs enable precision spectroscopy of atomic and potentially molecular spectra in an otherwise difficult to access spectral region. An improved understanding of the intracavity ionization dynamics that currently limit pulse enhancement has enabled a new generation of XUV frequency comb sources with significantly higher powers, at the >10 microwatt level per harmonic order extending below 50nm. We have developed a novel time-resolved pump-probe measurement technique to monitor and characterize the intracavity ionization dynamics by utilizing the sensitive response of the fsEC resonance itself to plasma induced nonlinear phase shifts. In recent work, we have developed a high power dual-frequency comb system based on Yb-fiber laser technology. The two phase-coherent frequency combs can be up-converted to the VUV/XUV using the fsEC. Dual-comb spectroscopy has already been established as a powerful spectroscopic method in the infrared. It's extension to the VUV/XUV spectral region will enable robust and high precision direct frequency comb spectroscopy of complex atomic and molecular structure in this spectral region.

  7. 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.

  8. 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. PMID:22879345

  9. 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.

  10. 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.

  11. Lunar gravity - A harmonic analysis

    NASA Technical Reports Server (NTRS)

    Ferrari, A. J.

    1977-01-01

    A sixteenth-degree and sixteenth-order spherical harmonic lunar gravity field has been derived from the long-term Keplerian variations in the orbits of the Apollo subsatellites and Lunar Orbiter 5. This model resolves the major mascon gravity anomalies of the lunar near side and is in very good agreement with line-of-sight acceleration results. The far-side map shows the major ringed basins to be strong localized negative anomalies located in broad regions of positive gravity which correspond closely to the highlands. The rms pressure levels calculated from equivalent-surface height variations show that the moon and earth support nearly equal pressures, whereas Mars is appreciably stronger. The moon appears to support larger loads than earth owing to its weaker central gravity field and perhaps a colder upper lithosphere. Significant differences between the low-degree gravity and topography spectra indicate that the longer-wavelength topographic features are isostatically compensated.

  12. 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.

  13. The myosin converter domain modulates muscle performance.

    PubMed

    Swank, Douglas M; Knowles, Aileen F; Suggs, Jennifer A; Sarsoza, Floyd; Lee, Annie; Maughan, David W; Bernstein, Sanford I

    2002-04-01

    Myosin is the molecular motor that powers muscle contraction as a result of conformational changes during its mechanochemical cycle. We demonstrate that the converter, a compact structural domain that differs in sequence between Drosophila melanogaster myosin isoforms, dramatically influences the kinetic properties of myosin and muscle fibres. Transgenic replacement of the converter in the fast indirect flight muscle with the converter from an embryonic muscle slowed muscle kinetics, forcing a compensatory reduction in wing beat frequency to sustain flight. Conversely, replacing the embryonic converter with the flight muscle converter sped up muscle kinetics and increased maximum power twofold, compared to flight muscles expressing the embryonic myosin isoform. The substitutions also dramatically influenced in vitro actin sliding velocity, suggesting that the converter modulates a rate-limiting step preceding cross-bridge detachment. Our integrative analysis demonstrates that isoform-specific differences in the myosin converter allow different muscle types to meet their specific locomotion demands. PMID:11901423

  14. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    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.

  15. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    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.

  16. Cryogenic Power Converter Module Performance

    NASA Astrophysics Data System (ADS)

    Hennessy, M. J.; Mueller, E. K.; Mueller, O.; Park, J. N.; Neal, R. R.

    2006-03-01

    Several cryogenic power converter modules were built and tested, including a low-voltage, high-power series based on Cryo-MOSFETs and a high-voltage, high-power series based on Cryo-IGBTs. Half-bridge modules were manufactured and demonstrated in liquid nitrogen. The hardware is such that several half-bridge modules can be interconnected to form a multiphase full bridge. Conduction losses in the MOSFET modules were reduced by more than an order of magnitude. Switching powers up to 340 kW were achieved in the MOSFET modules, and 720 kW was demonstrated in the IGBT series. These modules can be utilized in fully integrated, megawatt-level cryogenic power systems.

  17. Enhancing harmonic generation using nonlinear Metamaterials

    NASA Astrophysics Data System (ADS)

    Silva, Sinhara; Sonju, Kim; Zhou, Jiangfeng

    2015-03-01

    In this work, we demonstrate the double-resonator meta-atom design in a nonlinear metamaterial can significantly enhance harmonics in microwave frequency regime. Nonlinearity in the structure is introduced by adding a varactor diode in the common slit of the double split ring resonator (DSRR) design. By engineering the structure such that inner ring resonance frequency of the DSRR is twice as the outer ring resonance frequency, we have demonstrated that the second harmonic of the outer ring can be enhanced by factor of 70 compared to a conventional SRR structure. Furthermore, the second harmonic of the periodic arrays can be further improved by carefully positioning the unit cells. In addition, with the enhancement of the second harmonic, other higher order harmonics can be enhanced.

  18. Harmonizing national with international standards in Japan

    SciTech Connect

    Hohki, Keiichi; Hammons, T.J.

    1996-05-01

    This paper presents a Japanese engineer`s view on harmonization of global standards as the key factor in maintaining and promoting free trade. Japan is endowed with almost no natural resources, and, for this reason, Japan must rely on international trade to sustain its standard of living. Japan fully recognizes that the maintenance and promotion of mutually beneficial free trade is indispensable for cooperation in an international society, and is essential for Japan`s survival. It is very clear that the promotion of the international harmonization of standards is the key factor in the maintenance and promotion of free trade. And Japan is one of the countries most eagerly hoping for its realization. The authors focus on three issues concerning the international harmonization of Japanese standards: (1) Efforts Japan has made for the harmonization of Japanese standards with international ones; (2) natural or tectonic circumstances unique to Japanese standards; and (3) relationship between standard harmonization and international trade.

  19. Power Factor Correction to Mitigate Harmonic Distortion

    NASA Astrophysics Data System (ADS)

    Kochetkov, Gary

    Many direct current (DC) devices must receive their power from the alternating current (AC) grid. Rectifiers use diodes to create DC for these devices. Due to diodes' non-linear nature however, harmonics are created and these travel back into the grid. A significant presence of harmonics causes component heating and possible malfunction. A harmonic mitigation procedure is needed. With the correct usage of transistors, the current drawn by a rectifier can be manipulated to remove almost all harmonics. This process is called power factor correction (PFC), and formally acts to reduce the total harmonic distortion (THD) of the current. To investigate this, a three phase active rectifier was computer simulated and a controller was designed to provide switching signals for the transistors. Finally, the device was constructed in the laboratory to drive a DC motor, verifying its operating principle outside of the idealities of simulation.

  20. Crystal growth and optical properties of 4-aminobenzophenone (ABP)

    NASA Astrophysics Data System (ADS)

    Li, Zhengdong; Wu, Baichang; Su, Genbo; Huang, Gongfan

    1997-02-01

    Bulk crystals of 4-aminobenzophenone (ABP) were grown from organic solution. The crystal structure was determined by X-ray analysis. The refractive indices were determined by the method of prism minimum deviation. Some effective nonlinear-optical coefficients deff were measured. A blue second-harmonic emission with wavelengths of 433 and 460 nm were observed during laser diode pumping.

  1. 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.

  2. Efficient second harmonic conversion efficiency through one-dimensional coupled resonator poled nonlinear optical waveguide

    NASA Astrophysics Data System (ADS)

    Hamidi, S. M.; Parvini, T.; Tehranchi, M. M.

    2013-05-01

    In this paper, the second harmonic generation in finite size one-dimensional coupled resonator poled nonlinear optical waveguide has been investigated. To calculate the conversion efficiency, fundamental and second harmonic wave propagation among two proposed structures, we use the transfer matrix method. In the designed nonlinear photonic crystal structure, the linear and nonlinear optical parameters are both periodically modulated, and thus the second harmonic generation efficiency can be several orders of magnitude larger than in a conventional quasi-phase-matched nonlinear structure with the same sample length. In fact, due to the presence of a photonic band gap in a slow wave system, the density of states of the electromagnetic fields is large at the photonic band edge and photonic defect modes, and thus the group velocity is small, and the local field is enhanced. All these factors contribute to significant enhancement of the nonlinear optical interactions.

  3. 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)

  4. 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

  5. Near BPS skyrmions and restricted harmonic maps

    NASA Astrophysics Data System (ADS)

    Speight, J. M.

    2015-06-01

    Motivated by a class of near BPS Skyrme models introduced by Adam, Snchez-Guilln and Wereszczy?ski, the following variant of the harmonic map problem is introduced: a map ? :(M, g) ?(N, h) between Riemannian manifolds is restricted harmonic if it locally extremizes E2 on its SDiff(M) orbit, where SDiff(M) denotes the group of volume preserving diffeomorphisms of (M, g), and E2 denotes the Dirichlet energy. It is conjectured that near BPS skyrmions tend to restricted harmonic maps in the BPS limit. It is shown that ? is restricted harmonic if and only if ?? h has exact divergence, and a linear stability theory of restricted harmonic maps is developed, from which it follows that all weakly conformal maps are stable restricted harmonic. Examples of restricted harmonic maps in every degree class R3 ? SU(2) and R2 ?S2 are constructed. It is shown that the axially symmetric BPS skyrmions on which all previous analytic studies of near BPS Skyrme models have been based, are not restricted harmonic, casting doubt on the phenomenological predictions of such studies. The problem of minimizing E2 for ? :Rk ? N over all linear volume preserving diffeomorphisms is solved explicitly, and a deformed axially symmetric family of Skyrme fields constructed which are candidates for approximate near BPS skyrmions at low baryon number. The notion of restricted harmonicity is generalized to restricted F-criticality where F is any functional on maps (M, g) ?(N, h) which is, in a precise sense, geometrically natural. The case where F is a linear combination of E2 and E4, the usual Skyrme term, is studied in detail, and it is shown that inverse stereographic projection R3 ?S3 ? SU(2) is stable restricted F-critical for every such F.

  6. 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.

  7. 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).

  8. Incident IR Bandwidth Effects on Efficiency and Shaping for Third Harmonic Generation of Quasi-Rectangular UV Longitudinal Profiles

    SciTech Connect

    Not Available

    2010-12-07

    The photocathode of the proposed LCLS RF Photoinjector will be irradiated by uv laser light which is generated as the third harmonic of incident fundamental ir laser light. We have investigated quantitatively the effect of input ir spectral bandwidth on the exiting longitudinal intensity profiles, energy conversion efficiencies and spectral bandwidths that characterize the third harmonic generation (THG) process with a pair of crystals. These profiles, efficiencies and bandwidths include the residual fundamental and residual second harmonic light exiting the second crystal. The intrinsic acceptance bandwidth for THG is determined by crystal material and thickness as well as the type of phase matching that is used. For our case of BBO material with type I phase matching these bandwidths are approximately 0.9 nm*cm and 0.1 nm*cm for second and third harmonic generation respectively. Consequently for fixed crystal thicknesses and a fixed input ir longitudinal profile, the specified input ir bandwidth will determine the profiles, efficiencies and bandwidths exiting the second crystal. The results reported here are predictions of the SNLO code that is available as 'freeware' from the Sandia National Laboratories. It has been modified for this work. It is critical to note that this modification has enabled us to generate SNLO predictions of the 'coupled' case in which the output of the first crystal is used as input to the second crystal. Our focus is the dependence of uv longitudinal intensity profile and THG efficiency on the input ir bandwidth and crystal thicknesses. We include here cases that best illustrate input bandwidth effects. The criteria for selection of reported cases are highest efficiency generation of quasi-rectangular uv profiles with proportional intensity ripple less than 5% rms on the plateau of the pulse. Maximizing THG efficiency typically amounts to maximizing the crystal thicknesses with the longitudinal profile constraint. The specified incident ir longitudinal profile is quasi-rectangular (i.e. nonzero risetime and falltime with small intensity variation on the plateau) with a 10 psec pulse duration (FWHM). By assumption, this profile has been established upstream of the crystals at the fundamental ir wavelength. The simplest possible optical configuration is used in this work as shown in figure 1. The first crystal is the site of second harmonic generation (SHG) driven by the incident ir irradiation of central wavelength, 800nm. Downstream of the first crystal, the second crystal is the site of third harmonic generation (THG) which occurs by sum frequency mixing. Inter-crystal optics (such as a half waveplate) are assumed to be lossless at the fundamental and second harmonic wavelengths. As shown in figure 1, a portion of the incident ir irradiation is not sequestered from the first crystal for subsequent THG in the second crystal. Also, quasi-phase matching configurations and other complex compensation schemes have not been investigated at this point. The simplistic geometry better elucidates the intrinsic acceptance bandwidth limitations imposed by the crystals. Our goal in this endeavor has been to conduct a quantitative assessment of incident ir bandwidth effects on the THG process for BBO material of varied thicknesses and not, at this stage, to comply with all uv pulse specifications for the LCLS RF Photoinjector. Nonetheless, our results can be compared with LCLS photoinjector uv pulse requirements which call for a nominal 10 psec FWHM with 1 psec risetime and falltime and a nominally flat plateau (allowing for slope adjustments) with no more than a 5% rms proportional intensity variation. Furthermore, the results of this work can be used to suggest crystal thicknesses that would likely comply with all uv pulse requirements given the appropriate longitudinal profile and bandwidth for an input ir pulse.

  9. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K. (Golden, CO)

    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. Generalized harmonic Wang-Ball surface

    NASA Astrophysics Data System (ADS)

    Kherd, Ahmed; Saaban, Azizan

    2015-12-01

    In this paper, we present a method to generate Wang-Ball surface from two opposite prescribed boundaries based on the elliptic partial differential operators. In particular, we focus on the study of the harmonic Wang-Ball surfaces. The main result we report here is that any harmonic Wang-Ball surface would enable the overall surface to be generated and controlled based on the boundary curves rather than a set of control points. To visualize our proposed method we have chosen Harmonic Wang-Ball patches of degree 2 and degree 3.

  11. Contribution of zonal harmonics to gravitational moment

    NASA Technical Reports Server (NTRS)

    Roithmayr, Carlos M.

    1990-01-01

    A celestial body produces a gravitational moment about the mass center of a small orbiting body, which affects the orientation of the smaller body. Each zonal harmonic in the gravitational potential of a celestial body is shown to make a contribution to the gravitational moment which can be expressed in a recursive vector-dyadic form. A formal derivation is presented, followed by an example in which the result is employed in obtaining the contribution of the zonal harmonic of 2nd degree. The contribution of the zonal harmonic of 3rd degree is also reported.

  12. Conical harmonic generation in isotropic materials.

    PubMed

    Moll, K D; Homoelle, D; Gaeta, Alexander L; Boyd, Robert W

    2002-04-15

    A novel class of nonlinear optical processes is described in which radiation at the nth harmonic is generated through the use of a (2n+1)-order nonlinearity. Utilizing an odd-order nonlinearity, this process allows for the generation and amplification of both odd- and even-order harmonics in isotropic materials. Additionally, this process can always be phase matched in normal-dispersion materials without the use of birefringence. Experimental results are presented in which conical third-harmonic emission is generated from a sapphire sample. PMID:11955196

  13. 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.

  14. On Harmonic Measure of Critical Curves

    NASA Astrophysics Data System (ADS)

    Rushkin, Ilia; Bettelheim, Eldad; Gruzberg, Ilya; Wiegmann, Paul

    2006-03-01

    Fractal geometry of critical curves appearing in 2D critical systems is characterized by their harmonic measure. For systems described by conformal field theories with central charge c<=1 the scaling exponents of the harmonic measure have been computed by B. Duplantier [Phys. Rev. Lett. 84, 1363 (2000)] by relating the problem to boundary two-dimensional gravity. We present a simple argument connecting the harmonic measure of critical curves to operators obtained by fusion of primary fields, and compute characteristics of the fractal geometry by means of regular methods of conformal field theory. The method is not limited to theories with c<=1.

  15. Enhanced harmonic generation and carrier-envelope phase-dependent effects in cavity quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Li, Jiahua; Yu, Rong; Ding, Chunling; Zhang, Duo; Wu, Ying

    2015-07-01

    A lot of experimental and theoretical studies of a system in cavity quantum electrodynamics (cavity QED), which consists of two spatially separated quantum emitters strongly coupled to a single optical cavity mode, have recently attracted much interest in the quantum optics community for various quantum information applications. Here, we propose a method for high-order harmonic generation in a photonic crystal microcavity coupled to single semiconductor quantum dots (QDs). The system is coherently driven by a bichromatic laser consisting of the control and signal fields at low input power (a few nanowatts) and the cavity output power via the cavity loss channel is monitored. Via numerical simulations, we thoroughly explore the difference of the generated high-order harmonic spectra between two QDs, one QD, and zero QDs in microcavity. The results clearly indicate that harmonic generation can be significantly enhanced via collective coherent coupling in the case of two spatially separated QDs coupled to the same photonic crystal microcavity mode. In addition, we present a study of the carrier-envelope phase (CEP) effect on high-order harmonic spectra, which may provide the insight of CEP effect in a new regime. Beyond this, our obtained results also apply to other classes of single-mode cavity-QED setup incorporating two-level atoms or comparable solid-state emitters.

  16. Ocean floor mounting of wave energy converters

    SciTech Connect

    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.

  17. High voltage photovoltaic power converter

    DOEpatents

    Haigh, Ronald E. (Arvada, CO); Wojtczuk, Steve (Cambridge, MA); Jacobson, Gerard F. (Livermore, CA); Hagans, Karla G. (Livermore, CA)

    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.

  18. 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.

  19. 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 PaturleCoppens 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.

  20. 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.

  1. 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

  2. Harmonic Analysis on Quantum Tori

    NASA Astrophysics Data System (ADS)

    Chen, Zeqian; Xu, Quanhua; Yin, Zhi

    2013-09-01

    This paper is devoted to the study of harmonic analysis on quantum tori. We consider several summation methods on these tori, including the square Fejér means, square and circular Poisson means, and Bochner-Riesz means. We first establish the maximal inequalities for these means, then obtain the corresponding pointwise convergence theorems. In particular, we prove the noncommutative analogue of the classical Stein theorem on Bochner-Riesz means. The second part of the paper deals with Fourier multipliers on quantum tori. We prove that the completely bounded L p Fourier multipliers on a quantum torus are exactly those on the classical torus of the same dimension. Finally, we present the Littlewood-Paley theory associated with the circular Poisson semigroup on quantum tori. We show that the Hardy spaces in this setting possess the usual properties of Hardy spaces, as one can expect. These include the quantum torus analogue of Fefferman's H1-BMO duality theorem and interpolation theorems. Our analysis is based on the recent developments of noncommutative martingale/ergodic inequalities and Littlewood-Paley-Stein theory.

  3. Transparent ferroelectric glass-ceramics for second harmonic generation and electro-optic device applications

    NASA Astrophysics Data System (ADS)

    Nukavarapu, Syam Prasad; Jain, Himanshu; Toulouse, Jean; Esembeson, B.; Biaggio, Ivan; Wang, Jausheng

    2004-10-01

    There is strong need for low cost, optically active materials whose high electro-optic (EO) and second harmonic generation (SHG) properties can be engineered flexibly, in bulk and fiber forms. Therefore, we have fabricated transparent ferroelectric composites consisting of strontium barium niobate crystallites in a refractive index compatible tellurium oxide (TeO2) glass matrix. Several glass compositions, in the series x SrO-(10-x) BaO-y (Nb2O5)-(90-y) TeO2 (where x=2.5, 5 and 7.5 and y = 10, 15, 20 and 25), have been prepared by a conventional melt quenching technique. The compositions have been selected on the basis of thermal stability data obtained from differential thermal analysis (DTA). X-ray diffraction studies indicate ferroelectric phase formation in the controlled crystallized glasses. The non-centrosymmetric nature of the crystallized regions has been monitored via observing the second harmonic signal.

  4. 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)

  5. 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

  6. 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.

  7. Simultaneous type I and type II ?erenkov-phase matched second-harmonic generation in disordered nonlinear photonic structures.

    PubMed

    Ayoub, Mousa; Palick, Markus; Imbrock, Jrg; Denz, Cornelia

    2015-11-01

    We observe simultaneous type I and II ?erenkov-phase matched second-harmonic generation in a disordered nonlinear photonic crystal. The mean width of the disordered ferroelectric domains and the laser beam width are adjusted to be on the same length scale. We analyze the polarization properties, emission angles and intensities of each process. PMID:26561107

  8. Harmonic Control Based on Fuzzy Logic

    NASA Astrophysics Data System (ADS)

    Wu, Shihong; Dang, Gang; Wang, Jun; Li, Xiaohui; Zhang, Zhixia; Jiang, Fengli

    Proliferation of nonlinear loads in power systems has increased harmonic pollution and deteriorated power quality. Passive filtering has typically been the standard technology for harmonic and reactive power compensation .With the advancements in power electronics, active filtering is being more widely considered given its flexibility and precise control. However, cost, complexity, and reliability are considered the major drawbacks of active filters. In this paper a new fuzzy logic is introduced to control the harmonic in the power system, which has more advantages such as simplicity, ease of application, flexibility, speed and ability to deal with imprecision and uncertainties .The introduction of fuzzy logic can not only reduce harmonic,but also correct the power factor.

  9. Second Harmonic Detection Generated from Fastened Bolt

    NASA Astrophysics Data System (ADS)

    Fukuda, M.; Imano, K.

    The second harmonic components before/after the bolt was fastened were detected by using double-layered piezoelectric transducer (DLPT). The resonance frequency of DLPT changes to 1 MHz (f 0/2) when connected in parallel, but remains at 2 MHz (f 0) when connected in series. An effective fundamental transmission (1 MHz) is obtained when the DLPT is electrically connected in parallel while efficient second harmonic reception (2 MHz) is obtained when the DLPT is connected in series. In our system, the pulse inversion averaging (PIA) method was applied to enhance the second harmonic component. A hexagon head bolt (the diameter of a screw: 12 mm, the length: 100 mm) was used in experimental. The bolt was fastened by 40 N-m. The detected second harmonic component after the bolt was fastened was increased by approximately 10 dB compared with before the bolt was fastened.

  10. 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.

  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. Multisite EPR oximetry from multiple quadrature harmonics

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    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.

  13. CW, single-frequency 229nm laser source for Cd-cooling by harmonic conversion

    NASA Astrophysics Data System (ADS)

    Kaneda, Yushi; Yarborough, J. M.; Merzlyak, Yevgeny

    2015-02-01

    More than 200mW of CW 229nm for Cd atom cooling application was generated by the 4th harmonic of a single frequency optically pumped semiconductor laser using a 10-mm long, Brewster-cut BBO crystal in an external cavity. With 650mW of 458nm input, 216mW of 229nm power was observed. Conversion efficiency from 458nm to 229nm was more than 33%.

  14. 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.

  15. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L. Jeffrey (Pleasanton, CA); DeYoreo, James J. (Livermore, CA); Roberts, David H. (Pleasanton, CA)

    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.

  16. 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 Vickers microhardness, laser damage threshold (LDT) values and second harmonic generation (SHG) efficiencies are reported. Thermal and dielectric studies were also carried out.

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

    PubMed

    Moovendaran, K; Natarajan, S

    2014-08-14

    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. PMID:24747852

  18. 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.

  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. 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.

  1. Surface plasmon-enhanced transverse magnetic second-harmonic generation.

    PubMed

    Zheng, Wei; Hanbicki, Aubrey T; Jonker, Berry T; Lpke, Gunter

    2013-11-18

    We present experimental studies on surface plasmon (SP) enhanced transverse magnetic second-harmonic generation (T-MSHG) in single-crystal iron films grown by molecular beam epitaxy at room temperature on MgO (001) substrates. We show that it is possible to achieve both strongly enhanced T-MSHG intensity and high magnetic contrast ratio under attenuated total reflection configuration without using complex heterostructures because MSHG is generated directly at the iron surface where SPs are present. The T-MSHG has a much larger contrast ratio than transverse magneto-optical Kerr effect (T-MOKE) and shows great potential for a new generation of bio-chemical sensors due to its very high surface sensitivity. In addition, by analyzing the experimental results and the simulations based on SP field-enhancement theory, we demonstrate that the second-order susceptibility of MSHG shows great anisotropy and the tensor ?(xzz)(odd) is dominant in our sample. PMID:24514397

  2. 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.

  3. Spherical Harmonic Analysis via Bayesian Inference

    NASA Astrophysics Data System (ADS)

    Muir, J. B.; Tkalcic, H.

    2014-12-01

    The real spherical harmonics form a compact, simple and commonly used set of basis functions for describing fields in tomographic inverse problems. It is therefore often useful to perform spherical harmonic analysis on data to represent it in the spherical harmonic parametrisation. Most existing algorithms, based on Fourier transforms, require that data be interpolated to a regular grid; this is not appropriate for the sparse, irregularly distributed data found in many geophysical applications. Instead, this work casts the problem of spherical harmonic analysis as an inverse problem, and applies the methods of Bayesian inference to overcome regularization problems in the inversion. This allows irregular data to be easily handled, and directly provides error estimates for the inverted spherical harmonic parameters. Synthetic tests have shown that this method easily handles relatively large amounts of added Gaussian noise. So far, this method has been applied to estimate the power in each harmonic degree for tomographic maps of the deep mantle based on PKP-PKIKP and PcP-P differential travel times, showing that they agree at global length scales despite local heterogeneity results being heavily influenced by data coverage. This potentially allows for simple heuristic arguments to constrain the global variation in core-mantle boundary topography based on the similarity between PKP and PcP derived tomographic maps.

  4. 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.

  5. Harmonic Oscillators as Bridges between Theories

    NASA Astrophysics Data System (ADS)

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

    2005-03-01

    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.

  6. 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.

  7. Dual aperture dipole magnet with second harmonic component

    DOEpatents

    Praeg, Walter F. (Palos Park, IL)

    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.

  8. 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.

  9. CMB map derived from the WMAP data through harmonic internal linear combination

    SciTech Connect

    Kim, Jaiseung; Naselsky, Pavel; Christensen, Per Rex

    2008-05-15

    We are presenting an internal linear combination CMB map, in which the foreground is reduced through harmonic variance minimization. We have derived our method by converting a general form of pixel-space approach into spherical harmonic space, maintaining full correspondence. By working in spherical harmonic space, spatial variability of linear weights is incorporated in a self-contained manner and our linear weights are continuous functions of position over the entire sky. The full correspondence to pixel-space approach enables straightforward physical interpretation on our approach. In variance minimization of a linear combination map, the existence of a cross term between residual foregrounds and CMB makes the linear combination of minimum variance differ from that of minimum foreground. We have developed an iterative foreground reduction method, where perturbative correction is made for the cross term. Our CMB map derived from the WMAP data is in better agreement with the WMAP best-fit {lambda}CDM model than the WMAP team's internal linear combination map. We find that our method's capacity to clean foreground is limited by the availability of enough spherical harmonic coefficients of good signal-to-noise ratio.

  10. RF digital-to-analog converter

    DOEpatents

    Conway, P.H.; Yu, D.U.L.

    1995-02-28

    A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

  11. RF digital-to-analog converter

    DOEpatents

    Conway, Patrick H. (Rancho Palos Verdes, CA); Yu, David U. L. (Rancho Palos Verdes, CA)

    1995-01-01

    A digital-to analogue converter for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration.

  12. Pulse-Width-to-Analog-Voltage Converter

    NASA Technical Reports Server (NTRS)

    Sosack, G. S.; Simmons, N. E.

    1985-01-01

    Peak output voltage varies linearly with input-pulse duration. Circuit converts pulses of varying widths (as from sound-velocity instrumentation or tachometers) into analog voltages. Peak voltage increases in proportion to pulse width. Voltage used to drive an x-y plotter or storage oscilloscope. Pulse-width-to-voltage converter has peak output voltage that varies with duration of input pulses.

  13. Power Converters Secure Electronics in Harsh Environments

    NASA Technical Reports Server (NTRS)

    2013-01-01

    In order to harden power converters for the rigors of space, NASA awarded multiple SBIR contracts to Blacksburg, Virginia-based VPT Inc. The resulting hybrid DC-DC converters have proven valuable in aerospace applications, and as a result the company has generated millions in revenue from the product line and created four high-tech jobs to handle production.

  14. Controller for a wave energy converter

    SciTech Connect

    Wilson, David G.; Bull, Diana L.; Robinett, III, Rush D.

    2015-09-22

    A wave energy converter (WEC) is described, the WEC including a power take off (PTO) that converts relative motion of bodies of the WEC into electrical energy. A controller controls operation of the PTO, causing the PTO to act as a motor to widen a wave frequency spectrum that is usable to generate electrical energy.

  15. Passive Resonant Bidirectional Converter with Galvanic Barrier

    NASA Technical Reports Server (NTRS)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  16. Radiation Effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25.97 MeV-square cm/mg. This might be due to fact that the device is radiation hardened.

  17. Modelling, analyses and design of switching converters

    NASA Technical Reports Server (NTRS)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  18. 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.

  19. Second-harmonic generation of a continuous-wave diode-pumped Nd:YAG laser using an externally resonant cavity

    SciTech Connect

    Kozlovsky, W.J.; Nabors, C.D.; Byer, R.L.

    1987-12-01

    The authors report 13% second-harmonic conversion efficiency of a 15-mW, c-w, diode laser-pumped Nd: YAG oscillator. 2 mW of single-axial-mode 532-nm radiation was generated by externally resonant second-harmonic generation in a monolithic MgO-doped lithium niobate nonlinear crystal cavity. The measured finesse of 450 for the monolithic external cavity indicated that absorption and scatter losses in the doubler were less than 0.8%.

  20. Second-harmonic generation of a continuous-wave diode-pumped Nd:YAG laser using and externally resonant cavity

    SciTech Connect

    Kozlovsky, W.J.; Nabors, C.D.; Byer, R.L.

    1987-12-01

    We report 13% second-harmonic conversion efficiency of a 15-mW, cw, diode-laser-pumped Nd:YAG oscillator. 2 mW of single-axial-mode 532-mm radiation was generated by externally resonant second-harmonic generation in a monolithic MgO:LiNbO/sub 3/ nonlinear crystal cavity. The measured finesse of 450 for the monolithic external cavity indicated that absorption and scatter losses in the doubler were less than 0.8%.